US20050168320A1 - Electronic real estate lockbox system - Google Patents

Abstract

One or more lock or key units of a secure entry system is equipped with a radio receiver. The receiver permits a memory in the lock or key unit to be updated with new data that is modulated onto a radio frequency signal. By this technique, system-wide changes of programming data, such as changes of lockout lists and access codes, and changes targeted to specific units, such as disabling a particular key, can be implemented simply and quickly.

Description

RELATED APPLICATION DATA
• This application is a continuation in part of copending U.S. application Ser. No. 831,601, filed Feb. 21, 1986, which in turn is a continuation in part of copending application Ser. No. 814,364, filed Dec. 30, 1985, which in turn is a continuation in part of Ser. No. 788,072, filed Oct. 16, 1985, now abandoned. These applications are incorporated herein by reference.
BACKGROUND AND SUMMARY OF THE INVENTION
• The present invention relates to real estate lockboxes and other secure entry systems. Lockboxes are used in the real estate industry to contain the keys of houses listed for sale. Prior art lockboxes have primarily been mechanical devices which allow access to a secure compartment by use of a conventional key. Such lockboxes and keys, however, have had numerous disadvantages. These disadvantages have been overcome by the present invention and a great number of new features have been provided.
• One feature of the present invention is the provision of a code entry keypad on a lockbox key, rather than on the lockbox itself, thereby eliminating an opportunity for lockbox vandalism and preventing unauthorized passersby from communicating with the lockbox.
• Another feature of the invention is an arrangement whereby different keys can be programmed to become inoperative after different periods of time.
• Yet another feature of the invention is the ability of the lockbox to be reprogrammed in the field.
• Still another feature of the invention is the ability of the lockbox to be interrogated by a user to learn the number of times the lockbox has been accessed without returning the lockbox or an interrogating key to a central location.
• Yet another feature of the invention is an arrangement whereby a user can receive temporary authorization to access lockboxes owned by other real estate boards.
• Still another feature of the invention is an arrangement whereby lockbox battery power is conserved and solenoid work is reduced by delaying energization of unlocking solenoids until the lockbox is actually being opened.
• Yet another feature of the invention is the use of several independent lockbox battery monitoring criteria to avoid lockbox battery failure.
• Still another feature of the invention is the provision of two lockbox locking solenoids that are reciprocally mounted so that if one is jarred to an unlocked state, the other is jarred to maintain a locked state.
• Yet another feature of the invention is an arrangement whereby a manufacturer can provide a variety of different keys to its customers without tooling up several different manufacturing lines.
• Still another feature of the invention is an arrangement whereby real estate boards or agencies can limit the operations that individual keys can perform.
• Yet another feature of the invention is an arrangement whereby a user can log into a lockbox's access log without opening the lockbox.
• Still another feature of the invention is an arrangement whereby an agent who has listed a house can require visiting agents to enter an auxiliary access code before being allowed to open the lockbox.
• Yet another feature of the invention is the ability of the lockbox to render certain keys inoperative until they are reprogrammed.
• Still another feature of the invention is the recording of detailed diagnostic data about recent lockbox and key operations in order to facilitate resolution of anomalous lockbox and key behavior.
• Yet another feature of the invention is the ability of the lockbox to recognize the keys of preselected users and to prohibit them from opening the lockbox.
• Still another feature of the invention is the ability of the lockbox and key to cooperate so as to update a list of keys that are to be prevented from executing lockbox functions.
• Yet another feature of the invention is the use of a low power, yet long range electromagnetic communications technique for exchanging signals between lockbox, key and stand components.
• Still another feature of the invention is an arrangement whereby a user can enter the keystrokes needed to operate the lockbox into the key's keypad before the key is engaged with the lockbox, thereby facilitating operation of the lockbox in awkward or poorly lit locations.
• Yet another feature of the invention is an arrangement whereby the access log maintained in the lockbox can be marked so that less than the entire contents of the log can be supplied to a requesting user.
• The foregoing and additional features and advantages of the present invention will be more readily apparent from the following detailed description of a preferred embodiment thereof, which proceeds with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 shows a lockbox, a key, a stand and a computer used in a lockbox system according to the present invention.
• FIG. 2 is a rear view, partially in section, schematically illustrating portions of a lockbox according to the present invention.
• FIG. 3 is a sectional view taken along line3-3 ofFIG. 2, schematically illustrating some of the locking components in a lockbox according to the present invention.
• FIG. 4 is a top view of a shackle locking bar used in the lockbox ofFIGS. 2 and 3.
• FIG. 5 is a rear elevational view of the shackle locking bar ofFIG. 4.
• FIG. 6 is a right side view of a door stem used in the lockbox ofFIGS. 2 and 3.
• FIG. 7 is a front elevational view of a lockbox shackle used in the lockbox ofFIGS. 2 and 3.
• FIG. 8 is a sectional view of the case of the lockbox ofFIGS. 2 and 3 taken along line8-8 ofFIG. 2.
• FIG. 9 is a schematic block diagram of the electronic circuitry used in the lockbox ofFIGS. 2 and 3.
• FIG. 10 is a plan view of a key according to the present invention.
• FIG. 11 is a left side view of the key ofFIG. 10.
• FIG. 12 is a schematic block diagram of the electronic circuitry used in the key shown inFIGS. 10 and 11.
• FIG. 13 is a diagram illustrating portions of the electronic memories used by the lockbox and key of the present invention.
• FIG. 14 is a top plan view of a remote stand according to the present invention.
• FIG. 15 is a sectional view taken along lines15-15 ofFIG. 14 and showing the stand with two different sizes of keys.
• FIG. 16 is a sectional view taken along lines16-16 ofFIG. 14 and showing the stand coupled to a lockbox.
• FIG. 17 is a rear elevational view of the stand shown inFIG. 14.
• FIG. 18ais a schematic block diagram of the electronic circuitry used a local stand according to the present invention.
• FIG. 18bis a schematic block diagram of the electronic circuitry used in a remote stand according to the present invention.
• FIG. 19 is a schematic block diagram showing a digital reconstruction modulation system according to the present invention.
• FIG. 20 shows a radio system for updating lockboxes and keys according to the present invention.
• FIG. 21 shows a computer and trunk interface unit used in an enhanced version of the system ofFIG. 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENTGeneral Overview
• Abasic lockbox system10 according to the present invention, shown inFIG. 1, includes one or more lockboxes, or keysafes,12,electronic keys14, stands16 andcomputers18.Lockbox12 contains the door key to the listed dwelling and is mounted securely on or near the dwelling.Electronic key14 is used by real estate agents to open the lockbox and gain access to the dwelling key contained therein.Key14 can also be used to read access log data from the lockbox and to load programming instructions into it.Stand16 is used to interfacecomputer18 with the lockbox and key units.Computer18 is used to store instructions in and to collect data fromlockbox12 andkey14 so as to integrate management of a lockbox system.
Lockbox
• With reference toFIGS. 2-3,lockbox12 includes a secure enclosure, orhouse key compartment20 designed to contain house keys, business cards, written messages and the like.Lockbox12 is securely attached to the listed house or other fixed object by ashackle22 or by screws (not shown).Shackle22 in most instances attaches the lockbox to a doorknob, water spigot or porch guard rail. Upon a proper exchange of signals betweenlockbox12 and key14, adoor24 to the lockbox housekey compartment20 can be opened, thereby allowing access to the house key and to other materials stored inside.
• The circuitry oflockbox12 is shown in block diagram form inFIG. 9.Lockbox12 includes acommunications coil26, a microprocessor (CPU)28, a read/write (RAM)memory30, aprimary battery32, abackup battery34, a pair of keycompartment locking solenoids36, a pair ofshackle locking solenoids38, a key compartmentsolenoid drive circuit40, an associatedmicroswitch42 and a shacklesolenoid drive circuit43.
• Communications coil26 is used to electro-magnetically couple to corresponding coils inkey14 and stand16.Microprocessor28 controls operation oflockbox12 according to programming instructions (“lockbox control software”) permanently stored in an associated read only memory (ROM)44.RAM memory30 is used to store various elements and strings of operating data.Primary battery32 provides power to the lockbox circuitry.Backup battery34 is used when the primary battery becomes weak or is removed for replacement. Keycompartment locking solenoids36 releasably lock housekey compartment door24 under the control of doorsolenoid drive circuit40 andmicroswitch42.Shackle locking solenoids38releasably lock shackle22 under the control of shacklesolenoid drive circuit43.
• Although illustrated as a single component,lockbox CPU28 is in fact two discrete microprocessor circuits. The first, a National Semiconductor 820 Series Control Oriented Processor, is an eight bit processor that performs all control, communications and logic functions with the exception of timing and calendar-clock functions. These functions are performed by a National Semiconductor COP 498 processor which is mask programmed by the manufacturer to perform a variety of time keeping functions. Thelockbox RAM30 is comprised of a low power, low voltage Toshiba LC3517NC RAM circuit, which is organized as 2048 eight bit bytes.
• Lockbox CPU28 stores information on certain of the operations that are executed, or attempted to be executed, by a key or the lockbox in a portion ofRAM memory30 termed the “access log.” Each entry in the access log includes the identity of the key, the date and time of the operation (obtained from the calendar-clock portion of CPU28), the function attempted and, if the function was denied, the reason why. In the illustrated exemplary embodiment, the lockbox access log can store information on 100 lockbox operations. This log can later be retrieved, in whole or in part, by key14 or bystand16 for transfer tocomputer18 or for display on a CRT screen or printer.
• Management of the lockbox access log is performed bylockbox CPU28 in conjunction with a “roll flag” and a “pointer” stored inlockbox RAM30. The roll flag indicates whether all 100 entries in the access log have been filled and consequently whether the memory is recycling, overwriting old data. The pointer indicates the address of the memory location at which the next access log entry will be stored.
• When the lockbox is initialized (discussed below in the section entitled Initialization and Deactivation of Lockboxes and Keys by the Computer), the roll flag is set to “0” and the pointer is set to indicate the address of the first memory location in the access log. Thereafter, each entry in the log causes the pointer to increment to the address of the next memory location in the log.
• After 100 entries have been stored in the access log, the pointer recycles and indicates again the address of the first memory location in the access log. At this point, the rollover flag is set to “1,” indicating that the access log has become a circular data buffer and that each additional entry will overwrite an earlier entry.
Lockbox Characterization Instructions
• Lockbox12 is characterized by “lockbox characterization instructions” loaded intolockbox RAM memory30 by a computer through a stand. (Key14 can also be used to load a set of limited characterization instructions intolockbox RAM memory30, as discussed below in the section entitled Functions). The lockbox characterization instructions give the lockbox an identity, fix in it certain numerical values and enable it to perform certain functions.
• As shown in the illustrative lockbox memory map inFIG. 13, the identification information loaded with the characterization instructions identifies the listing, the listing agent, the responsible agency and the responsible board. The identification information further identifies the lockbox by a unique lockbox serial number.
• Some of the numerical values loaded into the lockbox include a “Shown By Arrangement” (SBA) number, a key lockout list and a collection of lockbox access codes.
• Functions enabled by function enable bits in the characterization instructions may include Lockbox Disable On Removal and Privacy Read (both discussed below in the section entitled Programmable Lockbox Options).
• After its initial characterization bystand16,lockbox12 will not require further maintenance or programming until the lockbox is moved to a new location.
• Mechanical details of thelockbox12 are discussed below in the section entitled Mechanical Construction of Lockbox.
Key
• With reference toFIGS. 10 and 11, key14 is constructed in atrim polycarbonate enclosure46 sized to fit conveniently in a user's purse or pocket. The key includes akeypad48 and anLCD display50.Keypad48 is used to enter commands into the key.LCD display50 is used to display instructions and information to the user.
• LCD display50 includes a central message portion in which messages from the system can be displayed to the user.Display50 also includes a lower portion comprising a “prompt” field and an upper portion comprising an “annunciator” field. The prompt field includes twelve potential prompts which represent twelve functions that a user can request the key to execute. They are OPEN, SHACKLE RELEASE, CHANGE PERSONAL CODE, CONTROLLER, READ FILE MARK, READ NN, READ, CLEAR MEMORY, SIGNATURE, SHOWN BY ARRANGEMENT, FILE MARK, and PROGRAM. These functions are discussed below in the section entitled Functions.
• The annunciator field includes five potential annunciators which indicate the status of various aspects of the key. The annunciators in the preferred embodiment are FUNCTION, READ, PROGRAM, KEYSAFE BATTERY and KEY BATTERY.
• The READ annunciator is made visible when the key contains lockbox access log data transferred from a lockbox during a READ operation. The PROGRAM annunciator is made visible when the key contains a set of limited characterization instructions that are to be loaded into a lockbox. The FUNCTION annunciator is made visible when the user is to select a function to be executed. The KEYSAFE BATTERY and the KEY BATTERY annunciators are made visible when the batteries for these respective units need attention.
• The circuitry ofkey14 is shown in block diagram form inFIG. 12.Key14 includes acommunications coil54, a key microprocessor (CPU)52, the keypad orother switch mechanism48, theLCD display50, a read/write memory (RAM)56, aprimary battery58, abackup battery60 and abeeper62.
• Communications coil54 is used to electromagnetically couple to the corresponding coils inlockbox12 and stand16.Microprocessor52 controls operation of key14 according to programming instructions (“key control software”) permanently stored in an associated read only memory (ROM)64.RAM memory56 again comprises a Toshiba LC3517NC RAM circuit and is used to store various elements and strings of operating data.Primary battery58 provides power to the key circuitry.Backup battery60 is used when the primary battery becomes weak or is removed for replacement.Beeper62 beeps to call the user's attention to the key in a variety of instances, such as when an error is committed or when the key and lockbox have successfully completed an operation.
• Although illustrated as a single component,key CPU52 also comprises two discrete microprocessor circuits. The first, a National Semiconductor 820 Series Control Oriented Processer, is an eight bit processor that performs all control, communications and logic functions except reading data fromkeypad48 and controlling operation ofLCD display50 andbeeper62. These functions are performed by a very low power NEC uPD7501 4 bit microcontroller with an on board LCD driver. The distribution of processing tasks between two processors in this manner reduces power consumption and increases operational efficiency by allocating the time consuming user interface chores to the very low power NEC processor, thereby allowing the logic functions to be more quickly performed using the higher power National processor.
Key Characterization Instructions
• Key14 is characterized by “key characterization instructions” loaded intokey RAM memory56 by a computer through a stand. These instructions give the key an identity, fix in it certain numerical values and enable it to perform certain functions.
• As shown in the illustrative key memory map inFIG. 13, the identification information loaded with the characterization instructions identifies the agent, the responsible agency and the responsible board. The identification information further identifies the key by a unique serial number.
• Some of the numerical values loaded with the key characterization instructions include a four digit personal code, permission codes for various of the functions and various key access codes with associated expiration dates.
• Functions enabled by function enable bits in the characterization instructions may include OPEN, READ and SHACKLE RELEASE.
• After its initial characterization bystand16, key14 will not require further programming until any time dependent functions which may have been enabled, such as key expiration date or expiring key access codes (discussed below) need updating.
Limited Function Keys
• This key described above can, if loaded with the proper characterization instructions, execute the entire complement of functions available on the system, here illustrated as twelve. In some applications, however, it is desirable to provide simpler keys which can effect only a limited range of functions. Thus, it may be desirable, for example, to provide keys that can perform just three functions: open a lockbox, drop a shackle and communicate with a computer. Such a simple key could be constructed without an LCD display.
• Limiting the functions that a key can perform can be effected by setting certain enable/disable bits inkey RAM memory56. In the preferred embodiment,key RAM memory56 has an enable/disable data bit corresponding to each of the twelve functions. If the enable/disable data bit corresponding to a function is set to a “1,” the function is enabled. If set to a “0,” the function is disabled.
• The enable/disable data inkey RAM memory56 is desirably set by the manufacturer so as to enable a particular set of functions. This arrangement permits the manufacturer to provide a variety of different keys to users having a variety of different requirements without the need to tool up a separate manufacturing line for each different key. If the manufacturer later wishes to change a key's enable/disable data, it can do so by reprogramming the this data itself or by providing software to the responsible real estate board that will enable the board computer to reprogram this data.
• In an alternative embodiment,key RAM memory56 can have two data bits corresponding to each of the twelve functions. One of these bits is set by the manufacturer to a “0” or a “1” and cannot be altered by the user. The other of these bits can be set to a “0” or a “1” by the authority that exercises supervisory control over the key, usually the local real estate board. In this alternative embodiment, the only functions that are enabled are those for which corresponding enable/disable data bits have both been set to a “1” by the appropriate authority. By this alternative system, the local real estate board is empowered to tailor the capabilities of its keys as it sees fit within the range of functions enabled by the manufacturer.
Programmable Time Constants
• In the preferred embodiment, all time constants in the both the lockbox and key are set by data bits stored in the respective unit' RAM memories (as illustrated by the lockbox and key memory maps ofFIG. 13). These time constants set, for example, the length of time each of the transient displays are maintained inLCD display50 and the length of time lockbox keycompartment unlocking solenoids36 are to be kept energized.
Stand
• Stand16 is used in the present invention to transfer information betweencomputer18 and the lockbox and key components of a lockbox system.
• With reference toFIGS. 14-17, stand16 can comprise anenclosure66 having aprotrusion68. Withinprotrusion68 is astand communications coil70. In use, a key or a lockbox is positioned onstand16 as shown inFIGS. 15 and 16, respectively. In these positions, the communications coil within the lockbox or key is positioned in proximity withstand communications coil70 inprotrusion68, thereby establishing electromagnetic coupling between such coils.
• In alternative embodiments,protrusion68 can be omitted. In such embodiments,communications coil70 can be disposed withinenclosure66 so that it is adjacent the coils in corresponding lockbox or key units when such units are placed on the stand.
• As illustrated inFIGS. 18aand.18b, stand16 is constructed in two forms. A first form of the stand, termed alocal stand16a, is designed to communicate with a computer at the same site. Local stands are thus intended for use at the board office, where they are tied directly to the board computer, or at agency offices, where they may be tied directly to a smaller computer.
• The second form of stand, termed aremote stand16b, is a portable unit designed to communicate with a remote computer over conventional telephone lines. Remote stands16bare thus typically used at agency offices that are not equipped with their own computers. Their portable nature, however, allows remote stands to be used wherever there is a phone line, such as at a property listed for sale, thereby enabling an agent to retrieve data from the board computer and provide a homeowner immediate information about listing activity.
• With reference toFIGS. 17, 18aand18b, both forms ofstand16 include a microprocessor (CPU)78, an associated read onlymemory80, a read/write memory (RAM)82 and aconnector83 for connection to a low voltage D.C. power supply.Local stand16afurther includes acable connector72 for connection to the local computer.Remote stand16bfurther includes amodem74 and two modular phone jacks76,77 for interfacing to a telephone line.First phone jack76 is used to connect to the outgoing phone line.Second phone jack77 is used to connect to a conventional telephone (not shown) which provides dialing signals on the outgoing phone line.Remote stand16balso includes aprinter output port79 for interfacing to a printer. This printer is driven by the remote computer through the stand and permits hard copy display of the data at the agency office or at the remote site at which the stand is used even though a computer is not locally available.
• Desirably,CPU78 comprises an Intel 8051 Series microprocessor andRAM82 comprises a NEC uPD4364 8192 by 8 bit static RAM.
• In order to ensure data security, stand16 desirably encrypts the lockbox and key data before it is sent to the computer. Conversely, stand16 decrypts the computer data before it is sent to the lockbox and key. This encryption/decryption is effected bymicroprocessor78 in conjunction with read onlymemory80 and read/write memory82.ROM memory80 contains the encryption and decryption algorithms used bystand16 in communicating withcomputer18.RAM memory82 is used for temporary storage of data used in this process.
• The encryption algorithms employed are such that if the same data is exchanged betweenstand16 andcomputer18 several times, the several transmissions will bear no resemblance to one another. Decryption by unauthorized eavesdroppers is thus deterred.
• In the preferred embodiment, the data exchanged betweenstand16 and the lockbox and key components is also similarly encrypted.
Stand Functions
• Stand16 can perform a variety of functions in the present invention. First, stand16 can provide a complete set of new characterization instructions forlockbox12 or key14, or can simply modify an existing set of instructions. This is done by placing the key or lockbox onstand16, as illustrated inFIGS. 15 and 16, and executing a recharacterization program oncomputer18. The recharacterization program executed oncomputer18 interrogates the user, using a menu display format on the computer screen, as to which functions are to be enabled, what constants are to be loaded, etc. The characterization instructions generated by the recharacterization program are then transferred from the computer through the stand to the key or lockbox, where they are stored in RAM memory.
• A set of limited recharacterization instructions forlockbox12 can alternatively be loaded fromstand16 intokey14 for later relaying by the key into the lockbox by using the PROGRAM function (discussed below in the section entitled Functions).
• The second function stand16 can perform is to retrieve data, such as lockbox access log data, from the lockbox or the key and to relay it tocomputer18. This is accomplished by positioninglockbox12 or key14 onstand16 and executing an appropriate program, this time a data retrieval program, oncomputer18.
• Stand16 can also be used for a variety of other purposes, such as for relaying diagnostic maintenance log data (discussed below in the section entitled Diagnostic Features) from the key or lockbox to the computer and for synchronizing the calendar-clock portion oflockbox CPU28 with the master calendar-clock maintained bycomputer18.
• One important feature provided bystand16 is that it allows data transfers to and from the key and lockbox components without the need to take such components back to a central control computer at the real estate board office. In large metropolitan areas, such as Houston, the local real estate board may encompass several thousand square miles. Consequently, it is highly undesirable to require that lockboxes and keys be taken back to the board office every time an exchange of data is desired. The relatively inexpensive stands of the present invention can be distributed throughout the board's territory and can be used to effect all data transfers. Desirably, most of the agency offices within the real estate board would have such a unit and several additional units would be available for portable use within the board's territory.
Operation
• To operate the lockbox system, the user first energizes, or wakes up, key14 by pushing an ON/CLEAR button onkeypad48.Beeper62 beeps to confirm that the key is energized. The key then displays the word “CODE” in the message portion ofLCD display50 in blinking form. The user then has a fixed time period, such as one minute, within which to enter a four digit personal code. As each digit of the personal code is entered, an asterisk appears inLCD display50. The asterisks maintain the privacy of the personal code while indicating the number of digits entered. If no personal code is entered within the one minute time period,key CPU52 causes the key to become deenergized, or return to sleep, again. If the four digit personal code entered by the user matches the personal code stored inkey RAM memory56, the user is prompted to select a function.
• If an improper four digit personal code is entered onkeypad48, key14 will not allow the user to select a function. The user can start over and try to enter the correct personal code. If, after four tries, the proper personal code has still not been entered,key CPU52 causes the key to enter a “personal code timeout” mode in which the key is deactivated for a ten minute period and during which it will not allow any further personal codes to be entered.
• After the four digit personal code has been successfully entered, the FUNCTION annunciator in the upper portion ofLCD display50 is made visible, together with the prompts in the lower portion of the display representing the available functions. (Key CPU52 causes the prompts corresponding to the functions that are not available, for example those functions which have been disabled, to remain invisible in LCD display50). The top left-hand most prompt in the prompt field, normally the OPEN prompt, will be blinking. It is the blinking prompt that indicates which function will be executed if the SELECT button is pressed.
• Movement of the blinking feature in the LCD prompt display is controlled by the RIGHT SCROLL and LEFT SCROLL buttons onkeypad48. The RIGHT SCROLL button causes the blinking feature to move one prompt to the right, for example, from OPEN to SHACKLE RELEASE. When the right-most prompt in a display line is blinking and the RIGHT SCROLL button is pressed, the blinking feature is moved to the left-most prompt in the following line. The LEFT SCROLL button moves the blinking feature in the opposite direction in a similar fashion.
• After the personal code has been entered successfully, it is the OPEN prompt that blinks. Consequently, to open the lockbox, which is the most common operation, the SCROLL buttons need not be operated at all. Instead, the SELECT button is simply pressed and the lockbox can be opened.
• Once the SELECT button is pressed,CPU52 causes all of the prompts to be made invisible, except the selected prompt, which is caused to stay on continuously, not blinking.
• When the personal code has been successfully entered and a function has been selected, key14 is termed “armed.” In the armed state, the key sends out a signal, termed here a characteristic interrogation pulse train, and seeks to couple with a lockbox. When the key is ultimately coupled with a lockbox, the electromagnetic pulses radiated by the key induce a voltage in the lockbox communications coil. The induction of this voltage in the lockbox signals the lockbox to wake up. The lockbox then responds by transmitting a second signal back to the key, as discussed below in the section entitled Authorization of Lockbox Functions.
• When the OPEN feature has been selected, the four letter message field in the middle ofLCD display50 displays the word “SAFE” (short for keysafe) in blinking form. (A blinking message in the message portion of the display demands an action by the user. A solid display in the message portion indicates that the key is finished with the function). When the “SAFE” message is blinking in the message portion of the display, the user has approximately ten minutes within which to engage a key with the lockbox.
• Once the key and lockbox are successfully coupled, the message display, instead of displaying the “SAFE” message in blinking form, displays a “WAIT” message in solid form. This indicates to the user that the key and lockbox are coupled and are communicating. During the “WAIT” state, various data is exchanged between the key and the lockbox and each of the microprocessors is making various decisions as to whether to authorize execution of the selected function (as described below in the section entitled Authorization of Lockbox Functions). Finally, the processors decide, either together, or one informs the other, that the selected operation can be executed.
• After the requisite exchange of data between key and lockbox has successfully been completed and the requested function has been executed, the message inkey LCD display50 changes from “WAIT” to “GOOD.” The “GOOD” message is displayed whenever any operation is successfully completed. The successful execution of the function is also confirmed audibly bybeeper62. The “GOOD” display is maintained for approximately eight seconds. The key then displays the KEYSAFE BATTERY annunciator if the lockbox battery is low (discussed below in the section entitled Battery Systems) and then returns to sleep.
• If a user arms a key and then fails to complete the selected operation with a lockbox, the key eventually goes into an error condition.Beeper62 beeps and an appropriate error code is displayed in the message display. The key then returns to sleep after displaying the error message for a predetermined time period.
• One important feature of the invention is that the key strokes necessary to request a function need not be entered while the key is coupled to the lockbox. As indicated, key14 must be held nearlockbox12 in order for the units to communicate. Although not usually a problem, this task is sometimes difficult when the lockbox is mounted in a dark or awkward location, such as on a water spigot mounted at ground level. In some embodiments, the user would need to engage the key with the lockbox in such position and then start pressing buttons onkeypad48 corresponding to the required personal code and the desired -function.
• To obviate this potential problem, the key control software allows the key to be armed in advance to request execution of a desired function. The key can then be mated momentarily with the lockbox and the handshaking signal exchanges made automatically when the lockbox detects the key's characteristic-interrogation signal. Thus, the user need not press a single key in the dark or cramped location in which the key and lockbox may be mated in order to operate the lockbox. The personal code can be entered and the desired function selected in a convenient, well-lit location, such as in a car. The agent then has a fixed period, such as ten minutes, within which to use the armed key to operate the lockbox. After this period, the key disarms itself so as to maintain system security.
• In addition to providing a convenience to the user, the ability of the key to be armed at a remote location and later coupled with the lockbox to execute a function also provides an important security benefit. That is, it allows the key to be armed away from prying eyes so as to maintain the secrecy of the user's personal code.
FUNCTIONSOpen
• To open housekey compartment20 inlockbox12, the user enters the four digit personal code onkey14, thereby causing the OPEN prompt inLCD display50 to blink. The SELECT button is then pressed and an exchange of authorization signals between the lockbox and key is begun once the units are successfully coupled. If the lockbox and key determine that the function is authorized,lockbox CPU28 allowskey compartment door24 to be opened.
• In the preferred embodiment,key compartment door24 does not pop open when the exchange of signals has been completed successfully. Instead, a press-to-open mechanism is provided on the door. After the appropriate signals have been exchanged, the user pressesdoor24 inwardly and then releases. The door then pops open to reveal the contents ofcompartment20.
• If the user does not open the press-to-open door within a predetermined period of time, such as sixty seconds, the lockbox reverts to its powered down, locked state.
• In order to conserve lockbox battery power, keycompartment unlocking solenoids36 are not energized until the user presses the press-to-open door. To effect this power savings,lockbox12 is provided with amicroswitch42 connected in key compartmentsolenoid drive circuit40 so that whendoor24 is pressed in, the microswitch is engaged and closed. Whendoor24 is pressed in,CPU28 detects the closure ofmicroswitch42 and causes drivecircuit40 to then apply energy tokey compartment solenoids36 for a brief period. The solenoids retract, thereby unlockingdoor24. The user then releases the door and it pops open under the influence of a spring. The solenoids are thus not energized until the user is actually ready to open the door. (The solenoids are arranged inlockbox12 so that the inward pushing movement ofkey compartment door24 is allowed even when the solenoids are in their locked state).
• Aftermicroswitch42 is reopened by the door popping open,lockbox CPU28 waits approximately 0.25 seconds and then causes drivecircuit40 to deenergize the solenoids. It has been found that in a typical opening, the locking solenoids are energized for less than 0.5 seconds. After deenergizing the solenoids, the lockbox returns to its sleeping state.
• Ifdoor24 is pressed in but is not released for more than 1.25 seconds,solenoids36 are deenergized to secure the lockbox and the lockbox returns to sleep.
• In the preferred embodiment,key compartment door24 is provided with two solenoids to enhance lockbox security. Each solenoid has a spring loaded plunger. If only a single solenoid were used, the solenoid could be dislodged momentarily from its locking position by a sharp blow to the lockbox. The shock could propel the solenoid plunger momentarily to its retracted state, allowingdoor24 to be opened.
• In the preferred embodiment, two solenoids are used and are disposed so that their plungers travel in opposite directions. If the lockbox is sharply rapped so as to propel one solenoid plunger to its unlocked position, the other solenoid plunger is propelled to its locked position.
• In an alternative system using a single solenoid, a rotary solenoid could be used. However, such an arrangement is less efficient and more expensive than the present system and also requires additional latching components.
Shackle Release
• Theshackle22 or mounting bracket which secureslockbox12 to a structure is, in the preferred embodiment, released on command from a key. By allowing real estate agents to administer lockboxes, rather than just real estate board employees, administration of large lockbox systems is facilitated.
• To releaselockbox shackle22, the user enters the four digit personal code into the key and moves the blinking feature in the prompt field to SHACKLE RELEASE. The SELECT button is then pressed and a “SAFE” message begins blinking inkey LCD display50. After the lockbox and key are coupled, these units exchange signals and, if these units decide that a shackle release is authorized, a “GOOD” message appears inLCD display50 and a shackle release is permitted.
• In the preferred embodiment of the invention, the SHACKLE RELEASE function openslockbox door24. Actual release of the shackle is then effected by movement of a press-to-release shackle locking stem162 (which is unlocked by shackle locking solenoids38), which in turn moves ashackle locking bar148 out of engagement with the shackle. Like the key compartment door arrangement, the shackle locking system also uses a pair of reciprocally mounted solenoids to lock the shackle so as to enhance lockbox security.
Change Personal Code
• When the user desires to change the four digit personal code, the CHANGE PERSONAL CODE function is used. The key is activated by the usual sequence of entering the four digit personal code and then moving the blinking feature in the prompt field until the CHANGE PERSONAL CODE prompt is blinking. When the SELECT button is pressed, the message display displays “NEW.” The user then keys in the new four digit personal code that is to be substituted for the old code. Each time a digit of the new code is entered, an asterisk appears in the message portion ofdisplay50. After all four digits have been entered, the “NEW” message is displayed again. The user then reenters the new code. By this redundant technique,key CPU52 double checks the new personal code to insure that the user did not inadvertantly press a wrong key and thus enter a new personal code that was not intended and consequently would not be remembered.
• After the successful entry of the new four digit personal code twice, the message display portion ofLCD display50 indicates “GOOD” to confirm that the operation has been completed satisfactorily.
Controller
• As discussed earlier, a stand is used to exchange data and characterization instructions between the key and the computer. One way in which data can be exchanged between these units is simply to lay the sleeping key on the stand and press the ON/CLEAR button. The stand then couples electromagnetically to the energized key and allows the key to communicate with the computer. However, for security reasons, it is desirable that the computer not be allowed to perform the full range of possible functions on the key when the key is activated in this manner. An unauthorized user of a key could take the key and reprogram it if no further precautions were taken. Accordingly, it is desirable to limit the functions that the key and computer can cooperate to perform when the key is merely energized by the ON/CLEAR button to a narrow group of functions, such as running diagnostic routines and resetting the master software switch (discussed below). Thus the key will not permit new characterization instructions to be loaded.
• In order forcomputer18 to be allowed to perform its full complement of functions on the key, the key must be activated in the CONTROLLER mode by an authorized user. To do this, the user enters the four digit personal code and moves the blinking feature in the prompt field to CONTROLLER. When the SELECT button is pressed, the key permits the computer to freely read from and write to the key within the limits set by ownership of the key (i.e. a computer cannot reprogram a key if the key belongs to a different board).
• Arming the key in the CONTROLLER mode is the only instance in which the key does not send out its characteristic interrogation pulse train. Instead, the key listens for data or instructions relayed from the stand.
File Mark
• Skipping ahead in the key's prompt field somewhat, the FILE MARK function is selected to put a mark in the access log maintained by the lockbox. As noted, the illustrative access log maintained inRAM memory30 oflockbox12 contains data relating to the last100 lockbox operations. Oftentimes, however, not all100 past operations are of interest. For example, the supervising real estate board or agency may only be interested in operations over a certain period of time. To facilitate this function, the lockbox access log can be marked with file marks. The log can then be read in its entirety, or just from the last file mark to the end. By this technique, only the data of interest need be reviewed.
• The FILE MARK function is useful when a real estate agency or board is interested in monitoring the access to a home during a specific period, as for example, during a weekend that the house is advertised in the newspaper. In such case, the listing agent could enter a file mark in the lockbox access log on a Friday evening. (Only the listing agent, or the listing agent's broker or board, is permitted to executed a FILE MARK function on a lockbox). An agent could then return the following Monday morning and recover only those entries in the access log made since the log was marked by using the READ FILE MARK function.
• If a lockbox is moved from one house to another, a file mark can be used to indicate in the access log when the lockbox was moved. In one form of the invention, a file mark is entered in the access log automatically whenever the shackle is released. Data can then be selectively recovered from the access log so that only operations logged at the new location are recovered.
• The entry that is actually recorded in the access log by a FILE MARK function is the same as any other logged function, but the log indicates that it is a FILE MARK function, rather than an OPEN, SHACKLE RELEASE, etc. The lockbox also records the other data usually stored in the access log, such as the identity of the user who executed the FILE MARK function, the date and time, etc.
Read
• When the READ function is selected,lockbox CPU28 causes all of the entries stored in the lockbox access log to be transmitted to the requesting key by relaying the access log data via the unit' coupled communications coils. The key stores this received information in a portion of itsRAM memory56 dedicated to this purpose.
• The portion ofkey RAM memory56 dedicated to storing lockbox access log data can be larger or smaller than the portion of memory in the lockbox dedicated to this task. Typically, the dedicated key memory is at least as large as the dedicated lockbox memory (i.e. large enough to hold at least100 access entries). A key can thus read several lockbox access logs, provided the total number of access log entries read does not exceed the key's capacity.
• If a user attempts to read a lockbox that has more access log entries than the key has memory, the key will display a corresponding error message and will not execute the READ function.
• Successful execution of the READ function does not cause the access log data in the lockbox to be erased. Instead, the data persists and is eventually overwritten by the lockbox itself, beginning when the one hundred and first log entry overwrites the first log entry. When the lockbox is later reinitialized and moved to a new listing, the access log data is dumped to a stand and the roll flag and pointer are reset to their initial states.
• As noted earlier, if any lockbox access log data is stored in the key, the READ annunciator will be made visible when the key is awakened by the ON/CLEAR button so as to remind the user that one or more reads are stored in the key.
Read File Mark
• READ FILE MARK is identical to the basic READ function except that only the lockbox access log entries since the last file mark are read.
Read NN
• Lockbox CPU28 maintains a lockbox access count inlockbox RAM memory30 that indicates the number of OPEN, SBA and SIGNATURE functions that have been executed by the lockbox since it was reinitialized for that particular listing. In the preferred embodiment, this count is stored as a single eight bit byte and thus can count up to 255 accesses. When the READ NN function is selected and executed,lockbox CPU28 transmits this lockbox access count to the key where it is displayed to the user in the message portion ofLCD display50.
• This READ NN function allows the user to monitor listing activity at a glance, without downloading data from the key to a stand at a remote location. This function also allows a user to monitor lockbox usage so that the maximum memory capacity of the lockbox access log will not be exceeded and old data overwritten. For example, if the lockbox access log can store 100 entries and the user determines, by using the READ NN function, that there have been90 accesses to the listing, the user may choose to then dump the contents of the log into the key for later relaying to a computer through a stand. By such operation, the old data in lockbox access log is preserved in the computer and up to 100 new entries can then be logged in the lockbox.
Clear Memory
• The CLEAR MEMORY function clears both the portion ofkey RAM memory56 dedicated to storing lockbox access log data and the portion of the key RAM memory dedicated to storing lockbox characterization instructions.
• The lockbox access log data normally stays inkey RAM memory56 until the key is coupled to a stand and the data dumped to a computer. If, for some reason, the user does not want to preserve this data he can, instead of dumping it out to the computer, simply select the CLEAR MEMORY function and erase it.
• The lockbox characterization instructions stored inkey RAM memory56 can variously stay in the key memory only until loaded into a lockbox or they can stay indefinitely, depending on the nature of the instructions (discussed below in the discussion of the PROGRAM function). If, for some reason, the user does not wish to preserve this data, the CLEAR MEMORY function can be selected to erase it.
Signature
• The access log maintained in the lockbox is useful for reasons other than determining, for security purposes, who opened the lockbox. It is also desirable, for management information purposes, to be able to determine the identity of persons who entered the house without opening the lockbox.
• Real estate agents often visit newly listed houses in large tour groups. The identity of the one agent in the group that opens the lockbox is of course entered in the access log. The identity of the other agents in the group could also be logged in the access log if they were also to open the lockbox. However, the OPEN function draws a considerable amount of power from the battery. Consequently, it is desirable to be able to log the identity of agents without requiring them to open the lockbox. The SIGNATURE function performs this task.
• Agents who select the SIGNATURE function can engage their keys with the lockbox and have their identities logged in the access log. The lockbox treats this function as an OPEN operation, but omits the final step of energizing the solenoids. Consequently, the power drain is negligible. By use of this function, the system is better able to maintain detailed information on visitors to a listed property.
• The SIGNATURE mode has applications beyond real estate lockboxes. For example, a night watchman at an industrial complex could-use the SIGNATURE function to log the date and time of his visits to the various locks around the complex without opening any such locks. A record could thus be maintained of the surveillance activity at various sites around the premises.
Shown by Arrangement
• SHOWN BY ARRANGEMENT (SBA) is a function that allows a listing agent to restrict which other agents are allowed access to certain listed properties.
• Certain homeowners do not wish every agent in a real estate board to be able to gain access to their homes. They have placed their trust in one listing agent and want only agents authorized by that agent to show the house. However, it is impractical for the listing agent to be present at each such showing. The Shown By Arrangement feature of the present invention allows the listing agent to program the lockbox to require that a second code, an SBA code, be entered before access to the house key is granted.
• The SBA function is activated by specifying a desired four digit SBA code in the lockbox characterization instructions. If no SBA code is specified, a default value of 0000 is stored. When an agent tries to access a lockbox for which a non-zero SBA code has been specified, he or she must do so by first selecting the SBA function. When the key is so armed in the SBA mode, the agent is then prompted to select one of two functions from the prompt field: OPEN or CHANGE SBA.
• If the OPEN function is selected, a “SBA” message is displayed in blinking form in the LCD display, prompting the agent to enter the SBA number. The agent then enters the four digit SBA number and corresponding asterisks appear in the LCD display. After the code is entered, it is transmitted to the lockbox with the request to execute the OPEN function. If the SBA code entered matches the SBA code stored, and if other authorization criteria discussed below are met, the function is executed. If the SBA code entered does not match the SBA code stored, the function is immediately denied.
• The second option after arming the key in the SBA mode is to change the SBA number. (When the key is armed in the SBA mode, a CHANGE prefix is made visible inLCD display50 next to the SBA prompt to permit selection of the CHANGE SBA function). This option can only be executed by the listing agent, the listing agent's broker or the listing agent's board. The lockbox checks that the identity of the key corresponds to one of these entities by comparing key identifying data sent from the key with the lockbox identifying data stored inlockbox RAM30.
• When the CHANGE SBA function is selected, a “NEW” message appears in thekey LCD display50 in blinking form, requesting the user to enter the new SBA number. Again, like changing the four digit personal code, this new SBA number must be entered twice in order for the change to be effected.
Program
• The PROGRAM function transmits a set of limited characterization instructions from a key to a lockbox to effect a reprogramming of the lockbox in the field.Key CPU52 will not make visible the PROGRAM prompt nor permit selection of the PROGRAM function unless the CPU has earlier determined that the key contains a set of limited lockbox characterization instructions waiting to be downloaded into a lockbox.
• The lockbox programs that can be loaded into the key from the computer in the exemplary embodiment can be of two types: Specific Update and Blanket Update. Specific Update is used when a set of lockbox characterization instructions is destined for one particular lockbox, identified by that lockbox's serial number. Once the program has been downloaded to that lockbox,key CPU52 automatically erases it fromkey RAM memory56. Specific Update is generally used to change a lockbox's Daily Disable times and to set data switches enabling Privacy Read and Privacy Shackle Release (discussed below in the section entitled Programmable Lockbox Options).
• Blanket Update, in contrast, is used when a set of lockbox characterization instructions is destined for a group of lockboxes. Downloading the instructions to a lockbox does not erase the instructions fromkey RAM56. Instead, the instructions persist in the key until erased by the CLEAR MEMORY key.
• Blanket Update is generally used to recharacterize lockbox instructions on an agency- or board-wise basis. Blanket Updates generally fall into two classes: those that update the lockout list and those that reprogram the identity of the lockbox's listing agent.
• Both Specific and Blanket Updates are transferred to the lockbox by using the PROGRAM function. The difference between the two is an update type data string included with the key programming instructions which indicates whether the update is a Specific Update or a Blanket Update, and, if it is a Blanket Update, whether it updates the lockout list-or the listing agent.
• In the preferred embodiment, the programming of the lockbox by the key in the field is limited so that only certain of the lockbox characterization instructions can be reprogrammed by the key. In the exemplary embodiment only the Lockout List data, the SBA number, the Daily Disable times and the listing agent identity can be reprogrammed in this manner, as is indicated inFIG. 13. The other data, such as the house, board and agency identification data and the lockbox access codes, cannot be changed by the key. To change this restricted data, the illustrated lockbox must be returned to a stand for reprogramming directly by a computer.
• The memory map ofFIG. 13 illustrates that separate portions ofkey RAM memory56 are dedicated to storing lockbox characterization instructions and copies of lockbox access logs. In other embodiments, a single portion ofkey RAM memory56 can be shared for these purposes.
PROGRAMMABLE KEY OPTIONS
• The instructions needed to implement the following key options are provided with the key control software stored inkey ROM64. These options are then individually enabled or disabled by setting appropriate enable/disable bits stored inkey RAM56 with the key characterization instructions.
Key Expiration Date
• To enhance security of the system, some or all ofkeys14 can be programmed to “expire” (become disabled) after a predetermined number of days. By this technique, keys that are lost or stolen lose their utility in a relatively short time.
• InRAM memory56 ofkey14 is data corresponding to a julian expiration date on which the key is to expire. Before any functions requested by the key are authorized,key CPU52 first compares this expiration date with data received from the calendar-clock portion oflockbox CPU28 indicating the current date. Ifkey CPU52 determines that its expiration date has passed, the requested function is denied. A signal is sent tolockbox12 informinglockbox CPU28 of the expired key for logging in the lockbox's diagnostic maintenance log (discussed below in the section entitled Diagnostic Features). A corresponding entry is made in the key's diagnostic maintenance log. The key then displays an error message indicating an expired key in the message portion ofkey LCD display50. After the message has been displayed for a predetermined period of time, the key reverts to its sleeping state.
• This expiration date feature significantly enhances system security without imposing any significant burden on users of the system. Expired keys can be “rejuvenated” by an appropriate authority, usually the supervising real estate board, by simply loading a new expiration date intokey RAM56 via a stand.
• The present expiration feature also offers the supervising board and the individual users considerable operational flexibility. For example, the board can set a key to expire on any desired date. A key can thus be programmed to expire in a day, a week, a year or never, in increments of one day. (To program the key to never expire, this function is simply not enabled). This flexibility also enables the board to set different expiration dates for different keys. For example, it may wish the keys of new agents to require rejuvenation every two weeks, those of established agents to require rejuvenation every two months and those of brokers to require rejuvenation only every two years. The expiration dates of the various keys can also readily be staggered so that all the keys in the system will not need to be rejuvenated on the same day. The system offers flexibility to users in that a key can be rejuvenated before it expires. A key owner can thus rejuvenate a key at a time when it is convenient, rather than at a time dictated by the lockbox owner.
Key Deactivation
• Key14 can selectively be deactivated to disable its further use by setting an appropriate disable bit inkey RAM56. This is useful when, for example, a board or an agency wishes to store unused keys. After being deactivated, key14 must be reinitialized with new characterization instructions from the board or other supervising authority before it can be used again.
PROGRAMMABLE LOCKBOX OPTIONS
• The instructions needed to implement the following lockbox options are provided with the lockbox control software stored inlockbox ROM44. These options are then individually enabled or disabled by setting corresponding enable/disable bits stored inlockbox RAM30 with the lockbox characterization instructions.
Daily Lockbox Disable
• Oftentimes, homes listed by real estate agents are not vacant. The current owner may still be residing in the house and may not welcome visitors at certain hours. For example, a homeowner may work in the evenings and sleep during the days and consequently wish that his house not be shown between the hours of 7:00 a.m. and 3:00 p.m. To accommodate such homeowners,CPU28 oflockbox12 can run a software routine, stored inlockbox ROM memory44, that disables the lockbox from opening during certain hours of the day. The daily lockbox disable software routine operates in conjunction with the calendar-clock portion oflockbox CPU28 and with programmable time data indicating the desired beginning and end times of the daily lockbox disable period. These beginning and end times are loaded intolockbox RAM memory30 with the lockbox characterization instructions and can be loaded by an appropriately programmedkey14.
• In the preferred embodiment of the present invention,lockbox CPU28 is programmed to correct its internal calendar-clock data automatically to account for time changes brought on by daylight savings time so as to maintain the desired daily disable times. Similarly, the calendar-clock portion oflockbox CPU28 also corrects itself for leap years.
Lockbox Disable On Removal
• After a real estate agent has released a lock-box shackle, the lockbox could normally be reinstalled on another house. Before such installation, however, the lockbox should be be reinitialized and loaded with a variety of new characterization instructions identifying the new listing, the listing agent, the listing agency, etc. In certain embodiments, this recharacterization could be accomplished by loading a key14 with all of the new instructions and loading the lockbox from the key using the PROGRAM function.
• In most systems, however, this field reprogramming procedure is undesirable. It does not guarantee that the characterization instructions loaded bycomputer18 intokey14 are actually transferred into the lockbox. More importantly, it does not guarantee that the access log data stored in the lockbox is recovered and relayed back to the computer for archival purposes.
• In systems where data integrity is important, it is desirable that the lockbox be read and programmed directly by the computer without the use of an intermediate key. To insure that this is done, a Lockbox Disable On Removal feature is selectably provided.
• When the Lockbox Disable On Removal feature is enabled by appropriate bits in the lockbox characterization instructions, the lockbox becomes disabled when the shackle is released. In this disabled state, the lockbox cannot be operated nor can it be reprogrammed from the key. It must be returned to a stand at a board or agency office for reprogramming. By requiring the lockbox be returned for reprogramming, the access log can be reliably read for archival purposes, thereby insuring the integrity of the board's lockbox database.
Lockout List
• In certain instances, it may be desirable to lock out certain agents, or agents from certain agencies, and thereby deny them access to a listed property. In the preferred embodiment,RAM memory30 oflockbox12 contains a list of key identification data that, although the keys so identified may otherwise be authorized, are to be locked out. The identification data received from the accessing key is compared against this list bylockbox CPU28. If the accessing key's identification data corresponds with data found in this list,lockbox12 will refuse to execute any lockbox functions requested by the key.
• In the preferred embodiment, there are three types of lockouts. The first type of lockout identifies specific agents that are to be locked out. The second type of lockout identifies specific agencies that are to be locked out.
• The third type of lockout identifies a specific agency that is to be allowed access to the house key. Agents from all other agencies are to be locked out. By this third type of lockout, a house can be exclusively listed by a single agency so that only agents from that agency can show the house.
• Each of these lockout functions is implemented by certain enabling data stored inlockbox RAM memory30 with the lockbox characterization instructions. If any of these functions is implemented, the characterization instructions further include data specifying the identities of the agents or agencies who are to be locked out.
Lockout with Key Disable
• As a further option on the lockout list function,lockbox CPU28 can be programmed to disable certain locked-out keys that may attempt to execute a function on the lockbox. In the exemplary embodiment,lockbox CPU28 responds to each such preidentified key with a special signal that instructskey CPU52 to alter the key's four digit personal code inkey RAM memory56 by replacing certain digits of this code with hexadecimal digits (A-F) which are not included on the key'skeypad48. With the personal code so altered, the user can no longer arm the key for use. The personal code can only be made usable again by reprogramming the key, which operation is usually only performed by the supervising real estate board.
Updating Lockout Lists
• It will be recognized that the lockout list data stored in each lockbox may need to be updated frequently in order to be effective in locking out undesired keys. In one form of the invention, key14 has a portion of itsRAM memory56 dedicated to storing a lockout list. Stored with this list is a date indicating the timeliness of the lockout list data. A date is also stored with the lockout list data stored inlockbox12 indicating its timeliness. Whenever key14 andlockbox12 communicate, these dates are compared bykey CPU52 orlockbox CPU28. If it is determined that the lockout list data stored inkey14 is “fresher” than that stored inlockbox12, the key's lockout list data, including the date data, is transferred tolockbox RAM memory30 where it overwrites the “stale” lockout list data previously stored there. If it is determined that the lockout list data stored inlockbox list12 is “fresher” than that stored inkey14, the lockbox's lockout list data, including the date data, is transferred tokey RAM56 where it overwrites the “stale” lockout list data previously stored there. By this technique, one unit updates the other so that each has the newer lockout list data.
Privacy Read
• Some listing agents, especially those who list expensive homes, may wish to prevent others from retrieving the lockbox access logs recorded in their lockboxes. These logs may reveal the identities of the agents within the real estate board whose clientele can afford expensive homes. This is useful information that the listing agent may not wish to share with other agents.
• In order to maintain the privacy of this information, the lockboxes of the present invention can be programmed, by an appropriate bit in the lockbox characterization instructions, to allow only the listing agent, or that agent's broker or board, to retrieve the lockbox access log. If this enable bit is set,lockbox CPU28 compares the identification data received from the key with its own lockbox identification data before allowing an otherwise authorized READ operation to be performed. Access to the lockbox access log can thereby be limited to this authorized class of keys.
• Privacy Shackle Release It is generally desirable to restrict execution of the SHACKLE RELEASE function to the listing agent, or to that agent's broker or board. To restrict execution of the SHACKLE RELEASE function in this manner, a Privacy Shackle Release function is provided. If this function is enabled,lockbox CPU28 compares the identification data received from the key with its own lockbox identification data before allowing a SHACKLE RELEASE function to be performed.
Lockbox Deactivation
• Lockbox12 can selectively be deactivated to disable its further use by setting an appropriate disable bit inlockbox RAM30. After being deactivated,lockbox12 must be reinitialized with new characterization instructions from the board or other supervising authority before it can be used again.
DIAGNOSTIC FEATURESPower-On Diagnostics
• As soon as key14 is awakened by pressing the ON/CLEAR button, a set of diagnostic routines is run to confirm proper operation of the key.
• As a first check,key CPU52 determines whether the “master software switch” is off. The master software switch is a flag inkey RAM memory56 that indicates whether the key's characterization instructions are corrupted. This switch is turned off every time a process of critical loading characterization instructions from a computer into the key is begun. The switch is not turned back on again until the transfer of instructions is completed without error. If, for example, the key is removed fromstand16 before the transfer is completed, the characterization instructions inkey RAM memory56 will be incomplete.Key CPU52 recognizes this data corruption by noting that the master software switch is still off and accordingly prevents the key from attempting any operations until the characterization instructions are loaded correctly. (Provision is made for reloading new characterization instructions from a properly authorized computer through a stand even when the master software switch is off).
• As a second check,key CPU52 determines whether there is any button onkeypad48 that is stuck in the down position.
• As a third check,key CPU52 determines whether the key is in personal code timeout mode. Personal code timeout mode is the ten minute period following four unsuccessful entries of the personal code.
• As a fourth check,key CPU52 performs a non-destructive test onkey RAM memory56 to determine if it is malfunctioning.
• If any of these four error conditions is detected, a corresponding error message is presented in the message ofLCD display50 for a five second period and the key then returns to sleep.
• If none of the error conditions is detected, the key then examines the status of the key battery. If it needs to be replaced,key CPU52 makes visible the KEY BATTERY annunciator for the remainder of the key's operations. If the key battery count (discussed below) is equal to zero,CPU52causes LCD display50 to display the message “DEAD” for a predetermined period of time and then go to sleep.
• If the diagnostic tests are run successfully, the key allows the user to proceed and enter the four digit personal code, etc.
Error Messages
• The message display portion of theLCD display50 can indicate up to 100 errors by displaying messages ER00 through ER99. The error codes are very finely detailed so that a user can determine quite accurately the nature of a problem by reference to the two digit code. Selected error conditions displayed in this manner include pushing a wrong button, dead battery, wrong personal code, key in personal code timeout mode, keyboard button stuck, master software switch off, etc.
Diagnostic Maintenance Log
• Occasionally, a vendor or manufacturer may receive reports that a lockbox or key is malfunctioning. To aid in investigation of such reports, the lockboxes and keys of the present invention each have a portion of their RAM memories dedicated to storing detailed diagnostic information. In the preferred embodiment, detailed information on the last ten events noted by the lockbox or key microprocessor is stored in this “diagnostic maintenance log.” Each diagnostic maintenance log entry identifies the events noted and the key or lockbox unit's response.
• The diagnostic maintenance log entry of an exemplary OPEN operation in the key might be as follows. The key is energized by the ON/CLEAR button. If one of the Power-On diagnostics is failed, a corresponding entry is made in the diagnostic maintenance log. Assuming the Power-On Diagnostics are run successfully, the user is allowed to enter the four digit personal code. If the wrong code is entered or if no code is entered within the ten second time period, a corresponding entry is made in the maintenance log. Assuming the personal code is correctly entered, the user is next prompted to select a function. Again, if an error is made by the user in selecting a function or if the function selected is denied by the system, a corresponding entry is made in the maintenance log. This process of logging any error condition continues until the key returns to sleep.
• Although not recited in the foregoing example, it should be noted that an interruption in the communications between a lockbox and key is an event that is always recorded as an entry in the diagnostic maintenance log.
• Depending upon the requirements of a particular application, each CPU could be programmed to record data on all events, or only on those events that prevent the requested operation from being executed.
• It will be noted that the lockbox access and diagnostic maintenance logs of the present invention serve two entirely different purposes. The lockbox access log serves as a record, for legal or management information purposes, of a narrow range of lockbox operations. The lockbox access log only logs OPEN, SBA, SHACKLE RELEASE, SIGNATURE and FILE MARK functions. It logs both successful and unsuccessful OPEN, SBA, SHACKLE RELEASE and SIGNATURE functions, but only logs FILE MARK functions if they are successful. If an unsuccessful function is logged, no diagnostic data indicating the reason for the failure is recorded. With each of these access log entries, however, the lockbox logs a variety of ancillary data, such as the date and time of the operation and the identity of the key requesting the operation.
• The diagnostic maintenance log, in contrast, serves only as a diagnostic tool. It serves in this capacity for all lockbox or key operations, not just those four which are of concern to the lockbox access log. For each operation, it stores detailed diagnostic information. However, no time, date or identification data is logged.
• Upon reports of a malfunctioning lockbox or key, the corresponding diagnostic maintenance log can be retrieved, either by sending the malfunctioning unit to the board for coupling to the board computer or by coupling the unit to the board computer through astand16. This data can then be evaluated to determine the cause of the malfunction.
Remote Testing
• In addition to retrieving diagnostic maintenance log data from keysafes and locks for coupling to a computer, stand16 further serves a diagnostic function by enabling a computer to conduct detailed testing on a malfunctioning lockbox or key unit. A lockbox or key that is malfunctioning can be put on a stand and the central board office computer called. The central computer can then run a collection of diagnostic routines and indicate to the user the cause of the problem. If the board's central computer is not able to diagnose the problem, the vendor or supplier of the equipment can run exhaustive diagnostic routines directly from its office to the unit on the stand at the remote location.
AUTHORIZATION OF LOCKBOX OPERATIONS
• The determination of whether a key is authorized to operate a lockbox is made by comparing certain strings of data exchanged between the lockbox and key. An operation is only authorized if these data strings correspond to a specified degree. This process is explained in more detail below.
• In the preferred embodiment, the exchange of signals between the key and lockbox comprises a multipart handshake. First, key14 sends a first, interrogation signal tolockbox12 to cause the lockbox to wake up from its sleeping state.Lockbox12 responds by sending a second signal back to the key. This second signal includes lockbox battery condition data and date data (provided by the calendar-clock portion of CPU28).
• Upon receiving this data,key CPU52 compares the received date data with the key expiration date stored inkey RAM memory56, as discussed earlier. If it is determined that the key is not expired,key CPU52 then sendslockbox CPU28 data identifying the key by agent, agency and board so that the lockbox can determine whether the requested function can be executed on the basis of an ownership match between the lockbox and key.Lockbox12 has corresponding identification data, identifying its listing agent, agency and board, stored in itsRAM memory30. In order forlockbox12 to authorize execution of the requested function on the basis of an ownership match,lockbox CPU28 compares the key identification data received from the key with its own lockbox identification data to determine whether they correspond to a required degree. The degree of correspondence required between these groups of data before an operation is authorized is specified by “permission codes” stored in the key and sent to the lockbox with the key identification data.
Permission Codes
• At one extreme, the permission codes may require only that the lockbox and key identification data indicate that the lockbox and key are assigned to the same real estate board in order for the lockbox to authorize the requested operation. At the other extreme, the permission codes may specify that even if the lockbox and key are assigned to the same board, agency and agent, the lockbox will still not authorize the requested function. In between these extremes, the permission codes may specify that the corresponding elements of board and agency identification data match, or; that the corresponding elements of board, agency and agent identification data match, before the lockbox will authorize a requested operation.
• Three different permission codes are stored inkey RAM memory56 corresponding to three groups of lockbox operations. The first permission code specifies the degree of match required between the lockbox and the key identification data before an OPEN, SBA, change SBA or FILE MARK function will be authorized. The second permission code specifies the degree of match required between the lockbox and key identification data before the SHACKLE RELEASE function will be authorized. The third permission code specifies the degree of match required between the lockbox and key identification data before any of the READ functions will be authorized. (The remaining functions do not depend on permission codes for authorization. CHANGE PERSONAL CODE, CLEAR MEMORY and CONTROLLER are functions executed by the key alone, not in cooperation with a lockbox. SIGNATURE does not require any ownership match for execution. PROGRAM generally cannot be executed unless there is a match between the owner of the computer that loaded the programming instructions into the key and the owner of the lockbox.)
• Each permission code can assume one of four values as follows:
• 4 Disabled
• 3 Requires board, agency and agent match
• 2 Requires board and agency match
• 1 Requires only board match
• Iflockbox CPU28 finds the requisite match between the lockbox and key identification data, the lockbox authorizes and executes the requested function. If the lockbox CPU does not find the requisite match, the system then examines whether the function might be authorized based on an “access code” match.
Access Codes
• If the requested function is OPEN or SBA, key14 may authorize the function based on an access code match.
• Bothlockbox14 and key12 have at least one access code stored in their respective RAM memories. (In one form of the invention, up to fifteen access codes can be stored in each unit). The access codes stored in the lockbox are each three bytes long. A two byte field identifies the real estate board. A one byte field is arbitrary. The access codes stored in the key also contain a two byte field identifying the board and a one byte arbitrary field. The key access codes, however, each additionally contain an expiration date field. If the requested function is an OPEN or SBA function and if the function was not authorized by a permission-code specified ownership match, the lockbox transmits its access codes to the key for evaluation bykey CPU52.
• After receiving the lockbox access codes,key CPU52 compares each of the lockbox access codes with each of the key access codes stored inkey RAM56. Ifkey CPU52 finds a match, it then compares the expiration date associated with the matching key access code with the date data received earlier from the lockbox to determine whether the key access code involved in the match is nonexpired. If the code is nonexpired, the key sends the lockbox a signal instructing the lockbox to execute the requested OPEN or SBA function.
• If none of the key access codes matches any of the lockbox access codes, or if only expired key access codes match lockbox access codes, the key sends the lockbox a signal instructing the lockbox not to execute the requested OPEN or SBA function.
• Summarizing the procedure by which a function is authorized, if the requested function requires a permission code-specified ownership match and such match is found, the lockbox authorizes the requested function. If the requested function is an OPEN or an SBA and if the permission code-specified match is not found, the key can nonetheless authorize the function if any of the lockbox access codes match any of the nonexpired key access codes.
• It should be noted that the particular function authorization process described above was adopted because it minimizes the amount of data transmitted between the lockbox and key units and because it made the most efficient use of the processing and memory capabilities of the respective units. However, the elements of data exchanged and the distribution of the decision making tasks between the two CPUs could readily be altered to meet the requirements of other applications.
Segmentation/Regionalization
• The access code system of the present invention provides several capabilities that have been difficult or impossible to implement in prior art lockbox systems. One such capability is board segmentation and regionalization.
• In a typical system, the arbitrary byte included in the lockbox and key access codes is used to segment or regionalize the properties listed by a real estate board into a variety of classes. For example, a board may deal in both residential and commercial properties, but not want residential agents to gain access to commercial listings and vice versa. In this case, the arbitrary byte in the lockbox access codes of the lockboxes installed on commercial properties could be set to “1” and the arbitrary byte in the lockbox access codes of lockboxes installed on residential properties could be set to “2.” The keys of commercial agents would then be programmed to have an access code terminating in “1,” while the keys of residential agents would be programmed to have an access code terminating in “2.” With the access codes so set, residential agents would be prevented from gaining access to commercial properties and vice versa.
Inter-Board Cooperation
• In addition to enabling real estate boards to segment and regionalize their listings, the access code system of the present invention also enables real estate boards to cooperate in the sales of properties. For example, Board A may wish to allow all agents from neighboring Board B to have access to a lockbox on a particular house within Board A territory in order to expedite its sale. To do this, Board A would add to this lockbox's access code list an additional access code comprised of two bytes identifying Board B, together with the one byte arbitrary field that is in general use by Board B. By so doing, Board A enables all agents from Board B to open the lockbox with their existing Board B keys.
• Similarly, an agent (c) from Board C may wish to show a client houses listed for sale in neighboring Board D. To do this, agent (c) would call Board D and request that it load an access code into agent (c)'s key that matches the access code (or codes) resident in the Board D lockboxes to which agent (c) seeks access. (A board can only load a key with key access codes having that board's identifying two byte field). The loading of these access codes could be done by Board D's computer over telephone lines into agent (c)'s key via a stand, regardless of the distance between Boards C and D. Board D would doubtless also append an expiration date to the codes loaded into agent (c)'s key so that agent (c) could only access the properties in Board D for a limited period, such as a day or two.
Additional Information on Permission Codes
• Like the access code system described above, the permission code system also gives the present invention capabilities that were difficult or impossible to implement in prior art lockbox systems. For example, the permission code system enables keys to be delegated different capabilities corresponding to the needs and privileges of different users.
• As noted, each key is programmed with permission levels for three different classes of functions: OPEN/SBA, SHACKLE RELEASE and READ. In operation, the permission levels indicate the degree of ownership match required between a key and lockbox before the two units can cooperate to execute a function.
• The different permission codes in a key are assigned independently of one another, so that a key can have one permission code for certain functions and different permission codes for other functions. This feature allows boards and agencies to vary the capabilities of their keys simply by reprogramming the permission codes stored with the key characterization instructions. Such specialized keys have several applications. For example, an agency may wish to hire a courier to visit various houses listed by the agency to retrieve the lockbox access logs. However, the agency may not want the courier to have access to the key compartments of any of these lockboxes. To limit the courier's capabilities in this manner, the agency puts the key in the stand and sets the permission codes for OPEN/SBA and SHACKLE RELEASE to 4. A permission code of 4 prevents the function from being executed, regardless of the degree of ownership match between the lockbox and key. The READ permission level is set to 2, which allows the key to read the lockboxes on all the houses listed by the agency. The courier can then go and retrieve data from all these lockboxes and yet be unable to gain access to any of the house keys.
• As far as the permission levels are concerned, there is no distinction made between listing agents and nonlisting agents. A permission code of 3 is generally assigned to each. However, listing agents can perform significantly more functions at a lockbox than a regular agent. For example, listing agents can change the Shown By Arrangement code and can execute Privacy Reads. These privileges, however, are not granted by reference to permission codes inkey RAM56. Instead, such restricted functions are authorized only whenCPU28 orCPU52 has confirmed that the key requesting execution of the function is owned by the listing agent associated with the lockbox (or that agent's broker or board). If no such match is found, the key owner is refused authorization to execute the listing agent functions.
Industrial Applications of Permission Codes
• The permission code system of the present invention has applications in the industrial security market as well as in the real estate lockbox field. An industrial site can be tiered in a manner analogous to the agent, agency and board levels used in lockboxes. For example, an industrial site could be tiered into employee, building master and site master levels. The employees of a company could be assigned permission codes of 3, allowing them to unlock only the doors for which they are the responsible employees. Building security guards could be assigned permission codes of 2, allowing them to unlock all doors in the particular buildings for which they are responsible. Master security guards could be assigned permission codes of 1, allowing them to unlock all doors on the site.
Permission Codes and Computers
• The permission code system of the present invention is also used withcomputers18. Each computer is assigned a permission code that specifies which lockboxes and keys it can work with. If the computer belongs to an agency, it will be assigned a permission code of 2. A computer with a permission code of 2 can only be used to interface, through a stand, with keys and lockboxes assigned to that same agency. If the computer is owned by the board, it will be assigned a permission code of 1 and can be used to interface with all keys and lockboxes in the real estate board.
• The permission code assigned to a computer also limits the authority it can delegate to a key. A computer can delegate different levels of authority to a key by the permission codes that it loads into the key with the characterization instructions. A computer can reprogram a key's permission codes to the computer's own permission code or to any more restricted level. For example, a computer owned by an agency can reprogram a key to have permission codes of 2, 3 or 4. Such a computer cannot be used to program a key to have permission code of 1, for this would be delegating authority to the key higher than the computer'own authority. A board level computer, due to its permission code of 1, can be used to program or read any lockbox or key owned by the board.
COMMUNICATIONS
• Digital Reconstruction Modulation As noted, communication between the lockboxes, keys and stands of the present invention is effected by electromagnetically coupled coils. In the prior art, exchange of data over coupled coils was effected by modulating the data signal onto an audio frequency or radio frequency carrier. Such electromagnetic coupling has previously been poorly suited for use in such battery powered applications because the modulated carrier draws a relatively large amount of power from the battery.
• In order to minimize battery drain, the present invention employs a new modulation scheme, termed here “digital reconstruction modulation.” In this system (Fig. 19), the raw data signal which is switching, for example, between zero volts and two volts, is applied directly across a first, transmittingcoil300. Across a second, receivingcoil302 is induced an alternating series of positive and negative transient voltage spikes corresponding to the transitions in the data signal.
• These transient voltage spikes are applied to aSchmidt trigger circuit304. The Schmidt trigger circuit toggles states only when the voltage applied to its input is above a first threshold voltage or below a second threshold voltage. These threshold voltages are selected so that the positive transients exceed the first threshold voltage and so that the negative transients drop below the second threshold voltage. The positive transients thus cause the Schmidt trigger to toggle on and the negative transients thus cause the Schmidt trigger to toggle off. The output signal provided by the Schmidt trigger is thus identical to the data signal applied to the transmitting communications coil, reconstructed by virtue of the Schmidt trigger's hysterisis properties.
• Depending on the relative orientation of the two communicating coils, a low to high data signal transition applied across the first coil may cause a positive or a negative voltage transient across the second coil. Thus, the data signal recovered by the Schmidt trigger may be the inverse of the data signal applied to the first coil. This detail can be taken care of by starting the exchange of data between system units with a known data string. If the CPU in the receiving unit detects that the known data string is inverted, it can cause the output from the Schmidt trigger to be inverted again, bringing the signal back to its proper condition, for the remainder of the communications. Alternatively, the problem of data inversion can be eliminated entirely by insuring that the communicating components are always coupled in the desired orientation.
• One advantage of this digital reconstruction modulation is that the effective range over which the coupled coils can communicate is not, as in the prior art, determined by the current drawn by the transmitting coil. Instead, the strength of the received signal is dependent solely on the rise time and fall time of the input data signal and on the coefficient of coupling between the transmitting and receiving coils. The voltage induced in the receiving coil is proportional to the time rate of change of this input signal. Thus, limiting the current in the transmitting coil, for example by a current limiting circuit set to clamp the coil current at one milliampere, does not significantly reduce the communications range. Range is only limited by the switching speed of the component logic.
• A second advantage is that the data transmission rate is not limited by the frequency of a carrier signal carrying the data. Again, the only limits imposed are by the switching speeds that can be obtained in the coil circuit.
Adaptive Communications
• The maximum speed at which lockbox, key and stand components can communicate with one another varies as a function of temperature, component tolerances and component aging. In a worst case situation, one system component might be able to communicate at only one-third the speed of another component. Instead of using a communication speed that is certain to be within the capability of all system components (i.e. the lowest common denominator speed), the present invention employs an adaptive communications scheme that optimizes the communicating components.
• As noted earlier, communications between units are generally begun by the key sending an interrogation signal to wake up the lockbox. Before the lockbox responds with its response signal identifying the lockbox, reporting on battery state, etc., as discussed earlier, the two units first agree on a data transmission speed.
• To set the data transmission speed, each unit sends the other its shortest data element. In the present invention, a data0 is represented by a signal duration of a first period and adata1 is represented by a signal three times longer. To set the data transmission speed, the key thus sends to the lockbox a data0 at the key's top speed.Lockbox CPU28 measures the duration of this signal and stores this value in itsRAM memory30.Lockbox CPU28 then sends the key a data0 signal at the lockbox's top speed.Key CPU52 in turn counts the duration of this signal and stores this value in itsRAM memory56. CPUs in both units then compare the duration of the signal received with the duration of the signal they sent in order to determine which unit is operating more slowly. The CPU in the faster unit then reduces its data communications speed in order for the length of its data0 to match that of the slower unit. (The speed at which each unit transmits is set by a data word in the unit's RAM memory, which word can be altered by the CPU to effect the speed change). By this technique, the two units adapt to operate at the highest speed that both units can manage.
• After two communicating units agree on a data transmission speed, they then exchange bits of data, such as the data0 signal, alternately, approximately 20 times, in order to confirm that a reliable communications link has been established. If these twenty exchanges of data0 signals are completed without interruption, the communications link is considered to be reliable and the exchange of function authorizing data between units is begun.
BATTERY SYSTEMS
• A comprehensive battery monitoring system is employed in the present invention to prevent the lockbox and key batteries from failing and rendering the associated units inoperative. The battery monitoring systems rely on three independent criteria to determine when each battery is nearing the end of its useful life: elapsed time, usage and current drain from the backup battery. When the lockbox or key CPU detects either of the first two of these three low battery criteria, it loads a battery count number, such as 16, in its memory. (When the CPU detects the third low battery criteria, it immediately loads a battery count of zero in its memory). This battery count number is then decremented each time a lockbox or key operation is performed. The battery count represents the number of additional operations that the lockbox or key will perform before it curtails operation.
• If the lockbox battery is low, the key informs the user of this condition just before the key returns to sleep. Each time the lockbox and the key communicate, the lockbox indicates to the key the status of the lockbox battery. If any of the three low battery criteria have been met, the lockbox relays the lockbox battery count to the key, which in turn displays this number in the message portion of itsLCD display50 and makes visible the KEYSAFE BATTERY annunciator in the top portion of the LCD display. The key then beeps to call the user's attention to the display. The number displayed inLCD50 is the number of additional lockbox operations that the lockbox will allow before it curtails activities to prevent battery failure. The key maintains this LCD display for approximately two minutes before going to sleep.
• In alternative embodiments, the lockbox battery count is not displayed on the key's LCD display. Instead, the KEYSAFE BATTERY annunciator and the beeper alone are used to warn the user that the lockbox will soon curtail its operations. By not informing the user of the precise number of lockbox operations left, it is hoped that the user will replace the lockbox battery without delay.
• If the key battery is low, the user is reminded by the KEY BATTERY annunciator. Each time the key is powered on by the ON-CLEAR button,key CPU52 examines the portion ofkey RAM memory56 in which the key battery count is stored. Ifkey CPU52 finds a count, the count is decremented and the KEY BATTERY annunciator is made visible and remains visible for the duration of the key's operation.
• For expository convenience, the following discussion of the three low battery criteria focuses on the lockbox battery monitoring system. The key battery monitoring system is analogous.
First Low Battery Criterion
• The first low battery criterion is elapsed time. When a new battery is installed in the lockbox, a date counter is started that increments each day or other set period. The first low battery criterion is met when this count reaches a predetermined value, such as three years. That is, the system presumes that the lockbox battery is nearing the end of its useful life when it is three years old.
• The predetermined time period at which the battery is assumed to be nearing the end of its useful life can be chosen to correspond to the particular circumstances of the lockbox. For example, if the lockbox is used in a cold environment, such as in Alaska, its “shelf life” will be longer than if it is used in southern Florida. Similarly, the predetermined period can be chosen to correspond to the type of battery installed. If alkaline batteries are used, the predetermined period would be set to a longer period than if conventional carbon batteries are used.
• Replacement of the primary battery in the unit is detected bylockbox CPU28 which monitors the voltage of the primary battery. When this voltage is interrupted and then restored,lockbox CPU28 assumes that the battery has been replaced and resets the date counter accordingly. In an alternative embodiment,lockbox CPU28 is informed of the removal and subsequent replacement of a primary battery by a microswitch positioned in the lockbox battery compartment.
Second Low Battery Criterion
• The second low battery criterion is battery usage. When a new battery is installed in the lockbox, a battery capacity number is stored bylockbox CPU28 inRAM memory30. This number represents, very conservatively, the total estimated capacity of the battery. Each time an operation is performed, this number is decremented by a number representative of the energy actually consumed. The second low battery criterion is met when this battery capacity number reaches zero.
• The battery capacity number loaded intoRAM memory30 when the battery is replaced could again be chosen to correspond to the particular circumstances of that lockbox. For example, if the lockbox is used in a cold environment, its battery will be less able to deliver successive large current loads than if it is used in a warm climate.
• The amount by which battery capacity number is decremented is a function of the particular operations performed and their duration. In an exemplary lockbox system, the operations can be grouped into three classes: operation of a pair of locking solenoids, operation of the communications coil and operation of the remainder of the circuitry. Each of these operations is considered bylockbox CPU28 to consume energy at a fixed rate. A pair of locking solenoids may be considered to consume energy at a rate of 3 watts, the communications coil at a rate of 5 milliwatts and the remainder of the circuitry at a rate of 1 milliwatt. Each time any of these operations is performed,CPU28 operates a corresponding timer to measure its duration. The measured duration of each operation is multiplied by its assumed energy consumption rate to estimate the amount of energy actually withdrawn from the battery. These measures of energy usage are then subtracted from the battery capacity number stored inRAM memory30 to provide an indication of the battery energy remaining. As noted, the second low battery criterion is met when this battery capacity number is decremented to zero.
• In an alternative embodiment, the second low battery criterion is simply the number of operations performed by the lockbox. When a new battery is installed, a second counter, this one an operations counter, is started. This operations counter counts the number of high power operations (i.e., lockbox operations that energize solenoids, such as OPEN and SHACKLE RELEASE) performed by the lockbox. The second low battery criterion in this alternative embodiment is met when this operations counter reaches 1000. That is, the system presumes that the lockbox battery is nearing the end of its useful life after 1000 high power operations have been performed.
Third Low Battery Criterion
• Both of the above two low battery criteria assume that the battery installed is new and functioning properly. However, in the event that a used or faulty battery is installed, a third low battery criterion is considered. The third low battery criterion is current drain from the backup battery.
• Normally, no current is drawn-fromlockbox backup battery34. The backup battery only supplies current whenprimary battery32 is not able to meet all the lockbox's power requirements. When lockboxCPU28 detects that current is being drawn frombackup battery34, this third low battery criterion is met and the system presumes that the primary battery is at the end of its useful life. In this instance, unlike the preceding two, the battery count number is immediately set to zero so that any energy remaining in the primary battery can be preserved for a SHACKLE RELEASE operation.
Additional Details on Battery Systems
• As noted, once either of the first two low battery criteria has been detected, a counter is set to an arbitrary number, such as 16, and is decremented each time an additional lockbox operation takes place. This count begins at a relatively low number, such as 16, rather than at a higher number because if the number is too high, users will likely ignore it for too long.
• In alternative systems, the battery count could increase. However, it has been found that users rarely remember what the top number is, but always know what zero means.
• If the lockbox battery count reaches zero (or is set to zero by detection of current drain from the backup battery), OPEN and SBA functions are denied to everyone except keys owned by the board itself, as determined with reference to a permission code of 1 in the key. At this point, the lockbox is of little utility. Other operations are similarly prevented, such as FILE MARK, SBA and change SBA. However, the remainder of the functions, including SHACKLE RELEASE, can still be performed, thereby allowing the listing agent (or the listing agent's broker or board) to remove the lockbox and replace the batteries. In the preferred embodiment, after the lockbox battery count reaches five, the lockbox control software will only allow the listing agent (or the listing agent's broker or board) to execute the OPEN or SBA function.
• The low battery criteria and associated numerical constants discussed above are selected so that even when the battery count reaches zero, the battery still has approximately half of its capacity left. This reserve capacity insures that the high power SHACKLE RELEASE function can still be performed. The lockbox battery capacity is prevented from draining much below this point by preventing high power OPEN functions.
Backup Battery Monitoring
• In one form of the invention, the backup batteries in the lockbox and in the key are also monitored so as to determine when they are nearing the ends of their useful lives. In an exemplary embodiment, each lockbox and key includes a software timer that counts the time elapsed during which the backup battery is the sole power source for the unit, such as when the primary battery has been removed. When this timer reaches a predetermined count, an appropriate warning message is displayed in the message portion ofkey LCD display50 indicating that the appropriate backup battery should be replaced.
• In alternative embodiments, more complex backup battery monitoring schemes, such as those used with the primary batteries, can be employed.
RADIO UPDATING
• In one form of the invention, data in lockboxes and keys throughout the real estate board can be updated by radio. By this technique, both board-wise changes of data, such as changes of lockout lists and access codes, and changes targeted to specific units, such as disabling a particular key, can be implemented simply and quickly.
• For expository convenience, the following discussion focuses on radio updating of lockboxes. However, an analogous system can similarly be employed for radio updating of keys.
• In systems employing radio updating, the data to be loaded into the memories of the lockboxes is modulated onto a subcarrier transmitted with a conventional FM broadcast. The source of the data can be a conventional modem driven fromboard computer18. A receiver in each lockbox decodes this data from the modulated subcarrier and reloads its memory according to these instructions.
• In more detail, the signals broadcast by FM stereo radio stations have a bandwidth of 200 kilohertz, 100 kilohertz on each side of the carrier frequency. The FM stereo audio and stereo pilot occupy the spectrum from the carrier frequency out 53 kilohertz each side. The portion of the spectrum from 53 to 100 kilohertz on either side of the carrier is vacant and is presently being used for a variety of other subcarrier services, such as transmission of commercial free music, educational materials and stock market reports. In the present invention, the data fromboard computer18 to be sent to the individual lockboxes is modulated on a subcarrier positioned at 76 kilohertz in the FM baseband signal, approximately midway in this vacant range of frequencies. Referring toFIG. 20, the digital data from theboard computer18 is provided to asubcarrier generator200 connected to anexciter202 of theFM transmitter204. The subcarrier generator generates the 76 kilohertz subcarrier signal which is modulated with the data.
• This modulated FM signal is received by areceiver206 in each lockbox. The received FM signal is fed from an antenna208 (discussed below) to amixer210 through an RF preselector/attenuator circuit212. RF preselector/attenuator circuit212 provides some attentuation of out of band signals while amplifying the desired signals, thereby minimizing the receiver's noise figure.Mixer210 mixes the desired FM broadcast signal received byantenna208 with a local oscillator signal from alocal oscillator214. The frequency oflocal oscillator214 is selected to produce an up-converted first intermediate frequency (IF) of 384 megahertz.
• The output fromfirst mixer210, including the 384 megahertz IF, is fed to an IFsection216. IFsection216 includes afirst filter218 which passes the desired 384 megahertz signal and rejects the unwanted mixer products.Filter218 desirably comprises a surface acoustic wave filter. The output fromfilter218 is fed to asecond mixer220.Second mixer220 mixes the signal fromfilter218 with the signal from a secondlocal oscillator222. Secondlocal oscillator222 provides a 394.7 megahertz signal, thereby yielding a down-converted second receiver intermediate frequency of 10.7 megahertz. The output fromsecond mixer220 is fed to asecond filter224 which attenuates the undesired mixer products and passes the 10.7 megahertz signal toIF amplifier circuit226.Second filter224 can be a standard 10.7 megahertz ceramic filter of the type commonly used in FM receivers.
• IFamplifier226 amplifies the 10.7 megahertz signal fromfilter224 to a level suitable for detection by a phased lockloop detector circuit228.Detector228 demodulates the IF signal and provides a wideband composite audio signal to an SCAband pass filter230. SCAband pass filter230 passes the desired subcarrier channel to anSCA decoder232, while attenuating the lower frequency audio components.Decoder232 demodulates the filtered SCA channel and provides the demodulated audio to amodem circuit234 that converts the modem signals originally encoded on the subcarrier back to digital data form. The output frommodem234 is treated just as any other data input to the lockbox, as for example through the communications coil, and is used to effect the reprogramming of thelockbox RAM memory30.
• In certain embodiments,antenna208 can includelockbox shackle22 as its principal component. In such cases, shackle22 is insulated within the case to prevent it from contacting the lockbox's electrical ground and is similarly insulated outside the case, as by an insulating vinyl rain guard enclosing the shackle, to prevent it from contacting the structure to which is is fastened. Although the shackle is a small antenna, it can be resonated by preselector/attenuator circuit212 so as to operate as a low impedance resonant antenna at the frequency of interest.
• In some lockbox mounting positions, such as on a grounded water faucet, the electrical coupling between the shackle antenna and ground may be sufficient, despite any intervening insulation, to reduce the strength of the received signal to a point at which it cannot be decoded reliably. Accordingly, it is often desirable to use an antenna that does not include the shackle as a principal element. Such an antenna may take the form of a planar coil encased in plastic and mounted on an exterior surface of the lockbox. Such an antenna can also be used on or in a radio-updated key.
• In still another form of the invention,antenna208 can comprise an insulated conductor wound aboutshackle22 so as to form a helically loaded loop.
• Because the radio updating process involves alterations to the lockbox memory, it is desirable that the updating not be interrupted by requests from keys to operate the lockbox. Consequently, it is desirable that all lockbox updating be done between the hours of midnight and 6:00 a.m., a period during which the lockboxes would not normally be in use. Each lockbox can be programmed to energize its receiver circuitry for this or any other predetermined period every night to listen for updates from the board office. This window period can be a few minutes long or a few hours long. Data sent from the central board office can be directed to all the lockboxes, or can include an introductory address data string identifying a particular lockbox to which the data is targeted. In either event, the transmissions from the board office can additionally include a reference time signal so that all lockboxes are synchronized in their operations and so that they will activate their receivers at the same time every days
• By using such a radio updating approach, maintenance of lockbox and key data is greatly facilitated and system performance is thus enhanced.
SYSTEM MANAGEMENT
• Some large real estate boards have tens of thousands of lockboxes and keys in their systems, so an integrated management system is virtually essential. In one embodiment of the invention, a multiuser, multitasking system with large amounts of on-line storage is resident at the board office and serves asboard computer18. A super microcomputer such as the NCR Tower system is a suitable machine.
• As shown inFIG. 21, a computer system for a large real estate board desirably includes atrunk interface unit94 and a plurality oftelephone lines96 to allow a plurality of remote stands16b(not shown) to interface with the super microcomputer simultaneously. In the preferred embodiment, up to eight telephone lines are used.Trunk interface unit94 thus allowssuper microcomputer18 to be interrogated over telephone lines (using DTMF tones) and allows data to be exchanged between the super microcomputer and individual lockbox and key components via stands16. In such capacity, stands16 function as remote input/output ports for the board computer and the stand' microprocessors function as smart input/output controllers.
• In the preferred embodiment,trunk interface unit94 includes aninterface module99 associated with eachtelephone line96 for decrypting incoming data and for encrypting outgoing data.Modules99 also desirably include speech synthesizers so that synthesized speech corresponding to various computer data can be sent back to individual agents over the telephone lines. Aninth interface module99, which does not include a speech synthesizer, is provided intrunk interface unit94 for interfacing with alocal stand16aresident at the board office.
• Board computer system18 also desirably includes at least onephone line98 and an associateddata modem97 for interfacing tosmaller computers18 resident at individual agency offices.
• In a typical large system, severalsmaller computers18 are distributed throughout the system. Normally, such smaller computers are limited to performing certain preselected functions. For example, the software loaded into asmall computer18 at an individual agency typically enables it to update certain lockbox parameters, such as changing the lockout list and changing the daily disable times, but prevents it from changing more sensitive parameters, such as lockbox access codes. Similarly, the software loaded into thesmall computer18 at the agency typically enables it to deactivate keys, but prevents it from reinitializing keys after they are deactivated and prevents it from changing key expiration dates and expired key access codes. Such restricted functions can only be performed by the central board computer.
• The board computer is used to keep track of all data pertinent to the system. Whenever a key or a lockbox is read or programmed, the corresponding data is entered into a system database. This database includes information on all the features and parameters heretofore mentioned, for every lockbox and key in the system. The board computer can search the database for any category of information and can generate corresponding written reports on any such subject. By such reports, the board can better target its activities. For example, the board can search the database to determine which listed properties have not been shown often and then suggest to the member agencies that the advertising of these properties be increased. Similarly, the board can monitor manpower trends and suggest staffing schedules that allocate agents to the offices and at the times that the demand is greatest.
• The above described system offers many advantages to real estate boards that span large territories. For example,keys14 are usually programmed to expire occasionally and must be rejuvenated. This is desirably done by the real estate board, rather than by the individual agencies, so as to maintain centralized control over key usage. Accordingly, as noted, most small computers resident at the various agencies are not able to rejuvenate expired keys. The agents could travel to the board office periodically to have their keys rejuvenated, but in large metropolitan areas this may be burdensome. The present system allows agents to complete all such transactions with the board computer over telephone lines. To rejuvenate an expired key, for example, the agent would place the key on astand16 and would call the board computer. The key could then exchange appropriate handshaking signals with the computer and receive from the computer the key characterization instructions needed to rejuvenate the key.
• In addition to enabling the board computer to communicate with smaller agency computers,phone line98 also permits the board computer to communicate with the vendor. Updated software can be reloaded using this link. Other diagnostic routines, such as one for analyzing a diagnostic maintenance log stored in a lockbox or a key, can be executed by the vendor on individual components by using this link to couple through the board computer to the individual components at local board or agency offices.
• The board computer includes several security features. For example, all requests for service to the computer must include proper password codes before any transactions are allowed. Certain particularly sensitive transactions may require that a user call the board computer, send appropriate passwords and then hang up. The board computer then calls the user back on a predetermined telephone line. By this and other techniques, security of the system can be maintained even if the security of the password codes is breached.
• As will be recognized from the above discussion, the addition of a centralized board computer and its associated equipment greatly increases the system's utility and provides large real estate boards with a versatile, comprehensive and integrated lockbox management system.
Initialization and Deactivation of Lockboxes and Keys by the Computer
• When the lockboxes and keys of the present invention are initially shipped from the vendor, they are not assigned to one particular real estate board. That is, the board identifying data portion of each unit's RAM memory is left unprogrammed. This field is later programmed automatically when the unit is initialized by a computer.
• Both the lockboxes and the keys of the present invention include a bit, termed here the “free agent bit,” in their respective RAM memories that indicates whether the unit has been assigned to a particular board. This bit is initially set to “0” by the manufacturer, indicating that the unit is unassigned.
• When the unit is received by the purchaser, it is placed on a stand and initialized by an initialization routine run on a computer coupled to the stand. One of the first operations performed by this initialization routine is to determine the status of the unit's free agent bit. If it is found to be “0,” the routine automatically stores in the unit's RAM memory a string of data identifying the board to which the computer itself is assigned. The computer then changes the unit's free agent bit from a “0” to a “1,” thereby preventing subsequent changes of the lockbox's or key's board ownership. By this technique, every lockbox and key is assigned automatically to the board to which the programming computer is assigned.
• After the lockbox or key is assigned to the initializing board, as described above, the initialization routine incomputer18 continues by loading the unit's RAM memory with characterization instructions as specified by the programming entity, usually the real estate board.
• After a lockbox or key has been initialized, it can then only be reprogrammed by computers assigned to the same board. If it is desired to transfer a lockbox or a key to a different board, the original owner must deactivate the unit and change the unit's free agent bit back to “0.” Thereafter, the unit will again assume the board ownership of the computer that reinitializes it.
Fraud Deterrence
• The database in the board'scentral computer18 includes data identifying each lockbox and key in the system and its operational status (initialized, deactivated, etc.). This data is used by the computer to prevent keys from being fraudulently duplicated.
• As noted, each key includes identification data indicating the key's ownership by agent, agency and board.Computer18 will not load a key with a set of identification data if it determines that a key having that particular set of identification data already exists. The system thus prevents an unscrupulous user from reprogramming his or her key so as to fraudulently assume the identity of another agent in the board. The only way an unscrupulous agent could perpetrate this fraud would be to first obtain possession of the other agent's key and to deactivate it. This function, however, cannot generally be executed without knowledge of the other agent's personal code, which the unscrupulous agent should not know. Thus, it will be recognized that the database's tracking of data on each key in the system serves an important role in deterring fraud.
MECHANICAL CONSTRUCTION OF LOCKBOX
• With reference toFIG. 3,lockbox12 includesshackle22,case100 and a hingedkey compartment door24.Door24 is retained in the closed position by a cooperatingdoor latch102 and door stem104.Door stem104 is shown inFIG. 6 as including ahook portion106, abutt portion108 and a turnedcut portion110.Stem104 is spring biased away from the back ofcase100 by aspring112 compressed betweencase100 and ashoulder114 onstem104.Door stem104 is retained in the locking position by theplungers116,118 of key compartment locking solenoids36 (FIG. 2) which engagestem104 atturned cut portion110 and limit its forward travel.
• When it is desired to opendoor24, the door is pressed inwardly. This causes door stem104 to move towards the rear of the case. This freedom of movement ofstem104 is provided by the length of turnedcut portion110, which allows the stem to move inwardly while still engaged with the extended solenoid plungers.
• After door stem104 has been moved inwardly a distance, a retainingpin120 is urged against a pivotedlever122.Lever122 pivots about apivot point124 connected to the case, thereby causing the opposite end of the lever to exert a force against anactuator button126 onmicroswitch42. Whenmicroswitch42 closes, keycompartment locking solenoids36 energize, provided the appropriate authorization signals have been exchanged between the lock and key.
• When keycompartment locking solenoids36 energize, theirplungers116,118 retract. When the plungers retract, lockingstem104 is allowed to travel forwardly, no longer bound by the engagement of the plungers in the turned cut portion of the stem. Thus, when the user releases the door, it is allowed to spring open, pushed by the force ofstem spring112 and acompressed door gasket192.
• Forward travel of door stem104 when in its unlocked condition is limited by the engagement of retainingpin120 with a stoppingportion126 ofcase100. However, by the time door stem104 has moved forwardly this distance,door latch102 has unhooked fromstem104 under the influence ofdoor latch spring128, which liftslatch102 about apivot point130.Door24 is thus free to open aboutdoor hinge132, thereby allowing access to the house key or other materials stored inkey compartment20.
• Keycompartment locking solenoids36 return to their deenergized, locking states 0.25 seconds aftermicroswitch42 is reopened.Plungers116,118 are then urged against arear barrel portion134 ofstem104 if the stem is then in its unlocked position.
• Whendoor24 is closed,latch102 engages with a hook portion ofstem104 as these components are pushed inwardly. The hook portion oflatch102 has a curved upper surface so that it lowers into its latched position automatically when it meets the case. The front entrance to the bore within which these coupled elements travel has a chamferedupper portion135 to further facilitate lowering hook portion oflatch102 into its locked position. With the latch and stem so engaged,stem104 is pushed further inwardly until the spring loadedplungers116,118 of the key compartment locking solenoids are able to engage into the turned cutportion110 of the stem. At this point, the door is locked. The door is also rendered shock proof in this state by the positioning of the latched components within the constraining bore which prevents these components from becoming disengaged.
• Reviewing the key compartment access operation, it will be noted thatdoor24 is positioned on the front oflockbox12 and pivots downwardly to expose the lockbox contents. This arrangement facilitates operation of lockboxes mounted in awkward locations, such as on ground level water faucets, especially when compared to prior art systems in which the key container had to be released from the underside of the lockbox. Similarly, the present arrangement in which the key is coupled to the lockbox simply by bringing the key near the slot in the upper front portion of the lockbox provides a substantial improvement in operating flexibility over prior art systems in which the key had to be engaged with the lockbox in a precise position and then manipulated while in that position in order to operate the lockbox.
• The use of akey compartment door24 on the lockbox of the present invention also provides a variety of security enhancing features not found in prior art lockboxes. For example, the shackle release mechanism of the present invention is concealed behind the key compartment door, thereby protecting it from vandalism and providing an additional measure of security to the shackle. Similarly, batterycompartment retaining bolt180 and tamper proof screws holdinglockbox circuit board182 and the lockbox's rear cover in place are also protected from tampering by being positioned behinddoor24.
• Turning now to release of the shackle,FIGS. 2 and 7 show that shackle22 includes aloop portion140 and twoend portions142. Each end portion includes abutt portion144 and a turnedcut portion146.Shackle22 is maintained in its locked position by a lockingbar148, shown inFIGS. 4 and 5. When in the locked position, turned cutportions146 in both ends ofshackle22 are engaged bycircular notches150 in lockingbar148. Lockingbar148 is maintained in engagement with the turnedcuts146 ofshackle22 by the locking bar's own engagement on ashackle stem162. Lockingbar148 is engaged on abutt portion160 of the shackle stem by engagement between anelongated cut164 in a flat portion.158 of the bar with agroove166 in the butt portion of the stem. Shackle stem162 is spring biased towards the front of the case by aspring156 compressed betweenflat portion158 of lockingbar148 and the rear of the case. However,stem162, and consequently lockingbar148, are prevented from moving forwardly by the engagement ofplungers168,170 ofshackle locking solenoids38 with a turned cut portion172 in the stem.
• It will be recognized that the above-described shackle locking arrangement prevents any external force, regardless of how it is applied, from imparting a load to shackle lockingsolenoids38. For example, if it is attempted to pull lockedshackle22 out ofcase100, lockingbar148 will lift slightly offshackle locking stem162 and will immediately engage a casting152 (shown also in Fig. B) in the upper portion of the case. (Casting152 fills the upper portion of the case and includes twoopenings153 sized just to allow passage of theend portions142 of the shackle). Theforce pulling shackle22 fromcase100 is thus applied entirely against casting152 and does not include any component directed againstsolenoids38.
• Similarly, if it is attempted to push lockedshackle22 intocase100, a pair ofshoulders154 on the lower portion ofshackle22 are immediately forced into engagement with a pair of protrusions174 (FIG. 8) formed on the top ofcase100. (Shoulders154 andprotrusions174 are obscured inFIGS. 2 and 3 by aplastic rain guard175 formed around shackle22). Theforce pushing shackle22 intocase100 is thus applied entirely against thecase174 and again does not include any component directed againstshackle locking solenoids38.
• Even if the ends ofshackle22 are twisted, as may occur if a shackle cable (discussed below) is used, lockingsolenoids38 are still isolated from any load. Any twisting motion of the shackle ends simply causes the turned cutportions146 of the shackle to turn harmlessly in thecircular notches150 of lockingbar148.
• If release of the shackle has been authorized,lockbox CPU28 first unlocks thekey compartment door24 to allow access to theshackle locking stem162 normally concealed behind this door.Shackle locking solenoids38 are energized for eight seconds beginning two seconds afterdoor24 is opened. (as detected by microswitch42). Whenplungers168,170 of energizedshackle locking solenoids38 attempt to retract, however, they are prevented from doing so by their frictional engagement with the edge of the turned cut portion172 inshackle locking stem162. This engagement is maintained byspring156 which pushes the edge of the turned cut portion172 of the stem against the sides of the solenoid plungers.
• In order to release the shackle, the user must pressshackle locking stem162 rearwardly a short distance so as tofree plungers168,170 from their frictional engagement with the edge of turned cut portion172 of the stem. When stem162 is pressed rearwardly in this manner, energizedsolenoids38 immediately retract their plungers from the stem. When the plungers retract, stem62 is allowed to travel forwardly, no longer bound by the plunger' engagement in the turned cut portion172 of the stem. Thus, when the user releases the stem, the stem is allowed to spring forwardly, pushed by the force ofcompressed spring156.
• When shackle stem162 moves forwardly under the force ofcompressed spring156, it causes theshackle locking bar148, linked to the stem atbutt portion160, to also move forwardly. This forward movement ofshackle locking bar148 disengages the circular notches in the locking bar from the turned cutportions146 in the shackle. (Forward travel ofstem162 and lockingbar148 is limited by the locking bar's engagement with astop member159 formed in case100). In this unlocked state, the shackle can then be freely withdrawn from the lockbox.
• Ifshackle locking stem162 is not pushed inwardly within eight seconds, lockingsolenoids38 are deenergized, thereby relocking the stem, and consequently the shackle, in place.
• (It will be noted that the above described press-to-release mechanisms provided on both the key compartment door and on the shackle locking stem serve to remove all loads from the solenoids plungers when these plungers are being retracted to their unlocked states. Consequently, the solenoids employed in the present invention can be relatively small, thereby reducing both power drain and system cost.)
• When it is desired to relock the shackle, the shackle is reinserted inopenings153 in the top ofcase100 and pressed downwardly untilshoulders154 on the shackle engage theupper protrusions174. Theshackle stem162, which is protruding forwardly under the influence ofspring156, is pressed inwardly by the user, thereby causingcircular notches150 in lockingbar158 to move back into engagement with turnedcuts146 in the shackle.Stem162 can be pressed inwardly simply by closingkey compartment door24. After the shackle stem has been pressed in a distance,plungers168,170 ofshackle locking solenoids38 spring from their unlocked positions (pressing against thebarrel portion176 of stem162) back into the turned cut portion172 of the stem. This action relocks the shackle stem in its locked position and correspondingly locksshackle locking bar148 in its locking relationship withshackle22.
• In addition to the lockbox security features already described,door locking stem104 andshackle locking stem162 also serve security functions by rendering the inner workings of the lockbox inaccessible to vandalizing users. Oncedoor24 is opened, as for example by an authorized user, the two bores in which these stems travel could provide passageways to the inner workings of the lockbox. A vandalizing user who is so inclined might attempt to tamper with the internal mechanisms through these passageways. In the present invention, however, such tampering is thwarted by stems104 and162 which occlude thesepassageways80 as to block all access to the inner workings of the lockbox.
• Reviewing other mechanical components of the lockbox briefly,primary lockbox battery32 comprises five alkaline AA cells mounted next to one another in abattery pack178 mounted in the lower rear of the unit and held in place by abolt180. An0-ring seal is provided aroundbattery pack178 and around the lockbox rear cover to prevent rain and contaminants from entering the case. Thebackup battery34 is mounted on acircuit board182 in the back of the unit, which circuit board also supports thelockbox CPU28,RAM30 and related circuitry.
• Communications coil26 is mounted in the upper front of the lockbox, adjacent a receivingnest184 into which the top end ofkey14 is inserted. Coupling betweencommunications coil26 and key14 through themetal lockbox case100 is facilitated by asmall slot186 that extends throughcase100 for the length ofcoil186. This slot is filled with an insulating resin material that also pots the communications coil in place.
• Insidekey compartment door24 is astainless steel liner188 with alip portion190 that reinforces the door and helps retain the contents near the door as the door is being closed.Cellular urethane gaskets192 are positioned at the points wheredoor24 contacts the case so as to prevent rain and contaminants from entering the case. This cellular urethane material resists caking a set, thereby assuring a long life for the door seals. An injection molded plastic bumper (not shown) can be provided on the outside of the lockbox so as to protect the fixture to which the lockbox is mounted (i.e. a door) from abrasion.
• In alternative forms of the invention, shackle22 can comprise a vinyl clad steel cable terminated with appropriately machined ends, such as ends142 onshackle22, so as to permit connection of the lockbox to trees and the like. The cable can again be provided with drip caps to prevent rain from entering the lockbox.
• Having illustrated and described the principles of our invention with reference to a preferred embodiment and several variations thereof, it should be apparent to those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. For example, although the system is described with reference to a lockbox system for containing dwelling keys, it is readily adaptable to other uses, such as in industrial security systems. Similarly, although the preferred embodiment has been described as including all the claimed features, other systems could readily be designed that include only some of these features and that include other features not here discussed. Accordingly, we claim as our invention all such modifications as may come within the spirit and scope of the following claims and equivalents thereof.

Claims (2)

1-2. (canceled)

3. In an electronic key for use with an electronic lock, the key and lock being distinct from one another and movable relative thereto, the key including a microprocessor, a battery coupled to the microprocessor, a memory coupled to the microprocessor, a keypad including at least the digits 0-9, the keypad being coupled to the microprocessor, and a communications port for sending signals to the lock, an improvement comprising:

a receiver for receiving electromagnetic radio frequency signals; and

a decoder coupled to the receiver for providing data corresponding to a received radio frequency signal to the memory to change data stored therein;

wherein characteristics of the key can be programmed remotely; and

wherein the key is programmed to identify radio frequency signals carrying data intended for said key, as opposed to other signals intended for other keys.

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