US20020063472A1 - Keyless entry system for a vehicle - Google Patents

Abstract

A keyless entry system for a vehicle comprises a portable remote unit and a vehicle-mounted base unit supporting two-way communications. The remote unit includes a first transceiver and a control and is operative to transmit a command signal to the base unit in response to actuation of the control by a user. The base unit comprises a second transceiver and a control circuit, which controls a function in a vehicle. The base unit outputs control signals to control a vehicle function in response to receipt of commands from the remote unit. The base unit also transmits an acknowledgement signal to the remote unit responsive to the command signal.

Description

BACKGROUND OF THE INVENTION
• The present invention relates generally to keyless entry systems for vehicles and, more particularly, to a protocol for a keyless entry system to provide status information to the user.[0001]
• Keyless entry systems for vehicles allow users to lock or unlock the doors of a vehicle without a key. Keyless entry systems typically take the form of a pocket-sized fob with several push buttons that lock and unlock doors and perform other functions through encoded RF signals transmitted to a vehicle-installed receiver. Keyless entry systems are a great convenience to users. With a keyless entry system, a user, whose hands are burdened, can easily lock or unlock the doors of a vehicle. Keyless entry systems also allow a user to ensure that the doors are locked as the user walks away from the vehicle, and to escape harm by unlocking the doors quickly to gain entry into the vehicle when confronted by an assailant or otherwise threatened. Some keyless entry systems allow the user to activate an alarm and transmit a call for help. Further, keyless entry systems enable the user to locate a vehicle in a crowded parking lot by unlocking and relocking the doors, thereby causing the vehicle to sound its horn or flash its lights. Because of the many benefits, keyless entry systems have become standard equipment on many new vehicles.[0002]
• Despite their many benefits, prior art keyless entry systems suffer from a number of limitations. One limitation is the range of the transmitter, which is limited by the requirements for miniaturization of the transmitter and the low capacity of its battery. Another limitation is the manner in which the keyless entry systems signal completion of a task. Many of today's keyless entry systems rely on the vehicle's horn or lights to signal completion of a task, such as locking of the doors. In certain instances, the sounding of the vehicle's horn or flashing of the vehicle's lights may attract unwanted attention. In other cases, the keyless entry system may not provide effective feedback, or may not provide any feedback at all. For example, a user who commands the vehicle to unlock its door often does not know until reaching the vehicle whether the task has been completed. Similarly, a user may signal the vehicle to lock its doors as the user is walking away from the vehicle. If for some reason the vehicle is unable to complete the task, an inattentive user may not be aware of the problem.[0003]
BRIEF SUMMARY OF THE INVENTION
• The present invention relates to a keyless entry system for a vehicle that allows two-way communication between a vehicle-mounted base unit and a portable remote unit. The portable remote unit comprises a first transceiver and a control. The transceiver in the remote unit transmits user commands to the vehicle-mounted base unit in response to actuation of the control by the user. After sending a user command to the base unit in the vehicle, the remote unit waits for an acknowledgement signal from the base unit in the vehicle. The acknowledgement signal may, for example, indicate successful receipt by the base unit of the user command or may indicate that a function or task was successfully completed. The remote unit may further include an indicator or display that informs the user that the function or task was successfully completed. In one embodiment of the invention, the acknowledgement signal may contain status information from the vehicle's control center, which can be viewed by the user on an LCD display built into the remote unit.[0004]
• In another aspect of the invention, user commands are transmitted at two distinct power levels. The remote unit initially transmits user commands at a low power level. If an acknowledgement is timely received, the process ends. However, if the acknowledgement is not timely received, the remote unit re-transmits the user command at a higher power level. Thus, the present invention conserves power by transmitting at the lower power level the majority of the time and switching to the higher power level only in those instances when the lower power level is insufficient.[0005]
• In another aspect of the invention, the available user commands that can be acted upon by the base unit may be divided into classes, with each class including one or more user commands. The power level of the initial transmission of the user command from the remote unit to the base unit may be determined by the class to which the user command is assigned. For example, user commands may be divided into two classes, one class that represents commands initially transmitted at a low power level and one class that represents commands that are always transmitted at a higher power level. This concept of separating user commands into classes can be extended to three or more classes.[0006]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is an illustration of the keyless entry system of the present invention showing the vehicle-mounted base unit and the portable remote unit.[0007]
• FIG. 2 is a functional block diagram of the portable remote unit.[0008]
• FIG. 3 is a functional block diagram of the vehicle-mounted base unit.[0009]
• FIG. 4 is a flow chart illustrating the operation of the remote unit.[0010]
• FIG. 5 is a flow chart illustrating the operation of the base unit.[0011]
• FIG. 6 shows an alternate embodiment of a remote unit incorporated into a cellular radiotelephone.[0012]
DETAILED DESCRIPTION OF THE INVENTION
• Referring now to the drawings, FIG. 1 illustrates a remote keyless entry system, denoted generally by the[0013]numeral10. Thekeyless entry system10 comprises a portableremote unit12 and a vehicle-mountedbase unit40.Remote unit12 transmits command signals containing user commands to thebase unit40.Base unit40 translates the user commands into output control signals.Base unit40 interfaces with avehicle function50 or vehicle control center. Thevehicle function50 is responsive to the output control signals from thebase unit40 to perform a function, such as locking or unlocking the vehicle's doors, activating an alarm, or turning on/off the vehicle's lights.Base unit40 further transmits an acknowledgement signal to theremote unit12 acknowledging receipt by thebase unit40 of command signals from the remote unit. The acknowledgement signal may include status information or alert information concerning the vehicle or a vehicle function. For example, the status information may indicate that a task or function subject to a command was successfully completed. As another example, the status information may indicate a problem, such as the lights being left on or a door left unlocked, that needs the user's attention.
• FIG. 2 is a functional block diagram of a relatively simple[0014]remote unit12 according to one embodiment of the invention.Remote unit12 comprises amicroprocessor14,memory16, input/output circuits18, Bluetoothmodule20,control22, andindicator24.Microprocessor14 controls the operation of theremote unit12 according to programs stored inmemory16.Memory16 may further store data needed by themicroprocessor14 to carry out its functions.Microprocessor14 communicates via I/O circuit18 with Bluetoothmodule20,control22, andindicator24.
• Bluetooth[0015]module20 is a universal radio interface that enables portable electronic devices to connect and communicate wirelessly. Bluetoothmodule20 comprises an RF transceiver operating in the2.45 gigahertz frequency band and control processor that implements the communication protocols specified by the standard known as the Bluetooth standard. Since Bluetoothmodules20 are well known in the art and are readily commercially available, further description of the Bluetoothmodule20 is omitted herein. However, it is noted here that the Bluetooth standard supports two distinct transmit power levels, a feature which is relevant to the present invention. More detailed information concerning the Bluetooth standard is contained in “Specification of the Bluetooth System - CORE,” Version 1.0b, dated Dec. 1, 1999. A more concise description of the Bluetooth standard is contained in “Bluetooth—The Universal Radio Interface for Adhoc, Wireless Connectivity” by Jaap Haartsen, published in Ericsson Review, No. 3, 1998. Both of these references are incorporated herein by reference.
• [0016]Control22 provides means for the user to assert commands to control a function within the vehicle.Control22 may be as simple as a single push button for controlling a single function within the vehicle, such as locking or unlocking the vehicle's door. Multiple push buttons could be provided to control multiple functions.Control22 could also comprise a keypad and display that allows a user to select functions from a menu of choices displayed to the user on the display. Forms of controls other than push buttons could also be used. For example,control22 may be voice-activated or may comprise a pressure sensitive input device, such as a touch pad. Virtually any type of input device could be used as acontrol22 and, therefore, the examples given above should not be construed as limiting.
• [0017]Indicator24 may, for example, comprise a tone generator, light, or voice synthesizer that conveys status information to the user. An LCD display could also be used as anindicator24 to display status information in textual or graphic form for viewing by the user. As will be further explained below, one function of theindicator24 is to indicate to the user when a task or function that is the subject of an outstanding user command has been completed.Indicator24 could also be used to indicate other status information to the user, or to provide alerts to the user, such as when someone is tampering with the vehicle.
• FIG. 3 illustrates one exemplary embodiment of the[0018]base unit40.Base unit40 comprises amicroprocessor42,memory44, input/output circuits46, andBluetooth module48.Microprocessor42 controls the operation of thebase unit40 according to programs stored inmemory44.Memory44 may further store data needed by themicroprocessor42 to carry out its functions.Microprocessor42 also functions as a control circuit. It processes user commands received from theremote unit12 and outputs control signals via I/O circuit46 to avehicle function50 to carry out those user commands.
• [0019]Bluetooth module48 is the counterpart ofBluetooth module20 in theremote unit12.Bluetooth module48 enables thebase unit40 to communicate with theremote unit12 employing the Bluetooth interface protocol.
• FIG. 4 shows an exemplary procedure used by[0020]remote unit12. The procedure shown in FIG. 4 is triggered when a user command is input (block100). In response to the input of a command by the user, theremote unit12 selects an initial transmit power level (block102) based on the command input by the user. The user commands may be grouped into classes that determine the initial transmit power level for the commands. Information concerning available user commands and classes may be stored inmemory16. Since the Bluetooth specification employs two transmit power levels, the user commands in the exemplary embodiment are divided into two distinct power classes. Those skilled in the art will recognize that the Bluetooth specification could be modified to allow more transmit power levels, or that other communication protocols allowing a higher number of power levels could be used to practice the invention.
• After selecting the initial power level (block[0021]102), theremote unit12 transmits the user command to thebase unit40 at the selected power level (block104). Theremote unit12 then waits, usually a predetermined period of time, for an acknowledgement signal from the base unit40 (block106). If the acknowledgement signal is not received after the predetermined period of time, theremote unit12 determines whether a predetermined number of attempts, referred to as MAX COUNT, has been reached (block108). MAX COUNT can be programmed by the manufacturer, or may be selected by the user and stored inmemory16. If the number of attempts to transmit the user command is less than MAX COUNT, theremote unit12 increments the power level (block110) and repeats the transmission of the user command to the base unit (block104). Theremote unit12 will continue re-transmitting the user command (block104) until an acknowledgement is received or MAX COUNT is reached. It is to be noted that theremote unit12 increments the power level inblock110 after each transmission until the maximum power level is reached. After the maximum power level is reached, all subsequent retransmissions are at the maximum power level.
• If the[0022]remote unit12 receives an acknowledgement signal responsive to a transmitted user command, the remote unit activatesindicator24 to inform the user that the acknowledgement signal was received (block112). Such indication can be made by generating an audible tone, turning on a light, synthesizing speech, or outputting text or graphics to a display device. In the latter case, the display could further display status information contained in the acknowledgement signal.
• If MAX COUNT is reached before an acknowledgement signal is received by the[0023]remote unit12, theindicator24 may be activated to notify the user that no acknowledgement was received. The failure to receive an acknowledgement after a predetermined number of attempts to transmit a user command may indicate that the user command was not carried out and the user can then act accordingly as circumstances dictate. Alternately, theremote unit12 could terminate the procedure (block114) without activating theindicator24. In this case, the lack of an indication serves as notice to the user that the transmitted user command was not received by thebase unit40.
• FIG. 5 illustrates an exemplary procedure executed by[0024]base unit40. The procedure begins when a user command is received at the base unit40 (block200). The user command may, for example, comprise a command to lock or unlock the doors of the vehicle, activate or deactivate the vehicie's alarm, or to turn on/off the vehicle's lights. Upon receiving the user command, thebase unit40 executes the command (block202). The user command is executed by outputting a control signal to avehicle function50 or vehicle control center. Thebase unit40 may then optionally gather status information (block204). The status information may indicate successful execution of the user command or may provide general status information about the vehicle (e.g., window rolled down, lights on, door ajar, etc.). After executing the user command (block202) and gathering status information (block204), thebase unit40 transmits an acknowledgement signal back to the remote unit12 (block206). The acknowledgement signal may contain the status information gathered instep204. Depending upon the implementation, the acknowledgement signal may simply indicate receipt by thebase unit40 of the user command. In other implementations, the acknowledgement could be transmitted only when an indication is received by thebase unit40 from thevehicle function50 that the user command was successfully executed.
• FIG. 6 illustrates an alternate embodiment of the[0025]remote unit12. Theremote unit12 of FIG. 6 is similar to theremote unit12 of FIG. 2 and, therefore, similar reference numbers have been used in those Figures to indicate similar parts. Theremote unit12 of FIG. 1 includes, in addition to those elements previously described in connection with FIG. 2, acellular radio transceiver60 and anaudio section70. Thecellular radiotelephone transceiver60 comprises an RF section including areceiver62 andtransmitter64. Thecellular radiotelephone transceiver60 further includes abaseband processing circuit66 for processing signals received by and transmitted from thecellular radiotelephone transceiver60.Receiver62 performs frequency down conversion, sampling, and A-to-D conversion of received signals.Transmitter64 performs digital-to-analog conversion, modulation, and amplification of transmitted signals.Baseband processing circuit66 performs digital signal processing, such as channel coding, source coding, and encryption.
• [0026]Audio section70 comprisesaudio processing circuit72,speaker74, andmicrophone76.Audio processing circuits72 code speech signals input viamicrophone76 and decode speech signals received byreceiver62, which are then output tospeaker74.Audio processing circuit72 may also include a tone generator to generate audible tones that are output tospeaker74.
• The tone generator and[0027]speaker74 thus may perform the function of theindicator24 in the first embodiment.
• The[0028]microprocessor14, in addition to the functions previously described, implements the communication protocols used by thecellular radiotelephone transceiver60. Thecellular radiotelephone transceiver60 may use a variety of different communication protocols, including Time Division Multiple Access (TDMA) communication protocols and Code Division Multiple Access (CDMA) communication protocols. There are several standards organizations which publish communication protocols, including the Telecommunications Industry Association (TIA), the Electronics Industry Association (EIA), and the European Telecommunications Standards Institute (ETSI). Standards published by these organizations include the TIA/EIA-136, IS-54, and IS-95 standards published by the Telecommunications Industry Institute and Electronics Industry Association. The Global Standard for Mobile Communications (GSM) Standard and Wideband CDMA (W-CDMA) standards are published by the Electronic Telecommunications Standards Institute.
• The[0029]remote unit12 of FIG. 6 further includes a user interface including akeypad26 anddisplay28. Thekeypad26 allows the user to enter commands, respond to prompts, and dial digits to initiate calls. The function of thecontrol22 of the embodiment in FIG. 2 is performed by thekeypad26. Thedisplay28 allows the user to view the called number, status information, and user prompts.Display28 also allows the user to view status information and may serve the function of anindicator24.
• The embodiment of the[0030]remote unit12 combines the functions of a cellular radiotelephone and keyless entry system into a single package that is convenient for the user. Other functions could also be combined with the keyless entry function. For example, theremote unit12 could take the form of a personal digital assistant that combines a cellular radiotelephone, processing capabilities, and keyless entry functions.
• The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.[0031]

Claims (24)

What is claimed is:

1. A keyless entry system for a vehicle, comprising:

a remote unit including a first transceiver and a control, said remote unit operative to transmit a command signal containing a user command in response to actuation of said control by a user; and

a vehicle-mounted base unit comprising a second transceiver to receive said command signals from said remote unit and a control circuit to control a function in said vehicle in in response to said user command, said second transceiver further operative to transmit an acknowledgement signal to said remote unit responsive to said command signal.

2. The keyless entry system according toclaim 1 wherein said remote unit further comprises an indicator to notify said user when said acknowledgement signal is received by said remote unit.

3. The keyless entry system according toclaim 1 wherein said remote unit is further operative to re-transmit said command signal after a predetermined time period if an acknowledgement from said base unit is not received.

4. The keyless entry system according toclaim 3 wherein the re-transmitted command signal is transmitted at a higher power level than the originally-transmitted command signal.

5. A remote unit for a keyless entry system, comprising:

a control actuated by a user; and

a transceiver to communicate with a base unit mounted in a vehicle, said transceiver operative to transmit command signals to said base unit in response to actuation of said control by a user and to receive acknowledgement signals responsive to said command signals from said base unit.

6. The remote unit according toclaim 5 further comprising an indicator to notify said user when said acknowledgement signal is received by said remote unit.

7. The remote unit according toclaim 5 further operative to re-transmit said command signal after a predetermined time period if an acknowledgement from said base unit is not received.

8. The remote unit according toclaim 7 wherein the re-transmitted command signal is transmitted at a higher power level than the originally-transmitted command signal.

9. A base unit for a vehicle keyless entry system comprising:

a control circuit to control one or more vehicle functions in response to user commands received from a remote unit and to generate an acknowledgement signal responsive to said user commands; and

a transceiver operatively connected to said control circuit to communicate with said remote unit, said transceiver operative to receive user commands from said remote unit and to transmit said acknowledgement signals to said remote unit.

10. The base unit according toclaim 9 wherein said acknowledgement signal includes status information concerning a status of said vehicle.

11. A keyless entry system for a vehicle, comprising:

a remote unit including a first transceiver and a control, said remote unit operative to:

transmit a command signal containing a user command to a base unit in response to actuation of said control by a user;

re-transmit said command signal if an acknowledgement signal is not received from said base unit after a predetermined time period has elapsed; and

a vehicle-mounted base unit comprising a second transceiver to receive said command signals from said remote unit and a control circuit to control a function in said vehicle in response to said user command, said second transceiver further operative to transmit an acknowledgement signal to said remote unit responsive to said command signal.

12. The keyless entry system according toclaim 11 wherein said remote unit further comprises an indicator to notify said user when said acknowledgement signal is received by said remote unit.

13. The keyless entry system according toclaim 11 wherein first transceiver in said remote unit is operative to transmit said control signal at a first predetermined power level during a first transmission and to transmit said control signal at a second predetermined power level higher than said first predetermined power level in a subsequent transmission.

14. A remote unit for a keyless entry system, said remote unit comprising:

a control actuated by a user; and

a transceiver operatively connected to said control and operative to transmit a command signal to a base unit mounted in a vehicle in response to actuation of said control by a user and to receive an acknowledgement signal from said base unit responsive to said command signal, said transceiver further operative to retransmit said command signal a predetermined number of times until an acknowledgement signal is received.

15. The remote unit according toclaim 14 wherein first transceiver in said remote unit is operative to transmit said control signal at a first predetermined power level during a first transmission and to transmit said control signal at a second predetermined power level higher than said first predetermined power level in a subsequent transmission.

16. A method of remotely controlling a function in a vehicle, comprising:

actuating a control on a remote unit by a user;

transmitting a command signal containing a user command from said remote unit to a base unit mounted in said vehicle in response to the actuation of said control;

executing said user command in said base unit by generating a control signal to control a function in said vehicle; and

transmitting an acknowledgement signal responsive to said user command from said base unit to said base unit.

17. The method ofclaim 16 further comprising re-transmitting said command signal from said remote unit to said base unit if said acknowledgement signal is not received from said base unit within a predetermined time period.

18. The method according toclaim 17 wherein re-transmitting said command signal comprises re-transmitting said command signal at an increased power level.

19. A method for controlling a user function in a vehicle, comprising:

transmitting a command signal from a portable remote unit to a base unit mounted in said vehicle;

waiting a predetermined time period for an acknowledgement signal from said base unit; and

re-transmitting said command signal if an acknowledgement signal is not received within said predetermined time period.

20. The method according toclaim 19 wherein re-transmitting said control signal comprises re-transmitting said control signal a predetermined number of times.

21. The method according toclaim 20 wherein re-transmitting said command signal comprises re-transmitting said command signal at an increased power level.

22. A method of remotely controlling a plurality of vehicle functions, said method comprising:

grouping a plurality of user commands corresponding to said plurality of vehicle functions into two or more groups, each group having an associated initial transmit power level; and

transmitting a selected user command from a remote unit to a base unit located in said vehicle, wherein said user command is initially transmitted at one of said initial transmit power levels associated with the group corresponding to the selected user command.

23. The method according toclaim 22 further comprising re-transmitting said user command from said remote unit to said base unit if an acknowledgement signal is not received from said base unit within a predetermined time period.

24. The method according toclaim 23 further comprising increasing the transmit power level if an acknowledgement signal is not received from the base unit.

Images