USRE41871E1 - Alarm system with individual alarm indicator testing - Google Patents

Abstract

A building alarm system includes addressable notification appliances connected to a system controller, with each notification appliance having a status indicator and an alarm indicator. The status indicator, such as an LED, provides for system test modes that avoid disruption of building occupants. To test the alarm system, the system controller selects which notification appliances to operate in response to a test alarm input and communicates to each selected appliance an instruction to operate its associated status indicator without operating its associated audible or flashing visible alarm indicators. In a troubleshooting mode, the system controller polls each of the notification appliances and receives an answer in response to the poll from any of the appliances. The controller operates the LED indicators of those appliances which answer the poll. This allows a technician to locate for troubleshooting only those appliances having an nonoperating LED indicator, perhaps due to a failure to respond to its poll. According to another aspect, each addressable notification appliances includes a microprocessor and a manually-activated switch. The microprocessor is programmed to transmit a first message in response to an activation of the switch. The system controller receives the first message from the activated appliance and in response transmits a second message instructing the appliance to operate its associated alarm indicator for a test time interval.

Description

BACKGROUND OF THE INVENTION

Typical building fire alarm systems include a number of fire detectors positioned throughout a building. Signals from those detectors are monitored by a system controller which, upon sensing an alarm condition, sounds audible alarms throughout the building. Flashing light strobes may also be positioned throughout the building to provide a visual alarm indication. A number of audible alarms and strobes, generally referred to as notification appliances, are typically connected across common power lines on a notification circuit. A first polarity DC voltage may be applied across the notification circuit in a supervisory mode of operation. In the supervisory mode, rectifiers at the notification appliances are reverse biased so that the alarms are not energized, but current flows through the power lines of the notification circuit to an end of line resistor and back so that the condition of those lines can be monitored. With an alarm condition, the polarity of the voltage applied across the power lines is reversed to energize all notification appliances on the notification circuit.

An alternate method of supervising audible alarms and strobes is to use addressable appliances as disclosed in U.S. Pat. Nos. 4,796,025 (Farley et al.); 5,155,468 (Stanley et al.); and 5,173,683 (Brighenti et al.). Each addressable appliance bas an individual address and is polled by the system controller to determine if it is present. When an appliance receives its associated address, its response to the poll indicates that the communication path between the appliance and the system controller is operational.

During installation of a building fire alarm system, the system controller is programmed to associate each fire detector input signal with one or more notification appliance circuits (in the case of non-addressable appliances) or individual notification appliances (in the case of addressable notification appliances). In a conventional system installation, programming can be verified by initiating an alarm input (e.g., smoke detector, pull station) to cause an alarm notification through the associated audible and visible notification appliances. A technician can then verify the programming by walking through the building and checking that the appropriate audible and visible notification appliances have been operated. Once the conventional building fire alarm system becomes operational, testing of individual notification appliances is accomplished by causing all of the appliances on a notification circuit to operate, followed again by a technician walking through the building to check that all of the appliances are functioning.

SUMMARY OF THE INVENTION

The conventional methods of verifying system installation and troubleshooting notification appliances can be very disruptive, especially in buildings such as hospitals which do not typically have an unoccupied period during which testing can be performed.

In accordance with the present invention, notification appliances connected to a system controller are provided, with each appliance having an alarm indicator such as an audible alarm or strobe, and a status indicator, such as an LED. The status indicator provides for system test modes that are not disruptive to building occupants. Accordingly, to test the programming of an alarm system, the system controller selects which notification appliances to operate in response to a test alarm input which is specific to one or more alarm condition detectors and communicates to each selected appliance an instruction to operate its associated status indicator without operating its associated alarm indicator. A technician can then check that the correct appliances have been operated, thus verifying the programming without disturbing the occupants of the building by activating the appliance. For notification appliances having both an audible alarm and a strobe, the status indicator can be operated at different rates to distinguish whether the audible alarm, strobe, or both would normally have been energized.

In a troubleshooting mode where there has been a supervision failure, the system controller selects to operate the status indicator of those notification appliances which respond to polling. This allows a technician to locate for troubleshooting purposes only those appliances having a nonoperating status indicator.

According to another aspect of the invention, an alarm system includes plural notification appliances that each have an alarm indicator, a microprocessor and a locally-activated switch. The microprocessor is programmed to transmit a first message in response to a manual activation of the switch. A system controller connected to the notification appliances receives the first message from the activated appliance and in response transmits a second message instructing the appliance to operate its associated alarm indicator for a test time interval. In a preferred embodiment, the locally-activated switch is a magnetic-field sensitive switch. In an alternate embodiment, the switch comprises an infrared sensor and switch circuitry. Each notification appliance further includes a status indicator which the microprocessor is programmed to operate in response to the switch activation for a second test time interval.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views.

FIG. 1 illustrates an alarm system embodying the present invention.

FIG. 2 is an electrical schematic block diagram of an audible/visible alarm notification appliance in the system of FIG.1.

FIG. 2A is a schematic block diagram of an alternate embodiment of an audible indicator circuit for the appliance of FIG.2.

FIG. 3 is a flowchart illustrating an installation verification process of the present invention.

FIG. 4 is a flowchart illustrating a troubleshooting process of the present invention.

FIG. 5 is a flowchart illustrating an individual appliance testing process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A system embodying the present invention is illustrated in FIG.1. As in a conventional alarm system, the system includes one ormore detector networks12 having individual alarm condition detectors D which are monitored by asystem controller14. When an alarm condition is sensed, the system controller signals the alarm to the appropriate devices through at least onenetwork16 of addressable alarm notification appliances A. Because the individual devices are addressable, supervision occurs by polling each device so that anetwork16, also referred to as a notification appliance circuit (NAC), can include one or more single-ended stub circuits22. As shown, all of the notification appliances are coupled across a pair ofpower lines18 and20 that also carry communications.

A preferred combination audible/visible notification appliance24 is presented in FIG.2. Embodiments of individual audible and visible appliances are subsets of this schematic.Lines18,20 are coupled across over-voltageprotector110 to protect theappliance24 against power surges and lightning strikes. Amicroprocessor126 controls and operatesaudible indicator circuit106, flashingvisible indicator circuit108 andstatus indicator120. Ashift register118 provides themicroprocessor126 with serial access to six address bits set inDIP switch112, three device code bits set inregister116, and a switch status bit set byswitch114. Data-in and sync state inputs are provided to themicroprocessor126 through sync/data detector122. Themicroprocessor126 includesdata output line138, strobe powerconverter control line140,strobe flash trigger142,horn control line144, andLED control line146. Themicroprocessor126 also includes random access memory (RAM)129 and read only memory (ROM)127. In an alternate embodiment, the functions ofmicroprocessor126, as disclosed hereinbelow are performed by an application specific integrated circuit (ASIC).

Theaudible indicator circuit106 includes adrive circuit134 that drives anaudio transducer136. In the embodiment ofFIG. 2, the audio transducer is a conventional piezo element. Themicroprocessor126 operates theaudible indicator circuit106 by sweeping thedrive circuit134 with a nominal 3 kHz square wave signal onhorn control line144. In an alternate embodiment (FIG.2A), theaudible indicator circuit106 can instead include aspeaker136′ as the audio transducer through which themicroprocessor126 plays prerecorded announcements retrieved fromROM127. In the alternate embodiment ofappliance24, anaudible indicator circuit106′ includes aselector137 which selects between the 3 kHz square wave signal online144 and anaudio signal135 under control of themicroprocessor126 oncontrol line143. Theaudio signal135 is provided to theappliance24 from thesystem controller14 either on a separate loop or superimposed on power/communication lines18,20.

The flashingvisible indicator circuit108 can be easily constructed from the teachings in U.S. Pat. No. 5,559,492 (Stewart et al.), which is incorporated herein by reference in its entirety. Thevisible indicator circuit108 includes aboost converter128,capacitor131, high-voltage trigger130 andflash bulb132. Theboost converter128 is a charging circuit powered by thepower lines18,20 that applies a series of current pulses tocapacitor131 online133 to charge the capacitor. The high-voltage trigger130 is a firing circuit that causes thecapacitor131 to discharge through theflash bulb132. To avoid overcharging of thecapacitor131 as the flash bulb waits for a firing signal, themicroprocessor126 disables theboost converter128 throughcontrol line140 when the capacitor reaches a firing voltage level. In the alarm system disclosed in Stewart et al., the firing circuit responds to a change in voltage across the power lines to trigger the discharge. In the preferred embodiment of thenotification appliance24 of the present invention, the microprocessor triggers discharge through strobeflash trigger line142.

Thestatus indicator120 in the preferred embodiment is an LED that is controlled by themicroprocessor126 throughcontrol line146. While an unobtrusive LED indicator is preferred, it should be understood that in other embodiments the status indicator can include audible indicators such as a horn or speaker or even thecircuit106 operated at a much lower volume.

Theswitch114 is a manually-activated switch, which is preferably a magnetic-field sensitive switch such as a reed switch. In a typical application, a technician manually passes a magnet across the face of the appliance to activate the reed switch. A single appliance test process using the switch is described further herein.

In an alternate embodiment, theswitch114 comprises an infrared receiver responsive to an activation signal from an infrared transmitter operated by the technician. A detected activation signal sets the switch status bit inshift register118.

Thenotification appliances24 are operated through commands received over theNAC16 from thesystem controller14. At system installation and at predetermined intervals, the appliances monitor theNAC16 for a timing-training message broadcast from thesystem controller14 which causes each appliance to adjust its local timebase to match that of thesystem controller14.

The alarm system has two normal modes of operation: SUPERVISORY mode and ALARM mode. In the SUPERVISORY mode, thesystem controller14 applies 8 to 9 VDC to theNAC16 to provide only enough power to support two-way communications between the system controller and themicroprocessor126 of eachappliance24. In the ALARM mode, thesystem controller14 applies a nominal 24 VDC to theNAC16 to supply power to operate the audible and visible indicator circuits of the appliances.

In the preferred embodiment, thesystem controller14 communicates digital data to the appliances using a three level voltage signal: sync (less than 3 volts), data1 (8-9 volts) and data0 (24 volts). Communication from thenotification appliance24 towards thesystem controller14 is effected by themicroprocessor126 ondata line138.

When not performing any functions, the microprocessor is put into a sleep mode to conserve power. The sync level signal is used to wake up themicroprocessor126 from a low power state. The appliance then checks whether a message is addressed to it and, if so, acts on the message. After a predetermined period with no activity, the device goes back to sleep. On reset or power up, themicroprocessor126 reads theDIP switch112 to obtain the individual appliance address. It then monitors theNAC16 for polls to this address by thesystem controller14. Device code bits hardcoded intoregister116 indicate the appliance type, e.g., horn, flashing bulb or both.

An appliance can only act on a command by the system controller to turn on when the appliance is in ALARM MODE. Anappliance24 does not go into ALARM MODE operation until the voltage across theNAC16 exceeds the minimum ALARM MODE voltage (e.g., 24 VDC) for more than 5 milliseconds, as determined by themicroprocessor126. Theappliance24 turns off when the line voltage is determined to have dropped below the minimum ALARM MODE voltage continuously for greater than 5 milliseconds.

Selected groups ofappliances24 can be controlled by using group designators programmed by thesystem controller14. Theappliance24 retains the group designators inRAM129 of themicroprocessor126. In addition, default group designators include groups designated all audibles, all visibles, and all appliances.

Operation of thenotification appliance24 in accordance with the present invention will now be described with reference toFIGS. 3-5.

A flowchart illustrating an installation verification process of the present invention is shown in FIG.3. Thenotification appliances24 are installed and the system controller is programmed during a system installation atstep100. To test and verify the programming of the controller, a system test mode is entered at thesystem controller14 atstep102 and a technician testing the system initiates an alarm input at a particular alarm condition detector (e.g., smoke detector, pull station) atstep104. Atstep106, the alarm input is detected and the system controller selects one or more notification appliances to be operated that correspond to the specific detected alarm input atstep108. In response, the system controller transmits an LED ON message to the selected notification appliances atstep110 to operatestatus indicator120. This then allows the technician to conduct a “silent test” of the appliances without actually sounding the audible indicators or flashing the visible indicators. After a test time interval, or on a command by the technician, the system controller transmits an LED OFF message to the selected appliances atstep112 to deactivatestatus indicator120 and the alarm system returns to normal operation atstep114.

In the case of a combination audible/visible notification appliance, there are alarm modes in which the flashing visible indicator, audible indicator or both are to be operated. Therefore, it is important when conducting silent testing of the appliances to provide an indication to distinguish such alarm modes. One method is to operate thestatus indicator120 at a first rate to indicate that both the audible and visible indicators are being tested, at a second rate to indicate only the visible indicator, and at a third rate to indicate only the audible indicator. The different rates can instead be different on/off duty cycles.

FIG. 4 is a flowchart illustrating a troubleshooting process of the present invention. In the normal mode of operation, thesystem controller14 supervises thenotification appliance circuit16 by polling thenotification appliances24 atstep200. The appliances respond to the poll with an answer message transmitted back to the system controller atstep202. If all of the appliances answer the poll atstep204, then the system controller can assume that the appliances are functional and that the wiring has integrity. If an appliance does not answer the poll, a system trouble is issued by the system controller atstep206. Atstep208, if the technician selects a diagnostic command, the system controller enters a troubleshooting mode on thespecific NAC16 associated with thatparticular appliance al210. The system controller atstep212 transmits an LED ON message to the ALL APPLIANCES group address on the specifiedNAC16. All of the appliances then operate their respective LED indicators, except for the faulty appliance, which can be visually identified by the technician. After a test interval long enough to allow proper identification of the faulty appliance or on a command by the technician, the system controller transmits an LED OFF message to the ALL APPLIANCES group address and the system returns to normal alarm operation atstep214.

As noted in the background, conventional testing of a single notification appliance is accomplished by causing all of the appliances on a notification circuit to operate, followed by a technician walking through the building to check that all of the appliances are functioning. This process can be very disruptive in buildings such as hospitals which do not typically have an unoccupied period for such testing. A flowchart illustrating an individual appliance testing process in accordance with the present invention is shown in FIG.5. Atstep300, thesystem controller14 sends a broadcast message to the appliances to put them into a manual test mode. In this manual test mode, the status ofmagnetic switch114 is monitored by themicroprocessor126 atsteps302,304,306,308. At step302 a timer is reset and the status of the magnetic switch bit is checked. If a switch activation has occurred, then atstep306 the timer is incremented and atstep308 the timer value is compared with a sample period. If the timer value is less than the sample period, the status checking loops throughsteps304,306,308 until either a switch activation is not detected atstep304 or the timer value reaches the sample period atstep308. In an alternate embodiment, the status checking loop304-308 can be modified to only require the switch to be activated for a portion (e.g., 90%) of the sample period to account for “bounce” in the switch.

After the timer value reaches the sample period, meaning that the switch has been activated for the duration of the sample period and therefore a legitimate switch activation has occurred, themicroprocessor126 atstep310 operates thestatus indicator120 briefly (e.g., 500 milliseconds) to serve as a local acknowledgment to the technician. The microprocessor then sends a SWITCH ACTIVE message to the system controller. The system controller receives the SWITCH ACTIVE message and may note the event in a system history log before putting thenotification appliance circuit16 into ALARM MODE and sending an APPLIANCE ON message to the particular activated appliance atstep312. Themicroprocessor126 receives the APPLIANCE ON message and operates the appropriatealarm indicator circuits106,108. After a test interval, the system controller sends an APPLIANCE OFF message to turn off the alarm indicator circuits.

In an alternate embodiment, the individual appliance testing process is modified to aid the technician in determining which appliances have been tested and which are yet to be tested. Accordingly, at the commencement of manual test mode, thesystem controller14 sends a broadcast LED ON-PERIOD message to cause the appliances to operate thestatus indicator120 at a specified periodic rate.

Upon a switch activation as described above with respect tosteps304,306,308 ofFIG. 5, the operation of the individual status indicator atstep310 is modified to instead deactivate the status indicator, followed by the remainingsteps312 and314. In this manner, a technician is able to distinguish untested appliances (blinking status indicator) from tested appliances (extinguished status indicator). Alternatively, the testing could begin with the status indicator off and each would be turned-on to indicate testing.

Equivalents

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various is changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims.

Claims (32)

1. A method of testing a building alarm system, the method comprising the steps of:

(a) providing plural notification appliances connected to a system controller, each notification appliance having a test status indicator for indicating notification appliance test status and an alarm indicator for indicating an alarm condition to building occupants;

(b) selecting at the system controller one or more notification appliances to operate; and

(c) communicating from the system controller to each selected notification appliance an instruction to operate its associated test status indicator for verification without operating its associated alarm indicator so as to avoid disrupting the building occupants.

2. The method ofclaim 1 further comprising the step of providing a test alarm input to the system controller which is specific to one or more alarm condition detectors, and wherein step (b) comprises selecting which notification appliances to operate in response to the specific test alarm input.

3. The method ofclaim 1 further comprising, prior to steps (b) and (c), the steps of polling each of the notification appliances from the system controller and receiving an answer at the system controller in response to the polling step from any of the notification appliances, and wherein step (b) comprises selecting those notification appliances which answer the poll.

4. The method ofclaim 1 wherein step (c) comprises communicating the instruction to a group of addressable notification appliances using a group address.

5. An alarm system comprising:

plural notification appliances, each notification appliance having a test status indicator for indicating notification appliance test status and an alarm indicator for indicating an alarm condition to building occupants; and

a system controller connected to the plural notification appliances, the system controller in a test mode selecting one or more notification appliances to operate and communicating to each selected notification appliance an instruction to operate its associated test status indicator for verification without operating its associated alarm indicator.

6. The system ofclaim 5 wherein the notification appliances are addressable and the system controller communicates the instruction to a group of addressable notification appliances using a group address.

7. The system ofclaim 5 wherein the system controller selects which notification appliances to operate in response to a test alarm input which is specific to one or more alarm condition detectors.

8. The system ofclaim 7 wherein the alarm indicator comprises an audible indicator and a flashing visible indicator and wherein the test status indicator of a selected notification appliance is operated in response to the test alarm input at different rates to indicate whether the audible indicator only, the flashing visible indicator only, or both audible and flashing visible indicators are intended to be operated.

9. The system ofclaim 5 wherein the system controller is operable to poll each of the notification appliances, each notification appliance is operable to send an answer to the system controller in response to the poll, and the system controller selects those notification appliances which answer the poll.

10. The system ofclaim 5 wherein the test status indicator comprises an LED indicator.

11. The system ofclaim 10 wherein the alarm indicator comprises an audible indicator.

12. The system ofclaim 10 wherein the alarm indicator comprises a flashing visible indicator.

13. The system ofclaim 10 wherein the alarm indicator comprises an audible indicator and a flashing visible indicator.

14. A method comprising the steps of:

providing plural notification appliances connected to a system controller, each notification appliance having an alarm indicator and a locally-activated test switch;

activating the locally-activated test switch of one of the plural notification appliances;

transmitting a first message from the one activated appliance in response to the test switch activation; and

receiving the first message at the system controller and transmitting to the activated appliance a second message instructing the activated appliance to operate its associated alarm indicator for a test time interval.

15. The method ofclaim 14 wherein each notification appliance further includes a test status indicator and further including the step of operating the test status indicator of the activated appliance in response to the switch activation for a second test time interval.

16. The method ofclaim 14 wherein each notification appliance further includes a test status indicator and further including the steps of operating the test status indicators at a periodic rate and extinguishing the test status indicator of the activated appliance in response to the switch activation.

17. An alarm system, comprising:

plural notification appliances, each notification appliance having an alarm indicator and a locally-activated test switch, the appliance being programmed to transmit a first message in response to an activation of the test switch; and

a system controller connected to the plural notification appliances, the system controller receiving the first message from the activated appliance and in response to the first message transmitting to the activated appliance a second message instructing the activated appliance to operate its associated alarm indicator for a test time interval.

18. The system ofclaim 17 wherein the locally-activated test switch is a magnetic-field sensitive switch.

19. The system ofclaim 17 wherein the locally-activated test switch includes an infrared sensitive switch.

20. The system ofclaim 17 wherein each notification appliance further includes a test status indicator and wherein the activated appliance is programmed to operate the test status indicator in response to the test switch activation for a second test time interval.

21. The system ofclaim 20 wherein the second message includes an instruction to operate the test status indicator of the activated appliance for a third test time interval.

22. The system ofclaim 20 wherein the test status indicator comprises an LED indicator.

23. The system ofclaim 17 wherein each notification appliance further includes a test status indicator and wherein the appliances are programmed to operate the test status indicator at a periodic rate and the activated appliance is further programmed to extinguish the test status indicator in response to the test switch activation.

24. The system ofclaim 17 wherein the alarm indicator comprises an audible indicator.

25. The system ofclaim 17 wherein the alarm indicator comprises a flashing visible indicator.

26. The system ofclaim 17 wherein the alarm indicator comprises an audible indicator and a flashing visible indicator.

27. The alarm system ofclaim 5, at least one notification appliance comprising:

a selector which selects between a generated tone signal and an audio signal, the audio signal being provided to the notification appliance from a system controller; and

an audio transducer for broadcasting the selected signal.

28. The alarm system ofclaim 27, the audio signal being provided from the system controller by being superimposed on power/communication lines.

29. The alarm system ofclaim 27, wherein the notification appliance plays prerecorded announcements.

30. The method ofclaim 14, further comprising:

providing an audio signal from the system controller; and

in at least one notification appliance,

selecting between a generated tone signal and the audio signal, and

broadcasting the selected signal.

31. The method ofclaim 30, the audio signal being superimposed on power/communication lines.

32. The method ofclaim 30, further comprising playing, in said notification appliance, prerecorded announcements.

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