GB2299886A

GB2299886A - Alarm system

Info

Publication number: GB2299886A
Application number: GB9607552A
Authority: GB
Inventors: Kieron Chapman
Original assignee: Fulleon Synchrobell Ltd
Current assignee: Eaton Electrical Products Ltd
Priority date: 1995-04-11
Filing date: 1996-04-11
Publication date: 1996-10-16
Also published as: GB9507495D0; GB9607552D0; GB2299886A8

Abstract

An alarm system is provided in which each of a plurality of sounders 7 can be independently triggered, to be individually tested, in addition to normal triggering which occurs when all sounders are to be set off. Normal triggering occurs when an input voltage supplied on a lead 3 is within an operating range. Independent triggering occurs when an activating signal is received by a sensor 11. The sensor may include a receives for radio, light, microwave, infrared or ultrasonic signals. The alarm system may be a fire alarm, security alarm or general industrial alarm.

Description

2299886 is ALARM SYSTEM The present invention relates to alarm systems, in

particular to alarm systems having sound generating units comprising a sound emitting means and associated circuitry, hereinafter called 'sounders'.

Many alarm systems, such as those employed as fire alarms, security alarms and general industrial alarms, include power supply apparatus powering several sounders simultaneously. Fire alarms, for example, frequently have central power supply apparatus connected to many sounders in different respective locations throughout a building, so that people throughout the premises can be alerted in case of a fire. In many such alarm systems, the alarm is set off by triggering the power supply apparatus into an active state in which the apparatus powers all sounders of the system so as to activate them. Normally, the power supply apparatus forms part of a control unit for the alarm systems.

In alarm systems, most especially fire alarm systems, it is of the first importance that the systems be monitored frequently, or better still continuously, to ensure that no faults have developed. In the alarm systems described above the connections between the sounders and power supply may be monitored by arranging that when the power supply apparatus is not in its active state, the power supply nevertheless transmits to the sounders a voltage which does not activate them but by means of which the connections between the power supply apparatus and the sounders can be monitored. For example, if the sounders are adapted to be activated only by an input voltage between their power inputs of a given polarity, then the power supply apparatus can supply voltage of opposite polarity to them without the sounders being activated and can use this voltage to monitor the condition of the supply lines.

6878GB:JK As well as testing the connections between the sounder units, the sounders themselves must periodically be tested. This is conventionally done by triggering the power supply apparatus into its active state so that all the sounders, or at least a group of sounders, are set off, and then inspecting the sounders individually. This method of testing the sounders suffers from the disadvantage that, when each of the sounders is being inspected, all the other sounders are operating, and thus disturbing individuals who happen to be near them.

The present invention seeks to provide an alarm system in which the sounders may be conveniently tested and yet in which unnecessary disturbance is at least partially alleviated.

Therefore, at its most general, the present invention proposes that each sounder can be triggered independently, in addition to the normal triggering which occurs when all sounders are to be set off. The independent triggering then enables each sounder to be tested individually, thereby minimising disturbance, without affecting the normal setting of all the sounders.

The means for carrying out that triggering may be integral with the circuitry for driving the sound generating means, so that it forms part of the sounder, or may be formed by one or more separate components. In either case, the resulting structure is hereinafter referred to as a sounder assembly.

Accordingly, in a first aspect, the present invention may provide a sounder assembly for an alarm system, the sounder assembly comprising sound emitting means, such as a loudspeaker, power input means for receiving an input voltage to power said sound emitting means, and auxiliary switching means, said sound emitting means being operable by selecting the value of said input voltage to be within an operating range and also being 6878GB:JK operable by operation of said auxiliary switching means.

In use as part of an alarm system, a sounder assembly according to the invention can be connected to power supply apparatus and caused to sound either by the apparatus supplying to it a voltage within the operating range (for example when the alarm is going off), or, when it is desired to test the sounder assembly, by operation of the auxiliary switching means. Since in the latter case only the sound emitting unit of a single sounder assembly will be activated, that sounder assembly can be tested individually (ie without activation of the other sounders assemblies) without being disconnected from the power supply apparatus.

Preferably the auxiliary switching means comprises sensor means operative upon receipt of a triggering signal to activate the sound emitting means. In this way, the sounder assembly can be tested by supplying to the sensor a triggering signal.

The sensor means is preferably adapted to receive signals which can be transmitted from a distance. For example the sensor means may include a receiver for radio signals, light signals, microwave or infrared signals, or even ultrasonic signals. This has the advantage that even if the sounder assembly is positioned in a relatively inaccessible location (for example a location selected to be inaccessible to vandals or burglars), it can still be tested by supplying the triggering signal to it from a distance.

Preferably the sounder assembly is arranged to receive electrical power from the power input means irrespective of whether the input voltage is in the operating range. For example, if, as described above, the auxiliary switching means comprises sensor means, the sounder assembly may be adapted to draw power continually or intermittently from the power supply means to power the 6878GB:JK sensor means.

In a second aspect the invention provides an alarm system comprising power supply apparatus for generating a supply voltage, a plurality of sounder assemblies, and electrical connection means for electrically connecting said power supply apparatus to said sounder assemblies such that the supply voltage generates an input voltage at the sounder assemblies, each said sounder assembly comprising sound emitting means, power input means for receiving the input voltage from said connection means to power said sound emitting means, and auxiliary switching means, the sound emitting means being operable by controlling the power supply apparatus such that the input voltage is within an operating range, and also being operable by operation of said auxiliary switching means.

Preferably the power supply apparatus comprises triggering means for triggering it into the state in which it supplies voltage within the operating range to each said sounder assembly.

The power supply apparatus is preferably arranged to supply a voltage outside the operating range to the sounder assemblies when the power supply apparatus is not in its active state. This voltage may for example be used to power the sound emitting means when actuated by the auxiliary switching means. In this case, the auxiliary switching circuit of each sounder assembly may be powered, if powering is necessary, from the voltage outside the operating range supplied by the power supply apparatus.

The power supply apparatus may further comprise a monitoring circuit which monitors the connection means using this voltage. The monitoring circuit may then be sensitive both to faults in the connection means and to power drawn by the sound emitting means when activated by 6878GB:JK the auxiliary switching means. Thus, the monitoring circuit can detect unauthorized operation of the auxiliary switching means.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of a sounder assembly according to the present invention; and Figure 2 shows a circuit diagram of the sounder assembly of Figure 1.

Referring firstly to Figure 1, a sounder assembly 1 receives electrical power from a power supply apparatus (not shown) through connection leads 3, 5. Electrical power is used to power sound emitting unit 7, that is to say a sounder. Operation of the sounder 7 is controlled using control circuit 9, which operates the sounder 7 in either of the two cases (i) that the input voltage supplied by lead 3 is within the operating range, or (ii) that an activating signal has been received by a sensor 11.

Although the control circuit 9 and sensor 11 are illustrated separate from the circuitry of the sounder 7, one or both of them may be totally integrated with the circuitry of the sounder 7.

Turning now to.Figure 2, a diagram is shown of a suitable circuit for use in a sounder assembly according to the invention. The control circuit 9 is powered by voltage between inputs 13, 15 which are electrically connected to respective leads 3, 5. The bridge rectifier 17 ensures that the voltage V, is greater than zero, and equal to the higher of the two inputs 13, 15.

A polarity sensor 19 is provided to determine the polarity of the voltage difference of the input 13, and this information is input to control unit 21. Control unit 21 also receives information from sensor 11 6878GB:JK 6 concerning whether the sensor 11 has received a triggering signal.

The sounder 7 includes a drive unit 23 and a loud speaker 25. In either of the cases that the polarity sensor 19 detects that the voltage input 13 is positive, or that the sensor 11 has received a triggering signal, the control unit 21 causes the driver unit 23, which draws power from the bridge 17, to power the loud speaker 25. Alternatively, the control unit 21 can control the supply of power to the driver unit 23. In this case, power is supplied to the driver unit 23 by the control circuit 21 either when the voltage input 13 is positive or when the sensor receives the triggering signal, but not at other times. This conserves power, since only the control unit 21 is thus powered continuously.

In this embodiment power from the sensor 11 is drawn from the input terminals 13, 15 via the control unit 21 and leads 25, 27. This power is drawn irrespective of the voltage of the input 13.

Although the invention has been described above with reference to a single embodiment, many variants are possible in the scope of the invention, as will be clear to one skilled in the art. For example, in alternative, embodiments, the sensor means is provided with an internal power supply, and thus does not have to rely upon power drawn from the input terminals of the sounder unit. The sounder assembly may also be provided with a memory, so that once it has been activated, either by an input voltage or by receipt of a triggering signal, it continues to sound, at least for a suitable period of time even if the input voltage moves out of the operating voltage or the triggering signal is removed.

6878GB:JK CTIAIMS 1. An alarm system comprising power supply apparatus for generating a supply voltage, a plurality of sounder assemblies, and electrical connection means for electrically connecting the power supply apparatus to the sounder assemblies such that the supply voltage generates an input at the sounder assemblies, each said sounder assembly comprising sound emitting means, power input means for receiving the input to power the sound emitting means and auxiliary switching means, the sound emitting means being operable by controlling the power supply apparatus to supply the input and also being operable by operation of the auxiliary switching means.

Claims

2. An alarm system according to Claim 1, in which the power supply

apparatus comprises triggering means for triggering it into an active state in which it supplies voltage within the operating range to each said sounder assembly.

3. An alarm system according to Claim 2, in which the power supply apparatus is arranged when not in its active state to supply a voltage outside the operating range to each said sounder assembly.

4. An alarm system according to any one of Claims 1 to 3, wherein the input is a voltage within an operating range.

5. An alarm system according to Claim 4, in which the power input means of each sounder assembly is arranged to receive electrical power from the power supply apparatus irrespective of whether the input voltage is within the operating range.

6. An alarm system according to Claim 4 or Claim 5, in which the power supply apparatus comprises a monitoring circuit which monitors the connection means and/or the sounder assemblies using the voltage supplied to the sounder assemblies when the power supply apparatus is not 6878GB:JK - 8 in its active state.

7. An alarm system according to any of the preceding claims, in which the auxiliary switching means comprises sensor means operative upon receipt of a triggering signal to activate the sound emitting means.

8. An alarm system according to Claim 7, in which the sensor means includes a receiver for a triggering signal which is an infrared, an electromagnetic or sonic signal.

9. A sounder assembly for an alarm system, the sounder assembly comprises sound emitting means, power input means for receiving an input signal to power the sound emitting means, and auxiliary switching means, the sound emitting means being operable by application of the input signal and also being operable by operation of the auxiliary switching means.

10. A sound assembly according to Claim 9, in which the auxiliary switching means comprises sensor means operative upon receipt of a triggering signal to activate the sound emitting means.

11. A sounder assembly according to Claim 10, in which the sensor' means includes a receiver for a triggering signal which is an infrared, an electromagnetic or sonic signal.

12. A sounder according to any one of Claims 9 to 11, wherein the input is a voltage within an operating range.

13. A sounder assembly according to Claim 12, which the power input means is arranged to receive electrical power irrespective of whether the input voltage is within the operating range.

14. A method of testing an alarm system comprising power supply apparatus for generating a power supply, a plurality of sounder assemblies, and electrical connection means for electrically connecting the power supply 6878GB:JK - 9 apparatus to the sounder assemblies such that the power supply voltage generates an input voltage at the sounder assemblies, each said sounder assembly comprising sound emitting means, power input means for receiving the input to power the sound emitting means and auxiliary switching means, the sound emitting means being operable by controlling the power supply apparatus to supply the input and also being operable by operation of the auxiliary switching means; the method comprising, at a time when the power supply apparatus does not supply all input, in operating the auxiliary switching means of one or more of the sounder assemblies to operate the sound emitting means of thereof. 15. A method according to Claim 14, wherein the auxiliary switching means of each sounder assembly comprises sensor means operative upon receipt of a triggering signal to activate the sound emitting means, and the step of operating the auxiliary switching means of one or more of the sounder assemblies is performed by transmitting the triggering signal to that or those assemblies.

16. A method according to Claim 15, wherein the triggering signal is an infrared, an electromagnetic or sonic signal.

17. A sounder assembly substantially as described herein with reference to the accompanying figures.

18. An alarm system substantially as described herein with reference to the accompanying figures.

19. A method of testing an alarm system substantially as described herein with reference to the accompanying figures.