WO2005124711A2

WO2005124711A2 - Safety system

Info

Publication number: WO2005124711A2
Application number: PCT/GB2005/001675
Authority: WO
Inventors: Mark Pearson; Alister Russell
Original assignee: Polygons Ltd.
Priority date: 2004-06-15
Filing date: 2005-05-04
Publication date: 2005-12-29
Also published as: WO2005124711B1; WO2005124711A3; EP1756476A2

Abstract

A safety system has a sensor for detecting an alarm signal of a smoke alarm (10) and producing an interrupt signal (16) in response to the smoke alarm output. An interrupt device (18) is controlled by the interrupt signal (16) for interrupting the operation of a domestic appliance (20). This enables a standard smoke alarm to be fitted, and the output of the smoke alarm is used to trigger an interrupt device. This may interrupt electrical power (for example to an electric cooker) or a gas supply (for example to a gas cooker).

Description

Safety System

This invention relates to safety systems, and particularly, but not exclusively, to a system for switching off domestic appliances upon detection of an impending fire, and/or for triggering multiple alarm signals in response to such detection.

Studies have shown that 69% of domestic fires originate accidentally by electrical sources, such as electric cookers and deep fat fryers. Studies have shown that over 80% of homes are now fitted with smoke detectors providing an alarm output, and it is well established that these can save lives as well as provide an early indication of a fire hazard to reduce damage to property.

There are, however, still a large number of fires producing fatalities within houses with smoke alarms fitted. A normal smoke alarm does not provide any automatic preventative action, and automatic sprinkler systems are too expensive to be used widely in a domestic environment.

There is therefore a need for a system which responds to the detection of an impending fire or a fire hazard, and which provides preventative action, but with low equipment and installation cost.

New buildings in the UK are now required to have mains powered smoke detectors, and furthermore the detection of smoke in the vicinity of one smoke alarm is required to trigger operation of all installed smoke alarms, to ensure that all occupants hear the warning. For this purpose, mains operated smoke detectors may include a communications port, and the multiple smoke detectors in a building are wired together through the wiring infrastructure of the building. It is more difficult to provide this communication between smoke alarms in an existing building.

The benefits of mains powered smoke alarms over battery operated devices are obvious. Various adapters have been developed which enable a smoke detector to be fitted between a light socket and a light bulb, so that a mains operated device can be installed without any wiring changes and without needing any socket dedicated solely to the smoke alarm. Again, there remains a difficulty in providing communication between multiple smoke detectors when installed in this way.

According to a first aspect of the invention, there is provided a safety system comprising: a sensor device adapted to detect an alarm signal of a fire detection device and produce an interrupt signal in response to the detected alarm signal, the sensor device comprising a modulator adapted to modulate a mains power supply with the interrupt signal; and an interrupt device adapted to interrupt operation of a domestic appliance in response to the interrupt signal from the sensor device, the interrupt device comprising a demodulator adapted to demodulate the interrupt signal from the mains power supply.

The fire detection device will typically be a smoke detector, although heat sensors can also be used for fire detection purposes.

The invention enables a standard smoke detector (or other fire detection device) to be fitted, and the alarm signal of the detector is used to trigger an interrupt device. This may interrupt electrical power (for example to an electric cooker) or a gas supply (for example to a gas cooker) or an oil supply (for example to an oil burning device). This enables a cooker to be switched off when a fire detection signal is generated. There is, however, no need for any wiring to be installed between the sensor device and the interrupt device because interrupt signals are modulated onto the mains electricity supply. The system can be low cost and have low (or no) installation costs.

In one example, the sensor device comprises a sound sensor adapted to detect an audible alarm signal. However, the sensor device preferably comprises an electrical sensor adapted to detect an electrical alarm signal of the fire detection device. Of course, this electrical signal may comprise either a decrease or increase in the voltage on a line, or alternatively a particular waveform.

The system may comprise a plurality of the interrupt devices so that the operation of several appliances can be controlled. The sensor device may then be adapted to produce a plurality of different interrupt signals, each for controlling different ones of the interrupt devices to interrupt operation of different domestic appliances. Alternatively, a single interrupt signal may control all of the interrupt devices together.

In addition to interrupting operation of a domestic appliance, the interrupt devices may 5 also switch on safety equipment.

The or each interrupt device may be integrated into a domestic electric power supply socket, a power supply plug of a domestic appliance or a domestic electric cooker power supply unit. Alternatively, the or each interrupt device may be provided as an 10 adaptor for connection between a domestic electric power supply socket and a power supply plug of a domestic appliance. The or each interrupt device may be for interrupting the electricity supply to an electrical appliance.

In a particularly preferred embodiment, the or each of the interrupt device is integrated 15 into a circuit breaker device. The circuit breaker device comprises a solenoid adapted to be actuated in response to interrupt signal, in addition to its conventional functionality.

The or each interrupt device may be for interrupting the gas or oil supply to a gas or oil 20 appliance. In this case, the or each interrupt device comprises a gas or liquid valve.

The system may comprise a plurality of the sensor devices. Each sensor device may further comprise a demodulator adapted to demodulate the interrupt signal from the mains power supply and provide the interrupt signal as an alarm signal to an associated 25 safety device.

This arrangement enables multiple fire detection devices to be in communication with each other (via respective sensor devices), as well as with the interrupt devices, and again without the need for additional wiring between the fire detection devices.

'30 In a preferred embodiment, each sensor device also comprises a processing means, and each interrupt device also comprises a modulator and a processing means. The modulators, the demodulators and the processing means are then adapted to perform a system configuration process. In this way, the system can be installed without the need for additional configuration equipment such as a^'personal computer.

The modulators, demodulators and the processing means may be further adapted to perform a system diagnostic process, for example to check that all components of the system are working correctly.

Each sensor device and each interrupt device may comprise at least one user operable switch adapted to control the system configuration process and/or the system diagnostic process, and at least one light indicator adapted to indicate a status of the system configuration process and or the system diagnostic process and/or integrity of the system.

Each sensor device and each interrupt device is preferably adapted to be powered by the mains power supply with which the interrupt signal is modulated. However, each sensor device and each interrupt device is also adapted to be battery powered during interruption of the mains power supply.

According to a second aspect of the invention, there is provided a sensor device comprising: a detection means adapted to detect an alarm signal of a fire detection device; a signal generation means adapted to produce an interrupt signal in response to the detected alarm signal; and a modulator adapted to modulate a mains power supply with the interrupt signal, wherein the interrupt signal is for use in interrupting operation of a domestic appliance.

This sensor device preferably has the functionality of the sensor device of the system described above.

According to a third aspect of the invention, there is provided an interrupt device comprising: a demodulator adapted to demodulate an interrupt signal from the mains power supply; and an interruption means for interrupting operation of a domestic appliance in response to the interrupt signal. This interrupt device preferably has the functionality of the interrupt device of the system described above.

The invention also provides a multifunction device that is configurable to be either the sensor device described above or the interrupt device described above. In this way, only one design of hardware is required, and the device is simply configured as a sensor device or an interrupt device during installation.

The invention also provides a fire detection device comprising the sensor device described above. Also provided are a domestic electric power supply socket, an adaptor for connection between a domestic electric power supply socket and a power supply plug of a domestic appliance, a power supply plug of a domestic appliance, a domestic electric cooker power supply unit and a circuit breaker device each comprising the interrupt device described above.

Another aspect of the invention is a safety system comprising: a plurality of safety alarm devices, and a plurality of control devices associated with respective ones of the safety alarm devices, each control device comprising: a sensing means adapted to detect an alarm signal of a respective safety alarm device; a signal generation means adapted to produce an alert signal in response the detected alarm signal; a modulator adapted to modulate a mains power supply with the alert signal; a demodulator adapted to demodulate the alert signal from the mains power supply; and a circuit means adapted to activate an alarm of the safety alarm device in response to the alert signal, wherein, in use, the alarm of each of the safety alarm devices is activated in response to an alarm signal produced at any one of the safety alarm devices.

This aspect of the invention provides communication between multiple safety alarm devices using modulation of the power supply to the devices using superposition of an alert signal. This alert signal provides a communication link between the multiple devices so that an alarm generated at one device can trigger all the others to provide an alarm output. The system requires access only to the mains power lines within a building and does not need any dedicated wiring between the safety alarm devices. As a result, the system can be installed in existing buildings using adapter type alarm devices.

Each safety alarm device may comprise a fire detection device such as a smoke alarm, but the invention may also be used with other alarm devices such as burglar alarms. The system may also have an interrupt device controlled by the alert signal for interrupting the operation of a domestic appliance.

In a system with multiple smoke alarms, each smoke alarm (or its control circuit) can be provided with a light indicator for indicating correct operation of all smoke alarms of the system. This enables easy testing of the complete installation.

Where the system includes one or more interrupt devices, these may also be provided with a light indicator for indicating correct operation of all smoke alarms of the system. For example, the interrupt device may be a circuit breaker device in the domestic fuse box, and the correct installation and operation of the smoke alarm system can be determined by examining a control box located at the location of the circuit breaker.

The invention also provides a method of controlling the power supply to a domestic appliance, the method comprising: detecting an alarm signal of a fire detection device; producing an interrupt signal in response the detected alarm signal; modulating a mains power supply with the interrupt signal; demodulating the interrupt signal from the mains power supply; and interrupting the supply of power to the domestic appliance in response to the interrupt signal.

The invention also provides a method of controlling a plurality of safety alarm devices, the method comprising: detecting an alarm signal of one of the safety alarm devices; producing an alert signal in response the detected alarm signal; modulating a mains power supply with the alert signal; demodulate the alert signal from the mains power supply; and activating an alarm of each of the other safety alarm devices in response to the alert signal. Preferred embodiments of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a first system according to the invention; Figure 2 shows a sensor device of the system shown in Figure 1 ; Figure 3 shows an interrupt device of the system shown in Figure 1 ; Figure 4 shows a circuit breaker device comprising an alternative interrupt device according to the invention; and Figure 5 shows a mains powered smoke detector comprising an alternative sensor device according to the invention.

A first aspect of the invention relates to the automatic interruption of operation of devices, which devices may be the cause of a fire, in the event of a smoke detector providing an alarm signal.

Figure 1 shows a first system embodying this aspect of the invention. The system is for use with conventional smoke detectors 10, which produce a dedicated electrical alarm signal 12, as well as an audible output, when smoke is detected.

The system comprises five sensor devices 14, only one of which is shown, each for detecting the electrical alarm signal of a respective smoke detector 10. The five smoke detectors 10 are provided in different rooms of a building, and each detector 10 has a dedicated output providing an electrical alarm signal to the respective sensor device 14. A well as being wired to the output of a smoke detector 10, each sensor device 14 is also wired to and powered by the mains electricity power supply 16.

When an electrical alarm signal from the smoke detector 10 is detected by one of the sensor devices 14, that particular sensor device 14 generates an interrupt signal. Each of the sensor devices 14 comprises a modulator, and the sensor device 14 that generated the interrupt signal modulates the interrupt signal with the mains power supply 16.

The system also comprises an interrupt device 18 integrated into the plug socket for a domestic electric cooker 20. The interrupt device 18 is wired to and powered by the mains power supply 16. The interrupt device 18 comprises a demodulator, which demodulates the interrupt signal from the mains power supply 16. The interrupt device 18 comprises interruption means for interrupting the power supply to the domestic cooker 20 in response to the demodulated interrupt signal.

Each sensor device 14 also comprises a demodulator for demodulating the interrupt signal from the mains power supply 16. Each of the four sensor devices 14 that did not detect an electrical alarm signal 12 demodulates the interrupt signal from the mains power supply 16 and provides the interrupt signal as an alarm signal to a respective smoke detector 10. In this way, as well as interrupting the operation of the domestic cooker 20, the alarms of all five of the smoke detectors 10 in the building are activated when an electrical alarm signal is detected at one of the sensor devices 14.

Each sensor device 14 described above detects the electrical alarm signal of a smoke detector 10, which alarm signal may be provided as a dedicated electrical output from the smoke detector 10. This signal may be provided as either an increase (for example from Ov to 5v) or decrease (for example from 5v to Ov) in voltage.

In the system shown in Figure 1, the sensor devices 14 and the interrupt devices 18 are wired into and powered by the mains power supply 16, and the interrupt signal is transmitted between the devices 14, 18 over the mains power supply 16. In this way the need for additional cabling between the devices 14, 18 is avoided, resulting in easier and less costly installation. The system is particularly suitable for retrofitting into existing buildings.

In the system shown in Figure 1, the interrupt signal is superposed as a modulation signal onto one of the mains power wires 16. This superposed signal will typically be a low amplitude signal at a much higher frequency than the mains frequency, and can encode information using one of a number of conventional modulation techniques.

The use of mains signals as a carrier for overmodulated data is well known and there are various commercially available systems for performing the modulation and demodulation operations. The interrupt signal modulated with the mains power supply 16 is capable of having an extremely long range, well in excess of the ranges required in a typical domestic environment. In order to ensure that the interrupt signal does not interfere with interrupt signals generated by the sensor devices of different systems installed in other buildings, the interrupt signal is uniquely coded, and the interrupt device is adapted to only respond to interrupt signals having the appropriate code.

Alternatively, commonly coded interrupt signals may be recognised in the interrupt devices of several households where the households occupy one building, for example a block of apartments. In this way, detection of fire in one apartment may result in the operation of appliances being interrupted in all apartments, should this be desirable.

As described above, the sensor devices 14 detect an alarm signal provided as an electrical output of the smoke detectors 10. In the UK, most smoke detectors satisfy British Standard BS 5446 - Part 1 the specification being sound output of minimum 85dBA at 3 metres with a frequency to be in the range of 2200/2800Hz. In other countries, other standards may apply. Thus, in alternative embodiments of the invention, the audio output of the smoke detectors 10 may be detected by the sensor devices 14, instead of the electrical output. Such an arrangement allows the sensor devices 14 to be located away from the smoke detectors 10, provided they are still within audible range.

In these alternative embodiments, if the detection of the audible alarm signal of a BS 5446 smoke detector output is prone to accidental triggering by other sound sources, it may be preferred to employ a smoke detector with a more precisely known output, which can then be detected with a reduction or elimination of accidental triggering of the interrupt device.

Figure 2 shows a sensor device 14 of the system in greater detail. The sensor device 14 comprises a detection means 30, a processing means 32, a modulator/demodulator 34, a user operable push-button switch 36, light indicators 38a, 38b, a mains input/output 40 and a fire detection device output 42. The detection means 30 comprises two electrical input terminals for receiving the electrical alarm signal 12 from the smoke detector 10. The signal 12 may be provided by the smoke detector 10 as either an increase (for example from Ov to 5v) or decrease (for example from 5v to Ov) in voltage, and the two electrical terminals are provided to receive different ones of these input types.

The alarm signal received by one of the electrical terminals of the detection means 30 is provided to the processing means 32. The processing means 32 generates a coded interrupt signal in response to the detected alarm signal. The coded interrupt signal is then provided to the modulator/demodulator 34, which modulates the coded interrupt signal with the mains power supply at the mains input/output 40.

The modulator/demodulator 34 is also operable to demodulate a coded interrupt signal generated by another sensor devices 14 from the mains power supply 16. The coded interrupt signal demodulated by the modulator/demodulator 34 is provided to the processing means 32, which provides the coded interrupt signal as an alarm signal to the fire detection device output 42. The fire detection device output 42 comprises two electrical output terminals. One of the output terminals provides an alarm signal as an increase in voltage (for example from Ov to 5v) and the other output terminal provides an alarm signal as a decrease in voltage (for example from 5v to Ov). In this way, different fire detection devices can be accommodated. The alarm signal may be used by a connected fire detection device, such as a smoke detector, to activate its internal alarm.

The sensor device 14 is powered by mains electricity, and a battery backup facility is provided. The device is protected by means of a miniature fuse link installed in series with the main live input. The battery backup facility is operable to power the device for up to 72 hours when the mains electricity supply is interrupted. In such instances, the modulator/demodulator 34 is still able to transmit a coded interrupt signal.

Figure 3 shows the interrupt device 18 of the system in greater detail. Although the system described above comprises one interrupt device 18, other embodiments of the invention may comprise several interrupt devices for respective different domestic appliances.

The interrupt device 18 comprises a processing means 32, a modulator/demodulator 34, a user operable push-button switch 36, light indicators 38a, 38b, a mains input/output 40 and an interruption means 44.

The modulated coded interrupt signal from a remotely installed sensor device 14 is received from the mains power supply 16 at mains input/output 40 and demodulated from the mains power supply by the modulator/demodulator 34. The demodulated coded interrupt signal is provided to the processing means 32. The processing means 32 receives the coded interrupt signal and, in response, provides control signals to the interruption means 44. Interruption means 44 comprises a relay 50 for interrupting operation of the domestic appliance 20.

As shown in Figure 3, the interrupt device is integrated into a plug socket. A switch 52 of the plug socket is provided in the path of the mains live wire 54, and the relay 50 is in series with the switch 52. The relay 50 is a bistable device, so that a control signal is required to open the relay 50, and a further control signal is required to reset the device and close the relay 50. The interrupt device may instead be integrated into a plug rather than into a plug socket, in a similar manner or provided in-line in a mains cable.

Like the sensor device 14, the interrupt device 18 is powered by mains electricity, and a battery backup facility is provided. The interrupt device is also protected by means of a miniature fuse link installed in series with the main live input. The battery backup facility is operable to power the device for up to 72 hours when the mains electricity supply is interrupted. In such instances, the modulator/demodulator 34 is still able to receive and demodulate a coded interrupt signal.

Each of the sensor devices 14 and the interrupt device 18 of the system has the user operable switch 36 and the light indicators 38a, 38b. Each device 14, 18 also has the processing means 32. The user operable switch 36 and the light indicators 38a, 38b of the devices 14, 18 are operable, with the processing means of the devices 14, 18, to configure the system and to provide a diagnostic function.

The configuration process configures the system. The configuration process involves communication between all of the devices of the system, including the sensor devices 14 and the interrupt devices 18. The configuration process is commenced by the user holding down the user operable switch 36 on one of the devices 14, 18 for at least 10 seconds, until the light indicator 38a starts flashing at 1Hz. This step commences a configuration mode of the system, and also configures the device as the "master" device of the system.

When the user presses the user operable switches 36 of the other devices 14, 18 of the system while in the configuration mode, these other devices send a message to the master device. The processing means 32 of the master device establishes and maintains a table containing the unique addresses of all of the devices 14, 18 from which messages have been received, and all of these devices 14, 18 are then configured within the system.

During configuration, the master device sends messages to and receives messages from each of the devices 14, 18 in the system, and the light indicator 38a of each of the devices 14, 18 changes state to confirm that the device has successfully been added to the system. The messages are sent over the mains power supply 16 using the modulator/demodulators 34 of the devices 14, 18.

The devices 14, 18 of the system are together assigned a unique domain identifier, which is determined by the master device. In use of the sensor devices, interrupt signals generated by the processing means 32 are coded with this identifier in order to prevent interference between the interrupt signals of systems in different buildings, as described above.

The configuration mode is ended by the user holding down the user operable switch 36 on the master device again for a further 10 seconds, until the light indicator 38a stops flashing. The diagnostic function is operable to confirm that all devices 14, 18 of the system are operating correctly. The diagnostic function is commenced by the user pressing the user operable switch 36 of any device 14, 18 in a configured system for one second. This step causes the processing means 32 of the device to send messages to and receive messages from the other devices 14, 18 of the system so that correct operation of all devices 14, 18 the system may be confirmed. The confirmation is provided by a change in state of the light indicator 38b of the device.

In an alternative embodiment, the diagnostic function runs continuously in the background, and the light indicators 38b of all of the devices 14, 18 of the system remain illuminated to indicate system integrity.

The user operable switch 36 of the devices is also provided to enable the system to be reset, so that operation of domestic appliances 20 may be resumed after the system has been activated by an alarm signal. Again, the reset process is controlled by the processing means 32 of the devices 14, 18.

In the above system, the sensor devices 14 are described as being distinct from the smoke detectors 10. However, in alternative embodiments, the sensor devices 14 may be provided as part of the smoke detectors 10.

The example above shows only a cooker 20. The invention may be used to control the supply of power to other electrical devices, such as an electric deep fat fryer, a fan heater, an iron, a toaster, an electrically heated blanket, or many other electrical appliances. The plug sockets for each of these electrical devices may respond to the same coded interrupt signal so that the devices are all disabled together. Alternatively, each plug socket may have a dedicated coded interrupt signal, so that the sensor device 14 can be configured to disable a desired selection of electrical appliances.

In all examples described above, the system is for interrupting power to an electric device. As mentioned above, one of the main causes of fires is electric cookers. Gas cookers are clearly also a cause of a large number of fires, and the invention can also be applied to a gas cooker. In this case, the system interrupts the gas supply, and the interrupt device 18 can then comprise a shut-off valve activated by the coded interrupt signal. The shut-off valve of the interrupt device 18 is positioned in the gas supply path to the cooker (gas cooker, hob or oven) rather than in the electrical supply path. The invention may in this way also be used to interrupt operation of a gas fire.

The system may operate with a combination of gas and electric devices. For example, a number of interrupt devices 18 are provided, some (typically only one) for gas appliances and others for electric appliances.

In the system described above, the sensor device 14 is used with an interrupt device 18 to interrupt the power (electric or gas) supply to a domestic appliance. The sensor device 14 can additionally or alternatively be used to provide control signals for activating other devices.

For example, an output signal from the sensor device 14 (whether a dedicated electrical output, an electrical output modulated with the mains power supply, an audio output, an infra red output or a radio frequency output) may be used to illuminate a display panel with a visual warning indicator. The signal may also be linked to other devices such as mobile phones, security alert call centres or directly to the emergency services. The output signal from the sensor 14 can also be used to switch on (instead of off) devices, such as extraction fans and shutters.

The examples above relate to domestic applications. There are of course numerous non-domestic applications in which the invention may be employed. In addition, the sensor device may be used in applications other than for fire detection or prevention. For example specific sounds may be detected to indicate failure of engine components or bearings in an aircraft. The sensor of the invention can detect these sounds and generate control signals for illuminating warning dials.

In another example, the interrupt device may be used to trip a ring mains circuit, so that a single interrupt device can be used to disable a number of appliances plugged in at different locations around the home. Figure 4 shows a circuit breaker device 60 comprising an alternative interrupt device 18 according to the invention. The circuit breaker device is a miniature circuit breaker (MCB). The MCB has standard mountings 68, and is mains powered by means of the consumer board.

The interrupt device 18 comprises a mains input/output. The interrupt device 18 also comprises a processing means and a modulator/demodulator, provided on a PCB 64 within the MCB housing (which is shown partially cut away at 66). The interrupt device 18 also comprises a user operable push-button switch, light indicators and an interruption means.

The circuit breaker device 60 provides the conventional function of switching based on current overload. Additionally, the interrupt device 18 of the circuit breaker device 60 provides additional functionality substantially as described above with reference to Figure 3. However, the interruption means of the interrupt device 18 shown in Figure 4 comprises a solenoid, which is operable to trip the interrupt device 18. When the interrupt device is tripped, the switch 70 is toggled, as shown by arrow 72. Thus the circuit breaker provides two separate functions.

Figure 5 shows a mains powered smoke detector 70, which includes an alternative sensor device according to the invention. The smoke detector 70 is designed as an adapter that fits between a light socket 72 on a ceiling 74 and a light bulb 76, and has an integrated alarm. Smoke alarms of this type are widely available.

Within the smoke detector 70, there is access to the electrical signal that drives the integrated alarm of the smoke detector 70, and this electrical signal is used as the basis for generating the interrupt signal. The mains power line powering the smoke detector 70 provides the communication path to the interrupt device 18, which may be at the fuse box and/or in plug sockets as described above.

The smoke detector 70 has an input that receives smoke, and a smoke detection means performs a smoke detection operation. This generates an electrical alarm output for driving the alarm in a conventional manner. In accordance with the invention, this alarm output is also provided to a processing means, which operates with a modulator/demodulator to modulate an interrupt signal with the mains power supply as described above with reference to Figure 2.

The invention has been described above with the smoke alarm signal used to interrupt a power (or gas) supply to a domestic appliance. The use of a modulated mains power supply may also be of benefit in a system having multiple smoke detectors, but without the interrupt functionality.

The system then enables the alarm signal of one smoke detector to be used to trigger the audio output of all the other smoke detectors in a building. The use of the mains system to do this can also enable a fire in one apartment of a block to be used to trigger alarm signals in all other apartments in the building. The invention enables this to be achieved with no additional wiring and therefore can be implemented with adapter type smoke alarms.

The invention has been described in detail with reference to smoke detectors. The invention is applicable to other fire detection devices, and such devices include optical as well as chemical smoke detection, but also heat sensors.

Furthermore, the mains based system described above, providing communication between alarms can also be extended to other safety devices, such as burglar alarms.

The specific implementation of the circuitry has not been described in detail. This will be routine to those skilled in the art of acoustic signal processing.

Claims

CLAIMS:

1. A safety system comprising: a sensor device adapted to detect an alarm signal of a fire detection device and produce an interrupt signal in response to the detected alarm signal, the sensor device comprising a modulator adapted to modulate a mains power supply with the interrupt signal; and an interrupt device adapted to interrupt operation of a domestic appliance in response to the interrupt signal from the sensor device, the interrupt device comprising a demodulator adapted to demodulate the interrupt signal from the mains power supply.

2. A system as claimed in claim 1 , wherein the sensor device is adapted to detect an alarm signal of a smoke detection device.

3. A system as claimed in claim 1 or 2, wherein the sensor device comprises a sound sensor adapted to detect an audible alarm signal.

4. A system as claimed in claim 1 or 2, wherein the sensor device comprises an electrical sensor adapted to detect an electrical alarm signal of the fire detection device.

5. A system as claimed in any preceding claim, comprising a plurality of the interrupt devices.

6. A system as claimed in claim 5, wherein the sensor device is adapted to produce a plurality of interrupt signals, each for controlling different ones of the interrupt devices to interrupt operation of different domestic appliances.

7. A system as claimed in any preceding claim, wherein the or each interrupt device is integrated into a domestic electric power supply socket.

8. A system as claimed in any of claims 1 to 6, wherein the or each interrupt device is provided as an adaptor for connection between a domestic electric power supply socket and a power supply plug of a domestic appliance.

9. A system as claimed in any of claims 1 to 6, wherein the or each interrupt device is integrated into a power supply plug of a domestic appliance.

10. A system as claimed in any of claims 1 to 6, wherein the or each interrupt device is integrated into a domestic electric cooker power supply unit.

1 1. A system as claimed in any preceding claim, wherein the or each interrupt device is for interrupting the electricity supply to an electrical appliance.

12. A system as claimed in any of claims 1 to 6, wherein the or each of the interrupt device is integrated into a circuit breaker device.

13. A system as claimed in claim 12, wherein the circuit breaker device comprises a solenoid adapted to be actuated in response to at least one of an excessive electrical current flow, a residual current flow and the interrupt signal.

14. A system as claimed in any of claims 1 to 10, wherein the or each interrupt device is for interrupting the gas or oil supply to a gas or oil appliance.

15. A system as claimed in claim 14, wherein the or each interrupt device comprises a gas or liquid valve.

16. A system as claimed in any preceding claim, comprising a plurality of the sensor devices.

17. A system as claimed in claim 16, wherein each sensor device further comprises a demodulator adapted to demodulate the interrupt signal from the mains power supply and provide the interrupt signal as an alarm signal to an associated safety device.

18. A system as claimed in any claim 17, wherein the or each sensor device further comprises a processing means, wherein the or each interrupt device further comprises a modulator and a processing means, and wherein the modulators, the demodulators and the processing means are adapted to perform a system configuration process.

19. A system as claimed in claim 18, wherein the modulators, demodulators and the processing means are further adapted to perform a system diagnostic process.

20. A system as claimed in claim 18 or 19, wherein each sensor device and each interrupt device comprises at least one user operable switch adapted to control the system configuration process and/or the system diagnostic process.

21. A system as claimed in any of claims 18 to 20, wherein each sensor device and each interrupt device comprises at least one light indicator adapted to indicate a status of the system configuration process and/or the system diagnostic process and/or integrity of the system.

22. A system as claimed in any preceding claim, wherein the or each sensor device and the or each interrupt device are adapted to be powered by the mains power supply with which the interrupt signal is modulated.

23. A system as claimed in claim 22, wherein the or each sensor device and the or each interrupt device are adapted to be battery powered during interruption of the mains power supply.

24. A system as claimed in any preceding claim, further comprising a plurality of fire detection devices.

25. A sensor device comprising: a detection means adapted to detect an alarm signal of a fire detection device; a signal generation means adapted to produce an interrupt signal in response to the detected alarm signal; and a modulator adapted to modulate a mains power supply with the interrupt signal, wherein the interrupt signal is for use in interrupting operation of a domestic appliance.

26. A sensor device as claimed in claim 25, wherein the detection means is adapted to detect an alarm signal of a smoke detection device.

27. A sensor device as claimed in claim 25 or 26, wherein the detection means comprises an electrical sensor adapted to detect an electrical alarm signal of the fire detection device.

28. A sensor device as claimed in any of claims 25 to 27, wherein the signal generation means is adapted to produce a plurality of interrupt signals, each for use in interrupting operation of different domestic appliances.

29. A sensor device as claimed in any of claims 25 to 28, further comprising a demodulator adapted to demodulate the interrupt signal from the mains power supply and provide the interrupt signal as an alarm signal to an associated safety device.

30. A sensor device as claimed in claim 29, further comprising a processing means, and wherein the modulator, the demodulator and the processing means are adapted to perform a system configuration process, the system configuration process comprising communicating over the mains power supply.

31. A sensor device as claimed in claim 30, wherein the modulator, demodulator and the processing means are further adapted to perform a system diagnostic process, the system diagnostic process comprising communicating over the mains power supply.

32. An interrupt device comprising: a demodulator adapted to demodulate an interrupt signal from the mains power supply; and an interruption means for interrupting operation of a domestic appliance in response to the interrupt signal.

33. An interrupt device as claimed in claim 32, for interrupting the electricity supply to an electrical appliance.

34. An interrupt device as claimed in claim 32, for interrupting the gas or oil supply to a gas or oil appliance.

35. An interrupt device as claimed in claim 34, further comprises a gas or liquid valve.

36. An interrupt device as claimed in any of claims 32 to 35, further comprising a modulator and a processing means, and wherein the modulator, the demodulator and the processing means are adapted to perform a system configuration process, the system configuration process comprising communicating over the mains power supply.

37. An interrupt device as claimed in claim 36, wherein the modulator, the demodulator and the processing mean are further adapted to perform a system diagnostic process, the system diagnostic process comprising communicating over the mains power supply.

38. A sensor device or an interrupt device as claimed in any of claims 25 to 37, further comprising at least one user operable switch adapted to control the system configuration process and/or the system diagnostic process.

39. A sensor device or an interrupt device as claimed in any of claims 25 to 38, further comprising at least one light indicator adapted to indicate a status of the system configuration process and/or the system diagnostic process and/or integrity of the system.

40. A sensor device or an interrupt device as claimed in any of claims 25 to 39, adapted to be powered by the mains power supply with which the interrupt signal is modulated.

41. A sensor device or an interrupt device as claimed in claim 40, adapted to be battery powered during interruption of the mains power supply.

42. A multifunction unit configurable to be either a sensor device of any of claims 25 to 31 or an interrupt device of any of claims 32 to 37.

43. A fire detection device comprising a sensor device of any of claims 25 to 31.

44. A domestic electric power supply socket comprising an interrupt device as claimed in any of claims 32 to 37.

45. An adaptor for connection between a domestic electric power supply socket and a power supply plug of a domestic appliance comprising an interrupt device as claimed in any of claims 32 to 37.

46. A power supply plug of a domestic appliance comprising an interrupt device as claimed in any of claims 32 to 37.

47. A domestic electric cooker power supply unit comprising an interrupt device as claimed in any of claims 32 to 37.

48. A circuit breaker device comprising an interrupt device as claimed in any of claims 32 to 37.

49. A circuit breaker device as claimed in claim 48, further comprising a solenoid adapted to be actuated in response to at least one of an excessive electrical current flow, a residual current flow and the interrupt signal.

50. A safety system comprising: a plurality of safety alarm devices, and a plurality of control devices associated with respective ones of the safety alarm devices, each control device comprising: a sensing means adapted to detect an alarm signal of a respective safety alarm device; a signal generation means adapted to produce an alert signal in response the detected alarm signal; a modulator adapted to modulate a mains power supply with the alert signal; a demodulator adapted to demodulate the alert signal from the mains power supply; and a circuit means adapted to activate an alarm of the safety alarm device in response to the alert signal, wherein, in use, the alarm of each of the safety alarm devices is activated in response to an alaπn signal produced at any one of the safety alarm devices.

51. A system as claimed in claimed in claim 50, wherein each control device is provided with a light indicator for indicating correct operation of all safety alarm devices of the system.

52. A method of controlling the power supply to a domestic appliance, the method comprising: detecting an alarm signal of a fire detection device; producing an interrupt signal in response the detected alarm signal; modulating a mains power supply with the interrupt signal; demodulating the interrupt signal from the mains power supply; and interrupting the supply of power to the domestic appliance in response to the interrupt signal.

53. A method of controlling a plurality of safety alarm devices, the method comprising: detecting an alarm signal of one of the safety alarm devices; producing an alert signal in response the detected alarm signal; modulating a mains power supply with the alert signal; demodulate the alert signal from the mains power supply; and activating an alarm of each of the other safety alarm devices in response to the alert signal.