GB2281139A - Gas detector and alarm - Google Patents

Abstract

A detector 16 is provided in a housing 1. An associated male connector 2 is provided in the housing for mounting the housing to an independent cooperating female connector, for example a ceiling rose 4. In use the male connector receives electrical power from and the housing is demountably supported by the female connector. A detector and alarm circuit 16 is connected to receive electrical power from the male connector. An associated female connector 10 is also provided in the housing and is connected to receive electrical power from the male connector 2. The female connector is adapted for supporting and supplying electrical power to a cooperating device such as a ceiling light fitting 12 mountable to the associated female connector. The detector and alarm circuit includes a detector (24, Fig. 2) for detecting for example a hazardous gas condition such as smoke and a loudspeaker (25) and lamp (26) which are activated when such a condition is detected. The circuit is arranged to transmit/receive signals via the power supply. <IMAGE>

Description

A DETECTOR The present invention relates to a detector and in particular, but not exclusively, to a demountable mains operated gas detector and alarm.

Detectors such as gas alarms, particularly smoke detectors, are well known and widely used in both industrial and domestic settings. A large number of battery powered smoke detectors are installed in houses and provide a cheap way of alerting the occupants of the house to a smoke hazard. A problem with battery powered smoke detectors is that the battery can go flat thus rendering the detector inoperative. Also, it is not unknown for owners to remove the battery for another purpose thereby making the smoke detector useless.

Mains powered smoke detectors are also available and tend to be used in offices and hotels, for example. Whilst mains powered detectors do not suffer from the aforementioned disadvantages associated with the battery powered device, they nevertheless have their own problems. Unless the power supply for the detector is installed at the time the building is constructed there will be considerable expense in laying down mains cables at a later time to accommodate mains powered detectors. In addition, detectors used in an hotel or an office environment are usually connected to a central controller and further expense will be incurred by the need to provide communicating cables between each detector and the central controller.

The present invention aims to overcome at least some of the aforementioned problems.

According to the invention there is provided a detector comprising: a housing; an associated male connector in said housing for mounting the alarm to an independent cooperating female connector such that in use the male connector receives electrical power from and the detector is demountably supported by the female connector; an electrical detection circuit connected to receive electrical power from the male connector; and an associated female connector in said housing connected to receive electrical power from the male connector and adapted for supporting and supplying electrical power to a cooperating device mountable thereto.

In a preferred embodiment of the invention to be described in greater detail hereinafter, the independent cooperating female connector comprises a ceiling rose socket and the cooperating device comprises a ceiling lamp, the alarm housing being of a suitable form to fit between the ceiling rose and the cooperating device.

The above and further features and advantages of the invention are set forth with particularity in the appended claims and will become clearer from consideration of the following description of a preferred embodiment of the invention given with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a gas alarm fitted between a ceiling rose and a ceiling light fitting; and Figure 2 is a schematic circuit diagram of the gas alarm circuit.

Turning now to Figure 1 of the accompanying drawings there is shown a smoke detector in a housing 1 having an associated male connector 2 adapted to be received by cooperating female connector 3 in a ceiling rose 4. In use, the ceiling rose 4 provides support to the smoke detector by way of the cooperating female connector 3 and the associated male connector 2. The ceiling rose 4 is secured to a ceiling 5 and receives electrical power from an existing lighting wiring circuit 6. The lighting wiring circuit comprises four connections, namely: live L, neutral N, earth E, and a switched live SW.

Together the live L, neutral N and earth E lines comprise a conventional lighting ring, and the switched live SW is a line supplied in a conventional manner from a wall switch 7 (see Figure 2). The mains supply lines are connected to respective terminals of a terminal block 8, which terminals are themselves connected via lines to the female connector 3 in the ceiling rose 4.

The smoke detector 1 further comprises an associated female connector 10 which is adapted to receive a cooperating male connector 11 of a cooperating device 12. In use, the smoke detector 1 provides support to the cooperating device 12 by way of the associated female connector 10 and the cooperating male connector 11. The associated female connector 12 is electrically connected to the associated male connector 2 via lines 13, 14 which together provide the live L, neutral N, earth E, and switched live SW to the associated female connector 10. Similarly, lines 15 provide power to a detector and alarm circuit 16 which will be described in greater detail hereinafter with reference to Figure 2 of the accompanying drawings.

As shown in Figure 1 the cooperating device comprises a ceiling light fitting with electrical power being supplied from the male connector 11 to a pendant lamp holder 17 via a cable 18. It will be appreciated by those possessed of the appropriate skills that in the case of a light fitting only the switched live SW, neutral N and earth E lines need be supplied to the pendant lamp holder, and that accordingly only three of the four available connections from the male connector 11 are utilised in this example. The invention is not limited to light fittings and thus connections from the male connector 11 may be utilised as appropriate to supply the necessary power (live L, neutral N, earth E and switched live SW as appropriate) to the cooperating device.

It should be noted that as shown in Figure 1 the ceiling rose 4, the smoke detector 1 and the cooperating device 12 are formed mechanically such that in the unlikely event of a failure of the smoke detector 1 the same could be removed for repair and the cooperating device 12 be plugged directly in to the ceiling rose 4. This three-part arrangement makes installation, maintenance and replacement of the smoke detector very easy. In an office or hotel the ceiling rose 4 could be fitted at every ceiling location where a light fitting is required and a smoke detector 1 could be fitted discretely at selected locations. The ceiling rose provides a permanent mains supply by way of the lighting ring 6 thereby avoiding the need to rely on batteries to power the smoke detector 1.

Nevertheless, as a safety precaution in the event of a mains power failure, the smoke detector can be provided with a backup battery 23 at a convenient location within the housing 1.

Turning now to Figure 2, the detector and alarm circuit 16 comprises a transformer 20 which receives electrical power from the permanent live L and neutral N lines of the mains supply 6 via the connector 8.

The output from the transformer 20 is supplied to a rectifier and smoothing circuit 21 which outputs a DC supply to a control processor 22 and to a charging circuit including the backup battery 23. The control processor 22 is connected to a conventional gas detector 24 and together the detector 24 and control processor 22 detect gas, for example-smoke, using any of the many well known methods. The circuit 16 further comprises an audible output, i.e. a loudspeaker 25, and a visual output, i.e. a lamp 26.

In response to the detector 24 detecting a hazardous gas condition, for example smoke, the control processor is arranged to activate the loudspeaker 25 and the light 26. The circuit is provided with a test button 27 and the control processor 22 is configured to respond to activation of the test button 27 by entering a self-test routine and activating the loudspeaker 25 and/or the light 26 in the event that the circuit is found to be operating correctly.

In addition to these conventional smoke detector features, the circuit 16 is provided with the following additional features. A relay 28 provided in the line 14 between' the connector 8 and the connector 10 is actuated by the control processor in the event of the detection of a hazardous gas condition. The relay 28 comprises a normally closed connection and on actuation of the relay 28 by the control processor 22 the switched live SW output from the connector 10 is switched on and off down line of the switch 7. In a variation of the circuit shown, the live L is also fed through the relay 28 so that in the event that the switch 7 is in its off position, the switched live SW output from the connector could -nevertheless be switched on and off. This arrangement can be used to great advantage.For example if the cooperating device is a pendant lamp holder, a light fitted thereto would flash on and off upon detection of a hazardous gas condition. This would help to increase the awareness and attention of deaf or partially deaf people to a hazardous condition.

The switched live SW is also input to the control processor 22 via the line 29. The control processor 22 is configured to respond to power on the line 29 being switched on and off in predetermined patterns.

Thus, switching the power on and off three times in rapid succession, for example, will cause the control processor 22 to enter its self-test mode and switching the power on and off five times, for example, will cause the control processor to enter a standby mode in which it is non-responsive to the detection of hazardous gas conditions by the detector 24. This latter feature could be useful during the site maintenance in, say, an office or an hotel room where dust and debris is created possibly causing a false hazardous condition to be created.

It is well known that data can be transmitted over the mains by using the mains signal as a carrier and modulating the carrier to convey data. This concept is incorporated into the circuit 16 by way of an induction loop 30 or other suitable interface from the control processor 22. The provision of the induction loop 30 enables the detector to be used as part of a larger alarm system in which several independent detectors communicate with a central controller and/or with each other via the mains supply 6. In response to the detection of a hazardous gas condition, the control processor 22 transmits a signal via the loop 30 and the mains supply 6. On receipt of such a signal other control processors in other smoke detectors respond by activating their own alarms 25 and lamps 26 and the central controller (not shown) responds by automatically dialling the emergency services.Details on the exact implementation of such an arrangement are well within the ability of those possessed of the relevant skills and will not be described in any further detail herein.

By using the existing lighting wiring circuit it is easy to install the above described smoke detector into existing buildings without the need for extensive rewiring of the building beforehand. The use of a standard form of ceiling rose provides greater flexibility by enabling either a cooperating device or an alarm or both to be fitted thereto without any other modification.

Whilst in the foregoing description the described cooperating device is a light fitting it will be appreciated that other devices may be used. For example an intruder detector could instead be fitted.

Indeed, the cooperating device could simply be a blanking panel to close off the associated female connector 10 from prying fingers and to give an aesthetically pleasing finish to the smoke detector.

Furthermore, whilst the foregoing description has been given with reference to a smoke detector it will be appreciated that the same could be replaced by any suitable gas detector. Indeed, the detector could be a movement detector forming part of a larger intruder alarm system whose constituent parts communicate with each other via the mains supply. Similarly, the detector could be arranged to communicate automatically with other devices, for example an hotel bell/call switch, in the event of a hazardous condition being detected.

Having thus described the present invention by reference to a described embodiment it is to be well understood that the embodiment in question is exemplary only and that modifications and variations such as will occur to those possessed of appropriate knowledge and skills may be made without departure from the spirit and scope of the invention as set forth in the appended claims and equivalents thereof.

Claims (17)

CLAIMS:

1. A detector comprising: a housing; an associated male connector in said housing for mounting the alarm to an independent cooperating female connector such that in use the male connector receives electrical power from and the detector is demountably supported by the female connector; an electrical detection circuit connected to receive electrical power from the male connector; and an associated female connector in said housing connected to receive electrical power from the male connector and adapted for supporting and supplying electrical power to a cooperating device mountable thereto.

2. A detector as claimed in claim 1, wherein the associated male connector is adapted to connect to an independent female connector comprising a fixed ceiling rose and the associated female connector is adapted to connect to an independent male connector connectable to a light fitting.

3. A detector as claimed in claim 1 or 2, wherein the associated female connector is similar in form to the independent female connector.

4. A detector as claimed in claim 1 or 2 or 3, wherein the associated male connector is adapted to receive mains power from the independent female connector by way of at least live and neutral connections.

5. A detector as claimed in claim 4, wherein said electrical circuit comprises a gas detector, an alarm and a control processor responsive to the gas detector for activating the alarm.

6. A detector as claimed in claim 5, wherein said electrical circuit comprises a transformer connected to said live and neutral connections and a rectifier connected to said transformer for providing DC power to the circuit.

7. A detector as claimed in claim 6, further comprising a rechargeable battery connected to receive power from the rectifier, the control processor being arranged to receive power from the battery in the event of a failure of power from said independent female connector.

8. A detector as claimed in claim 5 or 6 or 7, wherein said alarm comprises an audible warning device.

9. A detector as claimed in any of claims 5 to 8, wherein said alarm comprises a visible warning device.

10. A detector as claimed in any of claims 4 to 9, wherein the associated male connector is adapted to receive mains power by way of a switched live connection.

11. A detector as claimed in any of claims 4 to 10, wherein the associated female connector comprises equivalent connections to those provided to said associated male connector.

12. A detector as claimed in claim 11 as dependant on claims 5 and 10, wherein said electrical circuit comprises a normally closed switch between the switched live connection of the associated male connector and the corresponding connection of the associated female connector, the control processor being arranged to activate the switch in response to the gas detector such as to cause pulsing of power from the switched live connection from the associated female connector.

13. A detector as claimed in any of claims 5 to 12, further comprising a test button, the control processor being responsive to said test button to activate the alarm.

14. A detector as claimed in any of claims 5 to 12, wherein said control processor is connected to the switched live connection of the associated male connector and is responsive to pulsing of power from the switched live connection of the associated male connector to activate the alarm.

15. A detector as claimed in any of claims 5 to 14, wherein said gas detector is responsive to smoke.

16. A detector as claimed in any of claims 4 to 15, further comprising an interface between said control processor and said live and neutral connections from the associated male connector for applying signals to said mains power for transmission to a remote central controller.

17. A detector substantially as described herein with reference to the accompanying drawings.