WO1991010980A1

WO1991010980A1 - Coupling system for smoke detector units

Info

Publication number: WO1991010980A1
Application number: PCT/FI1991/000001
Authority: WO
Inventors: Kari Kuitunen; Terho Westman
Original assignee: Oy Sapal Security Ltd.
Priority date: 1990-01-15
Filing date: 1991-01-02
Publication date: 1991-07-25
Also published as: FI83140C; AU6909491A; CA2073854A1; FI83140B; FI900209A0

Abstract

The invention relates to a coupling system for smoke detector units, said system comprising a plurality of smoke detector units (1) having their outgoing alarm signal wires (9) coupled to one or a plurality of common alarm and/or signalling devices (1, 4; 13). At least some of the alarm signal wires (9) extending from smoke detector units (1) are fitted with a diode (10) or a like current-directing element which is coupled to permit the passage of alarm signal current away from unit (1) but to prevent the alarm signal current from reaching said unit (1). Downstream of said diodes (10) or like current-directing elements said alarm signal wires (9) are joined together to provide a joint alarm signal wire (9) for a plurality of smoke detector units (1). All smoke detector units can be connected by way of a joint alarm signal wire to a common central alarm device (13).

Description

Coupling system for smoke detector units.

The present invention relates to a coupling system for smoke detector units, said system comprising a plurality of smoke detector units having their outgoing alarm sig¬ nal wires coupled to one or a plurality of common alarm and/or signalling devices.

It is prior known to couple the alarm signal wires coming out of a plurality of smoke detector units to¬ gether or to a plurality of common alarm or signalling devices in order that an alarm be detected even in the case that there is no one present in the room or apart¬ ment which contains the smoke detector unit issuing the alarm. This provides an essential improvement on monitoring efficiency in hotels, apartment buildings, semidetached houses etc. However, the prior known coupling systems involve also substantial drawbacks and defects. When the alarm signal wires of several units are coupled together, all units will produce an alarm as the detector of a single unit is activated. Since most of the alarms are false (resulting from blowing tobacco smoke into a detector, pressing the unit test¬ ing button, device malfunction etc.) , this prior known coupling system causes unreasonable disturbance. A prior known method of avoiding this is to pull an alarm wire from each detector unit separately to a central alarm device. However, this results in an enormous number of wire pullings and, in addition, the system is limited to putting out an alarm in just a single central alarm device.

An object of the invention is to provide an improved coupling system which is capable of eliminating the above-mentioned drawbacks and shortcomings. A particular object of the invention is to provide a coupling system, wherein an alarm sent out by any one of the smoke detector units can be delivered selective¬ ly to any other desired smoke detector units and/or to

a central alarm device by way of a single common alarm signal wire.

This object will be achieved on the basis of the charac¬ terizing features set forth in the annexed claim 1.

The preferred embodiments of the invention are set forth in claims 2-7.

The invention will now be described in more detail with reference made to the accompanying drawing which il¬ lustrates a wiring diagram for a coupling system of the invention.

The drawing shows three pieces of smoke detector units 1 which as such are conventional, commercially available devices having their circuit components mounted on a card 2 which also carries a smoke detector 3 and an alarm 4 which in operation sends out e.g. periodically repeated sound signal. Unit 1 includes also a led 5 which indicates the operating condition of a unit and its coupling to a power source. Led 5 can also be pro¬ vided with a testing button, the pressing of which activates alarm 4 to produce a sound alarm.

Each unit is parallel coupled by way of wires 8 to a common power source which comprises a transformer 6 , connected to an alternating-current mains and secured by means of an accumulator or a battery 7. The wires 8 carry a direct-current voltage of e.g. 9 - 12 V. As smoke comes into contact with detector 3 , alarm 4 produces a sound signal. At the same time, an alarm signal wire 9 is provided with a low-current alarm sig- nal voltage. Accordingly, if alarm signal wire 9 car¬ ries a corresponding alarm signal voltage from outside, alarm 4 produces a sound signal even though detector 3 has not indicated detection. Based on this, the alarm signal wires 9 of all units 1 can be coupled together, whereby an alarm from one unit produces an alarm from all units.

An insight in this invention is, however, to place in alarm signal wire 9 a diode 10 which permits the pass¬ age of alarm signal current away from unit 1 but pre¬ vents the alarm signal current from reaaching the card 2 of unit 1. Thus, it has been possible to couple the alarm signal wires 9 downstream of diodes 10 so as to form a combined alarm signal wire without trans¬ ferring the alarm of one unit 1 over to another unit fitted with a diode 10. Simply by constructing one of the units 1 without a diode 10 it is possible to select any unit 1 to serve as an alarming unit which always sends out an alarm regardless of which unit the alarm is coming from. Thus, in an apartment building or semi¬ detached house it is possible to choose one or several apartments for setting off an alarm in addition to the apartment in which the detection has occurred. Further¬ more, the same combined alarm signal wire 9 can be passed to a central alarm device 13 which always sets off an alarm whenever any of the detector units 1 is alarmed.

In order to locate the signalling smoke detector unit 1 as quickly as possible from the hallway, there is a signal lamp mounted above the outer door of each room or apartment, said lamp receiving its power supply from wires 8 and having a transistor 12 serving as its cur¬ rent switch, the base of which is connected by way of a wire 129 to alarm signal wire 9 between diode 10 and a circuit mounted on card 2. Hence, said signal lamp 1 is only switched on when its associated unit 1 sets off an alarm. In other words, although a plurality of units 1 are coupled with a common alarm signal wire 9, the only signal lamp 11 to be switched on belongs to the unit whose detector 3 indicates a detection.

In order to facilitate the selection of concurrently alarming units 1 it is possible to construct alongside all diodes 10 a shunt circuit fitted with an ON/OFF switch 15. In the accompanying drawing this has only been shown in one (last) unit 1. However, this re¬ quires that a wire 129 connected to the base of tran¬ sistor 12 be coupled to receive its control directly from the circuit of detector 3 , whereby an alarm sig¬ nal coming in from outside from wire 9 does not switch lamp 11 on.

In the illustrated case, the base of a transistor switch 12 associated with the power supply circuit of central alarm device 13 is coupled through the inter¬ mediary of a delay means 14 to a combined alarm signal wire 9 of the smoke detector units. The purpose of delay means 14 is to prevent a false alarm which may result e.g. from pressing the test button of one of the units or from momentary detection e.g. as a result of blowing tobacco smoke from close range directly into detector 3. In a similar fashion, it is of course possible to couple delay circuit 14 to the control wire 129 of each transistor 12. A manual switch 15 can be used for shutting the power supply circuit of alarm siren 13.

A coupling system of the invention only requires three wires or conductors between each unit 1. Between a power source 6, 7 and the closest unit 1 or a terminal box 17 there are just two wires required. Also the central alarm device 13 is satisfied with three wires.

It is obvious that the invention is by no means limited to the above-described exemplary embodiment but a corresponding selectively alarming and alarm-site indicating coupling system can be designed by using most varying circuit elements. A diode 10 and a tran¬ sistor 12 can be just as well placed on card as a part of the coupling between other circuit elements of the unit. A signal lamp 11 can be replaced with a sound signal siren or buzzer. There may be a pluality of central alarm devices 13 and all units 1 can be fitted with a diode 10, whereby just one or several central alarm devices 13 send out an alarm.

Claims

1. A coupling system for smoke detector units, said system comprising a plurality of smoke detector units (1) having their outgoing alarm signal wires (9) coupled to one or a plurality of common alarm and/or sig¬ nalling devices (1, 4; 13) , c h a r a c t e r i z e d in that at least some of the alarm signal wires (9) extending from smoke detector units (1) are fitted with a diode (10) or a like current-directing element which is coupled to permit the passage of alarm signal current away from unit (1) but to prevent the alarm signal current from reaching said unit (1) , and that said alarm signal wires (9) are downstream of the current-directing elements combined together to provide a joint alarm signal wire (9) for a plurality of smoke detector units (1) .

2. A coupling system as set forth in claim 1, c h a r - a c t e r i z e d in that said joint alarm signal wire

(9) of smoke detector units (1) is connected to a common central alarm device (13) .

3. A coupling system as set forth in claim 1 or 2, c h a r a c t e r i z e d in that above the location, e.g. a door, of each smoke detector unit (1) is mounted a signalling device (11) having the control wire (129) of its current switch (12) coupled with alarm signal wire (9) between a diode (10) and the circuit of smoke detector unit (1) , whereby said signalling device (11) is only activated when its associated smoke detector unit (1) sends out an alarm.

4. A coupling system as set forth in any of claims 1 - 3, c h a r a c t e r i z e d in that the joint alarm signal wire (9) of the smoke detector units connects with at least one smoke detector unit direct¬ ly without said diode (10) or a like current-directing element, whereby that particular smoke detector unit (1) sends out an alarm every time any of the smoke detector units (1) included in the coupling system sends out an alarm.

5. A coupling system as set forth in any of claims 1 - 4, c h a r a c t e r i z e d in thatsaid smoke detector units (1) are parallel coupled with a common current source (6, 7) and that said central. alarm device (^"13) as well as signalling devices (11) of each unit are adapted through the intermediary of a semi¬ conductor switch element (12) to receive their power supply from said current source (6, 7) .

6. A coupling system as set forth in claim 2, c h a r a c t e r i z e d in that the base of a transistor switch (12) associated with the power supply circuit of central alarm device (13) is coupled through the intermediary of a delay means (14) to the joint alarm signal wire (9) of smoke detector units (1) .

7. A coupling system as set forth in claim 1 or 4 , c h a r a c t e r i z e d in that alongside said diode (10) or a like is provided a shunt circuit fitted with an ON/OFF switch (15) .