GB2289968A

GB2289968A - Alarm with test function

Info

Publication number: GB2289968A
Application number: GB9510662A
Authority: GB
Inventors: Wolfgang Blaschke
Original assignee: Zettler GmbH
Current assignee: Zettler GmbH
Priority date: 1994-05-31
Filing date: 1995-05-25
Publication date: 1995-12-06
Anticipated expiration: 2015-05-25
Also published as: AT807U1; DE9408898U1; ES2108635B1; GB9510662D0; GB2289968B; ES2108635A1

Abstract

A hazard warning alarm is provided, particularly for use as a fire alarm, intended to be part of a hazard warning system in which a plurality of similar hazard alarms are connected to a control station. The hazard alarm comprises a manually actuatable alarm switch (3) and alarm circuit housed in a casing so that when the switch is actuated and the alarm circuit is in its stand-by mode, a warning will be given at the control station. Each hazard alarm can be switched individually between the stand-by mode and a test mode by mode-switching means (19, Fig. 2 not shown) capable of being actuated from outside the casing so that an operational check can be made on each individual hazard alarm, while the other alarms remain in their stand-by mode. The external actuation may be carried out using a portable magnetic unit (7), a remote transmitter, a key-operated switch or an external keypad. <IMAGE>

Description

The invention relates to a hazard alarm, in particular a fire alarm, for a hazard alarm system, in which a plurality of hazard alarms is connected to a control station, the hazard alarm comprising an alarm switch to be actuated manually and an alarm circuit located in an alarm casing and to be connected to the control station, which alarm circuit, in an alarm stand-by mode, upon actuation of the alarm switch, activates a hazard alarm in the control station, the actuation of the alarm switch in test mode bringing about an operational check of the system comprising the alarm including its alarm switch and the control station.

Known hazard alarms of this type must be checked at regular intervals. In addition to checking the alarm circuit, the control station and the connection between the alarm and the control station, it is of particular significance that the alarm switch to be actuated manually is checked, i.e. is actuated manually, for which purpose it is necessary to visit the location of the alarm. To avoid a false alarm at the time of such an operational check, the hazard alarm system is switched from the alarm stand-by mode, in which the actuation of the alarm switch leads for example to the fire brigade or the police being alerted, into a test mode.

In this case it is known, from the control station, to switch all the connected hazard alarms, or however a certain group of hazard alarms, to the test mode, whereupon the alarm switches of the individual alarms can be actuated for the purpose of their functional check.

However, previously, for each of the hazard alarms to be checked, it must be made clear that these alarms are not in the alarm stand-by mode and that an actuation of the alarm switch would not lead to the actuation of an alarm. Otherwise the danger exists that a person, who wishes to actuate an alarm, attempts to do this from an alarm which is in the test mode and is satisfied with this attempt, since the person does not recognise that the actuation of the alarm switch is not alerting anyone. However, such a situation is precluded by identifying the hazard alarm which is in the test mode, for example by providing a corresponding identification plate.

Solely after such an identification of all the alarms to be checked, can the switch to the test mode be made from the control station, after which the individual alarms are checked by actuating the respective alarm switch of the respective alarm.

After the operational check is completed, in order to put the installation back into operation, there is a switch in the control station from the test mode to the alarm stand-by mode and the identification of the test mode at the individual alarms is removed.

Thus, with this known test method with conventional hazard alarms, each alarm must be visited three times, resulting in a very time-consuming and labour-intensive test method and a relatively long down time, which is dangerous due to the enforced alternative of other slower possibilities of alerting the authorities.

It is therefore the object of the invention to provide a hazard alarm of the aforementioned type, which allows a less timeconsuming and thus less risky functional check than conventional alarms.

This object is achieved by a hazard alarm of the type defined at the beginning, which comprises mode-switching means able to be actuated from outside its closed alarm casing, by which the system for this alarm solely can be switched between the alarm stand-by mode and the test mode.

According to the invention, for this alarm solely, it is possible to switch to the test mode, whereby the other hazard alarms are thus able to remain in the alarm stand-by mode. There is thus no compulsion, before the actual operational check, to identify an entire group of hazard alarms or all the hazard alarms as "out of operation" and then to once more remove this identification after the operational checking of all the hazard alarms has been carried out. Since, according to the invention, only one hazard alarm is respectively in the test mode, i.e. out of alerting operation, the hazard alarm system formed from such hazard alarms, apart from only one alarm, is always on the alert.In order to increase the alarm readiness period, it is also a contributing factor that the hazard alarm according to the invention can be switched over from outside its closed alarm casing, i.e. can be switched into the test mode and back again into the alarm stand-by mode simply and quickly.

It is conceivable to actuate the mode-switching means for example by way of a keyboard provided on the alarm casing, in which case a certain code can be provided for switching the modes, in order to prevent unauthorised or accidental abandonment of the alarm stand-by mode. However, the mode-switching means can advantageously be actuated by a portable mode control unit separate from the alarm. Due to this it is possible to equip solely the person entrusted with the functional check, with a mode control unit and thus with the authorisation for switching off the alarm stand-by mode.

If the mode control unit comprises positioning stops associated with the alarm casing, by means of which it can be brought into an actuating position actuating the mode-switching means, when applied against the alarm casing, the switching to the test mode is possible in a reliable and thus rapid manner.

The hazard alarm can be constructed so that the alarm switch is secured by securing means, in particular a pane of glass, which have to be overcome manually for actuating the alarm and the securing means can be moved into a position intended for the actuation of the alarm switch by release means able to be introduced from outside through an insertion opening into the closed alarm casing and that the mode control unit applied against the alarm casing forms a mask releasing the insertion opening solely in the actuating position of the mode control unit for the release means. Due to this the manual actuation of the alarm switch is only possible if the alarm stand-by mode has been relinquished. In this particularly preferred embodiment, a mistaken actuation of an alarm at the time of a functional check is precluded with great certainty.

When the mode control unit is accidentally left in its actuating position, in order to prevent the omission of switching back into the alarm stand-by mode at the end of the operating check, it may be provided that the mode control unit has an outer contour which cannot be applied in a self-holding manner against the alarm casing without external retaining forces. Due to this measure, during the operational check, the mode control unit must be held against the alarm casing consciously by the person carrying out the test. As soon as the person carrying out the test releases the mode control unit, the latter detaches from the alarm casing and consequently causes switching-back to the alarm stand-by mode.

In order to prevent the hazard alarm from remaining in the test mode after the operational check and that this is not noticed in the case of danger by a person wishing to activate the alarm, it will be considered that the mode control unit is shaped so that in the actuating position actuating the mode-switching means, it covers at least partly towards the outside, the access to the alarm casing intended for manual actuation of the alarm switch in the alarm stand-by mode. This is achieved for example in the case of an alarm switch covered by a pane of glass, due to the fact that in its actuating position, the mode control unit covers the pane of glass. Even if the mode control unit should have been forgotten and should possibly be left in its actuating position it is obvious to everyone and can be made even more clear by a corresponding reference on the mode control unit, that the mode control unit must be removed in order to gain access to the alarm switch, whereby an automatic switching-back to the alarm stand-by mode is involved. This opens up the possibility of constructing the mode control unit as self-retaining on the alarm casing without the aforementioned risk of an ineffective actuation of the alarm, to facilitate its handling.

The mode-switching means and the mode control unit can be produced in a particularly simple manner due to the fact that the mode-switching means comprise a magnetic field-sensitive member and the mode control unit comprises a permanent magnet. The magnetic field-sensitive member may be, for example, a Reed contact, a Hall element or a magnetic field-dependent resistance.

This also opens up the possibility of converting already existing hazard alarms at relatively low cost into a hazard alarm according to the invention, which comprises mode-switching means able to be actuated in a particularly reliable manner.

It is however also conceivable that the mode control unit is constructed as a transmitter using wireless transmission and the mode-switching means comprise a receiver responding to the transmitter, the transmitter being able to be constructed as an infra-red transmitter and the receiver as an infra-red receiver.

The receiver may in this case be for example a photodiode or a phototransistor accessible through an opening in the alarm casing. The construction of the mode control unit as a portable, battery-operated transmitter does not make application and exact positioning of the mode control unit on the alarm casing necessary. Due to the use of infra-red signals, the possibly disturbing influence of visible light can be prevented.

In order to preclude external disturbance influences as completely as possible, for the actuation of the mode-switching means, the mode control unit may transmit a coded signal, to which the receiver specifically responds. From this point of view, it may even seem useful to construct a mode control unit constructed as a transmitter as a shaped part conforming to the shape of the alarm casing, due to which a reliable actuation of the mode-switching means can be guaranteed even at very low transmitting power. Other transmission means, for example inductive means, are also conceivable for actuating the modeswitching means.

The mode control unit may be particularly convenient if it is provided that the mode-switching means comprise a key-operated switch, whereof the key insertion slot is accessible from outside the alarm casing, and that the mode control unit is a key actuating the key-operated switch. In this case, the modeswitching means may comprise a conventional lock cylinder or, however, also a card reader reading a chip card.

If the alarm comprises indicators indicating the actuation of the mode-switching means optically or acoustically, the person carrying out the test may ascertain positively whether switching to the test mode has occurred, before they proceed with the manual actuation of the alarm switch, due to which a further protection against a false alarm is provided. The optical indicator may in this case be combined with an alarm indicator, which is frequently provided anyhow.

Since it may be possible, despite correct actuation of the modeswitching means, that the control station is still in the alarm stand-by mode, it may be advantageous if the alarm comprises indicators indicating optically or acoustically a confirmation of the control station about the existence of the test mode.

If the alarm comprises indicators indicating optically or acoustically the result of the functional check, then the person carrying out the check may decide directly whether the hazard alarm is to be once again set in operation or exchanged or put out of operation.

A further safeguard against a false alarm initiated by the operational check is provided if the alarm sends a test signal to the control station, upon actuation of the alarm switch in the test mode, which signal differs from the alarm signal sent in the alarm stand-by mode. In such an embodiment, the control station does not need to have any special switching means, it must solely be able to distinguish the alarm signal from the test signal.

In this case it is appropriate for carrying out the functional check, if the alarm comprises indicators, which indicate optically or acoustically the answer-back signals from the control station relating to the receiving of the test signal.

The aforementioned indicators may naturally be combined or united in one means. Thus, for example, the switching-on of the indicator may indicate that the control station has correctly received the test signal and the subsequent switching-off of the indicator may indicate that the operational check for this hazard alarm can be terminated. Further information can also be displayed by using flashing lights and steady light.

The invention also relates to a mode control unit with one or more of the listed mode control unit features for a hazard alarm, which comprises one or more of the features of the invention.

The invention furthermore relates to a hazard alarm system with a control station and a plurality of hazard indicators of the aforedescribed type connected to the latter for the transmission of an alarm to the control station.

According to a further point of view, the invention also relates to a method for the operational checking of a hazard alarm system comprising a plurality of hazard alarms connected to a control station, with alarm switches to be actuated manually, in particular a fire alarm system, in which the system for functional checking also comprising the alarm switches, is switched from an alarm stand-by mode into a test mode and the alarm switch is actuated, the system respectively solely for one alarm alone being switched by this alarm from outside its closed alarm casing, into the test mode, whereas for the remaining alarms it is left in the alarm stand-by mode.

Due to this method according to the invention, the duration of the operational check of a hazard alarm system according to the invention can be considerably shortened, since the identification of the alarms as being in the test mode and the removal of the identifications necessary after the operational check is completed, may be dispensed with. Furthermore, during this method, apart from in each case only one hazard alarm, the hazard alarm system remains fully on stand-by.

The invention will be described hereafter with reference to embodiments, referring to the drawings, in which: Figure 1 is a perspective view of a hazard alarm according to the invention, Figure 2 is a diagrammatic view of the hazard alarm according to the invention of Figure 1 in conjunction with a hazard alarm system shown diagrammatically and Figures 3 to 6 show further embodiments of the hazard alarm according to the invention.

In Figure 1, the reference numeral 1 designates a hazard alarm according to the invention, which comprises an alarm switch 3 to be actuated manually in the case of a hazard. In an alarm standby mode, the actuation of the alarm switch 3 initiates a hazard alarm in a control station connected to the alarm 1. For an operational check, in which the alarm switch 3 is actuated manually, one must switch into a test mode in order to avoid a false alarm. Serving for this purpose is a mode control unit 7 shown fitted to an alarm casing 5 in Figure 1.

In this special embodiment of the hazard alarm 1, the alarm switch 3 is protected from mistaken actuation by its location in a rectangular recess 11 covered by a pane of glass 9 serving as the security means. These security means 9 must be overcome manually before tripping the alarm, for example by a hammer (not shown) located on the alarm casing, in order then, by pressing the alarm switch 3 constructed as a push button, to be able to initiate an alarm.

However, the alarm switch may also be a push button 13 pushed into the alarm casing by the pane of glass 9 located in the security position, normally against its spring tension, which push button is illustrated in Figure 1 in dot-dash line in a position corresponding to the broken or removed pane of glass 9.

It is possible to combine the push buttons 3 and 13 in a redundancy increasing the alarm tripping reliability or to use them as alternatives.

Before the operational checking of the alarm switch 3, it is necessary to switch from the alarm stand-by mode by means of the mode control unit 7 into the test mode. With an operational check of this type, due to a key 15 shown in broken line, able to be introduced into an opening in the alarm casing and serving as the release means, the pane of glass 9 can be brought out of its securing position into a position shown in broken line, allowing actuation of the alarm switch 3.

In this embodiment, the mode control unit 7 is constructed as an angular member intended for covering a corner of the alarm casing 5, which comprises positioning stops formed by its side faces 7a, 7b, 7c. This angular member 7 comprises a permanent magnet 17 at a position actuating the mode-switching means when the angular member bears against the alarm casing 5.

As shown in Figure 2, in this case the permanent magnet 17 is located in the vicinity of a magnetic field-sensitive member, in this case a Reed switch 19 located inside the alarm casing 5.

Due to the spatial proximity of the permanent magnet 17 to the Reed switch 19, determined in this position of the mode control unit 7, which Reed switch is connected to an alarm circuit 21 comprising mode-switching means 20, this alarm circuit 21 is closed. This has the result that upon actuation of the alarm switch 3, instead of an alarm signal, a test signal is emitted on a twin-wire alarm lead 25 connecting a plurality of similar hazard alarms la, lb in series to a control station 23. However, it is also possible that by closing the Reed switch 19 a mode switching signal is sent to the control station 23, which has the result that despite an alarm signal emitted by the alarm 1, there is no alarm actuation in the control station 23.

An indicator 27 constructed for example as an L.E.D. or an acoustic signalling means, which is switched on when the Reed switch 19 is closed, indicates the existence of the test mode.

However, the indicator 27 may also be switched from the control station 23, if the control station has for example received the test signal or is located in the test mode. In this case, for example the switching-off of the indicator 27 controlled by the control station 23 may indicate that the operational checking of the hazard alarm 1 is terminated and the latter can again be switched to the alarm stand-by mode.

The mode control unit 7 illustrated in Figure 1 in its position fitted to the alarm casing 5, comprises such a weight distribution that without additional holding by the person carrying out the test, it would fall from the alarm casing 5 and thus re-establish the alarm stand-by mode.

Variations of the hazard alarm of Figures 1 and 2 are illustrated in Figures 3, 4, 5 and 6, in which case corresponding components are designated by the same reference numerals respectively increased by the number 100, 200, 300 or 400.

In the hazard alarm 101 illustrated in Figure 3, the mode control unit 107 covers the access to the alarm switch by a covering surface 108, in the actuating position actuating the modeswitching means, on the alarm casing 105. Thus if a person carrying out the test leaves the mode control unit 107 on the hazard alarm 101 and thus forgets to switch back to the alarm stand-by mode, an actuation of the alarm switch not leading to the initiation of the alarm, is not possible. Before the transmission of the alarm, the mode control unit 107 must namely be removed from the alarm casing 105 for allowing access to the alarm switch, due to which there is necessarily a switch to the alarm stand-by mode.

In addition, the mode control unit 107 is constructed as a mask provided with an opening 116, which does not cover an insertion opening 118 for release means 115 bringing the pane of glass 109 out of its securing position solely when the permanent magnet 117 is in a position enforcing the test mode.

Figures 4, 5 and 6 show further embodiments, which differ from that shown in Figure 1, in each case due to other mode control units. In Figure 4, the mode control unit is shown as a convenient infra-red transmitter 207, which preferably transmits coded infra-red mode-switching signals to an infra-red receiver 220 included in the mode-switching means, in the alarm casing 201.

The hazard alarm 301 of Figure 5 can be switched between the alarm stand-by mode and test mode by way of a keyboard located on the alarm casing 305, by keying-in a code number.

In Figure 6, the mode control unit is a key 407 able to be inserted into a key insertion slot of a key-operated switch belonging to the mode-switching means.

Claims

CLAIMS:

1. A hazard alarm adapted to be connected with one or more similar alarms to a control station, the alarm comprising a casing having a manually actuatable alarm switch and an alarm circuit which, when in its alarm stand-by mode, activates an alarm at the control station upon actuation of said switch, said circuit also having a test mode to enable an operational check to be made and mode-switching means capable of being actuated from outside the casing to switch the alarm between its stand-by mode and test mode.

2. Hazard alarm according to claim 1 wherein the mode-switching means is able to be actuated by a portable mode control unit separate from the alarm.

3. Hazard alarm according to claim 2 wherein the mode control unit comprises positioning means associated with the alarm casing, by means of which it can be brought into an actuating position for actuating the mode-switch means when applied against the alarm casing.

4. Hazard alarm according to claim 3 wherein the alarm switch is secured by securing means which has to be overcome manually for actuating the alarm and wherein the securing means can be moved into a position intended for the actuation of the alarm switch by release means able to be introduced from outside through an insertion opening in the alarm casing, and wherein the mode control unit when applied against the alarm casing forms a mask releasing the insertion opening solely in the actuating position of the mode control unit for the release means.

5. Hazard alarm according to claim 3 or 4 wherein the mode control unit has such a shape or weight distribution that it cannot remain in contact with the casing in the absence of external retaining means.

6. Hazard alarm according to any one of claims 3 to 5 wherein the mode control unit is shaped so that in the actuating position actuating the modeswitching means, it covers at least partly access to the alarm casing required for manual actuation of the alarm switch in the alarm stand-by mode.

7. Hazard alarm according to any one of claims 2 to 6 wherein the mode-switching means comprises a magnetic field-sensitive element and the mode control unit comprises a permanent magnet.

8. Hazard alarm according to any one of claims 2 to 6 wherein the mode control unit includes a radio transmitter and the mode-sxnitching means comprises a receiver responsive to the signals from the transmitter.

9. Hazard alarm according to any one of claims 2 to 6 wherein the mode control unit includes an infra-red transmitter and the mode switching means includes an infra-red receiver responsive to signals from said transmitter.

10. Hazard alarm according to claim 8 or 9 wherein for actuating the mode-switching means the mode control unit is adapted to send a coded signal, to which the receiver is specifically responsive.

11. Hazard alarm according to claim 2 wherein the mode-switching means comprise a key-operated switch, whereof the key insertion slot is accessible from outside the alarm casing and wherein the mode control unit is a key actuating the key-operated switch.

12. Hazard alarm according to any one of claims 1 to 11 wherein the alarm comprises indicators indicating optically or acoustically the operating state of the mode-switching means.

13. Hazard alarm according to any one of claims 1 to 12 wherein the alarm comprises indicators indicating optically or acoustically a confirmation by the control station of the existence of the test mode.

14. Hazard alarm according to any one of claims 1 to 13 wherein the alarm comprises indicators indicating optically or acoustically the result of the functional or operational check.

15. Hazard alarm according to any one of claims I to 14 wherein the alarm is adapted to send a test signal to the control station, upon actuation of the alarm switch in the test mode, which signal differs from the alarm signal sent in the alarm stand-by mode.

16. Hazard alarm according to claim 15 wherein the alarm comprises indicators which optically or acoustically indicate the answer-back signals from the control station relating to the receiving of the test signal.

17. Mode control unit according to any one of claims 2 to 11 for a hazard alarm according to any one of claims 1 to 16.

18. Hazard alarm system which comprises a control station and a plurality of hazard alarms connected to the latter for sending an alarm to the control station, each said hazard alarm being in accordance with any one of claims 1 to 16.

19. A method for operational checking of a hazard alarm system wherein a plurality of hazard alarms are connected to a control station and wherein each hazard alarm is manually actuatable, said method comprising testing an individual hazard alarm by switching it from an alarm stand-by mode to a test mode using mode switching means effective from outside said hazard alarm, while the other hazard alarms remain in their alarm stand-by mode.