GB2217888A - Locally sited intruder alarm signal and fault indicator unit - Google Patents

Abstract

The unit is generally in the form of a small junction box which is practicable for fitting directly to individual protecting devices such as is fitted to windows in the form of tubes containing wires and built into a frame to cover the window, or weak partitions and doors which are covered in a wire network or any other detection device that does not of it's own accord incorporate an indication denoting the condition of the device being meant to provide protection. A light emitting device 12 is provided in the unit to indicate when the protecting device coupled to the unit has operated and a relay 14 is provided to signal such operation to a control monitoring station. <IMAGE>

Description

LOCALLY SITED INTRUDER ALARM SIGNAL AND FAULT INDICATOR This invention relates to a unit to provide localised self- indication of intermittent faults and the indication and relaying of alarm conditions in those @ intruder alarm detection devices not normally provided with integral self-indication.

Intruder alarm systems usual ly provide indication of te condition Of the intruder detection part oo the system hv indicator lights on the master control unit. Each light usually indicates a zone or section of the whole system, which may be divided into several zones or sections according to the size and complexity of the system. Because master control units increase in price in relation to the number of zones they can indicate separately, and because eac zone requires a separate cable, it is common practice to place several separate detection devices on one zone, which results in only one indicator light displaying the state or condition of possibly man detention devices grouped together.

An example of such detection devices which are often grouped together are rows of windows, each window being protected with frame containing closely spaced tubes inside which detection wires are concealed. Each frame usually is fitted with a junction box to connect it to the system, the whole group is then connected to the same indicator light on the master control panel, thus no information is given as to which window was the cause of indication at the control unit. If the indication was caused by an abnormal fault in a detection device, tracing the fault is often time consuming and costly.

However, there are many detection devices, some known collectively as Space Detectors, of which an infra-red body heat detector is an example5 which are provided with integral indication usually by means of a light which often remains lit following upon a detection. A group of these can be connected to one of the zone indicator lights on the master control units but in this case the detection device causing indication can be easily found due to it's ability to give self-indication.

According to the present invention, this facility which aids in the tracing of faults and the location of points of illegal entry, can be made available to those detection devices that do not incorporate a localised indicator light and where desired, also replace the junction box if one would have been fitted.

according to the present invention1 there is provided an electrically operated devices comprising circuitry which is able to sense and react to certain electrical conditions in a single intruder alarm detection device which is connected to it, provide visible indication of that condition, and output electrical indication of this back to the master control unit for processing. It incorporates an ability to indicate during a test routine, certain faults which could lead to false alarms.

It is intended to operate with any control apparatus that is capable of responding to the opening or the closing of a pair of dry contacts, or any other familiar means of outputting a signal as may be included in the output part of the invention.

It is intended that the device and it S casing be of sufficient small dimensions that it may, where desired, take the place of the connection junction boxes usually fitted to the type of detection device for which it provides indication and could thus be described as an indicating junction box.

A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawing in which: Figure 1 shows an electronic circuit suitable for carrying out the electrical requirements of the whole device.

Figure 2 illustrates a typical appearance of the device 18 with it's indicator light 17 when fitted to a frame holding tubes 19 and acting also as the junction box usually fitted.

Figure 3 illustrates the device 21 when fitted at or beside a door frame, the door 20 itself being laced over with fine wire and as is mostly the case, this protecting wiring being hidden and covered with some form of boarding. 23 shows a flexible connecting wire and a normal junction box arranged to take the the fine protection wiring to the invention 21 with it's indicator light 22.

Referring to the drawing, the self indicating junction box comprises a suitable circuit arrangement as shown in Fi l= with facility for connections 2, 3, 4 and 5 to the detection device which is to be provided with local indication and facility for connection 10 and 11 to the zone detector/indicating part of a control unit, and contained within an enclosure Fig. 2. 18 and Fig 3. 22 in the form and approximate size of a normal alarm system junction box and incorporating a visible lit indicator Fig 2. 17 and Fig 3. 22.

The circuit diagram in Fig 1. demonstrates a typical form of protection where a protecting wire which must not be broken, has it's ends connected to 2 and 3 thus shorting these two points. Another protecting wire similarly shorts 4 and 5 together. While so connected, the relay 14 and it's associated contacts 10 and 11 remain closed and also the light emitting diode 12 is unlit. if 2 is disconnected from 3, or 4 is disconnected rom 5! or if the wire attached between 2 and is connected to the wore attached between 4 and 5 then, after an approximate half second time delay (a British Standards requirement) caused by the resistor and capacitor 13, the rela contacts 1 and 11 will open and the light emitting diode 12 will light.Gates 15 and 16 will cause this situation to stay latched until a deliberate resetting action is carried out.

The preceding paragraph explains how an alarm condition may be caused when the relay 14 changes state, but bearing in mind that the fault cannot cause an alarm unless it lasts longer than the delay period provided by 13, the light emitting diode 12 will however light instantly because it is connected to ' the output of gate 15 where no appreciable delay exists. For this reason the detection device, examples of which are shown in Figs 2 and 3. may be deliberately vibrated for test purposes, whereupon any short duration fault will be indicated by the flashing of the light emitting diode 12 during the period of time that the fault is is present.

Whilst the invention is intended to provide localised indication as outlined above, it may also be fitted so as to break large detection zones into several smaller zones or fitted at or near the master control unit to act as extra zone indicators additional to those provided by the control unit, or used as a temporary fault tracer.

Claims (6)

CLRIMS

1. R locally sited intruder alarm signal and fault indicator unit comprising electrically operated circuitry contained within a compact box, with provision for a means of connecting to external intruder alarm detection devices, the unit having an ability to recognise fault and alarm conditions arising in those external intruder alarm detection devices to which it is attached, together with a means of indicating this by a visible light being part of the unit and a means of relaying information of such faults and alarms to the main intruder alarm system control equipment.

2. locally sited intruder alarm signal and fault indicator as claimed in Claim 1 wherein the box containing the electrical components may be similar in shape, size and appearance as a standard oblong junction bo commonly used within the intruder alarm industry.

A R locally sited intruder alarm signal and fault indicator as claimed in Claim 1 or Claim 2 wherein the unit may be sited on or close to intruder alarm detection device in place of a standard oblong junction box, so as to form part of the intruder alarm detection device.

4. n locally sited intruder alarm signal and fault indicator as claimed in Claim 1 or Claim n. wherein the unit can convert an intruder alarm detection device which has no independent means of giving a localised visible indication as to its fault or alarm condition, into a detection device that can give independent indication of such condition.

5. R locally sited intruder alarm signal and fault indicator as claimed in Claim 1 or Claim 4 wherein the unit has the ability to be used for the testing for intermittent faults within the intruder alarm detection device which is connected to it, by indication from the light forming part of the unit.

6. n locally sited intruder alarm signal and fault indicator substantially as described herein with reference to Figures 1-3 of the accompanying drawing, with Figure 1 being any other circuit arrangement capable of achieving the same results.