GB2095016A - Alarm system - Google Patents

Abstract

A security system has a secured zone (11) and a control zone (12) from which the secured zone can be supervised by an authorised person so that the secured zone can be left unsecured while such authorised person is within the control zone, and means automatically operative to secure the secured zone whenever the authorised person leaves the control zone. The control zone can be inside or outside the secured zone. Control may be through a personal transmitter (15) acting through a loop (13) to disable the alarm system. <IMAGE>

Description

SPECIFICATION Alarm systems This invention relates to alarm or security systems, in particular those which differentiate between authorised and unauthorised personnel.

Security systems are known in which authorised personnel equipped with a personal transmitter can gain access to a secure room fitted with a door lock or alarm by disabling the alarm by the transmitter. If the transmitter is left permanently "on" such authorised personnel may come and go freely, while access is denied to all other, without such authorised personnel having to worry about locking and unlocking the door.

Such systems have certain limitations. For example, the room is not necessarily secure unless all entrances (including windows) are independently secured - if the presence of an authorised person in the vicinity of a secured door disabled the entire alarm system, an intruder could meanwhile make an entry through another door or a window. The systems might also restrict access more than is desirable -- it may be required, for example, to permit unauthorised persons free access to a room so long as an authorised person is present to supervise them, and it may even be required to permit the supervisor to come and go without having to evacuate unauthorised personnel already in the room.

The present invention provides a security system which does not suffer from these limitations.

The invention comprises a security system having a secured zone and a control zone from which such secured zone can be supervised by an authorised person so that said secured zone can be left unsecured while such authorised person is within said control zone, and means automatically operative to secure such secured zone whenever such authorised person leaves said control zone.

Generally speaking, said control zone will surround said secured zone, but need not do so, and may be entirely separate therrefrom. An example of the latter case would be for example where the control zone was a foreman's office, elevated, in a factory, the secured zone being the factory floor or a part thereof visible from the foreman's office. The secured zone might be quite a specific area, however, for example a lockable drawer in a desk or a filing cabinet - it may be desired that an authorised person has free access to such drawer and my even permit unauthorised personnel to have access to it as long as he is there to supervise them, but also that the drawer not require unlocking each time access is required.

The secured zone may be secured by a lock preventing access thereto -- as may be the case, say, in connection with a drawer as just mentioned -- or it may be secured by an alarm.

Said control means may comprise a personal transmitter, which may be battery powered, or which may be a passive device responding to signals from an external source.

A loop of wire surrounding the said control zone may act as an aerial to receive from said personal transmitter when said transmitter is inside the loop. Such a loop may, however, transmit signals to a transponder or passive device which, powered or actuated by said sign6 Is, itself transmits signals back to said loop.

The signals may be transmitted as audio frequencies. Although radio signals are generally convenient, other signals, such as infra-red or acoustic signals could also be used.

The alarm system can be of any desired type.

All that is necessary is that it be capable of being switched off-although of course, more sophisticated arrangements may be used in which the alarm system is only partially overriden. Thus, for example, an alarm system might have a number of sensing devices, acuation of any one of which would ordinarily set off the alarm. On entry of an authorised person, by means of a transmitter, into the control zone, the system might be reset to go into alarm only when any two sensing devices are actuated simultaneously.

Induction loop systems suitable for use in connection with the invention are commercially available having a range of no more than a metre or so outside the loop, even for loops having an area of 300 square metres or more. Such a loop system could be used in a restricted area such as a bank vault, or a "hot" room in a nuclear installation, say enabling authorised personnel to enter and leave freely, but ensuring that the alarm system was not disabled by their proximity to the restricted area without actually being inside where they could supervise the activities of any unauthorised personnel.

Embodiments of alarm systems according to the invention will now be described with reference to the accompanying drawings in which: Figure lisa diagrammatic illustration of one system Figure 2 is a diagrammatic illustration of another system, and Figure 3 is a diagrammatic illustration of a third system.

Figures 1 to 3 illustrate a security system having a secured zone 11 and a control zone 1 2 from which said secured zone can be supervised by an authorised person so that said secured zone 11 can be left unsecured while such authorised person is within said control zone, and means 23 automatically operative to secure such secured zone 11 whenever such authorised person leaves said control zone 1 2.

In the embodiments illustrated in Figure 1 , said control zone 12 surrounds said secure zone 11. In this case, the secured zone 11 may be a lockable drawer of a desk or a filing cabinet, and the manner of securing it may be a lock or alarm which is rendered inoperative to lock or to sound respectively whenever an authorised person is in the control zone 12, which may for this purpose comprise the room or an area of the room in which the desk or cabinet is situated.

In the embodiment illustrated in Figure 2, the control zone 12 is within the secured zone 11. It may be that the control zone 12 represents a particular vantage point from which the whole of the secured zone 11 can be supervised. Such a control zone might be a foreman's or watchman's office situated in an elevated position in regard to a factory floor.

The embodiment illustrated in Figure 3 has the control zone 12 completely outside the secured zone 11 -this situation might arise, for example, in a supermarket or a casino, where supervision is exercised from a supervisor's room outside of, but overlooking, a sales floor or a set of gaming tables or fruit machines. It might be desired, for example, to restrict access to tills, or to the coin safes of gaming machines while no authorised person was exercising supervision from the supervisor's room.

Of course, the control zone 12 could be coincident with the secured zone 1 or could be partly inside and/or partly outside the said secured zone 11.

The control zone in all illustrated embodiments is surrounded by a loop 1 3 of wire with a receiver 1 4 that detects elelctrical signals picked up by the loop 13.

An alarm system 11 a protects the secured zone 1 The system 1 a might, for example, be a simple bell actuated by a microswitch which is switched on when a drawer opens, or it might be a lock which is automatically actuated to lock the drawer when a signal is received (or stops being received) by the receiver 14.

The system 1 a might well comprise more than one detector (for example, two microswitches each guarding a separate drawer) or more than one lock. In a nuclear power installation, for example, several mechanisms such as those adapted to insert or extract fuel rods might be locked or protected by an alarm if a supervisor is outside a control region in which he can supervise the operation -- this might not involve direct oversight of the top of the reactor vessel itself, but indirect oversight through instruments including, if desired, remote controlled television cameras.

Authorised personnel can carry a transmitter 1 5, which will transmit signals to the loop 13 to be detected by the receiver 14, which then actuates, via a link 16 (which may be a wire or an optical fibre or a radio link, for example), the alarm or lock that protects the secured zone so as to activate the alarm or secure the lock when the transmitter 1 5 is taken outside the loop. It can, of course, be arranged that the alarm is deactivated or the lock is released whenever the transmitter 1 5 is brought back inside the loop 13, and this will be generally speaking the most convenient arrangement.

It can also be arranged, by having more than one transmitter 1 5 sending out different signals, for example operating at different frequencies, that the secured zone is, or can be, only rendered unsecured when two or, if desired, when three transmitters 1 5 are inside the control zone, and that the secured zone is re-secured again when any one, or if desired when any two of the transmitters are taken out of the control zone. This arrangement might be useful for bank vaults, where it is desired that the door might only be opened in the presence of two or three bank personnel, but where, when the door has been opened, it may be required that one or more of the authorised personnel not directly involved in whatever needs to be done inside the vault can go about his or her ordinary business.

The transmitters 1 5 can be provided with an on/off switch whereby an authorised person inside the control area, having rendered the secured zone unsecured, can raise an alarm simply by switching his transmitter off - in case of attack by an intruder, for example. Since, however, it may be desired to have the transmitter normally turned on to avoid false alarms through forgetting to activate the transmitter before entering a control area, the on/off switch might be made more in the nature of an emergency push button. If more than one transmitter will be in a control area at a time, of course, turning one transmitter off might not raise the alarm. It is possible, however, to have the emergency button switch the transmitter to an alarm frequency.

Where, within the secured area, more than one alarm system is operative, two or more can be connected together so that when a receiver 1 5 is inside a control area simultaneous actuation of- two more more alarms is required before an alarm is raised.

Instead of a self-powered transmitter, the loop 13 can transmit a signal to which a transmitter 1 5 responds by emitting a different signal - this can be a powered transponder, or a passive device which re-emits a different frequency on being energised by a frequency picked up from the loop.

A transponder may be switched on automatically, or may emit an audible tone or other signal to warn the authorised person that he is entering a control zone and that he should switch on his transmitter. The transmitter may switch itself off after it is taken out of the control zone or may emit another warning signal to remind the authorised person to switch it off - this can ensure that transmitters in the immediate vicinity of, but not actually inside, the control zone do not affect the alarm system.

Claims (13)

1. A security system having a secured zone and a control zone from which said secured zone can be supervised by an authorised person so that said secured zone can be left unsecured while such authorised person is within said control zone, and control means automatically operative to secure said secured zone whenever such authorised person leaves said control zone.

2. A system according to claim 1, in which said secured zone is secured by a lock preventing access thereto.

3. A system according to claim 1 and claim 2, in which said secured zone is secured by an alarm.

4. A system according to any one of claims 1 to 3, in which said secured zone is at least partially within said control zone.

5. A system according to claim 4, in which said secured zone is wholly within said control zone.

6. A system according to any one of claims 1 to 3, in which said secured zone is outside said control zone, but observable therefrom.

7. A system according to any one of claims 1 to 6, in which said control means comprise a personal transmitter.

8. A system according to claim 7, in which said transmitter is battery powered.

9. A system according to claim 7, in which said transmitter is a passive device responding to signals from an external source.

10. A system according to any one of clauses 7 to 9, in which a loop of wire surrounding the said control zone acts as an aerial to receive from said personal transmitter when said transmitter is inside the loop.

11. A system according to any one of claims 7 to 10, in which a loop of wire surrounding the said control zone acts as an aerial to transmit signals to a transponder or a passive device which, powered or actuated by said signals, itself transmits signals back to said loop.

12. A system according to anyone of claims 7 to 11, in which said personal transmitter transmits signals at audio frequencies.

13. A system substantially as hereinbefore described with reference to Figure 1 of the accompanying diagrams.

1 4. A system substantially as hereinbefore described with reference to Figure 2 of the accompanying diagrams.

1 5. A system substantially as hereinbefore described with reference to Figure 3 of the accompanying diagrams.