GB2324636A - Intruder deterrent device - Google Patents

Abstract

An intruder deterrent device comprises detector means (10, 11) for detecting the presence of an intruder in a predetermined space around the device, a smoke generator (4) responsive to detection of the intruder by the detector means for generating sufficient smoke to fill the space, signalling means (8, 12) for generating a warning signal to indicate detection of an intruder, and an energy source (5) for providing energy for operation of the device.

Description

INTRUDER DETERRENT DEVICE Field of the Invention This invention relates to an intruder deterrent device, for example for use in enclosed spaces.

Background to the Invention Throughout the country there are buildings which are temporarily or permanently unoccupied and which contain property which may be attractive to thieves. The building may be, for example, an empty house, an agricultural store or a golf club greenkeeper's shed. For such buildings the installation of a permanent alarm system may be impractical, because of the cost of installation and in some circumstances the absence of a mains power supply, and may also be ineffective, since remoteness may mean that even if the police are alerted by the alarm sounding, the thieves will have departed with the property from the buildings before the police arrive. While permanent protection may be required for some buildings, for others the requirement may be for temporary protection for anything from a few days to a few months.

Smoke generation systems are known for use in buildings containing high-value items, for example warehouses or offices, but are used with permanent alarm systems.

Such systems rapidly fill the room in which they are installed with a dense smoke, which although harmless may be irritant, making it impossible for the intruders to see within the room and driving the intruders out before they can do any damage or steal anything. The smoke can be designed to persist for a sufficient time to permit the police or other security officers summoned by the alarm system to arrive at the building, but will not damage the room or its contents. Smoke may be generated by pyrotechnic devices or by thermal fogging systems which vaporise a liquid to produce a fog or aerosol of liquid droplets.

Summary of the Invention According to the invention, there is provided an intruder deterrent device comprising detector means for detecting the presence of an intruder in a predetermined space around the device, a smoke generator responsive to detection of the intruder by the detector means for generating sufficient smoke to fill the space, signalling means for generating a warning signal to indicate detection of an intruder, and an energy source for providing energy for operation of the device.

Preferably, the signalling means comprises a radio transmitter. The radio transmitter sends a signal to a remote monitoring station following the receipt of an activation signal from the detection system. The radio transmitter may use an existing radio network by signalling the activation by means of a sub-audible tone, or else may use an independent network dedicated to the signalling of illegal entry. A further possibility would be the use of cellular telephone technology automatically to dial up a monitoring station when activated.

Additionally or alternatively, the signalling device may comprise an audible alarm sounder. This may simply produce an alarm tone or tones, but it may alternatively pro duce a recorded voice message.

The energy source is suitably a battery, for example a high capacity charge able battery.

The movement sensor may be a passive infra red device or a dual technology type of detector (using two different sensors, such as passive infra red and microwave sensors, to reduce the risk of false alarms attributable to one particular type of sensor, as the likelihood of errors arising with both types at the same time is very small), but it may also be a simpler type of detector, for example a pressure switch placed on the floor near to the entrance to the building, for example. The switch may be connected to the device by means of wires, but wireless connections may also be employed. The pressure switch may be a release switch which can be placed beneath an item of property within the room to be protected, causing actuation of the alarm and smoke when the intruder attempts to remove the item by lifting it.

A similar switch may be incorporated in the device itself, to prevent any unauthorised attempt to remove it from the room.

The smoke generator may be a pyrotechnic device in which a pyrotechnic smoke-generating charge is ignited by an electric igniter in response to detection of an intruder. Alternatively, the smoke generator may be a thermal fogging device. The smoke will be selected so as to be dense within the space, but harm less, although it may be chosen to have irritant properties so as to encourage the intruder to leave the room as soon as possible. Examples of chemicals used in the production of security smokes are terephthalic acid and cinnamic acid, the latter of these producing an unpleasant irritant smoke.

The device is preferably presented as a selftontained portable unit which can be placed within the building to be protected and activated (with a delay to permit the operator to leave before the device is armed).

The device of the invention provides a simple costeffective way of providing temporary protection to unoccupied buildings or longer-term protection to buildings for which conventional built-in alarm/deterrent systems cannot be provided, for example because of their remoteness, or lack of mains electric power.

Brief Description of the Drawing The drawing illustrates diagrammatically a device according to an exemplary embodiment of the invention.

Detailed Description of the Illustrated Embodiment The device comprises a casing 1 containing two compartments 2 and 3. The first compartment 2 houses the electronic components and the battery, while the second compartment 3 houses the smoke generator 4. The battery 5, which may be a rechargeable battery or primary cells, supplies power via connecting leads 6 to a central control unit 7 and to a radio transmitter 8. The central control unit 7 incorporates a short range radio receiver with an antenna 9 within the casing 1, the receiver receiving warning transmissions from a remote passive infra red detector/transmitter 10 and from a remote pressure switch/transmitter device 11. The central control unit is linked to the radio transmitter 8, a loudspeaker 12 and the smoke generator 4 so as to be able to send electrical signals to each of these selectively. A key lock switch or keypad (not shown) is mounted on the casing and linked to the central control unit 7 to permit activation and deactivation of the device by the operator. In the case of deactivation, the central control unit 7 will typically be arranged to provide a delay between detection of an intruder and operation of the alarm and smoke functions to permit the operator to enter the room and operate the key lock switch or the keypad to switch off the de vice. Alternatively, a remote handheld transmitter may be used to activate and deactivate the device from outside the room.

Although the passive infra red detector 10 is shown as being separate from the device, and therefore positionable at another location within the room for optimum intruder detection, it will be appreciated that the detector 10 could be integrated within or mounted permanently or detachably on the casing 1, the device then being positioned in the room so that an entry to the room by an intruder will be detected. In this case, the detector 10 will be connected to the central control unit 7 by wires.

When the detector 10 detects the presence of an intruder (or the pressure switch 11 is activated, for example by an attempt to lift an item of property within the room placed on it), a signal is sent to the central control unit. After a preset delay period (if remote activation and deactivation is not provided for), the central control unit 7 sends a signal to activate the transmitter 8 to signal to a remote base station a warning signal to alert the police or a security patrol. At the same time an audible alarm is generated via the loudspeaker 12 and the smoke generator 4 is triggered, causing a rapid release of a dense obscuring smoke 1 3 into the room. The smoke generator is selected so as to be able to fill the room completely with smoke in a very short period of time, for example 30 seconds, rendering it impossible for the intruder to see the items of property in the room which are to be protected, and probably engendering in the intruder a state of panic, causing the intruder to leave as quickly as possible, emptyhanded. As mentioned hereinbefore, the smoke can be of an irritant composition, for example cinnamic acid, to ensure that the departure of the intruder from the room is as rapid as possible.

To reset the device for further use after activation, it is merely necessary to install another pyrotechnic smoke generator (or recharge the thermal device with a sup ply of liquid) and ensure that the battery is fully charged. The device is readily transportable to another location when no longer needed at the first location. As is known with conventional smoke generating devices, the smoke clears after about 30 minutes, leaving only a relatively minor deposit of dust on the contents of the room, and perhaps a residual odour which can be cleared fairly easily. Thus, no long-term adverse effects arise from the use of the device in accordance with the invention.

Claims (11)

1. An intruder deterrent device comprising detector means for detecting the presence of an intruder in a predetermined space around the device, a smoke generator responsive to detection of the intruder by the detector means for generating sufficient smoke to fill the space, signalling means for generating a warning signal to indicate detection of an intruder, and an energy source for providing energy for operation of the device.

2. A device according to Claim 1, wherein the signalling means comprises a radio transmitter.

3. A device according to Claim 1 or 2, wherein the signalling means comprises an audible alarm.

4. A device according to Claim 1, 2 or 3, wherein the energy source comprises an electrical battery.

5. A device according to any preceding claim, wherein the detector means comprises a movement sensor.

6. A device according to Claim 5, wherein the movement sensor is a passive infra red sensor.

7. A device according to any of Claims 1 to 4, wherein the detector means comprises a pressure switch locatable at a position within the space remote from the device, means being provided to signal activation of the switch to the device.

8. A device according to Claim 7, wherein the pressure switch is linked to the device by means of wires.

9. A device according to any preceding claim, wherein the smoke generator comprises a pyrotechnic charge and means for igniting the charge in response to detection by the detector means.

10. A device according to any of Claims 1 to 8, wherein the smoke generator comprises a thermal fogging device.

11. An intruder deterrent device, substantially as described with reference to, or as shown in, the drawings.