GB2211008A - Intruder alarm device - Google Patents

Abstract

The device is devised to give warning to an occupant of a room or building that an intruder is attempting to gain access and comprises a base 3, 4 which is adapted to engage both a door or window 19 on the one hand and an adjacent fixed surface 20 on the other, to impede opening of the door or window, a pressure-sensitive detector 16, 17 mounted upon the base to detect opening pressure on the door, and an alarm is operable in response to pressure detected by the detector. In Fig. 2 (not shown), the base (30) embraces the lower edge of a door or window and has a rigid arm (33) pivoted thereto for engagement with the adjacent fixed surface (35) when the door or window is closed to resist or prevent opening of the door or window. By use of the device, a potential intruder is impeded and in addition the occupant is warned by the alarm. <IMAGE>

Description

INTRUDER ALARM DEVICE The present invention is an intruder alarm device, devised to give warning to an occupant of a room or building that an intruder is attempting to gain access.

Security considerations have experienced a massive increase in attention in recent years and a wide range of security devices have been developed for both ccamcial and domestic premises.

The security-conscious householder may spend substantial amounts of money on fitting his hcme with expensive equipment intended to deter or detect an intending intruder. However the cost of installing such equipment is a deterrent to many householders, who may recognise the value of a security alarm but are reluctant to incur the associated expense of having one installed. A significant part of the cost is that of the skilled labour entailed in the actual fitting of the equipment in place.

It is an object of the invention to provide a simple, and therefore potentially much cheaper, intruder alarm device which does not require skilled installation.

The intruder alarm device according to the present invention comprises a base, adapted to engage both a door or window on the one hand and an adjacent fixed surface an the other so as to impede opening of the door or window, a pressure-sensitive detector itunted upon said base in a position to detect opening pressure being applied to said door or window, and an alarm, electrically connected to operate in response to pressure detected by said detector.

The alarm device is suitable for use either upon a door, in which case it may engage both the door and also the floor adjacent to the door, or upon a window, in which case it may engage the window and the adjacent window frame or sill. To avoid undue repetition, the device will hereinafter be described as applied to a door, it being understood, however, that the device may be used, suitably rrodified where appropriate, as an alarm for a window.

In use, the alarm device is placed behind a door, with the base engaging the door and the adjacent floor surface. If an intruder attempts to open the door, the base resists the opening while at the same time pressure of the door against the detector causes the alarm to give warning of the attempted intrusion.

Two forms of base for the device are particularly preferred, namely a wedge-shaped base which may be inserted between the lower edge of the door and the floor, and a base having a movable member adapted to be moved into a floor-engaging position when the device is placed in position. The wedge-shaped form of the device is preferably resilient.

Thus the base may comprise a wedge-shaped piece of a resilient material. Alternatively it may, as in one embodiment described and illustrated by way of example below, comprise a wedge constructed upon the basis of a piece of resilient material of generally uniform thickness associated with an inclined surface of a non-resilient material. The resilient material may be a natural or synthetic ruler or a foamed synthetic polymeric material of suitable strength. The e non-resilient material may be a metal or a rigid synthetic polymeric mateiaal.

then the base is of the wedge-shaped form, it may be designed to allow the angle of the wedge to be adjusted to accommodate the wide range of gaps which exists between the lower edges of doors and the floor.

In the alternative particularly preferred form referred to above, the base may be adapted to embrace the lower edge of the door, for example it may be of a squared U-shape in cross-section or may have a door-receiving channel, and the movable member may be pivoted about a horizontal pivot which allows that member to be swung from a stowed or retracted position into one in which it engages the floor.

Preferably the part of the base which engages the floor has a surface of good frictional characteristics. For example it may be made of rubber or have a rubber-coated surface.

Upon the base, or within an assembly mounted upon the base, a pressure-sensitive detector is mounted so as to detect when an attempt is made to push the door open. Thus it is preferably so orientated as to be particularly responsive to pressure applied in a generally horizontal direction. The detector may be any desired detector of the pressure-sensitire type, for example a simple one wherein pressure directly closes a pair of contacts or a more sensitive detector incorporating a piezoelectric sensor.In a preferred, robust version of the present invention, the detector comprises a button, bar or pad bearing directly upon a contact strip of resilient metal, which under pressure applied to the door causes that contact to electrically engage a second contact and thereby close an electrical alarm circuit.

The alarm is preferably an audible alarm, since such an alarm best combines a warning to the occupant with a deterrent to the potential intruder. However, if desired, a visual alarm such as a flashing light may be employed in appropriate circumstances, for exampXe where the occupant has impaired hearing, or both visual and audible alarms may be provided. In general, an alarm which operates only while pressure continues to be applied to the detector is sufficient, although if desired the alarm may be designed to operate continuously once triggered until it is switched off or otherwise disconnected.

Power to operate the alarm is preferably provided by a battery also mounted upon the base, in order that the alarm device may be completely self-contained and wholly portable.

Such an arrangement also ensures that the device remains fully operable in the event of a power failure or an illicit severing of the power supply. Ndnetheless, the device may be designed to receive its power fram the mains supply if desired.

The-invention will now be further described with reference to the accompanying drawings, which illustrats, by way of example, two preferred embodimEnts of the intruder alarm device according to the present invention and wherein: Fig. 1 illustrates, in vertical section, a first embodiment of the device; and Fig. 2 illustrates, also in vertical section, a second embodiment of the device.

The device illustrated in Fig. I comprises a housing 3, which is of lightweight rigid synthetic polymeric material but may alternatively be of tin-plate or other metal, mounted upon a thin, resilient rectangular base 4 of non-slip synthetic rubber.

Pivoted at 5 at the forward end of the base is a plate 6, which is urged upwardly, in an anticlockwise direction about the pivot 5 as illustrated, by a helical compression spring 7. The upper limit of pivoting of the plate 6 is set by the position of a pin (not shown) extending through a selected hole 8 of a vertical series of holes in a flat column 9 (or a pair of such columns) projecting upwardly fran the side(s) of the base.

Within a conFeltment 10 of the housing 3, a battery 1 is retained between resilient contacts 12, 13. The contact 12 is electrically connected by a wire 14 to an audible alarm 15 of approximately 80 Dba volume, while contact 13 is linked to a sprung upstanding contact 16, the upper end of which terminates close to, but normally spaced from, a contact point on the body of the alarm 15. On the front face of the housing 3 is mounted a button 17, retained in place by the sprung contact 16.

In use, the illustrated intruder alarm device is placed with its wedge-shaped forveuyl end located in the space between the Fizz lower edge 18 of a door 19, for examçle, and the adjacent floor 20. When the angle of inclination of the plate 6 has been adjusted to correspond to the height of that space, a pin is removably inserted in the appropriate hole 8. If now an intending intruder attempts to open the door, the resilient wedge comprising the inclined plate 6 and base 4 provides a considerable resistance to the door opening.At the same time, pressure on the front of the door causes the door to press the button 17, which in turn presses the sprung contact 16 to engage the corresponding contact point on the casing of the alarm 15 and thereby close the electrical circuit fran the battery 11 to the alarm. The consequential sounding of the alarm warns the occupier that an intruder is attempting to open the door, while also deterring the intruder fran further attempts to gain entry.

The second preferred embodiment of the invention, which is illustrated in Fig. 2 of the accompanying drawings, comprises a member 30 having a generally squared U-shaped cross-section and designed to loosely embrace the lother edge of a door 31.

The member 30 is open at its ends and may therefore readily be slid endwise on to the door when the latter is in an open position.

Pivoted on a pivot 32 on the rear wall of the member 30 is a rigid arm 33, which carries a rubber cap 34 at its free end.

When the door is in its closed position, the arm 33 may be swung fran a generaLly upward orientation - (not shown) into the illustrated position in which the cap 34 abuts the floor 35 at an acute angle and acts to resist or prevent opening of the door.

In the rear wall of the member 30 is a pssh-button 36, which is operable to press a sprung contact 37 to compete the circuit.of an alarm 38, powered, as in the device of Fig. 1, by a dry-cell battery 39. Thus pressure on the door 31 by a potential intruder presses the button 36 and sounds the alarm.

The illustrated devices are suitable for constructing in a very compact form, making them highly portable between different places of use. For example, the device illustrated in Fig. 1 may be made with a maximum dimension of no morse than 7.5 an.

It could readily be carried in the pocket and used, say, to secure a hotel bedroom. While it has been described in the context of protecting a door it can, in an appropriate situation and possibly after modification, be used to protect a window.

Claims (16)

1. An intruSer alarm device comprising a base, adapted to engage both a door or window on the one hand and an adjacent fixed surface on the other so as to impede opening of the door or window, a pressute-sensitive detector mounted upon said base in a position to detect opening pressure being applied to said door or window, and an alarm, electrically connected to operate in response to pressure detected by said detector.

2. An intruder alarm device as claimed in claim 1, wherein the base is wedge-shaped.

3. An intruder alarm device as claimed in claim 2, wherein the base comprises a piece of resilient material of generally uniform thickness associated with an inclined surface of a non-resilient material.

4. An intruder alarm device as claimed in claim 3, wherein said resilient material is a natural or synthetic rubber or a foamed synthetic polymeric material and the non-resilient material is a metal or a rigid synthetic polymeric material.

5. An intrUder alarm device as claimed in any of claims 2 to 4, wherein the enclosed angle of the wedge is adjustable.

6. An intruder alarm device as claimed in claim 1, wherein the base has a movable member adapted to be moved into a position in which it engages said adjacent fixed surface.

7. An intruder alarm device as claimed in claim 2, wherein the movable nraber is pivoted about a horizontal pivot.

8. An intruder alarm device as claimed in claim 6 or 7, wherein the base is adapted to embrace the lower edge of said door or window.

9. An intruder alarm device as claimed in any of the preceding claims, wherein the part of the base which is adapted to engage the adjacent fixed surface is of rubber or has a ruhber-coated surface.

10. An intruder alarm device as claimed in any of the preceding claims, wherein the pressure-sensitive detector is orientated to respond to pressure applied in a generally horizontal direction.

11. An intruder alarm device as claimed in any of the preceding claims, wherein the pressure-sensitive detector incorporates a piezoelectric sensor.

12. An intruder alarm device as claimed in any of claims 1 to 10, wherein the pressure-sensitive detector includes a pair of contacts closable by pressure.

13. An intruder alarm device as claimed in any of the preced m g claims, wherein the alarm is an audible alarm.

14. An intruder alarm device as claimed in any of the preceding claims, including a battery to opera the alarm.

15. An intruder alarm device substantially as hereinbefore described with reference to, and as illustrated in, Fig. 1 of the accompanying drawings.

16. An intruder alarm device substantially as hereinbefore described with reference to, and as illustrated in, Fig. 2 of the acoompanying drawings.