GB2109140A - Intruder probe - Google Patents

Abstract

Housing 10 is attached adjacent a surface whose movement is to be monitored, e.g. a pane of glass 31 in a window 30. Pivoted, spring loaded arm 12 extends from housing 10 and its tip 21 impinges on the surface 31. If said tip 21 is moved upwards or downwards more than about 0.5 to 1.0 cm e.g. by breakage of the glass 31 or opening of the window, the other end of the arm 12 within the housing 10 causes actuation of microswitch 11 which is connected to an alarm system. This may be accomplished by a block attached to the end of arm 12 pivoting about a pin so that a corner edge depresses a strip and thereby a button of microswitch 11. The probe is easy to install, not readily susceptible to false alarms and as it is visible may act as a deterrent to potential intruders. <IMAGE>

Description

SPECIFICATION Intruder probe This invention relates to an intruder probe, that is to say a probe which will detect, and trigger an alarm, when a window, door, lid or similar device to which it is applied is opened or broken.

Hitherto, intruder probes or burglar alarm systems have relied on sensitive electrical or electronic sound or vibration probes attached to, or in the case of sound detectors closely adjacent to, a relevant door, window or the like, such probes being both expensive and extremely susceptible to false alarms.

Alternatively, special adhesive tape which triggers an alarm when broken may be placed around the edge of, for example, a window or show-case lid.

The disadvantage of this tape is that it hinders cleaning of the window or lid and has to be removed and reapplied whenever the window or lid is required to be opened or thoroughly cleaned.

An object of the present invention is the provision of an inexpensive intruder probe which is easy to install, not readily susceptible to false alarms and will easily allow the window, door, lid, or similar to which it is applied to be opened or cleaned by authorised persons. It is also intended that the probe according to the present invention should be visible so that it will act as a deterrent to potential thieves or burglars.

With this object in view, the present invention provides an intruder probe comprising a housing for attachment adjacent a surface whose movement is to be monitored, said housing containing a microswitch adapted for connection to an alarm system, and a spring-loaded pivoted arm which extends out of the housing such that the free end or tip thereof impinges on said surface and movement of said free end or tip causes corresponding movement of the other end of the arm to operate the microswitch.

The housing may advantageously swivel about its attachment so that when the alarms are switched off and it is required to wash or open said surface, which maybe, for example, a door, window, lid or the like, the arm maybe swung away from the surface and no longer obstruct access thereto.

The arm is conveniently formed as an elongate metal rod with a grommet at the tip. Preferably, the arm lies substantially parallel with the surface whose movement is to be monitored and is bent at a right angle so that the tip impinges on said surface.

However, if a large surface is to be monitored by the probe, the arm preferably comprises two parts, namely an elongate rod and an elongate cross piece which is swivellably attached to the rod. The cross piece may have grommets at both tips and it may be bent to enable these tips to impinge on the surface.

The end of the arm located within the housing is conveniently attached to a transverse block of rectangular cross-section and pivot about a pin extending through said block so that movement of the tip of the arm causes operation of the microswitch by a corner edge of said block.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a first practical embodiment of the intruder probe of the invention; Figure 2 is a fragmentary perspective view illustrating the embodiment of Figure 1 in operative position in relation to a window; Figure 3 is a fragmentary perspective view illustrating a second practical embodiment of the intruder probe of the invention in operative position in relation to a window; Figure 4 is an elevation illustrating how a number of probes similar to that of Figure 1 may be arranged in relation to a conventional window; FigureS is an elevation illustrating how two probes similarto that of Figure 1 may be operatively arranged in relation to a sliding patio door;; Figure 6 is a fragmentary cross section in the direction of the arrows V in Figure 5; Figure 7 is an elevation to a smaller scale illustrating how a number of probes similar to that of Figure 1 may be operatively arranged in relation to a window comprising a single large pane of glass; and Figure 8 is a fragmentary perspective view illustrating how a number of intruder probes in accordance with the invention may be used in relation to a row of show-cases or other valuable items.

As shown in Figure 1, a first simple practical embodiment of an intruder probe of the invention comprises a housing 10, a microswitch 11 and an arm 12. The housing comprises a pair of substantially rectangular and parallel plates 13, 14, each a few centimetres in each dimension and extending perpendicularto a basal attachment flange 15. This is illustrated more clearly in Figure 2. Between the plates 13, 14 is located a microswitch 11 of known type with three electrical leads 16 for connection to an alarm system (not shown). The microswitch 11 also includes an angled strip 17, depression of which operates an underlying button 18 which, when the probe is connected to the alarm system, causes completion of an electrical circuit to set off an alarm.

The arm 12 comprises an elongate metal rod extending out of one side of the housing 10. The end of the arm 12 within the housing 10, i.e. between the plates 13, 14, is attached to the mid point of one side of a transverse block 19 of square cross-section which is located adjacent the strip 17 of the microswitch 11. The arm 12 and block 19 pivot about a pin 20 which extends, transversely of the arm 12 through the centre of said block 19. The other end of the arm 12 hereinafter called the tip 21, located outside the housing 10 has a grommet 22 of plastics material attached thereto. The entire arm 12 is spring-loaded by a spring 23 to pivot downward towards the basal flange 15 whenever the tip 21 of the arm 12 is not supported.

The installation and use of this intruder probe on a household window of average size will now be described with reference to Figure 2. The basal flange 15 of the housing 10 is screwed into a suitable position inside the window, for example half way up one side of the window frame 30. The end portion 24 of the arm 12 is bent substantially at a right angle so that the tip 21 of the arm 12 impinges on and is spring-loaded towards the surface of the pane of glass 31 while the remainder of the arm 12 lies substantially parallel to the glass surface. The leads 16 of the microswitch are then connected up to an appropriate alarm system (not shown) which is switched on.

The operation of the probe in the event of movement of the glass 31 due to opening of the window - either outwardly or inwardly or breakage of the glass 31 will readily be apparent from the foregoing description. If the tip 21 of the arm 12 is moved more than about 0.5 to 1.0cm in either direction, the block 19 at the other end of the arm 12 is pivoted so that one corner edge thereof depresses the microswitch strip 17 and button 18 and sets off the alarm.

As the intruder probe is easily visible to a potential burglar from outside the window, it is likely that the presence of the probe will deter the burglarfrom attempting to break-in.

It will be appreciated that when a large window is to be monitored for intrusion, several suitably positioned probes of the above described type should be fitted to the window so that a hole large enough to permit entry to an intruder cannot be made in a part of the window remote from any probe. An appropriate arrangement of probes for a large window consisting of several small panes of glass is shown in Figure 4. Only a single probe is required for each pane. A part of the alarm system 40 is also shown. Figure 7, on the other hand, illustrates an arrangement of probes for a large plate glass window, such as a shop window, wherein eight probes are required.

A second practical embodiment of the probe of the invention is illustrated in Figure 3. This embodiment includes an arm 12 comprising an elongate rod 32 and an elongate cross piece 33 attached by a swivel joint 34 at its mid point to the end of the rod 32 and it may be used effectively to monitor a larger surface.

Both tips 35 of the cross piece 33 have grommets 22 and are bent to impinge on the surface of the glass 31.

Many variations may be made to the above described probe. For example, the basal flange 15 of the housing 10 may be attached to the window frame 30 so as to be capable of swivelling so that, when the alarms are switched off, the arm 12 may be swung away from the pane 31 while the window is washed or opened. The housing 10 may be box-like so that the microswitch 11 is completely enclosed therein. The arm 12 may be of any suitable pliable material and may be painted white or any other colour so as to be unobtrusive when used on household windows. Also the tip or tips of the arm 12 need not be bent downwards but may be straight or bent sideways as long as they impinge on the appropriate surface.

Figure 8 illustrates a row of three probes similar to the first above-described type but having box-like housings 10 and the tips of the arms 12 bent sideways. These probes are, in the illustrated example, being used in relation to the lids of display cabinets 41, e.g. for jewelry, although they may equally well be directly applied to valuable goods such as television or Hi-fi equipment.

It will be appreciated that all of the probes as described may be adapted for use in many other situations for example household doors, sliding doors and windows fanlights; vehicle doors, windows, bonnets and boots; safe doors.

Figures 5 and 6 illustrate how the first described embodiment may be used in relation to two-part sliding patio door 42. The slidable part 43 of the door 42 is fitted with a small ridge 45 of substantially triangular cross-section so that if the door is slid open when the alarm system is switched on, the tip 21 of the probe 44 is caused to ride up over the ridge 45 and thereby trigger the microswitch and alarms.

The other probe 46 on the non-slidable part 47 of the door 42 operates in the manner described earlier in the specification.

Claims (7)

1. An intruder probe comprising a housing for attachment adjacent a surface whose movement is to be monitored, said housing containing a microswitch adapted for connection to an alarm system, and a spring-loaded pivoted arm which extends out of the housing such that the free end or tip thereof impinges on said surface and movement of said free end or tip causes corresponding movement of the other end of the arm to operate the microswitch.

2. An intruder probe as claimed in claim 1 wherein the housing is adapted for swivellable attachment adjacent the surface whose movement is to be monitored.

3. An intruder probe as claimed in claim 1 or 2 wherein the pivoted arm comprises an elongate metal rod.

4. An intruder probe as claimed in claim 3 wherein the pivoted arm further comprises an elongate cross piece which is swiveliably attached to the rod.

5. An intruder probe as claimed in any preceding claim wherein the pivoted arm is bent to enable its other end or tip to impinge on the surface whose movement is to be monitored.

6. An intruder probe as claimed in any preceding claim wherein the end of the arm located in the housing is attached to a transverse block of rectangular cross-section and the arm pivots about a pin extending through said block so that movement of the free end or tip of the arm causes actuation of the microswitch buy a corner edge of the block.

7. An intruder probe substantially as hereinbefore described with reference to the embodiments illustrated in Figures 1,2 and 4 to 8, or in Figure 3.