WO1994007220A1

WO1994007220A1 - Burglar alarm

Info

Publication number: WO1994007220A1
Application number: PCT/AU1993/000478
Authority: WO
Inventors: James Alan Lear; Ivor Charles Larry
Original assignee: James Alan Lear; Ivor Charles Larry
Priority date: 1992-09-23
Filing date: 1993-09-17
Publication date: 1994-03-31

Abstract

A burglar alarm comprises a telescopic body comprising an outer tube (5) and an inner tube (4) and expandable nut locking means (6, 7, 8) to hold the two tubes in any desired degree of extension. A micro switch (S1) at one end of the body functions as a sensor reacting to applied pressure or to relaxation of same to control a battery powered, audible signal generator (B) by way of enabling circuitry (figure 2). The battery, signal generator, circuitry, and micro switch are all mounted within the body to constitute a self-contained, readily installed unit adapted to extend from a sliding door panel or window sash to an end of the slide track for same, whereby subsequent movement of the panel or sash is monitored.

Description

BURGLAR ALARM

TECHNICAL FIELD

This invention relates to burglar alarms, in particular alarms which monitor the position of a sliding door panel or window sash and are activated by movement thereof.

For descriptive convenience the term "room closure" is used hereinafter to refer to both doors and windows, and the term "sliding element" is used to refer to either the sliding sash of a window or the sliding panel of a door.

BACKGROUND ART

Hitherto such alarms have comprised reed switches, micro switches or other proximity sensors permanently associated with the room closure. The sensor responds to movement of the closure's sliding element and triggers a, usually remote, warning device by way of alarm circuitry interconnecting the sensor and the alarm device.

Such prior known arrangements have been permanent in nature, and have usually required expert installation, involving intrusive modification of the closure surround and the fabric of the building being protected, to ensure the integrity of the alarm system and to hide it from view. Thus, prior known alarms of the kind in question have been expensive, and their installation has been beyond the capability of most people. DISCLOSURE OF INVENTION

Therefore, an object of the invention is to provide a burglar alar that is adapted to monitor the position of the sliding element of a slidin room closure and which may be emplaced, or replaced, as needed t monitor any individual closure within a wide range of closure size without the need for tools or skill on the part of the person installing setting the alarm.

The invention consists in a burglar alarm for use in conjunctio with a room closure of the kind comprising a sliding element and a guid track for said element, said alarm comprising buffer means able to b removably located on said guide track, a pressure sensitive sens responsive to pressure applied to the buffer means by the slidin element, and battery powered warning means controlled by said senso said buffer means, sensor and warning means being fixedly associate with each other to form a self-contained unit.

Thus, to install a burglar alarm according to the invention so as t monitor a sliding closure providing access to a room, it is merel necessary to secure the alarm to the guide track in substantial abutme with a or the sliding element of the closure that would have to be move to enable a person to gain entry to the room to pass through th closure. An advantage of the alarm over conventional installations i that the monitored sliding element may be left in a partly open positio for ventilation without detriment, provided the alarm is positioned so th its power "ON-OFF" switch cannot be reached from outside witho moving the sliding element. In preferred embodiments the buffer means comprise a lengt adjustable, elongate body, and may be secured as aforesaid by layin the body on the track and extending it so that it reaches from th monitored sliding element along the track to an end abutment thereo Preferably such embodiments admit of two modes of operation, namely a first mode in which the warning means respond to the imposition o pressure upon the sensor and a second mode wherein the warnin means respond to the relaxation of pressure on the sensor. The firs mode is selected when the alarm is positioned so that it extends fro the sliding element to the end abutment of the track that would b contacted by the element if the room closure were fully open. Wherea the second mode is selected if the alarm is positioned so that it extend to the abutment that would be contacted by the sliding element if th closure were fully closed. In either instance the alarm would b triggered by any opening movement of the sliding element away fro the set position.

The pressure sensitive sensor may be of any known type and ma be mounted in or on that elongate body in any way enabling it to oppos end loadings thereon. However for simplicity's sake it is preferably micro switch mounted at one end of the body, or within a protectiv pliable boot covering said one end.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, an embodiment of the above describe invention is described in more detail hereinafter with reference to th accompanying drawings. Figure 1 is a partly cut away perspective view of a burglar alar according to the invention.

Figure 2 is a detail sectional view of locking means, being component of the alarm of figure 1 drawn to a larger scale.

Figure 3 is a circuit diagram of the warning means and sensor o the alarm of figure 1.

BEST MODE OF CARRYING OUT THE INVENTION

The illustrated embodiment comprises an elongate, telescopi body comprising an inner member 4 protruding from one end of, an slidable to and fro in, an outer member 5. The inner member 4 may b a rod or tube, and the outer member 5 may be a tube. The protrudin end of the inner member 4 may be finished with a button or head 1 preventing it from fully entering the bore of the outer member 5.

The inner member 4 may be pulled from the outer member 5 t any desired extent consistent with a short end portion of the inne member 4 remaining within the outer member 5. The two members ar furnished with any conventional, releasable locking means to enable th two to be fixed against telescopic movement at any selected extension.

For example, the said short end portion of the inner member may be plugged by a plug 6 with an axially projecting, tapered externally threaded stud 7 adapted to engage a resilient, moulde plastics or other expandable sleeve or nut 8 that may slide within th outer member 5 when not expanded, but which frictionally grips th outer member 5 firmly when expanded. The nut 8 may be expanded o allowed to relax by relative rotation of the two members 4 and 5 abou their common longitudinal axis. For preference that nut or sleeve i loosely trapped on the end of the inner member 4 by means, fo example, of a small head 9 on a short stem 10 protruding from the en of the stud 7 through a stem clearance hole in an end wall 11 closin the bore of the nut 8.

A removable, cylindrical cartridge 12 may be lodged within th end portion of the outer member 5 remote from the end penetrated b the inner member 4. That cartridge may house or carry all of th electric or electronic components constituting the sensor and warnin means of the alarm, including a battery B2 for energising thos components. In particular, the cartridge 12 ends in a "soft touch" micr switch S1 with its pressure sensitive element 13 projecting from one en of the cartridge 12, being an end of the cartridge which, in use, project slightly from, or is substantially flush with, the last mentioned end of th outer member 5. Alternatively the micro switch S1 , or its functiona equivalent, may be positioned within the cartridge, and a push rod or th like may extend from the switch beyond the end of the cartridge. I either event the pressure sensitive element is preferably covered by pliable end cap, boot 14 or other pliable cover on the outer member 5, which is adapted to exclude dust and the like from the cartridge and th switch mechanism, while leaving the switch free to respond to pressur on that cover.

The cartridge may also house a two pole, three position ON-OF and mode selector switch S2; a bell, a transducer and oscillator producing a tone or a noise similar to the wail of a siren, or othe audible signal generator; a timing circuit or device, that limits the time fo which the audible signal generator sounds after an initial operation an then resets the alarm for a second response if the conditions producin the first response persist or are repeated; and flashing or steady lig indicators evidencing the state of the alarm, for example a flashing lig from a light emitting diode L2 may show that the alarm is switched on.

All of the foregoing electrical components are interconnected b appropriate circuits, preferably on a printed circuit board. Basicall these components individually and the circuitry connecting them may b in accord with the corresponding components and circuits of prior a burglar alarm installations of the kind referred to at the outset, howev for the sake of completeness of description, one appropriate circuit i illustrated by figure 3 and is briefly described below.

The micro switch S1 is a normally open, self opening switch. Th is to say it is closed if pressure is applied to its pressure sensitiv element 13 so as to depress same, and reopens automatically if th pressure is relaxed.

The ON-OFF switch S2 is also a mode selector switch. When i its OFF position (the centre position as shown in figure 3) it isolates th battery B2 and the entire alarm is inactive. When switch S2 is in it upper position, corresponding to ON in a first mode of operation, th alarm is triggered if switch S1 is moved from open to closed. Wherea when switch S2 is in its lower position, corresponding to ON in a secon mode of operation, the alarm is triggered if switch S1 is moved fro closed to open.

In both of the ON modes one pole of switch S2 energises th positive rail VCC at 9 volts from battery B2. In the first ON mode switch S2 connects switch S1 directly t pin 2 (trigger) of an integrated timer circuit IC1. IC1 is set as a mon stable timer and for so long as pin 2 remains high, by virtue of it connection to VCC via pull up resistor R4, it has no output. If micr switch S1 closes then pin 2 of IC1 is earthed and IC1 then causes hig volts to appear on its output pin 3. Pin 3 remains high for predetermined time determined by the values of resistor R1 an capacitor C1.

The output from pin 3 of IC1 is applied to the reset pin 4 o integrated circuit IC2, which is set as an astable pulse generator. Tha is to say, it is self-triggering and outputs high voltage pulses from it pin 3 with time durations determined by the values of Resistors R6 an R7 and capacitor C3. Those pulses are fed to the base of NP transistor T1 to cause it to turn on during each pulse, thereby t energise the transducer B for the duration of each pulse.

The transducer B may be a unit of the kind known as a sonalert which produces a siren note that gradually rises in intensity to maximum when first energised and then gradually falls off in intensit when de-energised. Thus the effect of energising it in pulses, a described above, is to cause it to produce a varying wailing sound tha is very effective at attracting the attention of any person within earshot.

When the alarm is set with the micro switch S1 held closed, the switch S2 is placed in its second ON mode (lower position in figure 3) That being so the base of transistor T2 is earthed and presents a hig resistance between its emitter and collector. Thus trigger pin 2 of IC1 i kept high and has no output. Should micro switch S1 be allowed t open as a result of displacement of the closure's sliding element, hig voltage is applied to the base from rail VCC through resistor R2, causin T2 to turn on and earth pin 2 of IC1 , whereupon the sonalert is operate exactly as described above for the first ON mode of operation.

When the cartridge 12 is in place in the outer member 5, the Lig emitting diode L2, audible signal generator, and the operating handle switch S2 are in alignment with suitable windows or openings in th outer member 5.

In other less preferred embodiments the elect. icals may b mounted directly in the outer member rather than in a removabl cartridge.

Usually, the exemplary embodiment may simply be positioned o the guide track, extended as needed, locked against contraction an switched on, to render it operable, however a spring clip may b provided to hold it in place in relation to a vertically sliding window sas if need be or preferred.

In other embodiments, a relatively short buffer means may b used, comprising a housing for the operative alarm components and screw clamp or a laterally expandable or other frictional gripping mean to fix the housing within or to the guide track for the sliding element.

Claims

1. A burglar alarm for use in conjunction with a room closure of th kind comprising a sliding element and a guide track for said elemen said alarm comprising buffer means able to be removably located o said guide track, a pressure sensitive sensor (S1) responsive t pressure applied to the buffer means by the sliding element, and batter powered warning means (B) controlled by said sensor; said buffe means, sensor and warning means being fixedly associated with eac other to form a self-contained unit.

2. A burglar alarm according to claim 1 wherein the buffer mean comprise a length adjustable, elongate body (4,5), and may be locate as aforesaid by laying the body on the track and adjusting its length s that it reaches from the sliding element along the track to an en abutment thereof.

3. A burglar alarm according to claim 1 wherein said warning mean admit of two modes of operation, namely, a first mode in which th warning means respond to the imposition of pressure upon the senso and a second mode wherein the warning means respond to th relaxation of pressure on the sensor.

4. A burglar alarm according to claim 2 wherein said sensor is micro switch mounted at one end of the body.

5. A burglar alarm according to claim 4 wherein said micro switch i within a protective pliable boot covering said one end.

6. A burglar alarm according to claim 2 wherein said elongate bod comprises an outer tubular member (5), an inner member ( telescopically slidable in the outer member (5) and locking means t enable the two members to be fixed at any selected extension.

7. A burglar alarm according to claim 6 wherein said locking mean comprise an axially projecting, tapered, externally threaded stud ( on the inner member and an expandable nut (8) on said stud; said n being sized so that it may slide within the outer member (5) when n expanded and frictionally grip the outer member (5) when expanded.

8. A burglar alarm according to claim 7 wherein said nut is loosel trapped on said stud.

9. A burglar alarm according to claim 1 wherein said warning mean comprise an audible signal generator and operating circuit mean including a battery interconnecting said sensor and said generator.

10. A burglar alarm according to claim 9 wherein said warning mean are mounted on a separate cartridge insertable into said buffer means.