WO1999019850A1

WO1999019850A1 - Alarm system

Info

Publication number: WO1999019850A1
Application number: PCT/AP1998/000003
Authority: WO
Inventors: Llewellyn Roland Green
Original assignee: Chengeta, Cuthbert
Priority date: 1997-10-09
Filing date: 1998-10-09
Publication date: 1999-04-22
Also published as: AU9423498A; WO1999019850A9

Abstract

An alarm system is provided for protecting movable articles and even motor vehicles and components of such a system. The system includes a transmitter unit having a housing adapted to be positioned between an article to be protected and a support surface therefor and switch means for closing a circuit to a transmitter forming part of the unit when the article is lifted off the unit. The transmitter transmits a signal to a remote receiver which activates an alarm. The invention also provides a self-contained unit including an alarm and thus obviating the transmitter and receiver.

Description

ALARM SYSTEM

FIELD OF THE INVENTION

This invention relates to an alarm system for detecting the unauthorised movement of a movable object and its components.

BACKGROUND TO THE INVENTION

With the increase of theft applicant considers it to be desirable to provide a relatively cheap portable alarm system for detecting the unauthorised removal of movable goods. It is also considered desirable that the system be not readily perceivable and/or accessible so that it cannot easily be disarmed by a would-be thief.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided an alarm system for detecting unauthorised movement of a movable object, the system comprising a transmitter unit having portable housing means adapted to be positionable between a movable object and a support surface or fixture against which the movable object rests, the housing means being dimensioned relative to the movable object so that when in position it is substantially obscured from view by said movable object; switch means located on the housing which are activated when the object is moved; transmitter means located in the housing and adapted to transmit a signal when the switch means are activated; a remote receiver unit for receiving the signal from the transmitter means; and alarm means adapted to be activated by the remote receiving means.

Preferably the housing means is locatable on a support surface beneath a stationary movable object.

Preferably the switch means is a pressure responsive switch. Conveniently the o switch means is a normally closed micro-switch which is held in an open position by the weight of the object and is activated into a closed position when the object is moved. Typically, the micro-switch is a push-button switch which is biased by a spring.

Preferably the receiver means is located in a portable receiver housing.

5 Conveniently, the alarm means is also located within the same portable receiver housing.

Typically, the alarm system, is aimed at the prevention of theft of a motor vehicle, the housing being substantially hidden from view when placed on a support surface beneath a wheel of the vehicle, wherein the switch means co-operativeiy o engages with the wheel and is activated when the wheel is moved.

Advantageously, the housing means defines an enclosed column which is substantially water and dust proof.

According to a second aspect of the invention there is provided a portable transmitter unit for use in an alarm system as defined above the device 5 comprising a housing adapted to be positioned between a movable object and a support surface or fixture against which a movable object rests, the housing being dimensioned relative to the movable object so that when in position it is substantially obscured from view by the resting movable object; switch means adapted to be activated when the object is moved; and transmitter means o adapted to transmit a signal when the switch means are activated. Further, the invention also provides an alarm device for detecting unauthorised movement of a movable object, the device comprising a portable housing means which can be positioned between the movable object and a support surface or fixture against which the movable object rests, the housing means being dimensioned relative to the movable object so that when in position it is substantially obscured from view by the resting movable object; switch means associated with the housing and adapted to be activated when the object is moved; and alarm means associated with the housing for generating an audible or visible alarm on activation of the switch means following movement of the object.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

FIG.1 is a pictorial view of a transmitter unit of an alarm system of the invention positioned beneath a wheel of a motor vehicle (not shown);

FIG.2 is a cross-sectional side view of the transmitter unit of the alarm system;

FIG.3 is a top plan view thereof; and

FIG.4 is a schematic block diagram of the alarm system of this embodiment of the invention.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Referring to Figure 1 , an alarm system according to the invention comprises a transmitter device having a portable housing (10) which is beatable on a support surface (12) beneath a wheel (14) of a motor vehicle (not shown). The housing (10) is obscured from view in this position and cannot readily be accessed without moving the wheel, and is accordingly shown in dotted outline.

Referring now to Figures 2 and 3, the housing (10) of the transmitter comprises a round dome-shaped plastic moulded housing portion (16) defining an enclosed volume, and which has a structural integrity sufficient to withstand that portion of the weight of a motor vehicle exerted on the device in use. The housing portion (16) is joined to a round steel backing plate (18) by means of a screw (20) thus completing the housing (10) and defining a substantially dust and waterproof enclosure in which the components of the device, described in more detail below, are located.

Positioned on the operatively upper surface (22) of the housing portion is a push-button switch (24). The switch (24) is held in an "open" position (pressed toward the backing plate) either by a pivot clip (26) or a clip (29) which engages with apertures (31) in the operatively upper surface (22) of the housing portion when the transmitter is not in use, or by the weight of the wheel (14) when the o transmitter is in use, in position on a support surface (12) beneath the wheel (14).

The switch further comprises a spring (27) which biases the switch into a "closed" position when the clip (26) or (29) is disengaged or the weight of the vehicle is removed from the transmitter.

The transmitter further comprises a power source in the form of a 12 volt 5 miniature alkaline battery (28) which is connected to a transmitter circuit (30) located within the housing. When the switch (24) is in the "open" position the circuit is open and there is no drain on the battery. When the switch is in the "closed" position the circuit is closed and the transmitter is energised by the battery, transmitting a signal. The circuit is further provided with a selector for o selecting the frequency of the transmitted signal.

A rubber diaphragm (32) seals the switch (24) making the transmitter water and dust resistant, as described above.

Referring now to Figure 4, the alarm system comprises a transmitter circuit (34) and a receiver circuit (36). The transmitter circuit is housed in housing shown in 5 Figures 1 to 3 and comprises a power supply, an activating switch (24) and a transmitter.

The receiver circuit is also housed within a portable hosing and comprises audible alarm means (38) located within the housing, a toggle switch (40) for switching the receiver on and off and for resetting the system, a relay switch (42), auxiliary contacts (44), and internal power supply and a jack (46) for connecting 0 the receiver to an external power supply. In use, the toggle switch (40) is closed to arm the system. The system is activated by a signal from the transmitter which causes the relay switch (42) to close, completing the circuit to the alarm (38), thereby sounding the internal alarm. The auxiliary contacts (44) may be connected to a separate alarm system so that the portable receiver also activates an auxiliary alarm. The alarm will sound until it is reset by switching the toggle switch into the off position. A test switch (48) is also provided for testing the internal alarm (38). In use the rest switch (48) will remain open.

The range of transmitter from the receiver will depend on the type and size of transmitter used. In the embodiment of the invention described, with the constraints of the size of the housing and cost of the equipment, the maximum range is about 200 meters.

In the embodiment described above, the alarm system is primarily intended for use in preventing the theft of a vehicle such as a motor car or a trailer, but could of course be used in other applications where the unauthorised removal of an object is required to be detected.

In a first example, for the purpose of protecting a trailer, the auxiliary contacts of the alarm system of the invention could be connected to the alarm system of a motor car. When the owner is on holiday and wishes to park the motor car and trailer for the night, the transmitter would be placed beneath a wheel of the trailer. Any movement of the trailer will cause the transmitter to set off the alarm in the motor vehicle, alerting the owner or passers-by to the unauthorised movement of the trailer.

In a second example, for the purpose of preventing the theft of a motor car, the auxiliary contacts of the alarm system of the invention could be connected to the alarm system of a house. When the owner or guest (who possibly do not have an alarm in their motor vehicle) park their motor car outside the house, the transmitter can be placed beneath a wheel of the motor car. Any unauthorised movement of the motor car would then activate the house alarm, notifying the owner of the unauthorised movement of the car.

This system will also be very useful for protecting movable goods in a warehouse, particularly where other goods are continually moved in and out of the warehouse. The transmitter can be placed beneath goods which are not to be moved and any attempted removal of the goods would set off an alarm. The particular usefulness of this is that the transmitter can be moved to wherever goods in need of protection have been placed. The strength of the transmitter housing will be dictated by the weight of the movable object which is to be protected. For example, the housing for a transmitter for detecting the movement of a motor vehicle will be far stronger than the housing of a transmitter for detecting the movement of goods such as a sack of mealie, for example. However, it is the intention of the inventor that there be a universal housing which is strong enough to be placed beneath the wheel of a heavy vehicle and is also small enough to be placed beneath a much lighter and smaller object such as a sack of mealies.

The housing of the receiver is also compact enough to allow it to be transported with ease. The receiver has its own power supply or can be connected to an external power supply. The housing for the receiver will therefore be capable of being installed in a motor vehicle or it will be just as easy to place the receiver on the bedside table of a farmer who wants to be alerted of movement of any goods within his barn.

In a more simple version of the invention the "transmitter" device could (in a non-transmitting application) comprise simply the housing portion (16), switch means (24), and alarm generating means within the housing for signalling audibly or visibly the removal of an object underneath which the "transmitter" rests.

Another particular advantage of the alarm system is that the transmitter is hidden from view and is inaccessible when it is in place beneath a movable object. In the first place, this makes it difficult, if not impossible, to disarm the transmitter and in the second place, a would-be thief would not know that the goods are protected and it is possible to catch the would-be thief red-handed when he/she moves the goods in an attempt to steal them.

Another advantage of the system is that it is relatively cheap and can stand alone or be connected to a more sophisticated auxiliary alarm system.

Claims

1. An alarm system for detecting unauthorised movement of a movable object, the system including a transmitter unit having portable housing means adapted to be positionable between a movable object and a support surface or fixture against which the movable object rests, the housing means being dimensioned relative to the movable object so that when in position it is substantially obscured from view by said movable object; switch means located on the housing which are activated when the object is moved; transmitter means located in the housing and adapted to transmit a signal when the switch means are activated; a remote receiver unit for o receiving the signal from the transmitter means; and alarm mean adapted to be activated by the remote receiving means.

2. An alarm system as claimed in claim 1 in which the switch is a pressure responsive switch adapted to be held in an open condition by the weight of an object therein and biased to a closed position.

5 3. An alarm system as claimed in claim 2 in which the switch is a normally closed micro-switch.

4. An alarm system as claimed in any one of the preceding claims in which the receiver and alarm means are located in the same portable housing.

5. An alarm system substantially as herein described and exemplified with 0 reference to the accompanying drawings.

6. A portable transmitter unit for use in an alarm system claimed in any one of claims 1 to 5, the device comprising a housing adapted to be positioned between a movable object and a support surface or fixture against which a movable object rests, the housing being dimensioned relative to the 5 movable object so that when in position it is substantially obscured from view by the resting movable object; switch means adapted to be activated when the object is moved; and transmitter means adapted to transmit a signal when the switch means are activated.

7. An alarm device for detecting unauthorised movement of a movable object, 0 the device comprising a portable housing means which can be positioned between the movable object and a support surface or fixture against which the movable object rests, the housing means being dimensioned relative to the movable object so that when in position it is substantially obscured from view by the resting movable object; switch means associated with the housing and adapted to be activated when the object is moved; and alarm means associated with the housing for generating an audible or visible alarm on activation of the switch means following movement of the object.