FR2482338A1 - Antitheft device for attache case - uses receiver with alarm triggered by loss of signal from transmitter within case - Google Patents

Abstract

The device uses a low power transmitter supplied from a battery placed within the case, cooperating with a receiver carried by the owner and having an alarm controlled by a threshold stage. The alarm comprises a light source and/or an audible alarm and is similarly supplied from an incorporated battery. Pref. the transmitter and receiver each have similar plastics casings with an external switch for switching the device On and Off and an antenna extending along one face of the casing. Each uses miniaturised electronic components and operates at a specific transmission frequency within a legally designated frequency band. The device does not require any modification of the case and provides an immediate alarm if the case is removed or left behind.

Description

The subject of the present invention is a security device intended in particular, but not exclusively, for the protection of personal objects such as attachments or cases capable of containing important documents or objects of high value.

We hardly know in the field where the present invention applies that devices constituted by a chain, one end of which is connected to the wrist of the wearer, and the other end of which is connected to the briefcase, the separation of the case and chain that can produce an alarm.

This known device does not allow the wearer to move away from the case, and presents dangers of accidental triggering of the alarm.

 The subject of the present invention is a security device which is more flexible to use and which, in addition to the security problem mentioned above, makes it possible to avoid forgetting certain objects.

According to the present invention, the security device, in particular for personal objects, is characterized in that it comprises a transmitter of radio waves or ultrasound waves, of relatively low power, emitting on short wavelength and a receiver, said receiver being provided with a device controlling visual, audible or other alarm means.

 Preferably, the object to be protected is provided with a transmitting device, while the receiver and its alarm system are carried by the owner of the object.

 The alarm means can consist, for example, of a buzzer and / or a light emitter preferably with impulse operation, in order to avoid too rapid discharge of the electric batteries used to power the assembly.

 Other characteristics and advantages of the invention will appear during the description which follows, of a particular embodiment, given solely by way of nonlimiting example, with reference to the single figure which represents an emitter and a receiver.

 The transmitter A comprises in a box 1, for example made of plastic, an electronic circuit 2 forming a transmitter and capable of continuously transmitting either a sinusoidal signal or pulse trains, preferably at high frequency, so as to that the signal emitted is directional. The transmitter circuit 2 is powered by an electric, rechargeable battery 3 or by commercial batteries. A switch 4 enables the emission to be triggered.

 We find on the receiver B, a control switch 5, a receiver circuit 6 comprising a threshold stage, a supply battery 7, and alarm means 8 controlled by the threshold stage of the receiver 6.

 As for the transmitter, the receiver is preferably contained in a box 9 of plastic material for example, the antennas necessary for transmission and for reception (not shown) extend over the faces of the boxes.

 The realization of the present invention has of course been permitted only by the appearance of miniaturized electronic components.

 The operation of the device is as follows: the transmitter and the receiver being powered by action on switches 4 and 5, the carrier of the case moves with it, and nothing happens since the signal received by the receiver is d '' a level sufficient not to trigger the alarm means.

 In the case of an object that one wishes not to lose or forget, the transmitter is placed in the object and its owner carries the receiver, the alarm functioning as soon as the owner moves away from a few meters from the 'object.

 In the case of anti-theft protection of the object, for example a briefcase, the transmitter is carried by the owner, and the briefcase provided with the receiver and its alarm system.

 If the case is stolen by a thief, for example, said case and consequently the receiver move away from the transmitter. I1 results in a decrease in the level of the signal received by the receiver and from the moment when the case is distant by a few meters in a straight line and without obstacle, the level of the signal received passes below the threshold predetermined by the threshold stage , and this triggers the light or optical alarm means, or possibly the explosion of an explosive charge.

 Preferably, the transmitter and the receiver are calibrated on a defined frequency, in accordance with the legislation, chosen in the decametric bands.

 It goes without saying that modifications can be made to the embodiments which have just been described, in particular by substitution of equivalent technical means, without departing from the scope of the present invention.

Claims (3)

 1 - Security device in particular for personal items, characterized in that it comprises a relatively low power transmitter and a receiver, said receiver being provided with a threshold stage controlling alarm means.  2 - Device according to claim 1, characterized in that the aforementioned alarm means consist of a sound and / or light source. 3 - Device according to one of claims 1 or 2, characterized in that the transmitter and the receiver work in HF.