GB2147130A

GB2147130A - Anti-theft alarm for cassette recorders and for collections of cassettes

Info

Publication number: GB2147130A
Application number: GB08424059A
Authority: GB
Inventors: Keith Francis
Original assignee: G H L SYSTEMS Ltd
Current assignee: G H L SYSTEMS Ltd
Priority date: 1983-09-24
Filing date: 1984-09-24
Publication date: 1985-05-01
Also published as: GB8325622D0; GB2147130B; GB8424059D0

Abstract

An anti-theft alarm for insertion into a video cassette recorder is contained within a body 1 in the form of the shell of a video cassette. The alarm circuit includes a mercury tilt switch and a piezo- electric sounder which produces a continuous alarm signal when the tilt switch detects a disturbance of the cassette recorder until the circuit is de-activated. The alarm is set by removing a code key in the form of a pin from an aperture 5 in the body 1 and can thereafter only be de-activated by the insertion of the correct code key. A timing circuit prevents the alarm from sounding for a predetermined period in which the alarm may be inserted into the cassette recorder. The alarm may also be used for protecting a collection of video cassettes. <IMAGE>

Description

SPECIFICATION Anti-theft alarm for cassette recorders and for collections of cassettes This invention relates to anti-theft alarms for cassette recorders and for collections of cassettes and more particularly, but not exclusively, relates to an anti-theft alarm for a video cassette recorder.

The term cassette recorder herein refers to audio and video apparatus for recording and/ or playing back information which is stored on a magnetic tape contained within a cassette.

Accordingly, the term cassette refers to the container for the magnetic tape. Whenever it is desired to use the recording and/or playback apparatus the cassette itself is inserted into the apparatus.

There is presently a thriving market in the sale and rental of video cassette recorders and video cassettes. Associated with this market, the number of thefts of video cassette recorders and collections of video cassettes from private homes and shops has greatly increased. Consequently there is a great need for simple and effective anti-theft alarms for video cassette recorders and for collections of video cassettes.

According to the broadest aspect of the present invention there is provided an antitheft alarm for a cassette recorder, or for a cassette collection wherein the alarm is incorporated within a body in the form of a cassette or within a body in the form of a protective case for a cassette.

As an anti-theft alarm for a cassette recorder the alarm is preferably incorporated within a body in the form of a cassette. The body may be the shell of a standard cassette itself, or it may be moulded or otherwise made to conform with the size and shape of a cassette shell so that it can be inserted into the carriage of a cassette recorder.

An anti-theft alarm for a cassette collection may be incorporated either within a body in the form of a cassette or within a body in the form of a protective case for a cassette.

Preferably, within its body, the alarm comprises detecting means for detecting movement, for example tilting, of the body, and warning means for producing an audible warning signal responsive to the detecting means.

Conveniently, the alarm includes switching means for switching the alarm between an activated condition and a de-activated condition.

When the alarm is to be used it is set to its activated condition by the switching means before or after insertion either in the carriage of a cassette recorder or in a suitable space of the cassette collection depending on whether the alarm is for a cassette recorder or for a cassette collection. Subsequent disturbance of the cassette recorder or cassette collection is detected by the detecting means and an audible warning signal is produced by the warning means to indicate that the cassette recorder or cassette collection has been disturbed.

The detecting means preferably comprises one or more mercury tilt switches. One tilt switch is able to detect a tilting movement in only one sense, but this is usually sufficient to detect most disturbances of the cassette recorder or cassette collection.

The warning means preferably comprises an electrically energisable piezo-electric sounder, but it may comprise any other electrically energisable means of producing an audible warning signal, for instance an electric buzzer or bell. However, it is generally undesirable to use an electro-magnetically operated buzzer or bell because it can cause damage to parts of the cassette recorder such as, in particular, the recording and/or playback heads. Piezoelectric sounders do not suffer from this disadvantage, and furthermore they take less current and so are able to run for longer periods than conventional electric buzzers.

Preferably, once energised to produce the warning signal, the warning means is kept in its energised state and produces a continuous signal until the alarm is switched to its deactivated condition. A self-locking or latching relay may be provided to maintain the warning means in its energised state. The latching relay may comprise a solid state device and preferably comprises a silicon controlled rectifier or thyristor.

Conveniently, the alarm includes timing means which prevents energisation of the warning means for a predetermined period of time after the alarm has been switched to its activated condition.

The provision of the timing means enables the alarm to be inserted into the cassette recorder or cassette collection after it has been switched to its activated condition without the warning means being accidentally energised by a tilting movement of the body of the alarm. When the alarm has been inserted into the cassette recorder or cassette collection and so soon as the predetermined period of time has expired, any subsequent disturbance of the cassette recorder or cassette collection sufficient to cause a tilting movement of the body of the alarm will energise the warning means.

Alternatively or additionally, the timing means may prevent or delay energisation of the warning means for a predetermined period after the detecting means detects a tilting movement of the body of the cassette.

This enables the cassette to be removed from the cassette recorder or cassette collection without instantaneous sounding of the warning signal and, provided that the alarm is switched to its de-activated condition within the predetermined period, the warning signal will not sound.

Preferably the timing means comprises an integrated circuit.

The switching means for switching the alarm between its activated and de-activated conditions may comprise any convenient form of circuit breaker switch.

Preferably, the circuit breaker switch comprises an electrical connection which is arranged to be broken or completed by the insertion of a key through an aperture in the body of the alarm.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a perspective view of the body of an anti-theft alarm for a video cassette recorder; Figure 2 is a block diagram of the electrical circuit incorporated within the body of the alarm shown in Fig. 1.

The body 1 of the anti-theft alarm shown in Fig. 1 is identical to the shell of a standard video tape cassette intended for use in a video cassette recorder. The body 1 includes the usual features present in the shell of a normal video tape cassette, for example, windows 2 through which, in a normal cassette, the magnetic tape may be seen, an identification label 3 a frangible tab 4 which, in a normal cassette, may be broken off to prevent accidental erasure of the recorded information on the tape, and a hinged flap 1 2 which is normally intended for protecting the tape from dirt and dust particles.

In an alternative embodiment (not shown) the body of the anti-theft alarm is a plastics moulding which conforms with the size and shape of a standard video tape cassette so that it can be inserted into the carriage of a video cassette recorder. The hinged flap 12 may be omitted from the plastics moulding.

The anti-theft alarm of Fig. 1 differs from a normal video tape cassette in that its body 1 contains the electrical circuit of the alarm instead of a magnetic tape wound on two spools within the shell. An aperture 5 is provided in the body, the purpose of which will be described later.

The electrical circuit of the alarm is illustrated schematically in the block diagram shown in Fig. 2.

The electrical circuit comprises a direct current supply 6, a circuit breaker switch 7 for switching the alarm between an activated and a de-activated condition, a tilt detector 8 for detecting a tilting movement of the body of the alarm, a piezo-electric sounder 9 which when energised produced a warning signal, a timer 10 which prevents energisation of the sounder for a predetermined period after the alarm has been switched to its activated condition, and a latching relay 11 which maintains the sounder 9 in its energised state until the alarm is switched to its de-activated condition by the circuit breaker switch 7.

The parts of the electric circuit shown in the block diagram consist of, or can be made up from, standard electrical components. For example, the direct current supply 7 may comprise a 6 Volt battery, the tilt detector 8 may comprise a mercury tilt switch, the timer 10 may comprise a timing circuit and a switching transistor controlled by the output of the timing circuit, and the latching relay 11 may comprise a silicon controlled rectifier or thyristor, the gate or trigger of which is connected to the mercury tilt switch 8. Alternatively, the timer may comprise an integrated circuit which is able to perform the operations of both the timing circuit and the switching transistor.

The circuit breaker switch 7 preferably comprises an electrical connection which is arranged to be broken by the insertion of a key into a complementary socket within the body of the alarm. As shown in Fig. 1 an aperture 5 is provided at a suitable position in the body 1 of the alarm to allow insertion of the key into the socket.

The key preferably comprises a code key that can only activate and de-activate an alarm which has a complementary coded socket.

The key is conveniently in the form of a cylindrical pin which, upon insertion into a complementary socket, forces the contacts of the electrical connection of the circuit breaker switch apart to break the connection. Coded pairs of cylindrical pins and complementary sockets which differ in size and shape may be provided for different alarms so that a particular coded pin can only be used with an alarm that contains a complementary coded socket.

Alternatively, the key may comprise a programmable pin for use with a socket which incorporates a circuit breaker switch that is opened or closed magnetically upon insertion of the pin into, or removal of the pin from, the socket. Many different variations of programmable pins and sockets are available, thus providing a large number of combinations of code keys and coded sockets which may be used.

Alternatively, the switch may comprise an electrical connection which is arranged to be completed by the insertion of a key into the socket in order to deactivate the alarm. The key may then comprise a pin having contacts at its end which are so arranged as to complete the connection within the socket when the key is inserted. Only the key with the correct arrangement of contacts is able to complete the connection.

Normally, at all times when the alarm is not required to be used, the key is inserted into its complementary socket so that the alarm is de-activated.

When the anti-theft alarm is required to be used to protect either a video cassette recor der or a collection of video cassettes against theft, the key is removed from the aperture 5 in the body 1 of the alarm to set the alarm to its activated condition, and then the user of the alarm has a predetermined period set by the timer in which to place the alarm either within the cassette carriage of the video cassette recorder or within a space in the collection of video cassettes.

After the predetermined period has expired, any disturbance of the video cassette recorder or the collection of video cassettes that is sufficient to cause a tilting movement of the body 1 of the alarm will be detected by the tilt detector 8. The tilt detector 8 then triggers the latching relay 11 which in turn energises the sounder 9. The warning signal produced by the sounder 9 indicates that either the video cassette recorder or the collection of video cassettes has been disturbed, and provides a deterrent to a potential thief.

Once the sounder 9 has been energised the latching relay 11 maintains the sounder 9 in its energised state so that it produces a continuous alarm signal. Thereafter the alarm signal can only be turned off by re-insertion of the key through the apertures 5 in the body 1 and into the socket whereby the electrical connection comprising the circuit breaker switch 7 is broken.

The anti-theft alarm according to the present invention therefore provides an effective deterrent to potential thieves of cassette recorders and collections of cassettes since it is almost impossible to remove the cassette recorder without causing a tilting movement of the body of the alarm. Also, when the sounder is energised to sound the warning signal the potential thief is unable to switch off the alarm because he does not have the key to insert into the circuit breaker switch.

In many types of video cassette recorders, it is impossible to eject a cassette from the cassette carriage of the recorder when the power supply to the cassette recorder is switched off. The anti-theft alarm is particularly suitable for protecting these types of video cassette recorders since a thief will not be able to remove the alarm from the cassette recorder once he has disconnected the recorder from its power supply.

The electrical circuit shown in Fig. 2 may be modified by altering the position of the timer 10 to the position indicated by broken lines in Fig. 2. In this position the timer will prevent energisation of the sounder for a predetermined period after the tilt detector 8 detects a tilting movement of the body. This not only allows the alarm to be inserted into the cassette recorder without accidential energisation of the sounder after the key has been removed, but also enables the alarm to be removed from the cassette recorder without instantaneous energisation of the sounder.

In a modified form of the present invention an anti-theft alarm for a collection of cassettes may be incorporated within a body in the form of a protective case for a cassette. When used to protect a collection of cassettes the alarm is set in the same manner as described above with reference to the alarm illustrated in the drawings.

Claims

1. An anti-theft alarm for a cassette recorder, or for a cassette collection, in which the alarm is incorporated within a body in the form of a cassette.

2. An anti-theft alarm for a cassette collection in which the alarm is incorporated within a body in the form of a protective case for a cassette.

3. An anti-theft alarm according to claim 1 or claim 2 comprising detecting means within the body of the alarm for detecting movement of the body, and warning means within the body and responsive to the detecting means for producing an audible warning signal.

4. An anti-theft alarm according to claim 3 in which the detecting means comprises one or more mercury tilt switches.

5. An anti-theft alarm according to claim 3 or claim 4 in which the warning means comprises an electrically energisable sounder.

6. An anti-theft alarm according to claim 5 in which the warning means comprises a piezo-electric sounder.

7. An anti-theft alarm according to any one of claims 3 to 6 which includes switching means for switching the alarm between an activated condition in which the warning means is able to produce an audible warning signal and a de-activated condition in which the warning means is prevented from producing an audible warning signal.

8. An anti-theft alarm according to claim 7 in which the switching means comprises a circuit breaker switch.

9. An anti-theft alarm according to claim 8 in which the circuit breaker switch comprises an electrical connection which is arranged to be broken or completed by the insertion of a key through an aperture in the body of the alarm and into a complementary socket within the body.

10. An anti-theft alarm according to claim 9 in combination with a key in the form of a pin which breaks or completes the electrical connection when it is inserted into the socket within the body.

11. An anti-theft alarm according to any one of claims 7 to 10 in which, once energised to produce a warning signal, the warning means is maintained in its energised state so as to produce a continuous warning signal until the alarm is switched to its de-activated condition.

1 2. An anti-theft alarm according to claim 11 in which a self-locking or latching relay is provided to maintain the warning means in its energised state.

1 3. An anti-theft alarm according to claim 1 2 in which the self-locking or latching relay comprises a silicon controlled rectifier or thyristor.

14. An anti-theft alarm according to any one of claims 7 to 1 3 which includes timing means for preventing energisation of the warning means for a predetermined period of time after the alarm has been switched to its activated condition.

1 5. An anti-theft alarm according to any one of Claims 3 to 1 4 which includes timing means for preventing or delaying energisation of the warning means for a predetermined period of time after the detecting means detects a tilting movement of the body of the alarm.

16. An anti-theft alarm according to claim 1 4 or claim 1 5 in which the timing means comprises an integrated circuit.

1 7. An anti-theft alarm substantially as described herein with reference to the accompanying drawings.