An anti-tamper device

Abstract

 An anti-tamper device for use with a security detection apparatus and provided with timer means (12) and detector means (14). Upon the detection of a person or article by the detector means, said means initiate the timer means. timer means (12) sare arranged such that this means initiates the operation of an alarm device (16) if an expected subsequent movement of the person or article does not occur after initiation of the timer means and within a time period set in the timer means.

Description

[0001] This invention relates to an anti-tamper device and, more especially, this invention relates to anti-tamper device for use with security detection apparatus. The security detection apparatus may be electromagnetic detection apparatus for use in anti-theft security applications.

[0002] Electromagnetic detection systems for use in anti-theft security applications are well known. The electromagnetic detection systems operate by generating a low frequency strong magnetic field between two antennae. The systems are activated by appropriate targets which may be, for example, a metal strip. The metal strip may be an amorphous metal strip. The systems are frequently used for the protection of a wide variety of articles in department stores, libraries, do-it-yourself shops, drug stores, computer rooms and data libraries.

[0003] The known electromagnetic detection systems are not always sufficiently efficient in detecting the target, for example the metal strip target. More specifically, the systems can be easily defeated by passing the target very quickly, thereby not giving the system time to analise the target and generate an alarm if appropriate. Thus a thief who runs through the system may not be detected. It is also sometimes possible for a person to walk through a known electromagnetic detection system sufficiently slowly with a target carefully held without raising an alarm. Furthermore, articles provided with the targets can sometimes be slid along the floor in order to bypass the electromagnetic detection field.

[0004] In the majority of applications of the known electromagnetic detection systems, the above mentioned methods of attempting to defeat the systems usually require the potential thief to act in a strange manner which is observed. There are however some situations such as in security conscious buildings, for example computer rooms or data libraries, where the potential thief may not be under constant observation and where it is important not to defeat the system.

[0005] It is an aim of the present invention to obviate or reduce the above mentioned problem.

[0006] Accordingly, this invention provides an anti-tamper device for use with security detection apparatus, which anti-tamper device comprises timer means and detector means for initiating operation of the timer means consequent upon the detection of a person or article, and the timer means being such as to initiate the operation of an alarm if an expected subsequent movement of the person or article does not occur after initiation of the timer means and within a time period set in the timer means.

[0007] Preferably, the anti-tamper device includes at least one first reflector and retroreflective scan sensor arrangement for detecting the person or article, and includes at least one second reflector and retroreflective scan sensor arrangement for detecting the expected subsequent movement.

[0008] The anti-tamper device may be one in which the timer means is such as to initiate operation of the alarm if the person or article interrupts a first sensor beam from the first reflector and retroreflective scan arrangement and does not interrupt in the time period a second sensor beam from the second reflector and retroreflective scan arrangement, or if the person or article only separately interrupts the first or the second sensor beam. The first sensor beam may be a front sensor beam and the second sensor beam may be a rear sensor beam. The first and the second sensor beams may be positioned other than in the front and the rear respectively as may be desired.

[0009] The timer means may be an integrated circuit with alarm outputs. Other types of timer means may however be employed.

[0010] The timer means may comprise time period adjuster means whereby the timer means can be provided with different time periods.

[0011] The time period adjuster means is preferably at least one variable potentiometer.

[0012] The timer means may be provided with a housing having a display. Preferably the display is a light emitting diode display. Other types of display may be employed. The display preferably gives the status condition of the anti-tamper device.

[0013] The anti-tamper device may be one in which the housing has a lid, and in which the housing is provided with relay means for generating an alarm consequent upon the unauthorised opening of the lid. The relay means is preferably a micro switch. Other types of relay means may be employed.

[0014] Preferably, the detector means is a form of anti-shoplifting device utilising antenna to produce the detection field. The detection field may be either electromagnetic or radio frequency.

[0015] Preferably, the anti-tamper device comprises more than one first sensor beam in the first reflector and retroreflective scan arrangement, and more than one sensor beam in the second reflector and retroreflective scan arrangement. Generally, the more beams that are employed, the greater will be the level of security afforded by the anti-tamper device.

[0016] The present invention also extends to security detection apparatus when provided with the anti-tamper device.

[0017] The security detection apparatus may be electromagnetic detection apparatus such for example as for use in anti-theft security applications. Other types of security detection apparatus may however be provided with the anti-tamper device.

[0018] An embodiment of the invention will now be described solely by way of example and with reference to the accompanying drawings in which:

Figure 1 shows electromagnetic security detection apparatus provided with reflectors and retroreflective scan sensors which form part of an anti-­tamper device; and

Figure 2 is a block diagram showing the anti-tamper device and its connection to the electromagnetic security detection apparatus.

[0019] Referring to Figure 1, there is shown electromagnetic security detection apparatus 2 comprising a frame 4. The detection apparatus 2 operates by generating a low frequency strong magnetic field between two antennae formed by the frame 4. The detection apparatus 2 is such that persons wishing to remove articles from an establishment such for example as a computer room or a data library are required to pass with the article through the frame 4. A metallic target strip on the article is detected by the detection apparatus 2 in a known manner. More specifically, the detector apparatus 2 also comprises a control box 6 which is made of metal and which houses transmitter and receiver electronics. The transmitter generates a very low frequency strong magnetic field between the antennae, the antennae being basically coils of wires. When the target strip enters the electromagnetic field, it is saturated. The receiver section in the control box 6 monitors the characteristics of the target strip under saturation and generates an alarm if the characteristics coincide.

[0020] The present invention provides an anti-tamper device 8 which comprises a control box 10. The control box 10 is made of a plastics material. The control box is provided with a lid which is fitted with relay means in the form of a micro switch. The micro switch generates an alarm if the lid is opened or removed.

[0021] As can be seen from Figure 2, the control box 10 comprises timer means in the form of a timer circuit 12.

[0022] The control box 10 also comprises detector means in the form of a signal input detector device 14. The signal input detector device 14 is for initiating operation of the timer means consequent upon the detection of a person or article. The timer circuit 12 is such, as to initiate operation of an alarm via an alarm out device 16 if an expected subsequent movement of the person or if article does not occur after the initiation of the timer circuit 12 and within a time period set in the timer circuit 12.

[0023] Figure 2 shows how the anti-tamper device 8 is provided with first, second and third reflector and retroreflective scan sensor arrangements 18,20,22. Each reflector and retroreflective scan sensor arrangement 18,20,22 comprises a reflector 24 and a retroreflective scan sensor 26 which includes transmitter/receiver apparatus. Figure 1 illustrates the position of the reflectors 24 and the retroreflective scan sensors 26.

[0024] The control box 10 may include a light emitting diode display. The alarm can be visual and/or audible. The timer circuit 12 is activated by closed circuit switch operations. Time slots are adjusted by variable potentiometers (not shown) fitted on to the circuit board of the timer integrated circuit.

[0025] In operation of the anti-tamper device 8, if a person or article breaks any of the front beams generated by the retro-reflective scan sensors 26, a contact is made which activates the timer circuit 12. If the rear beams generated by the retroereflective scan sensors 26 are not broken within the exact time allocation in the timer circuit 12, then the alarm system is activated. If either the front or the rear beam is broken individually, then the alarm is again activated.

[0026] The alarm system is thus effective to help prevent persons attempting to defeat the detection apparatus 2 by passing through the frame 4 very slowly or very quickly, or by passing articles along the ground to try and pass underneath the electromagnetic detection field. Thus, when the anti-tamper device 8 is fitted to the detection apparatus 2, the detection security afforded by the detection apparatus 2 is considerably increased.

[0027] It is to be appreciated that the embodiment of the invention described above with reference to the accompanying drawings has been given by way of example only and that modifications may be effected. Thus, for example, the anti-tamper device 8 can be made in any desired size. The anti-tamper device 8 can be used with various types of security detection apparatus and it is not restricted to use with the detection apparatus 2. The anti-tamper device 8 can be produced such that sit is possible to differentiate between alarms caused by the detection apparatus 2 and alarms caused by the anti-tamper device 8. Various types of retroreflective scan sensors may be employed. Should any wiring to the anti-tamper device be disconnected, or tampered with, the alarm circuit will activate. A battery back up facility may be provided for use in the event of a mains fail condition.

Claims

1. Anti-tamper device for use with security detection apparatus, characterised by timer means and detector means for initiating operation of the timer means consequent upon the detection of a person or article, and the timer means being such as to initiate the operation of an alarm if an expected subsequent movement of the person or article does not occur after initiation of the timer means and within a time period set in the timer means.

2. Anti-tamper device according to claim 1, characterised by at least one first reflector and retroreflective scan sensor arrangement for de­tecting the person of article, and includes at least one second reflect­or and retroreflective scan sensor arrangement for detecting the expect­ed subsequent movement.

3. Anti-tamper device according to claim 1 or 2, characterised in that the timer means is such as to initiate operation of the alarm if the person or article interrupts a first sensor beam from the first reflector and retroreflective scan arrangement and does not interrupt in the time period a second sensor beam from the second reflector and retroreflective scan arrangement, or if the person or article only separately interrupts the first or the second sensor beam.

4. Anti-tamper device according to claim 3, characterised in that the first sensor beam is a front sensor beam and the second sensor beam is a rear sensor beam.

5. Anti-tamper device according to one of the claims 1-4, character­ised in that the timer means are constituted by an integrated circuit With alarm outputs.

6. Anti-tamper device according to one of the claims 1-5, character­ised in that the timer means comprise time period adjuster means whereby the timer means can be provided with different time periods.

7. Anti-tamper device according to claim 6, characterised in that the time period adjuster means is at least one variable potentiometer.

8. Anti-tamper device according to one of the claims 1-6, character­ised in that the timer means are provided with a housing having a dis­play.

9. Anti-tamper device according to claim 8, characterised in that the housing has a lid, in which the housing is provided with relay means for generating an alarm consequent upon the unauthorized opening of the lid.

10. Anti-tamper device according to one of the claims 1-9, character­ised in that the detector means is a form of anti-shoplifting device utilising antenna to produce the detection field.

11. Anti-tamper device according to one of the claims 3-10, character­ised in that more than one first sensor beam in the first reflector and retroreflective scan arrangement and more than one sensor beam in the second reflector and retroreflective scan arrangement.

12. Security detection apparatus provided with the anti-tamper device according to one of the preceeding claims.

Drawing