Anti-theft element

Details Anti-theft element Anti-theft element

2000-10-05

2002-02-19

Wu, Daniel J. (Department: 2632)

Communications: electrical

Condition responsive indicating system

Specific condition

C340S572600, C340S572800

Reexamination Certificate

active

06348865

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention pertains to an anti-theft element for acoustomagnetic security systems, with said anti-theft element containing a module that is arranged in a housing and consists of at least one magnetic element and a thin metal plate.
Anti-theft elements of this type which are used in so-called acoustomagnetic systems and also referred to as AM labels are generally known and broadly utilized. They serve for identifying the merchandise, onto which such labels are applied or into which such labels are incorporated.
Known AM labels consist of a plastic housing, a thin metal plate and a thin magnetic plate. The magnetic plate has a north-south polarization, and the metal plate is positioned at an exactly defined distance from the magnetic plate. The dimensions of both plates are exactly predetermined. The tolerances lie on the order of tenths of a millimeter.
Acoustomagnetic system locks which consist of transmission and reception units detect the resonance at a frequency of approximately 58 kHz of such labels and trigger. In order to prevent the triggering of such labels, high ac currents are generated by means of large copper coils in order to erase the north-the south pole structure on the magnetic strips. Due to this measure, the acoustomagnetic system locks no longer respond.
However, labels of this type can also be very easily manipulated, e.g., by means of malicious deactivation.
Certain areas are particularly susceptible to theft, e.g., CD departments of department stores, music stores and the like. In this case, another system is used instead of labels that can be deactivated, with the labels being arranged in so-called safers that remains in the store. However, the anti-theft systems can also be manipulated in this case by exerting pressure, mechanical bending or the previously described erasing of the polarization of the magnetic strips.
SUMMARY OF THE INVENTION
In light of the previously described state of the art, the present invention is based on the objective of making available an anti-theft element which largely precludes manipulations without enlarging the structural shape of the element.
According to the invention, this objective is attained by additionally developing an anti-theft element of the initially described type in such a way that it cannot be deactivated, i.e., the anti-theft element is realized such that it remains permanently activated.
This objective is attained due to the fact that flexible magnetic foils are accommodated in the label housing with different pole alignments such that the standard magnetic plate can be eliminated. It was surprisingly determined that flexible magnetic strips, namely one magnet strip with a north pole alignment and one magnetic strip with a south pole alignment which are arranged on opposite sides of the label, can be adjusted to a frequency of approximately 58 kHz together with the metal plate. In this respect, the dimensions of the magnetic strips and their distance from the metal plate are important. It proved to be particularly advantageous to utilize strips of magnetic foil with a height of approximately 1.4 mm, a length of approximately 1.5 cm and a width of approximately 2 mm. These strips are arranged on diagonally opposite sides of the labels. It was surprisingly determined that labels of this type can no longer be deactivated with conventional deactivation units.
Such permanently active labels consequently are particularly suitable for systems, in which the anti-theft element remains within a secured area. This means that special housings, so-called safers, can be provided with labels according to the invention such that the safer labels can no longer be manipulated. This results in an increased security. The structural shapes are not enlarged, with miniaturized versions of the label also being possible. The manufacturing expenditure is maintained at a low level.


REFERENCES:
patent: 4510489 (1985-04-01), Anderson, III et al.
patent: 4510490 (1985-04-01), Anderson, III et al.
patent: 4965689 (1990-10-01), Normann et al.
patent: 5495230 (1996-02-01), Lian
patent: 5594420 (1997-01-01), Copeland et al.
patent: WO 90/03652 (1990-04-01), None

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