Bizerba-werke Wilhelm Kraut K.g.

Ernst G Hartmann

Hans Krech

Franz Meir

A surveillance system for preventing shoplifting comprises marking elements made of material of high magnetic permeability attached to the goods in a store, and magnetic field generating coils generating a magnetic field in the exit areas from the store. Two different alternating magnetic fields are produced on opposite sides so that the configuration of the field within the exit area is continuously changing. Introduction of a marking element into this area causes different frequencies to be produced which are sensed by a sensing element which then emits a signal. The marking elements can be deactivated during a normal purchase by magnetically saturating the material.

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Hilden, Germany

Ernst G Hartmann