Apparatus for deactivation of electronic article surveillance tags
AssigneeSensormatic Electronics Corporation
InventorRonald B. Easter
Life of this patent
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Abstract
A deactivator for deactivating electronic article surveillance tags includes a deactivating coil, drive circuitry controllable for supplying driving signals to the deactivating coil, a reference signal generator for generating a reference signal having preselected characteristics varying with time, a comparator for comparing characteristics of the driving signals with the reference signal characteristics, and a control unit for controlling the drive circuitry in accordance with signal comparisons effected by the comparator.
Claims14
A deactivator for deactivating electronic article surveillance tags, comprising:
- (a) a deactivating coil;
- (b) drive means controllable for supplying diving current signals to said deactivating coil;
- (c) reference signal generator means for generating a continuous reference signal having preselected characteristics of decreasing amplitude over time;
- (d) comparator means for comparing amplitude characteristics of said driving current signals with said reference signal amplitude characteristics;
- and
- (e) control means for controlling said drive means in accordance with signal comparisons effected by said comparator means to selectively change the direction of said driving signals to conform an envelope of said driving current signals to said reference signal amplitude characteristics.
A method for generating a magnetic field for use in deactivating electronic article surveillance tags, comprising the steps of:
- (a) providing a deactivation coil;
- (b) generating an analog signal having amplitude continuously varying with time from a given maximum to a given minimum in a specified time interval;
- (c) generating a continuous driving signal current selectively changing in direction for said deactivation coil to have an amplitude envelope varying with time correspondingly with said amplitude of said analog signal;
- and
- (d) supplying said continuous driving signal current to said deactivation coil and thereby establishing a magnetic field selectively changing in direction and decaying from a given maximum to a given minimum in said specified time interval.
Dependencies are inferred from the claim text.