摘要:
A novel sensor element having low magnetic coercivity and an asymmetric hysteresis characteristic is formed by heating a strip of cobalt alloy in an exidizing atmosphere to form an oxide coating thereon and then the strip is cooled in the presence of a magnetic field of about 0.3 oersteds along its length. The strip is detected by subjecting it to an alternating magnetic interrogation field and passing the resulting magnetic disturbances through signal processing circuits which select pulses produced only once in each interrogation field cycle. The element is deactivated by subjecting it to a magnetic field which eliminates its asymmetry.
摘要:
Articles of merchandise (42) which contain deactivatable theft detection targets (44) have their targets deactivated by passing them through a box-like apparatus (30) made of low coercive force, high saturation induction material with a multiplicity of permament magnets (48) on its inside surfaces so as to generate magnetic fields which extend at different directions and at decreasing intensities from one end of the apparatus to the other so that irrespective of a target's orientation while passing through the apparatus, the target's magnetic deactivation slugs or elements will encounter a magnetizing field along the target's length sufficient to magnetize the elements.
摘要:
An antenna system for an electronic article surveillance system, comprising: a first, tunable transmitting loop; a second, tunable transmitting loop, the first and second transmitting loops being arranged for first and second modes of operation, the transmitting loops being field-coupled to one another such that tuning the antenna system for one of the modes of operation detunes the antenna system for the other mode of operation; a tunable compensation coil field-coupled to each of the first and second transmitting loops, the tunable compensation coil enabling the antenna system to be tuned for operation in one of the modes at a first resonant frequency, and despite the detuning, enabling the antenna system to be tuned for operation in the other of the modes at a second resonant frequency independently of the tuning for the first mode of operation. The first and second resonant frequencies can be the same as or different from one another. One of the first and second modes of operation is as an in-phase rectangular loop and the other of the first and second modes of operation is as a "figure-8". The compensation loop encircles the first and second transmitting loops.
摘要:
A deactivatable electronic theft detection marker is made from a strip or ribbon of high magnetic permeability strip or ribbon and then high magnetic coercivity material is deposited on the strip or ribbon by electroplating.
摘要:
Items of merchandise (30) are protected from shoplifting or theft by affixing to them special responder targets (32), which are formed by drawing a material of high magnetic permeability into a thin wire and thereafter rolling the wire into a flattened strip and annealing the strip and severing the strip into individual lengths. The flattened strip may be positioned on an adhesively coated base strip (42) and covered by a peel strip (46). Slug-like deactivation elements (48) of hard magnetic material may be positioned along the strip for deactivating it.