US 5,969,612 A · Stabilizing the position of an active element in a magnetomechanical EAS marker

Abstract

A magnetomechanical EAS marker is formed of a housing, a magnetostrictive active element in the housing and a bias element fixedly mounted on the housing. A central portion of the active element is secured to the housing to keep the active element from shifting in a longitudinal direction relative to the bias element and to keep ends of the active element spaced from the housing. The active element remains free to mechanically resonate in response to an EAS interrogation signal. The stable positioning of the active element prevents variations in the bias magnetic field due to shifting relative to the bias element, while keeping ends of the active element free from frictional damping due to mechanical loading from contact with the housing.

Claims17

Dependent claims

A magnetomechanical electronic article surveillance system, comprising:

(a) generating means for generating an electromagnetic field alternating at a selected frequency in an interrogation zone, said generating means including an interrogation coil;
(b) a marker secured to an article of merchandise appointed for passage through said interrogation zone, said marker including a housing for defining a cavity, a magnetostrictive metal strip in said cavity, means for securing a central portion of said magnetostrictive strip to said housing, and bias means for providing a biasing magnetic field such that said magnetostrictive strip is mechanically resonant when exposed to said alternating field;
and
(c) detecting means for detecting said mechanical resonance of said magnetostrictive element.

1 more element

Dependencies are inferred from the claim text.

Stabilizing the position of an active element in a magnetomechanical EAS marker

Life of this patent

Stabilizing the position of an active element in a magnetomechanical EAS marker

Life of this patent

Abstract

Claims17