OPTICAL INFORMATION STORAGE DISK FOR USE WITH ELECTRONIC ARTICLE SURVEILLANCE SYSTEMS

摘要

An optical information storage disk especially adapted for tamper-proof monitoring by an electronic article surveillance (EAS) system. The compact disk hereof includes a generally planar, annular first disk surface and an opposed, generally annular second disk surface, a plurality of generally concentric data tracks on at least one of the disk surfaces, a centered aperture and a generally annular EAS magnetic marker concentrically oriented about the centered aperture. The annular EAS marker comprises a dual status, multi-directional marker with a selectively demagnetizable, essentially linear magnetic switching field. The marker is preferably received within a grooved recess in one of the disk surfaces and is immovably retained within the grooved recess by a coating covering the disk surface.