# US 5,347,508 A · Optical information storage disk for use with electronic article surveillance systems

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,347,508 A
- Document ID: US5347508A
- Status: Granted
- Kind: A
- Application number: 07/872,151
- Filed: 1992-04-22
- Granted: 1994-09-13
- Earliest claimed: 1992-04-22
- Assignees: Minnesota Mining and Manufacturing Company
- Inventors: David P. Montbriand; Peter J. Zarembo
- Web page: https://patentgrep.com/patent/US5347508A

## CPC

- G11B 23/286: {Antitheft arrangements, e.g. Electronic Article Surveillance [EAS] tags}
- G08B 13/2408: {using ferromagnetic tags}
- G08B 13/2434: {Tag housing and attachment details}
- G08B 13/2437: {Tag layered structure, processes for making layered tags}
- G08B 13/2442: {Tag materials and material properties thereof, e.g. magnetic material details}
- G08B 13/2445: {Tag integrated into item to be protected, e.g. source tagging}
- G11B 7/24: Record carriers characterised by shape, structure or physical properties, or by the selection of the material (characterised by the arrangement of information on the carrier G11B7/007)
- G11B 23/0042: {with provision for auxiliary features (sensing such features G11B17/00, G11B19/02)}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

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.

## Claims

### Claim 1

An optical information disk of the type comprising a generally planar, generally annular first disk surface and an opposed, generally annular second disk surface oriented generally parallel to said first disk surface, an outer, generally circular peripheral rim extending between said first and second disk surfaces and structure defining a generally centered aperture extending between said first and second disk surfaces and a plurality of generally concentric data tracks optically accessible from at least one of said disk surfaces, wherein said disk is further adapted for use with a magnetic electronic surveillance system to prevent unauthorized removal of said disk from an access restricted location, said disk further comprising a generally annular, magnetic electronic surveillance marker carried about said aperture and means for securing said marker to said disk without impairing the operability of said disk, wherein said disk includes structure defining a groove in said first disk surface including a generally cylindrical groove inner wall oriented generally normal to said first disk surface, an opposed, generally cylindrical groove outer wall oriented generally normal to said first disk surface, and a generally annular bottom wall oriented generally parallel to said first disk surface extending between said inner and outer groove walls and wherein said marker is positioned within said groove.

### Claim 2 (depends on 1)

A disk according to claim 1, said marker including a generally annular marker upper surface and an opposed, generally annular marker lower surface, said securing means including adhesive means for adhering said marker lower surface to said groove bottom wall.

### Claim 3 (depends on 1)

A disk according to claim 1, said securing means including a sealing compound applied across said first surface and bondingly received within said groove for immovably sealing said marker in said groove.

### Claim 4 (depends on 3)

A disk according to claim 3, said sealing compound comprising a lacquer coating.

### Claim 5 (depends on 1)

A disk according to claim 1, wherein said marker comprises:
(a) a first annulus of a high permeability, low coercive force material having a plurality of magnetic switching areas into which flux collected from adjacent areas is concentrated, thereby enabling a characteristic, readily distinguishable response to be created upon reversal of the magnetic state within at least one switching area.

### Claim 6 (depends on 5)

A disk according to claim 5, wherein said marker further comprises a second annulus substantially coextensive with said first annulus and formed of a relatively high coercive force material which, when magnetized, alters said characteristic response from that resulting when unmagnetized.