Magnetic materials for security applications

• US 5,368,948 A
• Filed: 04/09/1993
• Issued: 11/29/1994
• Est. Priority Date: 01/09/1989
• Status: Expired due to Fees

• Current Assignee: Esselte METO International Produktions
• Original Assignee: Esselte METO International Produktions
• Inventors: Davies, Dafydd G.
• Primary Examiner(s): Lewis, Michael
• Assistant Examiner(s): KALINCHAK, STEPHEN
• Application Number:
  US08/044,111
• Time in Patent Office: 599 Days
• Field of Search: 340/572, 340/551, 428/601, 428/626, 428/611, 324/262
• US Class Current: 428/611
• CPC Class Codes: G08B 13/2411 Tag deactivation
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2437 Tag layered structure, processes for making layered tags
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details
• CPC Class Codes: H01F 41/26 using electric currents , e.g. electroplating
• CPC Class Codes: Y10T 428/12396 Discontinuous surface component
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape

Abstract

A tag or marker is disclosed which comprises a substrate; an `active` magnetic material which is a soft magnetic material having a high magnetic permeability and a low coercive force; and a deactivating material which is a hard or semi-hard magnetic material having a moderate or high coercive force and a moderate magnetic permeability, whereby the deactivating material, when subjected to a sufficiently high magnetising force, is able to clamp the magnetic properties of the `active` material so as to deactivate the `active` material. The tag or marker is characterised in that the deactivating material is formed by an electrodeposition process, and in that the deactivating layer is nickel.

Claims

1. A magnetically active tag or marker which comprises a substrate;

an `active` magnetic material which is a soft magnetic material having a high magnetic permeability and a low coercive force; and

a deactivating material which is a hard or semi-hard magnetic material having a moderate or high coercive force and a moderate magnetic permeability, whereby the deactivating material, when subjected to a sufficiently high magnetizing force, is able to clamp the magnetic properties of the `active` material so as to deactivate the `active` material, characterized in that said deactivating material consists of nickel with a columnar crystal grain structure and substantially isotropic magnetic properties in the plane of said substrate, said deactivating material being formed by electrodeposition, electroforming or electroless chemical deposition.

2. A tag or marker as claimed in claim 1, characterised in that said deactivating material is formed as a discontinuous foil or layer or as a plurality of islands carried by a substrate, by means of an electrodeposition process in which selective deposition is achieved by a masking technique.

3. A tag or marker as claimed in claim 1, characterized in that said deactivating material is planar and has a columnar grain structure and substantially isotropic magnetic properties in the plane of said deactivating material.

5. A tag or marker as claimed in claim 1, characterised in that said deactivating material is subjected to a deformation process after being formed by an electrodeposition method.

6. A tag or marker as claimed in claim 1, characterised in that said deactivating material has been subjected to a stamping, rolling, pressing or embossing process.

7. A tag or marker as claimed in claim 1, characterised in that said deactivating material is subjected to mechanical deformation or cold working.

8. A tag or marker as claimed in claim 1, characterised in that a portion of the area of said deactivating material has been subjected to said deformation process.

4. A tag or marker as claimed in 1, characterised in that said columnar grain structure is coated with a thin layer of a planar crystal grain structure.