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EP0366335A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Magnetic identifier

Assignee: EMI Group Ltd
•
Filing: 1989-10-18
•
Granted: —
•
Expires: 2009-10-18
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Abstract

Abstract A magnetic identifier for use in an electromagnetic tag comprises a number of permalloy switching elements 1, 2 and 3 disposed on a substrate 4, such as silicon. Respective biasing members 5, 6 and 7 are provided for exerting magnetic bias fields on the elements 1, 2 and 3. The bias fields may differ from one another in any convenient manner so as to cause the elements 1, 2 and 3 to respond in a non-uniform manner to an interrogating field. The arrangement permits a relatively large number of codes to be identified by the use of a small number of elements and a small number of pulse sequences in the interrogating field.

Inventors

  • 👤 David John Sansom

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 07:41
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/06187

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 35 words
A magnetic identifier comprising a plurality of elements of magnetically soft material and respective biasing means for biasing the regions for enabling the regions to exhibit a non uniform response to a common interrogating signal.
Claim 2
Dependent Claim 35 words
A magnetic identifier comprising a plurality of elements of magnetically soft material and respective biasing means for biasing the regions for enabling the regions to exhibit a non uniform response to a common interrogating signal.
Claim 3
Dependent Claim 19 words
An identifier according to Claim 1 wherein the elements and the biasing means are supported on a silicon substrate.
Claim 4
Dependent Claim 15 words
An identifier according to Claim 1 or Claim 2 wherein the elements comprise permalloy material.
Claim 5
Dependent Claim 23 words
An identifier according to any one of Claims 1 to 3 wherein the biasing means comprise a plurality of layers of magnetic material.
Claim 6
Dependent Claim 36 words
An identifier according to any one of the preceding claims wherein at least one of the biasing means has a surface area differing from the surface area of at least one other of the biasing means.
Claim 7
Dependent Claim 38 words
An identifier according to any one of the preceding claims wherein at least one of the biasing means comprises a magnetic material having a coercivity differing from the coercivity of at least one other of the biasing means.
Claim 8
Dependent Claim 53 words
An identifier according to any one of the preceding claims wherein the plurality of elements are arranged as an array and wherein the biasing means are arranged such that the outermost elements of the array have substantially equal and opposite biases applied thereto and differing from the bias applied to the other elements.
Claim 9
Dependent Claim 67 words
An identifier according to any one of the preceding claims wherein the plurality of elements comprise a set of elements, the elements of the set having the easy axis of magnetisation of the magnetically soft material in substantial alignment, the identifier comprising a plurality of sets of the elements disposed such that the easy axes of the sets are disposed substantially orthogonal with respect to each other.
Claim 10
Dependent Claim 18 words
An identifier according to any one of the preceding claims wherein the plurality of elements comprises three elements.

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