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—
JurisdictionEP
Data Sourcegoogle_patents
Last Synchronized2026-11-09 07:55
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.
References Cited (Backward Citations)
No citation records indexed.
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