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US4403138A
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Heat-destructible magnetic memory element
Assignee: Thales Avionics SAS
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Filing: 1981-05-15
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Granted: 1983-09-06
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Expires: 2001-05-15
Abstract
Abstract Magnetic memory element for transport ticket or credit card, comprising a support and at least one ferromagnetic layer containing at least one piece of information recorded therein and a layer of a non-magnetic diffuser in contact with the ferromagnetic layer to irreversibly destroy the magnetism of the ferromagnetic layer when the element is heated.
Inventors
- 👤 Claude Battarel
- 👤 Brigitte Bedene
- 👤 Robert Morille
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:16
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10; G06K19/12; G06K1/00; G06K1/12; G06K1/125; G06K19/02; G06Q; G06Q20/00; G06Q20/30; G06Q20/34; G06Q20/343; G06Q20/3433; G07; G07F; G07F7/00; G07F7/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
75 words
A magnetic memory element, comprising a support, at least one ferromagnetic layer on said support containing at least one piece of information recorded therein and at least one layer of a non-magnetic diffuser in contact with said ferromagnetic layer, each said diffuser layer being operable, when heated, to diffuse said non-magnetic diffuser from a said diffuser layer into a said ferromagnetic layer associated therewith and thus irreversibly destroy the magnetism of said associated ferromagnetic layer.
Claim 2
Dependent Claim
75 words
A magnetic memory element, comprising a support, at least one ferromagnetic layer on said support containing at least one piece of information recorded therein and at least one layer of a non-magnetic diffuser in contact with said ferromagnetic layer, each said diffuser layer being operable, when heated, to diffuse said non-magnetic diffuser from a said diffuser layer into a said ferromagnetic layer associated therewith and thus irreversibly destroy the magnetism of said associated ferromagnetic layer.
Claim 3
Dependent Claim
13 words
The element of claim 1, wherein said ferromagnetic layer is a thin layer.
Claim 4
Dependent Claim
30 words
The element of claim 1, wherein the concentration of said non-magnetic diffuser required for said irreversible destruction is less than the solubility of said non-magnetic diffuser in said ferromagnetic layer.
Claim 5
Dependent Claim
30 words
The element of claim 2, wherein the concentration of said non-magnetic diffuser required for said irreversible destruction is less than the solubility of said non-magnetic diffuser in said ferromagnetic layer.
Claim 6
Dependent Claim
23 words
The element of claim 2, wherein a plurality of said thin ferromagnetic layers are alternatingly superposed with a plurality of said diffuser layers.
Claim 7
Dependent Claim
23 words
The element of claim 3, wherein a plurality of said thin ferromagnetic layers are alternatingly superposed with a plurality of said diffuser layers.
Claim 8
Dependent Claim
11 words
The element of claim 1, wherein said ferromagnetic layers are discontinuous.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-05 | 1987-03-07 | 1987-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-05 | 1991-03-07 | 1991-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-05 | 1995-03-07 | 1995-09-06 | $7700.00 | Window Closed / Lapsed |