US4503438A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of erasing magnetic latent image in thermo-magnetic recording
Assignee: Fujifilm Business Innovation Corp
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Filing: 1982-08-25
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Granted: 1985-03-05
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Expires: 2002-08-25
Abstract
Abstract A method of erasing a magnetic latent image includes the steps of simultaneously applying an external magnetic field and heat to a thermally magnetized layer of a magnetic recording medium.
Inventors
- 👤 Koichi Saitoh
- 👤 Teruhiko Itami
- 👤 Toshifumi Kimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/852; G01; G01D; G01D15/00; G01D15/12; G03; G03G; G03G19/00; G03G19/005
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
67 words
A method of erasing a magnetic latent image from a thermally magnetized layer of a recording medium having a further magnetized layer storing a magnetization pattern, said method comprising the steps of: applying a magnetic field to said thermally magnetized layer; and simultaneously applying heat to said medium, at least a component of said magnetic field being produced from said magnetization pattern of said further magnetic layer.
Claim 2
Independent Claim
67 words
A method of erasing a magnetic latent image from a thermally magnetized layer of a recording medium having a further magnetized layer storing a magnetization pattern, said method comprising the steps of: applying a magnetic field to said thermally magnetized layer; and simultaneously applying heat to said medium, at least a component of said magnetic field being produced from said magnetization pattern of said further magnetic layer.
Claim 3
Dependent Claim
19 words
A method as claimed in claim 1, said heat and said magnetic field thermally magnetizing said thermally magnetized layer.
Claim 4
Dependent Claim
25 words
A method as claimed in claim 2, wherein at least a portion of said magnetic field comprises a field originating externally of said recording medium.
Claim 5
Independent Claim
95 words
A method of erasing a magnetic latent image, comprising: applying a synergic magnetic field to a thermally magnetized layer of a magnetic recording medium having a further magnetic layer, and simultaneously applying heat to said medium whereby said heat and said synergic magnetic field thermally magnetize said thermally magnetized layer, said synergic magnetic field being composed of at least a component of said further magnetic field and a field originating externally of said recording medium, said external field being applied by means of a roller having a predetermined magnetization pattern at the exterior surface thereof.
Claim 6
Independent Claim
95 words
A method of erasing a magnetic latent image, comprising: applying a synergic magnetic field to a thermally magnetized layer of a magnetic recording medium having a further magnetic layer, and simultaneously applying heat to said medium whereby said heat and said synergic magnetic field thermally magnetize said thermally magnetized layer, said synergic magnetic field being composed of at least a component of said further magnetic field and a field originating externally of said recording medium, said external field being applied by means of a roller having a predetermined magnetization pattern at the exterior surface thereof.
Claim 7
Dependent Claim
17 words
A method as claimed in claim 4, said heating of said medium being effected by said roller.
Claim 8
Dependent Claim
28 words
A method as claimed in claim 4, said external magnetic field changing with a period shorter than that of said periodic magnetization pattern in said further magnetic layer.
Claim 9
Dependent Claim
31 words
A method as claimed in claim 6, wherein wavelengths of said external field (λ 2 ) and said periodic magnetization pattern (λ 1 ) are selected such that λ.sub.2 ≦λ.sub.1 /3.
Claim 10
Dependent Claim
16 words
A method as claimed in claim 5, wherein said roller is heated by internal resistance elements.
Claim 11
Dependent Claim
16 words
A method as claimed in claim 5, wherein said roller is heated by an infrared source.
Claim 12
Dependent Claim
22 words
A method as claimed in claim 4, said magnetization pattern of said roller being formed perpendicularly to a surface of said medium.
Claim 13
Independent Claim
57 words
A method of erasing a magnetic latent image, comprising: applying a synergic magnetic field to a thermally magnetized layer of a magnetic recording medium having a further magnetic layer, and simultaneously applying heat to said medium, at least a a component of said synergic magnetic field derived from a periodic magnetization pattern formed in said magnetic layer.
Claim 14
Independent Claim
57 words
A method of erasing a magnetic latent image, comprising: applying a synergic magnetic field to a thermally magnetized layer of a magnetic recording medium having a further magnetic layer, and simultaneously applying heat to said medium, at least a a component of said synergic magnetic field derived from a periodic magnetization pattern formed in said magnetic layer.
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) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |