US4982302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium and method for magnetic recording and reproduction
Assignee: Fujifilm Holdings Corp
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Filing: 1988-04-08
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Granted: 1991-01-01
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Expires: 2008-04-08
Abstract
Abstract A method for magnetic recording and reproduction comprising the steps of: (1) magnetically multiple-recording signals on a magnetic recording medium comprising a support having thereon an upper magnetic recording layer comprising barium ferrite having an increased coercive force at 60° C. or more and a lower magnetic recording layer comprising at least one of chromium dioxide and Co-modified iron oxide, having a decreased coercive force at 60° C. or more, disposed between said upper magnetic recording layer and said support; (2) heating said magnetic recording layers prior to reproduction due to a reproducing head; and (3) reproducing said magnetically recorded signal from said heated magnetic recording medium which is multiple-recorded.
Inventors
- 👤 Tatsuji Kitamoto
- 👤 Koji Sasazawa
- 👤 Hotaka Minaguchi
- 👤 Hiromichi Shibaya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:55
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/62; G11B5/68; G11B5/70; G11B5/716; G11B5/74; G11B5/78; H; H04; H04N; H04N5/00; H04N5/76; H04N5/78; H04N5/782; H04N5/78213
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
11 words
A method for magnetic recording and reproduction comrpising the steps of:
Claim 2
Independent Claim
11 words
A method for magnetic recording and reproduction comrpising the steps of:
Claim 3
Dependent Claim
102 words
(1) magnetically different layers of recording signals on a magnetic recording medium comprising a support having thereon an upper magnetic recording layer comprising barium ferrite having an increased coercive force at 60° C. or more and a lower magnetic recording layer comprising at least one of chromium dioxide and Co-modified iron oxide having a decreased coercive force at 60° C. or more, disposed between said upper magnetic recording layer and said support; (2) heating said magnetic recording layers prior to reproduction due to a reproducing head; and (3) reproducing said magnetically recorded signals from said heated magnetic recording medium which is multiple-recorded.
Claim 4
Dependent Claim
102 words
(1) magnetically different layers of recording signals on a magnetic recording medium comprising a support having thereon an upper magnetic recording layer comprising barium ferrite having an increased coercive force at 60° C. or more and a lower magnetic recording layer comprising at least one of chromium dioxide and Co-modified iron oxide having a decreased coercive force at 60° C. or more, disposed between said upper magnetic recording layer and said support; (2) heating said magnetic recording layers prior to reproduction due to a reproducing head; and (3) reproducing said magnetically recorded signals from said heated magnetic recording medium which is multiple-recorded.
Claim 5
Dependent Claim
83 words
The method as claimed in claim 1, further comprising the steps of: (1) recording a signal f 1 in at least said lower magentic layer; (2) subsequently recording a signal f 2 having a higher frequency range than said signal f 1 in at least said upper magnetic layer; (3) reproducing said magnetically recorded signal f 1 in a first reproducing step; (4) subsequently heating said magnetic recording layers; and (5) reproducing said magnetically recorded signal f 2 in a second reproducing step.
Claim 6
Dependent Claim
31 words
The method as claimed in claim 1, wherein heating step the temperature of said magnetic recording layers is increased by a temperature in a range from about 10° to 100° C.
Claim 7
Dependent Claim
31 words
The method as claimed in claim 1, wherein the heating means are selected from the group consisting of irradiation of thermal rays, irradiation of infrared rays, or irradiation of laser beams.
References Cited (Backward Citations)
US4340914A
Cited
US4712203A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-31 | 1994-07-02 | 1995-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-31 | 1998-07-02 | 1999-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-31 | 2002-07-02 | 2003-01-01 | $7700.00 | Window Closed / Lapsed |