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US4869797A
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Method for preparing a magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1987-06-18
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Granted: 1989-09-26
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Expires: 2007-06-18
Abstract
Abstract A method of preparing a magnetic recording medium in which a magnetic layer is deposited on a non-magnetic support and then a carbon protective layer is sputtered onto the magnetic layer. The sputtering is performed with a bias voltage of -10V to -100V being applied in the vicinity of the support and magnetic layer.
Inventors
- 👤 Makoto Nagao
- 👤 Kunihiko Sano
- 👤 Fusao Yamanaka
- 👤 Akira Nahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 07:45
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/06; C23C14/22; C23C14/34; G; G11; G11B; G11B5/00; G11B5/84; G11B5/8408
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
86 words
A method of preparing a magnetic recording medium, comprising the steps of: depositing a magnetic layer on a non-magnetic support; sputtering a carbon layer on said magnetic layer; and applying a DC bias voltage to a bias ring during said sputtering, said bias voltage being in a range of from -10 volts to -100 volts, said support having said magnetic layer being wound on a conductive drum, said bias ring being adjacent to said carbon layer and intermediate between said carbon layer and a sputtering target.
Claim 2
Independent Claim
86 words
A method of preparing a magnetic recording medium, comprising the steps of: depositing a magnetic layer on a non-magnetic support; sputtering a carbon layer on said magnetic layer; and applying a DC bias voltage to a bias ring during said sputtering, said bias voltage being in a range of from -10 volts to -100 volts, said support having said magnetic layer being wound on a conductive drum, said bias ring being adjacent to said carbon layer and intermediate between said carbon layer and a sputtering target.
Claim 3
Dependent Claim
20 words
A method as recited in claim 1, wherein said range of said bias voltage is -20 volts to -90 volts.
Claim 4
Dependent Claim
23 words
A method as recited in claim 1, wherein said carbon layer has a thickness in a range of 5 nanometers to 50 nanometers.
Claim 5
Dependent Claim
23 words
A method as recited in claim 5, wherein said magnetic layer has a thickness in a range of 0.03 micrometers to 5 micrometers.
Claim 6
Dependent Claim
23 words
A method as recited in claim 6, wherein said range of said thickness of said magnetic layer is 0.05 micrometers to 1 micrometers.
Claim 7
Dependent Claim
21 words
A method as recited in claim 5, further comprising the step of: maintaining a temperature of said drum above 90° C.
Claim 8
Dependent Claim
17 words
A method as recited in claim 6, wherein said maintaining step maintains said temperature above 120° C.
References Cited (Backward Citations)
US4503125A
Cited
US4428810A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-25 | 1993-03-27 | 1993-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-25 | 1997-03-27 | 1997-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-25 | 2001-03-27 | 2001-09-26 | $7700.00 | Window Closed / Lapsed |