US4652460A
Expired / Lapsed
US
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Process for preparing magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1986-04-10
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Granted: 1987-03-24
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Expires: 2006-04-10
Abstract
Abstract A process for preparing a magnetic recording medium by forming a ferromagnetic thin film on a non-magnetic support moving along a rotating drum by a vapor deposition method is disclosed, comprising introducing a first oxidizing gas and then introducing a second oxidizing gas near the surface of the ferromagnetic film moving along the rotating drum and glow-discharging the second oxidizing gas, using a charging energy (G) for glow discharge per unit area of a ferromagnetic thin film surface of 1.0 W·sec/cm 2 or more.
Inventors
- 👤 Ryuji Shirahata
- 👤 Yoshihiro Arai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:28
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/85
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
128 words
A process for preparing a magnetic recording medium by forming a ferromagnetic thin film on a non-magnetic support moving along a rotating drum by a vapor deposition method, comprising introducing a first oxidizing gas and then introducing a second oxidizing gas near the surface of the ferromagnetic film moving along the rotating drum and glow discharging the second oxidizing gas, using a charging energy (G) for glow discharge per unit area of a ferromagnetic thin film surface of 1.0 to 5.0 W·sec/cm 2 , wherein the ferromagnetic thin film is formed on the non-magnetic support moving along the rotating drum by an oblique incident evaporation method while introducing the first oxidizing gas near the place where vapor flow of ferromagnetic metal is deposited at the minimum incident angle.
Claim 2
Dependent Claim
128 words
A process for preparing a magnetic recording medium by forming a ferromagnetic thin film on a non-magnetic support moving along a rotating drum by a vapor deposition method, comprising introducing a first oxidizing gas and then introducing a second oxidizing gas near the surface of the ferromagnetic film moving along the rotating drum and glow discharging the second oxidizing gas, using a charging energy (G) for glow discharge per unit area of a ferromagnetic thin film surface of 1.0 to 5.0 W·sec/cm 2 , wherein the ferromagnetic thin film is formed on the non-magnetic support moving along the rotating drum by an oblique incident evaporation method while introducing the first oxidizing gas near the place where vapor flow of ferromagnetic metal is deposited at the minimum incident angle.
Claim 3
Dependent Claim
16 words
A process as in claim 1, wherein the minimum incident angle is from 20° to 75°.
Claim 4
Dependent Claim
76 words
A process as in claim 1, wherein a ratio Δp 2 /Δp 1 is adjusted to 5/1 or more, in which Δp 1 is the increase of pressure due to introducing the first oxidizing gas near the place where the vapor flow of ferromagnetic metal is deposited at the minimum incident angle and Δp 2 is the increase of pressure due to introducing the second oxidizing gas near the surface of a vapor-deposited ferromagnetic thin film.
Claim 5
Dependent Claim
18 words
A process as in claim 3, wherein the ratio Δp 2 /Δp 1 is from 5/1 to 50/1.
Claim 6
Dependent Claim
18 words
A process as in claim 3, wherein the ratio Δp 2 /Δp 1 is from 5/1 to 30/1.
Claim 7
Dependent Claim
94 words
A process as in claim 3, wherein said ferromagnetic thin film is formed by said vapor deposition method, whereafter said first oxidizing gas is introduced in a first area after formation of said ferromagnetic thin film; said ferromagnetic thin film then travels from said first area to a second area, and in said second area said second non-oxidizing gas is passed through means for glow discharging the second oxidizing gas, said vapor deposition means and said means for glow discharging being operated under conditions such that the ratio ΔP 2 /ΔP 1 is met.
Claim 8
Dependent Claim
48 words
A process as in claim 6, wherein said first and second oxidizing gases are selected from O 2 , NO 2 , CO 2 , H 2 O or a gas mixture of oxygen and another gas selected from the group consisting of Ar and N 2 .
Claim 9
Dependent Claim
42 words
A process as in claim 6, wherein the pressure in said first area and second area is in the range of from 1×10 6 to 2×10 4 Torr excluding the pressure attributable to said first oxidizing gas and said second oxidizing gas.
Claim 10
Dependent Claim
31 words
A process as in claim 1, wherein the charging energy (G) used for glow discharge per unit area of a ferromagnetic thin film is from 1.0 to 3.0 W·sec/cm 2 .
Claim 11
Dependent Claim
37 words
A process as in claim 1, wherein said first and second oxidizing gases are selected from the groups consisting of an oxygen gas, an oxygen-containing compound gas, and a gas mixture of oxygen gas and another gas.
References Cited (Backward Citations)
US4477489A
Cited
US4511594A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1990-03-23 | 1990-09-22 | 1991-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-23 | 1994-09-22 | 1995-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-23 | 1998-09-22 | 1999-03-24 | $7700.00 | Window Closed / Lapsed |