Patent US1854132A successfully refreshed from Google Patents.
US3929604A
Expired / Lapsed
US
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Method for producing magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1974-07-25
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Granted: 1975-12-30
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Expires: 1994-07-25
Abstract
Abstract A method for producing a magnetic recording medium by ionicplating having generally uniform magnetic characteristics in every direction comprising generating in a vacuum chamber and in a magnetic field a plasma of the glow discharge of a gas between a negatively-charged magnetic recording medium substrate and a positively-charged evaporative source of a ferromagnetic material and positioning the substrate in a magnetically concentrated zone of the plasma which is concentrated by the magnetic field, whereby the ferromagnetic material is evaporated and deposited on the magnetic recording medium substrate.
Inventors
- 👤 Ryuji Shirahata
- 👤 Tatsuji Kitamoto
- 👤 Mahito Shimizu
- 👤 Akira Tasaki
- 👤 Masaaki Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:20
CPC Classifications
H; H01; H01F; H01F10/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
87 words
A METHOD FOR PRODUCING A MAGNETIC RECORDING MEDIUM BY IONIC-PLATING HAVING GENERALLY UNIFORM MAGNETIC CHARACTERISTICS IN EVERY DIRECTION COMPRISING GENERATING IN A VACUUM CHAMBER AND IN A MAGNETIC FIELD A PLASMA OF THE GLOW DISCHARGE OF A GAS BETWEEN A NEGATIVELY-CHARGED MAGNETIC RECORDING MEDIUM SUBSTRATE AND A POSITIVELY-CHARGED EVAPORATIVE SOURCE OF A FERROMAGNETIC MATERIAL AND POSITIONING THE SUBSTRATE IN A MAGNETICALLY CONCENTRATED ZONE OF THE PLASMA WHICH IS CONCENTRATED BY THE MAGNETIC FIELD, WHEREBY THE FERROMAGNETIC MATERIAL IS EVAPORATED AND DEPOSITED ON THE MAGNETIC RECORDING MEDIUM SUBSTRATE.
Claim 2
Independent Claim
87 words
A METHOD FOR PRODUCING A MAGNETIC RECORDING MEDIUM BY IONIC-PLATING HAVING GENERALLY UNIFORM MAGNETIC CHARACTERISTICS IN EVERY DIRECTION COMPRISING GENERATING IN A VACUUM CHAMBER AND IN A MAGNETIC FIELD A PLASMA OF THE GLOW DISCHARGE OF A GAS BETWEEN A NEGATIVELY-CHARGED MAGNETIC RECORDING MEDIUM SUBSTRATE AND A POSITIVELY-CHARGED EVAPORATIVE SOURCE OF A FERROMAGNETIC MATERIAL AND POSITIONING THE SUBSTRATE IN A MAGNETICALLY CONCENTRATED ZONE OF THE PLASMA WHICH IS CONCENTRATED BY THE MAGNETIC FIELD, WHEREBY THE FERROMAGNETIC MATERIAL IS EVAPORATED AND DEPOSITED ON THE MAGNETIC RECORDING MEDIUM SUBSTRATE.
Claim 3
Dependent Claim
21 words
The method as claimed in claim 1, wherein the magnetic field has a strength ranging from about 50 to 5000 oe.
Claim 4
Dependent Claim
20 words
The method as claimed in claim 1, wherein the voltage of the glow discharge is about 0.1 to 5.0 kv.
Claim 5
Dependent Claim
18 words
The method as claimed in claim 1, wherein the degree of vacuum is about 0.001 to 0.1 Torr.
Claim 6
Dependent Claim
18 words
The method as claimed in claim 1, wherein the ionic-plating is conducted for about 0.5 to 20 minutes.
Claim 7
Dependent Claim
27 words
The method as claimed in claim 1, wherein the gas is chosen from at least one of the group consisting of nitrogen gas and a noble gas.
Claim 8
Dependent Claim
28 words
The method as claimed in claim 6, wherein said gas is chosen from at least one of the group consisting of helium, neon, argon, krypton, xenon and radon.
Claim 9
Dependent Claim
28 words
The method as claimed in claim 1, wherein the ionic-plating is continued until the thickness of the ferromagnetic thin film ranges from about 0.05 to 1.0 Mu m.
Claim 10
Dependent Claim
48 words
The method as claimed in claim 1, wherein the magnetic material is at least one ferromagnetic substance selected from the group consisting of Fe, Co, Ni, Fe-Co, Fe-Ni, Co-Ni, Fe-Rh, Fe-Cu, Fe-Au, Co-Cu, Co-Au, Co-Y, Co-La, Co-Pr, Co-Gd, Co-Sm, Co-Pt, Ni-Cu, Fe-Co-Ni, Mn-Bi, Mn-Sb, Mn-Al, Ba-ferrite and Sr-ferrite.
Claim 11
Dependent Claim
35 words
The method as claimed in claim 1, wherein the magnetic recording medium substrate is wound around a permanent magnet in the central region between the N-pole and S-pole, said permanent magnet acting as a cathode.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |