US3898952A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for production of magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1974-07-25
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Granted: 1975-08-12
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Expires: 1994-07-25
Abstract
Abstract An apparatus for the continuous production of a magnetic recording tape comprising A VACUUM CHAMBER CONTAINING MEANS INCLUDING AN ANODE AND A CATHODE FOR GENERATING A PLASMA OF THE GLOW DISCHARGE OF A GAS THEREBETWEEN, A ROTABLE CYLINDRICAL PERMANENT MAGNET AS THE CATHODE OF THE PLASMA GENERATING MEANS, A TAPE SUBSTRATE SUPPLY ROLL AND A TAPE SUBSTRATE TAKE UP ROLL FOR PASSING A TAPE SUBSTRATE IN CONTACT WITH THE ROTABLE CYLINDRICAL PERMANENT MAGNET AS THE CATHODE OF THE PLASMA GENERATING MEANS AND POSITIONED SUCH THAT THE TAPE CONTACTS THE CYLINDRICAL PERMANENT MAGNETIC WHEREBY THE ROTABLE MAGNET ROTATES AS THE TAPE IS PASSED BY THE SUPPLY ROLL AND THE TAKE UP ROLL AND SUCH THAT THE TAPE PASSES THROUGH A PLASMA ZONE CONCENTRATED BY THE CYLINDRICAL PERMANENT MAGNET, AND MEANS FOR EVAPORATING A FERROMAGNETIC SUBSTANCE AS THE ANODE OF THE PLASMA GENERATING MEANS.
Inventors
- 👤 Ryuji Shirahata
- 👤 Tatsuji Kitamoto
- 👤 Mahito Shimizu
- 👤 Masaaki Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:03
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/14; C; C23; C23C; C23C14/00; C23C14/22; C23C14/24; C23C14/32
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
142 words
An apparatus for the continuous production of a magnetic recording tape comprising a vacuum chamber containing means including an anode and a cathode for generating a plasma of the glow discharge of a gas therebetween, a rotatable cylindrical permanent magnet as the cathode of the plasma generating means, a tape substrate supply roll and a tape substrate take up roll for passing a tape substrate in contact with the rotatable cylindrical permanent magnet as the cathode of the plasma generating means and positioned such that the tape contacts the cylindrical permanent magnet whereby the rotable magnet rotates as the tape is passed by the supply roll and the takE up roll and such that the tape passes through a plasma zone concentrated by the cylindrical permanent magnet, and means for evaporating a ferromagnetic substance as the anode of the plasma generating means.
Claim 2
Independent Claim
142 words
An apparatus for the continuous production of a magnetic recording tape comprising a vacuum chamber containing means including an anode and a cathode for generating a plasma of the glow discharge of a gas therebetween, a rotatable cylindrical permanent magnet as the cathode of the plasma generating means, a tape substrate supply roll and a tape substrate take up roll for passing a tape substrate in contact with the rotatable cylindrical permanent magnet as the cathode of the plasma generating means and positioned such that the tape contacts the cylindrical permanent magnet whereby the rotable magnet rotates as the tape is passed by the supply roll and the takE up roll and such that the tape passes through a plasma zone concentrated by the cylindrical permanent magnet, and means for evaporating a ferromagnetic substance as the anode of the plasma generating means.
Claim 3
Dependent Claim
14 words
The apparatus as claimed in claim 1, wherein said gas is argon or helium.
Claim 4
Dependent Claim
20 words
The apparatus as claimed in claim 1, wherein the strength of the magnetic field is about 50 to 5,000 oersteds.
Claim 5
Dependent Claim
19 words
The apparatus as claimed in claim 1, wherein the voltage of glow discharge is about 0.1 to 5.0 Kv.
Claim 6
Dependent Claim
22 words
The apparatus as claimed in claim 1, wherein the degree of vacuum in the vacuum chamber is about 0.001 to 0.1 Torr.
Claim 7
Dependent Claim
23 words
The apparatus as claimed in claim 1, wherein the thickness of the formed ferromagnetic thin film is about 0.05 to 1.0 Mu m.
Claim 8
Dependent Claim
43 words
The apparatus as claimed in claim 1, wherein said ferromagnetic substance is 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.
References Cited (Backward Citations)
US3477902A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-11 | 1979-02-10 | 1979-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-11 | 1983-02-10 | 1983-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-11 | 1987-02-10 | 1987-08-12 | $7700.00 | Window Closed / Lapsed |