US4745031A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
•
Filing: 1985-12-26
•
Granted: 1988-05-17
•
Expires: 2005-12-26
Abstract
Abstract In a magnetic recording medium of the hard disk type comprising a rigid substrate and a magnetic layer formed thereon, the substrate is plasma treated at frequencies in the range of 10 to 200 kHz in an inorganic gas containing O; N and H; and N, H and O.
Inventors
- 👤 Masatoshi Nakayama
- 👤 Haruyuki Morita
- 👤 Yuichi Kubota
- 👤 Keiko Tsuchiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/62; G11B5/73; G11B5/7368; G11B5/739; G11B5/73911; G11B5/73917; G11B5/73921; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12931; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
89 words
A magnetic recording medium, comprising: a rigid substrate of a material selected from the group consisting of metal, hard glass and ceramics which has been plasma treated at a frequency of 10 kHz to 200 kHz in an atmosphere consisting essentially of an inorganic gas; and a magnetic layer formed on said substrate, wherein saids inorganic gas is a member selected from the group consisting of N 2 , H 2 , NH 3 , O 2 , O 3 , H 2 O, NO x and mixtures thereof.
Claim 2
Dependent Claim
89 words
A magnetic recording medium, comprising: a rigid substrate of a material selected from the group consisting of metal, hard glass and ceramics which has been plasma treated at a frequency of 10 kHz to 200 kHz in an atmosphere consisting essentially of an inorganic gas; and a magnetic layer formed on said substrate, wherein saids inorganic gas is a member selected from the group consisting of N 2 , H 2 , NH 3 , O 2 , O 3 , H 2 O, NO x and mixtures thereof.
Claim 3
Dependent Claim
21 words
The magnetic recording medium of claim 1, which further comprises an undercoat layer positioned between said substrate and said magnetic layer.
Claim 4
Dependent Claim
22 words
The magnetic recording medium of claim 2, wherein said undercoat layer is formed of an alloy of aluminum, copper, titanium or chromium.
Claim 5
Dependent Claim
31 words
The magnetic recording medium of claim 1, wherein the plasma treatment of said rigid substrate occurs at a flow rate of inorganic gas of from 1 to 250 ml per minute.
Claim 6
Dependent Claim
24 words
The magnetic recording medium of claim 1, wherein the pressure within the plasma generation vessel is within the range of 0.01 to 10 torr.
Claim 7
Dependent Claim
23 words
The magnetic recording medium of claim 1, wherein the inorganic gas contains O 2 in an amount of at least 5% by volume.
Claim 8
Dependent Claim
34 words
The magnetic recording medium of claim 1, wherein said inorganic gas contains from 5 to 80 at % N from 5 to 80 at % H and from 0 to 50 at % O.
Claim 9
Dependent Claim
15 words
The magnetic recording medium of claim 1, wherein said rigid substrate is a metal substrate.
References Cited (Backward Citations)
US4250225A
Cited
US4419404A
Cited
US4551778A
Cited
US4419381A
Cited
US4548864A
Cited
US4582746A
Cited
US4565734A
Cited
US4575475A
Cited
US4526806A
Cited
US4543268A
Cited
US4594262A
Cited
US4699847A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |