US4985306A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Base plate for recording disc and a method for its manufacture
Assignee: Individual
•
Filing: 1990-01-09
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Granted: 1991-01-15
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Expires: 2010-01-09
Abstract
Abstract Herein disclosed is a method for manufacturing a base plate for a recording disc, which comprises steps of: subjecting a base plate containing therein SiO 2 -Li 2 O-Al 2 O 3 series crystallized glass to crystallizing treatment; then polishing the surface of said base plate; and thereafter subjecting the base plate to etching treatment with use of etching agents having different rates of etching between the crystallized layer and the amorphous layer, and also a base plate for a recording disc which is produced by the method as described above.
Inventors
- 👤 Toshinori Morizane
- 👤 Tadao Tokushima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; C; C03; C03C; C03C15/00; G11B5/84; G11B5/8404; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24479
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
68 words
A method for manufacturing a base plate for a recording disc, which comprises steps of: subjecting a base plate containing therein SiO 2 -Li 2 O-Al 2 O 3 series crystallized glass to crystallizing treatment; polishing the surface of said base plate; and thereafter subjecting said base plate to etching treatment with use of etchants having different rates of etching between the crystallized layer and the amorphous layer.
Claim 2
Independent Claim
68 words
A method for manufacturing a base plate for a recording disc, which comprises steps of: subjecting a base plate containing therein SiO 2 -Li 2 O-Al 2 O 3 series crystallized glass to crystallizing treatment; polishing the surface of said base plate; and thereafter subjecting said base plate to etching treatment with use of etchants having different rates of etching between the crystallized layer and the amorphous layer.
Claim 3
Dependent Claim
64 words
A base plate for a recording disc obtained by the method of subjecting a base plate containing therein SiO 2 -Li 2 O-Al 2 O 3 series crystallized glass to crystallizing treatment; polishing the surface of said base plate; thereafter subjecting said base plate to etching treatment with use of etchants having different rates of etching between the crystallized layer and the amorphous layer.
Claim 4
Dependent Claim
64 words
A base plate for a recording disc obtained by the method of subjecting a base plate containing therein SiO 2 -Li 2 O-Al 2 O 3 series crystallized glass to crystallizing treatment; polishing the surface of said base plate; thereafter subjecting said base plate to etching treatment with use of etchants having different rates of etching between the crystallized layer and the amorphous layer.
Claim 5
Dependent Claim
20 words
A base plate for a recording disc as set forth in claim 2, wherein said etchant contains therein hydrogen peroxide.
Claim 6
Dependent Claim
37 words
A base plate for a recording disc as set forth in claim 2, wherein depth of convexities and concavities on the surface of said base plate is in a range of from 50 Å to 2,000 Å.
Claim 7
Dependent Claim
29 words
A base plate for a recording disc as set forth in claim 2 or 3, wherein the surface of said base plate is coated with a rigid coating material.
Claim 8
Dependent Claim
20 words
A removing agent for a magnetic metal thin film which consists essentially of ammon ceric sulfate, perchloric acid, and water.
Claim 9
Dependent Claim
20 words
A removing agent for a magnetic metal thin film which consists essentially of ammon ceric sulfate, perchloric acid, and water.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-14 | 1994-07-16 | 1995-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-14 | 1998-07-16 | 1999-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-14 | 2002-07-16 | 2003-01-15 | $7700.00 | Window Closed / Lapsed |