US4422904A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming video discs
Assignee: Discovision Associates
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Filing: 1982-09-30
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Granted: 1983-12-27
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Expires: 2002-09-30
Abstract
Abstract An improved process for making video discs, which enables the molding of replicas having substantially higher signal-to-noise ratios during playback. One aspect of the invention extends the duration of a photoresist development process to yield developed recording masters having spaced information-bearing pits with unexpectedly steeper sidewalls. Another aspect of the invention forms metallic stampers using an initial vapor deposition step carried out in an extremely low pressure of about 1×10 -6 torr, to reduce oxidation and thereby improve conformity between the photoresist geometry and the stamper geometry.
Inventors
- 👤 Richard L. Wilkinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:01
CPC Classifications
G; G11; G11B; G11B23/00; G11B23/0057; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/253; G11B7/2531
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
144 words
A method for forming a stamper for use in molding video disc replicas, comprising steps of: forming a disc-shaped master recording that includes a glass substrate and a thin recording layer, an information signal being recorded in the recording layer in a sequence of spaced pits arranged in a plurality of substantially circular and concentric recording tracks; vapor depositing a first thin, uniform, metallic film on the recording layer of the master recording, the vapor depositing occurring in a pressure of about 1×10 -6 torr or less; electroplating a second thin, uniform, metallic film onto the first film, the first and second films together forming an integral, metallic layer; separating the metallic layer from the underlying master recording; and removing residual recording layer material from the undersurface of the separated metallic layer, to form a stamper suitable for use in molding video disc replicas.
Claim 2
Independent Claim
144 words
A method for forming a stamper for use in molding video disc replicas, comprising steps of: forming a disc-shaped master recording that includes a glass substrate and a thin recording layer, an information signal being recorded in the recording layer in a sequence of spaced pits arranged in a plurality of substantially circular and concentric recording tracks; vapor depositing a first thin, uniform, metallic film on the recording layer of the master recording, the vapor depositing occurring in a pressure of about 1×10 -6 torr or less; electroplating a second thin, uniform, metallic film onto the first film, the first and second films together forming an integral, metallic layer; separating the metallic layer from the underlying master recording; and removing residual recording layer material from the undersurface of the separated metallic layer, to form a stamper suitable for use in molding video disc replicas.
References Cited (Backward Citations)
US2530842A
Cited
US4211617A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |