Patent US5243590A successfully refreshed from Google Patents.
US5243590A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical disc
Assignee: Sony Corp
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Filing: 1991-10-28
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Granted: 1993-09-07
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Expires: 2011-10-28
Abstract
Abstract The present invention is concerned with an optical disc in which a layer of a material undergoing partial phase transitions within a scanning light spot of a readout light so as to be changed in this manner in its optical constants is formed on a base plate, on which phase pits are formed in advance in accordance with information signals, and in which the layer of the material is reset to its initial state, even if the pit period is less than the limit of diffraction, satisfactory reproduction free of crosstalks may be achieved to enable high density recording.
Inventors
- 👤 Katsuhisa Aratani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:29
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/242; G11B7/243; G11B7/004; G11B7/0055; G11B7/00557; G11B7/252; G11B7/257; G11B2007/24302; G11B2007/24314; G11B2007/24316
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
82 words
AN optical disc comprising a layer of a material formed on a transparent base plate on which phase pits are formed in advance, said material having its optical constants such as absorption coefficient and refractive index changed temporarily by phase transitions, characterized in that said layer of the material undergoes partial phase transitions within a scanning light spot of a readout light when irradiated with the readout light, said layer of the material reverting to an initial state after termination of reading.
Claim 2
Dependent Claim
82 words
AN optical disc comprising a layer of a material formed on a transparent base plate on which phase pits are formed in advance, said material having its optical constants such as absorption coefficient and refractive index changed temporarily by phase transitions, characterized in that said layer of the material undergoes partial phase transitions within a scanning light spot of a readout light when irradiated with the readout light, said layer of the material reverting to an initial state after termination of reading.
Claim 3
Dependent Claim
49 words
The optical disc as claimed in claim 1 characterized in that the initial state of said layer of the material temporarily is the crystalline state and said layer of the material becomes partially amorphous as a result of temperature distribution within the scanning light spot of the readout light.
Claim 4
Dependent Claim
22 words
The optical disc as claimed in claim 1 characterized in that the material of said layer of the material is a chalcogenide.
Claim 5
Dependent Claim
21 words
The optical disc as claimed in claim 1 characterized in that the material of said layer of the material is SbTe.
Claim 6
Dependent Claim
33 words
The optical disc as claimed in claim 1 characterized in that a first dielectric layer, the layer of the material and a second dielectric layer are sequentially formed on said transparent base plate.
Claim 7
Dependent Claim
36 words
The optical disc as claimed in claim 1 characterized in that a first dielectric layer, the layer of the material, a second dielectric layer and a reflective layer are sequentially formed on said transparent base plate.
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) | 1996-09-06 | 1997-03-08 | 1997-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-06 | 2001-03-08 | 2001-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-06 | 2005-03-08 | 2005-09-07 | $7700.00 | Window Closed / Lapsed |