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US4832456A
Expired / Lapsed
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Liquid crystal disc memory with circular grooves for auto-focusing of write-in beam
Assignee: Semiconductor Energy Laboratory Co Ltd
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Filing: 1987-02-20
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Granted: 1989-05-23
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Expires: 2007-02-20
Abstract
Abstract An improved optical memory disc is disclosed which has a liquid crystal layer on which information is written by applying electric field. The liquid crystal layer is sectioned into a plurality of concentric tracks by concentric grooves. When information is written or read, an auto-tracking method can implemented by aid of the grooves.
Inventors
- 👤 Shunpei Yamazaki
- 👤 Takeshi Mizunuma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:22
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B13/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
174 words
A liquid crystal non-volatile disc memory comprising: a pair of circular substrates at least one of which is transparent; a ferroelectric liquid crystal layer disposed between said substrates; a plurality of circular grooves by which memory domains are sectioned in the radial direction of said substrates and which aid the molecules of said liquid crystal layer to be aligned in the circumferential direction, and writing means for writing information into said liquid crystal layer in terms of the two states of (a) the anisotropic absorption in the circumferential direction and (b) the anisotropic absorption in the direction forming double the tilted angle of the liquid crystal, the writing means including means for imposing on the liquid crystal layer an electric field in either direction normal to the liquid crystal layer to change the two states; wherein the circular regions between adjacent grooves constitute tracks for writing on which information is written in terms of said optical characteristics and where the grooves constitute auto-focus tracks to maintain the writing on the circular regions for writing.
Claim 2
Dependent Claim
174 words
A liquid crystal non-volatile disc memory comprising: a pair of circular substrates at least one of which is transparent; a ferroelectric liquid crystal layer disposed between said substrates; a plurality of circular grooves by which memory domains are sectioned in the radial direction of said substrates and which aid the molecules of said liquid crystal layer to be aligned in the circumferential direction, and writing means for writing information into said liquid crystal layer in terms of the two states of (a) the anisotropic absorption in the circumferential direction and (b) the anisotropic absorption in the direction forming double the tilted angle of the liquid crystal, the writing means including means for imposing on the liquid crystal layer an electric field in either direction normal to the liquid crystal layer to change the two states; wherein the circular regions between adjacent grooves constitute tracks for writing on which information is written in terms of said optical characteristics and where the grooves constitute auto-focus tracks to maintain the writing on the circular regions for writing.
Claim 3
Dependent Claim
173 words
A liquid crystal non-volatile disc memory comprising: a pair of circular substrates at least one of which is transparent; a ferroelectric liquid crystal layer disposed between said substrates; a plurality of circular grooves by which memory domains are sectioned in the radial direction of said substrates and which aid the molecules of said liquid crystal layer to be aligned in the circumferential direction, and writing means for writing information into said liquid crystal layer in terms of the two states of (a) the anisotropic absorption in the circumferential direction and (b) the anisotropic absorption in the direction forming double the tilted angle of the liquid crystal, the writing means including means for imposing on the liquid crystal layer an electric field in either direction normal to the liquid crystal layer to change the two states; wherein said grooves constitute tracks for writing on which information is written in terms of said optical characteristics and where the circular regions between adjacent grooves constitute auto-focus tracks to maintain the writing on the tracks for writing.
Claim 4
Dependent Claim
173 words
A liquid crystal non-volatile disc memory comprising: a pair of circular substrates at least one of which is transparent; a ferroelectric liquid crystal layer disposed between said substrates; a plurality of circular grooves by which memory domains are sectioned in the radial direction of said substrates and which aid the molecules of said liquid crystal layer to be aligned in the circumferential direction, and writing means for writing information into said liquid crystal layer in terms of the two states of (a) the anisotropic absorption in the circumferential direction and (b) the anisotropic absorption in the direction forming double the tilted angle of the liquid crystal, the writing means including means for imposing on the liquid crystal layer an electric field in either direction normal to the liquid crystal layer to change the two states; wherein said grooves constitute tracks for writing on which information is written in terms of said optical characteristics and where the circular regions between adjacent grooves constitute auto-focus tracks to maintain the writing on the tracks for writing.
Claim 5
Dependent Claim
15 words
A memory of claims 1 or 2 wherein said grooves are formed on concentric circles.
Claim 6
Dependent Claim
15 words
A memory of claims 1 or 2 wherein said grooves interconnect to make a spiral.
Claim 7
Dependent Claim
32 words
A memory of claims 1 or 2 wherein said ferroelectric liquid crystal layer includes a ferroelectric layer adjacent to a liquid crystal where the ferroelectric layer is subjected to said electric field.
Claim 8
Dependent Claim
46 words
A memory of claims 1 or 2 including means including a charge storage region and an insulator which allows carriers to pass therethrough into said storage region only when said external electric field is applied and blocks escape of the carriers stored in said storage region.
Claim 9
Dependent Claim
19 words
A memory of claim 6 wherein said storage region is made of silicon nitride heavily doped with dangling bonds.
Claim 10
Dependent Claim
13 words
A memory of claim 6 wherein said storage region is made of semiconductor.
Claim 11
Dependent Claim
14 words
A memory of claim 8 wherein said semiconductor layer is heavily doped with impurity.
Claim 12
Dependent Claim
21 words
A memory of claim 8 wherein said storage region is provided in the form of clusters of the storage region material.
Claim 13
Dependent Claim
17 words
A memory of claims 1 or 2 further comprising a pair of electrodes provided on said substrates.
Claim 14
Dependent Claim
24 words
A memory of claim 11 integrated by a jig having inner terminals in contact with said electrodes and external pads connected with said terminals.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-22 | 1992-11-21 | 1993-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-22 | 1996-11-21 | 1997-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-22 | 2000-11-21 | 2001-05-23 | $7700.00 | Window Closed / Lapsed |