US3801824A
Expired / Lapsed
US
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Computer memory device
Assignee: Multi State Devices Ltd
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Filing: 1973-05-08
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Granted: 1974-04-02
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Expires: 1993-05-08
Abstract
Abstract A computer memory device utilizes the effect of a wide hysteresis loop which certain memory materials can exhibit at a predetermined critical temperature. A high optical transmission or reflection value and a low optical transmission or reflection value, respectively, will thereby be achieved, depending on whether the memory material is heated or cooled to reach this critical temperature. Laser beams of preselected wavelengths and power levels are directed onto this memory material through an optical arrangement to effect the writing or reading functions.
Inventors
- 👤 H Eastwood
- 👤 R Johannes
- 👤 C Griffiths
- 👤 A Gavini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:23
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/004; G11B7/0055; G11B7/00557; G11B7/12
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
140 words
An optical memory device comprising: a substrate with a smooth surface; a film of a memory material coated on at least a portion of said smooth surface, said film of memory material exhibiting a wide hysteresis loop such that, at a same critical temperature, a high optical transmission or reflection value and a low optical transmission or reflection value, respectively, will be achieved depending on whether the film of said memory material is heated or cooled to reach said critical temperature; means for maintaining said substrate with the film of said memory material coated thereon at substantially said critical temperature; optical means and a source of irradiations interacting therewith for impinging upon said film irradiations of preselected wavelengths and power levels; and radiation sensitive means adapted to produce suitable output signals when said irradiations are directed thereonto from said film.
Claim 2
Dependent Claim
140 words
An optical memory device comprising: a substrate with a smooth surface; a film of a memory material coated on at least a portion of said smooth surface, said film of memory material exhibiting a wide hysteresis loop such that, at a same critical temperature, a high optical transmission or reflection value and a low optical transmission or reflection value, respectively, will be achieved depending on whether the film of said memory material is heated or cooled to reach said critical temperature; means for maintaining said substrate with the film of said memory material coated thereon at substantially said critical temperature; optical means and a source of irradiations interacting therewith for impinging upon said film irradiations of preselected wavelengths and power levels; and radiation sensitive means adapted to produce suitable output signals when said irradiations are directed thereonto from said film.
Claim 3
Dependent Claim
117 words
An optical memory device according to claim 1, wherein the source of irradiations is adapted to produce irradiations that will heat said film coated on said substrate at predetermined discrete areas upon which said irradiations impinge, thereby writing dots on said film which become stored at the critical temperature; said source of irradiations also being adapted to produce irradiations that will be blocked by the film when the critical temperature has been reached by cooling, but will pass therethrough when said critical temperature has been reacheD by heating; said irradiations passing through said film will be transmitted onto said radiation sensitive means and thereby produce suitable output signals resulting in reading of data written on said film.
Claim 4
Dependent Claim
119 words
An optical memory device according to claim 1, wherein the source of irradiations is adapted to produce irradiations that will heat said film coated on said substrate at predetermined discrete areas upon which said irradiations impinge, thereby writing dots on said film which will become stored at the critical temperature; said source of irradiations also being adapted to produce irradiations that will be blocked by the film when the critical temperature has been reached by heating, but will be reflected therefrom when said critical temperature has been reached by cooling; said irradiations reflected from said film will be directed to the radiation sensitive means and thereby produce suitable output signals resulting in reading of data written on said film.
Claim 5
Dependent Claim
38 words
An optical memory device according to claim 2, wherein said source of irradiations is adapted to produce, at a predetermined sequence, irradiations of preselected wavelength and power for writing and irradiations of another wavelength and power for reading.
Claim 6
Dependent Claim
38 words
An optical memory device according to claim 3, wherein said source of irradiations is adapted to produce, at a predetermined sequence, irradiations of preselected wavelength and power for writing and irradiations of another wavelength and power for reading.
Claim 7
Dependent Claim
42 words
An optical memory device according to claim 2, wherein said source of irradiations is adapted to produce, at a predetermined sequence, irradiations of preselected wavelength and high power for writing and continuous irradiations of the same wavelength and low power for reading.
Claim 8
Dependent Claim
42 words
An optical memory device according to claim 3, wherein aid source of irradiations is adapted to produce, at a predetermined sequence, irradaitions of preselected wavelength and high power for writing and continuous irradiations of the same wavelength and low power for reading.
Claim 9
Dependent Claim
79 words
An optical memory device according to claim 2, wherein said substrate is made of a transparent material capable of withstanding a temperature of about 400* C and capable of providing the film coated thereon with a wide hysteresis loop such that at a predetermined critical temperature, a high optical transmission value and a low optical transmission value, respectively, will be achieved depending on whether the film of said memory material is heated or cooled to reach said critical temperature.
Claim 10
Dependent Claim
18 words
An optical memory device according to claim 8, wherein said transparent material is fused silica or soda glass.
Claim 11
Dependent Claim
75 words
An optical memory device according to claim 3, wherein said substrate is made of a material capable of withstanding a temperature of about 400* C and capable of providing the film coated thereon with a wide hysteresis loop such that at a same critical temperature a high optical reflection value and a low optical reflection value, respectively, will be achieved depending on whether the said film is heated or cooled to reach said critical temperature.
Claim 12
Dependent Claim
16 words
An optical memory device according to claim 1, wherein said film is a film of VO2.
Claim 13
Dependent Claim
21 words
An optical memory device according to claim 11, wherein said film has a thickness of between 1,000 and 4,000 Angstrom units.
Claim 14
Dependent Claim
70 words
An optical memory device according to claim 1, wherein said means for maintaining said substrate with the film of said memory material coated thereon at the critical temperature comprise an enclosure in which said substrate with said film coated thereon is mounted, means for bringing the temperature within said enclosure to the critical temperature value, and temperature control means for maintaining said temperature within the enclosure at said critical value.
Claim 15
Dependent Claim
70 words
An optical memory device according to claim 11, wherein said means for maintaining said substrate with the film of said memory material Coated thereon at the critical temperature comprise an enclosure in which said substrate with said film coated thereon is mounted, a heater for bringing the temperature within said enclosure to said critical value, and temperature control means for maintaining said temperature within the enclosure at said critical value.
Claim 16
Dependent Claim
40 words
An optical memory device according to claim 1, wherein said optical means comprise a combination of mirrors and lenses for transmitting irradiations from the source thereof and focussing them onto the film of said memory material coated on the substrate.
Claim 17
Dependent Claim
32 words
An optical memory device according to claim 15, wherein between said source of irradiations and said optical means there are interposed means for interrupting the intensity of said irradiations at predetermined intervals.
Claim 18
Dependent Claim
21 words
An optical memory device according to claim 16, wherein said means for interrupting the intensity of irradiations consist of a modulator.
Claim 19
Dependent Claim
29 words
An optical memory device according to claim 1, wherein said optical means are also combined with means for effecting random scanning of said film by the irradiations impinging thereupon.
Claim 20
Dependent Claim
35 words
An optical memory device according to claim 1, further comprising means for producing synchronized and controlled relative movement between said substrate with the film of said memory material coated thereon and said source of irradiations.
Claim 21
Dependent Claim
39 words
An optical memory device according to claim 19, wherein said substrate with the film coated thereon is in the form of a disc and means are provided for rotating said disc at controlled speed and in a synchronized manner.
Claim 22
Dependent Claim
31 words
An optical memory device according to claim 1, wherein said source of irradiations is a laser and said radiation sensitive means comprise a photosensor for light beams produced by said laser.
Claim 23
Dependent Claim
19 words
An optical memory device according to claim 1, further comprising cooling means for cooling the film in predetermined areas.
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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |