Patent US3944992A successfully refreshed from Google Patents.
US3944992A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto-optical information storage device using photoconductive control element
Assignee: US Philips Corp
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Filing: 1974-11-04
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Granted: 1976-03-16
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Expires: 1994-11-04
Abstract
Abstract The invention relates to a device for magneto-optic memories controlled by light and/or heat in an external magnetic field, in which the magneto-optic material of the memory has a photoconductive layer which can be activated by the control beam and which can be controlled by means of electrodes provided thereon via a current or voltage source.
Inventors
- 👤 Jens-Peter Krumme
- 👤 Bernhard Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:47
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/06; G02; G02F; G02F1/00; G02F1/01; G02F1/09
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
58 words
An information storage device comprising a storage plate of a magnetizable material, means including a light beam for recording and retrieving information in said storage plate, a photoconductive layer on the magneto-optic material of the storage plate, and electrode means on said photoconductive layer, said electrode means being connected to an electrical power source to heat said layer.
Claim 2
Dependent Claim
58 words
An information storage device comprising a storage plate of a magnetizable material, means including a light beam for recording and retrieving information in said storage plate, a photoconductive layer on the magneto-optic material of the storage plate, and electrode means on said photoconductive layer, said electrode means being connected to an electrical power source to heat said layer.
Claim 3
Dependent Claim
22 words
A device as claimed in claim 1, wherein the electrodes are transparent and the photoconductive layer is disposed between the transparent electrodes.
Claim 4
Dependent Claim
20 words
A device as claimed in claim 1, wherein the electrodes are positioned only on one surface of the photoconductive layer.
Claim 5
Dependent Claim
18 words
A device as claimed in claim 1 wherein the magneto-optic material is iron garnet having a domain formation.
Claim 6
Dependent Claim
13 words
A device as claimed in claim 1 wherein the photoconductive layer is transparent.
Claim 7
Dependent Claim
28 words
A device as claimed in claim 1 wherein the photoconductive layer is not transparent and the surface of the magneto-optic material remote from the photoconductive layer is reflecting.
Claim 8
Dependent Claim
23 words
A device as claimed in claim 3 wherein the electrodes are positioned on a surface of the photoconductive layer facing the magneto-optic material.
Claim 9
Dependent Claim
14 words
A device as claimed in claim 1 wherein the photoconductive layer is cadmium sulfide.
Claim 10
Dependent Claim
17 words
A device as claimed in claim 4 wherein said magneto-optic material is a bismuth substituted ferrimagnetic garnet.
Claim 11
Dependent Claim
15 words
A device as claimed in claim 1 wherein said light beam is a laser beam.
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) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |