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US3576546A
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Photochromic-photoconductive memory
Assignee: RCA Corp
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Filing: 1968-06-03
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Granted: 1971-04-27
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Expires: 1988-06-03
Abstract
Abstract Memories employing a material whose photoconductivity can be altered by electromagnetic radiation such as light and which store their new value of photoconductivity upon removal of the light. Information is written into the memories optically and is read out of the memories by optical selection and electrical signal-sensing.
Inventors
- 👤 Philip M Heyman
- 👤 Zoltan J Kiss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:07
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/041
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
132 words
A memory comprising, in combination: a layer of photochromic-photoconductive material; means for selectively illuminating subareas of the medium by light in a frequency range which causes the photoconductivity of these subareas to change and to remain at a new value after removal of said light; means for charging said medium after said selective illumination thereof; and means for reading the information stored in said layer comprising means for illuminating said subareas by light in a frequency range at which the medium exhibits its new value of photoconductivity, means for recharging said medium after the application thereto of said light in said frequency range at which the medium exhibits its new value of photoconductivity, and means for sensing the relative amounts of charge deposited at the respective subareas in response to said recharging.
Claim 2
Dependent Claim
132 words
A memory comprising, in combination: a layer of photochromic-photoconductive material; means for selectively illuminating subareas of the medium by light in a frequency range which causes the photoconductivity of these subareas to change and to remain at a new value after removal of said light; means for charging said medium after said selective illumination thereof; and means for reading the information stored in said layer comprising means for illuminating said subareas by light in a frequency range at which the medium exhibits its new value of photoconductivity, means for recharging said medium after the application thereto of said light in said frequency range at which the medium exhibits its new value of photoconductivity, and means for sensing the relative amounts of charge deposited at the respective subareas in response to said recharging.
Claim 3
Dependent Claim
39 words
A memory as set forth in claim 1, wherein said means for charging and said means for recharging comprises: means producing a beam of electrons; and means for directing said beam of electrons at said layer of photochromic-photoconductive material.
Claim 4
Dependent Claim
35 words
A memory as set forth in claim 2, wherein said means for directing said beam of electrons at said medium comprises means for raster scanning said beam of electrons over the surface of said medium.
Claim 5
Dependent Claim
51 words
A memory as set forth in claim 2, wherein said photochromic-photoconductive material comprises the face of a cathode-ray tube, said means producing a beam of electrons comprising an electron gun within said cathode-ray tube, and further including a transparent conductive layer on said face forming the outer layer of said face.
Claim 6
Dependent Claim
17 words
A memory as set forth in claim 1, wherein said medium is a rare earth-doped calcium fluoride.
References Cited (Backward Citations)
US2985757A
Cited
US3341825A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-26 | 1974-10-26 | 1975-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-26 | 1978-10-26 | 1979-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-26 | 1982-10-26 | 1983-04-27 | $7700.00 | Window Closed / Lapsed |