Patent US3926520A successfully refreshed from Google Patents.
US3926520A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for electronic adjustment of effective contrast ratio in photographic reproduction
Assignee: United States Department of the Air Force
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Filing: 1974-07-12
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Granted: 1975-12-16
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Expires: 1994-07-12
Abstract
Abstract A system for controlling the contrast of light intensities falling upon a photosensitive surface after being transmitted through a transparency. Polarized light passes the transparency to a partially silvered mirror which reflects a portion of the light to an array of photosensors and also transmits a portion of the light to a ferroelectric plate. The photosensitive array and the ferroelectric plate are simultaneously scanned. At each scanning position of the photosensitive surface an electrical signal is caused to be applied to the corresponding scanned position of the ferroelectric plate, the intensity being controlled by a variable amplifier. The controlled light passing from the ferroelectric plate is transmitted through a polarizer to the photosensitive surface.
Inventors
- 👤 Irving Kaufman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:35
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/725
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
A system for controlling contrast of light passing through a transparency to a photosensitive surface comprising: a. a source of polarized light directed to the transparency; b. a plate of transparent ferroelectric material segmented into a multiplicity of elements positioned to receive the light emitted through the transparency; c. a polarizer interposed between the transparent ferroelectric material and the photosensitive surface said polarizer being adapted to intercept the light passing through the transparent ferroelectric material; d. a plane surface partially reflective and partially transparent positioned between the transparency and the ferroelectric material; e. an array of photosensors aligned to intercept the reflective light from the plane surface, the electrical output of the array being fed to the elements of the ferroelectric material; and f. a scan generator connected between the photosensitive array and the ferroelectric material for simultaneously scanning the output of the photosensors and the corresponding elements of the plate of ferroelectric material.
Claim 2
Independent Claim
154 words
A system for controlling contrast of light passing through a transparency to a photosensitive surface comprising: a. a source of polarized light directed to the transparency; b. a plate of transparent ferroelectric material segmented into a multiplicity of elements positioned to receive the light emitted through the transparency; c. a polarizer interposed between the transparent ferroelectric material and the photosensitive surface said polarizer being adapted to intercept the light passing through the transparent ferroelectric material; d. a plane surface partially reflective and partially transparent positioned between the transparency and the ferroelectric material; e. an array of photosensors aligned to intercept the reflective light from the plane surface, the electrical output of the array being fed to the elements of the ferroelectric material; and f. a scan generator connected between the photosensitive array and the ferroelectric material for simultaneously scanning the output of the photosensors and the corresponding elements of the plate of ferroelectric material.
Claim 3
Dependent Claim
26 words
A system for controlling contrast of light according to claim 1 wherein the plate of ferroelectric material is a composition of lead, lanthanum, zirconium and titanate.
Claim 4
Dependent Claim
19 words
A system for controlling contrast of light according to claim 2 wherein the array of photosensors is a ridicon.
Claim 5
Dependent Claim
30 words
A system for controlling contrast of light according to claim 2 wherein the scan generator for the plate of ferroelectric material is a shift register having a multiplicity of stages.
Claim 6
Dependent Claim
35 words
A system for controlling contrast of light according to claim 3 which further comprises an amplifier having a gain control the amplifier being interposed between the array of photosensors and the plate of ferroelectric material.
Claim 7
Dependent Claim
28 words
A system for controlling contrast of light according to claim 4 which further comprises a condenser lens interposed between the source of polarized light and the photosensitive surface.
Claim 8
Dependent Claim
28 words
A system for controlling contrast of light according to claim 5 which further comprises a zero setting control interposed between the amplifier and the plate of ferroelectric material.
Claim 9
Dependent Claim
20 words
A system for controlling contrast of light according to claim 7 wherein the plane surface is a partially silvered mirror.
Claim 10
Dependent Claim
40 words
A system for controlling contrast of light according to claim 8 which further comprises a multiplicity of transparent electrodes connecting each of the elements of the plate of ferroelectric material to one each of the stages of the shift register.
References Cited (Backward Citations)
US3521954A
Cited
US3574458A
Cited
US3598471A
Cited
US3566130A
Cited
US3722998A
Cited
US3680956A
Cited
US3758207A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |