Patent US3893758A successfully refreshed from Google Patents.
US3893758A
Expired / Lapsed
US
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Device for projecting pictures on a screen
Assignee: US Philips Corp
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Filing: 1974-04-18
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Granted: 1975-07-08
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Expires: 1994-04-18
Abstract
Abstract A device for projecting pictures on a screen comprising an electro-optical plate the birefringence of which is controlled by means of an electric charge pattern. In order to prevent that the phase shift of the polarized light is influenced in an undesired manner by the projection objective, namely as a result of temperature influences, the projection objective consists of two parts. The first part is situated between the polarizer/analyser and the electro-optical plate, experiences little influence of temperature variations and determines the power of the objective. The second part is situated between the polarizer/analyser and the screen and mainly corrects for the optical errors of the objective.
Inventors
- 👤 Jean Jacques Hunzinger
- 👤 Claude Hily
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:03
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; G; G02; G02B; G02B27/00; G02B27/10; G02B27/1006; G02B27/102; G02B27/1026; G02B27/14; G02B27/145; G02F; G02F1/00; G02F1/01; G02F1/03; G02F1/0333; H04N5/00; H04N5/74
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
100 words
A device for projecting pictures on a screen comprising: a light source, a polarizer/analyzer, a birefringent optical relay, a collimator for collimating the light of the light source on said optical relay, said collimator comprising a first projection objective element, the birefringence of said optical relay being controlled by an electric charge pattern, said first objective element being situated between the polarizer/analyzer and the optical relay, and a second objective element situated between the polarizer/analyzer and the screen and correcting for optical errors of the first projection objective element, said first objective element determining the power of the projection device.
Claim 2
Independent Claim
100 words
A device for projecting pictures on a screen comprising: a light source, a polarizer/analyzer, a birefringent optical relay, a collimator for collimating the light of the light source on said optical relay, said collimator comprising a first projection objective element, the birefringence of said optical relay being controlled by an electric charge pattern, said first objective element being situated between the polarizer/analyzer and the optical relay, and a second objective element situated between the polarizer/analyzer and the screen and correcting for optical errors of the first projection objective element, said first objective element determining the power of the projection device.
Claim 3
Dependent Claim
40 words
A device as claimed in claim 1, wherein the first objective element comprises a plurality of components, all the components of the first projection objective element being manufactured from the same optical material having a small coefficient of thermal expansion.
Claim 4
Dependent Claim
18 words
A device as claimed in claim 2, wherein the first projection objective element is manufactured from silicon oxide.
Claim 5
Dependent Claim
35 words
A device as claimed in claim 1 for displaying colored pictures and comprising three optical relays each for displaying one primary colour, wherein the second projection objective element is common to the three primary colors.
References Cited (Backward Citations)
US2303906A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |