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Patent US4156561A successfully refreshed from Google Patents.
US4156561A
Expired / Lapsed
US
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Desk level overhead projector
Assignee: Bell and Howell Co
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Filing: 1966-10-10
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Granted: 1979-05-29
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Expires: 1986-10-10
Abstract
Abstract A first lens system projects an image onto an optical director which converges the light from the image into a second lens system which reprojects the image onto a screen to be viewed by an audience.
Inventors
- 👤 James W. Lucas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:13
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/132; Y; Y10; Y10S; Y10S353/00; Y10S353/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
120 words
A projector for projecting light onto a screen, comprising a first optical projection system for projecting a first image, a second optical projection system positioned and constructed to view said first image and to reproject it onto said screen as a second image which is larger than said first image and adapted to be viewed by an audience, and an optical director system interposed optically between said first and second systems and positioned at approximately the plane of focus of said first image and constructed to direct the light from different portions of said first image primarily along converging paths in a relation concentrating the light more on said second optical system than if said director system were not present.
Claim 2
Dependent Claim
120 words
A projector for projecting light onto a screen, comprising a first optical projection system for projecting a first image, a second optical projection system positioned and constructed to view said first image and to reproject it onto said screen as a second image which is larger than said first image and adapted to be viewed by an audience, and an optical director system interposed optically between said first and second systems and positioned at approximately the plane of focus of said first image and constructed to direct the light from different portions of said first image primarily along converging paths in a relation concentrating the light more on said second optical system than if said director system were not present.
References Cited (Backward Citations)
US3253505A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-05-28 | 1982-11-27 | 1983-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-05-28 | 1986-11-27 | 1987-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-05-28 | 1990-11-27 | 1991-05-29 | $7700.00 | Window Closed / Lapsed |