US3905686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Three element projection lens
Assignee: Eastman Kodak Co
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Filing: 1974-10-18
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Granted: 1975-09-16
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Expires: 1994-10-18
Abstract
Abstract A three element photographic projection lens having a front positive biconvex element, a middle negative biconcave element and a rear positive biconvex element. The first and second elements are formed of inexpensive plastic materials. The use of aspheric surfaces on the middle negative element helps in aberration correction. The lens is characterized by improved optical performance at a relative aperture of f/1.80.
Inventors
- 👤 Paul Lewis Ruben
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:51
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/12; G02B9/14; G02B9/16; G02B13/00; G02B13/18
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
42 words
A three element lens comprising a front positive element, a middle negative element and a rear positive element, said middle element having two aspheric surfaces and wherein said lens has a focal length of 30.00mm when constructed according to the following parameters:
Claim 2
Dependent Claim
42 words
A three element lens comprising a front positive element, a middle negative element and a rear positive element, said middle element having two aspheric surfaces and wherein said lens has a focal length of 30.00mm when constructed according to the following parameters:
Claim 3
Dependent Claim
42 words
A three element lens comprising a front positive element, a middle negative element and a rear positive element, said middle element having two aspheric surfaces and wherein said lens has a focal length of 14.00mm when constructed according to the following parameters:
Claim 4
Dependent Claim
42 words
A three element lens comprising a front positive element, a middle negative element and a rear positive element, said middle element having two aspheric surfaces and wherein said lens has a focal length of 14.00mm when constructed according to the following parameters:
References Cited (Backward Citations)
US3762801A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |