US3539798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shadowless projection systems
Assignee: Individual
•
Filing: 1967-07-18
•
Granted: 1970-11-10
•
Expires: 1987-07-18
Abstract
No abstract record available.
Inventors
- 👤 Donald M Perry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:25
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/14; G03B21/20
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1260439A
Cited
US1750319A
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US2282167A
Cited
US2273447A
Cited
US2338078A
Cited
US2478336A
Cited
US2764058A
Cited
US3395272A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-11-09 | 1974-05-11 | 1974-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-11-09 | 1978-05-11 | 1978-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-11-09 | 1982-05-11 | 1982-11-10 | $7700.00 | Window Closed / Lapsed |