Patent US2831981A successfully refreshed from Google Patents.
US2831981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo-electric relay apparatus
Assignee: British Thomson Houston Co Ltd
•
Filing: 1955-04-25
•
Granted: 1958-04-22
•
Expires: 1975-04-25
Abstract
No abstract record available.
Inventors
- 👤 Watts Bernard Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:51
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H03F3/08; H05; H05B; H05B47/00; H05B47/10; H05B47/105; H05B47/11; H10; H10D; H10D99/00; H10F; H10F99/00; Y; Y02; Y02B; Y02B20/00; Y02B20/40
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US2425250A
Cited
US2514405A
Cited
US2592683A
Cited
US2675509A
Cited
US2686279A
Cited
US2644852A
Cited
US2718613A
Cited
US2742550A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-04-21 | 1961-10-21 | 1962-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-04-21 | 1965-10-21 | 1966-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-04-21 | 1969-10-21 | 1970-04-22 | $7700.00 | Window Closed / Lapsed |