Patent US2500638A successfully refreshed from Google Patents.
US2500638A
Expired / Lapsed
US
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Aid for the blind
Assignee: AT&T Inc
•
Filing: 1946-04-26
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Granted: 1950-03-14
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Expires: 1966-04-26
Abstract
No abstract record available.
Inventors
- 👤 Edwin A Krauth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:05
CPC Classifications
G; G01; G01S; G01S15/00; G01S15/02; G01S15/06; G01S15/08; G01S15/10; G01S15/102; G01S15/105; Y; Y10; Y10S; Y10S367/00; Y10S367/91
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1718422A
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US1692119A
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US2098266A
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US1973673A
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US2083344A
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US2144843A
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US2338395A
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US2371988A
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US2405134A
Cited
US2395368A
Cited
US2428424A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-03-13 | 1953-09-12 | 1954-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-03-13 | 1957-09-12 | 1958-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-03-13 | 1961-09-12 | 1962-03-14 | $7700.00 | Window Closed / Lapsed |