Patent US1675879A successfully refreshed from Google Patents.
US1675879A
Expired / Lapsed
US
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System for producing and transmitting high-frequency sound energy
Assignee: AT&T Inc
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Filing: 1919-11-21
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Granted: 1928-07-03
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Expires: 1939-11-21
Abstract
No abstract record available.
Inventors
- 👤 Irving B Crandall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:20
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/0207; B06B1/0223; B06B1/0269; B06B1/0276; B06B2201/00; B06B2201/50; B06B2201/51; B06B2201/70
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1931-07-03 | 1932-01-02 | 1932-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1935-07-03 | 1936-01-02 | 1936-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1939-07-03 | 1940-01-02 | 1940-07-03 | $7700.00 | Window Closed / Lapsed |