US2532741A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microphone with opposite electrodes being of varying and constant curvature
Assignee: AT&T Inc
•
Filing: 1947-10-31
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Granted: 1950-12-05
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Expires: 1967-10-31
Abstract
No abstract record available.
Inventors
- 👤 Ralph R Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:16
CPC Classifications
H; H04; H04R; H04R21/00; H04R21/02; H04R21/021
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2014427A
Cited
US2042822A
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US2191992A
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US2225488A
Cited
US2302278A
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US2320433A
Cited
US2429988A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-12-04 | 1954-06-05 | 1954-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-12-04 | 1958-06-05 | 1958-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-12-04 | 1962-06-05 | 1962-12-05 | $7700.00 | Window Closed / Lapsed |