US3444955A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Directional microphone with substantially frequency-independent directional characteristics
Assignee: Sennheiser Electronic GmbH and Co KG
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Filing: 1967-11-08
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Granted: 1969-05-20
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Expires: 1987-11-08
Abstract
No abstract record available.
Inventors
- 👤 Otto Hoffmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:41
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/32; H04R1/34; H04R1/342
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-05-19 | 1972-11-18 | 1973-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-05-19 | 1976-11-18 | 1977-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-05-19 | 1980-11-18 | 1981-05-20 | $7700.00 | Window Closed / Lapsed |