US2642947A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic device with an inverted horn having a throat vented to the atmosphere
Assignee: Individual
•
Filing: 1948-12-02
•
Granted: 1953-06-23
•
Expires: 1968-12-02
Abstract
No abstract record available.
Inventors
- 👤 Stephen L Heidrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:10
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/20; H04R1/22; H04R1/30; H04R1/28; H04R1/2807; H04R1/2861; H04R1/2865
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1759614A
Cited
US1943499A
Cited
US1843524A
Cited
US1891968A
Cited
US2160283A
Cited
GB484704A
Cited
US2224919A
Cited
US2167625A
Cited
US2310243A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1956-06-22 | 1956-12-22 | 1957-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-06-22 | 1960-12-22 | 1961-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-06-22 | 1964-12-22 | 1965-06-23 | $7700.00 | Window Closed / Lapsed |