US2551447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrodynamic speaker
Assignee: OPERADIO Manufacturing CO
•
Filing: 1948-05-20
•
Granted: 1951-05-01
•
Expires: 1968-05-20
Abstract
No abstract record available.
Inventors
- 👤 John F Marquis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:19
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/02; H04R9/025; H04R9/06; H04R2209/00; H04R2209/022
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1995080A
Cited
US1991738A
Cited
DE692963C
Cited
US2400662A
Cited
GB558709A
Cited
US2395166A
Cited
US2423037A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-04-30 | 1954-10-30 | 1955-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-04-30 | 1958-10-30 | 1959-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-04-30 | 1962-10-30 | 1963-05-01 | $7700.00 | Window Closed / Lapsed |