Patent US2953643A successfully refreshed from Google Patents.
US2953643A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inverted speech privacy using irregular inverting wave form
Assignee: AT&T Inc
•
Filing: 1945-05-10
•
Granted: 1960-09-20
•
Expires: 1965-05-10
Abstract
No abstract record available.
Inventors
- 👤 Jr Walter Koenig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:07
CPC Classifications
H; H04; H04K; H04K1/00; H04K1/04
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US1545270A
Cited
US1522044A
Cited
US1743710A
Cited
US2301455A
Cited
US2406841A
Cited
US2406024A
Cited
US2425616A
Cited
US2401403A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-09-20 | 1964-03-21 | 1964-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-09-20 | 1968-03-21 | 1968-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-09-20 | 1972-03-21 | 1972-09-20 | $7700.00 | Window Closed / Lapsed |