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US2807674A
Expired / Lapsed
US
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Stereophonic sound system and method
Assignee: AMPEX ELECTRIC Corp
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Filing: 1953-06-29
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Granted: 1957-09-24
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Expires: 1973-06-29
Abstract
No abstract record available.
Inventors
- 👤 Carl H Becker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:23
CPC Classifications
H; H04; H04S; H04S3/00; H04R; H04R5/00; H04R5/027
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) | 1960-09-23 | 1961-03-25 | 1961-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-09-23 | 1965-03-25 | 1965-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-09-23 | 1969-03-25 | 1969-09-24 | $7700.00 | Window Closed / Lapsed |