Patent US2933145A successfully refreshed from Google Patents.
US2933145A
Expired / Lapsed
US
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Headphone device
Assignee: Dictaphone Corp
•
Filing: 1958-02-26
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Granted: 1960-04-19
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Expires: 1978-02-26
Abstract
No abstract record available.
Inventors
- 👤 Mattia Alfred L Di
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:20
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/10; H04R1/1016; H04R1/20; H04R1/32; H04R1/34; H04R1/345; H04R5/00; H04R5/033; H04R5/0335
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2220208A
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US2363686A
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US2389868A
Cited
US2485405A
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US2498960A
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US2717932A
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US2780681A
Cited
US2827514A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-04-19 | 1963-10-19 | 1964-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-04-19 | 1967-10-19 | 1968-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-04-19 | 1971-10-19 | 1972-04-19 | $7700.00 | Window Closed / Lapsed |