Patent US3515820A successfully refreshed from Google Patents.
US3515820A
Expired / Lapsed
US
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Feature equipment for use in electronic switching telephone systems
Assignee: TDK Micronas GmbH
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Filing: 1966-06-06
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Granted: 1970-06-02
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Expires: 1986-06-06
Abstract
No abstract record available.
Inventors
- 👤 John Bereznak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:13
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; H04M3/32; H04M3/323; H04Q; H04Q1/00; H04Q1/18; H04Q1/20; H04Q1/22
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2991335A
Cited
US3047680A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-06-01 | 1973-12-01 | 1974-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-06-01 | 1977-12-01 | 1978-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-06-01 | 1981-12-01 | 1982-06-02 | $7700.00 | Window Closed / Lapsed |