Patent US2674657A successfully refreshed from Google Patents.
US2674657A
Expired / Lapsed
US
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Primary-secondary-spread crossbar telephone system
Assignee: TDK Micronas GmbH
•
Filing: 1949-04-04
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Granted: 1954-04-06
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Expires: 1969-04-04
Abstract
No abstract record available.
Inventors
- 👤 John I Bellamy
- 👤 Theron I Bowser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:08
CPC Classifications
H; H04; H04Q; H04Q3/00; H04Q3/0004
Claims Analysis
Total Claims: 0
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-04-05 | 1957-10-05 | 1958-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-04-05 | 1961-10-05 | 1962-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-04-05 | 1965-10-05 | 1966-04-06 | $7700.00 | Window Closed / Lapsed |