Patent US2838370A successfully refreshed from Google Patents.
Patent US3568430A successfully refreshed from Google Patents.
US3568430A
Expired / Lapsed
US
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Resistance bridge controlled timekeeping device
Assignee: Hamilton Watch Co
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Filing: 1968-07-11
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Granted: 1971-03-09
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Expires: 1988-07-11
Abstract
Abstract THERE IS DISCLOSED HEREIN AN ELECTRONIC TIMEKEEPING DEVICE EMPLOYING A PASSIVE CIRCUIT ELEMENT AS A MASTER FREQUENCY REFERENCE, COMPRISING A MOTOR DRIVEN GEAR TRAIN AND HANDS AND A FEEDBACK CONTROL CIRCUIT FOR THE MOTOR INCLUDING A SPEED TRANSDUCER, AND AN ERROR DETECTION CIRCUIT INCLUDING A RESISTANCE BRIDGE AND A DIFFERENTIAL AMPLIFIER. THE AMPLIFIER OUTPUT OPERATES A CONTROL CIRCUIT WHICH PROVIDES ADJUSTABLE EXCITATION FOR THE MOTOR TO MAINTAIN THE DESIRED OPERATING SPEED. AN ULTRA HIGH PRECISION RESISTOR WITH AN EXTREMELY SMALL RESISTANCE-TEMPERATURE COEFFICIENT, IS EMPLOYED IN THE RESISTANCE BRIDGE CIRCUIT AS THE MASTER FREQUENCY REFERENCE.
Inventors
- 👤 Richard S Walton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:31
CPC Classifications
G; G04; G04C; G04C3/00; G04C3/16; Y; Y10; Y10S; Y10S388/00; Y10S388/923; Y10S388/934
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |