Photographic flash meter
Abstract
Abstract A FLASH METER WITH A STATIC DISPLAY OF TOTAL LIGHT IS PROVIDED BY AN INTEGRATING CAPACITOR CONNECTED ACROSS THE GATE AND SOURCE OF A FIRST JUNCTION-TYPE FIELD-EFFECT TRANSISTOR THAT DRIVES AN AMMETER. WHEN POWER IS REMOVED FROM THE TRANSISTOR, THE GATE-SOURCE JUNCTION BECOMES FORWARD BIASED TO ALLOW THE CAPACITOR TO DISCHARGE. TO CHARGE THE CAPACITOR TO A VOLTAGE PROPORTIONAL TO THE TOTAL LIGHT OF A STROBE, A SECOND JUNCTION-TYPE FIELD-EFFECT TRANSISTOR COUPLES THE CAPACITOR TO A VOLTAGE-DIVIDING NETWORK COMPRISING A PHOTOCONDUCTIVE CELL AND A CALIBRATING POTENTIOMETER. TO TEST THE METER POWER BATTERY, A SWITCH PLACES THE BATTERY ACROSS THE AMMETER AND CHANNEL OF THE FIRST TRANSISTOR IN SERIES.
Inventors
- 👤 Stanley Weinberg
Bibliographic Details
Claims Analysis
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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) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |