Analog/digital control arrangement for photographic apparatus
US4058819A · kind A · utility
2Cited by
5References
9Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jun 3, 1975 |
| Grant date | Nov 15, 1977 |
| Priority date | — |
| Expiry date | Jun 3, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B7/10
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A bridge circuit which includes a photoelectric transducer furnishes input signals to a differential amplifier whose analog output signal varies in correspondence to the bridge unbalance. A first and second bistable threshold circuit changes the analog output signal into digital signals signifying bridge unbalance in a first direction, balance, and unbalance in the opposite direction, a motor is energized to rotate in a direction corresponding to the direction of bridge unbalance. The motor can be utilized to move the objective lens of a slide projector or change the aperture of a diaphragm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.