Exposure control system
US3945025A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 21, 1974 |
| Grant date | Mar 16, 1976 |
| Priority date | — |
| Expiry date | Nov 21, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B7/095
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An exposure control system for photographic apparatus of a variety utilizing a pulse driven stepper motor to drive the light regulating elements of an exposure mechanism. The control system utilizes an exposure evaluating network, the output signal from which is converted to binary form and compared against the count output of counter means driven at a predetermined frequency. The system operates to count at one pulse frequency while simultaneously driving the stepper motor at a submultiple frequency until equality is reached with the binary representation. Supplementary counting continues at the one frequency in response to any deviation between the value of exposure derived by the exposure mechanism elements and the value of exposure represented by the binary representation. The deviation is accommodated for by a digitally derived delay corresponding therewith. In effect, a vernier form of binary regulation of exposure is provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.