Pulse generating circuit for detecting aperture size of camera shutter
US4972078A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 1989 |
| Grant date | Nov 20, 1990 |
| Priority date | — |
| Expiry date | Apr 17, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B7/097
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In at least one of a plurality of shutter vanes forming a shutter there are provided a plurality of openings adapted to detect the movement of the shutter vanes. A photointerrupter is turned on and off by the openings when the shutter vanes move. An output voltage of the photointerrupter is compared with a reference voltage by a comparator. A series combination of a switch, which is turned on and off by the output voltage of the comparator, and a resistor is connected between the output of the photointerrupter and ground. The output signal of the comparator is delayed. The delayed version and the output signal of the comparator are exclusive ORed to produce a train of pulses corresponding to the openings as the shutter vanes move. A drive and control section is responsive to the count of the pulses to control the operation of the shutter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.