Pulse generating circuit for detecting aperture size of camera shutter.

摘要

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 (20) 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 (11). A series combination of a switch (14), which is turned on and off by the output voltage of the comparator, and a resistor (R2) is connected between the output (PIP) 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.