GB1165735A - Improved Shutter Speed Governor - Google Patents

Abstract

1,165,735. Photographic apparatus. NIPPON KOGAKUK.K. Oct. 10,1966, No.45111/66. Heading G2A. A camera shutter control comprises a drive means which is moved to a first position on activation and is delayed there by an electronic circuit, then, on moving to a second position, the drive means causes the shutter to open and after a delay determined by the circuit causes the drive means to move from the second position and close the shutter. As shown, the drive means is a spring-driven rotating cam-plate having upper and lower cams 10a, 10b and carrying a pin 11, which before activation holds open a switch S, in an electronic circuit. On release by a lever 14, the cam-plate turns and the switch S, closes, thereby energizing an electromagnet M which holds a stop-lever 26 in the path of the pin 11. A condenser in the circuit charges through a resistor and after a delay determined by the resistor passes a signal current to a transistor arrangement which de-energizes the magnet M, allowing the cam-plate to turn. Cam cob then abuts a roller 20 or a biased switch lever 17 thereby momentarily closing a swich S2 which causes the condense to discharge and the electromagnet to be re-energized. The roller 20 then moves along the edge of the cam-plate and closes switch S3 which causes the condense to recharge through a second resistor e.g. a manually variable or photo-resistor, to determine the exposure time, and simultaneously the cam 10a lifts a biased stop lever 22 which releases a lever 4 connected to the front blind of a roller blind shutter. The rear blind is also released but is held in position by a pin 8 which abuts the stop lever 26. When the condenser has again charged, the electromagnet M is de -energized, and the pin 8, and thus the rear blind, is released. The self-timer may be disengaged by operating a locking member 30 having a projection 30a which holds the switch S3 closed, thereby by-passing the delay resistor.