| 摘要 |
PURPOSE:To stabilize the operation of an automatic exposure second controlling circuit by controlling the measurement start of the controlling circuit according to the attenuation of the quantity of light by shielding a photodetection window. CONSTITUTION:As a shutter is released, an opening and closing lever 10 swivels to left and a switch 114 is released with a pin 10f. Simultaneously, a shutter blade 14 moves to the right to shield a photodetection window 1b, opend by displacing an opening 14, temporarily, and because the switch 114 is opened, a dark current flows to a photodetecting element, starting charging a capacitor for second control. Thus, the measurement start of an automatic exposure second controlling circuit is controlled electrically, according to the attenuation of the quantity of light by shielding the photodetection window 1b, without using a mechanical switch and causing delay. Therefore, an electric circuit and an opening and closing mechanism for a shutter, etc., operate stably, thus obtaining a speed controlling circuit for a photodetection aperture coupling type program electric shutter. |
