| 摘要 |
PURPOSE:To obtain an accurate timing signal without any adjustment under the influence of none of the responsibility, temperature variation, and the source voltage variation of a photocoupler by detecting the peak of the output signal of the photocoupler and inverting the output of an FF. CONSTITUTION:When a leading curtain begins to run, a cam 40 rotates and a projection part 41 cuts off luminous flux 51a from an LED51 temporarily to raise the output e1 of a phototransistor PT52; when the projection part 41 passes through the luminous flux 51a, the output e1 drops. The time position of the peak value of the output e1 is constant when the rotating speed of the cam 40 is constant. The output e2 of a capacitor C3 and an amplifier A11 is held at the peak voltage with the output e3 of an amplifier 10, and an amplifier A10 operates as a comparator, so that outputs of gates G1 and G2 forming the FF are inverted according to variation in the level of the output e3. Transistors Q4 and Q5 are therefore turned off with the output of the G2 and the C2 begins to be charged, thereby clocking a shutter second time.
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