| 摘要 |
PURPOSE:To accurately vary an MS time in inverse proportion to variation in source voltage by comparing the charging voltage of a charging and discharging circuit with a constant threshold voltage which does not depend upon variation in the source voltage at the final frame of a film, and detecting their coincidence and then stopping feeding electricity to a film winding motor. CONSTITUTION:When the film is not drawn out of a film case at the final frame (where the rotation of the motor 3 is stopped), the film is not run, so a switch 6 neither turns on nor off. Consequently, a capacitor Cx is charge continuously and the voltage (e) keep on rising. When the voltage (e) reaches the threshold voltage 1.14V set by the Zener diode Dz of a voltage setting circuit 17, the output (m) of the comparator 22 is held at the H level and the output of a gate 14 is held at the L level to turn off the TRs X2 and X3, thereby stopping electrical conduction to the motor 3.
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