| 摘要 |
<p>PURPOSE:To simplity constitution by determining the aperture value depending upon to which of plural stages of regions the exposure value belongs and controlling the exposure second time by the full-aperture F value when it is on the open side than the full-aperture F value and by the determined aperture value in other cases. CONSTITUTION:The output voltage of an operational amplifier OP5 corresponds to an exposure value Ev and the stage to which Ev belongs is discriminated by comparators COM1-COM4. The pulses of the number corresponding to that stage are generated by the oscillating circuit OS operated by releasing of a switch S3, a shift register SR and AND gates AG1-AG4 to drive an electromagnetic coil MF, whereby the aperture diameter is determined. On the other hand, the sum of the full aperture F value when the determined aperture value is on the open side than the full aperture F value and the voltage corresponding to the determined aperture value in other cases and the voltage corresponding to the -Ev respectively is inputted to the inversion input terminal of an operational amplifier OP7, and the voltage corresponding to the exposure second time being the inverted voltage thereof appears in the output of OP7.</p> |
