| 摘要 |
PROBLEM TO BE SOLVED: To provide a photometric device which avoids an inrush current and discriminates a photocurrent generated by the luminance of a subject, in a lens-fitted photo film unit with only a limited power source. SOLUTION: The photometric device comprises an SPD 12 which converts the luminance of a subject to a photoelectric current, a photometric switch 100 which carries out ON/OFF changeover of a current from an electric battery 49, and a photometry control IC, wherein this photometry control IC comprises a timer circuit 104, a switching transistor 114, and a photometric circuit 102. An inrush current generated by turning-on of the photometric switch 100 causes to flow in the timer circuit 104, and when a capacitor 110 is saturated, the base current of the switching transistor 114 is cut off and operation stops. Linked with this is a photocurrent caused to flow in an amplifier circuit 106 to start the operation. A photometry signal output from the amplifier circuit 106 is discriminated by a discrimination circuit 108, and in the case of below a prescribed value, a solenoid 118 causes a current to flow. COPYRIGHT: (C)2005,JPO&NCIPI
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