| 摘要 |
PURPOSE:To simplify a circuit by providing a light projection driving means which increases the output of a light projecting means gradually, a means which detect the sum of photodetection outputs attaining to a specific value, an output difference calculating means for a photodetecting means, and a means which latches its output as distance information. CONSTITUTION:A power source switch 2 is turned by the 1st stroke of release operation and a pulse generator 3 sets an RS-FF6. A constant voltage generating circuit 4 generates constant voltages VC and KVC (KVC>VC), a capacitor 11 is discharged through a resistance 9, and an IR light emitting diode 17 while increasing in output turns on and off corresponding to a CLK. Reflected light from a subject 19 is incident to one point of a semiconductor position detector 21 and outputs electrodes A and B are inputted to switches 36 and 37 through OPAmps 24 and 25 and frequency selecting circuits 26 and 27 and integrated by integrating circuits 38 and 41; the sum and difference are calculated by resistances 47-50, and 53-56 and while charging is stopped by a comparator 58 and the FF6, a latch circuit 60 latches the difference signal. |
