| 摘要 |
PROBLEM TO BE SOLVED: To accurately perform focusing at a high speed by setting the number of times for integrating infrared pulse emission according to a required S/N ratio and a range finding time and switching over focusing position setting methods according to the change in setting. SOLUTION: A light of a pulse-like infrared ray emitted from an infrared ray emission diode 2 reflected from a subject is received by a position detecting element 5 and currents I1 and I2 corresponding to subject distance are inputted to pre-stage amplifiers 13 and 14. The outputs of the amplifiers 13 and 14 are respectively inputted through channel changeover switches 15 and 16 to a BPF 17. An integration amplifier 19 integrates the output of the BPF 17 for every generation of a sample pulse (e) from a sample pulse generator 22 and an integrated output voltage V1 is compared with a reference voltage Vref by a comparator 20. An arithmetic control means performs switching control for the switches 15 and 16 according to the result of the comparison, sets the number of times for integration considering range finding accuracy and time and performs focusing by switching over the focusing position setting methods according to the change in setting. |
