| 摘要 |
PURPOSE:To drive and adjust a lens by receiving reflected pulse light from a subject and generating 1st and 2nd currents according to the light reception position, removing a stationary light component from the currents and extracting contribution components of only pulse light, and performing logarithmic compression and then measuring the distance from the difference in value. CONSTITUTION:A pulse circuit 32 turns on an LED 12 for a short time and a memory 38 is reset. The outputs of light receiving elements 20 and 22 are supplied to a logarithmic converting circuit 34 and only respective output pulse parts are amplified and converted logarithmically to output a voltage value. An arithmetic circuit 36 finds the difference and inputs it to the memory 38. The output of the arithmetic circuit 36 is a signal corresponding to the distance to the subject 16. An image pickup lens 40 is moved after the distance measurement signal is stored in the memory 38 and a lens position signal corresponding to focusing distance is detected by a circuit 42 and compared 44 with the stored value in the memory 38; when they match with each other, a magnet 46 is turned off and a lock claw 48 stops the movement of the lens 40. In this state, the photographic lens 40 is set to the focusing distance corresponding to the distance to the subject 16. |
