| 摘要 |
PURPOSE:To perform stable detecting operation without any variance in response time at a wide-angle nor a telephoto side by providing a control circuit which is driven by a focusing lens part at an invariably constant driving speed. CONSTITUTION:When the level of a sum signal 31 is sufficiently high, the output of a multivibrator 44 is supplied to a multiplier 50 through an AND gate 49 and outputted periodically. At this time, the terminal voltage across a resistance 42, i.e. driving force corresponding to the settling zoom ratio of a zoom lens and a difference signal supplied from the output terminal 24 of an amplifier 23 to a terminal 51, i.e. a signal with a peak value corresponding to the product of the extent of defocusing is outputted and applied to a motor 39 as a driving signal. Then, the motor 39 is driven to move a focusing lens 35 for focusing operation. When the level of the sum signal 31 inputted to a terminal 45 is low, the output of a comparator 47 goes down to a low level and the output of an inverter 52 goes up to a high level; and the amplifier 53 controls the motor 39 on servo basis with the difference signal 30 inputted to the terminal 51 to settle the focusing of the lens 35. |
