| 摘要 |
PURPOSE:To move a lens to an objective position at a time by detecting the extension of pulse generating intervals based on the rotating operation of a motor at the time of starting the motor and restarting the counting of generated pulses. CONSTITUTION:An automatic focusing device is provided with a means 6 for detecting the extension of pulse generating intervals based on the rotating operation of the motor at the time of starting the motor and a reset means for restarting the counting of generated pulses from the detecting point of time. When backlash exists at the time of starting motor driving, encoder pulses based on the rotation of the motor are generated at comparatively short intervals and the interval is gradually shortened in accordance with the acceleration of the motor. When the lens starts to move after the generation of pulses corresponding to the backlash, torque is suddenly increased and the interval of the encoder pulses is suddenly extended. Since the encoder pulses include the backlash up to a point of time suddenly extending the torque, the objective number of counts is reset at the time of ending the backlash to execute accurate lens driving including no backlash. |
