| 摘要 |
PURPOSE:To prevent mis-focusing and to improve the tracking to a moving object by driving and controlling a focusing member in a direction by a moving direction code selected by a selection means when a focus voltage is changed suddenly more than a reference value. CONSTITUTION:When a comparator 8 detects a sudden change in a focus voltage A, its output signal rises from L to H. Moreover, the phase of a level vibration component B is disturbed by the sudden change in the focus voltage A and a direction discrimination circuit 11 applies erroneous direction but it is interrupted by switches 17, 18. While an output signal of a latch circuit 15 is at H, a motor drive circuit 20 drives a pulse motor 21 based on the moving direction data read from the direction memory 12. Then the master lens 2 is moved while it is vibrated in a direction set before the sudden change in the focus voltage A succeedingly. When the focus voltage A is made stable, the level vibration component is made stable within one period of a timing signal E. |
