| 摘要 |
PURPOSE:To prevent one of manual focusing operation and manual variable power operation from affecting the other operation by providing a differential gear train which generates a corresponding output when one of a manual operating means and a motor-driven operation is performed and generates a composite output when the both means are in operation. CONSTITUTION:A photointerrupter 53 detects the operation of a manual rotary cylinder 25 and a photographic lens is stopped from being driven for automatic focusing. Namely, when the manual rotary cylinder 25 is operated, a rotary disk also rotates in one body, so the photointerrupter 53 sends out a pulse signal according to the rotation and when the photointerrupter 53 generates more than a constant number of pulses within a constant time, the CPU 29 in the lens decides that the manual focusing operation is in process, thereby sending a signal for stopping the motor driving to the CPU 111 in the body. Consequently, when either of the focusing operation and variable power operation by the manual operating means is in process, the other operation is prevented from being affected by the mechanism of simple constitution. |
