| 摘要 |
PURPOSE:To move a lens to a prescribed position exactly and quickly, by driving a step-motor in order by a signal from a step-motor rotation detecting part installed to a rotary shaft of the step-motor. CONSTITUTION:When a changeover switch 15 is set to a short circuit from an open circuit, a counter in a controlling circuit 16 is loaded, and by its output, a step-motor 4 is rotated by one phase portion in the direction as indicated with an arrow. As a result, a telephoto lens 7 starts to move. Subsequently, a rotation of a disk 18 which is directly coupled with the step-motor 4 is detected by a detector 17, and when the counter in the controlling circuit 16 is counted by its detection signal, the step-motor 4 is rotated to the next phase through a driving circuit 3. In this way, the step-motor is accela-rated in order, following which the telephoto lens 7 is accelerated in order, proceeds to a position of a standard lens 11, and at this fixed position, the controlling circuit 16 is stopped by a detector 14, by which the telephoto lens 7 is fitted into the standard lens 11. |
