| 摘要 |
PURPOSE:To save power and to perform smooth and highly accurate control of rotation by reading out sine wave data having a large amplitude from a memory at the starting time of rotation of a step motor and reading out a sine wave data having a small amplitude after rotation of the step motor. CONSTITUTION:A sine wave driver is provided with a ROM 1 containing four tables each storing sine wave data having different amplitude. Tables in the ROM 1 are switched based on a switching signal provided from a terminal 21 thus varying the amplitude of the sine wave. When a focus driving motor is started, amplitudes of the sine waves for phase A and B are increased. At a position where the phase A sine wave is 0 deg. immediately after rotation of the focus driving motor, amplitudes of the sine waves for phase A and B are switched to smaller amplitude. |
