| 摘要 |
PROBLEM TO BE SOLVED: To perform a correct tracking control even though the diffraction direction of the reflected light from information tracks is changed by determining combinations of light receiving elements for calculating push-pull error signals in accordance with the rotational angle of a rotary optical part. SOLUTION: Reflected diffraction light beams rotate around the light receiving center of light receiving elements 14 with the rotating operation of a rotary optical part 104 from their diffraction directions. The light receiving element 14 transmits a current corresponding to the received light quantity of light intensities to be obtained from 8 pieces of respective light receiving elements to a tracking error signal generating part 16. In a servo circuit 17, a servo signal is transmitted to an actuator 11 based on a tracking error signal STE and the actuator 11 is driven so as to be controlled in the vertical direction of tracks so that a light beam follows on tracks. Consequentry, an optimum light receiving element is selected in accordance with the rotating operation of the rotary optical part 104. Thus, a correct tracking error signal in accordance with the tangential line direction of information tracks is obtained. |
