| 摘要 |
PURPOSE:To detect focus and tracking control signals with a simple constitution by setting the direction of the division line of the first optical detecting means to the track direction approximately and providing the second optical detecting means in an approximate convergence position of a reflected light so that the direction of its division line is vertical to the track direction approximately. CONSTITUTION:A photodetector 7 has a two-divided structure, and the direction of a division line 23 is set to the track direction. Outputs from a light receiving parts 21 and 22 are inputted to a differential amplifier 15 and are applied to a tracking element 11 through a phase compensating circuit 16 and a driving circuit 17. A photodetector 8 is placed in the convergence position of a reflected light 6 approximately and has a two-divided structure, and the direction of a division line 26 is vertical to the track direction. Outputs of light receiving parts 24 and 25 are inputted to a differential amplifier 12 and are applied to a focusing element 10 through a phase compensating circuit 13 and a driving circuit 14. Thus, focus and tracking control signals are detected with a simple constitution. |
