| 摘要 |
PURPOSE:To improve the speed of recording/reproduction/erasure of information by moving a support means of a recording medium to apply focusing at a comparatively low frequency and moving a part of an optical system to apply focusing at a comparatively high frequency in applying focusing of a light beam spot. CONSTITUTION:An electric signal from a 4-split light sensor 9 is inputted to a focusing error detection circuit 21 and a focusing error signal is outputted from a detection circuit 21. The focusing error signal is divided into a low frequency and a high frequency component, the low frequency component is inputted to the 1st actuator drive circuit 22 and the high frequency component is inputted to the 2nd actuator drive circuit 23. The 1st drive circuit 22 is used to drive the 1st actuator 20 to reciprocate a spindle motor 15 in a direction vertical to the recording medium face, and the 2nd drive circuit 23 is used to drive the 2nd actuator to reciprocate an objective lens 4 in the optical axis direction. |
