Focusing control apparatus for optimally directing light onto a recording surface

摘要

A focusing control apparatus is designed to perform a focus jumping operation successfully. The apparatus has reading device which irradiates read light to a recording medium 1 having information recording surfaces formed on at least two layers, respectively, receiving return light of the read light from the recording medium, and generating a read signal; and control device which executes a focus jumping process to generate a drive signal of a focusing actuator to move an optimum light converging position of the read light from one of the recording surfaces to the other based on a focusing error signal that is generated based on the return light. The apparatus further has drop-out detecting device which detects a drop-out of the read signal and vibration detecting device which detects a vibration of the recording medium or reading device. The control device executes the focus jumping process only when the drop-out is not detected and a vibration detection level of the vibration detecting means is lower than a predetermined value.