Patent ID: 6552971
Filing Date: 2003-04-22
Classification: G11B

Abstract:
An apparatus for writing and/or reading data by emitting laser light on each signal recording surface of a recording medium having a plurality of signal recording surfaces, said apparatus comprising:pickup means having an objective lens which is at an output end of said laser light; objective lens moving means for setting the focused state of the laser light with respect to the signal recording surface of the recording medium by moving said objective lens toward or away from the recording medium; focus error signal generating means for generating a focus error signal indicating a focusing error between said objective lens and said signal recording surface; detection means for receiving said focus error signal and detecting moved distance information indicating the relative distance moved between said objective lens and said signal recording surface based on said focus error signal, said relative distance moved caused by a wobbling of the surface of the recording medium when the recording medium rotates; and focusing jump control means for controlling said objective lens moving means so that a focusing jump operation is performed for moving the focus position of said objective lens from the current signal recording surface to another signal recording surface, wherein said focusing jump control means performs said focusing jump operation at a position where said relative distance moved with respect to said recording medium is not more than a predetermined value.