Patent ID: 6925039
Filing Date: 2005-08-02
Classification: G11B

Abstract:
1. A tilt servo control device of an information recording/reproducing apparatus for recording information on and reproducing information from an optical recording medium, said apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a split type photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector, said device comprising: a push-pull component generator for generating a push-pull component signal including a differential component of output signals of respective split portions of said photo detector; a tilt error signal generator for generating a tilt error signal representing a tilt angle between a normal to the recording surface of said optical recording medium at a position of said laser beam irradiating the recording surface and an optical axis of said laser beam based on said push-pull component signal; a tilt angle adjuster for adjusting said tilt angle; a driver for driving said tilt angle adjuster so as to reduce said tilt error signal; and a holder for holding, as a reference signal, a signal obtained by smoothing said push-pull component signal corresponding to said read signal showing a desired level at a predetermined area of said optical recording medium: wherein said tilt error signal generator generates the tilt error signal in accordance with the difference between said signal obtained by smoothing said push-pull component signal and said reference signal.