Limbach & Limbach L.L.P.
Disc drive apparatus
 An optical pickup is provided with a main beam for performing recording or playback on a disc and an advance beam in a position ahead of this main beam to detect the surface state of the disc; the surface state of the disc is detected on the basis of the light reception information (an MO signal or an RF signal) of this advance beam; and control is so effected that, at the timing of the main beam passing the position where adhesion of dust or the like to the disc is detected, the laser output power of the main beam reach a level at which satisfactory operation can be executed even if there is dust adhesion or the like so as to make possible execution of accurate recording and playback operations, even if the thickness of a disc-shaped recording medium is thinned, without being affected by dust or the like stuck to the surface of the disc-shaped recording medium. 
Sony Corporation
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Tetsu
Watanabe