| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve such a problem that when information is recorded/reproduced for a multi-layer optical disk in an optical pickup device by a three-beam system, an interference state of stray light from the other layer and reflected light from a reproducing layer is varied due to uneven thickness of an intermediate layer, and tracking and focus control become instable. Ž<P>SOLUTION: The optical pickup device is provided with first and second light sources that are driven selectively and that emit blue and red light beams; an optical element for splitting the emitted blue and red beams into main and sub-blue beams and main and sub-red beams; first and second photodetectors that receive the main and sub-blue beams reflected from the optical disc to output electrical signals; and third and fourth photodetectors that receive the main and sub-red beams reflected from the optical disc to output electrical signals. A dead zone that outputs no electrical signal representing the intensity of the light is provided for respective parts of the second and the fourth photodetectors. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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