| 摘要 |
PROBLEM TO BE SOLVED: To improve accuracy of automatic adjustment by accurately measuring a defective signal. SOLUTION: An optical disk playback apparatus includes: an objective lens 10 and a light receiving element part reading a signal from an optical disk 1; a CPU 60 determining whether three signals read by the objective lens 10 and the light receiving element part are the defective signals or not in accordance with whether at least values of three signals are within the prescribed range or not; a tracking control part 71 which, when the signals read by the objective lens 10 and the light receiving element part are determined to be the defective signals, uses a signal read by the objective lens 10 and the light receiving element part immediately before reading the defective signal instead of the defective signal to generate a signal indicating the estimated position of the objective lens 10, and when the value of the received signal indicates that the received signal is not the defective signal, generates a signal indicating the same contents as the signal read by the objective lens 10 and the light receiving element part; and an actuator 11 changing the position of the objective lens 10 with respect to the optical disk 1 in accordance with contents of the signal generated by the tracking control part 71. COPYRIGHT: (C)2006,JPO&NCIPI
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