| 摘要 |
PURPOSE: An optical disk having different-depth pits is provided to solve the problem that tracking servo control is not properly performed in the conventional method such as the phase difference method or push-pull method due to possibility for generating polarity inversion of tracking signals according to a deep pit and a shallow pit. CONSTITUTION: A row of plural pits having two kinds of depth is formed on an optical disk. The amount of light reflected from the pit row is detected by a photosensitive diode(2). Each pit-depth detecting unit(3-3,3-4,4,10,11,12,13-1,13-2,14-1,14-2,15-1,15-2,16-1,16-2) detects the depth of each pit based on the detected amount of reflected light. A plurality of servo signal generators(3-1,3-2,5-1,5-2,7,8-1,8-2,9) generate tracking servo signals according to the defected amount of reflected light. Output control units(19,20) output the generated tracking servo signals in tracking of a pit of depth to be played, based on the detected result of the pit-depth detecting units. In tracking of another depth pit, the tracking servo signals immediately before the operation are held and output.
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