| 摘要 |
PURPOSE:To make stable track jump possible even in case of the use of an optical disk where a guide groove is partially deformed or broken, by providing a detecting means which detects partial deformation or break of the guide groove and a spot light moving means which moves the spot light on only the guide groove part which is not deformed or broken. CONSTITUTION:When the light spot is in the center in the breadthwise direction of a guide groove 10, the light intensity distribution of reflected light beams 43 is symmetrical in the breadthwise direction of the guide groove 10, and the intensity of light of reflected light beams 43c incident on a hotodetector 6c and that of reflected light beams 43d incident on a photodetector 6d are equal to each other. If the light spot is deviated right with respect to the guide groove 10, the intensity of light of reflected light beams 45c of reflected light beams 45 is higher that that of reflected light beams 45d, and the quantity of incident light of the photodetector 6c is larger than that of the photodetector 6d. that is, deviation of the light spot to the guide groove 10 is detected in accordance with the position of the light spot to the guide groove 10 and the light intensity distribution of the reflected light beams. A means 22 drives an objective lens 2 in the direction of the optical axis [(z) direction] and performs the focusing control to condense a luminous flux on an optical disk 1 as a minute spot.
|
