| 摘要 |
PROBLEM TO BE SOLVED: To prevent a lens from colliding with a recording medium by detecting revolving speed to control the speed of an objective lens approaching to an optical recording medium, and detecting the approach of a focal position of a light beam to control the speed of the lens approaching to the optical recording medium, thereby making the latter approaching speed smaller than the former approaching speed. SOLUTION: The speed V1 of an objective lens 8a approaching to an optical recording medium 1 is controlled according to a rotary speed signal obtained by a revolving speed detection means comprised of FG3 is controlled so as to be V1 <d×f/60 when, for example, WD value of the lens is expressed by d, a focal depth of the lens by d2, and the revolving speed by f. It is detected that a focal position of a light beam is coming in a focus servo pull-in range, and the approaching speed V2 of the lens is controlled so as to be V2 <d2×f/60 according to the detected signal. Here, the approaching speed is controlled to be V2 <V1 . Collision is surely avoidable by providing an over-approaching detection means and operating it.
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