| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk device improving accuracy in reading information recorded in an optical disk even when the positional error of a 4-division detector used for focus control by an astigmatism method and lens are largely shifted, and to provide a focus control method thereof. <P>SOLUTION: The optical disk device is provided with a cylindrical lens 106 for generating astigmatism in a reflected light from an optical disk 105, a 4-division detector 107 having four light receiving areas divided by a line parallel to the radial direction to the optical disk 105 and a line parallel to the tangential direction of the optical disk 105 and adapted to receive the reflected light via the cylindrical lens 106, and a light shielding element 108 for preventing the reflected light from being reflected within the range of a predetermined distance from a boundary line between the areas divided by the line parallel to the radial direction of the optical disk 105 among the four light receiving areas. <P>COPYRIGHT: (C)2009,JPO&INPIT |
