Patent ID: 7697383
Filing Date: 2010-04-13
Classification: G11B

Abstract:
1. An optical disc reproducing apparatus comprising: an objective lens through which a light beam generated by a light source is irradiated on a recording surface of an optical disc and that receives reflected light from the optical disc; an actuator that moves the objective lens in a radial direction of the optical disc; a light receiving portion that has a first light-receiving region and a second light-receiving region formed therein by being equally divided into at least two areas in a direction parallel to a track of the optical disc and that detects the reflected light from the optical disc by each of the light-receiving regions; an information output portion that feeds out information recorded in a track of the optical disc in accordance with a sum of two output signals resulted from detecting the reflected light by the first and the second light-receiving regions respectively; a light-receiving ratio calculation portion that calculates a light-receiving ratio that is a ratio between an amplitude of an electric signal generated in the first light-receiving region and an amplitude of an electric signal generated in the second light-receiving region; a ratio determination portion that determines whether or not an absolute value of the light-receiving ratio is larger than a predetermined value; a post-correction ratio calculation portion that calculates a post-correction ratio by attaching a sign of the light-receiving ratio to a value obtained by subtracting a predetermined correction value from the absolute value of the light-receiving ratio and that calculates a direction and a distance of the objective lens required to be moved radially so as to make the light-receiving ratio identical with the post-correction ratio when the ratio determination portion determines that the absolute value of the light-receiving ratio is larger than the predetermined value; and a correction parameter memorizing portion that memorizes a result thus calculated by the post-correction ratio calculation portion as a correction parameter, wherein, when the actuator moves the objective lens, a movement of the objective lens in a radial direction is corrected based on the correction parameter.