Patent ID: 7580332

Claim:
An optical pickup comprising: a light source configured to emit light beams; an objective lens configured to condense the light beams emitted from the light source so that an optical disk is irradiated with the condensed light beams; a first light detector and a second light detector having respective light-receiving surfaces; an optical system configured so that reflected light beams caused by reflection of the irradiating light beams by the optical disk are transmitted through the objective lens to form a single light spot on each of the light-receiving surfaces of the first and second light detectors; and error-signal generating means for generating a focus-error signal and a tracking-error signal on the basis of detection signals output from the first and second light detectors when the light spots are formed on the respective light-receiving surfaces; wherein the light-receiving surface of at least one of the first and second light detectors has a width extending in a first direction corresponding to a radial direction of the optical disk, wherein the light-receiving surface of the at least one light detector is formed by first to sixth photoreceptors arrayed along the first direction, wherein the first and second photoreceptors are disposed axisymmetrically with respect to a center line passing through the center in the width direction and extending in a direction perpendicular to the first direction, wherein the third and fourth photoreceptors are respectively disposed continuously outward from the first and second photoreceptors so as to be axisymmetric with respect to the center line, wherein the fifth and sixth photoreceptors are respectively disposed continuously outward from the third and fourth photoreceptors so as to be axisymmetric with respect to the center line, and wherein the error-signal generating means is configured to generate the focus-error signal by using one of a first sum signal of detection signals output from the first and second photoreceptors and a second sum signal of detection signals output from the first to fourth photoreceptors as a detection signal in a light spot size method, and to generate the tracking-error signal by mathematically combining detection signals output from at least the first, second, third and fourth photoreceptors as a correction signal in a differential compensate push-pull method.