Patent ID: 8270264

Claim:
An optical head apparatus, comprising: a semiconductor laser; an objective lens that focuses a light beam emitted from the semiconductor laser, to form a focus spot on an information recording layer of an optical disk; and a light receiving device that converts into an electrical signal an amount of a return optical beam created by the focus spot being reflected by the information recording layer, to detect a playback signal of the optical disk, a focal point error, and a tracking error, wherein the light receiving device includes a light receiving surface that is configured with a first light receiving surface that includes a plurality of light receiving elements that receives outer portions of the return optical beam, and with a second light receiving surface that includes a plurality of light receiving elements that receives a center portion of the return optical beam, the first light receiving surface and the second light receiving surface being split in a predetermined direction which is in a plane of the light receiving surface and corresponds to an orthogonal direction to a radial direction of the optical disk, at least one of the light receiving elements of the first light receiving surface being spaced from a center of a position where the return optical beam is arranged to be focused, on a positive side in the predetermined direction, by a first distance, and the other of the light receiving elements of the first light receiving surface being spaced from the center of the position where the return optical beam is arranged to be focused, on a negative side as opposed to the positive side, by a second distance which is larger than the first distance, and a plurality of signal level converters that individually adjust levels of electrical signals received from the plurality of light receiving elements of the first light receiving surface and the plurality of light receiving elements of the second light receiving surface, the signal level converters amplifying the electrical signals received from the plurality of light receiving elements of the first light receiving surface by a first gain and amplifying the electrical signals received from the plurality of light receiving elements of the second light receiving surface by a second gain which is less than the first gain, and wherein the playback signal generated by combining together the amplified electrical signals received from the plurality of signal level converters, is output.