1. Field of the Invention
The present invention relates to an optical pickup, an information processing apparatus and a signal processing method, and more particular to an optical pickup, an information processing apparatus and a signal processing method, each enabling accurate execution of the detection of a track error signal and a focus error signal.
2. Description of the Related Art
Recently, many optical disks (including magneto-optical disks) have been used as recording and reproducing media of digital data. The optical disks are, for example, a compact disk (CD), a mini disk (MD), a digital versatile disk (DVD) and the like.
In data recording and reproducing in which such an optical disk is applied, the positional control of an optical pickup becomes necessary, and the detection of a return light from a disk read by the optical pickup is performed, for example, for tracking servo and focus servo. For example, the light spot detection of the return light from the disk is performed with a photodetector composed of divided light receiving elements.
As related art disclosing a signal detection configuration for servo, for example, there is Japanese Patent Application Publication No. Hei 11-353666. Japanese Patent Application Publication No. Hei 11-353666 discloses a photodetector configuration divided into three portions of the central portion and both end portions in the direction perpendicular to a radial direction corresponding to a radial direction of a disk to detect a radial error signal.
However, the configuration shown in Japanese Patent Application Publication No. Hei 11-353666 has only a track error signal as the signal acquired by the radial error signal, and must configure another photo-detection system including a photodetector and an optical system for the detection of a focus error. Consequently, the configuration has a problem in which the apparatus configuration becomes complicated and larger in size. Furthermore, there is another problem of the impossibility of the correction of an offset of the DC level of a track error signal to a lens shift when a beam size and a shape on a light receiving portion change owing to a focus shift, aberration and the like in the case of the detection of the track error signal pursuant to the system.