Patent ID: 6229771
Filing Date: 2001-05-08
Classification: G11B

Abstract:
An optical pickup assembly for simultaneously reading a plurality of data tracks from an optical disk, the optical pickup assembly comprising:means for producing a plurality of reading beams;an objective lens that focuses the plurality of reading beams onto the plurality of data tracks of the optical disk;a plurality of data detectors, each data detector producing a data signal responsive to an amount of light illuminating the data detector;a first focus detector spaced apart from the plurality of data detectors, the first focus detector comprising a plurality of photodetector segments wherein adjacent ones of the photodetector segments have unequal areas, each photodetector segment producing a signal responsive to an amount of light illuminating the photodetector segment, the first focus detector generating a focus error signal responsive to the presence of a focus error by combining the signals produced by the photodetector segments; andan optical element that splits beams reflected from the optical disk into a plurality of data beams and a plurality of focus beams not used for recovering data from the optical disk, the optical element introducing astigmatism into the plurality of focus beams and directing one of the plurality of focus beams to the first focus detector and the plurality of data beams to the plurality of data detectors.