Optical head using image sensor of XY address type in photo detector

摘要

A CMD of XY address type is used as a photo detector. X and Y address signals output from the X and Y address generating circuit are applied to the CMD mechanically fixed to an optical head. Output from the CMD is binary-coded by a binary-coded circuit. A central position of a duration in which "H" continues in a mean-value circuit is stored by an X and Y address detection & memory circuit as a reference XY address. An address range is set in which reading is executed on the basis of the reference XY address. The XY address within this address range is assigned to produce an optical picture element signals within a corresponding light receiving region. A playback signal, a focus error signal and a tracking error signal are generated from the optical picture element signals.