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Tracking error detection device

  • US 6,741,533 B1
  • Filed: 08/06/2001
  • Issued: 05/25/2004
  • Est. Priority Date: 08/30/1999
  • Status: Expired due to Fees
First Claim
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1. A tracking error detecting apparatus for detecting a tracking error of an optical spot obtained by radiating light on an optical recording medium, said tracking error detecting apparatus comprising:

  • a photo detector for receiving reflected light of the optical spot and outputting photoelectric current according to a photo acceptance quantity;

    a plurality of current/voltage conversion circuits for converting the photoelectric current of the photo detector into voltage signals;

    a plurality of signal generators for generating two signal series, phases of the two signal series changing with respect to each other according to a tracking error of the optical spot, from the voltage signals;

    a plurality of analog-digital converters for discretizing the two signal series to obtain first and second digital signal series;

    a plurality of interpolation filters for performing interpolation processing of the first and second digital signal series, respectively;

    a plurality of zero cross point detector circuits for respectively detecting zero cross points of the first and second digital signal series interpolated by the interpolation filters;

    a phase difference detector circuit for detecting a phase difference between the zero cross point of the first digital signal series and the zero cross point of the second digital signal series; and

    a low-pass filter for performing band restriction toward the detected phase difference to obtain a tracking error signal.

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