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Apparatus for scanning optical recording media using DPD tracking method with analog and digital delay elements

  • US 20040151089A1
  • Filed: 01/21/2004
  • Published: 08/05/2004
  • Est. Priority Date: 11/13/1998
  • Status: Active Grant
First Claim
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1. ) Apparatus for reading from or writing to optical recording media, comprising:

  • a tracking device, a four-quadrant detector, two summation points, a phase comparator for tracking in accordance with the differential phase detection method, and variable delay elements that can be set by a control device, wherein at least one of said variable delay elements is a digital variable delay element and at least one of said variable delay elements is an analog variable delay element, wherein at least one of said variable delay elements is arranged between one of said summation points for output signals of detector elements of the four-quadrant detector and said phase comparator, and at least one of said variable delay elements is arranged between said four-quadrant detector and one of said summation points, wherein no digital variable delay element is arranged between said four-quadrant detector and one of said summation points.

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