Patent ID: 8068389
Filing Date: 2011-11-29
Classification: G11B

Abstract:
1. A tracking error signal detection device employing a differential phase detection method, comprising: first and second differentiators which remove direct current components included in first and second signal groups in which a phase difference between the first and second signal groups changes in accordance with a tracking error signal, and which differentiate the first and second signal groups; a first analog/digital converter which samples and quantizes a signal output from the first differentiator; a second analog/digital converter which samples and quantizes a signal output from the second differentiator; a Hilbert transformer which performs a 90-degree phase shift on a signal output from the first analog/digital converter or a signal output from the second analog/digital converter irrespective of a cycle of a signal component; a delay circuit which delays the signal output from the second analog/digital converter or the signal output from the first analog/digital converter by an amount of delay equal to that caused by the Hilbert transformer; and a phase comparator which calculates a phase difference between a signal output from the Hilbert transformer and a signal output from the delay circuit.