Track-side signalling switching of an optical disc device for correct output of the track-side signal and correct and stable execution of the search, even within a high-speed range of the light beam

摘要

A track cross signal generation circuit comprises a tracking error signal generation circuit (14), an offset compensation circuit (16), a level setting circuit (22), and a comparator (24). The comparator (24) directly receives a tracking error signal (TES) output from the tracking error signal generation circuit (14) without passing through the offset compensation circuit (16) and a reference level (Vref) output from the level setting circuit (22). Further, the comparator (24) compares the tracking error signal (TES) with the reference level (Vref), and generates a track cross signal (TZC) representing the tracks formed on an optical recording medium (12) crossed by a beam. Namely, the gain of the tracking error signal (TES) is not affected by the offset compensation circuit (16) even within a high-speed region of the beam. Consequently, the track zero cross signal (TZC) correctly indicates tracks crossed by the beam, and correctly and stably carries out a seek operation in the high-speed region of the beam. IMAGE