JPS6455747A - Optical disk tracking device - Google Patents

Abstract

PURPOSE:To obtain the constitution easily capable of integration without generating off-setting and drifting by controlling an integrating means with a defect detecting force based on the phase difference in a bisected photoelectric converting output through a reproducing head and making a tracking error signal into a numeric value. CONSTITUTION:By two sets of quadrisected photodiode 2a of a reproducing head 2, a phase difference signal A or B in accordance with a track dislocation quantity is outputted from a phase comparator 3 in a track dislocation direction and a pulse control is outputted from a pulse string converting circuit 5 to which an oscillation pulse from an oscillator 4 is supplied. The pulse string is integrated by a counter 6, first and second memory circuits 7 and 8, full adders 9, etc., and a numeric value digital tracking error signal is formed, simultaneously, the storing of the circuit 7 is prohibited by a defect detecting circuit 14, and the erroneous integration is not executed. Thus, the off-setting and drifting occur, an A/D converter to need many resistances for comparing and so forth is not necessary, and the constitution easily capable of integration without generating the off-setting and drifting with high reliability is obtained.