Patent ID: 7177244
Filing Date: 2007-02-13
Classification: G11B

Abstract:
1. An optical disk apparatus that reads predetermined information including address information for determining a position and wobble information from an optical disk having tracks in which information is to be recorded and that form a wobble of a predetermined cycle and gap portions between the tracks in which the address information is recorded, the optical disk apparatus comprising: an optical head having a tracking detector for detecting a first detection signal and a second detection signal by first and second detectors, respectively, arranged on both sides of a dividing line that extends in a longitudinal direction of the tracks, based on reflected light of a laser beam irradiated onto the optical disk; a wobble detection balance adjustment circuit for receiving the first detection signal and the second detection signal, making an adjustment so that a signal level of the first detection signal is equal to a signal level of the second detection signal, and outputting the respective detection signals; a wobble detection differential circuit for generating a wobble detection differential signal indicating a difference between the first detection signal and the second detection signal whose signal levels have been adjusted by the wobble detection balance adjustment circuit; an analog-to-digital conversion circuit for digitizing the wobble detection differential signal generated by the wobble detection differential circuit; a wobble signal detection circuit for detecting a wobble signal based on the wobble detection differential signal digitized by the analog-to-digital conversion circuit; an adder circuit for generating a sum signal indicating a sum of the first detection signal and the second detection signal whose signal levels have been adjusted by the wobble detection balance adjustment circuit; a binarization circuit for comparing the sum signal generated by the adder circuit with a predetermined level of signal, and converting the sum signal into a binarized signal; a latch circuit for latching the output signal from the binarization circuit with a conversion clock of the analog-to-digital conversion circuit or a clock with a frequency that is an integral multiple of a frequency of the conversion clock, and converting the output signal into a recording timing signal; a control signal generation circuit for generating a control signal for removing a residual signal component as a residual component of a recording signal included in the digitized wobble detection differential signal, based on the recording timing signal output from the latch circuit and the digitized wobble detection differential signal; a residual component removal circuit for removing the residual signal component included in the digitized wobble detection difference signal based on the control signal supplied from the control signal generation circuit, so as to extract a land pre-pit detection signal; and an address detection circuit for detecting the address information based on the land pre-pit detection signal output from the residual component removal circuit.