Optical disc signal processing apparatus, and medium having program recorded thereon for controlling optical disc apparatus
View Patent ↗An optical disc signal processing apparatus comprising: a binarizing circuit configured to compare a level of an RF (Radio Frequency) signal obtained by photoelectrically converting a reflected light of a laser beam applied to an optical disc and a level of a DC signal, to output a binarized signal for reproducing information recorded on the optical disc, a level of the DC signal being adjusted to a level at which jitter included in the binarized signal is minimized.
1. An optical disc signal processing apparatus including a binarizing circuit configured to compare a level of a reference signal and a level of an RF (Radio Frequency) signal which is obtained by photoelectrically converting a reflected light of a laser beam applied to the optical disc and on which a first DC signal is superimposed, to output a binarized signal for reproducing information recorded on an optical disc, the optical disc signal processing apparatus comprising:
a detecting circuit configured to detect jitter when a level of the DC signal is adjusted to a plurality of different levels, the jitter being fluctuation of the binarized signal on a time axis relative to a reproduction clock generated to be phase-locked to the binarized signal, the detecting circuit configured to charge and discharge a capacitor according to a phase difference between the binarized signal and the reproduction clock and to output a voltage on the capacitor as a first analog signal having a level corresponding to a magnitude of the jitter;
an AD converter configured to analog-digital convert the first analog signal and output a first digital signal;
a discriminating circuit configured to output a second digital signal for adjusting a level of the DC signal to the plurality of different levels within a certain range of levels when the first digital signal is input to the discriminating circuit, so as to discriminate the first digital signal for allowing the jitter to be minimized; and
a DA converter configured to digital-analog convert the second digital signal and output a second analog signal,
the binarizing circuit having a level of the DC signal set thereto according to the second analog signal corresponding to the first digital signal for allowing the jitter to be minimized.
2. An optical disc signal processing apparatus of claim 1 , wherein
the discriminating circuit outputs the second digital signal for adjusting a level of the DC signal to the plurality of different levels starting at a level at one side of the certain range of levels and progressively increasing or decreasing the second digital signal to a level at another side of the certain of levels, and wherein
the binarizing circuit having a level of the DC signal set thereto according to the second analog signal corresponding to the first digital signal when the jitter is minimized in a process for adjusting a level of the DC signal to the plurality of different levels.
3. An optical disc signal processing apparatus of claim 1 , wherein
the detecting circuit stops a jitter detecting operation when the discriminating circuit discriminates the first digital signal for allowing the jitter to be minimized.