Reproducing apparatus for optical disc recorded in high density
AssigneeVictor Company of Japan, Ltd.
InventorsAtsushi Hayami, Junichiro Tonami
Life of this patent
Estimating the term…
Abstract
A resampling DPLL estimates a signal outputted from a pickup through an AGC and outputs a signal of the estimation result. A transversal filter in an adaptive equalizing circuit equalizes in waveform the signal outputted from the resampling DPLL. An error signal is detected from the equalized waveform outputted from the transversal filter. The error signal is fed back to the transversal filter so as to control the transversal filter such that the error signal becomes minimum.
Claims10
An optical disc reproducing apparatus for reproducing digital information from an optical disc medium in which the information is modulated and recorded in a recording track formed coaxially or spirally according to a signal modulation method for restricting run length such that a recording mark is 0.32 μm or more to less than 0.38 μm in track pitch and 0.12 μm or more to less than 0.22 μm in mark length, comprising:
- laser beam source for emitting laser beam having wavelength of 390 to 440 nm;
- a reflection light detecting means for detecting a reflection light produced when the laser beam emitted from the laser beam source is reflected by the optical disc medium to read a signal from the optical disc medium, so as to reproduce the information recorded in the optical disc medium;
- a digital phase synchronizing means for receiving a supply of signal outputted from the reflection light detecting means and digitally synchronizing phase so as to detect a phase at a data point phase and estimate digital data at the data point and outputting the digital data;
- an adaptive equalizing means including a transversal filter for equalizing in terms of waveform, the digital data outputted from the digital phase synchronizing means based on a filter coefficient, a temporary determining/subtracting circuit for while a sample after the waveform equalization outputted from the transversal filter is inputted therein, computing a temporary determining value for partial response equalization by comparing the sample with at least one threshold and outputting a differential between the temporary determining value and the sample after the waveform equalization as an error signal, and a coefficient control circuit for variably controlling a tap coefficient of the transversal filter so that the error signal becomes minimum;
- and
- a viterbi decoding means for viterbi-decoding a sample outputted from the adaptive equalizing means.
An optical disc reproducing apparatus for reproducing digital information from an optical disc medium in which the information is modulated and recorded in a recording track formed coaxially or spirally according to a signal modulation method for restricting run length such that a recording mark is 0.32 μm or more to less than 0.38 μm in track pitch and 0.12 μm or more to less than 0.22 μm in mark length, comprising:
- laser beam source for emitting laser beam having wavelength of 390 to 440 nm;
- a first reflection light detecting means for detecting a reflection light produced when the laser beam emitted from the laser beam source is reflected by the optical disc medium to read a signal from the optical disc medium, so as to reproduce the information recorded in the optical disc medium;
- a second reflection light detecting means for reading information separately from each of at least one pair of recording tracks on both sides of the recording track;
- a digital phase synchronizing means for while a signal outputted from the first reflection light detecting means is supplied thereto, digitally synchronizing phase so as to detect a phase at a data point and estimate digital data at the data point and outputting the digital data;
- a resampling means for while a signal outputted from the second reflection light detecting means is supplied thereto, resampling a signal from at least one recording track of the at least one pair of the recording tracks at the data point in the digital phase synchronizing means;
- an adaptive equalizing means including a first transversal filter for equalizing in terms of waveform, the digital data outputted from the digital phase synchronizing means based on a first filter coefficient, a temporary determining/subtracting circuit for while a sample after the waveform equalization outputted from the first transversal filter is inputted therein, computing a temporary determining value for partial response equalization by comparing the sample with at least one threshold and outputting a differential between the temporary determining value and the sample after the waveform equalization as an error signal, a second transversal filter for equalizing in waveform, the digital data outputted from the resampling means based on a second filter coefficient and generating a pseudo cross-talk signal based on an inputted tap coefficient, a subtracting means for subtracting the pseudo cross-talk signal from the sample after the waveform equalization, and a coefficient control circuit for variably controlling the tap coefficient inputted to the first and second transversal filters so that the error signal becomes minimum;
- and
- a viterbi decoding means for viterbi-decoding a sample outputted from the adaptive equalizing means.
Dependencies are inferred from the claim text.