Optical disc apparatus and optical disc reproduction method

Patent metadata

Field	Value
Publication number	US-2016284380-A1
Application number	US-201615172579-A
Country	US
Kind code	A1
Filing date	Jun 3, 2016
Priority date	Jan 17, 2014
Publication date	Sep 29, 2016
Grant date	—

Abstract

An optical disc apparatus includes a synchronizer that generates a reproduction clock signal synchronized with a reproduction signal of information recorded in an optical disc medium, and generates a digital reproduction signal synchronized with the reproduction clock signal, an adaptive equalizer that generates a post-adaptive-equalization digital reproduction signal, and a maximum likelihood decoder that performs maximum likelihood decoding of the post-adaptive-equalization digital reproduction signal to generate a binary signal. The apparatus also includes an expected waveform generator that generates an expected waveform from the binary signal, a phase-advance waveform generator that generates a phase-advance waveform, a phase-delay waveform generator that generates a phase-delay waveform, and a metric detector that detects a phase error. In the optical disc apparatus, the synchronizer controls the phase of the digital reproduction signal using the phase error.

First claim

1 . An optical disc apparatus that reproduces information recorded in an optical disc medium, the optical disc apparatus comprising:
a synchronizer that generates a reproduction clock signal synchronized with a reproduction signal obtained from the information, and generates a digital reproduction signal synchronized with the reproduction clock signal; an adaptive equalizer that shapes a waveform of the digital reproduction signal to generate a post-adaptive-equalization digital reproduction signal; a maximum likelihood decoder that performs maximum likelihood decoding of the post-adaptive-equalization digital reproduction signal to generate a binary signal; an expected waveform generator that generates an expected waveform from the binary signal having a time width of 2LT with respect to a time width of LT of an impulse response waveform of the digital reproduction signal; a phase-advance waveform generator that generates a phase-advance waveform in which a phase of the expected waveform is advanced by 1T; a phase-delay waveform generator that generates a phase-delay waveform in which the phase of the expected waveform is delayed by 1T; and a metric detector that detects a phase error between the reproduction signal and the reproduction clock signal based on a metric value calculated from each of the post-adaptive-equalization digital reproduction signal, the expected waveform, the phase-advance waveform, and the phase-delay waveform at an interval of ±(L/2)T from a center of the binary signal having the time width of 2LT, wherein the synchronizer controls a phase of the digital reproduction signal using the phase error.

2 . The optical disc apparatus according to claim 1 , wherein the synchronizer includes:
an oscillator that generates the reproduction clock signal synchronized with the reproduction signal obtained from the information; an A/D converter that generates the digital reproduction signal synchronized with the reproduction clock signal; and a loop filter that controls the reproduction clock signal using the phase error.

3 . The optical disc apparatus according to claim 1 , wherein the metric detector calculates the metric value except for a portion in which a difference between the post-adaptive-equalization digital reproduction signal and a signal value of the expected waveform is equal to or greater than a predetermined threshold.

4 . The optical disc apparatus according to claim 1 , wherein the metric detector calculates the metric value except for a portion in which a signal value of the expected waveform falls within a predetermined amplitude range and an amplitude continues for a predetermined time or more.

5 . The optical disc apparatus according to claim 1 , wherein the synchronizer includes:
a wobble detector that generates the reproduction clock signal from a wobble signal included in the reproduction signal obtained from the information; an A/D converter that generates the digital reproduction signal synchronized with the reproduction clock signal; a phase interpolation filter that corrects a phase deviation of the digital reproduction signal; a loop filter that generates a phase control value using the phase error to control the phase interpolation filter; and a phase interpolation coefficient selector that selects a filter coefficient of the phase interpolation filter based on the phase control value.

6 . An optical disc apparatus that reproduces information recorded in an optical disc medium, the optical disc apparatus comprising:
a synchronizer that generates a reproduction clock signal synchronized with a reproduction signal obtained from the information, and generates a digital reproduction signal synchronized with the reproduction clock signal; an adaptive equalizer that shapes a waveform of the digital reproduction signal to generate a post-adaptive-equalization digital reproduction signal; a maximum likelihood decoder that performs maximum likelihood decoding of the post-adaptive-equalization digital reproduction signal to generate a binary signal; a +1T delay unit that delays the binary signal by +1T to generate a +1T-delay binary data signal; a −1T delay unit that delays the binary signal by −1T to generate a −1T-delay binary data signal; and a cross-correlation detector that detects a cross-correlation phase error from a cross-correlation between the post-adaptive-equalization digital reproduction signal and the +1T-delay binary data signal and a cross-correlation between the post-adaptive-equalization digital reproduction signal and the −1T-delay binary data signal in a time width of LT of an impulse response waveform of the digital reproduction signal, the cross-correlation phase error indicating whether a phase in which the post-adaptive-equalization digital reproduction signal is sampled deviates forward or backward with respect to the binary signal, wherein the synchronizer controls a phase of the digital reproduction signal using the cross-correlation phase error.

7 . The optical disc apparatus according to claim 6 , wherein the synchronizer includes:
an oscillator that generates the reproduction clock signal synchronized with the reproduction signal obtained from the information; an A/D converter that generates the digital reproduction signal synchronized with the reproduction clock signal; and a loop filter that controls the reproduction clock signal using the cross-correlation phase error.

8 . The optical disc apparatus according to claim 6 , wherein the synchronizer includes:
a wobble detector that generates the reproduction clock signal from a wobble signal included in the reproduction signal obtained from the information; an A/D converter that generates the digital reproduction signal synchronized with the reproduction clock signal; a phase interpolation filter that corrects a phase deviation of the digital reproduction signal; a loop filter that generates a phase control value using the phase error to control the phase interpolation filter; and a phase interpolation coefficient selector that selects a filter coefficient of the phase interpolation filter based on the phase control value.

9 . An optical disc reproduction method for reproducing information recorded in an optical disc medium, the optical disc reproduction method comprising the steps of:
generating a post-adaptive-equalization digital reproduction signal by shaping a waveform of a digital reproduction signal produced from a reproduction signal obtained from the information in synchronization with a reproduction clock signal; performing maximum likelihood decoding of the post-adaptive-equalization digital reproduction signal to generate a binary signal; generating an expected waveform from the binary signal having a time width of 2LT with respect to a time width of LT of an impulse response waveform of the digital reproduction signal; generating a phase-advance waveform in which a phase of the expected waveform is advanced by 1T; generating a phase-delay waveform in which the phase of the expected waveform is delayed by 1T; detecting a phase error between the reproduction signal and the reproduction clock signal based on a metric value calculated from each of the post-adaptive-equalization digital reproduction signal, the expected waveform, the phase-advance waveform, and the phase-delay waveform at an interval of ±(L/2)T from a center of the binary signal having the time width of 2LT; and controlling a phase of the digital reproduction signal using the phase error.

10 . An optical disc reproduction method for reproducing information recorded in an optical disc medium, the optical disc reproduction method comprising the steps of:
generating a post-adaptive-

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Nakata Kohei
• Hino Yasumori

Classifications

• G11B20/10046

  filtering or equalising, e.g. setting the tap weights of an FIR filter · CPC title

• G11B20/10009

  Improvement or modification of read or write signals · CPC title

• G11B7/005

  Reproducing (G11B7/0065 takes precedence) · CPC title

• G11B7/0037

  with discs · CPC title

• G11B20/10222 Primary

  clock-related aspects, e.g. phase or frequency adjustment or bit synchronisation (dedicated sync patterns in the modulation code G11B20/1403) · CPC title