Information storage medium evaluation method, information storage medium evaluation apparatus, information storage medium, information reproduction apparatus, information reproduction method, and information recording method

Abstract

An information storage medium according to an aspect of this invention has an information storage area for storing information, and a wobbled track which is used to guide a light beam on the information storage area, and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information. The wobbled track is formed so that an evaluation result based on the frequency characteristics of a squared reproduction signal obtained by squaring a reproduction signal corresponding to the wobbled track, obtained from the reflected light of a light beam with which the wobbled track is irradiated, meets a predetermined evaluation measure.

1 - 10 . (canceled) 
   
   
       11 . An information storage medium evaluation apparatus for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 a detection unit configured to detect reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   a filter unit configured to suppress noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light detected by the detection unit;   a squaring unit configured to square the reproduction signal from which the noise is suppressed by the filter unit; and   an evaluation unit configured to evaluate quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal squared by the squaring unit,   wherein when the squaring unit squares a predetermined sine wave and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluation unit is configured to set a residual peak level corresponding to a residual level of the predetermined frequency obtained from the frequency characteristics of the squared sine wave to be lower by not less than 30 dB than a peak level that appears at the frequency twice the predetermined frequency, and   the filter unit has a frequency band six times or more a carrier frequency of the reproduction signal.   
   
   
       12 . An information storage medium evaluation apparatus for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 a detection unit configured to detect reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   a filter unit configured to suppress noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light detected by the detection unit;   a squaring unit configured to square the reproduction signal from which the noise is suppressed by the filter unit; and   an evaluation unit configured to evaluate quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal squared by the squaring unit,   wherein when the squaring unit squares a predetermined sine wave and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluation unit is configured to set a residual peak level corresponding to a residual level of the predetermined frequency obtained from the frequency characteristics of the squared sine wave to be lower by not less than 30 dB than a peak level that appears at the frequency twice the predetermined frequency, and   when a difference between peak and noise levels obtained from the frequency characteristics of the squared reproduction signal becomes not less than 17 dB, the evaluation unit determines that the quality of the wobbled track meets a predetermined standard.   
   
   
       13 . An information storage medium evaluation apparatus for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 a detection unit configured to detect reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   a filter unit configured to suppress noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light detected by the detection unit;   a squaring unit configured to square the reproduction signal from which the noise is suppressed by the filter unit; and   an evaluation unit configured to evaluate quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal squared by the squaring unit,   wherein when the squaring unit multiplies a predetermined sine wave containing a noise component and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluation unit is configured to set a difference between a first difference between peak and noise levels obtained from the frequency characteristics of the sine wave and a second difference between peak and noise levels obtained from the frequency characteristics of the squared sine wave to be not more than 7 dB, and   the filter unit has a frequency band six times or more a carrier frequency of the reproduction signal.   
   
   
       14 . An information storage medium evaluation apparatus for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 a detection unit configured to detect reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   a filter unit configured to suppress noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light detected by the detection unit;   a squaring unit configured to square the reproduction signal from which the noise is suppressed by the filter unit; and   an evaluation unit configured to evaluate quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal squared by the squaring unit,   wherein when the squaring unit multiplies a predetermined sine wave containing a noise component and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluation unit is configured to set a difference between a first difference between peak and noise levels obtained from the frequency characteristics of the sine wave and a second difference between peak and noise levels obtained from the frequency characteristics of the squared sine wave to be not more than 7 dB, and   when a difference between peak and noise levels obtained from the frequency characteristics of the squared reproduction signal becomes not less than 17 dB, the evaluation unit determines that the quality of the wobbled track meets a predetermined standard.   
   
   
       15 . An information storage medium evaluation method for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 detecting reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   suppressing noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light;   squaring the reproduction signal from which the noise is suppressed; and   evaluating quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal,   wherein when the squaring process squares a predetermined sine wave and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluating process is configured to set a residual peak level corresponding to a residual level of the predetermined frequency obtained from the frequency characteristics of the squared sine wave to be lower by not less than 30 dB than a peak level that appears at the frequency twice the predetermined frequency, and   the suppressing process has a frequency band six times or more a carrier frequency of the reproduction signal.   
   
   
       16 . An information storage medium evaluation method for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 detecting reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   suppressing noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light;   squaring the reproduction signal from which the noise is suppressed; and   evaluating quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal,   wherein when the squaring process squares a predetermined sine wave and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluating process is configured to set a residual peak level corresponding to a residual level of the predetermined frequency obtained from the frequency characteristics of the squared sine wave to be lower by not less than 30 dB than a peak level that appears at the frequency twice the predetermined frequency, and   when a difference between peak and noise levels obtained from the frequency characteristics of the squared reproduction signal becomes not less than 17 dB, it is determined that the quality of the wobbled track meets a predetermined standard.   
   
   
       17 . An information storage medium evaluation method for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 detecting reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   suppressing noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light;   squaring the reproduction signal from which the noise is suppressed; and   evaluating quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal,   wherein when the squaring process multiplies a predetermined sine wave containing a noise component and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluating process is configured to set a difference between a first difference between peak and noise levels obtained from the frequency characteristics of the sine wave and a second difference between peak and noise levels obtained from the frequency characteristics of the squared sine wave to be not more than 7 dB, and   the suppressing process has a frequency band six times or more a carrier frequency of the reproduction signal.   
   
   
       18 . An information storage medium evaluation method for evaluating an information storage medium, which comprises a wobbled track that is used to guide a light beam and is wobbled in correspondence with a frequency, a phase of which is modulated at predetermined timings to reflect predetermined information, comprising:
 detecting reflected light of a light beam with which the wobbled track formed on the information storage medium is irradiated;   suppressing noise from a reproduction signal corresponding to the wobbled track on the basis of the reflected light;   squaring the reproduction signal from which the noise is suppressed; and   evaluating quality of the wobbled track on the basis of frequency characteristics of the squared reproduction signal,   wherein when the squaring process multiplies a predetermined sine wave containing a noise component and outputs the squared sine wave, a peak level at a predetermined frequency obtained from frequency characteristics of the sine wave appears at a frequency twice the predetermined frequency in frequency characteristics of the squared sine wave,   the evaluating process is configured to set a difference between a first difference between peak and noise levels obtained from the frequency characteristics of the sine wave and a second difference between peak and noise levels obtained from the frequency characteristics of the squared sine wave to be not more than 7 dB, and   when a difference between peak and noise levels obtained from the frequency characteristics of the squared reproduction signal becomes not less than 17 dB, it is determined that the quality of the wobbled track meets a predetermined standard.