Optical disk recording method, optical disk device, and integrated circuit

An optical disk device which irradiates an optical disk with an optical beam to form a plurality of marks on a medium, and records information using edge positions of each mark and a space between two adjacent marks, comprising:

• an encoding unit configured to encode recording data according to modulation codes to generate binary encoded data corresponding to the mark and the space;
• a classification unit configured to, regarding run lengths of the mark and the space in the encoded data, if a mark of interest is target mark, classify the encoded data according to a combination of at least two run lengths of a mark length of the target mark, a space length of a preceding space on a preceding side of the target mark, a mark length of a preceding mark on the preceding side of the target mark, and a space length of a succeeding space on a succeeding side of the target mark;
• a correction amount setting unit configured to for each classification of the run length of the encoded data, set individual correction amounts for adjusting positions of a start edge and an end edge of a recording pulse for forming the mark, based on an evaluation index of a decoding result which is obtained when a reproduction signal obtained by reproducing the mark and space corresponding to the encoded data is decoded by maximum likelihood decoding of a PRML scheme;
• a recording waveform generating unit configured to generate a recording pulse according to the encoded data using the correction amount according to the classification of the run length of the encoded data;
• and
• a recording light output unit configured to form a mark according to the recording data on the medium of the optical disk by changing a power of the optical beam in a plurality of stages with the recording pulse and irradiating the optical disk with the optical beam, wherein
• the encoded data is generated by modulation codes having a maximum code length of 11T or more, and includes a code array having a minimum run length of 2T and a maximum run length of 11T or more,
• a constraint length, which is a class of the maximum likelihood decoding of the PRML scheme, is 11 or more,
• the evaluation index of the decoding result is an evaluation index by an extended L-SEAT operation in which an L-SEAT value representing a shift amount in a preceding or succeeding direction of a pattern in a predetermined range of a recording mark of interest is calculated using a binary bit array of the decoding result of the reproduction signal by the maximum likelihood decoding with the constraint length of 11 or more and at least one of a right-shift bit array and a left-shift bit array obtained by shifting the binary bit array by a single bit to right and left respectively,
• the classification unit performs, in the classification of the encoded data, the classification for each of run lengths 2T, 3T, 4T, 5T, 6T, 7T, and 8T or more according to the mark length of the target mark, and
• the correction amount setting unit sets the correction amount for each classification.

An integrated circuit which executes individual processes in an optical disk recording method for irradiating an optical disk with an optical beam to form a plurality of marks on a medium, and recording information using edge positions of each mark and a space between two adjacent marks, the processes comprising:

• encoding recording data according to modulation codes to generate binary encoded data corresponding to the mark and the space;
• regarding run lengths of the mark and the space in the encoded data, if a mark of interest is target mark, classifying the encoded data according to a combination of at least two run lengths of a mark length of the target mark, a space length of a preceding space on a preceding side of the target mark, a mark length of a preceding mark on the preceding side of the target mark, and a space length of a succeeding space on a succeeding side of the target mark;
• for each classification of the run length of the encoded data, setting individual correction amounts for adjusting positions of a start edge and an end edge of a recording pulse for forming the mark, based on an evaluation index of a decoding result which is obtained when a reproduction signal obtained by reproducing the mark and space corresponding to the encoded data is decoded by maximum likelihood decoding of a PRML scheme;
• generating a recording pulse according to the encoded data using the correction amount according to the classification of the run length of the encoded data;
• and
• forming a mark according to the recording data on the medium of the optical disk by changing a power of the optical beam in a plurality of stages with the recording pulse and irradiating the optical disk with the optical beam, wherein
• the encoded data is generated by modulation codes having a maximum code length of 11T or more, and includes a code array having a minimum run length of 2T and a maximum run length of 11T or more,
• a constraint length, which is a class of the maximum likelihood decoding of the PRML scheme, is 11 or more,
• the evaluation index of the decoding result is an evaluation index by an extended L-SEAT operation in which an L-SEAT value representing a shift amount in a preceding or succeeding direction of a pattern in a predetermined range of a recording mark of interest is calculated using a binary bit array of the decoding result of the reproduction signal by the maximum likelihood decoding with the constraint length of 11 or more and at least one of a right-shift bit array and a left-shift bit array obtained by shifting the binary bit array by a single bit to right and left respectively, and
• in the classification of the encoded data, the classification is performed for each of run lengths 2T, 3T, 4T, 5T, 6T, 7T, and 8T or more according to the mark length of the target mark, and the correction amount is set for each classification.