Encoding device, encoding method, recording device, recording method, optical recording medium, decoding device and decoding method

A recording device for converting m-bit data words into n-bit (both n and m are integers and 2n≧2m×2) code words and performing recording with respect to an optical recording medium, comprising:

• a first encoding table in which 2m code words selected from the 2n n-bit code words correspond to 2m m-bit data words;
• a second encoding table in which 2m code words, which do not overlap with the code words in the first encoding table, of the 2n n-bit code words correspond to 2m m-bit data words;
• an encoding unit which selects and outputs a code word, in which an absolute value of a code string DSV is smaller, from code words corresponding to the input m-bit data words in the first encoding table and code words corresponding to the input m-bit data words in the second encoding table;
• and
• a recording unit which performs recording with respect to the optical recording medium based on the code words output from the encoding unit.

A decoding device comprising a decoding unit which includes first and second decoding tables in which code words and data words have the same correspondence as first and second encoding tables and which searches both a first decoding table and a second decoding table for m-bit data words corresponding to input n-bit code words and outputs the m-bit data words,

• in which the first and second encoding tables are used when converting the m-bit data words into the n-bit (both n and m are integers and 2n≧2m×2) code words,
• in the first encoding table, 2m code words selected from the 2n n-bit code words correspond to 2m m-bit data words,
• in the second encoding table, 2m code words, which do not overlap with the code words in the first encoding table, of the 2n n-bit code words correspond to 2m m-bit data words,
• code words in which the number of symbols “1” is an odd number in the second encoding table correspond to data words to which code words in which the number of symbols “1” is an even number correspond to the first encoding table,
• code words in which the number of symbols “1” is an even number in the second encoding table correspond to data words to which code words in which the number of symbols “1” is an odd number correspond to the first encoding table,
• in any one set of code words in which the number of symbols “1” is an even number in the first encoding table and a set of code words in which the number of symbols “1” is an odd number in the second encoding table, the code words are aligned in ascending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words, and, in the other of the sets, the code words are aligned in descending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words,
• in any one set of code words in which the number of symbols “1” is an odd number in the first encoding table and a set of code words in which the number of symbols “1” is an even number in the second encoding table, the code words are aligned in ascending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words, and, in the other of the sets, the code words are aligned in descending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words, and
• decoding is performed with respect to a code string obtained by performing an encoding process of selecting and outputting a code word, in which an absolute value of a code string DSV is smaller, from code words corresponding to the input m-bit data words in the first encoding table and code words corresponding to the input m-bit data words in the second encoding table.

A decoding method comprising the steps of searching both a first decoding table and a second decoding table, in which the code words and the data words having the same correspondence as first and second encoding tables, for m-bit data words corresponding to input n-bit code words and outputting the m-bit data words,

• in which the first and second encoding tables are used when converting the m-bit data words into the n-bit (both n and m are integers and 2n≧2m×2) code words,
• in the first encoding table, 2m code words selected from the 2n n-bit code words correspond to 2m m-bit data words,
• in the second encoding table, 2m code words, which do not overlap with the code words in the first encoding table, of the 2n n-bit code words correspond to 2m m-bit data words,
• code words in which the number of symbols “1” is an odd number in the second encoding table correspond to data words to which code words in which the number of symbols “1” is an even number correspond to the first encoding table,
• code words in which the number of symbols “1” is an even number in the second encoding table correspond to data words to which code words in which the number of symbols “1” is an odd number correspond to the first encoding table,
• in any one set of code words in which the number of symbols “1” is an even number in the first encoding table and a set of code words in which the number of symbols “1” is an odd number in the second encoding table, the code words are aligned in ascending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words, and, in the other of the sets, the code words are aligned in descending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words,
• in any one set of code words in which the number of symbols “1” is an odd number in the first encoding table and a set of code words in which the number of symbols “1” is an even number in the second encoding table, the code words are aligned in ascending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words, and, in the other of the sets, the code words are aligned in descending order of code word DSV when the code words are NRZ-converted so as to correspond to the data words,
• decoding is performed with respect to a code string obtained by performing an encoding process of selecting and outputting a code word, in which an absolute value of a code string DSV is smaller, from code words corresponding to the input m-bit data words in the first encoding table and code words corresponding to the input m-bit data words in the second encoding table.