Rewritable optical recording medium and optical recording method

A recording method for a rewritable optical recording medium, which comprises:

• recording information on a rewritable optical recording medium by a plurality of record mark lengths and space lengths between record marks based on runlength limited (RLL) non-return-to-zero inverted (NRZI) modulation system;
• irradiating, between record marks, a laser beam having an erasing power Pe capable of crystallizing an amorphous phase to form spaces between record marks;
• when a time length of one record mark is represented by nT (where T is a reference clock period), for a record mark of n=2m (where m is an integer of at least 1), a time length (n−j)T (where j is a real number from −2.0 to 2.0) of the n=2m record mark is divided into m sections of αiT and βiT comprising α1T, β1T, α2T, β2T, . . . , αmT and βmT (provided that Σi(αi+βi)=n−j), and for a record mark of n=2m+1 (where m is an integer of at least 1), a time length (n−k)T (where k is a real number from −2.0 to 2.0) of the n=2m+1 record mark is divided into m sections of αi′T and βi′T comprising α1′T, β1′T, α2′T, β2′T, . . . , αm′T and βm′T (provided that Σi(αi′+βi′)=n−k), applying a laser beam having a constant writing power Pw sufficient to melt a recording layer within a time of αiT and αi′T (where i is an integer from 1 to m);
• applying a laser beam having a bias power Pb within a time of βiT and βi′T (where i is an integer from 1 to m);
• and further,
• when m≧3,
• for a record mark of n=2m, when a start time for an nT mark is represented by T0,
• (i) generating α1T after a delay time Td1T from T0, then,
• (ii) alternately generating within i=2 to m, βi−1T and αiT in this order, while βi−1+αi is between 1.8 and 2.2 (provided that at i=2 and/or i=m, βi−1+αi may be deviated from about 2 within a range of ±0.5, and when m≧4, βi−1 and αi take constant values βc and αc, respectively, within i=3 to m−1), and then,
• (iii) generating βmT, and
• for a record mark of n=2m+1, when a start time for an nT mark is represented by T0,
• (i) generating α1′T after a delay time Td1′T from T0, then,
• (ii) alternately generating within i=2 to m, βi−1′T and αi′T in this order, while βi−1′+αi′ is between 1.8 and 2.2 (provided that at i=2 and/or i=m, βi−1′+αi′ may be deviated from about 2 within a range of ±2, and when m≧4, βi−1′ and αi′ take constant values βc and αc, respectively, within i=3 to m−1), and then,
• (iii) generating βm′T, and
• with the same m, for a record mark of n=2m and a record mark of n=2m+1, Td1=Td1′, α1=α1′, β1=β1′ and αm≠αm′, and at least one set selected from (βm−1 and βm−1′) and (βmand βm′) takes different values.