Patent ID: 7345977

Claim:
A method of recording EFM-modulated information in terms of different mark lengths on a rewritable disc-shaped optical recording medium having a phase-change recording layer by CLV (constant linear velocity) operation, an individual recorded mark has a time length nT (T is the data reference clock period, and n is an integer within a range of from 3 to 11), and for recorded marks, the time length (n−j)T is divided into α 1 T, β 1 T, α 2 T, β 2 T, . . . , α m T, β m T (where m=n−1 or m=n−2) in this sequence so as to satisfy Σ i (α i +β i )=n−j (j is a real number within a range of 0.0≦j≦2.0), said method comprising the steps of: irradiating inter-mark portions with a recording light of erasure power Pe, which is able to crystallize an amorphous-state portion; irradiating the recording layer with a recording light of recording power Pw (Pw>Pe), which is able to melt the recording layer within the time length α i T (1≦i≦m); and irradiating the recording layer with a recording light of bias power Pb (0<Pb≦0.5Pe) within the time length β i T (1≦i≦m) to overwrite; and wherein when a linear velocity within a range of 1.2 m/s to 1.4 m/s is the reference velocity (1-times velocity) and 231 nsec (ns) is a reference clock period, (1) for the 4-times velocity, α 1 =from 0.3 to 1.5, α i =from 0.2 to 0.7 (2≦i≦m), α i +β i-1 =from 1 to 1.5 (3≦i≦m), (2) for the 1- or the 2-times velocity, α 1 =from 0.05 to 1.0, α i =from 0.05 to 0.5 (2≦i≦m), α i +β i-1 =from 1 to 1.5 (3≦i≦m) and (3) for any of 6-, 8-, 10- and 12-times velocities, α 1 =from 0.3 to 2, α i =from 0.3 to 1 (2≦i≦m), α i +β i-1 =from 1 to 1.5 (3≦i≦m), wherein for any of the described linear velocity in use, each of α 1 T, α i T (wherein i=2 to m), and α i +β i-1 is constant (where i is an integer within a range of from 3 to m); wherein for any of the described linear velocity in use, β m =from 0 to 1.5, and β m is constant for every linear velocity, or decreases as the linear velocity increases.