Rewritable optical recording medium, recording method on the same, and optical disc recording/retrieving apparatus

A rewritable optical recording medium comprising a substrate having a wobble groove, and a phase-change recording layer, wherein a crystal state of the recording layer is an unrecorded or erased state and an amorphous state of the recording layer is a recorded state, and amorphous marks corresponding to the recorded state are formed by recording light

• after an EFM-modulated signal is recorded by an overwriting operation ten times in the recording layer at a 10-times velocity V as high as 10 times of a reference velocity (1-times velocity) V1, which is a linear velocity of 1.2 m/s, with a data reference clock period T retained so as to satisfy VT=V1T1 (where T1 is 231 ns) under one selected from various conditions of the following recording method 1′,
• a modulation m11 of an eye pattern of the recorded signal obtained as retrieved at the 1-times velocity is 60-80%,
• a topmost level Rtop of reflectivity of the eye pattern of the recorded signal obtained as retrieved at the 1-times velocity is 15-25%, and
• a jitter of the individual length of amorphous marks and inter-marks obtained as retrieved at the 1-times velocity are equal to or less than 35 ns;
• and
• said recording method 1′ is carried out by exposing the recording layer to recording light of a 780 nm wavelength via an optical system whose numerical aperture (NA) is 0.55 or 0.5, with the time length of the individual amorphous mark being nT (n is an integer within a range of from 3 to 11), in the following manner:
• during that time, erasure power Pe, which is able to crystallize the individual amorphous-state portions, irradiates inter-mark portions between the individual recorded marks,
• for the recorded marks, the time length (n−j)T is divided into α1T, β1T, α2T, β2T, . . . αmT, βmT (where m=n−1, α1=1.0, αi32 0.5 (i is an integer within a range of from 2 to m), βm=from 0.25 to 0.75, αi+βi−1=1.0 (i is an integer within a range of from 2 to m)) in this sequence so as to satisfy Σi(αi+βi)=n−j (j is a real number within a range of from 0 to 2.0),
• within the time length αiT (i is an integer within a range of from 1 to m), the recording light, whose record power Pw is enough to melt said recording layer, irradiates the recording layer (where Pw is 14 to 25 mW and Pe/Pw=0.5), and
• within the time length βiT (i is an integer within a range of from 1 to m), the recording light of bias power Pb of 0.8 mW irradiates the recording layer.

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, said method being carried out in the following manner:

• when 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),
• recording light of erasure power Pe, which is able to crystallize an amorphous-state portion, irradiates inter-mark portions,
• for the recorded marks, the time length (n−j)T is divided into α1T, β1T, α2T, β2T, . . . , αmT, βmT (where m=n−1 or m=n−2) in this sequence so as to satisfy Σi(αi+βi)=n−j (1 is a real number within a range of 0.0≦j≦2.0), and
• the recording light of recording power Pw (Pw>Pe), which is able to melt the recording layer within the time length αiT (1≦i≦m), irradiates the recording layer, and the recording light of bias power Pb (0<Pb≦0.5Pe) within the time length βiT (1≦i≦m) the recording layer to overwrite;
• and
• 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, α1=from 0.3 to 1.5, αi=from 0.2 to 0.7 (2≦i≦m), αi+βi−1=from 1 to 1.5 (3≦i≦m),
• (2) for the 1- or the 2-times velocity, α1=from 0.05 to 1.0, αi=from 0.05 to 0.5 (2≦i≦m), αi+βi−1=from 1 to 1.5 (3≦i≦m), and
• (3) for any of 6-, 8-, 10- and 12-times velocities, α1=from 0.3 to 2, αi=from 0.3 to 1 (2≦i≦m), αi+βi−1=from 1 to 1.5 (3≦i≦m).

A method of recording various mark and inter-mark lengths in terms of EFM-modulated information on a rewritable disc-shaped optical recording medium having a predetermined recording area by CAV (constant angular velocity) operation, in which the recording medium is rotated at a constant angular velocity, said method being carried out in the following manner:

• when a linear velocity within a range of from 1.2 m/s to 1.4 m/s is a reference velocity (1-times velocity), the disc-shaped optical recording medium is rotated in a way that a linear velocity at an outermost periphery of the recording area is as high as 10 times of the reference velocity,
• if a time length of an individual recorded mark is nT (T is a data reference clock period varying according to its radial position in a way that a product VT (V is a linear velocity in the radial position) is constant, and n is an integer within a range of from 3 to 11),
• recording light of erasure power Pe, which is able to crystallize an amorphous-state portion, irradiates inter-mark portions,
• for the recorded marks, the time length (n−j)T is divided into α1T, β1T, α2T, β2T, . . . , αmT, βmT (where m=n−1, α1=from 0.75 to 1.25, αi=from 0.25 to 0.75 (2≦i≦m), αi+βi−1=from 1 to 1.5 (3≦i≦m)) in this sequence so as to satisfy Σi(αi+βi)=n−j (j is a real number within a range of 0.0≦j≦2.0),
• within the time length αiT (1≦i≦m), the recording light, whose record power Pw (Pw>Pe) is enough to melt said recording layer, irradiates the recording layer, and within the time length βiT (1≦i≦m), the recording light of bias power Pb (0<Pb≦0.5Pe) irradiates the recording layer, and
• each of αi and αi+βi−1 (i=from 3 to m) is constant for any radial position, and βi (i=from 3 to m) is reduced monotonically for the radially inner position.

A method of recording various mark and inter-mark lengths in terms of EFM-modulated information on a rewritable disc-shaped optical recording medium having a predetermined recording area by CAV (constant angular velocity) operation, in which the recording medium is rotated at a constant angular velocity, said method being carried out in the following manner:

• when a linear velocity within a range of from 1.2 m/s to 1.4 m/s is a reference velocity (1-times velocity), the disc-shaped optical recording medium is rotated in a way that a linear velocity at an outermost periphery of the recording area is as high as to times of the reference velocity,
• if a time length of an individual recorded mark is nT (T is a data reference clock period varying according to its radial position in a way that a product VT (V is a linear velocity in the radial position is constant, and n is an integer within a range of from 3 to 11),
• recording light of erasure power Pe, which is able to crystallize an amorphous-state portion, irradiates inter-mark portions,
• for the recorded marks, the time length (n−j)T is divided into α1T, β1T, α2T, β2T, . . . αmT, βmT (where m=n−1, α1/αi=from 0.3 to 0.7 (i is an integer within a range of from 2 to m), αi+βi−1=approximately 1 (3≦i≦m) in this sequence so as to satisfy Σi(αi+βi)=n−j (j is a real number within a range of 0.0≦j≦2.0),
• within the time length αiT (1≦i≦m), the recording light, whose record power Pw (Pw>Pe) is enough to melt said recording layer, irradiates the recording layer, and within the time length βiT (1≦i≦m), the recording light of bias power Pb (0<Pb≦0.5Pe) irradiates the recording layer, and
• each of αiT (i=from 2 to m) and αi+βi−1 (i=from 3 to m) is constant for any radial position.

An optical disc recording/retrieving apparatus comprising:

• a motor for rotating a disc, which has a spiral groove with wobble which carrier frequency is constant in space frequency and meandering according to a signal modulated with a constant carrier frequency fL0 and address information and also has a recording layer, at a constant angular velocity with a center of the disc being an axis of rotation, the disc having address information identifying each recording data block, which is a unit of recording information located at a specified position in the spiral groove, and a synchronization pattern identifying a head position of the recording data block;
• an optical pick-up for generating a focused laser beam irradiating the disc for recording/retrieving;
• a linear motor for moving said optical pick-up radially of the disc to a given address;
• a focus servo circuit for focusing the focused laser beam on the recording layer;
• a groove tracking servo circuit for scanning the spiral groove by the focused laser beam;
• a detector and decoder circuit for detecting and decoding a carrier frequency fA0, address information and block synchronization signal from the meandering groove geometry;
• a data-sequence generation circuit for generating a recording data sequence, which is modulated in terms of mark length modulation, in synchronism with a data reference clock T which has a frequency fd0 and a start position of the recording block;
• a laser-power modulation circuit for modulating a recording laser power in accordance with the recording data sequence;
• a reference signal generator for generating a data reference clock T which varies in reverse proportion to a radius position when the focused laser beam is moved radially of the disc to a given address recording block;
• and
• a data-sequence synchronization circuit for synchronizing a data sequence, which is to be written in the given recording block, with the start position of the recording block by comparing in phase between a reference signal fR0, which is obtained by dividing the data reference clock at a particular radius by N(N is an integer), and the carrier frequency fA0, which is detected at the given address from the meandering groove geometry, and also making a fine adjustment of r.p.m. (revolutions per minute) of the disc so as to satisfy a relation fd0=N·fA0.

A recording/retrieving apparatus for performing recording and retrieving on a rewritable optical recording medium having an application area that includes an application program area occupying a continuous specified part of the application area and storing a predetermined application program, and a user data area which occupies the remaining portion of the application area and in which user data relating to at least the application program is adapted to be recorded, the application program and the user data being recorded in fixed-length packet units each having a common file management structure for both the application program and the user data, and retrieving of the application program and recording of the user data relating to the application program being made each at a constant angular velocity (CAV), said apparatus comprising:

• program executing means for executing the application program content by having access to the specified part of the application program in the rewritable optical recording medium to retrieve the application program data with keeping the medium, which is in the form of a disc, in CAV rotation at a first predetermined angular velocity;
• information input means for inputting necessary information according to the application program to be executed by said program executing means;
• and
• recording means for having access to the user data area with keeping the disc in CAV rotation at a second predetermined angular velocity and for recording in the user data area the necessary information, which is inputted by said information input means, as user data.