REWRITABLE OPTICAL RECORDING MEDIUM AND OPTICAL RECORDING METHOD

• US 20070237060A1
• Filed: 03/12/2007
• Published: 10/11/2007
• Est. Priority Date: 02/13/2002
• Status: Active Grant

• Current Assignee: CMC Magnetics Corporation
• Original Assignee: Mitsubishi Kagaku Media Company Limited (Mitsubishi Chemical Holdings Corporation)
• Inventors: Okamuro, Akio, Hoshino, Hiroyuki, Ohno, Takashi, Kubo, Masae, Horie, Michikazu, Mizuno, Masaaki
• Granted Patent: US 7,858,167 B2
• Time in Patent Office: Days
• US Class Current: 369/275.100
• CPC Class Codes: G11B 2007/24312 group 14 elements (e.g. Si, Ge, Sn)
• CPC Class Codes: G11B 2007/24314 group 15 elements (e.g. Sb, Bi)
• CPC Class Codes: G11B 2007/24316 group 16 elements (i.e. chalcogenides, Se, Te)
• CPC Class Codes: G11B 7/0045 Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: G11B 7/00454 involving phase-change effects
• CPC Class Codes: G11B 7/0062 Overwriting strategies, e.g. recording pulse sequences with erasing level used for phase-change media
• CPC Class Codes: G11B 7/126 Circuits, methods or arrangements for laser control or stabilisation
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/243 comprising inorganic materials only, e.g. ablative layers
• CPC Class Codes: G11B 7/259 based on silver
• CPC Class Codes: G11B 7/26 Apparatus or processes specially adapted for the manufacture of record carriers
• CPC Class Codes: Y10T 428/21 Circular sheet or circular blank

Abstract

A rewritable optical recording medium including: a substrate having a guide groove formed thereon, a phase-change type recording layer, a portion in a crystalline state of the phase-change type recording layer corresponds to an unrecorded or erased state, and a portion in an amorphous state of the phase-change type recording layer corresponds to a recorded state, so that an amorphous mark corresponding to the recorded state is formed upon irradiation with a recording laser beam. The phase-change type recording layer contains Sb as a main component, and further contains Ge and/or Te, a content of Ge is from 1 atomic % to 30 atomic %, and a content of Te is from 10 atomic % to 30 atomic %, and in the phase-change type recording layer, Sb/Te is at least 4.5, and the atomic ratio of Ge to Te is from 1:3 to 1:20.

Claims

1. A rewritable optical recording medium comprising:

a substrate having a guide groove formed thereon;

a phase-change type recording layer, a portion in a crystalline state of the phase-change type recording layer corresponds to an unrecorded or erased state, and a portion in an amorphous state of the phase-change type recording layer corresponds to a recorded state, so that an amorphous mark corresponding to the recorded state is formed upon irradiation with a recording laser beam;

the phase-change type recording layer contains Sb as a main component, and further contains Ge and/or Te, a content of Ge is from 1 atomic % to 30 atomic %, and a content of Te is from 10 atomic % to 30 atomic %; and

in the phase-change type recording layer, Sb/Te is at least 4.5, and the atomic ratio of Ge to Te is from 1;

3 to 1;

20.

2. The rewritable optical recording medium according to claim 1, wherein the phase-change type recording layer is made of an alloy having, as a main component, a composition represented by Ge_y(Sb_xTe_1-x)₁₋

y (where 0.01≦

y≦

0.06 and 0.82≦

x≦

0.9), and

when the rewritable optical recording medium is subjected to initial crystallization by a laser beam, the initial crystallization is carried out by irradiating the laser beam so that the linear velocity of the optical recording medium to the laser beam is from 0.1 m/s to 3 m/s.

3. The rewritable optical recording medium according to claim 1, wherein the phase-change type recording layer is made of an alloy having, as a main component, a composition represented by M_zGe_y(Sb_xTe₁₋

x)<sub>1−

y−

z</sub> where 0.01≦

z≦

0.1, 0.01≦

y≦

0.06 and 0.82≦

x≦

0.9, and M represents at least one element selected from the group consisting of Ga and In.

4. The rewritable optical recording medium according to claim 1, wherein the Sb/Te ratio is within a range from 5.5 to 7.3.

5. The rewritable optical recording medium according to claim 1, wherein a thickness of the phase-change type recording layer is from 10 to 30 nm.

6. The rewritable optical recording medium according to claim 1, wherein the rewritable optical recording medium further has a reflective layer, and a sheet resistivity of the reflective layer is from 0.05Ω

/□

to 0.2Ω

/□

.

7. The rewritable optical recording medium according to claim 1, wherein each of a modulation m₁₁ and a reflectivity R_top in the crystalline state maintains at least 90% of its initial value, even after being held in an accelerated test environment at a temperature of 105°

C. for 3 hours.

12. A recording method for a rewritable optical recording medium, to be used for the rewritable optical recording medium as defined in claim 1, which comprises recording information by a plurality of record mark lengths and space lengths between record marks, the method comprising:

applying, between record marks, a laser beam having an erasing power Pe capable of crystallizing an amorphous phase to form spaces between record marks;

when the time length of one record mark is represented by nT (where T is the reference clock period), for a record mark of n=2m (where m is an integer of at least

     1), having a time length (n−

j)T (where j is a real number from −

2.0 to 2.0) divided into m sections of α

_iT and β

_iT comprising α

₁T, β

₁T, α

₂T, β

₂T, . . . , α

_mT and β

_mT (provided that Σ

_i(α

_i+β

_i)=n−

j), and for a record mark of n=2m+1 (where m is an integer of at least

     1), having a time length (n−

k)T (where k is a real number from −

2.0 to 2.0) divided into m sections of α

_i′

T and β

_i′

T comprising α

₁′

T, β

₁′

T, α

₂′

T, β

₂′

T, . . . , α

_m′

T and β

_m′

T (provided that Σ

_i(α

_i′

+β

_i′

)=n−

k), applying a laser beam having a constant writing power Pw sufficient to melt the recording layer within a time of α

_iT and α

_i′

T (where i is an integer from 1 to m); and

applying a laser beam having a bias power Pb within a time of β

_iT and β

_i′

T (where i is an integer of 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 α

₁T after a delay time T_d1T from T₀,

then,

(ii) within i=2 to m, alternately generating β

<sub>i−

1</sub>T and α

_iT in this order, while β

<sub>i−

1</sub>+α

_i is between 1.8 and 2.2 (provided that at i=2 and/or i=m, β

<sub>i−

1</sub>+α

₁ may be deviated from about 2 within a range of ±

0.5, and

when m≧

4, β

<sub>i−

1</sub> and α

_i take constant values β

c and α

c, respectively, within i=3 to m−

1), and then,

(iii) generating β

_mT, and

for a record mark of n=2m+1, when the start time for an nT mark is represented by T₀,

(i) generating α

₁′

T after a delay time T_d1′

T from T₀,

then,

(ii) within i=2 to m, alternately generating β

<sub>i−

1</sub>′

T and α

_i′

T in this order, while β

<sub>i−

1</sub>′

+α

_i′

is between 1.8 and 2.2 (provided that at i=2 and/or i=m, β

<sub>i−

1</sub>′

+α

_i′

may be deviated from 2 within a range of ±

2, and when m≧

4, β

<sub>i−

1</sub>′ and

α

_i′

take constant values β

c and α

c, respectively, within i=3 to m−

1), and then,

(iii) generating β

_m′

T, and

with the same m, for a record mark of n=2m and a record mark of n=2m+1, α

_m≠

α

_m′

, and at least one set selected from (T_d1, T_d1′

), (α

₁, α

₁′

), (β

₁, β

₁′

), (β

<sub>m−

1</sub> and β

<sub>m−

1</sub>′

) and (β

_m and β

_m′

) takes different values.

13. The recording method according to claim 12, wherein when m≧

3, with the same m, for a record mark of n=2m and a record mark of n=2m+1, α

_m≠

α

_m′ and

β

₁≠

β

₁′

, and at least one set selected from (T_d1, T_d1′

), (α

₁, α

₁′

), (β

<sub>m−

1</sub> and β

<sub>m−

1</sub>′

) and (β

_m and β

_m′

) takes different values.

14. The recording method according to claim 13, wherein the relation of α

_m and α

_m′

is made to be α

_m′

=α

_m+Δ

_m (where 0<

Δ

_m≦

1), and the relation of β

_m and β

_m′

is made to be β

₁′

=β

₁+Δ

₁ (where 0<

Δ

₁≦

1).

15. The recording method according to claim 13, wherein when m is at least 3, the relations of T_d1′

=T_d1, α

₁′

=α

₁, β

₁+α

₂=1.5 to 2.5, β

<sub>m−

1</sub>+α

_m=1.5 to 2.5, β

₁′

=β

₁+Δ

₁ (where 0<

Δ

₁≦

1), β

<sub>m−

1</sub>′

=β

<sub>m−

1</sub>+Δ

<sub>m−

1</sub> (where Δ

<sub>m−

1</sub>=0 to

     1), α

_m′

=α

_m+Δ

_m (where 0<

Δ

_m≦

1), Δ

_mm=Δ

<sub>m−

1</sub>+Δ

_m, 0<

Δ

_mm≦

1 and β

_m′

=β

_m+Δ

_m′

(where Δ

_m′

=0 to

     1), are satisfied, and when m is at least 3, T_d1, α

₁, β

₁, Δ

₁, α

c, β

<sub>m−

1</sub>, Δ

<sub>m−

1</sub>, α

_m, Δ

_m, β

_m and Δ

_m′

are constant irrespective of m.

16. The recording method according to claim 13, wherein when m=2, α

₁, α

₁′

, α

₂, α

₂′

, β

₂ and β

₂′

are made to be equal to α

₁, α

₁′

, α

_m, α

_m′

, β

m and β

_m′

in the case of any m where m is at least 3, respectively (provided that with respect to β

₂′

, the value may further be changed within a range of ±

0.5), β

₁ is made to be equal to either β

₁ or β

<sub>m−

1</sub> in the case of any m where m is at least 3, and β

₁′

is made to be equal to either β

₁′

or β

<sub>m−

1</sub>′

in the case of any m where m is at least 3.

17. The recording method according to claim 13, wherein when m is at least 3, at least one formula is satisfied among T_d1+α

₁=2, α

₁=α

c, β

₁+α

₂=2, β

<sub>m−

1</sub>+α

_m=2 and α

_m=α

c.

18. The recording method according to claim 17, wherein when m=2, at least one formula is satisfied among T_d1+α

₁=T_d1′

+α

₁′

=2, α

₁=α

₁′

=α

c, β

₁+α

₂=2 and α

₂=α

c.

19. The recording method according to claim 12, wherein the recording linear velocity is set to be a linear velocity of at most 32 times the reference linear velocity V₁=1.2 to 1.4 m/s, and EFM modulation information is recorded by a plurality of record mark lengths and space lengths between record marks, wherein the time length of one record mark is set to be nT (where n is an integer of from 3 to 11), the ratio of an erasing power Pe to a writing power Pw is set to be Pe/Pw=0.2 to 0.6, and a bias power Pb is set to be Pb≦

0.2Pe.

20. The recording method according to claim 12, wherein the recording linear velocity is set to be a linear velocity of at most 12 times the reference linear velocity V₁=3.49 m/s, and EFM+ modulation information is recorded by a plurality of record mark lengths and space lengths between record marks, wherein the time length of one record mark is set to be nT (where n is an integer of from 3 to 11 and 14), the ratio of an erasing power Pe to a writing power Pw is set to be Pe/Pw=0.2 to 0.6, and a bias power Pb is set to be Pb≦

0.2Pe.

21. The recording method according to claim 12, wherein the rewritable optical recording medium is a circular disk, and recording is carried out at a plurality of recording linear velocities while controlling the recording linear density to be constant so that it will be the same as in a disk CLV-recorded at 1-time reference velocity (i.e. 1.2 m/s to 1.4 m/s in the case of CD, and 3.49 m/s in the case of DVD), in the same disk plane, wherein the maximum linear velocity V_max among the recording linear velocities is 20-times velocity, 24-times velocity or 32-times velocity in the case of CD, and 6-times velocity, 8-times velocity, 10-times velocity or 12-times velocity in the case of DVD;

and α

_i=α

_imax (where i=1 to m) at the V_max is from 0.5 to 2, and α

_i′

=α

_imax′

(where i=1 to m) at the V_max is from 0.5 to 2, and α

_i and α

_i′

(where i=1 to m) are permitted to simply decrease as the linear velocity lowers.

22. The recording method according to claim 21, wherein when the minimum linear velocity V_min is 8-times velocity, 10-times velocity, 12-times velocity or 16-times velocity in the case of CD, and 2.5-times velocity, 3-times velocity, 4-times velocity or 5-times velocity in the case of DVD, T_d1+α

₁, T_d1′

+α

₁′

, β

<sub>i−

1</sub>+α

_i=2, and β

<sub>i−

1</sub>′

+α

_i′

=2 (where i=3 to m−

1) are, respectively, constant irrespective of the linear velocity within a linear velocity range of from the V_min to the V_max when m is at least 3.

23. The recording method according to claim 21, wherein at any linear velocity to be used, β

_m=0 to 2, and β

_m′

=0 to 3, and β

_m and β

_m′

are permitted to simply increase as the linear velocity lowers.

24. The recording method according to claim 21, wherein Δ

_m′

is permitted to simply increase as the linear velocity lowers.

25. The recording method according to claim 21, wherein among T_d1′

, α

₁′ and

β

₁′

where n=3, T_d1′ and

β

₁′

are permitted to simply increase as the linear velocity lowers, and α

₁′

is permitted to simply decrease as the linear velocity lowers.

26. The recording method according to claim 21, wherein at any linear velocity to be used, β

₁T (where i=1 to m) and β

₁′

T (where i=1 to m−

1) are at least 2 nsec.

27. The recording method according to claim 21, wherein when EFM modified information is recorded on the circular disk rewritable optical recording medium by a plurality of mark lengths, the optical recording medium is rotated so that the linear velocity at the outermost periphery of the record area of the optical recording medium, would be at least 20-times velocity, based on the reference linear velocity (1-time velocity) being a linear velocity of from 1.2 m/s to 1.4 m/s.

28. The recording method according to claim 27, wherein the disk is rotated so that the linear velocity at the innermost periphery of the record area would be at least 16-times velocity of the reference linear velocity, and the recording linear velocity becomes higher towards the outer periphery.

29. The recording method according to claim 27, wherein the record area is divided into a plurality of imaginary zones in every certain radius, and β

_m=0 to 3, and further, β

_m is made to simply increase towards the inner peripheral zone, and α

_i and α

_i′

are made to simply decrease towards the inner peripheral zone.

30. The recording method according to claim 27, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.

31. The recording method according to claim 21, wherein when EFM+ modified information is recorded on the circular disk rewritable optical recording medium by a plurality of mark lengths, the optical recording medium is rotated so that the linear velocity at the outermost periphery of the record region of the optical recording medium, would be at least 6-times velocity, based on the reference linear velocity (1-time velocity) being a linear velocity of 3.49 m/s.

32. The recording method according to claim 31, wherein the disk is rotated so that the linear velocity at the innermost periphery of the record region would be at least 6-times velocity of the reference linear velocity, and the recording linear velocity becomes higher towards the outer periphery.

33. The recording method according to claim 31, wherein the record region is divided into a plurality of imaginary zones in every certain radius, and β

_m=0 to 3, and further, β

_m is made to simply increase towards the inner peripheral zone, and α

_i and α

_i′

are made to simply decrease towards the inner peripheral zone.

34. The recording method according to claim 31, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.

8. A rewritable optical recording medium comprising:

a substrate having a guide groove formed thereon;

a phase-change type recording layer, a portion in a crystalline state of the phase-change type recording layer corresponds to an unrecorded or erased state, and a portion in an amorphous state of the phase-change type recording layer corresponds to a recorded state, so that an amorphous mark corresponding to the recorded state is formed upon irradiation with a recording laser beam;

the phase-change type recording layer contains Sb as a main component, and further contains Ge and/or Te, a content of Te is less than 10 atomic %, and a content of Ge is from 1 atomic % to 30 atomic %; and

the phase-change type recording layer is made of an alloy having, as a main component, a composition represented by Te_γ

M1_β

(Ge_α

Sb<sub>1−

α</sub>

)<sub>1−

β

−

γ</sub>

(where 0.01≦

α

≦

0.3, 0≦

β

≦

0.3, 0≦

γ

≦

0.1, 2≦

β

/γ and

0<

β

+γ

≦

0.4, and M1 represents one element selected from the group consisting of In, Ga and Sn.

9. The rewritable optical recording medium according to claim 8, wherein a thickness of the phase-change type recording layer is from 10 to 30 nm.

10. The rewritable optical recording medium according to claim 8, wherein the rewritable optical recording medium further has a reflective layer, and a sheet resistivity of the reflective layer is from 0.05Ω

/□

to 0.20Ω

/□

.

11. The rewritable optical recording medium according to claim 8, wherein each of a modulation m₁₁ and a reflectivity R_top in the crystalline state maintains at least 90% of an initial value, even after being held in an accelerated test environment at a temperature of 105°

C. for 3 hours.

35. A recording method for a rewritable optical recording medium, to be used for the rewritable optical recording medium as defined in claim 8, which comprises recording information by a plurality of record mark lengths and space lengths between record marks, the method comprising:

between record marks, applying a laser beam having an erasing power Pe capable of crystallizing an amorphous phase to form spaces between record marks;

when the time length of one record mark is represented by nT (where T is the reference clock period), for a record mark of n=2m (where m is an integer of at least

     1), having a time length (n−

j)T (where j is a real number from −

2.0 to 2.0) divided into m sections of α

_iT and β

_iT comprising α

₁T, β

₁T, α

₂T, β

₂T, . . . , α

_mT and β

_mT (provided that ρ

_i(α

_i+β

_i)=n−

j), and for a record mark of n=2m+1 (where m is an integer of at least

     1), having a time length (n−

k)T (where k is a real number from −

2.0 to 2.0) divided into m sections of α

_i′

T and β

_i′

T comprising α

₁′

T, β

₁′

T, α

₂′

T, β

₂′

T, . . . , α

_m′

T and β

_m′

T (provided that Σ

_i(α

_i′

+β

_i′

)=n−

k), applying a laser beam having a constant writing power Pw sufficient to melt the recording layer within a time of α

_iT and α

_i′

T (where i is an integer from 1 to m); and

applying a laser beam having a bias power Pb within a time of β

_iT and β

_i′

T (where i is an integer of 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 α

₁T after a delay time T_d1T from T₀,

then,

(ii) within i=2 to m, alternately generating β

<sub>i−

1</sub>T and α

_iT in this order, while β

<sub>i−

1</sub>+α

_i is between 1.8 and 2.2 (provided that at i=2 and/or i=m, β

<sub>i−

1</sub>+α

₁ may be deviated from about 2 within a range of ±

0.5, and

when m≧

4, β

<sub>i−

1</sub> and α

_i take constant values β

c and α

c, respectively, within i=3 to m−

1), and then,

(iii) generating β

_mT, and

for a record mark of n=2m+1, when the start time for an nT mark is represented by T₀,

(i) generating α

₁′

T after a delay time T_d1′

T from T₀,

then,

(ii) within i=2 to m, alternately generating β

<sub>i−

1</sub>′

T and α

_i′

T in this order, while β

<sub>i−

1</sub>′

+α

_i′

is between 1.8 and 2.2 (provided that at i=2 and/or i=m, β

<sub>i−

1</sub>′

+α

_i′

may be deviated from 2 within a range of ±

2, and when m≧

4, β

<sub>i−

1</sub>′ and

α

_i′

take constant values β

c and α

c, respectively, within i=3 to m−

1), and then,

(iii) generating β

_m′

T, and

with the same m, for a record mark of n=2m and a record mark of n=2m+1, α

_m≠

α

_m′

, and at least one set selected from (T_d1, T_d1′

), (α

₁, α

₁′

), (β

₁, β

₁′

), (β

<sub>m−

1</sub> and β

<sub>m−

1</sub>′

) and (β

_m and β

_m′

) takes different values.

36. The recording method according to claim 35, wherein when m≧

3, with the same m, for a record mark of n=2m and a record mark of n=2m+1, α

_m≠

α

_m′ and

β

₁≠

β

₁′

, and at least one set selected from (T_d1, T_d1′

), (α

₁, α

₁′

), (β

<sub>m−

1</sub> and β

<sub>m−

1</sub>′

) and (β

_m and β

_m′

) takes different values.

37. The recording method according to claim 36, wherein the relation of α

_m and α

_m′

is made to be α

_m′

=α

_m+Δ

_m (where 0<

Δ

_m≦

1), and the relation of β

_m and β

_m′

is made to be β

₁′

=β

₁+Δ

₁ (where 0<

Δ

₁≦

1).

38. The recording method according to claim 36, wherein when m is at least 3, the relations of T_d1′

=T_d1, α

₁′

=α

₁, β

₁+α

₂=1.5 to 2.5, β

<sub>m−

1</sub>+α

_m=1.5 to 2.5, β

₁′

=β

₁+Δ

₁ (where 0<

Δ

₁≦

1), β

<sub>m−

1</sub>′

=β

<sub>m−

1</sub>+Δ

<sub>m−

1</sub> (where Δ

<sub>m−

1</sub>=0 to

     1), α

_m′

=α

_m+Δ

_m (where 0<

Δ

_m≦

1), Δ

_mm=Δ

<sub>m−

1</sub>+Δ

_m, 0<

Δ

_mm≦

1 and β

_m′

=β

_m+Δ

_m′

(where Δ

_m′

=0 to

     1), are satisfied, and when m is at least 3, T_d1, α

₁, β

₁, Δ

₁, α

c, β

<sub>m−

1</sub>, Δ

<sub>m−

1</sub>, α

_m, Δ

_m, β

_m and Δ

_m′

are constant irrespective of m.

39. The recording method according to claim 36, wherein when m=2, α

₁, α

₁′

, α

₂, α

₂′

, β

₂ and β

₂′

are made to be equal to α

₁, α

₁′

, α

_m, α

_m′

, β

_m and β

_m′

in the case of any m where m is at least 3, respectively (provided that with respect to β

₂′

, the value may further be changed within a range of ±

0.5), β

₁ is made to be equal to either β

₁ or β

<sub>m−

1</sub> in the case of any m where m is at least 3, and β

₁′

is made to be equal to either β

₁′

or β

<sub>m−

1</sub>′

in the case of any m where m is at least 3.

40. The recording method according to claim 36, wherein when m is at least 3, at least one formula is satisfied among T_d1+α

₁=2, α

₁=α

c, β

₁+α

₂=2, β

<sub>m−

1</sub>+α

_m=2 and α

_m=α

c.

41. The recording method according to claim 40, wherein when m=2, at least one formula is satisfied among T_d1+α

₁=T_d1′

+α

₁′

=2, α

₁=α

₁′

=′

c, β

₁+α

₂=2 and α

₂=α

c.

42. The recording method according to claim 35, wherein the recording linear velocity is set to be a linear velocity of at most 32 times the reference linear velocity V₁=1.2 to 1.4 m/s, and EFM modulation information is recorded by a plurality of record mark lengths and space lengths between record marks, wherein the time length of one record mark is set to be nT (where n is an integer of from 3 to 11), the ratio of an erasing power Pe to a writing power Pw is set to be Pe/Pw=0.2 to 0.6, and a bias power Pb is set to be Pb≦

0.2Pe.

43. The recording method according to claim 35, wherein the recording linear velocity is set to be a linear velocity of at most 12 times the reference linear velocity V₁=3.49 m/s, and EFM+ modulation information is recorded by a plurality of record mark lengths and space lengths between record marks, wherein the time length of one record mark is set to be nT (where n is an integer of from 3 to 11 and 14), the ratio of an erasing power Pe to a writing power Pw is set to be Pe/Pw=0.2 to 0.6, and a bias power Pb is set to be Pb≦

0.2Pe.

44. The recording method according to claim 35, wherein the rewritable optical recording medium is a circular disk, and recording is carried out at a plurality of recording linear velocities while controlling the recording linear density to be constant so that it will be the same as in a disk CLV-recorded at 1-time reference velocity (i.e. 1.2 m/s to 1.4 m/s in the case of CD, and 3.49 m/s in the case of DVD), in the same disk plane, wherein the maximum linear velocity V_max among the recording linear velocities is 20-times velocity, 24-times velocity or 32-times velocity in the case of CD, and 6-times velocity, 8-times velocity, 10-times velocity or 12-times velocity in the case of DVD;

and α

_i=α

_imax (where i=1 to m) at the V_max is from 0.5 to 2, and α

_i′

=α

_imax′

(where i=1 to m) at the V_max is from 0.5 to 2, and α

_i and α

_i′

(where i=1 to m) are permitted to simply decrease as the linear velocity lowers.

45. The recording method according to claim 44, wherein when the minimum linear velocity V_min is 8-times velocity, 10-times velocity, 12-times velocity or 16-times velocity in the case of CD, and 2.5-times velocity, 3-times velocity, 4-times velocity or 5-times velocity in the case of DVD, T_d1+α

₁, T_d1′

+α

₁′

, β

<sub>i−

1</sub>+α

_i=2, and β

<sub>i−

1</sub>′

+α

_i′

=2 (where i=3 to m−

1) are, respectively, constant irrespective of the linear velocity within a linear velocity range of from the V_min to the V_max when m is at least 3.

46. The recording method according to claim 44, wherein at any linear velocity to be used, β

_m=0 to 2, and β

_m′

=0 to 3, and β

_m and β

_m′

are permitted to simply increase as the linear velocity lowers.

47. The recording method according to claim 44, wherein Δ

_m′

is permitted to simply increase as the linear velocity lowers.

48. The recording method according to claim 44, wherein among T_d1′

, α

₁′ and

β

₁′

where n=3, T_d1′ and

β

₁′

are permitted to simply increase as the linear velocity lowers, and α

₁′

is permitted to simply decrease as the linear velocity lowers.

49. The recording method according to claim 44, wherein at any linear velocity to be used, β

₁T (where i=1 to m) and β

₁′

T (where i=1 to m−

1) are at least 2 nsec.

50. The recording method according to claim 44, wherein when EFM modified information is recorded on the circular disk rewritable optical recording medium by a plurality of mark lengths, the optical recording medium is rotated so that the linear velocity at the outermost periphery of the record area of the optical recording medium, would be at least 20-times velocity, based on the reference linear velocity (1-time velocity) being a linear velocity of from 1.2 m/s to 1.4 m/s.

51. The recording method according to claim 50, wherein the disk is rotated so that the linear velocity at the innermost periphery of the record area would be at least 16-times velocity of the reference linear velocity, and the recording linear velocity becomes higher towards the outer periphery.

52. The recording method according to claim 50, wherein the record area is divided into a plurality of imaginary zones in every certain radius, and β

_m=0 to 3, and further, β

_m is made to simply increase towards the inner peripheral zone, and α

_i and α

_i′

are made to simply decrease towards the inner peripheral zone.

53. The recording method according to claim 50, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.

54. The recording method according to claim 44, wherein when EFM+ modified information is recorded on the circular disk rewritable optical recording medium by a plurality of mark lengths, the optical recording medium is rotated so that the linear velocity at the outermost periphery of the record region of the optical recording medium, would be at least 6-times velocity, based on the reference linear velocity (1-time velocity) being a linear velocity of 3.49 m/s.

55. The recording method according to claim 54, wherein the disk is rotated so that the linear velocity at the innermost periphery of the record region would be at least 6-times velocity of the reference linear velocity, and the recording linear velocity becomes higher towards the outer periphery.

56. The recording method according to claim 54, wherein the record region is divided into a plurality of imaginary zones in every certain radius, and β

_m=0 to 3, and further, β

_m is made to simply increase towards the inner peripheral zone, and α

_i and α

_i′

are made to simply decrease towards the inner peripheral zone.

57. The recording method according to claim 54, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.