Claims
- 1. An optical recording method for recording mark length-modulated information with a plurality of recording mark lengths by irradiating a recording medium with a light, the optical recording method comprising the steps of:when a time length of one recording mark is denoted nT (T is a reference clock period equal to or less than 25 ns, and n is a natural number equal to or more than 2), dividing the time length of the recording mark nT into η1T, α1T, β1T, α2T, β2T, . . . , α1T, β1T, . . . , αmT, βmT, η2T in that order (m is a pulse division number; Σi(αi+βi)+η1+η2=n; αi (1≦i≦m) is a real number larger than 0; βi (1≦i≦m−1) is a real number larger than 0; βm is a real number larger than or equal to 0; and η1 and η2 are real numbers between −2 and 2); radiating recording light with a recording power Pwi in a time duration of αiT (1≦i≦m); and radiating recording light with a bias power Pbi in a time duration of βiT (1≦i≦m−1), the bias power being Pbi<Pwi and Pbi<Pwi+1; wherein the pulse division number m is 2 or more for the time duration of at least one recording mark and meets n/m≧1.25 for the time length of all the recording marks.
- 2. An optical recording method according to claim 1, wherein βi (1≦i≦m−1) is 0.5 to 2.5.
- 3. An optical recording method according to claim 1, wherein for the time length of all the recording marks, an average of αiT (1≦i≦m) is 3 nanoseconds or more and an average of βiT (1≦i≦m−1) is 3 nanoseconds or more.
- 4. An optical recording method according to claim 1, wherein for the time length of all the recording marks, αiT≧3 nanoseconds (1≦i≦m) and βiT≧3 nanoseconds (1≦i≦m−1) for each i.
- 5. An optical recording method according to claim 1, wherein for the time length of all the recording marks, n/m≧1.5 is met.
- 6. An optical recording method according to claim 1 , wherein αi+β1 (2≦i≦m−1) or βi−1+αi (2≦i≦m−1) takes a value of either 1.5, 2 or 2.5.
- 7. An optical recording method according to claim 6, wherein αi+βi (2≦i≦m−1) or βi−1+αi (2≦i≦m−1) is kept constant independently of a real number i.
- 8. An optical recording method according to claim 7, wherein αi+βi (2≦i≦m−1) or βi−1+αi (2≦i≦m−1) takes a value of 2 independently of a real number i, further wherein αi=αc with respect to any one of i in a range of 2≦i≦m−1, said αc being a constant value.
- 9. An optical recording method according to claims 7 or 8, wherein αi (2≦i≦m−1) is kept constant in the time length of the recording mark with having a pulse division number m being at least 3.
- 10. An optical recording method according to claim 1, wherein for at least two recording marks with different n's, the same pulse division number m is used and, at least one of αi (1≦i≦m), βi (1≦i≦m), η1, η2, Pwi (1≦i≦m) and Pb1 (1≦i≦m) is different from any one of said at least two recording marks.
- 11. An optical recording method according to claim 10, whereinwhen the mark length is expressed as nT=2LT (L is an integer equal to or larger than 2), the mark is divided into a division number m=L of sections and αi and βi in recording pulse sections αiT and off pulse sections β1T (these can change according to a value of L) are defined as follows: α1+β1=2+δ1 αi+βi=2 (2≦i≦m−1) αm+βm=2+δ2 (where δ1 and δ2 are real numbers satisfying −0.5≦δ1≦0.5 and −1≦δ2≦1 respectively; and when L=2, only α1, β1, αm and βm exist); when the mark length is expressed as nT=(2L+1)T, the mark is divided into a division number m=L of sections and αi′ and βi′ in recording pulse sections αi′T and off pulse sections βi′T (these can change according to a value of L) are defined as follows: α1′+β1′=2.5+δ1′αi′+βi′=2 (2≦i≦m−1) αm′+βm′=2.5+δ2′(where δ1′ and δ2′ are real numbers satisfying −0.5≦δ1′≦0.5 and −1≦δ2′≦1 respectively; and when L=2, only α1′, β1′, αm′ and βm′ exist); and α1, β1, αm, βm, α1′, β1′, αm′ and βm′ satisfy the following equation α1+β1+αm+βm+Δ=α1′+β1′+αm′+βm′(where Δ=0.8 to 1.2).
- 12. An optical recording method according to claim 11, wherein α1, β1, α1′ and β1′ satisfy the following equation:α1+β1+Δ1 =α1′+β1′(where Δ1=0.4 to 0.6).
- 13. An optical recording method according to claim 11, wherein in recording a mark with the mark length of nT=2T or 3T, the mark is divided into a division number m=1 of sections.
- 14. An optical recording method according to claim 11, wherein when L is larger than 3, αi is held constant at αi=αc and αi′ is held constant at αi′=αc′ for 2≦i≦m−1.
- 15. An optical recording method according to claim 14, wherein when L is larger than 3, αc and αc′ are constant, not dependent on L.
- 16. An optical recording method according to claim 14, wherein when L is larger than 3, αc=αc′.
- 17. An optical recording method according to claim 11, wherein when L is larger than 3, each of Td1, Td1′, α1, α1′, β1, β1′ takes a constant value.
- 18. An optical recording method according to claim 11, wherein when L is larger than 3, each of αm, αm′, βm and βm′ takes a constant value.
- 19. An optical recording method according to claim 11, wherein by using a first reference clock 1 with a period of T and a second reference clock 2 with a period of T, which is shifted 0.5T from the first reference clock, αi (1≦i≦m) is generated in synchronism with a reference clock 3 with a period of 2T that is produced by dividing the reference clock 1, and αi′ (2≦i≦m−1) is generated in synchronism with a reference clock 4 with a period of 2T that is produced by dividing the reference clock 2.
- 20. An optical recording method according to claim 11, whereinfor all L, a delay time Td1 with respect to a front end of a mark length to be recorded is provided at rising edges of recording pulses α1T and α1′T; a reference time Tsync corresponding to a clock mark formed at a predetermined position on a recording track is generated; a modulation signal corresponding to each mark length and space is generated by taking the reference time Tsync a start point; four reference clocks are generated, the four reference clocks being a reference clock 1a with a period of 2T which is generated with the delay time Td1 from the reference time Tsync taken as a start point, a reference clock 2a with a period of 2T which leads the reference clock 1a by 0.5T, a reference clock 1b with a period of 2T which leads the reference clock 1a by 1T, and a reference clock 2b with a period of 2T which leads the reference clock 1a by 1.5T; when recording a mark of nT=2LT, gate groups G1a and G1b corresponding to timings of α1T, αiT (2≦i≦m−1) and αmT sections are generated in synchronism with either the reference clock 1a or 1b; when recording a mark of nT=(2L+1)T, gate groups G2a and G2b corresponding to timings of α1′T, αi′T (2≦i≦m−1) and αm′T sections are generated in synchronism with either the reference clock 2a or 2b; when n is even, a gate G3 of Σ(αi+βi)T is generated with the delay time Td1 from the front end of the nT mark taken as a reference; when n is odd, a gate G4 of Σ(αi′+βi′)T is generated with the delay time T′d1 from the front end of the nT mark taken as a reference; a time that elapses from the reference time Tsync as a start point to the front end of the nT mark is counted as the number of reference clocks T; when the elapsed time is an even number times the reference clock T, the gate signal group G1a or G2b is selected according to whether n is even or odd; when the elapsed time is an odd number times the reference clock T, the gate signal group G1b or G2a is selected according to whether n is even or odd; when both G3 and G4 are off, recording light with an erase power Pe is radiated; when either G3 or G4 is on, recording light with a bias power Pb is radiated; when G3 and G1a are on at the same time, recording light with a recording power Pw is radiated in response to a G1a-on section; when G3 and G1b are on at the same time, recording light with a recording power Pw is radiated in response to a G1b-on section; when G4 and G2a are on at the same time, recording light with a recording power Pw is radiated in response to a G2a-on section; and when G4 and G2b are on at the same time, recording light with a recording power Pw is radiated in response to a G2b-on section.
- 21. An optical recording method according to claim 11, wherein when performing a mark length modulation scheme recording on the same recording medium by using a plurality of linear velocities v while keeping v×T constant,for L equal to or greater than 2, the periods of (αi+βi)T and (αi′+βi′)T in 2≦i≦m−1 are kept constant independently of the linear velocity, Pwi, Pbi and Pe in each i are kept almost constant independently of the linear velocity, and αi and αi′ (2≦i≦m) are decreased as the linear velocity lowers.
- 22. An optical recording method according to claim 21, wherein αiT and αi′T (2≦i≦m−1) are kept almost constant independently of the linear velocity.
- 23. An optical recording method according to claim 10, whereinwhen the mark length is expressed as nT=2LT (L is an integer equal to or larger than 2), the mark is divided into a division number m=L of sections and αi and βi in recording pulse sections αiT and off pulse sections βiT (these can change according to a value of L) are defined as follows: Td1+α1=2+ε1 βi−1+αi=2 (2≦i≦m) when the mark length is expressed as nT=(2L+1)T, the mark is divided into a division number m=L of sections and αi′ and βi′ in recording pulse sections α1′T and off pulse sections βi′T (these can change according to a value of L) are defined as follows: Td1′+α1′=2+ε1′β1′+α2′=2.5+ε2′βi−1′+α1′=2 (3≦i≦m−1) βm−1′+αm′=2.5+ε3′(where when L=2, β1′+α2′=2.5+ε2′ or β1′+α2′=3+ε2′; Td1 and Td1′ are almost constant real numbers between −2 and 2, not dependent on L; and ε1, ε1′, ε2′ and ε3′ are real numbers between −1 and 1); and β1, α2, βm−1, αm, β1′, α2′, βm−1′ and αm′ satisfy the following equation β1+α2+βm−1+αm+Δ2=β1′+α2′+αm−1′+αm′(where Δ2=0.8 to 1.2).
- 24. An optical recording method according to claim 23, wherein for L equal to or more than 3, β1′=β1+approximately 0.5, βm−1′=βm−1+approximately 0.5, α1=0.8 α1′ to 1.2 α1′, αm=0.8 αm′ to 1.2 αm′ and βm=0.8 βm′ to 1.2 βm′.
- 25. An optical recording method according to claim 23, wherein for all L, a delay time Td1 or Td1′ with respect to a front end of a mark length to be recorded is provided at rising edges of recording pulses α1T and α1′T;a reference time Tsync corresponding to a clock mark formed at a predetermined position on a recording track is generated; a modulation signal corresponding to each mark length and space is generated by taking the reference time Tsync as a start point; four reference clocks are generated, the four reference clocks being a reference clock la with a period of 2T which is generated from the reference time Tsync taken as a start point, a reference clock 2a with a period of 2T which leads the reference clock 1a by 0.5T, a reference clock 1b with a period of 2T which leads the reference clock 1a by 1T, and a reference clock 2b with a period of 2T which leads the reference clock 1a by 1.5T; when recording a mark of nT=2LT, gate groups G1a and G1b corresponding to timings of α1T, αiT (2≦i≦m−1) and αmT sections are generated in synchronism with either the reference clock 1a or 1b; when recording a mark of nT=(2L+)T, gate groups G2a and G2b corresponding to timings of α1′T, αi′T (2≦i≦m−1) and αm′T sections are generated in synchronism with either the reference clock 2a or 2b; when n is even, a gate G3 of Σ(αi+βi)T is generated with the delay time Td1 from the front end of the nT mark taken as a reference; when n is odd, a gate G4 of Σ(αi′+βi′)T is generated with the delay time Td1 from the front end of the nT mark taken as a reference; a time that elapses from the reference time Tsync as a start point to the front end of the nT mark is counted as the number of reference clocks T; when the elapsed time is an even number times the reference clock T, the gate signal group G1a or G2b is selected according to whether n is even or odd; when the elapsed time is an odd number times the reference clock T, the gate signal group G1b or G2a is selected according to whether n is even or odd; When both G3 and G4 are off, recording light with an erase power Pe is radiated; when either G3 or G4 is on, recording light with a bias power Pb is radiated; when G3 and G1a are on at the same time, recording light with a recording power Pw is radiated in response to a G1a-on section; when G3 and G1b are on at the same time, recording light with a recording power Pw is radiated in response to a G1b-on section; when G4 and G2a are on at the same time, recording light with a recording power Pw is radiated in response to a G2a-on section; and when G4 and G2b are on at the same time, recording light with a recording power Pw is radiated in response to a G2b-on section.
- 26. An optical recording method according to claim 23, wherein when performing a mark length modulation scheme recording on the same recording medium by using a plurality of linear velocities v while keeping v×T constant,for L equal to or greater than 2, the periods of (βi−1+αi)T and (βi−1′+αi′)T in 2≦i≦m are kept constant independently of the linear velocity, Pwi, Pbi and Pe in each i are kept almost constant independently of the linear velocity, and αi and αi′(2≦i≦m) are decreased as the linear velocity lowers.
- 27. An optical recording method according to claim 10, wherein said at least two recording marks with different n's have each time length of the recording mark such that said each time length is adjacent to another.
- 28. An optical recording method according to claim 27, where at least one of (α1+β1)T and (αm+βm)T is different from any one of the at least two recording marks with different n's.
- 29. An optical recording method according to claim 27, where at least one of (β1+α2)T and (βm−1+αm)T is different from any one of the at least two recording marks with different n's.
- 30. An optical recording method according to claim 10, wherein αi+βi (2≦i≦m−1) or βi−1+αi (2≦i≦m−1) takes a value of 2 independently of a real number i.
- 31. An optical recording method according to claim 1, wherein the erase power Pe of Pbi≦Pe≦Pwi (1≦i≦m) is radiated in a time length of the spaces.
- 32. An optical recording method according to claim 1, wherein the recording medium is a phase change type optical recording medium in which a crystal state is taken as an unrecorded/erased state and an amorphous state is taken as a recorded mark.
- 33. An optical recording method according to claim 1, wherein for the time length of all the recording marks, 4≧n/m≧1.5, Σi(αi)≦0.6 n and Pbi/Pe≦0.2 are satisfied.
- 34. An optical recording method according to claim 1, wherein the linear velocity during recording is 10 m/s or higher and a minimum mark length is less than 0.8 μm.
- 35. An optical recording method according to claim 1, wherein a wavelength of the recording light is less than 500 nm, a numerical aperture of a lens for focusing the recording light is 0.6 or more, and the minimum mark length is less than 0.3 μm.
- 36. An optical recording method according to claim 1, wherein the mark length modulation scheme is an 8-16 modulation scheme or a (1, 7)-RLL-NRZI modulation scheme.
- 37. An optical recording method according to claim 1, wherein the mark length modulation scheme is an EFM modulation scheme in which the recording is performed by setting the linear velocity during recording to 10 or more times a CD reference linear velocity of 1.2 m/s to 1.4 m/s and keeping the recording linear density constant.
- 38. An optical recording method according to claim 1, wherein the mark length modulation scheme is an EFM modulation scheme in which the recording is performed by setting the linear velocity during recording to two or more times a DVD reference linear velocity of 3.49 m/s and keeping the recording linear density constant.
- 39. A phase change type optical recording medium recorded by the optical recording method claimed in claim 1, the phase change type optical recording medium having a recording layer made of MzGey(SbxTe1−x)1−y−z alloy (where 0≦z≦0.1, 0≦y≦0.3, 0.8≦x; and M is at least one of In, Ga, Si, Sn, Pb, Pd, Pt, Zn, Au, Ag, Zr, Hf, V, Nb, Ta, Cr, Co, Mo, Mn, Bi, O, N and S).
Priority Claims (2)
Number |
Date |
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Kind |
11-138067 |
May 1999 |
JP |
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2000-076514 |
Mar 2000 |
JP |
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Parent Case Info
(This is a continuation application of International patent application No.PCT/JP00/03036, filed May 11, 2000)
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Continuations (1)
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PCT/JP00/03036 |
May 2000 |
US |
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09/884121 |
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