# US 7,609,603 B2 · Rewritable optical recording medium and optical recording method

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- Number: US 7,609,603 B2
- Document ID: US7609603B2
- Status: Granted
- Kind: B2
- Application number: 11/684,942
- Filed: 2007-03-12
- Published: 2007-07-12
- Granted: 2009-10-27
- Earliest claimed: 2002-02-13
- Assignees: Mitsubishi Kagaku Media Co., Ltd.
- Inventors: Takashi Ohno; Masae Kubo; Michikazu Horie; Masaaki Mizuno; Hiroyuki Hoshino; Akio Okamuro
- Web page: https://patentgrep.com/patent/US7609603B2

## CPC

- G11B 7/243: comprising inorganic materials only, e.g. ablative layers
- G11B 7/0045: Recording (G11B7/006, G11B7/0065 take precedence)
- G11B 7/00454: {involving phase-change effects}
- G11B 7/0062: {Overwriting strategies, e.g. recording pulse sequences with erasing level used for phase-change media}
- G11B 7/126: Circuits, methods or arrangements for laser control or stabilisation
- 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)
- G11B 7/259: based on silver
- G11B 7/26: Apparatus or processes specially adapted for the manufacture of record carriers
- G11B 2007/24312: {group 14 elements (e.g. Si, Ge, Sn)}
- G11B 2007/24314: {group 15 elements (e.g. Sb, Bi)}
- G11B 2007/24316: {group 16 elements (i.e. chalcogenides, Se, Te)}
- Y10T 428/21: Circular sheet or circular blank
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A rewritable optical recording medium includes a substrate and a phase-change type recording layer. A portion in a crystalline state corresponds to an unrecorded or erased state, and a portion in an amorphous state correspond to a recorded state, to record EFM modulated information by forming amorphous marks by irradiating the recording layer with a recording laser beam, and the recording is carried out by irradiating a recording laser beam having a wavelength of about 780 nm through an optical system having a numerical aperture NA of 0.5 or 0.55, at 24-times velocity or 32-times velocity of the reference velocity.

## Claims

### Claim 1

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.

### Claim 2 (depends on 1)

The recording method according to claim 1, wherein when m is at least 3, with the same division number m, βm−1′+αm′+βm′ in the case where n is an odd number, is larger by from 0.5 to 1.5 than βm−1+αm+βm in the case where n is an even number.

### Claim 3 (depends on 1)

The recording method according to claim 1, wherein when m is at least 3, the relations of Td1′=Td1, α1′=α1, β1+α2=1.5 to 2.5, βm−1+αm=1.5 to 2.5, βm−1′=βm−1+Δm−1 (where Δm−1=0 to 1), αm′=αm+Δm (where 0<Δm≦1), βm′=βm+Δm′ (where Δm′=0 to 1) and Δm−1+Δm+Δm′=0.5 to 1.5 are satisfied, and further, Td1, α1, β1, αc, βm−1, Δm−1, αm, βm and Δm′ are constant irrespective of m, and Δm takes either value of Δm1 or Δm2 depending upon m.

### Claim 4 (depends on 1)

The recording method according to claim 1, wherein when m is at least 3, Δm=Δm1=Δm2.

### Claim 5 (depends on 1)

The recording method according to claim 1, wherein when m is at least 3, at least one formula is satisfied among Td1+α1=2, α1=αc, β1+α2=2, βm−1+αm=2 and αm=αc.

### Claim 6 (depends on 3)

The recording method according to claim 3, wherein when m is at least 3, with the same division number m, the relations of Td1′=Td1, α1=α1′, Td1+α1=2, βm−1′=βm−1+Δm−1 (where Δm−1=0 to 1), αm′=αc+Δm (where 0<Δm≦1), Δm−1+Δm+Δm′=0.5 to 1.5, βm′=βm+Δm′ and Δm′=0 to 1, are satisfied, and α1, αc, Δm−1, Δm, βm and Δm′ are constant irrespective of m,
when m=2, α1, α1′, β1, β1′, α2, α2′, β2 and β2′ are made to be equal to α1, α1′, β2 (=βC), β2′(=βc+Δm−1), α3(=αc), α3′(=αc+Δm), β3 and β3′(=β3+Δm′) in the case where m is at least 3, respectively.

### Claim 7 (depends on 1)

The recording method according to claim 1, wherein α1′ where n=3, is larger than α1′ where n is at least 4.

### Claim 8 (depends on 1)

The recording method according to claim 1, wherein when Td1′ where n=3 and 5 is represented by Td1a and Td1c, respectively, Td1 where n=4 is represented by Td1b, and Td1 and Td1′ where n is at least 6 are represented by Td1d, at least one selected from Td1a, Td1b and Td1c takes a value different from Td1d.

### Claim 9 (depends on 1)

The recording method according to claim 1, 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 Vmax 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 αi=αimax (where i=1 to m) at the Vmax is from 0.5 to 2, and αi′=αimax′ (where i=1 to m) at the Vmax is from 0.5 to 2, and αi and αi′ (where i=1 to m) are permitted to simply decrease as the linear velocity lowers.

### Claim 10 (depends on 9)

The recording method according to claim 9, wherein when the minimum linear velocity Vmin 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, Td1+α1, Td1′+α1′, βi−1+αi=2, and βi−1′+αi′=2 (where i=3 to m−1) are, respectively, constant irrespective of the linear velocity within a linear velocity range of from the Vmin to the Vmax when m is at least 3.

### Claim 11 (depends on 9)

The recording method according to claim 9, wherein at any linear velocity to be used, βm=0 to 2, and βm′=0 to 3, and βm and βm′ are permitted to simply increase as the linear velocity lowers.

### Claim 12 (depends on 9)

The recording method according to claim 9, wherein Δm′ is permitted to simply increase as the linear velocity lowers.

### Claim 13 (depends on 9)

The recording method according to claim 9, wherein among Td1′, α1′ and β1′ where n=3, Td1′ and β1′ are permitted to simply increase as the linear velocity lowers, and α1′ is permitted to simply decrease as the linear velocity lowers.

### Claim 14 (depends on 9)

The recording method according to claim 9, wherein at any linear velocity to be used, βiT (where i=1 to m) and βi′T (where i=1 to m−1) are at least 2 nsec.

### Claim 15 (depends on 9)

The recording method according to claim 9, wherein when 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.

### Claim 16 (depends on 15)

The recording method according to claim 15, 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.

### Claim 17 (depends on 15)

The recording method according to claim 15, wherein the record area is divided into a plurality of imaginary zones in every certain radius, and βm=0 to 3, and further, βm is made to simply increase towards the inner peripheral zone, and αi and αi′ are made to simply decrease towards the inner peripheral zone.

### Claim 18 (depends on 15)

The recording method according to claim 15, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.

### Claim 19 (depends on 9)

The recording method according to claim 9, wherein when 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.

### Claim 20 (depends on 19)

The recording method according to claim 19, 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.

### Claim 21 (depends on 19)

The recording method according to claim 19, wherein the record region is divided into a plurality of imaginary zones in every certain radius, and βm=0 to 3, and further, βm is made to simply increase towards the inner peripheral zone, and αi and αi′ are made to simply decrease towards the inner peripheral zone.

### Claim 22 (depends on 19)

The recording method according to claim 19, wherein the values of Pb, Pw and Pe/Pw are substantially constant at any radial position.