# US 7,611,762 B2 · Optical recording medium

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- Number: US 7,611,762 B2
- Document ID: US7611762B2
- Status: Granted
- Kind: B2
- Application number: 11/397,551
- Filed: 2006-04-05
- Published: 2006-08-17
- Granted: 2009-11-03
- Earliest claimed: 2002-09-13
- Assignees: Ricoh Company, Ltd.
- Inventors: Hiroshi Deguchi; Hajime Yuzurihara; Eiko Hibino; Hiroshi Miura; Mikiko Abe; Shinya Narumi; Takeshi Kibe; Katsuyuki Yamada; Satoshi Taniguchi
- Web page: https://patentgrep.com/patent/US7611762B2

## CPC

- G11B 7/0062: {Overwriting strategies, e.g. recording pulse sequences with erasing level used for phase-change media}
- 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 7/243: comprising inorganic materials only, e.g. ablative layers
- G11B 7/252: of layers other than recording layers
- G11B 7/257: of layers having properties involved in recording or reproduction, e.g. optical interference layers or sensitising layers or dielectric layers, which are protecting the recording layers
- G11B 7/259: based on silver
- G11B 7/2534: polycarbonates [PC]
- 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

An optical disc having a transition linear velocity of 8-11 m/s when irradiating continuous light with 11±1 mW and a wavelength of 660±10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfying the following condition: ΔR=|Rb−Ra|≦3% where Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording. In one recording mode therefor, the disc is rotated at a constant angular velocity so as to have a linear velocity of 3-4 m/s on an innermost track and a linear velocity of 8-9 m/s on an outermost track. In another mode, the disc is rotated at a constant angular velocity so as to have a linear velocity of 5-6 m/s on an innermost track and a linear velocity of 13-14 m/s on an outermost track.

## Claims

### Claim 1

An optical recording medium comprising:
a transparent substrate;
a lower protective layer disposed above the transparent substrate;
a recording layer containing a phase-change material, disposed above the lower protective layer;
an upper protective layer disposed above the recording layer; and
an interfacial layer disposed at least one of between the recording layer and the lower protective layer and between the recording layer and the upper protective layer; and
a sulfuration-inhibiting layer formed over said upper protective layer,
wherein the optical recording medium has a transition linear velocity ranging from 8 m/s to 11 m/s as determined by irradiating continuous light with a power of 11±1 mW and a wavelength of 660±10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfies the following condition:
ΔR=|Rb−Ra|≦3%
where ΔR is an absolute value of the difference between Ra and Rb; Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording, and
wherein the optical recording medium is recordable with at least two recording modes of a first recording mode and a second recording mode, in which the first recording mode is that the optical recording medium is rotated at a constant angular velocity so as to have a linear velocity of 3 m/s to 4 m/s when recording on an innermost track of the optical recording medium and to have a linear velocity of 8 m/s to 9 m/s when recording on an outermost track of the optical recording medium, and the second recording mode is that the optical recording medium is rotated at a constant angular velocity so as to have a linear velocity of 5 m/s to 6 m/s when recording on an innermost track of the optical recording medium and to have a linear velocity of 13 m/s to 14 m/s when recording on an outermost track of the optical recording medium.

### Claim 2 (depends on 1)

An optical recording medium according to claim 1, wherein the lower protective layer has a thickness of 40 nm to 220 nm.

### Claim 3 (depends on 1)

An optical recording medium according to claim 1, wherein the upper protective layer has a thickness of 2 nm to 20 nm.

### Claim 4 (depends on 1)

An optical recording medium according to claim 1,
wherein the phase-change material in the recording layer has an atomic ratio [Sb/(Sb+Te)] of Sb to the total of Sb and Te of 0.74 to 0.85,
wherein the phase-change material further contains at least one of Ag, In, and Ge,
wherein the atomic ratio of the total of Ag, In, and Ge to the total atoms in the phase-change material is 0.04 to 0.10, and
wherein the atomic ratios of Ag, In, and Ge to the total atoms in the phase-change material satisfy the following conditions:
0≦Ag≦0.01, 0.02≦In≦0.06, and 0.02≦Ge≦0.06.

### Claim 5 (depends on 1)

An optical recording medium according to claim 1,
wherein the phase-change material in the recording
layer has an atomic ratio [Sb/(Sb+Te)] of Sb to the total of Sb and Te of 0.74 to 0.79,
wherein the phase-change material further contains at least one of Ag, In, and Ge,
wherein the atomic ratio of the total of Ag, In, and Ge to the total atoms in the phase-change material is 0.04 to 0.10, and
wherein the atomic ratios of Ag, In, and Ge to the total atoms in the phase-change material satisfy the following conditions:
0≦Ag≦0.01, 0.02≦In≦0.06, and 0.02≦Ge≦0.06.

### Claim 6 (depends on 1)

An optical recording medium according to claim 1,
wherein the phase-change material in the recording layer further contains at least one of Ag, In, and Ge,
wherein the phase-change material has an atomic composition satisfying the following conditions;
0≦Ag≦0.015, 0.010≦In≦0.080, 0.600≦Sb≦0.800, 0.100≦Te≦0.300, and 0.010≦Ge≦0.080, wherein the atomic ratio of the total of Ag, In, and
Ge to the total atoms in the phase-change material is from 0.050 to 0.090, and wherein the atomic ratio [Ag/(Ag+In+Ge)] of Ag to the total of Ag, In, and Ge in the phase-change material is 0.10 or less.

### Claim 7 (depends on 1)

An optical recording medium according to claim 1, wherein the optical recording medium satisfies the following condition:
3.5<[Rmaxv−RCv]<5
where RCv is a recrystallization critical velocity (m/s) of the recording layer; and Rmaxv is a maximum recording linear velocity (m/s) of the recording layer.

### Claim 8 (depends on 1)

An optical recording medium according to claim 1, wherein the recording layer has a thickness of 2 nm to 22 nm.

### Claim 9 (depends on 1)

An optical recording medium according to claim 1, further comprising a reflective layer disposed above the sulfuration-inhibiting layer, wherein the reflective layer has a thickness of 90 nm to 200 nm.

### Claim 10 (depends on 1)

An optical recording medium according to claim 1, wherein the sulfuration-inhibiting layer contains 90 mol% or more of Si and SiC.

### Claim 11 (depends on 1)

An optical recording medium according to claim 1, wherein the interfacial layer contains at least one oxide selected from ZrO2, TiO2, SiO2, Al2O3, and Ta2O5.

### Claim 12 (depends on 1)

An optical recording medium according to claim 1, wherein the interfacial layer contains ZrO2, TiO2, and at least one selected from rare-earth metal oxides and oxides of Group IIa elements of the Periodic Table of Elements except Be and Ra.

### Claim 13 (depends on 12)

An optical recording medium according to claim 12, wherein the at least one selected from rare-earth metal oxides and oxides of Group IIa elements of the Periodic Table of Elements except Be and Ra is contained in an amount of 1 mol % to 10 mol % relative to ZrO2.

### Claim 14 (depends on 11)

An optical recording medium according to claim 11, wherein TiO2 is contained in the interfacial layer in an amount of 10 mol % to 50 mol % of the total oxides.

### Claim 15 (depends on 12)

An optical recording medium according to claim 12, wherein TiO2 is contained in the interfacial layer in an amount of 10 mol % to 50 mol % of the total oxides.

### Claim 16 (depends on 1)

An optical recording medium according to claim 1, wherein the interfacial layer has a thickness of 1 nm to 22 nm.

### Claim 17

An optical recording medium comprising:
a transparent substrate;
a lower protective layer disposed above the transparent substrate;
a recording layer containing a phase-change material, disposed above the lower protective layer;
an upper protective layer disposed above the recording layer;
an interfacial layer disposed at least one of between the recording layer and the lower protective layer and between the recording layer and the upper protective layer,
a sulfuration-inhibiting layer disposed above said upper protective layer;
wherein the optical recording medium has a transition linear velocity ranging from 8 m/s to 11 m/s as determined by irradiating continuous light with a power of 11±1 mW and a wavelength of 660±10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfies the following condition:
ΔR=|Rb−Ra|≦3%
where ΔR is an absolute value of the difference between Ra and Rb; Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording, and
wherein the optical recording medium is recordable with at least two recording modes of a first recording mode and a second recording mode, in which the first recording mode is that the optical recording medium is rotated at a constant angular velocity so as to have a linear velocity of 3 m/s to 4 m/s when recording on an innermost track of the optical recording medium and to have a linear velocity of 8 m/s to 9 m/s when recording on an outermost track of the optical recording medium, and the second recording mode is that the optical recording medium is rotated at a constant angular velocity so as to have a linear velocity of 5 m/s to 6 m/s when recording on an innermost track of the optical recording medium and to have a linear velocity of 13 m/s to 14 m/s when recording on an outermost track of the optical recording medium.