Write-once-read-many optical disk having low-to-high recording property accommodating short wavelength recording

• US 8,846,298 B2
• Filed: 11/08/2010
• Issued: 09/30/2014
• Est. Priority Date: 07/28/2005
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Sasa, Noboru
• Primary Examiner(s): ANGEBRANNDT, MARTIN J
• Application Number:
  US12/941,451
• Publication Number:
  US 20110116353A1
• Time in Patent Office: 1,422 Days
• Field of Search: None
• US Class Current: 430/270.18
• CPC Class Codes: G11B 2007/24705 Cyanine
• CPC Class Codes: G11B 2007/25706 containing transition metal elements (Zn, Fe, Co, Ni, Pt)
• CPC Class Codes: G11B 2007/2571 containing group 14 elements except carbon (Si, Ge, Sn, Pb)
• CPC Class Codes: G11B 2007/25715 containing oxygen
• CPC Class Codes: G11B 2007/25716 containing sulfur
• CPC Class Codes: G11B 7/00455 involving reflectivity, absorption or colour changes
• CPC Class Codes: G11B 7/00456 Recording strategies, e.g. pulse sequences G11B7/0062 takes precedence
• 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 7/24035 Recording layers substrates also used as recording layers G11B7/24047
• CPC Class Codes: G11B 7/258 of reflective layers

Abstract

A write-only-read-many type optical recording medium includes a substrate, an organic material layer having a light absorption function that is sufficient for recording in the recording/reproduction wavelength range, the organic material layer being situated on the substrate, and a reflection layer being situated on the organic material layer. The recording medium is configured to have a Low-to-High recording property and record with a laser having a wavelength that is no greater than 500 nm.

Claims

1. A recording/reproduction method exhibiting a Low-to-High recording property, the method comprising a step of:

performing a recording/reproduction process on an optical recording medium by using a laser having a wavelength that is no greater than 500 nm;

wherein the optical recording medium includes a substrate, wherein the substrate has grooves with a groove depth of 55 nm,

an organic material layer provided on the substrate and having a thickness of 50 nm to 300 nm, the organic material layer having a light absorption function that is sufficient for recording in a recording/reproduction wavelength range,

a reflection layer provided on the organic material layer and having a thickness of from 50 nm to 300 nm, a heat insulating layer provided adjacent to the organic material layer and having a thickness of from 5 nm to 200 nm, and

a cover layer;

wherein an unrecorded part of the optical recording medium is configured to exhibit a reflectivity that is lower than a reflectivity of a recorded part of the optical recording medium and wherein the recording/reproduction characteristics are obtained in a blue laser wavelength range;

wherein the light absorption function of the organic material layer is provided solely by a material consisting of a single organic material having a first absorption band situated toward a long wavelength side with respect to the recording/reproduction wavelength range,

a second absorption band that does not belong to the first absorption band, the second absorption band situated in the vicinity of the recording/reproduction wavelength range, and

a third absorption band situated toward a short wavelength side with respect to the recording/reproduction wavelength range, the third absorption band exhibiting an absorption greater than an absorption of the first absorption band, wherein the third absorption band has a largest absorption wavelength that is no greater than 300 nm,

wherein the optical recording medium provides low-to-high recording at a recording power range of from 2 mW to 11 mW at a linear recording speed of 6 m/sec.

2. The recording/reproduction method as claimed in claim 1, wherein the heat insulating layer includes any of SiO₂, ZnS.SiO₂, and ZrO₂ as a main component.

3. The recording/reproduction method as claimed in claim 1, wherein the heat insulating layer includes ZnS, ZrO₂, Y₂O₃, and SiO₂.

4. The recording/reproduction method as claimed in claim 1, wherein the heat insulating layer includes ZrO₂, TiO₂, SiO₂, and X, wherein X includes at least one of Al₂O₃, MgO, CaO, NbO, Y₂O₃, and CeO.

5. The recording/reproduction method as claimed in claim 1, wherein the substrate includes groove parts and land parts, wherein recording areas are formed in both the groove parts and the land parts.

6. The recording/reproduction method as claimed in claim 1, wherein the heat insulating layer comprises a member selected from nitride non-oxides, carbide non-oxides, boride non-oxides, sulfide non-oxides, silicide non-oxides, and carbon non-oxides.

7. The recording/reproduction method as claimed in claim 1, wherein the reflectivity of the recorded part increases continuously as recording power is increased, over a recording power range of from 0.77×

Po to 1.13×

Po, wherein Po represents a recording power where jitter is minimized.

8. The recording/reproduction method as claimed in claim 1, wherein the reflectivity of the unrecorded part is no greater than 10%.

9. A recording/reproduction method exhibiting a Low-to-High recording property, the method comprising a step of:

performing a recording/reproduction process on an optical recording medium by using a laser having a wavelength that is no greater than 500 nm;

wherein the optical recording medium consists essentially of;

a substrate, a reflection layer, an organic material layer, a light absorption layer, and a cover layer;

wherein the organic material layer is situated on the substrate and has a thickness of 50 nm to 300 nm, the organic material layer having a light absorption function that is sufficient for recording in a recording/reproduction wavelength range of no more than 500 nm;

wherein the light absorption layer is situated adjacent to the organic material layer and has a thickness of 5 nm to 150 nm;

wherein the reflection layer is provided on the organic material layer and has a thickness of from 50 nm to 300 nm; and

wherein the organic material satisfies a relation of (light absorption function of organic material layer in recording/reproduction wavelength area) <

(light absorption function of light absorption layer in recording/reproduction wavelength area);

wherein an unrecorded part of the optical recording medium is configured to exhibit a reflectivity that is lower than a reflectivity of a recorded part of the optical recording medium;

wherein the light absorption function of the organic material layer is provided solely by a material consisting of a single organic material having;

a first absorption band situated toward a long wavelength side with respect to the recording/reproduction wavelength range,

a second absorption band that does not belong to the first absorption band, the second absorption band situated in the vicinity of the recording/reproduction wavelength range, and

a third absorption band situated toward a short wavelength side with respect to the recording/reproduction wavelength range, the third absorption band exhibiting an absorption greater than an absorption of the first absorption band, wherein the third absorption band has a largest absorption wavelength that is no greater than 300 nm,

wherein the optical recording medium provides low-to-high recording at a recording power range of from 2 mW to 11 mW at a linear recording speed of 6 m/sec.

10. The recording/reproduction method as claimed in claim 9, wherein the substrate includes groove parts and land parts, wherein recording areas are formed in both the groove parts and the land parts.

11. The recording/reproduction method as claimed in claim 9, wherein the reflectivity of the recorded part increases continuously as recording power is increased, over a recording power range of from 0.77×

Po to 1.13×

Po, wherein Po represents a recording power where jitter is minimized.

12. The recording/reproduction method as claimed in claim 9, wherein the reflectivity of the unrecorded part is no greater than 10%.