Source: http://www.google.com/patents/US7682678?dq=5,490,216
Timestamp: 2017-04-28 21:17:51
Document Index: 753071243

Matched Legal Cases: ['§ 119', 'Application No. 2003', 'Application No. 5', 'Application No. 5', 'Application No. 5', 'art 1']

Patent US7682678 - Optical information recording medium, recording and readout methods using ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsAn optical information recording medium includes a substrate formed in a concave-convex state by providing pits or grooves corresponding to recorded information, used for optically reproducing the information by irradiation of a light beam, and may also include a recording layer. The optical information...http://www.google.com/patents/US7682678?utm_source=gb-gplus-sharePatent US7682678 - Optical information recording medium, recording and readout methods using the same, optical information recording device, and optical information readout deviceAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS7682678 B2Publication typeGrantApplication numberUS 10/804,328Publication dateMar 23, 2010Filing dateMar 18, 2004Priority dateJun 6, 2003Fee statusPaidAlso published asCN1573990A, CN1573990B, DE602004020146D1, EP1484757A2, EP1484757A3, EP1484757A8, EP1484757B1, US20040247815Publication number10804328, 804328, US 7682678 B2, US 7682678B2, US-B2-7682678, US7682678 B2, US7682678B2InventorsNobuyuki Takamori, Hideharu Tajima, Go Mori, Masaki YamamotoOriginal AssigneeSharp Kabushiki KaishaExport CitationBiBTeX, EndNote, RefManPatent Citations (61), Non-Patent Citations (4), Referenced by (2), Classifications (15), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetOptical information recording medium, recording and readout methods using the same, optical information recording device, and optical information readout device
US 7682678 B2Abstract
An optical information recording medium includes a substrate formed in a concave-convex state by providing pits or grooves corresponding to recorded information, used for optically reproducing the information by irradiation of a light beam, and may also include a recording layer. The optical information recording medium includes a temperature responsive layer 21 whose reflectance and/or transmittance for the light beam changes with an increase in temperature caused by the irradiation of a light beam and a light absorption layer 22. With such an arrangement, the present invention provides an optical information recording medium enabling secure and highly accurate readout of information recorded with high density, a recording method and a readout method using the same, a readout device, and a recording device.
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2003/162871 filed in Japan on Jun. 6, 2003, the entire contents of which are hereby incorporated by reference.
The present invention relates to an optical information recording medium, recording and readout methods using the same; and further relates to an optical information recording device, and an optical information readout device. More specifically, the present invention relates to an optical information recording medium for optically reproducing or both recording and reproducing information with an optical beam (e.g. a laser beam), such as an optical disk, in which recording density is improved by having a layer for changing the optical characteristic depending on temperature; recording and readout methods using such an optical information recording medium; an optical information recording device; and an optical information readout device.
With the development of digitalization in the information-oriented society, there has been a demand for a writable medium which offers higher density recording and readout.
Further, Japanese Laid-Open Patent Application No. 5-12673/1993 has such description that “This temperature dependent light transmittance changeable medium is formed by, for example, a polymeric material or an organic material . . . , a material whose transmittance is increased in a high temperature area may be adopted for such a material, for example. Such a change in transmittance may be caused by using a material whose light transmittance is increased from dissolution of the material, or may be caused by changing regularity of molecular alignment of a liquid crystal material. Further, the material may be a phase change material or the like, and the light transmittance of such a material can be changed, for example, by heating and cooling a chalcogenide in an amorphous state to cause crystallization.” However, this description fails to describe a specific example of the material whose light transmittance is increased in a high temperature area. For this reason, the invention disclosed in Japanese Laid-Open Patent Application No. 5-12673/1993 cannot be realized by those in the art, based on common technologies at the time when Japanese Laid-Open Patent Application No. 5-12673/1993 is written or published.
The present invention is made in view of the foregoing demand for performing recording and readout with high density, and an object of the invention is to provide an optical information recording device capable of secure readout of information with high accuracy even when the information is recorded with high density; a recording method and a readout method using the medium; a readout device; and recording device.
One Embodiment of an optical information recording medium according to the present invention will be described below with reference to the drawings.
The transparent resin layer 11 is transparent for the wavelength of the readout beam 30, so as to allow incident of the readout beam 30. With this arrangement, the optical information recording medium 1 a receives incident light of the readout beam 30 from the transparent resin layer 11. The present invention does not particularly specify the material for constituting the transparent resin layer 11. For example, the material of the transparent resin layer 11 may be a thermoplastic transparent resin (plastic) such as a polycarbonate, an amorphous polyolefin, a thermoplastic polyimide, a PET (Polyethylene Terephthalate), a PEN (Polyether Nitrile), or a PES (Polyether Sulfone); a thermosetting transparent resin such as a thermosetting polyimide or an ultraviolet-curing acrylic resin; or a composition of any of these materials. Though its general desirable range of thickness is approximately 1 μm–100 μm, the transparent resin layer 11 may have a thickness around 0.1 mm–1.2 mm for offering appropriate strength of the optical information recording medium 1 a. Note that, the transparent resin layer 11 may instead be a layer made of other kinds of transparent material, for example, a glass or a composition of a glass and a transparent resin. The appropriate thickness of such a layer is approximately 0.1 mm–1.2 mm.
The material for constituting the substrate 12 is required to offer an appropriate strength of the optical information recording medium 1 a. The optical characteristic of the material of the substrate 12 is however not particularly limited, and therefore the material does not have to be transparent. The material of the substrate 12 may be a glass; a thermoplastic transparent resin such as a polycarbonate, an amorphous polyolefin, a thermoplastic polyimide, a PET, a PEN, or a PES; a thermosetting transparent resin such as a thermosetting polyimide or an ultraviolet-curing acrylic resin; a metal; or a composition of any of these materials. The thickness of the substrate 12 is preferably 0.3 mm–1.2 mm, however not particularly limited. Further, an appropriate pitch for the pits is approximately 0.3 μm–1.6 μm and an appropriate depth of the pitch is approximately 30 nm–200 nm. Further, for the guiding grooves, an appropriate range is approximately 0.3 μm–1.6 μm for the pitch, and approximately 30 nm–200 nm for the depth.
The temperature responsive layer 21 has such a function that the light transmittance with respect to the wavelength of the readout beam 30 changes with a rise in temperature of the light absorption layer 22 due to irradiation of the readout beam 30. The temperature responsive layer 21 contains a translucent material whose transmittance reversibly changes as the temperature changes; more specifically, the transmittance with respect to the wavelength of the readout light beam changes as the temperature increases. As an example of the material for constituting the temperature responsive layer 21, preferably adopted is a material causing a change of the transmittance of the temperature responsive layer 21 with a rise in temperature in a certain wavelength range; to be more specific, when the temperature rises from 20° C. to 18° C., the light transmittance of the temperature responsive layer 21 changes in a range of ±80%. One example of such a material may be a thermochromic material whose transmittance is changed when the chemical structure is changed upon heat absorption. A specific example of the thermochromic material whose transmittance decreases with a change of the temperature may be an inorganic thermochromic material such as a metal oxide, or an organic thermochromic material such as a lactone, a fluorane, or the like which is mixed with an alkali; or a leuco dye material or the like mixed with an organic acid. The most preferable material among these is a metal oxide, which changes the width of its forbidden band with a change of temperature, and changes the transmittance of wavelengths of its absorption edge. With this characteristic, the metal oxide is not likely to change its composition or structure even when it causes a chemical change of structure due to a change of temperature, and therefore it is superior in durability. For example, ZnO (Zinc Oxide) in particular, SnO2, CeO2, NiO2, In2O3, TiO2, Ta2O5, VO2, SrTiO3, or the like can be used as the metal oxide material. The thickness of temperature responsive layer 21, which depends on the material, is preferably not less than 100 nm, and more appropriately in a range of 500 nm–800 nm. Accordingly, the preferred material of the temperature responsive layer 21 is a ZnO (Zinc Oxide) film with a thickness of equal to or greater than 100 nm.
The light absorption layer 22 facilitates a change in temperature of the temperature responsive layer 21 from irradiation of the readout beam 30. More specifically, the light absorption layer 22 has a function of changing the quantity of light absorbed in the temperature responsive layer 21 (reflectance and/or transmittance of the temperature responsive layer 21). The light absorption layer 22 is preferably made of material which absorbs a readout laser beam (readout beam 30) to exchange it into heat. Specifically, examples of the material for the light absorption layer 22 include: Si film; Ge film; phase change film such as AgInSbTe film or GeSbTe film; magnetooptical film such as TbFeCo film, DyFeco film, or GdFeCo film; and alloy film of the aforementioned materials. Especially, the material for the light absorption layer 22 is most preferably Si film. The thickness of the light absorption layer 22, which depends on the material, can be adjusted and is preferably not less than 10 nm, and more appropriately in a range of 5 nm–300 nm. Accordingly, the preferred material of the light absorption layer 22 is a Si (Silicon) film with a thickness of equal to or greater than 10 nm.
Note that, the material of the heat insulation layer 24 is not particularly limited provided that it has low thermal conductivity. Note that, in the case of an optical information recording medium including the reflection layer 23, the heat insulation layer 24 is preferably transparent. In the case of an optical information recording medium not including the reflection layer 23, the heat insulation layer 24 is preferably made of material having high reflectance. Examples of the material of the heat insulation layer 24 include SiN film and AlN film, and the preferred material of the heat insulation layer 24 is SiN film. The thickness of the heat insulation layer 24, which is not particularly limited, can be adjusted so as to be a thickness which realizes a desired transmittance or reflectance. For example, the thickness of the heat insulation layer 24 can be approximately 20 nm–100 nm.
Here, the irradiation of the readout beam 30 with respect to the optical information recording medium 1 a is carried out by providing a high temperature section and a low temperature section in the light beam spot of the temperature responsive layer 21. For example, when the readout beam 30 is incident on the side having the transparent resin layer 11 and scans the front surface of the readout-only optical information recording medium 1 a in a predetermined direction, there arises temperature gradient in a readout beam spot 33 of the front surface of the temperature responsive layer 21 in a traveling direction of the readout beam spot 33, as shown in FIG. 13. As a result, the readout beam spot 33 of the front surface of the temperature responsive layer 21 has a high temperature section 33 a and a low temperature section 33 b. The temperature in the high temperature section 33 a is equal to or greater than 60° C. and less than 180° C., and the temperature of the low temperature section 33 b is equal to or greater than 20° C. and less than 60° C.
Further, in addition to this, the optical information recording media 1 c through 1 f including the heat insulation layer 24, as shown respectively in FIGS. 22 through 25, heat generated in the light absorption layer 22 transfers to the temperature responsive layer 21 more efficiently, so that light is further blocked by the high temperature section 33 a. To be more specific, the temperature responsive reflection layer 13 is turned to low reflectance state with the temperature equal to or greater than 60° C. and less than 180° C., and is turned to high reflectance state with the temperature equal to or greater than 20° C. and less than 60° C., for example. Further, the temperature responsive reflection layer 13 is more efficiently turned to low reflectance state by having the light absorption layer 22 and the heat insulation layer 24.
Further, in the temperature responsive layer 21, the change of the temperature of the transmittance characteristic is preferably controlled by using optical interference effect due to light interference between the reflection light on one surface and the reflection light on the other surface. For the spectral reflectance characteristic of the temperature responsive layer 21, it is preferable that the minimum value caused by the optical interference effect between the reflection light on one surface and the reflection light on the other surface exists in the vicinity (preferably within ±20 nm, further preferable within ±10 nm) of the wavelength of the light beam. When the temperature responsive layer 21 has a large thickness of equal to or greater than 200 nm, there causes the optical interference effect between the reflection light on one surface and the reflection light on the other surface. For example, a film not including the light absorption layer 22, made up of a zinc oxide film (400 nm; temperature responsive layer 21) and an aluminum film (reflection layer 23), as shown in FIG. 17, has a minimum value (400 nm in FIG. 17) of the spectral reflectance characteristic of the temperature responsive reflection layer 13, resulting from the optical interference effect. With this effect, inclination of the reflectance in the vicinity of the absorption edge becomes steeper, and the degree of modulation (change of spectral transmittance in the wavelength of the readout beam 30 between the high temperature section 33 a and the low temperature section 33 b) can be increased. This makes it more difficult to transmit the readout beam 30 through the high temperature section 33 a, thus surely realizing high readout signal strength. Note that, the aluminum film having a thickness less than 40 nm does not cause such an optical interference effect, and therefore the spectral reflectance characteristic of the aluminum film has no minimum values, as shown in FIG. 16, for example.
Note that, FIG. 15 shows the spectral reflectance characteristics in the vicinity of the absorption edge of the temperature responsive layer 21 made of a ZnO film having the thickness of 400 nm, under a circumstance of a low temperature (30° C.) and under a circumstance of a high temperature (200° C.). FIG. 16 shows the spectral reflectance characteristics in the vicinity of the absorption edge of the temperature responsive reflection layer 13 made of a ZnO film having the thickness of 100 nm and a Al film having the thickness of 50 nm, under a circumstance of a low temperature (30° C.) and under a circumstance of a high temperature (200° C.). FIG. 17 shows the spectral reflectance characteristics in the vicinity of the absorption edge of the temperature responsive reflection layer 13 made of a ZnO film having the thickness of 400 nm and a Al film having the thickness of 50 nm, under a circumstance of a low temperature (30° C.) and under a circumstance of a high temperature (200° C.). FIG. 18 shows the spectral reflectance characteristics in the vicinity of the absorption edge of the temperature responsive reflection layer 13 made of a ZnO film having the thickness of 210 nm, a Si film having the thickness of 50 nm, and a Al film having the thickness of 30 nm, under a circumstance of a low temperature (30° C.) and under a circumstance of a high temperature (200° C.). FIG. 19 shows the spectral reflectance characteristics in the vicinity of the absorption edge of the temperature responsive reflection layer 13 made of a ZnO film having the thickness of 230 nm, a Si film having the thickness of 50 nm, and a Al film having the thickness of 30 nm, under a circumstance of a low temperature (30° C.) and under a circumstance of a high temperature (200° C.).
Another Embodiment of the present invention will be described below with reference to FIGS. 5 through 12 and FIGS. 27 through 34. For ease of explanation, materials having the equivalent functions as those shown in the drawings pertaining to Embodiment 1 above will be given the same reference symbols, and explanation thereof will be omitted here.
The recording layer 14 may be made of a material for recording typically used in the relevant field. For example, an organic dye material such as a cyanine or a phthalocyanine may be used for recordable optical information recording media 2 a through 2 l. Further, in case of rewritable (recording, readout and deletion type) optical information recording media 2 a through 2 l, a magnetooptical recording material such as a TbFeCo, or a phase change recording material such as an AgInSbTe, a GeTeSb, or an AgInSb can be used. When the optical information recording media 2 a through 2 l are constituted of a magnetooptical recording material such as a TbFeCo, the recording layer 14 preferably has a lamination structure made of a dielectric layer made of a dielectric material such as a SiN (Silicon Nitride), a recording layer made of an magnetooptical material, and a protection layer made of a protection material such as a SiN. Further, when the optical information recording media 2 a through 2 l are constituted of a phase change recording material such as an AgInSbTe, GeTeSb, or an AgInSb, the recording layer 14 preferably has a lamination structure made of a dielectric layer made of a ZnS—SiO2 film, a recording layer made of a phase change material such as an AgInSbTe, GeTeSb, or an AgInSb, and a protection layer made of a ZnS—SiO2 film. The thickness of the recording layer 14 is not limited but a range of 5 nm–500 nm is appropriate.
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No. 10/862,187, filed Jun. 4, 2004, Go Mori, et al.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS9159923Dec 18, 2008Oct 13, 2015Semiconductor Energy Laboratory Co., Ltd.Evaporation donor substrate, method for manufacturing the same, and method for manufacturing light-emitting deviceUS20100018639 *Oct 6, 2009Jan 28, 2010Sharp Kabushiki KaishaMethod of forming micropattern, method of manufacturing optical recording medium master copy, optical recording medium master copy, optical recording medium stamper, and optical recording medium* Cited by examinerClassifications U.S. Classification428/64.1, 430/270.11, 428/64.4International ClassificationG11B11/105, B32B3/02, G11B7/243, G11B7/005, G11B7/257, G11B7/0045, G11B7/24Cooperative ClassificationY10T428/21, G11B7/243, G11B7/257European ClassificationG11B7/257, G11B7/243Legal EventsDateCodeEventDescriptionMar 18, 2004ASAssignmentOwner name: SHARP KABUSHIKI KAISHA,JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TAKAMORI, NOBUYUKI;TAJIMA, HIDEHARU;MORI, GO;AND OTHERS;SIGNING DATES FROM 20040210 TO 20040212;REEL/FRAME:015122/0144Aug 28, 2013FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services