WO2001016947A1 - Disque optique, procede et appareil de lecture de donnees dudit disque - Google Patents
Disque optique, procede et appareil de lecture de donnees dudit disque Download PDFInfo
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- WO2001016947A1 WO2001016947A1 PCT/JP2000/005932 JP0005932W WO0116947A1 WO 2001016947 A1 WO2001016947 A1 WO 2001016947A1 JP 0005932 W JP0005932 W JP 0005932W WO 0116947 A1 WO0116947 A1 WO 0116947A1
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- light beam
- recording
- transparent substrate
- data
- recording film
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/2403—Layers; Shape, structure or physical properties thereof
- G11B7/24047—Substrates
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/005—Reproducing
- G11B7/0052—Reproducing involving reflectivity, absorption or colour changes
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/127—Lasers; Multiple laser arrays
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1374—Objective lenses
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
- G11B7/257—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers 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
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
- G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
- G11B2007/24302—Metals or metalloids
- G11B2007/24312—Metals or metalloids group 14 elements (e.g. Si, Ge, Sn)
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
- G11B2007/24302—Metals or metalloids
- G11B2007/24314—Metals or metalloids group 15 elements (e.g. Sb, Bi)
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/243—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials only, e.g. ablative layers
- G11B2007/24302—Metals or metalloids
- G11B2007/24316—Metals or metalloids group 16 elements (i.e. chalcogenides, Se, Te)
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
- G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
- G11B2220/2537—Optical discs
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
- G11B7/253—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates
- G11B7/2533—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins
- G11B7/2534—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of substrates comprising resins polycarbonates [PC]
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
- G11B7/258—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers
- G11B7/2585—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of reflective layers based on aluminium
Definitions
- the present invention relates to an optical disc, a reproducing method for reproducing data from the optical disc, and a reproducing apparatus thereof, and in particular, to an optical disc optimized for recording data at a higher density.
- the present invention relates to a method for reproducing data from an optical disc and a reproducing method for reproducing data from the optical disc.
- the present invention provides an optical disk in which two layers of a phase change type capable of recording, erasing, and reproducing are provided on one side thereof (hereinafter, simply referred to as a single-sided, two-layer phase change type optical disk).
- the present invention relates to a method and apparatus for reproducing the same, particularly, a phase-change layer capable of recording and erasing, which is reversibly changed in phase between amorphous and crystalline by irradiation with a light beam.
- a phase-change optical disc having two layers provided on one side thereof. The two layers are joined via an adhesive layer having a predetermined thickness, and a laser beam is focused on each layer from one side.
- optical disks have been attracting attention as large-capacity memories, and DVDs (Digit al Versatile Disks), which are high-density optical disks that enable video playback for about two hours, have actually become available. Practical dani.
- the recording density is higher than that of the current optical disc.
- optical disks with a large storage capacity and the development of various elemental technologies to achieve this is required. In order to achieve higher densities, for example, it is effective to reproduce smaller pits recorded on a disc using smaller convergence spots. It is known that there is.
- the size of the focusing spot is proportional to the wavelength of the laser beam of the light source, and inversely proportional to the numerical aperture (NA) of the objective lens.
- NA numerical aperture
- a compact disk which is an early optical disk product, uses a laser beam with a wavelength of 780 to 830 nm, but at present, it is a semiconductor laser.
- a laser that emits a laser beam having a wavelength of 685 to 635 nm, which belongs to the red region, has been put to practical use.
- semiconductor lasers belonging to the blue wavelength range of wavelengths from 400 to 42011111 has been advanced, and has almost reached the stage of practical use.
- technologies for increasing the number of apertures of the objective lens have been studied.
- optical discs include read-only discs such as CDs, write-once write-once discs such as CD-R, and read-only discs such as external memory of a computer.
- read-only discs such as CDs
- write-once write-once discs such as CD-R
- read-only discs such as external memory of a computer.
- rewritable discs There are three types of rewritable discs that can be recorded and erased. In addition, rewritable discs are used for playback, recording and erasing.
- phase-change optical disc a recording film whose phase is reversibly changed between an amorphous phase and a crystalline phase by being irradiated with a laser beam is used.
- the recording mark (amorphous state) and the back ground are irradiated by laser beam irradiation.
- the reflectance is different, and the data is reproduced by detecting the difference in the reflectance.
- Whether the laser-irradiated portion of the recording film becomes amorphous (mark) or crystalline (erased) depends on whether the temperature of the irradiated portion exceeds the melting point of the material composing the film. Or exceeding the crystallization temperature. Therefore, a laser beam whose intensity is modulated between a certain reference temperature between the melting point temperature and the crystallization temperature and a certain reference temperature equal to or higher than the crystallization temperature is generated, and the recording film is scanned with the laser beam.
- overwriting that is, recording can be executed simultaneously with erasure.
- LZG recording method In order to increase the recording density of such optical discs, the diameter of the condensed spot is reduced by shortening the laser wavelength, as described above. (LZG recording method) is used.
- data is recorded only on the recording film inside the groove (group) or only on the bank between the grooves, which is called the land.
- data is recorded in both ditches and embankments. That is, if the laser beam is scanning the groove, The groove depth is set so that the marks recorded on the bank are not optically visible, and when scanning the bank, the recorded marks written on the grooves are not optically visible.
- An optically defined method is used in which data is stably recorded on both sides.
- the wavelength of the semiconductor laser equipped with an optical head was set at 780 nm, and the NA (numeric) of the objective lens was set. (Rical aperture) is set at 0.45, and the thickness of CD discs is set at 1.2 mm.
- the semiconductor laser wavelength of the optical head is set at 65 nm
- the numerical aperture NA of the objective lens is set at 0.6
- the substrate of the DVD disk is set at 0.6.
- the thickness is set to 0.6 mm.
- the condensing spot diameter of the optical head is obtained when the wavelength of the laser is obtained and the numerical aperture of the lens is NA; It is proportional to LZNA. Therefore, in order to make the spot diameter smaller, it is customary to make the wavelength shorter and make the NA as large as possible. At this time, assuming that the thickness of the disk substrate is t, care should be taken to set a small coma aberration in proportion to t (NA) 3Z.
- the thickness of the substrate on the laser-incident side by increasing the wavelength of the semiconductor laser to a blue wavelength near 410 nm and NA as much as possible for the DVD as a boost DVD.
- Various proposals have been made.
- One example is the recording with a laser beam of 0.1 mm from the side of the 0.1 mm cover layer using an optical head with a wavelength of 410 nm and NA set to 085.
- the term “cover layer” means that if the substrate thickness is 0.1 mm, mechanical (physical) rigidity cannot be obtained.
- a high-density recording is achieved by applying or laminating a 0.1 mm cover layer on the surface of the substrate and irradiating the laser from the cover layer side instead of from the substrate side.
- FIG. 1 schematically shows the structure of a single-sided, two-layer RAM disk described in the above paper.
- a two-layer RAM disk on one side has a first RAM layer 132 provided on a polycarbonate (PC) substrate 131, and on another PC substrate 13
- a second RAM layer 134 is provided, and the structure is formed by bonding together a UV curable resin film 135 having a thickness of 40 ⁇ m.
- the 1 RAM layer 1 3 2, ZnS-Si0 2 protective film 1 3 2 A from the PC substrate side, GeSbTe recording layer 1 3 2 B and ZnS-Si0 2 coercive Mamorumaku 1 3 2 C films are laminated Is formed.
- the second RAM layer 13 4 is composed of the side surfaces of the UV hardened film 13 5, the Au interference film 13 4 D, the ZnS-Si 0 2 protective film 13 4 A, the GeSbTe recording film 13 4 B, ZnS-Si0 2 protective film 1 3 4 C, membranes of Al-Cr reflecting film 1 3 4 E are formed in the laminated structure.
- the objective lens 1336 that focuses the laser beam is controlled by a focus servo circuit (not shown), and the objective lens 1336 controls the recording film of the first RAM layer 132.
- Laser beam LA 1 in first focus state focused on 1 3 2 B and second focus state focused on recording film 13 4 B of second RAM layer 13 4 B The laser beam is switched to one of the two laser beams LA2, and data is recorded and reproduced from each of the recording films 132B and 134B in the corresponding focus state.
- the recording capacity of each layer is the standardized 4.7 GB side, the total of the two sides will be 9.4 GBZ per side, but the first RAM Considering the crosstalk caused by the optical interference between the layer 132 and the second RAM layer 134, the recording capacity of each layer is reduced to 4, 25 GB by slightly lowering the recording density. The total size of the two layers is 8.5 GB.
- the reproduced signals from the first RAM layer 132 and the second RAM layer 134 need to be at substantially the same level.
- the magnitude of this reproduced signal is the difference between the reflectance of the recording mark (amorphous portion) and the surrounding erased portion (crystal portion) (hereinafter referred to as the reflectance change amount).
- ⁇ r 1 is the reflectance change amount in the first RAM layer itself.
- 2nd RAM The amount of change in the reflectivity from the layer is determined by the fact that the incident light is transmitted through the first RAM layer, is reflected by the second RAM layer, and is transmitted again through the first RAM layer 132. This is a value obtained by multiplying the reflectance change ⁇ 2 from the layer 134 by the transmittance of the first RAM layer 132 twice.
- each parameter is defined.
- the reflectance of the crystal of the first RAM layer is r lc
- the absorption is c lc
- the transmittance is t lc
- the reflectance of the amorphous is r la
- the absorption is a la
- the transmittance is t la.
- r lc + a lc + t lc 100
- r la + a la + t la 100.
- the reflectivity r lc is set to 9% so that servo is performed electrically even when the first RAM layer 132 is in an unrecorded (crystalline state) state.
- the reflectivity r lc is better if the servo alone is taken into account, but the larger the better, the more the reflected light beam from the second RAM layer 134 returned to the objective lens 136 as described above. Expects that the intensity of the light beam reflected from the second RAM layer 134 will be considerably reduced if the intensity is too large because the power has passed through the first RAM layer 132 twice. It is presumed that it is in line with that.
- the incident light beam must pass through the first RAM layer 132 and then reach the second RAM layer 134 Therefore, the transmittance t ic of the first RAM layer 132 was set to 50%.
- the reflective film 134E is made of metal for cooling in a phase-change optical disk.
- the disk of the first RAM layer 132 is not provided with a reflection film. If the transmittance of the first RAM layer 132 is too large, the absorptance of the first RAM layer 132 decreases, and the recording sensitivity of the first RAM layer 132 decreases. There is a problem.
- the magnitude of the reproduced signal from the l c layer 1 3 2 is
- the transmission force tl is expressed as 0.5 (5 0%), ⁇ R2 becomes 24% from simple calculations.
- the second RAM layer 13 4 can record even with a small amount of light transmitted through the first RAM layer 13 2 as described above. Therefore, it is necessary to increase the sensitivity of the disk. In other words, it is necessary to set the absorption rate of the unrecorded portion (crystal state) to be large. In order to prevent the absorbed heat from escaping, it is necessary to set the thickness of the reflecting film to be thin so as to transmit the light to some extent in order to suppress the escape of the heat from the reflecting film.
- r 2c, a 2c, and t 2c are the reflectivity, absorptivity, and transmissivity of the crystalline state of the second RAM layer 134
- r 2a, a 2a, and t 2a are the amorphous state, respectively. Represents the reflectance, absorptance, and transmittance.
- the reflectance r 2a of the recording mark is higher than the reflectance r 2c of the erased state (crystal portion). It is an L to H media.
- the method of increasing the numerical aperture of the objective lens to increase the density has the following various problems.
- the spherical aberration mainly caused by the thickness error of each lens and the spacing error of each lens increases in proportion to the fourth power of the number of apertures.
- the factors that cause such aberrations include not only the accuracy of components and the accuracy of assembly and adjustment of the optical head, but also the deterioration of reliability such as aging of the drive unit and changes in various environments. Sometimes it does. For this reason, drive equipment must be more reliable than ever. The need to ensure such high reliability also leads to the disadvantage of increased manufacturing costs.
- the working distance corresponding to the distance between the part of the objective lens closest to the disk and the disk surface is determined by the numerical aperture of the optical design. Decreases in proportion to For example, when the numerical aperture is 0.60 mm, the working distance is 1.5 to 1.8 mm, whereas when the numerical aperture is about 0.85, the working distance is There is a problem that it becomes extremely narrow, 0.25 to 0.30 mm. If the working distance is short, the possibility that the objective lens will come into contact with the disk when a large external impact is applied increases the possibility of damaging the disk surface or the objective lens surface. In order to avoid this, there is a disadvantage that more advanced servo control is required.
- a method of increasing the capacity of an optical disc capable of recording, reproducing, and erasing a phase change type laser is described above with a blue laser, a high NA objective lens, and a 0.1 mm thin film.
- the method using a cover layer, the substrate thickness, and the laser wavelength are doubled on one side, and only the online capacity accessible from one side is doubled. There is an attempt at last.
- the numerical aperture NA of the objective lens is set to 0.75 to 0.85.
- the larger the NA of the objective lens the higher the price, the more difficult it is to process in manufacturing, or the lower the yield. is there.
- An object of the present invention is to provide an optical disk optimized to further increase the recording density.
- Another object of the present invention is to provide a phase-change type optical disk capable of recording, reproducing, and erasing, which is capable of increasing recording density and increasing storage capacity.
- the inventors have observed the optimal relationship between the thickness of the transparent substrate of the disc and the number of apertures of the objective lens in order to achieve a higher recording density. It is out. That is, in the present invention, the thickness of the transparent substrate is selected from the range of 0.2 mm to 0.4 mm, and the wavelength of the light beam transmitted through the transparent substrate is selected from the range of 400 nm to 420 nm. The number of apertures of the objective lens for converging the light beam is selected from the range of 0.60 to 0.75. In the case of phase-change optical discs that can be recorded, played back and erased, it is necessary to increase the mass productivity of optical discs and reduce the unit cost of the discs, as with current DVD video or DVD ROM.
- the numerical aperture NA of the optical disc is smaller than 0.60.
- the optical disc is transparent. The thickness of the layer is required not to be greater than 0.4 mm.
- the objective lens is a two-lens objective lens compared to a single lens, it is necessary to take the optical alignment of the two lenses, and the mass productivity is low and the reliability is low. There is also a problem. Further, the two-group objective lens has a problem that a spherical error easily occurs due to a thickness error generated in a transparent layer of a disc, and the working distance is short. For this reason, it is preferable that the objective lens be a single lens, that is, a one-group objective lens.
- the upper limit of the numerical aperture NA of the one-group objective lens is about 0.75 in order to secure the tilt margin of the objective lens itself, and the optical disc has a two-layer structure. In order to realize this, the thickness of the transparent layer of the optical disc must be smaller than 0.2 mm, as evident from the graph in FIG. From such a viewpoint, power,
- An optical disc is provided.
- the numerical aperture of the objective lens is substantially set to 0.65, and the thickness of the transparent substrate is set to substantially 0.3.
- An optical disk specified in mm is provided.
- a transparent substrate which is focused by an objective lens having a numerical aperture of 0.60 to 0.75 and is irradiated with a light beam having a blue wavelength of about 410 nm and a thickness of 0
- a transparent substrate defined in the range of 2 mm to 0.4 mm,
- the recording layer formed on the transparent substrate is searched by a light beam transmitted through the transparent substrate to reproduce data, record data, or erase recorded data. Recording layer,
- An optical disk is provided.
- the recording layer is reversibly changed in phase between amorphous and crystalline by irradiation with a light beam, and data is recorded and erased.
- An optical disc composed of a variable recording film is provided.
- the numerical aperture of the objective lens is set to 0.65, and the thickness of the substrate is set to 0.3 mm. Is provided.
- a first phase-change recording film which reversibly changes phase between the amorphous and the crystal by irradiation with a light beam
- the first recording film is formed, and has a first transparent substrate having a thickness defined in a range of 0.2 mm to 0.4 mm, and a blue wavelength near 41 O nm.
- a phase-change type second recording film which reversibly changes phase between the amorphous and the crystal by irradiation of the light beam;
- the first recording film is arranged such that the first transparent substrate is directed to the light beam incident side, and the light beam that has passed through the first transparent substrate and the first recording film is the second recording film.
- a first adhesive layer having a predetermined thickness for joining the two so that the recording film is irradiated, and
- a phase-change optical disc composed of
- the light beam is focused on one of the first and second phase change recording films from the incident side by an objective lens having an aperture number selected from the range of 0.60 to 0.75.
- An objective lens having an aperture number selected from the range of 0.60 to 0.75.
- a single-sided, two-layer phase-change optical disc is provided that can be illuminated and record, erase, and reproduce data on the recording film.
- the number of apertures of the objective lens is set to 0.65, and the thickness of the substrate is set to 0.3 mm.
- Optical disc Provided.
- a third recording film of a phase change type which reversibly changes phase between the amorphous and the crystal when irradiated with a light beam having a blue wavelength of around 410 nm;
- the first recording film is formed, a second transparent substrate having a thickness defined within a range of 0.2 mm to 0.4 mm, and an amorphous and a crystal formed by irradiation of a light beam.
- a phase-change type fourth recording film that reversibly changes phase between
- the third recording film is arranged so that the first transparent substrate is directed to the light beam incident side, and the light beam that has passed through the second transparent substrate and the third recording film is applied to the fourth recording film.
- a second adhesive layer having a predetermined thickness for joining the two so that the recording film is irradiated, and
- phase-change optical disk comprising: the first transparent substrate adhered to the second transparent substrate; and a single-sided two-sided two-layered phase-change optical disk joined together.
- the optical disc according to the invention of (8) wherein the objective lens has an aperture of 0.65 and the thickness of the substrate is 0.3 mm. You.
- the recording layer A method for reproducing data from an optical disk provided, comprising: generating a light beam having a wavelength selected from a range of 400 to 420 nm;
- the numerical aperture of the objective lens is substantially set to 0.65, and the thickness of the transparent substrate is set to substantially 0.3.
- a reproduction method characterized by being specified in mm is provided.
- a transparent substrate to which a light beam is applied the thickness of which is set in a range of 0.2 mm to 0.4 mm, and a recording layer formed on the transparent substrate;
- the data is reproduced by being searched by the light beam transmitted through the transparent substrate, and the data is recorded, or the data is reproduced from an optical disc composed of a recording layer from which the recorded data is erased.
- a playback method that records data on an optical disc and erases the data
- the recording layer is reversibly changed in phase between amorphous and crystalline by irradiation of a light beam, so that data recording and erasing can be performed.
- a reproduction method characterized by being made of a phase-change recording film is provided.
- the numerical aperture of the objective lens is set to 0.65, and the thickness of the substrate is set to 0.3 mm.
- a phase-change type first recording film which reversibly changes phase between the amorphous and the crystal by irradiation with a light beam
- This first recording film is formed, a first transparent substrate having a thickness defined within a range of 0.2 mm force and 0.4 mm, and an amorphous film formed by irradiation with a light beam.
- the first recording film is arranged so that the first transparent substrate is directed to the light beam incident side, and the light beam that has passed through the first transparent substrate and the first recording film is applied to the second recording film.
- a first adhesive layer having a predetermined thickness for joining the two so that the recording film is irradiated, and
- the number of apertures of the objective lens is set to 0.65, and the thickness of the substrate is set to 0.3 mm.
- a reproduction method characterized in that the reproduction method is provided.
- a transparent substrate having a thickness within a range of 0.2 mm to 0.4 mm and a recording layer formed on the transparent substrate are searched by a light beam transmitted through the transparent substrate.
- Device for reproducing data from an optical disc having a recording layer is a transparent substrate having a thickness within a range of 0.2 mm to 0.4 mm and a recording layer formed on the transparent substrate.
- a playback device for playing back data composed of
- a reproducing apparatus is provided, wherein the numerical aperture of the objective lens is substantially set to 0.65, and the thickness of the transparent substrate is set to substantially 0.3 mm. .
- the data is reproduced by being searched by the light beam transmitted through the substrate, and the data is recorded, or the data is reproduced from an optical disc composed of a recording layer from which the recorded data is erased.
- a playback device that records data on a disc and erases data
- a reproducing apparatus for reproducing data from an optical disc composed of:
- the recording layer is reversibly phase-changed between amorphous and crystalline by irradiation with a light beam to record and erase data.
- a reproducing apparatus characterized by being constituted by a phase change type recording film.
- a first phase-change recording film which reversibly changes phase between the amorphous and the crystal by irradiation with a light beam
- This first recording film is formed, a first transparent substrate having a thickness defined in a range of 0.2 mm to 0.4 mm, and a crystal and a crystal formed by irradiation of a light beam.
- a second phase-change type recording film that reversibly changes phase between
- the first recording film is arranged so that the first transparent substrate is directed to the light beam incident side, and the light beam that has passed through the first transparent substrate and the first recording film is the second recording film.
- a first adhesive layer having a predetermined thickness for bonding the two so that the recording film is irradiated, and
- a reproducing apparatus that reproduces data from a phase-change optical disc composed of an optical disc, records data on the optical disc, and erases the data
- a reproducing apparatus for reproducing data from an optical disc composed of a. According to this invention, in the invention of (22), the number of apertures of the objective lens is set to 0.65, and the thickness of the substrate is set to 0.3 mm. Provided is a reproducing apparatus characterized in that
- FIG. 1 is a cross-sectional view schematically showing the structure of a single-sided, two-layer RAM disk.
- FIGS. 2A, 2B and 2C are schematic diagrams showing the state of contamination of the optical disk surface according to the conventional example and the embodiment of the present invention, and the state of contamination of the optical disk surface according to the comparative example. It is a schematic diagram.
- FIG. 3 is a graph showing the relationship between the thickness of the transparent substrate and the coma generated by the disc tilt in the conventional example and the example of the present invention.
- FIG. 4 is a graph showing an embodiment of the optical disk of the present invention and showing a range of an allowable numerical aperture and a thickness of a transparent substrate.
- FIG. 5 is a graph showing the expected increase in the recording capacity by increasing the numerical aperture of the optical disk under the setting conditions shown in FIG.
- FIG. 6 is a cross-sectional view schematically showing the structure of an optical disk according to an example of the present invention.
- FIG. 7 is a graph showing an increase in recording capacity expected by increasing the numerical aperture of a phase change optical disc according to another embodiment of the present invention.
- FIG. 8 is a sectional view schematically showing a structure of a phase-change optical disc according to another embodiment of the present invention.
- FIG. 9 is a cross-sectional view schematically showing the first RAM layer disk before bonding the single-sided dual-layer RAM disk shown in FIG. 8.
- FIG. 10 is a cross-sectional view schematically showing the second RAM layer disk before the single-sided dual-layer RAM disk shown in FIG. 8 is bonded.
- FIG. 11 is a cross-sectional view of FIG. FIG. 2 is a block diagram showing a sputter device for forming a film on a substrate in order to manufacture a first RAM layer and a second RAM layer disk shown in FIG.
- FIG. 12 is a block diagram showing an optical disk drive device for driving a phase change optical disk according to another embodiment of the present invention.
- FIG. 13 is a waveform diagram showing a laser pulse at the time of OW in the apparatus shown in FIG.
- Figure 3 is a graph showing the relationship between the thickness of the transparent substrate and the coma aberration (converted to wavefront aberration) caused by disc tilt under each condition (numerical aperture of the objective lens).
- the amount of comma aberration on the vertical axis is determined in arbitrary units.
- the thickness of the transparent substrate is 0.6 mm
- the numerical aperture of the objective lens is 0.60
- the wavelength is 65 O nm.However, if a disk tilt of a certain unit angle occurs, The amount of generated coma is about 200 in arbitrary units. More specifically, coma can be estimated by the following proportional equation (1).
- t thickness of the transparent substrate
- N A numerical aperture of the objective lens
- ⁇ wavelength of the light source
- the wavelength is shortened from 65 O nm to 410 nm, and unnecessary coma aberration is increased by increasing the aperture. You can see that it goes. Since the coma aberration increases in proportion to the disc tilt, the coma can be reduced to a lower level as a whole by manufacturing a disc with a smaller tilt than the conventional optical disc. This is certainly possible, but in this case, the cost of manufacturing the disk is high, and if this results in a high selling price, disadvantages arise. This conflicts with the ultimate goal of disseminating higher density optical disc systems. Therefore, the amount of tilt of the disk is as small as possible with the coma aberration, assuming that it is equal to the conventional level. It is necessary to consider measures to reduce the impact.
- Fig. 3 As can be clearly seen, in order to suppress coma aberration at the same level as in the DVD-ROM system, it is necessary to reduce the thickness of the transparent substrate and to limit the range of the number of apertures. The two must be combined. Specifically, it is necessary to set the numerical aperture to be approximately 0.60 or more and 0.75 or less, and the transparent substrate thickness to be approximately 0.2 mm or more and 0.4 mm or less. Also, not all combinations are possible in this range, and the combination of the transparent substrate thickness and the numerical aperture capable of suppressing coma below a predetermined value is limited to the range shown by the oblique lines in FIG.
- Fig. 5 shows the estimated recording capacity under such conditions.
- the actual recording capacity is determined by detailed design of the minimum bit length of the optical disk, the track pitch, or the modulation method used in the drive system, etc. Although it can be fixed, it can be roughly estimated as a preliminary study.
- Figure 5 shows the estimated storage capacity in this way.
- the diameter of the collection spot is reduced in proportion to wavelength and inversely to numerical aperture.
- the increase in recording capacity is almost proportional to the density of the optical disk in the radial and circumferential directions (how to fill it). It can be predicted that it is almost proportional to the square of. In other words, the wavelength 2
- the increase in recording capacity is expected in proportion to the power and inversely proportional to the square of the number of openings.
- Figure 5 shows the calculation based on the current DVD-ROM based on the proportional conversion of wavelength and aperture. As is evident from Fig. 5, the proposed method uses a disk of the same diameter as the DVD-ROM disk, with 12 to 18 GB per side on one side. Realization of such large capacity can be expected.
- optical disk drive to which the present invention is applied is described in, for example, the document “Optical Disk Technology” (Noboru Murayama et al., Radio Technology, 1989). However, as described above, only the configuration of the objective lens and the wavelength of the light source are different, and the other configurations are the same.
- the RAM disk drive system described later and the optical disk drive described above have substantially the same configuration, and thus the optical disk to which the above-described embodiment is applied. Please refer to this description for an overview of the disk drive system.
- the objective lens is a so-called single lens, like a conventional objective lens having an aperture of 0.60 or less, and a predetermined number of lens actuators. It is used by fixing the position.
- the number of openings is 0.65.
- the objective lens is not limited to a single lens, but may be configured as a combination lens of a plurality of lenses as long as the cost is low and the reliability is high.
- the light source is a semiconductor laser having a wavelength of 400 nm, which is basically used in the same manner as a conventional red semiconductor laser or infrared semiconductor laser.
- prism and lens Optimum coating specifications for optical components such as are also adopted.
- the optical disk 1 shown in FIG. 6 includes a transparent substrate 2 and a PC (polycarbonate) substrate 3.
- the PC substrate 3 is formed in advance with a pit that carries information similarly to the substrate of a read-only disk such as a CD, and has a thickness of 0.9 mm.
- an aluminum thin film 5 is adhered to the pit 4 side of the PC substrate 3 by vacuum evaporation in order to increase the reflectance.
- a transparent substrate 2 having a thickness of 0.3 mm is formed on the pit side of the PC substrate 3.
- a 0.3 mm thick ultraviolet ray curable resin layer is formed on a PC substrate 3 on which aluminum is deposited by a spin coating method, or a 0.3 mm thick transparent sheet is formed.
- the transparent substrate 2 is made by a method in which the transparent substrate 2 is formed by an adhesive or an ultraviolet curing adhesive.
- the diameter of the light beam on the disk surface is about 0.34 mm as shown in Fig. 2B, and the influence on the surface contamination is relatively small. Can be lowered.
- the working distance is about 1.7 mm, which makes it possible to design the servo system while preventing collision between the objective lens and the disk.
- phase-change optical disk according to another embodiment of the present invention will be described.
- a single-sided, two-layer RAM disk will be described with reference to FIGS.
- a phase change optical disk according to another embodiment of the present invention has been optimized in consideration of the advantages and disadvantages of increasing the capacity of the phase change optical disk. That is, the wavelength of the semiconductor laser is set to a blue wavelength near 410 nm, the NA of the objective lens is set to be larger than 0.6, smaller than 0.75, and the thickness of the substrate is reduced. It is set to be thicker than 0.2 mm and thinner than 0.4 mm. By such an optimization, it is possible to provide a phase-change optical disk capable of high-density recording and capable of forming a single-sided, dual-layer RAM.
- the present invention uses a blue laser having a wavelength of 410 nm, an objective lens having an NA of 0.65, and a circular substrate having a thickness of 0.3 mm.
- a blue laser having a wavelength of 410 nm
- an objective lens having an NA of 0.65
- a circular substrate having a thickness of 0.3 mm.
- the use of a single-layer CD (1 .0 mm) of the current product makes it possible to achieve an overall thickness of about 1.2 mm even with a 130 mm diameter disk. 2 mm thick), the same mechanical accuracy or the same rigidity as the double-sided laminated DVD (thickness after lamination is 1.2 mm) can be obtained.
- this disc can record / reproduce / erase about 12 GB on one layer on one side, 24 GB on two layers on one side, and 48 GB on four layers on both sides. Possible user capacity can be secured.
- FIG. Figure 7 shows the calculated value of the one-sided capacity (vertical axis) of an optical disk with a diameter of 12 O mm with respect to the NA (horizontal axis) of the objective lens when the laser wavelength was selected to be 410 nm. It is shown.
- the converted capacity 1 is calculated based on the second-generation DVD-RAM for which the standard is currently in progress.
- the second-generation DVD-RAM is a disk having a diameter of 120 mm with a phase-change recording film, a user capacity of 4.7 GB on one side, and a laser wavelength of 65 O.
- the objective lens NA is 0.6 (NAr)
- the substrate thickness is 0.6 mm.
- the laser wavelength power from S650 nm ( ⁇ r) is replaced with the power of 410 nm (; Lb), and the NA of the objective lens is 0. 6 (NA r) force, etc.
- the single-sided capacity when the NA was changed in place of the higher NA (NA b) was calculated (see this calculation). Is simply the ratio of the laser wavelength to the NA of the objective lens, and the areal density (in other words, the capacity of one side) increases by the square, and is therefore expressed by the following equation (2).
- NA r 0.60
- NA b a variable that is a norameter
- ⁇ r 650 nm
- b 410 nm.
- the conversion capacity 2 expressed by the following equation (3) is, assuming a single-sided, two-layer disk, the difference between the data of the first RAM layer disk and the data of the second RAM layer disk. Lost talk is predicted, so the capacity conversion when the recording density is relaxed with some margin This is a calculation example.
- Equivalent capacity 2 Equivalent capacity 1 X 0.84 4... (3) According to Equivalent capacity 1, the laser wavelength is changed to 6500 nm, and the other side is changed to 410 nm, and the capacity of one side is 15 GB. If it is set to 20 GB, it turns out that the NA of the objective lens is 0.67 and 0.78. However, in this case, as described above, a 0.1 mm thick substrate must be used, so that a single-sided, dual-layer RAM disk cannot be realized.
- the conversion capacity 2 when used, a single-sided, two-layer RAM is assumed, and the objective lens NA can be easily manufactured by ordinary manufacturing technology, and can be purchased at a low cost. Assuming 65, the user capacity on one side of a disk with a diameter of 120 mm is found to be 12 GB.
- FIG. 3 shows the coma aberration when the thickness of the substrate is plotted on the horizontal axis when the NA of the objective lens is set as the illuminator at a wavelength of 410 nm. ing.
- Coma is represented by equation (1).
- the case of a 4.7 GB DVD-RAM (wavelength: 65 nm) is shown by a dotted line, but the coma aberration is almost the same as the current DVD-RAM of 4.7 GB.
- the thickness of the substrate is uniquely determined when the NA is changed using a laser with a wavelength of 410 nm.
- the substrate thickness becomes close to 0.1 mm.
- the NA of the objective lens it is assumed that 0.65, which is easy to manufacture and inexpensive, is available.
- the substrate thickness of 0.3 mm is appropriate.
- a substrate thickness of 0.3 mm can be produced by injection molding of a resin material as before, and a single-sided double-layer RAM has a thickness of about 0.6 mm, and a single-sided double-layer RAM is also used.
- the thickness becomes 1.2 mm, so that the thickness can be set to the same thickness as the current product CD or two-sheet DVD.
- sufficient mechanical precision and mechanical strength can be obtained as a product.
- the NA of the objective lens is set to 0.60 to 0.75, which is relatively easy to manufacture and can be obtained at low cost. If the substrate thickness is set from 0.2 mm to 0.4 mm so that the coma can be suppressed to the level of the current DVD-RAM based on the graph force in Fig. 3, large capacity can be achieved. In addition, sufficient mechanical accuracy can be obtained by bonding four sheets when a single-sided, dual-layer RAM is used.
- the substrate thickness is set to 0.3 mm
- the objective lens NA is set to 0.65
- 410 nm Recording and reproduction with the blue laser will be described.
- FIG. 8 is a perspective view showing an optical disc according to another embodiment made under the above-described conditions, and FIGS. 9 and 10 are shown in FIG.
- FIG. 1 is a cross-sectional view schematically showing a structure of an optical disk to be used.
- the single-sided two-layer optical disk includes a disk 27 having a first RAM layer (hereinafter, simply referred to as a disk 27 of the first RAM layer) and a second disk.
- 2 Disk 28 having a RAM layer (hereinafter, simply referred to as disk 27 of the second RAM layer) has a structure in which it is joined by a UV-curable resin film 29 as a joining layer. ing.
- a clamp is provided so that the optical disk can rotate.
- a clamping area 21 is provided.
- a lead-in area 22 is provided in an inner peripheral area around the clamping area 21 to start a data search by a pick-up head (not shown).
- a lead-out area 23 is provided on the outer periphery.
- Information from the lead-in area 21 to the read-out area 23 is defined as an information recording area 24 in which information is recorded.
- the read-in area 22 and the read-out area 2 are also defined.
- the area between the three areas is defined as a data write area 25 where data is written.
- FIG. 9 the structure of the disks 27 and 28 of the first and second RAM layers will be described in detail with reference to FIGS. 9 and 10.
- S i0 2 protective film 1 0 2 2, GeSbTe phase change recording film 1 0 3 and ZnS - have have a structure laminated S i0 2 protective film 1 0 4 in the order of this.
- ZnS-Si0 2 protective film 1 0 2 and 1 0 4 ZnS and Si0 mixed film consisting of the second mixed material (hereinafter, simply referred to as ZnS-Si0 2 protective film.)
- the protective film 1 0 2 the phase change recording film 1 0 3 and the protective film 1 0 four ⁇ Since the transmittance of the first RAM layer 105 is set to 50%, the metal reflection film to be provided in a normal single-layer phase-change optical disc is 5 does not.
- the disk 28 of the second RAM layer is composed of a reflective film 111 made of Al-Cr on a transparent substrate 111 made of 0.6 mm thick polycarbonate.
- ZnS-Si0 2 mixture consisting film dielectric protective film 1 1 3 is deposited, thereon, Ri by the morphism irradiation of the laser beam or the like, reversibly changes phase between amorphous and crystalline , for example, ternary alloys made of phase change recording film 1 1 4 of GeSbTe is laminated again, the dielectric protective layer 1 1 5 consisting of ZnS-Si0 2 mixture film further has a L-to H media It has a structure in which a translucent film 116 made of Au is laminated as a translucent interference film for performing the above operation. In here, ZnS-Si0 2 protective film 1 1 3, 1 1 5 are likewise. ZnS and Si0 2 mixed film consisting of a mixture material (hereinafter, simply referred to as ZnS-Si
- the phase-change recording film 114 becomes amorphous by melting and quenching by laser beam irradiation, and at this time, the dielectric protection films 113 and 115 become the recording film. It has the function of preventing holes from opening due to evaporation of 114, that is, the function of protecting the recording film from heat.
- the upper dielectric layer 115 is designed to optically enhance during signal reproduction due to the synergistic effect of the translucent Au layer 116 and the metallic reflective layer 112, and usually has a large thickness. It is 50 OA— 3 0 0 Set to OA.
- the phase change recording film 114 is usually designed to be very thin because it needs to be melted by irradiation with a laser beam, and is set to 50 to 30 OA.
- the dielectric protective film 1 13 below the phase change recording film 1 1 4 is formed on the metal reflective film 1 1 2 in order to rapidly cool the heat of the recording layer melted by laser beam irradiation as much as possible to become amorphous. It is necessary to have a structure that allows heat to escape, and it is thin and typically has a thickness of about 5 OA to 30 OA.
- the lower dielectric layer 113 is set to 30OA-300OA.
- the thickness of the metal reflective film 112 is usually set to be not less than 50 OA and about 300 OA in order to improve the enhancement of the reproduction signal and the escape of heat.
- 100 A may be set to 500 A.
- the translucent Au film 116 needs to have an appropriate transmission and reflection because it interferes with the laser beam transmitted through the Au film and the reflected light beam from the recording film 114 to enhance it.
- the film thickness is set to 20 OA from 20 OA.
- the current 4 GB The recording density is 2.553 times higher in cotton density than the 7 GB surface, but it can be converted to linear density by 1.6 times the square root.
- the current 4.7 GB RAM disk has a track pitch of 0.6 / Zm, so the 12 GB disk track pitch is 0.375 ⁇ .
- FIG. 11 shows a sputter device in which a single-sided, two-layer phase-change optical disk according to another embodiment of the present invention is manufactured.
- a continuous groove with a diameter of 120 mm, a thickness of 0.3 mm, and a surface of 0.375 / m width is formed on the rotatable disk-shaped base 8 shown in Fig. 11.
- the disc substrate 9 made of carbonate was set, and the inside of the vacuum sputtering device 30 was evacuated to 10 -6 torr by the vacuum turbo pump 12.
- numeral 11 indicates the exhaust system valve.
- the first RAM layer disk shown in Fig. 9 was fabricated. With the rotating base 8 rotated at 60 rpm, the Ar gas introduction valve 10 was opened, and Ar gas was introduced into the snutter device.The exhaust system capacity was maintained as it was. Then, the Ar gas flow rate is adjusted by a mass flow controller (not shown) and set so that the vacuum pressure in the device becomes S5X10-3 torr. Was done.
- Valve 1 0 is closed, and through the exhaust system 1 2, after the residual Ar gas and ZnS / Si0 2 molecules within the device is one ⁇ evacuated again, Pal Bed 1 0 is opened has been Ar gas Introduced, the Ar gas pressure in the spatula was set to 5 X 10-3 torr.
- Switching switch 17 The compound composition target of 17 GeSbTe is switched to the electrode 14 a side of 14 b, the power supply 16 is turned on, and the power power of 200 W S GeSbTe target Supplied to After about 1 minute of Prin spa jitter, is shut ter 1 4 c is opened directly above the target, deposition of GeSbTe phase change recording film to ZnS-Si0 2 protective film is started.
- This sample disk 9 was taken out of the sputter device 30.
- This first RAM layer disk is subjected to an initial crystallization device (not shown), and the entire surface is crystallized with a high-power Ar laser. Then, a laser beam having a wavelength of 410 nm is irradiated from the substrate side to obtain a reflectance. Was measured. In this measurement, the reflectance from the crystal part was about 8%. In exactly the same way, another disk of the same first RAM layer was fabricated.
- the rotating base 8 in the vacuum sputtering device 30 has a diameter of S130 mm, a thickness of 0.3 mm, and a track pitch.
- a polycarbonate substrate with a 0.375 ⁇ m continuous groove was set.
- the inside of the vacuum sputtering device 30 was evacuated to a vacuum of 10 -6 torr by the vacuum turbo pump 12.
- the Ar gas introduction valve 10 was opened, and Ar gas was introduced into the sputtering device.
- the capacity of the exhaust system is maintained as it is, the flow rate of Ar gas is adjusted by a mass flow controller (not shown), and the degree of vacuum in the device becomes 5 XI 0 -3 torr Was set to Switching switch 17 Power S AlCr target 15b Switched to the electrode 15a side, RF power supply 16 power supply 20 0 W of power was supplied to AlCr target 15b. After about 1 minute of pre-sputtering, the shutter 15C was opened and the AlCr reflective coating was started. 50 seconds after the start of film formation, the RF power was turned off, the shutter 15C was closed, and an AlCr reflective film was formed on the substrate with a film thickness of 30 OA.
- the valve 10 is opened again, and Ar gas is introduced into the sputtering device, not shown.
- the mass flow controller was adjusted and the inside of the sputter device was set to 5 XI 0 -3 torr.
- the scan I pitch 1 7 instead Ri switching is supplied to the ZnS-Si0 2 Target Tsu preparative 1 3 b of the electrode 1 3 a is replaced Ri switch to side RF power 6 0 0 W power S ZnS-S10 2 Target Tsu DOO Was done.
- the switching switch 17 is switched to the electrode 14a side of the GeSbTe compound composition target 14b, the power supply 16 is turned on, and the power of 200 W is supplied to the GeSbTe. Supplied to target. After about 1 minute of pre-sputtering, shutter 14c immediately above the target is opened and the The formation of the GeSbTe phase change recording film on the risk substrate 9 was started. After 2 0 seconds elapsed from the start of film formation, it is the RF power source 1 six OFF, has been formed on the ZnS-Si0 2 film GeSbTe recording film thickness 1 0 0 A. Again, valve 10 was closed, and the residual Ar gas and GeSbTe molecules in the snorter device were exhausted.
- valve 10 was opened and Ar gas was introduced into the snorter device 30.
- Ar gas pressure is 5 X 1 0 -3 t orr is adjusted, electrodes 1 3 a side of the scan I Tutsi 1 7 again changed Ri switching ZnS-Si0 2 target 1 3 b is replaced Ri switch to, Pa Wa one RF power supply 1 6 power et 6 0 0 W is supplied to the ZnS-Si0 2 target 1 3 b.
- About 1 minute of Prin scan Roh finisher jitter over 1 3 c is opened again ZnS- Si0 2 of the deposition after the other has been started.
- the RF power supply 16 was provided under the Au target 12 b by the switching switch 17 RF power of 13.56 MHz was supplied to the electrode 12a, and RF power of 13.56 MHz was supplied to the electrode 12a, and sputtering of Au target with Ar gas was started. After Prin spa jitter of about 1 minute, it is deposited in the Target Tsu by preparative shut ter 1 2 c immediately above is opened, ZnS-Si0 2 Au optical interference film thickness on of 1 0 0 A The RF power supply 16 is turned off and the shutter 1 2 c has been closed.
- the second RAM layer sample disk 9 produced by this normal process was taken out of the sputtering apparatus 30. From the above description, the film structure of this disk is composed of the substrate, AlCr (300 A), ZnS-Si02 (55 OA), GeSbTe (100 A), ZnS-Si02 And Au (100 A).
- the second RAM layer disk was also subjected to an initial crystallization device (not shown), and after the entire surface of the disk was crystallized, the reflectance was measured with a semiconductor laser having a wavelength of 410 nm. In this measurement, the reflectance from the crystal was 13%.
- UV curable resin it by the scan Pina one not shown, the 4 0 mu thickness ⁇ on ZnS-Si0 2 film of the 1 RAM layer disk is entirely uniformly applied, then the 2 RAM layer The disk is overlaid so that the Au interference film side of the disk is in contact with the UV resin, and then 800 W of UV light is irradiated for 20 seconds from the substrate side of the first RAM layer disk.
- the UV resin has been cured.
- the prototype phase-change optical disk sample described above was mounted on an optical disk drive shown in Fig. 12 to evaluate its performance.
- the sample disk 31 is rotated by the spindle motor 32 to a predetermined rotational speed. Since a single-sided dual-layer DVD-RAM is assumed this time, the radius of the disk is set so that the relative speed between the disk 31 and the optical head 33 is kept constant at 8.2 m / s. A constant linear velocity system is used, in which the rotational speed changes successively at different positions.
- a predetermined signal is input from the input device 36, and is modulated by the modulation circuit 35 into 1, 0 signals by 8Z16 modulation in the case of a DVD-RAM, for example.
- the modulated digital signal was sent to the laser driver 37, and the data was written on the disk sample 31 by turning on and off the laser of the optical head. Since there is no commercially available blue semiconductor laser, an Ar gas laser with a wavelength of 41.4 nm is provided instead of the semiconductor blue laser.
- the NA of the objective lens is 0.65.
- the laser power is raised (at power Pw) to the part to be recorded, and the recording film is melted and quenched to form an amorphous phase. Was changed to.
- the laser power was set to the middle level (laser power pe ) for the portion where data was to be erased, and the erased portion of the recording film was heated to a temperature higher than the crystallization temperature to be crystallized.
- the laser power ⁇ ⁇ is the reproduction power at the time of reproduction.
- the data written on the sample disk (amorphous mark) has a different reflectance from the surrounding crystal part when it is regenerated, so scanning a weak constant power disk will result in a difference in the amount of reflected light.
- reference numeral 43 denotes a servo control system, which controls the laser driver 37 during recording with a laser, and, for example, during recording and reproduction, the linear motor 34 through the control system. A predetermined radius position is accessed by the linear motor drive control system 46.
- the objective lens actuator provided in the optical head 33 is controlled via the focus drive control system 44 and the track drive control system 45 so that the disk can be used during recording and playback. Control to follow the runout and eccentricity of the track.
- the recording density was increased to 1.6 times the linear density. Need to be packed. Since the track pitch has already been set to 0.375 m, the bit pitch is reduced to the same value as the bit pitch. The bit pitch on the 4.7 GB Z plane must be recorded at 0.175 / m, with a force of 0.28 jum. To form the shortest mark 3T only for the convenience of measuring the reproduction CZN ratio (Carrier to Noise Ratio) later, it is sufficient to record at a duty of 50% with a frequency of 20.8 MHz. If the CN ratio is measured by a spread spectrum analyzer during playback after recording, the value of the playback signal can be evaluated based on the measured CN ratio.
- a disk with a thickness of approximately 0.6 mm was obtained by laminating a disk with a thickness of 0.3 mm on one side and two sides together.
- the focus servo is applied by following the runout (the runout acceleration when rotating at a linear speed of 8.2 m / s) around the periphery of the drive device. The following judgment was made. In fact, for a 0.6 mm thick single-sided dual-layer RAM disk, focus servo was applied on the inner circumference side, but no servo was applied on the outer circumference side.
- the signal was recorded at a 20.8 MHz duty ratio of 50%, the recorded signal was reproduced with a reproduction light of 1 mW, and the C / N ratio was measured.
- the recording power Pw power S was set to 8 mW, and the erasing power Pe was set to 4 mW.
- the playback CZN ratio was 53 dB both. there were.
- the surface was turned over and the same shortest mark was recorded on the other side of the two-layer disc, and the reproduction CZN ratio was measured. The result was the same.
- the phase-change optical disk of the present invention when the laser wavelength is 41 O nm blue, the substrate thickness is 0.3 mm, and the NA of the objective lens is 0.65.
- the NA of the objective lens was set to 0.60 to 0.75, which is relatively easy to manufacture and can be obtained at low cost.
- the substrate thickness is set to 0.2 mm to 0.4 mm so as to suppress coma to the level of the current DVD-RAM, a large capacity can be achieved and a single-sided dual-layer RAM It is easy to guess that sufficient mechanical accuracy can be obtained by bonding four sheets when they are done.
- the embodiment has been described using a phase-change recording film that reversibly changes in phase between amorphous and crystalline as a rewritable recording medium, but the recording medium is not limited to this.
- the same effect can be expected even with a magneto-optical recording film.
- the thickness of the transparent substrate is selected from the range of 0.2 mm to 0.4 mm, and the wavelength of the light beam transmitted through the transparent substrate is selected from the range of 400 to 420 nm.
- the objective lens for converging the optical beam is selected from the range of 0.60 to 0.75.
- the signal reproduction characteristics are less deteriorated due to the contamination of the disk surface, and the objective is Lens. Therefore, the cost of parts and the cost of assembling the optical head using this objective lens do not increase, and the reliability of the objective lens is easily ensured, and the working distance is reduced. This will be sufficient.
- the blue wavelength of 410 nm is used as the laser wavelength
- the substrate thickness is 0.3 mm
- the NA of the objective lens is As described above in the case of 0.65, a laser with a wavelength of 410 nm is used. If the substrate thickness is set to 0.75 mm and the substrate thickness is set to 0.2 mm to 0.4 mm so that the coma can be suppressed to the level of the current DVD-RAM, the capacity can be increased. It is possible, and sufficient mechanical accuracy can be obtained by bonding four sheets when a single-sided dual-layer RAM is used.
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Optical Head (AREA)
- Optical Recording Or Reproduction (AREA)
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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KR1020017004171A KR20010075534A (ko) | 1999-08-31 | 2000-08-31 | 광디스크와 이 광디스크로부터 데이터를 재생하는 방법 및장치 |
US09/814,700 US20010012257A1 (en) | 1999-08-31 | 2001-03-23 | Optical disk and method of apparatus for reproducing data from the same optical disk |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP24657799 | 1999-08-31 | ||
JP11/246577 | 1999-08-31 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/814,700 Continuation US20010012257A1 (en) | 1999-08-31 | 2001-03-23 | Optical disk and method of apparatus for reproducing data from the same optical disk |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001016947A1 true WO2001016947A1 (fr) | 2001-03-08 |
Family
ID=17150499
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2000/005932 WO2001016947A1 (fr) | 1999-08-31 | 2000-08-31 | Disque optique, procede et appareil de lecture de donnees dudit disque |
Country Status (3)
Country | Link |
---|---|
US (1) | US20010012257A1 (ja) |
KR (1) | KR20010075534A (ja) |
WO (1) | WO2001016947A1 (ja) |
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KR100870106B1 (ko) | 2006-03-21 | 2008-11-25 | 제일모직주식회사 | 메틸메타크릴레이트-아크릴로니트릴-부타디엔-스티렌공중합체 수지를 이용한 광디스크 |
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US6596367B2 (en) | 2000-09-21 | 2003-07-22 | Koninklijke Philips Electronics N.V. | Optical disc |
WO2002025647A1 (en) * | 2000-09-21 | 2002-03-28 | Koninklijke Philips Electronics N.V. | Optical disc |
US7368222B2 (en) | 2001-01-16 | 2008-05-06 | Dphi Acquisitions, Inc. | Optical data storage media with enhanced contrast |
WO2002056310A3 (en) * | 2001-01-16 | 2003-02-27 | Dataplay Inc | First-side dual-layer optical data storage disk and method of manufacturing the same |
US6908725B2 (en) | 2001-01-16 | 2005-06-21 | Dphi Acquisitions, Inc. | Double-sided hybrid optical disk with surface topology |
WO2002056310A2 (en) * | 2001-01-16 | 2002-07-18 | Dataplay, Inc. | First-side dual-layer optical data storage disk and method of manufacturing the same |
EP1251499A3 (en) * | 2001-03-28 | 2006-10-25 | TDK Corporation | Readout method and apparatus for optical information medium |
US7496019B2 (en) | 2001-04-20 | 2009-02-24 | Tdk Corporation | Information readout method for non mask layer type optical information medium |
US7859968B2 (en) | 2001-04-20 | 2010-12-28 | Tdk Corporation | Information readout method for non mask layer type optical information medium |
US7142496B2 (en) | 2001-10-02 | 2006-11-28 | Matsushita Electric Industrial Co., Ltd. | Optical information recording method, device, and recording medium with plural recording layers |
US7292525B2 (en) | 2001-10-02 | 2007-11-06 | Matsushita Electric Industrial Co., Ltd. | Optical information recording method and apparatus for multiple recording layer medium |
US7492687B2 (en) | 2001-10-02 | 2009-02-17 | Panasonic Corporation | Optical information recording method, optical information recording and reproducing device, and optical information recording medium |
US7187506B2 (en) | 2004-07-02 | 2007-03-06 | Matsushita Electric Industrial Co., Ltd. | Actuator device, optical disk device, and information playback device |
Also Published As
Publication number | Publication date |
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US20010012257A1 (en) | 2001-08-09 |
KR20010075534A (ko) | 2001-08-09 |
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