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884 results about "Recording density" patented technology
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Recording density. The amount of data that can be stored in a unit length of magnetic tape, usually expressed in bits per inch or characters per inch.
Optical information processing equipment and semiconductor light emitting device suitable therefor
An information processor of a high reliability and a high recording density, and a blue color, blue-violet color and violet color based semiconductor light emitting device operable at a low threshold current density, used for the same, are provided. An optical information processor of a high reliability and a high recording density enables a moving picture, such as a high-definition television picture, to be recorded and reproduced satisfactorily. A barrier layer in a quantum-well active layer of a semiconductor light emitting device is doped with n-type impurities at a high density. Alternatively, the face orientation of a quantum-well active layer of a semiconductor light emitting device is a plane inclined from the (0001) plane, whereby the threshold current value of the semiconductor light emitting device can be decreased. The semiconductor light emitting device is typified by a gallium nitride based compound semiconductor laser device.
Owner:USHIO OPTO SEMICON
High recording density magnetic recording medium and recording/reproduction mechanism for the same
ActiveUS20180350398A1Improve recording densityMaintain good propertiesRecord information storageManufacture of flux-sensitive headsUltrasound attenuationRefractive index
A refractive index nL and an attenuation rate kL of a magnetic layer are obtained by irradiating linearly polarized light at an irradiation angle of 70° from a lengthwise direction of the magnetic layer to the surface of the magnetic layer, and a vertical reflectance RL during vertical incidence of the linearly polarized light in the lengthwise direction is obtained based on nL and kL. A refractive index nT and an attenuation rate kT of the magnetic layer are obtained by irradiating linearly polarized light at an irradiation angle of 70° from a width direction of the magnetic layer to the surface of the magnetic layer, and a vertical reflectance RT during vertical incidence of the linearly polarized light in the width direction is obtained from nT and kT. If a variation rate A (%) of RL and RT is A=|RL / RT−1|×100, the relationship A≤10% is established.
Owner:MAXELL HLDG LTD
Magnetic recording medium
InactiveUS20060187589A1High reproductive outputHigh outputRecord information storageManufacture of flux-sensitive headsMetallurgyMicrometer
Provided is a magnetic recording medium capable of achieving high reproduction output in a short wavelength region. The magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on a nonmagnetic support. The magnetic layer has a squareness ranging from 0.6 to 1.0 in a perpendicular direction, and the magnetic recording medium is employed for recording a magnetic signal on the medium in a longitudinal direction at a linear recording density of equal to or greater than 300 Kbpi using a recording head with a gap length of equal to or less than 0.3 micrometer, and reproducing the magnetic signal using a magnetoresistive head with a shield spacing of equal to or less than 0.2 micrometer.
Owner:FUJIFILM CORP +1
Magnetic disk and method of manufacturing the same
ActiveUS20100261039A1Increased durabilityImprove reliabilityRecord information storageManufacture of flux-sensitive headsPerfluoropolyetherElectrical polarity
Disclosed is a magnetic disk that has excellent durability, particularly excellent LUL durability, and excellent alumina resistance and has a high level of reliability under a low flying height of a magnetic head involved in a recent tendency toward a rapid increase in recording density and a very severe environment resistance requirement due to diversified applications. A magnetic disk (10) comprises a substrate (1) and at least a magnetic layer (6), a carbon-based protective layer (7), and a lubricating layer (8) provided in that order over the substrate (1). The lubricating layer (8) contains a compound that has a perfluoropolyether main chain in the structure thereof and has an aromatic group and a polar group at the end of the molecule.
Owner:WESTERN DIGITAL TECH INC
Perpendicular magnetic recording medium and manufacturing process therefor
InactiveUS6387483B1Improve perpendicular orientation of perpendicularReduce noiseMagnetic materials for record carriersBase layers for recording layersPerpendicular magnetizationEngineering
It is intended to reduce the media noise, and to improve the recording density dependence of read output voltage. The present invention provides a perpendicular magnetic recording media and its manufacturing process, wherein a perpendicular magnetic recording medium comprises a soft magnetic underlayer film and a perpendicular magnetizing film, these films being formed on a substrate in this order, a smoothness control film such as Cr film, being inserted between the substrate and the soft magnetic underlayer film. Therefore, perpendicular orientation and surface smoothness are improved for the perpendicular magnetizing film laminated on the smooth surface of the soft magnetic underlayer film. As the perpendicular orientation is improved for the perpendicular magnetizing film, the initial layer is reduced, thereby media noise being lowered and recording density dependence of read output voltage being improved. In addition, as the surface smoothness is improved for the perpendicular magnetizing film, sliding characteristics of a recording / reproducing head is also improved, thereby this also lowering the media noise.
Owner:WD MEDIA SINGAPORE PTE
Perpendicular magnetic recording medium and its manufacturing method
InactiveUS20130040167A1Suppress interferenceIncrease in ultra-high recording densityRecord information storageCoating by sputteringSputteringAlloy
It is aimed to provide a perpendicular magnetic recording medium capable of dealing with an ultra-higher recording density than before and its manufacturing method.The present invention concerns a perpendicular magnetic recording medium including at least a seed layer made of noncrystalline ceramic, a crystalline orientation control layer and a magnetic layer made of a material mainly containing a FePt alloy in this order on a substrate. This perpendicular magnetic recording medium is suitably manufactured by forming at least the seed layer, the orientation control layer and the magnetic layer made of the material mainly containing the FePt alloy in this order on the substrate by sputtering, wherein the magnetic layer is formed at a predetermined temperature of 500° C. or less.
Owner:WD MEDIA SINGAPORE PTE +1
Perpendicular magnetic recording medium and process for manufacture thereof
ActiveUS20110212346A1Improve coercive forceIncrease forceProtective coatings for layersPretreated surfacesIn planeRecording density
An object of the present invention is to provide a perpendicular magnetic recording medium the SNR of which is improved by reducing noise thought to be due to an auxiliary recording layer so that a higher recording density can be achieved, and a method of manufacturing the same.In order to achieve the above object, a representative configuration of a perpendicular magnetic recording medium 100 according to the present invention includes, on a base, at least a magnetic recording layer 122 having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a non-magnetic split layer 124 disposed on the magnetic recording layer 122 and containing Ru and oxygen; and an auxiliary recording layer 126 that is disposed on the split layer 124 and that is magnetically approximately continuous in an in-plane direction of a main surface of the base 110.
Owner:WESTERN DIGITAL TECH INC
Lubricant for magnetic disc, magnetic disc and method of producing the same
ActiveUS20120148875A1Organic chemistryRecord information storageEnvironmental resistancePerfluoropolyether
A magnetic disk with which further reduction of magnetic spacing can be realized and which has high reliability under such circumstances of a lower floating amount of a magnetic head involved in the recent rapid increase in recording density and of extremely severe environmental resistance involved in diversification in use applications is provided.In a magnetic disk in which at least a magnetic layer, a protective layer, and the lubrication layer are sequentially provided on a substrate, the lubrication layer contains a lubricant compound for a magnetic disk, having a perfluoropolyether main chain in the molecular structure and a structure indicated as follows at a position close to the center of the molecule:-0-CH2—CH(OH)—CH2—CH2—CH(OH)—CH2-0-or-0-CH2—CH(OH)—CH(OH)—CH2-0-
Owner:WESTERN DIGITAL TECH INC
Perpendicular magnetic recording medium
InactiveUS20110223446A1Improve recording densityImprove signal-to-noise ratioRecord information storageMagnetic recordingRecording layerRecording density
An object of the present invention is to provide a perpendicular magnetic recording medium the SNR of which is further improved while a high coercive force Hc is secured so that a higher recoding density can be achieved.The structure of a perpendicular magnetic recording medium 100 according to the present invention includes, on a base, at least a first magnetic recording layer 122a having a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape; a non-magnetic split layer 122b containing Ru disposed on the first magnetic layer; and a second magnetic recording layer 122c that is disposed on the split layer and that has a granular structure in which a non-magnetic grain boundary portion is formed between crystal particles grown in a columnar shape, wherein the first magnetic layer and the second magnetic layer contain oxides that form the grain boundary, and when an oxide content of the first magnetic layer is represented by A and an oxide content of the second magnetic layer is represented by B, a relationship between the oxide contents A / B is in the range of 0.5<A / B<1.0.
Owner:WESTERN DIGITAL TECH INC
Magnetic recording medium with guard layer between auxiliary and magnetic recording layers and manufacturing method of the magnetic recording medium
ActiveUS8605388B2Improve recording densityThin thicknessRecord information storageDisk carriersMagnetizationNon magnetic
It is an object to manufacture magnetic recording media with the high recording density. Since nonmagnetic portions (8) with a predetermined pattern are formed in a recording auxiliary layer (4) formed on a magnetic recording layer (3), it is possible to actualize a magnetic recording medium where magnetic portions (7) and the magnetic recording layer (3) immediately below the portions (7) are recording units. The nonmagnetic portions (8) are formed by non-magnetization using ion implantation, and it is thereby possible to manufacture magnetic recording media with the high recording density.
Owner:WESTERN DIGITAL TECH INC +1
Information recording method, reproducing method, and recording/reproducing method utilizing holography
InactiveUS7321541B2Improve recording densityIncrease recording capacityRecord information storageDigital storageSpatial light modulatorRecording density
A method for recording information on a recording medium utilizing an interference pattern by interference between an information light modulated spatially with digital pattern information displayed on a spatial light modulator having multiple pixels and a reference light for recording. In order to provide a novel recording method capable of enhancing the recording density and the transfer rate furthermore, digital information to be recorded is represented by match / mismatch of the attributes of adjacent pixels in the spatial light modulator to produce digital pattern information.
Owner:OPTWARE
Magnetic recording medium
ActiveUS8142916B2Magnetic materials for record carriersRecord information storageCrystal orientationOptoelectronics
Provided is a magnetic recording medium which maintains high S / N ratio and coercive force (Hc) and has high recording density, even with fine magnetic particles, by further improving crystal orientation of a magnetic recording layer. The magnetic recording medium is provided with an orientation control layer (16), a nonmagnetic under layer (18), and a magnetic recording layer (22) on a substrate. The orientation control layer (16) has an fcc structure and a (111) plane parallel to the substrate. The under layer (18) has an hcp structure and a (0001) plane parallel to the substrate. An atomic distance of the (111) plane of the orientation control layer (16) is −0.2 Å to +0.15 Å to a lattice spacing of the under layer (18).
Owner:WESTERN DIGITAL TECH INC
Evaluation method of perpendicular magnetic recording medium and manufacturing method of perpendicular magnetic recording medium
InactiveUS8665541B2Improve recording densityImprove productivityRecord information storageCarrier monitoringSignal-to-noise ratio (imaging)Engineering
Owner:WD MEDIA SINGAPORE PTE
Magnetic disk and manufacturing method thereof
ActiveUS20120127599A1Guaranteed uptimeImprove reliabilityDriving/moving recording headsProtective coatings for layersEnvironmental resistanceCompound a
A magnetic disk is provided which is excellent in durability of the magnetic disk or particularly in LUL durability and CFT characteristics and has high reliability under a decreased floating amount of the magnetic head accompanying the recent rapid increase in a recording density and extremely severe environmental resistance accompanying diversification of the applications.The magnetic disk of the present invention is a magnetic disk having at least a magnetic layer, a carbon protective layer, and a lubrication layer sequentially provided on a substrate, and the lubrication layer is a film formed by a lubricant that contains two types of compounds having a perfluoropolyether main chain in the structure, a molecular weight distribution of the two types in total being within a range of 1 to 1.2, the two types of compounds including a compound a having a hydroxyl group at the end and a compound b having a number average molecular weight smaller than the number average molecular weight of the compound a and not more than 1500, and a content of the compound b in the two types of compounds being not more than 10%.
Owner:WESTERN DIGITAL TECH INC
Magnetic disk and method of manufacturing the same
InactiveUS20100304186A1Maintain good propertiesImprove reliabilityProtective coatings for layersRecord information storagePerfluoropolyetherBackbone chain
Provided is a magnetic disk comprising a lubricating layer formed of a lubricant. The lubricant constituting the lubricating layer has excellent properties, for example, excellent fluidity, surface energy, and CFT properties. By virtue of the excellent properties, the magnetic disk has a high level of reliability despite a low flying height of a magnetic head due to a recent rapid increase in recording density and a very severe environment resistance requirement due to diversification of applications. The magnetic disk comprises a substrate and at least a magnetic layer, a protective layer, and a lubricating layer provided in that order over the substrate. The lubricating layer is formed of a lubricant that is a mixture of a specific perfluoropolyether lubricant with a lubricant formed of a compound comprising perfluoropolyether groups having a perfluoropolyether main chain in the structure thereof and having a hydroxyl group at the end thereof, the perfluoropolyether groups being bonded to each other through a divalent linking group having at least two hydroxyl groups in the structure thereof.
Owner:WESTERN DIGITAL TECH INC
Apparatus and method for the control and positioning of magnetic recording heads in an azimuth recording system
InactiveUS6088184AImprove recording densityImproved azimuthal recordingDriving/moving recording headsFilamentary/web record carriersMagnetic tapeRecording density
A magnetic recording apparatus and method for the azimuthal recording of data to and from data storage tracks contained on digital linear tape. The magnetic recording apparatus includes a magnetic data recording head assembly. A magnetic recording head is centrally located within the magnetic data recording head assembly. The magnetic data recording head assembly includes a control device coupled to a left servo sensor, wherein the left sensor is located to the left of and external to the magnetic recording head. The magnetic recording apparatus additionally includes a control device coupled to a right servo sensor, wherein the right servo sensor is located to the right of and external to the magnetic recording head. The left and right servo sensors assist the magnetic recording head to tilt and rotate at a predetermined angle with respect to a particular data storage track contained on a digital linear tape, during a recording operation, thereby increasing recording density and providing improved azimuthal recording.
Owner:IBM CORP
Novel process and structure to fabricate CPP spin valve heads for ultra-hing recording density
InactiveUS20050201022A1Enhanced Specular ReflectionIncrease bulk scatteringNanostructure applicationNanomagnetismDopantSpins
A CPP-GMR spin value sensor structure with an improved MR ratio and increased resistance is disclosed. All layers except certain pinned layers, copper spacers, and a Ta capping layer are oxygen doped by adding a partial O2 pressure to the Ar sputtering gas during deposition. Oxygen doped CoFe free and pinned layers are made slightly thicker to offset a small decrease in magnetic moment caused by the oxygen dopant. Incorporating oxygen in the MnPt AFM layer enhances the exchange bias strength. An insertion layer such as a nano-oxide layer is included in one or more of the free, pinned, and spacer layers to increase interfacial scattering. The thickness of all layers except the copper spacer may be increased to enhance bulk scattering. A CPP-GMR single or dual spin valve of the present invention has up to a threefold increase in resistance and a 2 to 3% increase in MR ratio.
Owner:HEADWAY TECH INC
Method of manufacturing a perpendicular magnetic recording medium
ActiveUS8298689B2Improve coercive forceImprove recording densityRecord information storageCoating by sputteringForming gasRecording layer
Owner:WESTERN DIGITAL TECH INC
Perpendicular magnetic recording medium
ActiveUS8057926B2Record information storageCoating part of support with magnetic layerRecording layerNon magnetic
Owner:WESTERN DIGITAL TECH INC
Perpendicular Magnetic Recording Media
ActiveUS20120140359A1Improve recording densityNarrow widthRecord information storageDisk carriersRecording layerRecording density
[Summary][Problem] An object is to provide a perpendicular magnetic recording medium in which a narrower track width is achieved by enhancing an exchange coupling magnetic field Hex of a soft magnetic layer so that a higher recording density can be achieved.[Solution] A perpendicular magnetic recording medium according to the present invention is configured to include a magnetic recording layer 122 that records a signal, and a soft magnetic layer 114 provided below the magnetic recording layer, on a base 110 on a main surface of which textures are formed, wherein the textures includes first textures 110a that is linear rails in a certain direction, and second textures 110b that are trails intersecting at a predetermined angle with the first textures; and the angle of intersection between the first textures and the second textures is 10° or less.
Owner:WESTERN DIGITAL TECH INC
Perpendicular Magnetic Recording Disc
ActiveUS20120141833A1Improve crystal orientationImprove signal-to-noise ratioMaterial nanotechnologyRecord information storageCrystal orientationAlloy
[Problem] A perpendicular magnetic disk with an improved SNR and an increased recording density by further improving crystal orientation of a preliminary ground layer formed of an Ni-base alloy is provided.[Solution] A typical structure of the perpendicular magnetic disk according to the present invention includes, on a base 110, a soft magnetic layer 130, a Ta alloy layer 140 provided on the soft magnetic layer 130, an Ni alloy layer 142 provided on the Ta alloy layer 140, a ground layer 150 provided on the Ni alloy layer 142 and having Ru as a main component, and a granular magnetic layer 160 provided on the ground layer 150. The Ta alloy layer 140 is a layer containing 10 atomic percent or more and 45 atomic percent or less Ta and having amorphous and soft magnetic properties.
Owner:WESTERN DIGITAL TECH INC
Lubricant compound for magnetic disk and magnetic disk
ActiveUS20120127601A1Reduction of magnetic spacingImprove reliabilityProtective coatings for layersMagnetic materials for record carriersEnvironmental resistanceRecording density
A lubricant compound for a magnetic disk is provided which can realize further reduction of the magnetic spacing and moreover, has high reliability under a lower floating amount of the magnetic head involved with the recent rapid increase in the recording density and under extremely severe environmental resistance involved with diversification of the applications.A lubricant compound is contained in a lubrication layer of a magnetic disk in which at least a magnetic layer, a protective layer, and a lubrication layer are sequentially provided on a substrate, and the lubricant compound contains a component A and a component B expressed by the following chemical formula:[Chemical formula]1 Component A: X=OHComponent B: X=OCH2CH(OH)CH2OHand a component C made of a specific compound having a phosphezene ring in the structure thereof.
Owner:WESTERN DIGITAL TECH INC
Method of producing a perpendicular magnetic recording medium
InactiveUS20110206947A1Improving sliding durabilityImprove reliabilityMagnetic materials for record carriersVacuum evaporation coatingAlloyRecording layer
By improving sliding durability while ensuring a high SNR, an improvement in reliability and a further increase in recording density are to be achieved.The structure of a method of manufacturing a perpendicular magnetic recording medium according to the present invention includes: a main recording layer forming step of forming, on a substrate, at least a main recording layer formed of magnetic particles having a CoCrPt alloy as a main component and a non-magnetic grain boundary part having an oxide as a main component; a split layer forming step of forming a split layer having a Ru alloy or a Co alloy as a main component on the main recording layer; a first heating step of performing a heat treatment on the substrate after the split layer forming step; an auxiliary recording layer forming step of forming an auxiliary recording layer formed of a material having CoCrPt as a main component after the first heating step; a second heating step of performing a heat treatment on the substrate after the auxiliary recording layer forming step; and a protective layer forming step of forming a protective layer having carbon as a main component by CVD after the second heating step.
Owner:WD MEDIA SINGAPORE PTE
Perpendicular magnetic recording medium and a method for manufacturing the same
ActiveUS20050153169A1Improves electromagnetic conversion characteristicImprove corrosion resistanceBase layers for recording layersVacuum evaporation coatingInter layerNon magnetic
A perpendicular magnetic recording medium has a magnetic recording layer and laminated magnetic layers composed of different materials. In a first magnetic layer of the magnetic recording layer, ferromagnetic grains are surrounded by a nonmagnetic grain boundary region composed principally of oxide and / or nitride. In a second magnetic layer of the magnetic recording layer, ferromagnetic grains are surrounded by a nonmagnetic grain boundary region composed principally of chromium. The recording medium has an intermediate layer composed of a material having hcp or fcc structure. Advantageously, a heating process is conducted after forming the first magnetic layer and before forming the second magnetic layer. The medium achieves improvement in electromagnetic conversion characteristics and simultaneously improvement in corrosion resistance to provide a perpendicular magnetic recording medium with high recording density and simultaneously high reliability.
Owner:FUJI ELECTRIC CO LTD
Electron beam irradiating method and manufacturing method of magnetic recording medium
The present invention is to make it possible to form a fine pattern, and improve a recording density on a magnetic recording medium and increase signal intensity. There is provided an electron beam irradiating method which irradiates an electron beam on a resist to perform irradiating using an electron beam irradiating apparatus provided with a moving mechanism which moves a state on which a substrate applied with the resist is put in one horizontal direction, and a rotating mechanism which rotates the stage. The electron beam irradiating method includes: exposing a portion once exposed while changing a deflection amount of the electron beam at least one time in the next round and rounds subsequent thereto, when exposure is performed while a deflection amount of an electron beam is being gradually changed so as to draw a concentric circle for each round.
Owner:KK TOSHIBA
Magnetic disk apparatus with heating device and magnetic head slider used therefor
InactiveUS20050213250A1Reduce power consumptionImprove recording densityRecord information storageFluid-dynamic spacing of headsRecording densityElectric power
Embodiments of the invention achieve a decrease in electric power consumption while ensuring high recording density and high reliability in a magnetic disk apparatus. In one embodiment, a magnetic disk apparatus comprises a rotatable magnetic disk and a magnetic head slider to be able to fly above a surface of the magnetic disk. The magnetic head slider comprises an air bearing surface, by which the magnetic head slider is caused to fly and come near to the rotating surface of the magnetic disk with a predetermined spacing therebetween, recording and reproducing elements to perform at least one of recording on and reproduction from the magnetic disk, and a heating device to adjust a distance between the recording and reproducing elements and the surface of the magnetic disk. The heating device is mounted such that heating thereof causes a part of the air bearing surface to expand and project to increase a distance between the recording and reproducing elements and the surface of the magnetic disk.
Owner:WESTERN DIGITAL TECH INC
Optical disk apparatus with flexible capacity by adjustment of recording density
InactiveUS20030021202A1Low densityQuality improvementRecord information storageDigital recordingRecording densityComputer science
A method is designed for recording contents information along a track of an optical disk of a writeable type. A volume detection step is carried out for detecting an actual volume of the contents information to be recorded into the optical disk. A capacity detection step is carried out for detecting a nominal capacity of the optical disk, which indicates a rated volume of information to be recorded at maximum. A density determination step is carried out for determining a recording density of the contents information based on the detected actual volume and the detected nominal capacity. A record step is carried out for recording the contents information into the optical disk at the determined recording density such that the actual volume of the contents information can fit into the nominal capacity of the optical disk.
Owner:YAMAHA CORP
Recording head and information recording apparatus
To generate a satisfactory recording magnetic domain on a recording medium and to improve the durability of a recording head, an information recording apparatus for generating an optical near field and thermo-magnetically recording information on the recording medium is provided with a light source, a magnetic pole for applying a magnetic field to the recording medium and a diffuser that generates an optical near field in the vicinity of the recording medium when light from the light source is radiated. The diffuser is formed with it in contact with the magnetic pole so that the face which light from the light source irradiates is substantially perpendicular to the recording medium. Thereby, recording density in the information recording apparatus can be increased, simultaneously the reliability can be also enhanced and as a result, the cost can be reduced.
Owner:HITACHI LTD
Class of fixed partial response targets in a PRML sampled data detection channel
InactiveUS6249398B1Modification of read/write signalsRecord information storageFrequency spectrumMagnetic media
A new class of fixed partial response targets are disclosed for use in a PRML magnetic medium read channel. The preferred embodiment exhibits an equalization response characterized by the polynomial 7+4*D-4*D2-5*D3-2*D4, where D represents the unit delay operator. This read channel target provides improved matching to the inherent magnetic channel over the known canonical class of targets (1-D)(1+D){circumflex over ( )}N, and thereby reduces equalization losses. The improved spectral matching reduces amplification of noise in the channel, thereby reducing bit-error-rates. The new class of targets also exhibits a spectral null at DC, reducing problems for offset cancellation circuitry and making the disk drive less sensitive to thermal asperities. It also exhibits a spectral depression rather than a spectral null at the Nyquist frequency, making quasi-catastrophic error sequences virtually impossible. The new class of target simplifies coding and allows RLL code ratios that approach unity, improving effective recording densities, while significantly reducing BER.
Owner:LUCENT TECH INC +1
Optical disk identification device
The present invention provides an optical disk identification device for use in an optical disk reproduction apparatus for reproducing a plurality of types of optical disks based on information recorded on the optical disks. Recorded information is reproduced from an optical disk 1 while an optical pickup 3 is fixed at a focal position Pf. A focal position detector 32 generates a focal position detection signal Sg that is either at a high level or at a low level at the focal position Pf based on reproduced signals Sa, Sb, Sc, Sd. An RF signal detector 20 detects an RF signal Srf from the reproduced signal based on the focal position detection signal Sg. A recording density identifier 31, S14, S20 identifies the recording density of the optical disk based on the RF signal. A format identifier S16 to S24 identifies the type of the optical disk based on the detected recording density.
Owner:PANASONIC CORP
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