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Akihiko Takeo

Akihiko Takeo, Tachikawa-Shi JP

Patent application numberDescriptionPublished
20080297936METHOD AND APPARATUS FOR CORRECTING DATA ERRORS IN A DISK DRIVE - According to one embodiment, a disk drive that effectively corrects data errors, which are changes in the total number of data bits at the time of reproducing the data. The disk drive has a disk and a disk controller. The disk has a data-recording area constituted by a set of magnetic dots that are physically separated from one another. The disk controller uses error-correcting codes, determining an error that shows a change in the total number of bits in a data-bit string of the data set reproduced.12-04-2008
20090059417APPARATUS FOR ASSISTING WRITE OPERATION USING HIGH FREQUENCY MAGNETIC FIELD IN DISK DRIVE - According to one embodiment, a disk drive having a spin torque oscillator and designed to perform high frequency assisted writing. The disk drive has a magnetic disk, a magnetic head, a coil, and a drive current controller. The drive current controller controls a drive current to supply to the spin torque oscillator. To record data magnetically in the disk, the drive current controller supplies to the spin torque oscillator the drive current that changes in synchronism with the polarity inversion of the recording current supplied to the coil, which excites the recording magnetic pole of the magnetic head.03-05-2009
20090059418MAGNETIC HEAD AND DISK DRIVE WITH HIGH-FREQUENCY ASSISTED WRITING - According to one embodiment, a magnetic head having a head slider which holds a magnetic head unit including a heat-generating element for controlling the flying-height and a high-frequency oscillator for performing high-frequency assisted writing, and on which terminals connected to the magnetic head elements are used in the smallest number required. Terminals are mounted on the head slider and are connected to the magnetic head unit. The terminals include at least one current-supplying terminal that is connected to the heat-generating element serving to control the flying height and to the high-frequency oscillator.03-05-2009
20100232053METHOD AND APPARATUS FOR CONTROLLING HEAD WITH SPIN-TORQUE OSCILLATOR IN A DISK DRIVE - According to one embodiment, a disk drive has a magnetic disk and a magnetic head having a spin-torque oscillator. The disk drive further has a head amplifier IC configured to supply a write signal and a drive signal to the magnetic head. The write signal corresponds to write data. The drive signal is supplied to generate a high-frequency magnetic field. The head amplifier IC continuously supplies a drive signal of normal level to the spin-torque oscillator, and supplies a drive signal of high level higher than the normal level, only for a prescribed time after the polarity inversion of the write signal.09-16-2010

Patent applications by Akihiko Takeo, Tachikawa-Shi JP

Akihiko Takeo, Tokyo JP

Patent application numberDescriptionPublished
20090147401MAGNETIC RECORDING MEDIUM, METHOD OF MANUFACTURING THE SAME, AND MAGNETIC RECORDING/REPRODUCING APPARATUS - The present invention provides a magnetic recording medium capable of recording or reproducing high-density information by reducing the grain size of a perpendicular magnetic recording layer and improving vertical orientation, a method of manufacturing the same, and a magnetic recording/reproducing apparatus. The perpendicular magnetic recording medium includes: a non-magnetic substrate; and at least an soft magnetic layer, an under layer, an intermediate layer, and a perpendicular magnetic recording film that are formed on the non-magnetic substrate. At least one layer of the intermediate layer is made of an alloy material of an element having an fcc structure and an element having a bcc structure or an hcp structure, and has both a crystal structure having (111) orientation and an irregular layer lattice (stacking fault) caused by a mixture of the fcc structure and the bcc structure. The at least one layer of the intermediate layer is made of an alloy material of at least one element that is selected from a group composed of Pt, Ir, Pd, Au, Ni, and Co, which is a main ingredient, and has the fcc structure, and an element having the bcc structure or the hcp structure.06-11-2009
20100033873MAGNETIC RECORDING MEDIUM, METHOD OF MANUFACTURING MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING REPRODUCING APPARATUS - In a perpendicular magnetic recording medium in which at least a soft magnetic underlayer, an orientation control layer, a magnetic recording layer and a protective layer are formed on a non-magnetic substrate in order from the bottom, the orientation control layer has a laminated structure of two or more layers including an intermediate layer and a seed layer which is disposed closer to the non-magnetic substrate than the intermediate layer. The seed layer includes two or more kinds of elements having a face-centered cubic structure, has face-centered cubic (111) plane crystals oriented in a direction perpendicular to a substrate surface, and has a pseudo-hexagonal structure.02-11-2010
20100039730MAGNETIC RECORDING MEDIUM, METHOD OF MANUFACTURING THE SAME, AND MAGNETIC RECORDING/REPRODUCING APPARATUS - The present invention provides a magnetic recording medium which is capable of improving the perpendicular orientation of a perpendicular magnetic recording layer while maintaining a writing performance during recording and obtaining both an improvement in the perpendicular orientation and fine magnetic crystal particles with a uniform diameter, and which enables information to be recorded or reproduced at high density, a method of manufacturing the same, and a magnetic recording/reproducing apparatus. A magnetic recording medium 02-18-2010
20100188772METHOD FOR MANUFACTURING MAGNETIC RECORDING MEDIUM, MAGNETIC RECORDING MEDIUM, AND MAGNETIC RECORDING AND REPRODUCING APPARATUS - There are provided a method for manufacturing a magnetic recording medium which is excellent in terms of both the recording and reproduction characteristics and the thermal fluctuation characteristics without reducing the density and hardness of the perpendicular magnetic layer; a magnetic recording medium; and a magnetic recording and reproducing apparatus with which an excellent recording density is achieved,07-29-2010
20110205667MAGNETIC RECORDING HEAD AND MAGNETIC RECORDING/REPRODUCING APPARATUS USING THE SAME - A magnetic recording head includes a magnetic pole, a spin torque oscillator, a first shield and a second shield. The magnetic pole has an air-bearing surface. The spin torque oscillator is provided so that a first side of the spin torque oscillator faces the magnetic pole in a first direction parallel to the air-bearing surface. The first shield includes a granular magnetic material, and is provided so that two portions of the first shield sandwich the spin torque oscillator in a second direction which is parallel to the air-bearing surface and perpendicular to the first direction. The second shield is provided on a second side of the spin torque oscillator opposite to the first side.08-25-2011

Patent applications by Akihiko Takeo, Tokyo JP

Akihiko Takeo, Kawasaki-Shi JP

Patent application numberDescriptionPublished
20100165510VERTICAL MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING REPRODUCING APPARATUS - A magnetic recording medium comprising a substrate, at least one soft magnetic underlayer formed on the substrate, a perpendicular magnetic recording layer formed on the soft magnetic underlayer, and a protective layer formed on the perpendicular magnetic recording layer, is provided wherein the perpendicular magnetic recording layer is comprised of a primary recording layer, a non-magnetic intermediate layer and an auxiliary layer; the primary recording layer comprises magnetic crystal grains and grain boundary portions surrounding the magnetic crystal grains, and has a perpendicular magnetic anisotropy; the auxiliary layer has a negative magneto crystalline anisotropy; and the non-magnetic intermediate layer is formed between the primary recording layer and the auxiliary layer and comprises at least one metal selected from Ru, Rh and Ir, or at least one alloy thereof. This magnetic recording medium exhibits high heat resistance and good recording/reproducing characteristics, and enables a high recording density.07-01-2010
20100173175MAGNETIC RECORDING MEDIUM, PROCESS FOR PRODUCING SAME, AND MAGNETIC RECORDING REPRODUCING APPARATUS - A magnetic recording medium is provided, which has at least one soft magnetic layer, at least one seed layer, at least one underlayer and at least one perpendicular magnetic recording layer, and is characterized in that the or each seed layer is comprised of a covalently bonded material. The covalently bonded material preferably predominantly comprises a nitride having a hexagonal crystal structure, more preferably, predominantly comprises aluminum nitride having a hexagonal wurtzite crystal structure. This magnetic recording medium is superior in recording and reproducing an information with high density.07-08-2010

Akihiko Takeo, Minato-Ku JP

Patent application numberDescriptionPublished
20110151280PERPENDICULAR MAGNETIC RECORDING MEDIUM, METHOD FOR PRODUCING THE SAME, AND MAGNETIC RECORDING/REPRODUCING DEVICE - A perpendicular magnetic recording medium including at least a soft under layer, an orientation control layer, a magnetic recording layer and a protective layer on a non-magnetic substrate, wherein the orientation control layer is composed of three or more layers including a seed layer, a first intermediate layer and a second intermediate layer sequentially, formed in that order from the substrate side, the crystal grains that constitute the first intermediate layer are epitaxially grown on the crystal grains of the seed layer, the crystal grains that constitute the second intermediate layer are epitaxially grown on the crystal grains of the first intermediate layer, and the crystal grains that constitute the second intermediate layer are finer than the crystal grains that constitute the first intermediate layer.06-23-2011

Akihiko Takeo, Kunitachi-Shi JP

Patent application numberDescriptionPublished
20110261478MAGNETORESISTIVE ELEMENT AND MAGNETIC RECORDING APPARATUS - According to one embodiment, a magnetoresistive element includes a stack and a pair of electrodes that allows electric current to flow through the stack in a direction perpendicular to a surface of the stack. The stack includes a cap layer, a magnetization pinned layer, a magnetization free layer provided between the cap layer and the magnetization pinned layer, a tunneling insulator provided between the magnetization pinned layer and the magnetization free layer, and a functional layer provided within the magnetization pinned layer, between the magnetization pinned layer and the tunneling insulator, between the tunneling insulator and the magnetization free layer, within the magnetization free layer, or between the magnetization free layer and the cap layer. The functional layer includes an oxide including at least one element selected from Zn, In, Sn and Cd and at least one element selected from Fe, Co and Ni.10-27-2011