Abstract: Embodiments of the invention provide a magnetic disk drive having improved vibration characteristics and a reduced size. In one embodiment, a magnetic disk drive comprises: a motor shaft for rotating a magnetic disk; a sleeve for rotatably supporting the motor shaft; and a motor hub into which the motor shaft is press fit. The motor hub supports the magnetic disk and includes a projection portion having an inner surface and an outer surface. The inner surface is in contact with the press-fit motor shaft in directions perpendicular to the rotational axis of the motor shaft. The outer surface faces the sleeve.

Abstract: Methods to pattern substrates with dense periodic nanostructures that combine top-down lithographic tools and self-assembling block copolymer materials are provided. According to various embodiments, the methods involve chemically patterning a substrate, depositing a block copolymer film on the chemically patterned imaging layer, and allowing the block copolymer to self-assemble in the presence of the chemically patterned substrate, thereby producing a pattern in the block copolymer film that is improved over the substrate pattern in terms feature size, shape, and uniformity, as well as regular spacing between arrays of features and between the features within each array compared to the substrate pattern. In certain embodiments, the density and total number of pattern features in the block copolymer film is also increased. High density and quality nanoimprint templates and other nanopatterned structures are also provided.

Abstract: Methods and systems of enhancing stepper alignment signals and metrology alignment target signals. In one embodiment, a plurality of alternating rows comprising a first material of a first height and a second material of a second height are constructed. The first material and the second material are selected to enhance the contrast of the mark when imaged for alignment of photolithographic structures.

Abstract: Embodiments of the present invention help to improve the cost, mountability, and reliability of a magnetic disk drive that regulates a fly height of a magnetic head slider correspondingly to the operating altitude of the drive by using an air pressure sensor and a heater. According to one embodiment, a preamplifier is a semiconductor chip formed by three-dimensionally laminating thin film circuits on a bulk silicon wafer. An air pressure sensor is integrally formed on the semiconductor chip through a semiconductor process. The air pressure sensor is configured to include an isolating cavity, a diaphragm that deflecting in response to a change in a pressure difference between the isolating cavity and the outside, and lower and upper electrodes and for detecting variation in electrostatic capacitance. The preamplifier including the air pressure sensor integrally formed therein is attached to a flexible printed cable (FPC) to oppose the FPC.

Abstract: Embodiments of the present invention provide a method of producing a magnetic disk device in which a plurality of heads can appropriately record servo data on a magnetic disk. The method of producing the magnetic disk device according to one embodiment includes the steps of: attaching a magnetic disk, a plurality of heads and head amplifier circuit to the magnetic disk device; and recording the servo data input through the head amplifier circuit with the plurality of heads on the magnetic disk all at once; wherein the head amplifier circuit includes a plurality of amplifiers provided corresponding to the plurality of heads respectively and a plurality of registers which is provided corresponding to the plurality of amplifiers respectively and holds set values determining the amplification of the amplifiers, and the step of recording the servo data is conducted with the plurality of registers included in the head amplifier circuit individually set.

Abstract: Embodiments of the present invention provide a data recording device that allows swift data access even under the state that data access is difficult, and a control method for the device. According to one embodiment, when receiving a data reading command from an external host in the state that a reading-difficult state is being detected, a Microprocessing Unit/Hard Disk Controller (MPU/HDC) of a magnetic disk device reads data related to the reading command from a magnetic disk for transmission to an external host and recording into a memory. Thereafter, when receiving another reading command from the external host for the same data, the data is read from the memory for transmission to the external host.

Abstract: Embodiments of the present invention provide a data recording device capable of achieving desired performance while increasing the convergence rate. According to one embodiment, in a data recording device, an update-width determination unit included in a setting updating unit determines an update-width of a set frequency ƒ in a digital filter according to the size of a position error signal PES, and an update-width adjuster included in the setting updating unit changes the update-width of the set frequency ƒ determined by the update-width determination unit according to the size of the set frequency ƒ. Thus, while the convergence rate being kept properly, the set frequency ƒ can precisely be converged on a frequency of a disturbance component.

Abstract: Embodiments of the present invention help to prevent destabilization in voice coil motor (VCM) velocity control. According to one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) calibrates a correction operational coefficient of a detected back electromotive force (EMF) voltage before unloading. The calibration is carried out in a state that an actuator is pivoting. The HDC/MPU calibrates the correction coefficient according to a motion equation of the actuator using VCM current applied to a VCM and a detected value of a back EMF voltage detection circuit.

Abstract: Embodiments in accordance with the present invention help to obtain a perpendicular magnetic recording medium having a granular structure, excellent recording/reproducing properties, and excellent durability. According to one embodiment, a recording layer includes a layer which has crystal grains mainly composed of cobalt and crystal grain boundaries mainly composed of the oxide; the oxygen content of the recoding layer is changed in the film thickness direction; the oxygen content in the area in the vicinity of the interface between the recording layer and the intermediate layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer; and the oxygen content in the area in the vicinity of the interface between the recording layer and the protective layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer.

Abstract: Fluctuation of read/write characteristics during mass production is suppressed for a perpendicular magnetic recording medium having a perpendicular recording layer of a bi-layered structure, in which a first Co—Cr—Pt alloy magnetic layer containing an oxide and a second Co—Cr—Pt magnetic layer are formed successively. According to one embodiment, in a perpendicular magnetic recording medium, an adhesion layer, a soft magnetic underlayer, a seed layer, an intermediate layer, a perpendicular recording layer, a protective layer, and a lubricating layer are successively formed on a substrate. The perpendicular recording layer has a bi-layered structure in which a first Co—Cr—Pt alloy magnetic layer containing an oxide and a second Co—Cr—Pt alloy magnetic layer containing a marker element for measurement of a thickness selected from Mo, Mn, and V are successively formed, and the content of the marker element for measurement of thickness is about 1.5 at % or more and about 5 at % or less.

Abstract: Embodiments of present invention help to realize a highly reliable magnetic disk drive by preventing a positional displacement between a magnetic head and a target track by decreasing restricting forces that a cover exerts on a base when the temperature is increased. According to one embodiment, a base is formed by aluminum die casting, has a concave, rectangular parallelepiped shape, and is formed with step portions at the four corners. A cover is a flat plate of stainless steel or iron. Four corner portions of the cover are bent to form step portions. The cover is fixed to the base at the four corners with bolts at two side positions (six positions in total). A gasket is inserted at that time to enhance the sealing performance.

Abstract: Embodiments in accordance with the present invention provide a magnetic disk drive with reduced noise during seek operation without causing any delay in control response. According to one embodiment of the present invention, a control circuit of a magnetic disk drive controls the drive power supplied to a voice coil motor during a seek operation adapted to move a magnetic head over a target track formed on a magnetic disk so as to bring the travel speed of the magnetic head close to a predetermined target speed. The control circuit determines a provisional current according to the difference between the predetermined target speed and an actual travel speed in an acceleration zone adapted to accelerate the magnetic head to the predetermined target speed. If the provisional current exceeds a limit specified in relation to an elapsed time from the start of acceleration, the control circuit sets the limit as the current of the drive power supplied to the voice coil motor to control the motor.

Abstract: Embodiments in accordance with the present invention provide a sensor to produce high output with a small track width. Particular embodiments include forming a magnetoresistive sensor of a read head to be substantially vertical in its upper portion and gently upwardly convexly curved in its lower portion.

Abstract: Embodiments in accordance with the present invention control pitch variations that are not observed in self servo write (SSW). According to one embodiment of the present invention, an outer radius side area of a magnetic disk is erased using an external magnetic field, and an inner radius side area is subjected to self erase using a head. The magnetization state in the base of the inner radius side area is different from that of the outer radius side area before pattern writing. Therefore, in the inner radius side area and the outer radius side area, even if a radial pattern of the same pitch is read, the different APCs are measured. With SSW of this embodiment, a reference APC used in the inner radius side area is different from that used in the outer radius side area. In this manner, the pitch variation is prevented.

Abstract: Embodiments in accordance with the present invention provide a disk drive that ensures quieter rotational acceleration of a recording disk. Certain embodiments relate to a hard disk drive that detects the vibration of an enclosure by monitoring, via a driver, a counter electromotive voltage generated in a voice coil motor. If the hard disk drive detects a predetermined level of vibration or higher in the enclosure, it switches the status of a drive signal applied to a spindle motor so as to reduce the current level or smooth the waveform. This ensures reduced vibration of the enclosure.

Abstract: Embodiments in accordance with the present invention ensure that the pitch of a servo write track is accurately controlled. According to one embodiment of the present invention, a Self Servo Write (SSW) uses different methods and sequences to identify read-write offsets (RWOs) and calculate target positions in inner and outer diameter sides of a magnetic disk. In the inner diameter-side area, the SSW controller uses the readout of a radial pattern written on a recording surface and a reference value to identify the RWO. The SSW controller uses the RWO value identified in the inner diameter-side area to anticipate an RWO value in the outer diameter-side area. In the outer diameter-side area, the SSW controller uses the anticipated RWO value to determine the target position of each servo write track.

Abstract: A method and apparatus for providing a free layer having higher saturation field capability and optimum sensitivity (dr/R) is disclosed. The present invention provides a synthetic free layer that includes a first and second free layer, wherein the second free layer is a cobalt alloy that provides higher saturation and optimum sensitivity.

Abstract: A disk storage system having servo data stored thereon for accurate head position control over a magnetic or other storage medium. The servo data is seamless and untrimmed and consists of a primary servo burst set (AB burst) that defines the desired tract pitch for the surface. Multiple secondary servo burst sets (e.g., CD burst and EF burst) are written at the desired track pitch but radially offset from the primary burst set. The servo data is written in multiple servo sectors around the surface of the medium. From the servo data, PES (position error signals) are generated for providing linear position sensitivity information to the head position control logic. The resulting PES is more linear for smaller head sizes.

Abstract: A system and method are provided for manufacturing a coil structure for a magnetic head. Initially, an insulating layer is deposited with a photoresist layer deposited on the insulating layer. Moreover, a silicon dielectric layer is deposited on the photoresist layer as a hard mask. The silicon dielectric layer is then masked. A plurality of channels is subsequently formed in the silicon dielectric layer using reactive ion etching (i.e. CF4/CHF3). The silicon dielectric layer is then used as a hard mask to transfer the channel pattern in the photoresist layer using reactive ion etching with, for example, H2/N2/CH3F/C2H4 reducing chemistry. To obtain an optimal channel profile with the desired high aspect ratio, channel formation includes a first segment defining a first angle and a second segment defining a second angle. Thereafter, a conductive seed layer is deposited in the channels and the channels are filled with a conductive material to define a coil structure.

Abstract: A magnetic head system, and method for manufacturing a magnetic head are provided. Included is at least one layer and a heating element positioned adjacent the at least one layer. The at least one layer includes a plurality of sub-layers for providing an optimal thermal barrier.