Hitachi, Ltd.

Western Digital Technologies, Inc.

Renesas Technology Corp.

Hitachi Global Storage Technologies Netherlands B.v.

Hitachi Global Storage Technologies Japan, Ltd.

Other

Hitachi Video and Information System, Inc.

Akita Electronics Systems Co., Ltd.

Global Stone Material, Inc.

Hiroshi Ide

Takeshi Maeda

Takehiko Hamaguchi

Fumiyoshi Kirino

Atsushi Saito

Toshimitsu Kaku

Seiichi Mita

Kazuo Shigematsu

Tsuyoshi Toda

Hisashi Takano

Yasutaka Nishida

Yohji Maruyama

Hideki Sawaguchi

Hiroyuki Tsuchinaga

Futoshi Tomiyama

Fumio Kugiya

Atsushi Nakamura

Hiroyuki Hoshiya

Takashi Nara

Takushi Nishiya

Hisataka Sugiyama

Hirofumi Sukeda

Takatoshi Kato

Katsuro Watanabe

Terumi Takashi

Hideki Saga

Yoshiaki Kawato

Hiroaki Nemoto

Masahiko Takahashi

Satoshi Fujita

Yuko Tsuchiya

Kimio Nakamura

Yasushi Fukuda

Naoto Ito

Shintaro Suzumura

Hideyuki Yamakawa

Akira Morinaga

Masaomi Ikeda

Nobuaki Nakai

Nobukazu Doi

Yoshinori Okada

Hisashi Kimura

Kiyoshi Honda

Masaru Ito

Morishi Izumita

Tatsuya Hirai

Takehiko Umeyama

Yoshiju Watanabe

Yasuhide Ouchi

Hideki Zaitsu

Toshio Niihara

Satoshi Kawamura

Yoji Maruyama

Soichi Isono

Masahiko Hatatani

Hitoshi Komatsu

Yuji Yamane

Yoichi Uehara

Yasuo Inagaki

Hideo Tanabe

Norifumi Miyamoto

Kyoko Tsukano

Tsuyashi Toda

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to data segments of a first data track, and second data is written to data segments of a second data track. After writing the second data, the first data is read at multiple off-track offsets of the first data track to measure an average off-track read capability (OTRC) of the first data track. A cross-track profile is generated for a first data segment of the first data track, and at least part of the cross-track profile is correlated with the measured average OTRC.

Data storage device defining track trajectory to reduce AC track squeeze

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, wherein each data track comprises a plurality of data segments. First data is written to a first data segment of a first data track, and second data is written to a second data segment of a second data track. After writing the second data, a quality metric is measured for at least two off-track offsets of the first data segment. A track pitch is estimated between the first data segment and the second data segment based on the quality metrics, and a track trajectory is generated for the second data segment based on the estimated track pitch. Third data is written to the second data segment based on the track trajectory.

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks. A plurality of zones are defined for the disk, wherein each zone comprises a plurality of the data tracks. Position error signal (PES) repeatable runout (RRO) values are generated based on the servo data in a first zone, and data sector squeeze RRO values are generated based on data segments in the first zone. A first data track format for the first zone is generated based on the PES RRO values, and a second data track format is generated for the first zone based on the data sector squeeze RRO values.

Data storage device generating PES RRO and data sector squeeze RRO for a plurality of zones

Disclosed is a tile unit () that includes a resin net (), a plurality of tiles () disposed on a front side of the resin net, and a magnet sheet () disposed on a back side of the resin net, with the tiles being bonded and fixed to the magnet sheet with the resin net interposed therebetween.

Tile unit

There is provided a semiconductor device capable of supplying an analog input signal higher than or equal to an operating power supply voltage. An electrostatic discharge protection circuit corresponding to the analog input signal is provided for an external terminal that is supplied with an analog input signal generated with a first power supply voltage. A voltage divider resistor divides the analog input signal passing through the electrostatic discharge protection circuit into a voltage corresponding to a second power supply voltage lower that the first power supply voltage. An input circuit operating on the second power supply voltage receives the analog input signal divided by the voltage divider resistor to form an internal analog signal. There are provided first and second unidirectional elements. The first unidirectional element passes current from the input circuit's input terminal to the second power supply voltage. The second unidirectional element passes current from a circuit ground potential to a first circuit's input terminal.

Semiconductor device

An output of a magnetic head changes depending on the environmental temperature of a magnetic disk. In particular, under cold temperature conditions, an output of the head largely decreases mainly due to an increase in coercivity of a magnetic recording medium, which degrades an error rate. In one embodiment of the invention, sense-current optimization processing of a magnetic disk drive comprises the steps of: measuring the environmental temperature; and after a sense-current value which is set from the viewpoint of the reliability of the magnetic head is defined as an upper limit, finding out a sense current Is that can achieve the best error rate (BER) at the temperature. While changing a value of the sense current Is inside the magnetic disk drive, an error rate is measured. Then, a sense current Is_opt at which the best error rate properties are achieved is selected as a new set value.

Magnetic disk drive with control of sense current of magnetic head

In the present invention, by making the width of the write element larger than the track pitch and securing a write magnetic field strong enough to reverse the magnetization of the magnetic layer, and further by writing while shifting a write head comprising the write element, a magnetic disk drive, of which the track width is narrower than the write element width, and the storage capacity is large, is realized.

Magnetic disk drive

A write head's material having a great thermal expansion coefficient expands due to Joule heat resulting from a write current and a temperature rise dependent on high-frequency core loss, thereby causing the head's flying surface to protrude toward a magnetic disk. This phenomenon is called TPR (thermal protrusion). It is essential that the flying height be accurately determined and managed in consideration of TPR. A magnetic disk drive for actual use or a magnetic disk drive that is in a testing process but similar to the one for actual use is used to measure TPR amount changes resulting from a write operation, store the resulting measured data in a memory or on the magnetic disk, and perform flying height management with the stored measured data. Further, flying height management is performed as needed in conjunction with a SMART function. The present invention makes it possible to perform high-reliability flying height management.

Magnetic disk drive having a function for using a thermal protrusion amount for flying height management and an inspection device having such a function

A method of recording data into a recording medium by forming a recording region which is physically different from the nonrecorded portions is disclosed. The optical data recording/reproducing method includes a first trial writing operation in which trial writing data are recorded into the recording medium while changing the recording power conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set an optimum recording power. The method also includes a second trial writing operation in which trial writing data are recorded into the recording medium while changing the servo conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set optimum servo conditions.

Magneto-optical data recording/reproducing method

A disk type record playback device having a wobble signal extracting bandpass filter for controlling a filter's center frequency according to a frequency follow-up control loop including a dummy filter identical in configuration to a filter to be controlled, and a phase comparator is capable of controlling the center frequency of the bandpass filter with satisfactory accuracy. A frequency variable lowpass filter is provided in a preceding stage of the phase comparator constituting a frequency follow-up circuit and supplies a signal obtained by eliminating harmonic components from a frequency follow-up clock signal to the phase comparator. A cutoff frequency of the lowpass filter is changed in cooperation with a center frequency of the bandpass filter, based on a signal outputted from the frequency follow-up control loop.

Semiconductor integrated circuit and medium record playback device

Magnetic disk device having a write head to write by shifting in a radial direction

In order to generate a sampling clock having a higher accuracy, a synchronous signal generating circuit is provided with a phase error detector, detecting a phase error of a read out signal digitized on the basis of FDTS algorithm, and a VCO, controlling an oscillation frequency on the basis of a phase error detected by the phase error detector, to generate a synchronous signal by the VCO. On the basis of the synchronous signal generated by the synchronous signal generating circuit, an ADC digitizes the read out signal. The digitized read out signal is then converted to binary data by a detection circuit.

Apparatus for information recording and reproducing

To provide a spin-valve type magnetic head having high read output even if track width is narrow and high stability, a magnetic head according to the invention is provided with a spin-valve type magnetoresistive element in which a single magnetic domain turning ferromagnetic layer is formed on a soft magnetic free layer via a non-magnetic separating layer, the soft magnetic free layer and the single magnetic domain turning ferromagnetic layer are magnetostatically coupled at the end of track width, a closed magnetic circuit is formed and the soft magnetic layer has magnetization substantially induced in a direction substantially perpendicular to an external magnetic field.

Spin-valve head containing closed-flux-structure domain control films

Provided is a thin film single pole head for perpendicular magnetic recording, which has a structure offering a high formatted volume, easy servo, difficulty of influencing a recording pattern on a medium, and capability of shortening processing time. This thin film single pole head for perpendicular magnetic recording is formed on a reproducing head composed of a pair of shield layers formed on a substrate, and a reproducing element formed therebetween. A structure is provided, where an auxiliary pole is not disposed between the reproducing element of the reproducing head and the main pole of a recording head when seen from a surface facing to recording media.

Magnetic head and magnetic disk drive

Growing community of inventors

Kodaira, Japan

Hiroshi Ide