Fujitsu Corporation

Kabushiki Kaisha Toshiba

Toshiba Storage Device Corporation

Toshiba Electronic Devices & Storage Corporation

Fukitsu Limited

Kazuhiko Takaishi

Takeshi Hara

Tomoyoshi Yamada

Masanori Fukushi

Shinsuke Akiya

Kunihiro Shimada

Shunji Saito

Hiroyuki Suzuki

Takeyori Hara

Hideo Sado

Tatsuhiko Kosugi

Tsugito Maruyama

Masafumi Iwashiro

Susumu Hasegawa

Eiji Okamura

Hiroshi Oyabu

Takao Abe

Hiroshi Kubota

Takashi Matsumoto

Yoshifumi Mizoshita

Keiji Aruga

Shuichi Hashimoto

Hiroshi Tani

Sumio Kuroda

Eisaku Takahashi

Mitsuo Kamimura

Satoshi Yamashita

Yasumasa Kuroba

Norio Yagi

Kenichi Myokan

Yukihiro Uematsu

Takahisa Ueno

Susumi Hasegawa

Takehiko Katoh

According to one embodiment, a magnetic disk device writes a plurality of simulated reference patterns to the magnetic disk on write conditions different from each other, detects a write state of each of the simulated reference patterns, selects one of the write conditions according to detection results, and writes a plurality of regular reference patterns which become criteria for predetermined processing to be executed on the magnetic disk to the magnetic disk on the selected write condition.

Magnetic disk device and reference pattern writing method of the same preliminary class

A method for writing servo data includes: writing the servo data as the head moves outwardly towards a radial position on the disk one step at a time, wherein the same address data are written as the head moves outwardly in two consecutive steps, writing the servo data as the head moves inwardly towards the radial position one step at a time, so as to overwrite part of servo data that have been written in a previous step, wherein the same address data are written as the head moves inwardly in two consecutive steps, and writing either one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position.

Hard disk drive, manufacturing method of the same, and servo data writing method

A method for writing servo data includes writing servo data as a head moves outward on a disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, writing servo data as the head moves inward on the disk one step at a time, so as to overwrite part of servo data that have been written in a previous step, and writing one of two-phase burst data, or address data and the other of said two-phase burst data, at the radial position, so as to overwrite at least part of servo data written in each last step of the writings as the head moves outward and inward. The same address data are written in two consecutive steps as the head moves outward and as the head moves inward.

A method for manufacturing a disk device includes the steps of measuring a first gain of a control signal of a fine motion actuator while positioning a head to a first radial position of a disk medium using a coarse motion actuator but not the fine motion actuator, based on an auxiliary servo pattern recorded on the disk medium, measuring a second gain of a control signal of the fine motion actuator while positioning the head to a second radial position of the disk medium using the coarse motion actuator but not the fine motion actuator, based on the auxiliary servo pattern recorded on the disk medium, and determining gain correction values which are to be applied to a control signal for the fine motion actuator while performing servo pattern writing on the disk medium, based on the first and second gains.

Disk device and method for manufacturing disk device

According to one embodiment, a contact-detecting method includes calculating a representative value for each of a plurality of first zones. The plurality of first zones is provided at different radial locations on the disk. The representative value is calculated based on values measured at a plurality of different radial locations included in each of the first zones. The method includes detecting a contact point at which a first member contacts with a second member based on a first difference. The first difference is a difference between a value measured at an objective measuring point and a representative value of a second zone among the plurality of first zones. The objective measuring point is included in a third zone among the plurality of first zones. The second zone is arranged radially inward of the third zone.

Contact-detecting method, manufacturing method of disk drive, and disk drive

According to one embodiment, a magnetic disk device includes: magnetic heads; a magnetic disk in which servo patterns having different write frequencies from one another are divided and recorded into a plurality of zones; and a head controller configured such that, when performing seek control of the magnetic heads based on a model position and a model velocity obtained from a model which simulates the magnetic heads, the head controller corrects the model position and the model velocity, at the time of switching of the zones, so as to reflect variation of sampling time resulting from gaps between the zones.

Magnetic disk device and method of controlling magnetic heads

A magnetic disk device includes a magnetic disk on which servo information is recorded, a head to read the servo information of the magnetic disk, and a position control module. When carrying out positioning control of the head, the position control module estimates frequency components of noise in a head positioning control process, using a high-order digital filter that includes first and second variable coefficients that are each based on position error information generated from the servo information read by the head.

Magnetic disk device and head-position control method

According to one embodiment, a position demodulator includes a demodulator, a phase corrector, and a position demodulating module. The demodulator demodulates a first demodulated signal and a second demodulated signal having a phase difference of 90 degrees from the first demodulated signal as a result of discrete Fourier transform operation on a read signal of a null servo pattern recorded in a servo area of a medium read out by a head. The phase corrector carries out correction to tilt respective vectors of the first demodulated signal and the second demodulated signal represented on a phase plane by a predetermined angle. The position demodulating module demodulates a positional signal for determining the position of the core of the head based on the first demodulated signal and the second demodulated signal corrected by the phase corrector.

Position demodulator and position demodulation method

According to one embodiment, a position demodulation method includes demodulating a first demodulation signal and a second demodulation signal having a phase difference of 90 degrees to the first demodulation signal based on a read-out signal obtained by reading out a servo pattern recorded on a medium by the head for positioning of a head with respect to the medium; correcting the first and second demodulation signals in which, when a trace of a Lissajous figure is drawn representing the first and second demodulation signals as values on coordinate axes different from each other on a plane, a ratio of respective lengths between intersections of the trace intersecting with two axes orthogonal at an origin of the plane is kept constant; and demodulating a positional signal for determining a position of the head based on the first and second demodulation signals after being corrected at the correcting.

Position demodulation apparatus and position demodulation method

According to one embodiment, a disk storage device includes: a disk on which a servo pattern is recorded; a head; a driver; a signal generator; a demodulator; and a controller. Position signals for detecting an offset position from a center of a track are recorded in a recording area of a servo pattern. The signal generator generates a first timing signal indicating a timing for reading the position signals. When the controller performs a seek operation for moving the head to a target track, the signal generator generates a second timing signal. The period of the second timing signal for reading each of the position signals is made shorter than that of the first timing signal. A center time of the period of the second timing signal is shifted closer to a demodulation center time corresponding to a center of the recording area than that of the first timing signal.

Disk storage device, controller of the same, controlling method performed by the same, and electronic device

According to one embodiment, a disk storage device includes: a disk on which a servo pattern is recorded; a head; a driver; a signal generator; a demodulator; and a controller. Position signals for detecting an offset position from a center of a track are recorded in a recording area of a servo pattern. The signal generator generates a first timing signal indicating a timing for reading the position signals. When the controller performs positional control along a virtual circular orbit of the disk, the signal generator generates a second timing signal. The period of the second timing signal for reading each of the position signals is made shorter than that of the first timing signal. A center time of the period of the second timing signal is shifted closer to a demodulation center time corresponding to a center of the recording area than that of the first timing signal.

According to one embodiment, a position control apparatus includes: a digital control module that performs position control including disturbance adaptive control with a predetermined sampling period with the use of a control constant, in accordance with a position error between a target position and a current position of the object; and a table that stores the control constant corresponding to a value of sin(&#x3c9;T/2), wherein the digital control module determines a control value of the actuator in accordance with the position error, calculates the value of sin(&#x3c9;T/2) according to an adaptive law from a signal based on the position error, reads the corresponding control constant from the table in accordance with the calculated value of sin(&#x3c9;T/2), and updates the control constant.

Position control apparatus and disk apparatus using the same

According to one embodiment, a position control apparatus includes: a digital control module that performs position control including disturbance adaptive control with a predetermined sampling period using a control constant, in accordance with a position error between a target position and a current position of the object; and a table that stores the control constant corresponding to a value of sin(&#x3c9;T) or cos(&#x3c9;T), wherein the digital control module is configured to determine a control value of the actuator in accordance with the position error, calculates the value of sin(&#x3c9;T) or cos(&#x3c9;T) according to an adaptive law from a signal based on the position error, reads the corresponding control constant from the table in accordance with the calculated value of sin(&#x3c9;T) or cos(&#x3c9;T), and updates the control constant, to perform the position control including the disturbance adaptive control.

According to one embodiment, an information storage device includes a recording/reproducing head, a positioning controller, a position detector, a storage module, and a position error detector. The position detector detects the position of the recording/reproducing head. The storage module stores servo control filters. The position error detector generates a new position error signal from a target position and the position of the recording/reproducing head when the positioning controller performs positioning control with control current obtained from a position error signal having passed through each servo control filter. Upon occurrence of a recording/reproducing error, learning to calculate a vibration amount from the position of the recording/reproducing head is sequentially performed for the servo control filters for a predetermined time. The positioning controller performs the positioning control with control current obtained from the position error signal having passed through one of the servo control filters where the vibration amount is smallest.

Information storage device and computer product

According to one embodiment, a position control apparatus includes: a digital control module that performs position control including disturbance adaptive control with a predetermined sampling period using a control constant, in accordance with a position error; and a table that stores the control constant corresponding to one of values sin(&#x3c9;T), cos(&#x3c9;T), and sin(&#x3c9;T/2), wherein the digital control module determines a control value of the actuator in accordance with the position error, calculates a value of one of estimated errors of sin(&#x3c9;T), cos(&#x3c9;T), and sin(&#x3c9;T/2) according to an adaptive law from a signal based on the position error, multiplies the calculated estimated error by an adaptive gain in accordance with a value of the angular frequency &#x3c9;, updates one of the values, reads the corresponding control constant from the table based on the updated value, and updates the control constant.

Growing community of inventors

Kawasaki, Japan

Kazuhiko Takaishi