Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Yosuke Hamada

Katsumoto Onoyama

Masahito Kobayashi

Takashi Yamaguchi

Katsuhiro Tsuneta

Hidehiko Numasato

Yoshikatsu Fujii

Tsuyoshi Arai

Jiro Abe

Iwao Oshimi

Atsushi Saito

Katsuro Watanabe

Yoshihiro Shiroishi

Mikio Suzuki

Takehiko Hamaguchi

Kenji Mori

Kyo Akagi

Takashi Kawabe

Masuo Umemoto

Kouichirou Wakabayashi

Kiyoshi Matsumoto

Hiromu Hirai

Isao Kobayashi

Reijiro Tsuchiya

Shinsuke Nakagawa

Yuji Hata

Haruaki Otsuki

Kiyotada Itou

Kiyotada Ito

Shigeyoshi Saito

Kazuyuki Date

In a disk device in which heads are positioned by a servo mechanism, the object of the present invention is to prevent data from being destroyed by incorrect selection of a head and to improve reliability in recording or reproducing information and to prevent format efficiency from being decreased thereby. For this object, a SAM pattern in a servo information region is changed for each head and recorded. Then, the SAM pattern is read to determine which head makes access to a disk surface and the head is compared with a head to which a direction of making access is given thereby to make an error check. Moreover, by the use of a marker pattern of rotational synchronization compensating data added to the servo information, an error check of the head making access to the disc surface is conducted.

Disk device having a function to confirm that a selected head is proper for a disk surface

A disk drive comprises a controller () that calculates a drive signal for positioning a head at a desired track on the basis of a desired track-position signal and a measured head-position signal, and a drive circuit for driving a voice-coil motor. The drive circuit includes a current feedback amplifier () and a voltage feedback amplifier (), which can be selectively used. The controller () is provided with a speed limiter for determining a maximum speed limiting the speed of a head. The voltage feedback amplifier of the drive circuit is used when the head-position signal is unstable or otherwise malfunctioning, and the current feedback amplifier of the drive circuit is used when the head-position signal is normal.

Disk storage device

A magnetic disk drive that drives and positions an actuator using a voice coil motor, includes a current sensing resistor connected in series to a terminal on current input side of the voice coil motor, a first operational amplifier and a second operational amplifier. The magnetic disk drive further includes one of a third operational amplifier and a microcomputer.

Magnetic disk drive and voice coil motor drive circuit

Settling response characteristics after change-over from a speed controller to a position controller is attained. Fluctuations in a time taken until change-over is made from the speed controller to the position controller are reduced to stabilize a moving time and to shorten an access time. To this end, a position controller generates a drive signal of a linear or primary function of time in such a manner that a position deviation signal responds to it with a ternary-order function of time which becomes zero in a desired finite settling time. Further, a feedforward signal generator is provided to reduce a follow-up error to a target position signal as an output of a target position signal generator. Furthermore, a switching judger is provided to start its judging operation after the position deviation signal reaches a predetermine position deviation and to perform switching operation from the speed controller to the position controller when the position deviation signal is not larger than a value corresponding to a proportional multiple of a speed signal.

Disk storage device and head positioning method

A magnetic disk drive uses a back electromotive force sensor that detects the back electromotive force produced in a VCM actuator without being affected by fast changes of current during a high-speed control sampling cycle, and that enables configuration of a fast, high-band speed control system. A back electromotive force sensor for disk drives has a first circuit that detests the coil terminal voltage of a voice coil motor and outputs that value as a band limited signal that is a constant multiple-of that value, a second circuit that detects a drive current in the voice coil motor and outputs a voltage signal proportional to that drive current, and a computation circuit that takes the difference between the output of said first circuit and the output of said second circuit.

A sector servo type magnetic disk apparatus is provided with, in addition to servo signals, a sensor such as an accelerometer for detecting a state of a magnetic head or a support for the magnetic head at a period shorter than a sampling period of the servo signals. Since an accelerometer mounted on the magnetic head or the support for the magnetic head detects an acceleration, the control performance of a servo control system can be improved, such as reduction of generation of mechanism resonance vibrations of a carriage and improvement on detection precision of a speed signal.

Magnetic disk apparatus having an accelerometer for detecting acceleration in the positioning direction of the magnetic head

Magnetic recorder and magnetooptical recorder

An apparatus for positioning a magnetic head includes a servo signal detection circuit for detecting a servo signal recorded on a magnetic disk in a predetermined first period, an acceleration measuring portion which is fitted to a part of a mechanism for mounting a magnetic head, outputs an acceleration signal in a direction of positioning the magnetic head, and samples the acceleration signal in a second period shorter than the first period, a comparison processing portion for comparing a deviation value computed from at least either one of the acceleration signal and the servo signal with a predetermined value, a write inhibit signal generating portion for generating a signal inhibiting write of data on a magnetic disk in accordance with the result of comparison in the comparison processing portion, and a manipulated variable compensation portion for generating manipulated variable for adjusting the position of the magnetic head from at least either one of the servo signal and the acceleration signal and a target value of the position of the magnetic head, whereby to prevent erroneous write operation of data onto a magnetic disk due to unsteady positioning error of the magnetic head.

Apparatus for positioning magnetic head and method of the same

A disk storage device comprises a microcomputer for estimating an external disturbance compensation signal and storing it and a first adder for adding the external disturbance compensation signal as a feedforward signal to a positioning compensation signal to a drive circuit. Where a positioning compensator for estimating a velocity signal based on a drive signal is provided, a difference signal between the drive signal and a signal proportional to the external disturbance compensation signal, instead of the drive signal, is applied to velocity estimation unit for correction.

Method and apparatus for eliminating external disturbances in a disk

A sample moving apparatus for positioning wafers with high accuracy, which apparatus comprises a fine adjustment actuator having a drive stroke to finely move the wafer, a fine adjustment stage driven by the fine adjustment actuator, a coarse adjustment actuator having a drive stroke to relatively coarsely move the wafer, a coarse adjustment stage driven by the coarse adjustment actuator, and a holder arrangement for attractively holding the wafer onto the wafer bearing surfaces of the respective stages. Upon selective energization of the holder arrangement of the respective stages, the wafer is moved while being attracted to the coarse adjustment stage or while being attracted to the coarse adjustment stage.

Sample moving apparatus, sample moving system and semiconductor

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Odawara, Japan

Yosuke Hamada