Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Yuji Hata

Yoshio Soyama

Akio Shioya

Shigeyoshi Saito

Masahito Kobayashi

Tsuyoshi Takahashi

Takashi Yamaguchi

Kazuo Ono

Masahiko Sega

Takuji Ogawa

Shinsuke Nakagawa

Jyousei Shimizu

Yosuke Hamada

Haruaki Otsuki

Yukiyoshi Takamura

Katsumoto Onoyama

Tomohisa Ogasawara

Iwao Oshimi

Kiyotada Ito

Masaki Yoshioka

Kenichi Masuda

Takeshi Nakazawa

Takayuki Umemoto

Hiromoto Takeda

To provide a storage control device capable of changing the rotation speed of storage devices. A plurality of hard disk drivesis mounted in the device mounting unit. The rotation speed control unitdetects the mounting location of each hard disk drive, and determines the rotation speed in accordance with the location of each hard disk drive. The rotation speeds of adjacent hard disk drivesare different from each other. The rotation speed control unitchanges the rotation speed of each hard disk driveto the determined rotation speed.

Storage control device and rotation speed control method for storage device

When a head passes over a track with a projected item in a seek operation, the CPU delays a seek start time to conduct the seek by changing a period of time from a seek start position to a position of the track with a projected item. Or, the CPU conducts seek control by changing a speed table. Or, the CPU changes a sequence of items of a tag queue to obtain a seek locus not passing the projected item. By the control operation, a seek error due to thermal asperity is prevented and the head is not damaged. This also prevents appearance of a new projected item produced by contact between the magneto-resistive head and the projected item on the recording medium.

Disk device and seek control method

In a magnetic disk drive that performs the seek operation of a magnetic head by a VCM, a characteristic that is excellent in fault tolerance that will not generate a fault in severe environment, such as a high temperature and the issue of high frequency command without requiring a special device and special operation and without deteriorating access performance. For this purpose, a VCM current and a VCM voltage are measured and VCM back electromotive force is calculated based on both results. At seek operation, position information located on a magnetic disk is sampled and a traveling velocity is detected from the difference of the sampled result. VCM coil temperature is estimated from the difference between the traveling velocity and the VCM back electromotive force. The magnetic disk drive moves low velocity seek mode when the estimated value of this VCM coil temperature exceeded a specified value.

Magnetic disk drive and control method thereof

A positioning control method of a magnetic disc apparatus is provided which can permit fast and stable settling to a target position without overshoot or undershoot in connection with a moving distance of one track seek to about 16-track seek for which positioning must be determined within a moving time corresponding to a resonance frequency of a mechanical system. Such a method can also generate a position/velocity orbit for reducing power at a specified frequency, provide acceleration feed-forward compensation which can permit a head to accurately reach the target position even when the feedback system does not function under a condition that external disturbance does not act and generate a position orbit corrected by a controlled object model accurately modeling resonance oscillation up to a moving frequency band are used in combination.

Positioning control method

A disk apparatus has a position signal detector for detecting the position of a head with a specified sampling period, a controller operating a manipulated variable to control positioning of the head using a microprocessor and a digital/analogue converter with which the manipulated variable is converted. At least one or more timing registers set the timing of the conversion carried out by the D/A converter and at least one or more manipulated variable registers set a manipulated variable that is converted into digital/analogue form at the set timing. In addition, the controller has advancing means to make a target position trajectory advance towards a specified time, a feedforward controller to receive the output of the advancing means and to calculate a feedforward control variable on the basis of a target trajectory, and a feedback controller to produce a feedback output variable on the basis of a target trajectory that is delayed relative to a target position trajectory by a specified time.

Disk apparatus and method of controlling disk apparatus

When a magnetic recording and reproducing apparatus is in a waiting state, feedback control for positioning the carriage is released, and a supply of a sense current to the magnetoresistive effect element of the MR magnetic head is adjusted so as to prolong the life of the MR magnetic head. When the interface and control circuit recognizes that there is no order from the host computer and that the magnetic recording and reproducing apparatus is in a wait state, the servo control circuit releases the feedback control for positioning the head. A mode, etc. selection control circuit controls the recording/reproduction amplifier so as not to supply a sense current to the magnetoresistive effect element of the MR magnetic head. Accordingly, the time for supplying a sense current to the magnetoresistive effect element of the MR magnetic head is reduced in a great measure and, therefore, it is possible to prevent the deterioration of the element characteristics by electro-migration or the like. The result is that the life of the element can be prolonged. Hence, the output of the MR magnetic head can be increased without sacrificing the reliability. Accordingly, it has become possible to improve the performance of a high-output magnetic recording and reproducing apparatus using an MR magnetic head.

Method and apparatus for controlling magnetoresistive effect element head

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 method of recording a servo signal on each track of a magnetic disk includes a first signal for demagnetizing the magnetic disk and a second signal for forming the servo signal. The recording width (core width) of the magnetic head is made greater than the width of the track. Parts for recording signals and not recording signals are set in each track. The first and second signals are selected and recorded in the signal recording part, thereby to form the servo signal. Current to be conducted to the magnetic head is cut in the part for not recording signals, and the track is skipped to the next part for recording signals. When the recording of the track has ended, the magnetic head is moved to the next track, and the above steps are repeated.

Servo information recording method for a storage apparatus

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Odawara, Japan

Yuji Hata