Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Atsushi Okuyama

Masahito Kobayashi

Hidehiko Numasato

Masato Soma

Shinya Imura

Shigeo Nakamura

Motoyasu Tsunoda

Kyo Akagi

Takashi Yoshida

Takashi Yamaguchi

Hitoshi Ogawa

Fujio Tajima

Masaki Odai

Norihisa Yanagihara

Minoru Makita

Kouji Katou

Masamichi Ito

Seiichi Domyo

Kazuaki Usui

Hideki Terauchi

Kenji Tamura

Kisasu Kaneko

Masayuki Iwasaki

Hidehito Yamada

Yasuhiro Mii

Toyomitsu Wakui

An information recording/reproducing system in which a host system making access to a magnetic disk apparatus can be limited to a specific one. A magnetic disk apparatus includes an authentication key generating block for generating an authentication key on the basis of physical characteristic(s) of the magnetic disk apparatus itself. The magnetic disk apparatus and the host system have, respectively, authentication key recording block for recording the authentication key and authentication data generating block for generating authentication data on the basis of the authentication key. Access from the host system to information of the magnetic disk apparatus is controlled based on the authentication data of the host system and the authentication data of the magnetic disk apparatus.

System for controlling host access to a storage device based on physical characteristics of the storage device

In a positioning control device for a two-stage actuator having a coarse-movement actuator and a fine-movement actuator, a notch filter having a cutoff frequency fn is provided to a coarse-movement control loop, and the fine-movement actuator is driven by a sine wave of the frequency fn. At the frequency fn, a head position signal becomes identical with an output signal of the fine-movement actuator, by which the gain of the fine-movement actuator can be estimated by an adaptive identification unit with high accuracy based on the control input to the fine-movement actuator and the head position signal.

Positioning control device for two-stage actuator

An actuator control device is provided for performing some modifications such as making the output of a disturbance observer zero for quickly restoring the proper tracking control if the out-of-track state takes place and if the outside force exceeding the maximum force generated by an actuator is applied to the device itself. In the actuator control device, a disturbance observer estimates disturbance added to the actuator. The second control signal corresponding to the estimated disturbance is added to the first control signal. The added signal is made to be a third control signal. Further, the second control signal is stored in a storage unit. The stored value is further added to the third control signal as the fifth control signal. By performing some modifications such as making the second control signal zero according to the abnormal state, this arrangement makes it possible to quickly restore the proper tracking control even if the out-of-track state takes place.

Actuator control device

A magnetic disk device comprises at least a disk having information, at least a head for reading or writing information from or into the disk, at least a micro actuator for supporting the head and positioning the head, a coarse actuator for carrying the micro actuator and positioning the head, a controller for controlling the micro actuator and the coarse actuator based on the servo information read by the head, and a host controller for determining that information is to be read. In the case where the host controller determines that the operation is in a wait mode, the positioning operation of the micro actuator is stopped.

Magnetic disk device including coarse and micro actuators

A magnetic disk apparatus includes a requesting unit for requesting the magnetic disk apparatus to re-set a value of specification information capable of determining performance of the magnetic disk apparatus in combination with either identification result or flag information; a performance unit for causing the magnetic disk apparatus which receives the request to re-set the own specification; a detecting unit for detecting an internal condition of the disk apparatus; a processing unit for processing the detection result; a conversion unit for converting the internal condition of the magnetic disk apparatus into states of a numeral value, a figure, a color, and a sound in combination with the process result, and for notifying the converted condition to a user; and a battery.

Disk apparatus and information processing system discriminative plural external electronic appliances

For detecting commutation timing of an inverter when operating a DC brushless motor under a starting thereof or a light load condition, with certainty, a micro-computer generates driving signals so as to drive switching elements of the inverter by PWM signals of those driving signals, in a predetermined order by every turn-on interval, thereby supplying driving current to the DC brushless motor, wherein a timing for exchange between the turn-on intervals (i.e., the commutation timing) is detected by detection of level of magnetic pole position detecting signals upon a basis of the PWM signals. Here, the minimum ON time of the PWM signals is set at a time being detectable in the level of the magnetic pole position detecting signals, however the frequency of the PWM signals is lowered when the DC brushless motor is operated in starting or under a light load condition, so as to make duty ratio of the PWM signals fit to the operation in the starting or under the light load condition, thereby enabling to ensure the minimum ON time of the PWM signals.

DC current brushless motor driving apparatus and air conditioner with using thereof

A positioning system of an optical disc apparatus includes focus error detecting part for detecting a focus error signal as a focal shift of a light spot related to an information recording surface of an optical disc, light spot moving part in the direction intersecting substantially perpendicularly to the optical disc surface, first digital arithmetic part for receiving the focus error signal and outputting a first control signal, second digital arithmetic part for receiving the focus error signal and a specified third control signal, performing arithmetic operations of a disturbance observer and outputting a second control signal, adding circuit for adding the first control signal and the second control signal and outputting the third control signal, drive circuit for driving the light spot moving part in a direction intersecting perpendicularly to the disc surface by the third control signal, wherein the first and the second digital arithmetic circuit perform arithmetic operations at different sampling periods.

Positioning device for optical disc apparatus

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Chiyoda, Japan

Atsushi Okuyama