Fujitsu Corporation

Hirofumi Ohsawa

Yukio Ozaki

Taizan Kobayashi

Toshinori Kasuga

Masanori Fukushi

Tohru Harada

Eiji Takada

Yoshinori Hino

Seiji Kino

A vibration extraction processing unit extracts a deflection component synchronous with a rotation from a clock signal of a non-contact sensor so as to correct a clock jitter. A clock generating unit generates a clock signal of any format frequency preliminarily set up according to the clock signal from the vibration extraction processing unit. A sector correction processing unit measures an error due to the frequency deflection so as to correct the writing start position for the format pattern signal of each sector containing a servo frame signal stored in a memory according to the measured error. Writing processing units read out the corrected format pattern signal from the memory according to a synchronous signal corresponding to a single turn of a disc and a format frequency clock signal and then writes into a disc medium face.

Servo track writing device and method thereof

A servo track writer for writing a servo track signal to a disk medium in a disk drive including the disk medium, a head for reading/writing information from/to the disk medium, and an internal actuator for moving the head across tracks formed on the disk medium. The internal actuator has a rotatable carriage for supporting the head. The servo track writer includes an external actuator having an arm, a solid deformation element provided in relation to the arm, and an effector mounted on the arm; an internal actuator control unit for controlling the internal actuator; an external actuator control unit for controlling the external actuator; a solid deformation element control unit for controlling the solid deformation element; and an arm position detecting device for detecting a position of the arm. The solid deformation element is divided into a first segment functioning as an actuator for minutely displacing the carriage, and a second segment functioning as a sensor for detecting a position of the effector.

Servo track writer and driving method therefor

A positioning device positions a driving unit of which a torque constant fluctuates depending on a position, whereby a proper quantization error is obtained even when a maximum current value in a movable range changes. The positioning device includes a position detector for detecting a present position of the drive unit, a control circuit for generating a digital drive command value corresponding to a positional error between a command position and a present position, a D/A converter for converting the digital drive command value into an analog voltage, and a driver, having a plurality of gains, for converting the analog voltage into the analog drive current with a selected gain. The control circuit selects the gain of the driver in accordance with the present position. The gain of the driver (voltage/current converting amplifier) is made variable and controlled corresponding to the position, and hence there is no necessity for covering the maximum current range with the digital command value. Therefore, the proper quantization error is obtained in the entire movable range, and the maximum current value needed in the position is obtained.

Precise positioning device and method for servo track writing

Growing community of inventors

Kawasaki, Japan

Hirofumi Ohsawa