Fujitsu Corporation

Toshiba Storage Device Corporation

Isamu Tomita

Kazunori Mori

Yoshiyuki Kagami

Tomoaki Saito

Kenji Itou

Nobuyuki Suzuki

Takeyori Hara

Tsuyoshi Takahashi

Tatsuhiko Kosugi

Tatsuro Sasamoto

Masahide Kanegae

Ryuki Kubohara

Kouhei Takamatsu

Masao Kondo

Hiroyuki Tanaka

Hiroshi Tsurumi

Keiji Aruga

Shuichi Hashimoto

Hitoshi Kanai

Takao Koshikawa

Tadashi Nakamura

Hiroaki Ueno

Tsuyoshi Furukawa

Hideki Ohmori

Toshiki Kimura

Taturo Sasamoto

Nobuyuki Mitsunaga

Toshinori Hoshino

Masafumi Sato

Yoshihiro Nakao

A operation of storing a post code, which is read from each servo frame on a target track of a disk recording medium, in a memory if an on-track condition for determining that a head is controlled to be positioned on the target track is satisfied is executed. Next, a operation of using the post code, which is stored in the memory, for a correction of a demodulation position if the post code corresponding to each servo frame is stored in the memory and the on-track condition is satisfied in the correction of the demodulation position in each servo frame is executed.

Servo information correcting method

A magnetic disk incorporated into a magnetic disk device is divided radially into a plurality of areas. An inner-circumference area has servo information written thereon at a low frequency. An outer-circumference area has servo information written thereon at a high frequency. The magnetic disk device creates concentric tracks on the magnetic disk with a magnetic disk rotation center as the center of the concentric tracks and selects a dividing track that acts as a demarcation for switching the area from which servo information will be read. The magnetic disk device then deletes all the servo information that is not going to be read in each of the areas divided by the dividing track.

Magnetic disk device, servo-information writing device, magnetic disk, and magnetic disk device manufacturing method

To reduce power consumption of an information storage device, a control circuit for the information storage device stops the supply of a formatter clock or an ECC unit clock simultaneously with a seek operation. When a clock stop time has elapsed by the time obtained by subtracting at least a time required for restarting the formatter or the ECC unit from a seek time, the control circuit restarts the supply of the formatter clock or the ECC unit clock.

Control circuit for information storage device

Upon recording, a clearance control unit performs preheating by an added control value (BR) of a base heater control value B and an adjustment heater control value R and switches that to value B when it reaches a target sector to perform write. Upon reproduction, preheating is performed by the value (BR) and the value (BR) is maintained when it reaches a target sector to perform read. A correction processing unit detects contact between the head and a medium surface while increasing the value R from a predetermined initial value Ro, and sets a new calculated base heater control value B, and value Ro as the adjustment heater control value R. Write assist adjustment in which the measured adjustment heater control value R is adjusted to a heater control value that improves characteristic deterioration immediately after recording is started wherein preheating is switched to write heating is performed.

Control device, control method, and storage apparatus for controlling read head and write head clearance

A seek control apparatus for performing a seek control of a head comprises an MCU that acquires control information corresponding to the externally indicated data length out of the control information stored in a storage section storing the control information for seek control for each of a plurality of data length ranges and performs a seek control according to the acquired control information.

Seek control apparatus, seek control method and storage apparatus

In an apparatus for recording and/or reproducing information, which reproduces servo information being recorded on a medium and conducts a tracking operation based on the servo information, a power save part conducts a power save operation by reducing an operation clock frequency in accordance with a predetermined process during a tracking operation, during a seek operation, and/or during spindle motor startup.

Apparatus for recording or/and reproducing information and method for reducing power consumption thereof

A recording apparatus capable of securely reading out data for causing a head to follow along circular tracks set virtually. Therefore, on-track control along the virtual tracks is possible by the conversion data on the discoid record medium even when, for example, the printed circuit board in a recording apparatus has been replaced.

Recording apparatus having discoid record mediums

A disk device performs position control of a head. An acquiring unit acquires correction information and check information from a disk for checking the correction information. A judging unit judges whether the correction information acquired should be used for correcting position information recorded in the disk, based on the correction information acquired and the check information acquired.

Disk device

There are provided a storage apparatus and a computer-readable recording medium, on whose storage areas, servo frames are arranged at uniform intervals in a spoke-like pattern. Each of the servo frames has an index bit storing section storing, as an index bit, part of an index pattern, which is operable to identify a storage area. The apparatus and the recording medium have a storage area recognizing unit for recognizing the storage areas based on the index bits, which are obtained by an index bit obtaining unit. The index bits, stored one in each of the index bit storing sections of the servo frames, are adapted to form, when being sequentially arranged, an index bit string in which such an index pattern repeatedly appears.

Storage apparatus and storage medium

There is provided a head control method controlling move of a head on a discoidal recording medium including the steps of: partitioning the discoidal recording medium which has position information recorded thereon at radially equal spacing into a plurality of zones; and demodulating the position information using a coefficient set for each of the zones.

Head control method and recording apparatus

A disk drive device including a plurality of disks that are arranged concentrically about a central axis, wherein each of the disks includes a plurality of concentric tracks of different diameters. Each of the disks also includes a top surface and a bottom surface. There are a plurality of cylinders defined by a combination of one of the tracks from each of the disks, wherein each cylinder consists of a plurality of tracks of a single diameter. A plurality of heads are associated with the disks, wherein each of the heads is configured and arranged to access either a top surface or a bottom surface of one of the disks. The present invention also includes an upper level device for issuing access commands directing the heads to access the disks. When an access command is issued that requires sequential data to be accessed on more than one track, an access sequence is followed in which at least two of the top surfaces on different disks of the same cylinder are accessed directly after each other, or, at least two of the bottom surfaces on different disks of the same cylinder are accessed directly after each other.

Disk drive device and access sequence therefor

When a pin layer magnetic field offset judgment unit judges that a magnetic field in a pin layer of a spin valve head through which a sense current flows in the interference direction has been deviated from a normal direction, a recovery processing unit allows a recovery from the abnormality arising from the magnetic field offset. For example, the direction of the sense current is switched from the interference direction to the assist direction, and the sense current larger than that upon the ordinary reading action is allowed to flow so that the temperature of an antiferromagnetic layer exceeds the blocking temperature, whereby the direction of the magnetic field in the pin layer is modified to the normal direction by the action of a magnetic field generated from the sense current. After the modification, the sense current is returned to have its ordinary value in the interference direction.

Apparatus for recognizing spin valve head failure due to pin layer magnetic field offset

A register address and control data which were serially transferred from an outside by a serial interface unit are received, the received head address is stored into a head address control register, and a head selection signal corresponding to the head address is outputted. When the setting of an automatic head switching mode is received from the outside, an automatic head switching control unit automatically switches the contents of the head address control register and sequentially outputs the head selection signals to a plurality of heads synchronously with a write gate signal (WRGT signal) E,to instruct the writing operation from the outside.

Head IC and recording apparatus

A magnetic disk drive capable of specifying even the type of a medium defect with a small number of read/write operations is disclosed. A read signal is sampled. A defect detector,of a read channel IC includes a (1&plus;D) calculation circuit,for adding the current and preceding sample values or the absolute values thereof. The two types of sums of the current and preceding samples are compared with a lower reference value and an upper reference value preset in comparators,, respectively. A portion where the sum of the sample values exceeds the upper reference value is detected as a medium defect due to thermal asperity, a portion where the sum of the absolute values of the sample values is lower than the lower reference value is detected as a medium defect due to a missing, signal and a portion where the sum of the absolute values of the sample values exceeds the upper reference value as a medium effect due to an extra, signal thereby generating a defect detection signal DD. Three types of defects can thus be detected with a single read operation.

Magnetic disk drive with a disk medium defect detector and read channel IC used in the drive

A thermal asperity detection method includes the steps of (a) converting an analog signal reproduced from a magnetic recording medium into a digital signal using an analog-to-digital converter, (b) detecting thermal asperity based on the digital signal, and (c) automatically recognizing and managing detection of the thermal asperity by the step (b) by firmware.

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Kawasaki, Japan

Isamu Tomita