Kabushiki Kaisha Toshiba

Koji Osafune

Yuji Sakai

Hiroshi Okamura

Koji Yano

Kazuhito Shimomura

Masahiro Kusunoki

Hiroyuki Kanda

Masahide Yatsu

Norio Yoshikawa

Tatsuharu Kusumoto

Toshikuni Sato

Kotaro Yamamoto

Tomihisa Ogawa

Hidetoshi Kawachi

Yusuke Ohinata

Hiroshi Suzuki

Masaaki Habata

Masaki Sano

Toshiyuki Fujioka

Yoshihisa Nakamori

Masahito Yamaguchi

According to one embodiment, a disk drive is provided which corrects already existing offset information according to a variation of a disk runout amount caused by an occurrence of a disk shift. The disk drive effects a head position adjustment at a head positioning control time with the use of offset information stored in a memory. A CPU measures a variation in the disk runout amount and phase caused by an occurrence of a disk shift resulting from an external shock involved and updates the existing offset information with a correction offset information based on a result of measurement.

Method and apparatus for head positioning control in a disk drive

A disk drive is disclosed which performs a head positioning operation capable of coping with a variation of an offset caused by a disk runout. A CPU of a head positioning control system calculates a second position offset amount by correcting a first position offset amount corresponding to a rotation angle of an actuator on a disk medium based on a disk runout amount. The CPU performs head positioning control including a position correction operation corresponding to a second position offset amount.

There is disclosed a servo writing method in which servo data is recorded by a perpendicular magnetic recording system. In the servo writing method, at the time of perpendicular magnetic recording of the servo data on a disk, a servo writing operation is executed including an offset process set based on the hard-easy transition shift (HETS) phenomenon.

Method and apparatus for writing servo data with perpendicular magnetic recording in a disk drive

A perpendicular magnetic recording disk drive is discloses which performs a head positioning control operation effectively against a hard easy transition shift (HETS) phenomenon. In the disk drive, a CPU performs an offset correcting operation in positioning control mode after a seek operation, using an offset value set on the basis of the HETS phenomenon from a memory when data is recorded.

Method and apparatus for head positioning control in perpendicular magnetic recording of disk drive

A perpendicular magnetic recording type of disk drive having function of removing a component of a shift in a base line of a reproducing signal is to be disclosed. The disk drive has a read channel including an extracting unit which extracts the component of the shift in the base line of the reproducing signal. The extracting unit includes low-pass filters, and parameters of a lower cut-off frequency of the low-pass filter are adjusted in read operation.

Method and apparatus for data reproducing in a disk drive

A disk drive to be used with the perpendicular magnetic recording method comprises a read/write gate generator that is adapted to regulate the timing of outputting a write gate signal and that of outputting a read gate signal. The generator regulates the output timings on the basis of the gap between the read head and the write head of the magnetic head unit of the disk drive and the data format on the disk. The generator has a DSP generator for generating a data sector pulse and delay circuits for regulating respectively the timing of the read gate signal and that of the write gate signal according to the data sector pulse.

Disk drive with control of read and write gate signals for read and write operation

A signal is read out from a two-layered perpendicular magnetic recording medium by a composite head formed from a single-pole perpendicular recording head and magnetoresistance effect type reproduction head. The read-out signal is amplified by a head amplifier, passed through a low-pass filter, and converted into a digital signal by an analog/digital converter. A DC restoring circuit restores a DC component removed by the head amplifier using the output signal from the analog/digital converter. An adder adds the restored DC component to the output signal from the analog/digital converter, thereby restoring the head output terminal signal. A servo demodulation circuit generates a position error signal on the basis of the restored signal.

Magnetic disk drive and position error signal generation method

Disclosed herein is a disk drive that can retract the head to a retract position by using a reserve power supply, when the supply of power from the main power supply is interrupted. The disk drive comprises a CPU, a control capacitor, an unload circuit, a reserve power supply, and a VCM. While the disk drive is operating normally, the CPU performs servo control, calculates a retract distance from the position of the head and determines a control value corresponding to the retract distance, by using the main power supply. The CPU converts the control value to a control voltage, which is held in the control capacitor. When the supply of power from the main power supply is interrupted, the unload circuit supplies a drive current set by the control voltage held in the control capacitor, from the reserve power supply to the VCM. The VCM moves the head to the retract position at an appropriate speed.

Apparatus and method for retracting the head on power down in a disk drive

Disclosed is a head loading/unloading type disk drive of retracting a head to a ramp by a reserve power supply upon power down of a main power supply. An unloading control system drives a VCM using a low-level voltage from the reserve power supply until the head reaches the ramp immediately upon power down of the main power supply. After the head reaches the ramp, the system applies a high-level voltage from the reserve power supply. The reserve power supply is made up of a rectifier for converting the back EMF of an SPM into a DC voltage. When a retract circuit detects power down of the main power supply, the DC voltage from the rectifier is limited to a low-level constant voltage by a constant voltage circuit, and applied to the VCM. When a ramp collision determining circuit determines collision of the head against the ramp, it controls the voltage applied to the VCM from the low-level voltage to a high-level voltage.

Apparatus and method for control head unloading on power down in a disk drive

On an FCP board and in a head amplifier circuit, provided for amplifying a read signal from a head and supplying the read signal to a read channel, a dummy wiring pattern is located near a wiring pattern for supplying the read signal. The head amplifier circuit incorporates a differential amplifier. The differential amplifier finds and amplifies a difference between the read signal supplied through the wiring pattern and the noise signal supplied through the dummy wiring pattern. The differential amplifier outputs to a read channel the read signal from which the noise has been removed.

Head signal device with noise immunity function, for use in a disk

The dimension ratio t/H of the thickness t of a flexure spring to the height (thickness) H of a slider 17 is set at 0.047 or less in order to reduce the variation in crown amount due to a temperature variation. As the ratio of the thickness t of the flexure spring to the height H of the slider decreases, the stress acting in the slider due to a difference in linear expansion coefficient between itself and the flexure spring decreases and the rigidity of the slider increases relative to the flexure spring. The dimension ratio H/L of the height H of the slider to the length L thereof is set at 0.245 or more. As the dimension ratio H/L increases, the rigidity of the slider increases and the amount of deformation of the slider due to a difference in linear expansion coefficient between itself and the flexure spring decreases. In addition, the ratio A2/A1 of an actual adhesion area A2 between the slider and a slider fixing portion of the flexure spring to a possible adhesion area A1 therebetween is reduced to 0.42 or less. Moreover, a temperature compensation member is adhered to the slider or the flexure spring.

Head assembly controlling distortion due to temperature variation and

To prevent a decrease in the window margin due to reproduced signals having asymmetrical waveforms in a magnetic recording and reproducing apparatus, data in which peak shifts occur are recorded in the SYNC regions in the data format for the recording medium in accordance with the recording method. In data read operation, by detecting the data recorded in the SYNC regions, the center of the data window signal is shifted by a desired peak shift amount.

Magnetic recording and reproducing apparatus

A magnetic recording/reproducing apparatus includes a control section, a recording section and a medium access section having a head. The control section sets a write mode in response to an input write access command, and outputs write data and density indication data to the recording section. In the write mode, the recording section generates dummy data in accordance with the density indication data and modulates a write current in accordance with the write data and the dummy data subsequent to the write data. The modulated write current is supplied to the medium access section. A value of the write current is determined in accordance with the density indication data, and the write current decays with a time constant while the write current is modulated in accordance with the dummy data. The medium access section write-accesses a medium in accordance with the modulated write current in the write mode.

Method of accurately executing read access and magnetic

A control apparatus for controlling the positioning of a head in a recording/reproducing apparatus is provided which comprises a carriage mechanism having a head, a switch for selecting one of a battery and a power source using commercial power source, a driving section for driving the carriage mechanism, in accordance with incoming velocity difference data, by a current which comes from a power selected by the switch, a velocity difference detector for generating the velocity difference data on the basis of incoming target velocity data and current velocity data and for delivering the velocity difference data to the driving section, a current position detector for detecting a current position of the head to produce current position data, a current velocity detector for generating the current velocity data from the current position data from the current position detector and a target velocity generator for generating the target velocity data on the basis of incoming target position data and the current position data from the current position detector and for delivering it to the velocity difference detector. The mode select signal is determined in association with the selection of the switch.

Method and apparatus depending on the selected power source for

A recording/reproducing system is provided with a PLL circuit for outputting data pulses and clock pulses on the basis of the read data reproduced from a magnetic recording medium. An external synchronization detection circuit is provided which detects the synchronization data (predetermined zero pattern data), recorded in synchronization areas of the magnetic recording medium, on the basis of the read data. When the synchronization data is detected, the synchronization detection circuit enables the PLL circuit to oscillate in synchronism with the read data. An internal synchronization detection circuit is provided, which detects the synchronization data (predetermined zero pattern data), as recorded in the synchronization areas of the magnetic recording medium, on the basis of data pulses derived from the PLL circuit and the clock pulses. A preventing circuit is further provided. When address mark data is not detected within a predetermined period of time after the external synchronization detection circuit detects th synchronization data, the preventing circuit prevents the PLL circuit from oscillating in synchronism with the read data.

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Ome, Japan

Koji Osafune