Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Hitachi Global Technologies Netherlands B.v.

Masashi Kisaka

Yutaka Ozawa

Kenji Toga

Isao Yoneda

Hiroshi Uchiike

Hiroshi Uchida

Fuminori Sai

Nobuyuki Kitazaki

Takashi Nakamura

Yuji Yokoe

Kazunari Tsuchimoto

Yoshiro Amano

Kazuaki Usui

Masaki Nagashima

Hidefumi Tominaga

Naoyuki Minami

Satoshi Hashimoto

Masahiro Shohda

Junichi Kimura

Sadamichi Sone

Koumei Hanaoka

A hard-disk drive (HDD). The HDD includes a main control circuit. The main control circuit includes a frequency-hunting peak filter. The frequency-hunting peak filter includes a peak filter wherein a gain at a center frequency becomes finite and a reciprocal of the transfer function is represented by z/Fin z-transform space. The denominator of the transfer function of the peak filter that is represented by F, has a real part that becomes zero at the center frequency and an imaginary part that becomes a positive number at the center frequency. In addition, the frequency-hunting peak filter includes a frequency updating unit that updates the center frequency to converge onto a frequency of disturbance by obtaining a comparative relation between the center frequency and the frequency of disturbance acting on the control system in accordance with a phase difference between an input and output of the transfer function represented by z/F.

Hard-disk drive

Embodiments of the present invention provide a disk drive capable of appropriately measuring non-linearity in a head position control system, and a control method therefore. According to one embodiment, a magnetic disk drive inputs a reference signal Sinto a voice coil motor, inputs into the voice coil motor a control signal Sin which a harmonic component resulting from the reference signal Sis suppressed, and measures an error signal PES that may be obtained in the state where the reference signal Sand the control signal S, in which the harmonic component is suppressed, are input in the voice coil motor.

Disk drive and controlling method thereof

Embodiments of the present invention provide a recording disk capable of curtailing the amount of servo data to be stored thereon, and a disk drive. According to one embodiment, servo data area sets each of a first servo data area and plural second servo data areas arranged in that order in a read direction HR are arranged successively on each of tracks of a magnetic disk. Stored in a second sector data section included in the second servo data area is data representing a distance in the read direction HR from the position of the first servo data area to that of the same second servo data area. The amount of data stored in the second sector data section is less than that of data stored in a first sector data section included in the first servo data area.

Recording disk and disk drive

An infinite impulse response (IIR) filter circuit in accordance with an embodiment of the invention has transfer function coefficients that are adaptively changed. Using a Nth-order polynomial A(z) and a polynomial B(z) whose order is not higher than N, the transfer function is defined by is also defined. The polynomial A(z) is transformed to make the term of the Nth power of z equal to 1. If the order of the polynomial A(z) is even, the polynomial A(z) is determined to satisfy the condition: If the order N is odd, the polynomial A(z) is determined to satisfy the condition: where l and k(i=0, 1, 2,,,) are real numbers.

Infinite impulse response filter circuit and magnetic disk drive

Embodiments of the present invention help to provide a magnetic disk drive that is capable of reducing a time period necessary for positioning a magnetic head when positioning the magnetic head by use of a dual-stage actuator. According to one embodiment, a main control circuit of a magnetic head device selects one of a seek mode and a positioning mode. The seek mode is to set a coarse adjustment control system to be a stable system by not causing control of a piezoelectric actuator to be performed by a fine adjustment control circuit. The positioning mode is to set the coarse adjustment control system to be an unstable system and setting a total control system inclusive of the coarse adjustment control system and a fine adjustment control system to be the stable system by causing the control of the piezoelectric actuator to be performed by the fine adjustment control circuit. Thereby the main control circuit causes the control system to operate.

Magnetic disk drive

Embodiments of the invention provide a servo information write method that makes it possible to properly locate the last-written servo information even when old servo information is overwritten by new servo information. In one embodiment, a servo track writer controller, which is within a servo track writer, reads a serial number (S/N) from a HDD (step), and acquires a magnetic disk drive servo information write count (P-ID) from a manufacturing process host (step). The next step (step) is then performed to control a positioner and a read/write channel so as to start writing servo information onto a magnetic disk. Servo information is sequentially written until the last track is written into (step). When the Nth servo information is to be written, a P-ID (N) is written subsequently to a burst signal (step). When the last track is written into in step, stepis performed to notify the manufacturing process host that the Nth servo information write is performed. Then, the servo information write process ends.

Servo information write method and apparatus

Embodiments in accordance with the present invention provide a drive unit that is capable of satisfactorily performing the positioning control with disturbance components included in a position error signal being effectively controlled. According to one embodiment, an error signal generator of a drive unit generates a position error signal (PES) on the basis of servo data read out from a magnetic disk. On the assumption that a frequency of a periodic variation component included in the PES is a target frequency, if a target frequency deviates from an effective frequency range of a digital filter, a downsampler down-samples the PES, and then supplies the PES to the digital filter so that the effective frequency range is shifted. As a result, within the shifted effective frequency range, a setting changing unit can control a setting frequency of the digital filter so that the setting frequency follows the target frequency. Therefore, it is possible to effectively reduce a signal component of the target frequency (a periodic variation component included in the PES).

Drive unit

Embodiments in accordance with the present invention provide a magnetic disk drive capable of alleviating an adverse effect of vibrations inherent to a housing on positioning control, reducing the adverse effect over other frequency range, and stabilizing the positioning control. In a magnetic disk drive according to embodiments of the present invention, a position control circuit that controls the position of a magnetic head produces a signal, based on which the position of the magnetic head is controlled, according to positional information read by the magnetic head. The signal is transmitted via a multi-rate filter circuit that decreases a sensitivity function relevant to a predetermined object frequency by a first predetermined gain, and suppresses an increase in the sensitivity function relevant to frequencies lower than the object frequency to a second predetermined gain.

Embodiments of the invention reduce the information (storage) overhead for determining the rotational position of a magnetic disk medium, as well as reducing the rotational position detection time. In one embodiment, a sector servo magnetic disk medium is configured such that: each track is divided into blocks each including a series of sectors; each block stores a positional information bit string as rotational position information; the positional information bit string is made up of a position code and an identification code, the position code including a block number, the identification code being used to identify the start or the end of the position code; and each bit of the positional information bit string is stored in a different sector of the block. When each block is made up of 12 sectors, for instance, if the block number is denoted as bbbbbb, the positional information bit string may be expressed as 00001bbb1bbb, where the first 5 bits '00001' constitute an identification code.

Magnetic disk medium, magnetic disk drive, and method for detecting rotational position of magnetic disk medium

An information recording method in a rotating storage apparatus comprising a rotating recording medium for recording information, a head for performing at least a write operation onto the rotating recording medium, and an acceleration sensor for detecting a shock. The method comprises outputting a shock out signal if an output from the acceleration sensor exceeds a predetermined threshold. A signal is output at a first level for a write inhibit period in response to the input of the shock out signal, where the write inhibit period is selected based at least in part on a time span in which the output of the acceleration sensor exceeds the predetermined threshold. Writing to the rotating recording medium is prohibited during the write inhibit period.

Shock resistant, high reliability rotating magnetic storage device and method

Embodiments of the invention provide a magnetic disk drive that exhibits excellent overall stability of a feedback control system even when the preset frequency for a peak filter significantly changes. In one embodiment, the symbol P denotes a VCM model, which outputs a head current position signal. The symbol C denotes a controller. The controller inputs a position error signal PES that is derived from a head current position signal output from the P, and outputs to addition point a control signal of a drive device for moving a magnetic head. Signal x to which disturbance noise is added enters a peak filter. The output y from the peak filter is output to addition point via a phase determination filter and added to a control signal output from the controller. A phase comparison frequency updater compares the phase of the position error signal against the output signal phase of the peak filter, changes the preset frequency for the peak filter in accordance with the result of comparison, and changes a transfer function for peak filter phase determination in accordance with a change in the preset frequency.

Servo control for magnetic disk drive

Embodiment of the invention inhibit an effect of repeatable runout errors without expanding servo data areas of the magnetic disk. With regard to low frequency components of positional information read by a magnetic head, which are substantially equivalent to a rotational frequency of a magnetic disk, a servo controller according to one embodiment includes: a peak filter for removing such low frequency components from the positional information; a correction module for correcting the positional information by using repeatable runout compensation data; a phase correction circuit for calculating the amount of control based on an output of the correction module; and an adding circuit for adding an output of the peak filter and an output of the phase correction circuit. The servo controller controls positioning of the magnetic head by calculating an amount of positioning control of the magnetic head based on the positional information and adding it to the amount of control calculated based on the positional information and the repeatable runout compensation data.

Servo controller in magnetic disk drive

Embodiments of the invention eliminate noise from burst signals by use of a reliable and simple method. In one embodiment, the read processor of the HDD has a noise elimination circuit. The noise elimination circuit retains multiple integral values of the waveform absolute values for each period in the burst signals read out from the head, then removes a maximum value and/or a minimum value from the multiple integral values, and transmits the remainder as noise-eliminated signal data. The noise elimination circuit is a circuit for eliminating noise from an N number of periods of burst signal data, and this circuit integrates the absolute values of the waveforms for each period in the N number of periods of burst signal data, compares the integral values of each period with one another, and outputs the remainder obtained by removing the maximum and minimum integral values, to the servo data decoder of the following stage.

Disk device, and positioning control method and signal-processing circuit for head

Embodiments of the invention compensate for repeatable run-out errors without causing servo system instability. In one embodiment, HDD has a peak filter on a feedback route of a servo system. The peak filter is designed so that a rotating frequency of a magnetic disk, the high-frequency components contained in the rotating frequency and a peak match the rotating frequency and the high-frequency components. Insertion of a required peak filter into the servo system allows compensation for a repeatable run-out (RRO) error due to an event such as a deviation from the roundness of a track. Also, since a Nyquist diagram of the system satisfies required characteristics, a repeatable run-out error may be compensated for without causing instability of the servo system due to use of the peak filter.

Disk drive, positioning method for head, and servo system

A technique for adaptively and stably updating the feed forward value required to drive the head of a rotational recording apparatus. A trajectory of a target position is generated for each seek command by using a compound function comprising a ramp function and a sine-wave function. The sine-wave element of the target position is transmitted to an adaptive filter for updating coefficients of the compound formula. All elements other than the sine-wave element are removed to provide a smooth update of the compound function's coefficients.

Growing community of inventors

Kanagawa, Japan

Masashi Kisaka