Abstract: A method of servo writing is disclosed in which a servo writer incorporated in a disk drive writes a servo pattern into a disk medium. The servo writer controls positioning of a head on the basis of a basic servo pattern recorded on the disk medium to write a new servo pattern in the vicinity of the basic servo pattern. During this positioning control, the servo writer calculates a shape distortion of the basic servo patterns to correct a position of the head.

Abstract: Disclosed herein is a control system designed to position a head provided in a magnetic disk drive. The system has a controller, a signal output section, two gain/phase control sections and an adder. The controller receives data generated from position data extracted from servo data and representing the position of the head and generates, form the data, an operation signal. The operation signal is used in seek control or track following control to move the head to a target position. The signal output section distributes the operation signal to the gain/phase control sections. The gain/phase control sections adjust the phase and gain of the operation signal, independently of each other, generating gain/phases. The operation signals are supplied to the adder. The adder adds the signals, generating a control signal that has a gain smaller than the gain of the operation signal. The control signal is input to the object which is provided in the magnetic disk drive and which is to be controlled.

Abstract: The magnetic disk apparatus and methods for writing servo data in the magnetic disk drive apparatus detects a relative position between a magnetic head and a writing surface and performs a feedback on the detected relative position for determining the servo data writing position. Based on reference servo patterns that are preliminarily recorded on a portion of at least one surface of the disk, two pairs of head elements, arranged facing respective surfaces of the disk, alternately perform postscript operations of servo patterns while reducing a relative position error between the head and the disk in order to increase writing accuracy of the servo patterns writing operation.

Abstract: There is disclosed a self-supporting-type servo writing apparatus in which a head of a disk drive is used to write a servo pattern on a disk. In the disk drive, the disk is incorporated in which a clock pattern is pre-written as a signal pattern for position detection in a rotation direction. The servo writing apparatus uses the servo pattern written on the disk by a write head device to successively add the servo pattern into the whole surface on the disk.

Abstract: Disclosed herein is a disk drive that includes a head, an actuator holding the head, and a control section for driving and controlling the actuator. The control section includes a control system and a head-positioning system. The control system performs multi-rate control to adjust the velocity of the actuator while the head is being loaded and unloaded. The control system also suppresses a gain corresponding to a specific frequency component of the mechanical resonance of the actuator, by performing the multi-rate control.

Abstract: The magnetic disk apparatus and methods for writing servo data in the magnetic disk drive apparatus detects a relative position between a magnetic head and a writing surface and performs a feedback on the detected relative position for determining the servo data writing position. Based on reference servo patterns that are preliminarily recorded on a portion of at least one surface of the disk, two pairs of head elements, arranged facing respective surfaces of the disk, alternately perform postscript operations of servo patterns while reducing a relative position error between the head and the disk in order to increase writing accuracy of the servo patterns writing operation.

Abstract: A system for positioning a head in a target position on a disk in a disk drive is realized by combining a feedback control system and a feed forward control system that is a learning system. The feed forward control system observes the position error computationally determined by the feedback control system and detects a track eccentric factor synchronized with the revolution of the disk from the outcome of the observation. The feed forward control system generates an oscillation with a predetermined frequency (sine wave) different from the period of revolution of the disk and adds it to the position error from the feedback control system. The feed forward control system then computationally determines a control value (Uf) for removing the synchronous factor (track eccentric factor) correlated among a plurality of tracks from the position error.

Abstract: A servo system uses a disk on which two pairs of burst data items A and B and burst data items C and D are prerecorded, and the servo system performs positioning control for positioning a head within a range of a track on a disk. The servo system sets a range of a track to be divided into a first area regarding the track center as a reference position, a second area regarding a boundary position between tracks as a reference position, and a third area regarding a middle position between the reference positions, as a reference position. In the first area, the servo system calculates position information of the head by a first calculation formula using the burst data items A and B. In the second area, the servo system calculates position information of the head by a second calculation formula using the burst data items C and D. Further, in the third area, the servo system calculates an average value of calculation results from the first and second calculation formulas, as position information.

Abstract: A head positioning control system for use in a HDD and arranged to position a head in a target position has different seek control systems arranged to be operated respectively when a read access is made and when a write access is made. When the read access is made, the system using target velocity data for controlling read seek executes read seek control. When the write access is made, the system using target velocity data for controlling write seek executes write seek control. The read seek control allows the head to be moved to the target position at relatively high velocity. The write seek control allows the head to relatively stably and accurately reach the target position.

Abstract: In a disk drive, the CPU uses the cylinder code recorded on the servo area on the disk and thereby senses the present position of the read head. The cylinder codes are the addresses of the tracks formed on the disk and indicate the track position of the read head. In the servo area, the redundant data for identifying the boundary between adjacent tracks is recorded in addition to the cylinder code. When the read head is located near the track boundary, the CPU receives the cylinder code and redundant data and thereby determines which one of the boundaries with adjacent tracks to the track identified by the cylinder code the read head is located nearby. This makes it possible to determine the present position of the read head even when the read head accurately is positioned near the boundary between adjacent tracks.

Abstract: The present invention relates to a head positioning control system for controlling to move a head to a target position on a disk as a recording medium on the basis of servo data recorded on the disk in a disk drive. A speed control section calculates a model acceleration for the head on the basis of the distance between the target position and a model position. A model section models movement control for moving the head to the target position, on the basis of the model acceleration. The model position is updated by calculation in the model section. A correcting value for correcting the model acceleration is calculated on the basis of a displacement of the actual position of the head from the calculated model position. An actual machine section performs movement control for moving the head to the target position on the basis of the sum of the model acceleration and the correcting value. The actual position is updated by calculation in the actual machine section.

Abstract: A head positioning system includes a feedforward operation controller which calculates a basic head position control signal to output to a head displacement providing device based upon the target track the head is to be moved to and the present head position at the time when a head positioning operation begins. Subsequently, a feedback corrected control signal for head positioning is calculated by a feedback operation controller using a detected signal indicating actual head position relative to the record disk. Until the results from the feedback operation controller are available, the basic head position control signal is utilized for the head positioning operation. This basic head position control signal is also used for controlling head positioning whenever an output from the feedback operation controller is not being provided.