Abstract: A waveform generator generates an acceleration orbit, a velocity orbit, and a position orbit from the seek time. Each orbits multiplied by respective gains, whereupon the orbits are synthesized by a first adder. The resulting composite orbit is multiplied by a seek distance and then passed through a FIR filter to obtain the target position orbit that is to be applied to the later-stage two-degree-of-freedom control system. The two-degree-of-freedom control system has a characteristic whereby it is able to approximate a second-order low-pass filter.

Abstract: A position control device corrects the displacement of the head by disturbance applied to the disk device by the control system. An adaptive control to an unknown disturbance frequency is performed. The frequency estimation block for estimating the external vibration frequency from a signal that is based on the position error according to the adaptive rule, and a correction table for sequentially correcting the constants of the compensator using this external vibration frequency, are provided. Since the constants of the compensator are sequentially corrected according to the estimated angular frequency, highly accurate follow up control to an external vibration frequency in a wide range becomes possible.

Abstract: A master-disk producing device produces a master disk with master-disk identification information added. A disk producing device produces a first disk with the master-disk identification information added, using the master disk with the master-disk identification information added. A first disk device obtains, after the first disk with the master-disk identification information added is mounted, first correction information from a correction-information storing device based on the master-disk identification information of the first disk.

Abstract: A head position control system control the position of the head by correcting the components synchronizing rotation of the disk from the head control amount, in which an adjusted gain to minimize the components synchronizing rotation after correction is theoretically acquired. An adjusted gain based on the ratio of the magnitude between the components synchronizing rotation of a disk and the components not synchronizing rotation of the disk in the position signals is used. And a gain to minimize RRO after correction can be theoretically determined using an expression to determine RRO after correction. The gain can be determined without depending on experiment, and the value of RRO after correction can be guaranteed, therefore the manufacturing time and the device specifications can be determined.

Abstract: A head position control system control the position of the head by correcting the components synchronizing rotation of the disk from the head control amount, in which an adjusted gain to minimize the components synchronizing rotation after correction is theoretically acquired. An adjusted gain based on the ratio of the magnitude between the components synchronizing rotation of a disk and the components not synchronizing rotation of the disk in the position signals is used. And a gain to minimize RRO after correction can be theoretically determined using an expression to determine RRO after correction. The gain can be determined without depending on experiment, and the value of RRO after correction can be guaranteed, therefore the manufacturing time and the device specifications can be determined.

Abstract: A position control device corrects the displacement of the head by disturbance applied to the disk device by the control system. An adaptive control to an unknown disturbance frequency is performed. The frequency estimation block for estimating the external vibration frequency from a signal that is based on the position error according to the adaptive rule, and a correction table for sequentially correcting the constants of the compensator using this external vibration frequency, are provided. Since the constants of the compensator are sequentially corrected according to the estimated angular frequency, highly accurate follow up control to an external vibration frequency in a wide range becomes possible.

Abstract: A head positioning method and device positions a head which reads a disk-type storage medium at a specified location, and accurately estimates a bias value during settling control. A disk device includes a disk medium, a head, an actuator, and a control circuit, and settling control is performed based on a detected position after coarse control without integral compensation or bias compensation having been performed. The position of the head for a next sample is estimated, and an initial bias value is estimated from the difference between the detected position and the estimated position. This initial bias value is then used to perform settling control together with integral compensation of bias compensation. Since the accurate initial bias value at the start of settling is estimated, it is possible to reduce the time for correcting the shift in the bias during settling control, and greatly reduce the time required for settling control.

Abstract: A disk device that has displacement of servo signals in the circumference direction and radius direction between a plurality of disks, prevents a drop in performance due to the displacement when the heads are switched. To deal with the displacement in the circumference direction, the sector numbers on the disk are converted by a table for each head. Also the servo gate time is corrected by the table according to the eccentricity of the disk, so the servo signal detection accuracy improves. Also to deal with the displacement in the radius direction, the track numbers on the disk are converted by the table using the difference value based on the reference head.

Abstract: A head position control method controls the position of a head by correcting components synchronizing rotation of a disk based on the head control amount. A correction signal for components synchronizing rotation is generated by using a filter function. The filter function that integrates the sine and cosine terms of DFT and inverse DFT and forms multiply of the complex values a(m) and b(m) and sine and cosine for frequency conversion, is measured in advance. The complex values are the m degree of RRO frequencies having frequency characteristics to be multiplied (1+C(z)P(z)) or ?(1+C(z)P(z)/P(z)).

Abstract: A disk device for positioning a head to read a disk medium at a predetermined position demodulates accurate demodulation positions even when the head is moving. In a disk device that includes a disk medium, a head, an actuator and a control circuit, the demodulation result is determined from the position signal of the head and speed is corrected by a correction value which depends on the moving speed of the head. Since the speed is corrected, accurate positions can be demodulated even when the head is moving.

Abstract: A head position control system control the position of the head by correcting the components synchronizing rotation of the disk from the head control amount, in which an adjusted gain to minimize the components synchronizing rotation after correction is theoretically acquired. An adjusted gain based on the ratio of the magnitude between the components synchronizing rotation of a disk and the components not synchronizing rotation of the disk in the position signals is used. And a gain to minimize RRO after correction can be theoretically determined using an expression to determine RRO after correction. The gain can be determined without depending on experiment, and the value of RRO after correction can be guaranteed, therefore the manufacturing time and the device specifications can be determined.

Abstract: A head positioning method and device positions a head which reads disk-type storage medium at a specified location, and accurately estimates estimates a bias value during settling control. A disk device includes a disk medium, a head, an actuator , and a control circuit, settling control is performed based on a detected position after coarse control without integral compensation or bias compensation having been performed. The position of the head for a next sample is estimated, and an initial bias value is estimated from the difference between the detected position and the estimated position. This initial bias value is then used to perform settling control together with integral compensation of bias compensation. Since the accurate initial bias value at the start of settling is estimated, it is possible to reduce the time for correcting the shift in the bias during settling control, and greatly reduce the time required for settling control.

Abstract: A head position control method performs virtual circular control which does not follow the eccentricity of a disk, and implements high precision virtual circular control, even if the servo signals of an area demodulation method are used. The method performs virtual circular control by demodulating position signals in the area demodulation method and calculates the demodulation position with the velocity offset correction of 2-phase servo signals by using both the head velocity V of the virtual circular orbit reference and the relative velocity ?V of the virtual circular orbit and the position signal.

Abstract: A head positioning method and device positions a head which reads a disk-type storage medium at a specified location, and accurately estimates a bias value during settling control. A disk device includes a disk medium, a head, an actuator, and a control circuit, and settling control is performed based on a detected position after coarse control without integral compensation or bias compensation having been performed. The position of the head for a next sample is estimated, and an initial bias value is estimated from the difference between the detected position and the estimated position. This initial bias value is then used to perform settling control together with integral compensation of bias compensation. Since the accurate initial bias value at the start of settling is estimated, it is possible to reduce the time for correcting the shift in the bias during settling control, and greatly reduce the time required for settling control.

Abstract: A head position is demodulated by two-phase servo signals of PosN and PosQ from output of the head, so as to acquire a more accurate demodulated position. Saturation of PosN and PosQ is judged from the ratio of each absolute value of PosN and PosQ, and a different demodulating method is used for a saturated area and for an unsaturated area, and a demodulating formula is constructed so that the edge of each demodulating area matches with the edge of the adjacent demodulating area. Also saturated/unsaturated is judged by comparing the absolute value of PosN and the absolute value of PosQ, and determining whether the ratio thereof is greater or small than a predetermined saturation coefficient r.

Abstract: In a head positioning method and device in which the position of servo signals between heads is not uniform, it is aimed to reduce the time taken to find the servo signals when heads are switched. A storage disk device comprises storage disks with the servo signals, a plurality of heads that read the information from the storage disks, an actuator that moves the heads, and a control circuit that positions the heads based on the servo signals read from the storage disks by a selected head. This control circuit includes a synchronization circuit that, in response to a head switching cue, synchronizes the time of a servo gate signal (of the head to which switching is directed) for detecting a servo signal with the time of the servo signal read by the head to which switching is directed, and a processing circuit that reads the servo signal for the head in response to the synchronized detection signal and positions the head in response to the servo signal read.

Abstract: Position information PosN and PosQ are compared and position information Pos1 and Pos2 in which influences of an error of a position sensitivity gain appear oppositely are calculated. Subsequently, a weight gain G1=M and a weight gain G2=(1?M) are obtained from the position information Pos1. A multiplication value obtained by multiplying the third position information Pos1 by the weight gain G1 and a multiplication value obtained by multiplying the fourth position information Pos2 by the weight gain G2 are added and synthesized, thereby calculating a decoded position.

Abstract: A disk device has eccentric misalignment between a plurality of disk surfaces. In order to prevent transient phenomena due to differences in the eccentric trajectories during head switching, a head position control method performs feed forward control for a plurality of disk surfaces by application of the eccentricity correction current of respective heads, and when switching heads, predicts the velocity fluctuation or current step differential between heads from the eccentricity correction current, and thus corrects the control system to eliminate velocity fluctuation and current step differential.

Abstract: A head position is demodulated by two-phase servo signals of PosN and PosQ from output of the head, so as to acquire a more accurate demodulated position. Saturation of PosN and PosQ is judged from the ratio of each absolute value of PosN and PosQ, and a different demodulating method is used for a saturated area and for an unsaturated area, and a demodulating formula is constructed so that the edge of each demodulating area matches with the edge of the adjacent demodulating area. Also saturated/unsaturated is judged by comparing the absolute value of PosN and the absolute value of PosQ, and determining whether the ratio thereof is greater or small than a predetermined saturation coefficient r.

Abstract: This invention relates to a head position control method for a disk device that uses a disk medium whose tracks have been formatted externally, and a disk device that effectively uses the range of motion of an actuator. In a disk device that has a disk medium, a head, an actuator, a control circuit, there is a conversion mechanism that sets a data area in the writing range of the disk that corresponds to the range of motion of the actuator, and converts a logical address to a physical address in the data area. This invention makes it possible to set a storage capacity that makes maximum use of the range of motion of the actuator for any device, even when there is a position offset in the range of motion of the actuator.