JP2001250349A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high-speed high-accuracy positioning of a magnetic head by subjecting a micro-drive actuator of a piggy bag actuator having a main drive actuator and the micro-drive actuator to high-band controlled driving and to realize a high-recording density magnetic disk. SOLUTION: The magnetic disk device has a magnetic disk 1 to which information data is recorded, a composite type head section 2 which consists of an inductive head for recording the data on the magnetic disk and a magneto- resistive head for reproducing the data, a slider 3 which is mounted with the head section and is driven by an auxiliary drive means and a magnetic head supporting mechanism section 4 which supports the slider, faces the magnetic disk described above and is driven by a main drive means 5-1. The position signal of the head is formed in accordance with the reproduced servo information and the auxiliary drive means 5-2 is so controlled as to approach a target position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive for positioning a head.

[0002]

2. Description of the Related Art In recent years, with the development of multimedia,
There is a strong demand from the market for a high-density magnetic disk device that accesses a target position at a high speed (positions a head portion) and records and reproduces a large amount of video information, audio information, character information, and the like. Various high-speed and high-accuracy positioning techniques have been proposed. In order to realize a higher recording density of a magnetic disk device, a recent magnetic disk device is composed of a reproducing head composed of a GMR head to which a magnetoresistive effect is applied, and a recording head composed of an inductive head. A composite magnetic head (referred to as a "head unit") is employed. The composite magnetic head (head unit) including the two types of heads is mounted on the same slider. A slider on which the head is mounted is mounted on a head support mechanism, and the head support mechanism is configured to be rotatable about an axis mounted on a chassis (rotary actuator). A rotary actuator is suitable for realizing high-speed access because the influence of inertia can be reduced.

In recent research papers, various magnetic disk devices having two driving units, a main driving unit and an auxiliary driving unit, for performing high-speed and high-precision positioning of a magnetic head have been proposed. A main driving unit such as a voice coil motor moves the head support mechanism, the head, and the slider by rotating the head support mechanism about an axis attached to the chassis. The main drive means is mainly used for large movement such as seek / settling and multiple track jumps. The auxiliary driving means is
Drive the head or slider. The auxiliary driving means is mainly used for high-speed and fine positioning such as track following and one-track jump. The reproducing head reads servo information (information on the current position of the head) recorded on the magnetic disk. Based on the servo information,
By controlling the main driving means and the auxiliary driving means,
The head portion formed on the slider can be accessed (positioned) at an arbitrary position on the magnetic disk.

A mechanism having a main driving means and an auxiliary driving means is generally called a piggyback actuator. Hereinafter, a conventional example of a piggyback actuator will be described. FIG.
Conventional example 1 shown in FIGS. 8 and 23 is the invention described in Japanese Patent Application Laid-Open Publication No. 9-82048. Conventional example 2 shown in FIGS. 19 and 24 is a publication (IEEE).
E TRANSACTIONS ON MAGNETI
CS VOL. 35 No. 2 MARCH 1999)
The invention described in the above. Conventional example 3 shown in FIGS. 20 and 25 is a publication (IEEE TRANSACTION).
NS ON MAGNETICS VOL. 32 N
o. 5 SEPTEMBER 1996). Conventional example 4 illustrated in FIG. 21 is an invention described in a domestic publication (WO98 / 19304).
Conventional example 5 shown in FIG. 22 is an invention described in Japanese Patent Application Laid-Open Publication No. 9-231538. In addition,
In the drawings of the cited examples cited above, the symbols in the drawings cited above have been changed from the symbols described in the official gazettes and the like in order to prevent the symbols from being mixed. Also, for easy comparison with the present invention, the names of some of the parts are changed as long as the identity is not lost.

[Explanation of FIG. 18] The piggyback actuator of the prior art 1 of FIG. 18 is a head actuator mechanism diagram described in Japanese Patent Application Laid-Open Publication No. 9-82048. In FIG. 18, Conventional Example 1 includes a voice coil motor 901 as a main driving unit and a piezoelectric element 902 as an auxiliary driving unit. Voice coil motor 901 rotates the entire head actuator mechanism about axis 905. The portion 906 corresponds to the head support mechanism of the present invention. The piezoelectric element 902, which is disposed substantially at the center of gravity of the head actuator mechanism, minutely drives the support arm 903 (corresponding to the head slider of the present invention) in the direction of the arrow shown in FIG. Make movement adjustments.

[Explanation of FIG. 19] A piggyback actuator according to prior art example 2 in FIG. 19 is disclosed in IEEE TRA.
NSACTIONS ON MAGNETICS VO
L. 35 No. FIG. 2 is a configuration diagram of a head actuator described in 2MARCH 1999). Head part 91
1 and the view including the slider 912 and the view including the piezoelectric element 913 are exploded views of the microactuator 914. In this specification, "microactuator"
Means the entirety of the auxiliary drive means and the mechanism section (including the head section) driven by the auxiliary drive means. In FIG. 19, Conventional Example 2 includes a main driving unit (not shown) and a piezoelectric element 913 as an auxiliary driving unit. Although the primary drive is not described, it is likely that the primary drive will rotate the entire head actuator about axis 915. The portion 916 corresponds to the head portion support mechanism of the present invention. The piezoelectric element 913 performs a push-pull operation to minutely drive a slider 912 (corresponding to a head slider of the present invention) on which the head unit 911 is mounted, right and left.

[Explanation of FIG. 20] A piggyback actuator mechanism of prior art example 3 shown in FIG.
RANSACTIONS ON MAGNETICS
VOL. 32 No. 5 SEPTEMBER 199
It is a block diagram of the head actuator described in 6). In FIG. 20, Conventional Example 3 includes a main driving unit (not shown) and an auxiliary driving unit including a yoke 923, a magnet 924, and a coil 925 using electromagnetic force. Although the primary drive is not described, it is likely that the primary drive will rotate the entire head actuator about axis 926. The portion 927 corresponds to the head portion support mechanism of the present invention. York 9
The auxiliary driving means including 23
A moment about the center 22 is given, and the head suspension assembly 921 is minutely driven. The head suspension assembly 921 driven by the auxiliary driving means corresponds to a head slider of the present invention.

[Description of FIG. 21] A conventional example 4 of FIG. 21 is a microactuator of a piggyback actuator described in a domestic publication (WO98 / 19304). The main drive means is not shown. In FIG. 21, the carriage arm 933 is considered to correspond to the head support mechanism of the present invention, and supports the illustrated microactuator. A slider 932 (corresponding to a head slider of the present invention) on which a magnetic head 931 (corresponding to a head portion) is mounted is supported by a stator plate 937. The head suspension 936 includes piezoelectric elements 934 and 935 serving as auxiliary driving means, the stator plate 937, and a fixed frame 938.
Stator plate 937 includes piezoelectric elements 934 and 935
And the piezoelectric elements 934 and 935 are fixed to the frame 938 to which the head suspension 936 is fixed.
Are connected in a hinge configuration. The fixed frame 938 is fixed to the carriage arm 933.
The push-pull operation of the piezoelectric elements 934 and 935 as auxiliary driving means drives the hinge mechanism,
The stator plate 937 is minutely driven in the direction of the arrow shown in FIG. Thereby, the stator plate 937
93 mounting a magnetic head 931 supported on the slider 93
2 is minutely driven.

[Description of FIG. 22] A conventional example 5 of FIG. 22 is a microactuator of a piggyback actuator described in Japanese Patent Application Laid-Open Publication No. Hei 9-231538. In FIG. 22, an element portion 931 having a recording / reproducing element (corresponding to a head portion of the present invention), a slider 932 (corresponding to a head slider of the present invention), and
Comb-shaped electrostatic actuator 9 as first auxiliary driving means
The microactuator including the actuators 34 and 935 and the shape memory actuators 936 and 937 as the second auxiliary driving unit is mounted on the head support mechanism 933. The main drive means is not shown. The comb-shaped electrostatic actuators 934 and 935 serving as the first auxiliary driving means are provided with a slider 932 on which the element portion 931 is mounted.
Are driven in the vertical direction in FIG. Shape memory actuators 936 and 937, which are second auxiliary driving units, drive a slider 932 on which the element unit 931 is mounted in the left-right direction in FIG.

The present invention provides a disk drive which realizes high-speed and high-precision positioning of a head using various piggyback actuators as described above. Therefore,
In the description and claims, "head part",
The terms "head slider" and "head support mechanism" should be interpreted broadly. "Head section" includes a reproducing head. The term “head section” is a concept that includes both a read head and a read head and a recording head. The term “reproducing head” is a concept that includes both a reproducing-only head and a recording / reproducing head. “Head slider” is a general name of a mechanism unit that mounts a head unit and can be driven by both the auxiliary driving unit and the main driving unit. As in the conventional example 1 shown in FIG. 18, the actuator in which the mechanical section 903 constituting the head slider is physically integrated with the mechanical section 906 constituting the head section supporting mechanism section also includes a head slider and a head section supporting mechanism. Included in an actuator having a portion. The "head support mechanism" is a mechanism that supports the head slider and supports the head in opposition to the disk.
This is a general name of a mechanism that is not driven by the auxiliary driving means but is driven by the main driving means.

Next, a conventional control method for performing high-speed and high-precision positioning using the piggyback actuator as described above will be described using Conventional Examples 1 to 3 described above.
explain. [Explanation of FIG. 23] FIG. 23 is a block diagram showing a control method of the piggyback actuator (FIG. 18) of the disk recording / reproducing apparatus of the first conventional example. In FIG. 23, an input signal E of the control system is a position error signal indicating a position error of the head 904 (FIG. 18) with respect to a target position. In
Considering the other descriptions, the output of the subtractor 946 is considered to be called the position error signal E). The read head reads the servo data (position information) recorded in advance in the servo area of the disk, knows the current position of the read head based on the read servo data,
The position error signal E is generated by calculating the error from the target position.

The position error signal E is input to the drive section 942 of the main actuator (corresponding to the main drive section control section and the main drive section of the present invention) via the compensator 941. On the other hand, the position error signal E is inverted in phase by the inverting amplifier 945, multiplied by a predetermined gain k by the gain unit 943, and
44. Inverting amplifier 945, gain unit 94
3 and the auxiliary actuator 944 correspond to an auxiliary drive unit control unit, an auxiliary drive unit, and a mechanical unit of the present invention. The main actuator (including a control unit, a driving unit, and a mechanical unit in FIG. 23) 942 and the auxiliary actuator (in FIG. 23, including a part of the control unit, the driving unit, and the mechanical unit) 944 operate. The head 3 is controlled to move to the target position. Therefore, the primary actuator 942
The auxiliary actuator 944 is also driven and controlled based on the input position error signal E.

FIG. 24 is a block diagram showing a control method of a piggyback actuator (FIG. 19) of the disk recording / reproducing apparatus of the second conventional example. In FIG. 24, a position error PES, which is a difference between a target position and a current position as a final output, is input to a microactuator controller (auxiliary drive control unit) 951. Microactuator controller (auxiliary drive means controller) 95
1 is a microactuator (auxiliary driving means) 952
Drive. The output signal of the microactuator controller (auxiliary driving means) 951 is also input to a relative displacement estimator (relative displacement estimator) 953. Relative displacement estimator (relative displacement estimator) 95
3 outputs the estimated relative displacement (estimated relative movement amount signal).
Actuator controller (Main drive control unit)
954. The coarse actuator controller (main driving means control unit) 954 is a coarse actuator controller.
The actuator (main driving means) 955 is driven. Although a description of this block diagram is not described, a relative displacement estimator (Relative Display) is not described.
It is considered that the relative movement amount of the head unit is estimated based on the output signal of the microactuator controller (auxiliary driving unit control unit) 951.

FIG. 25 is a block diagram showing a control method of the piggyback actuator (FIG. 20) of the disk recording / reproducing apparatus of the third conventional example. In FIG. 25, a position error E, which is the difference between the target position X and the current position that is the final output, is input to the milli-actuator controller (auxiliary drive control unit) 961. The auxiliary driving means control unit 961 independently calculates the control amount of the control target, and
The actuator (auxiliary drive means) 962 is driven. Similarly, the position error E is input to the coarse actuator controller (main drive control unit) 963.
The main drive unit control unit 963 independently calculates the control amount of the control target, and outputs a coarse actuator (main drive unit).
964 is driven. The plant 965 represents a mechanical unit to be controlled (including a main drive unit and an auxiliary drive unit).

FIGS. 26 to 41 show simulation results when the piggyback actuator is controlled by a conventional control method. In addition, since the details of the control circuit and the actual performance of the conventional example described in the above publication cannot be obtained, the inventor invented the conventional disk device based on the description in the above publication. It was constructed and its performance was measured by simulation.

FIGS. 26 to 29 show the response characteristics when the disk device is controlled by the voice coil motor (main driving means) alone. FIG. 26 shows a step response when the disk device is controlled by the voice coil motor (main driving means) alone. The step response indicates settling performance during seek and jump time performance during track jump in the disk device. 4, 10,
26, 30, 34, and 38, the target level on the vertical axis is 1, and the time on the horizontal axis is in seconds. The settling time for the head section to converge to the target position takes 4 ms or more. FIG. 27 shows a closed-loop frequency characteristic when the disk device is controlled by a single voice coil motor (main driving means). FIG. 5, FIG. 11, FIG.
In FIG. 31, FIG. 35, and FIG. 39, the upper part shows the gain characteristic, and the lower part shows the phase characteristic.

FIG. 28 shows a transition of the position error signal when a disturbance is applied when the disk device is controlled by the voice coil motor (main driving means) alone. The characteristic of the position error signal (position error suppression characteristic) indicates the tracking performance at the time of track following in the disk device, and furthermore, the track density. 6, 12, 28, 32,
In FIGS. 36 and 40, the position error signal indicates a position error when four types of position error factors are input to the servo system. The unit of the vertical axis is position error (bit), and the unit of the horizontal axis is second (S). A position error of 50 bits corresponds to about 10% of the track pitch. FIG. 29 shows a histogram of the residual position error at the time of settling when the disk device is controlled by the voice coil motor (main driving means) alone. The three sigma of the position error is 0.1337 μm.
The histograms of FIGS. 7, 13, 29, 33, 37, and 41 are shown in FIGS. 6, 12, 28, 32, and 3, respectively.
6 and the frequency distribution of each position error in FIG. 40. The vertical axis indicates frequency, and the horizontal axis indicates position error (bit number).

FIGS. 30 to 33 show response characteristics when the disk device is controlled by a microactuator (auxiliary driving means) alone. FIG. 30 shows a step response when the disk device is controlled by the microactuator (auxiliary driving means) alone. The settling time for the head section to converge to the target position is just over 1 ms. FIG. 31 shows frequency characteristics of a closed loop when the disk device is controlled by a single microactuator (auxiliary driving means). FIG. 32 shows a transition of the position error signal when a disturbance is applied when the disk device is controlled by the microactuator (auxiliary driving means) alone. FIG.
Shows a histogram of the residual position error at the time of settling when the disk device is controlled by the microactuator (auxiliary driving means) alone. The three sigma of the position error is 0.
0415 μm.

FIGS. 34 to 37 show a disk drive in which a voice coil motor (main drive means) and a microactuator (auxiliary drive means) are not linked to each other, as in the first and third conventional examples. FIG. 9 shows response characteristics when independently controlled based on error signals between the current position of the unit and the target position. FIG.
Indicates a step response. The settling time for the head to converge to the target position is less than 4 ms. FIG. 35 shows frequency characteristics of the closed loop. FIG. 36 shows a transition of the position error signal when a disturbance is applied. FIG. 37 shows a histogram of the residual position error at the time of settling. The three sigma of the position error is 0.0952 μm.

FIGS. 38 to 41 show response characteristics in the case where the same control system as that of the conventional example 2 is employed in the disk device. The microactuator is controlled based on an error signal between the current position of the head unit and the target position. In addition, the voice coil motor (main driving means) is controlled so as to estimate the relative movement amount of the head unit by the microactuator and eliminate an error obtained by subtracting the relative movement amount from the error signal. FIG. 38 shows the step response. The settling time for the head to converge to the target position is 1
ms. FIG. 39 shows frequency characteristics of the closed loop. FIG. 40 shows the transition of the position error signal when a disturbance is applied. FIG. 41 shows a histogram of the residual position error at the time of settling. 3 sigma of position error is 0.062
8 μm.

[0021]

SUMMARY OF THE INVENTION Conventional Example 1 and Conventional Example 3
As described above, the error signal between the current position of the head unit and the target position (error signal = target position−current position) is made zero without causing the main actuator and the auxiliary actuator to cooperate with each other. In the case of a control method in which each is controlled and the head unit is driven, when the response of the microactuator (the auxiliary drive unit and the mechanism unit driven by the auxiliary drive unit) is made to have a high band and the control band is made high, The settling time of a transient response such as a step response greatly deteriorates in performance as compared with the microactuator alone, and the position error suppression characteristic also deteriorates, so that the effect of the piggyback actuator cannot be sufficiently obtained.

In Conventional Example 2, the microactuator is controlled based on an error signal between the current position of the head and the target position. The output signal of the microactuator controller (auxiliary driving means) 951 is a relative
The displacement is inputted to a displacement estimator (relative displacement estimator) 953, and a relative displacement estimator (relative displacement estimator) 953 is inputted.
Estimates the relative movement amount of the head unit by the microactuator, adds the estimated movement amount by the microactuator to the current position of the head unit based on the signal reproduced by the reproduction head, and the added value is It is presumed that the main actuator is controlled so as to match the target position.

However, in the devices of the prior arts 1 and 3, the main drive means is controlled so that the relative movement amount of the head portion by the microactuator is estimated and the error obtained by subtracting the relative movement amount from the error signal is eliminated. Although the performance is improved, the settling time of the transient response deteriorates greatly compared to the microactuator alone, and the position error suppression characteristic also deteriorates, so that the effect of the piggyback actuator can not be fully exploited. Had a problem. Therefore, in a disk device such as an HDD, there is a problem that performance such as seek time and track jump time is deteriorated.

Further, since the operation range of the microactuator is small, it is necessary to operate within the operation range. Large movement must be performed by the main actuator, and minute movement such as track following must be performed by the microactuator. However, in the device of Conventional Example 2, the operation of the micro-actuator having a higher bandwidth is dominant, the main actuator hardly moves, and the micro-actuator is always driven to the operation limit in a continuous track jump or the like. There was a problem. When a piezoelectric element is used as the auxiliary driving means of the microactuator, for example, as in Conventional Examples 1, 2, 4, and 5, if the piezoelectric element is always driven to its limit, the displacement amount of the piezoelectric element changes with time, and sometimes fatigue. Destroy. In addition, since the piezoelectric element has hysteresis, driving the piezoelectric element all the way to the limit leads to deterioration in control accuracy.

In view of the above-mentioned problems, the present invention realizes high-speed and high-precision positioning of a head in a piggyback actuator having a main driving unit and an auxiliary driving unit by controlling a micro-actuator in a high band. It is another object of the present invention to provide a disk device having a high recording density (high track density).

[0026]

According to a first aspect of the present invention, there is provided a disk apparatus having first relative position detecting means for detecting or estimating a moving amount of a head unit by a main driving means, wherein the first relative position detecting means is provided. A piggyback actuator (having a main drive unit and an auxiliary drive unit) that controls the main drive unit based on information including the movement amount of the head unit detected or estimated by the position detection unit. According to the present invention, it is possible to obtain a disk device having a short settling time and a small residual position error during the setting. Accordingly, a disk device having a high recording density can be obtained.

The disk drive of the present invention includes an estimating means including main driving means estimating means for estimating the amount of movement by the main driving means, and auxiliary driving means estimating means for estimating the amount of movement by the auxiliary driving means. And, when the control unit is considered to be a multi-input multi-output system that outputs the control signal of the main drive unit and the control signal of the auxiliary drive unit, the control signal of the main drive unit and the control signal of the auxiliary drive unit At least one of the control signals is not interfered with by other control signals.

According to the present invention, the interference between the main driving means and the auxiliary driving means can be eliminated. As a result, the main drive unit and the auxiliary drive unit interfere with each other as in the conventional case, and the performance of the piggyback actuator is greatly deteriorated as compared with the microactuator alone, and the position error suppression characteristic is also deteriorated. The problem that the effect of the back actuator cannot be sufficiently obtained can be solved. According to the present invention, it is possible to obtain a disk device having a short settling time and a small residual position error during the setting. Accordingly, a disk device having a high recording density can be obtained.

According to a fourth aspect of the present invention, in the disk device, a first auxiliary driving unit control unit that controls the auxiliary driving unit so that the head unit approaches a target position, and a movement by the auxiliary driving unit. A second auxiliary driving unit control unit that controls the auxiliary driving unit so that the amount becomes zero or a constant value, the first auxiliary driving unit control unit, and the second auxiliary driving unit control unit.
And a control switching unit for switching any one of the auxiliary driving unit control units to operate effectively.

According to the present invention, it is possible to obtain a disk device having a short settling time and a small residual position error during the setting.
Further, according to the present invention, it is possible to obtain a disk device which does not excessively drive the auxiliary driving means. As a result, it is possible to reduce the change over time of the moving amount of the auxiliary driving means such as the piezoelectric element and extend the life of the auxiliary driving means. Further, since the hysteresis of the auxiliary driving means such as the piezoelectric element can be suppressed to a small value, the settling time can be shortened, and the residual position error at the time of the settling can be reduced.

A method of controlling a disk drive according to a ninth aspect of the present invention includes a first relative position detecting step of detecting or estimating a moving amount of a head unit by a main drive unit. The main drive unit of the disk device including the piggyback actuator (having the main drive unit and the auxiliary drive unit) is controlled based on the information including the detected or estimated movement amount of the head unit. According to the present invention, it is possible to obtain a method of controlling a disk device in which the settling time is short and the residual position error during the settling is small. Therefore, a control method for a disk device having a high recording density can be obtained.

According to a first aspect of the present invention, there is provided a disk on which information data is recorded, a head unit including a reproducing head for reproducing data recorded on the disk, and a head slider mounting the head unit. A head section supporting mechanism section supporting the head slider and supporting the head section in opposition to the disk, and a main driving section for driving the head section supporting mechanism section to move the head section; A disk device comprising: an auxiliary driving unit that drives the head unit or the head slider to move the head unit; and a control unit that controls the main driving unit and the auxiliary driving unit. A head position detecting means for detecting a current position of the head section based on a reproduction signal of the reproducing head; First relative position detection means for estimating, an auxiliary drive means control section for controlling the auxiliary drive means based on information including a position error between a target position of the head section and a current position of the head section, A disk drive, comprising: a main drive control unit that controls the main drive based on information including the movement amount of the head unit detected or estimated by the first relative position detection unit. It is. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to a second aspect of the present invention, the control unit further includes a head unit including a moving amount of the head unit by the main driving unit and a moving speed of the head unit by the main driving unit. Main driving unit estimating means for estimating the state amount of the head unit, wherein the main driving unit control unit controls the main driving unit based on information including the state amount of the head unit. A disk device according to claim 1. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to a third aspect of the present invention, the control section further includes a second relative position detecting section for detecting or estimating a moving amount of the head section by the auxiliary driving section. The first relative position detecting means is configured to calculate a moving amount of the head unit calculated based on a reproduction signal of the reproducing head and a moving amount of the head unit by the auxiliary driving means output by the second relative position detecting means. 2. The method according to claim 1, wherein the difference is estimated as an amount of movement of the head unit by the main driving unit.
Or a disk device according to claim 2. The present invention
This has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to a fourth aspect of the present invention, there is provided a disk on which information data is recorded, a head including a reproducing head for reproducing data recorded on the disk, and a head slider mounting the head. A head part support mechanism for supporting the head slider and supporting the head in opposition to the disk; a main drive unit for driving the head part support mechanism to move the head; A disk device comprising: an auxiliary driving unit that moves the head by driving the head unit or the head slider; and a control unit that controls the main driving unit and the auxiliary driving unit, wherein the control unit includes: A first auxiliary driving unit control unit that controls the auxiliary driving unit so that the head unit approaches a target position; and a moving amount by the auxiliary driving unit is zero. The second auxiliary driving unit control unit that controls the auxiliary driving unit, and one of the first auxiliary driving unit control unit and the second auxiliary driving unit control unit controls the auxiliary driving unit so that is a constant value. And a control switching means for switching to operate effectively.

The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Further, the present invention has an effect that a disk device which does not excessively drive the auxiliary driving means can be obtained. As a result, it is possible to reduce the change over time of the moving amount of the auxiliary driving means such as the piezoelectric element and extend the life of the auxiliary driving means.
Further, since the hysteresis of the auxiliary driving means such as the piezoelectric element can be suppressed to a small value, the settling time can be shortened, and the residual position error at the time of the settling can be reduced.

According to a fifth aspect of the present invention, the control unit further includes a second relative position detecting means for detecting or estimating a moving amount of the head unit by the auxiliary driving means. The driving unit control unit further controls the auxiliary driving unit based on information output from the second relative position detecting unit and including the amount of movement of the head unit. A disk device according to claim 4. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to a sixth aspect of the present invention, the second relative position detecting means includes a moving amount storing means for storing an actually measured moving amount of the head section by the auxiliary driving means, and the actually measured moving amount. 6. The disk device according to claim 5, further comprising: a relative position estimating unit that estimates an amount of movement of the head unit by the auxiliary driving unit based on the amount. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Therefore, by extension, a disk device with a high recording density
It has the effect of being obtained.

According to a seventh aspect of the present invention, the control section further includes a main drive section estimating section, wherein an output of the main drive section control section is not interfered with an output of the auxiliary drive section control section. The disk device according to any one of claims 1 to 6, further comprising:

The present invention has the effect of eliminating interference between the main driving means and the auxiliary driving means.
As a result, the performance of the piggyback actuator is greatly degraded as compared with the microactuator alone, and the position error suppression characteristic is also deteriorated. Can be solved. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to an eighth aspect of the present invention, the control unit further comprises an auxiliary drive unit estimating unit, wherein an output of the auxiliary drive unit control unit is not interfered with an output of the main drive unit control unit. The disk device according to any one of claims 1 to 7, further comprising:

The present invention has the effect that interference between the main drive means and the auxiliary drive means can be eliminated.
As a result, as compared with the microactuator alone, the performance of the piggyback actuator is greatly degraded, and the position error suppression characteristic is also deteriorated. Can be solved. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

According to a ninth aspect of the present invention, there is provided a disk on which information data is recorded, a head section including a reproducing head for reproducing data recorded on the disk, and a head slider mounting the head section. A head part support mechanism for supporting the head slider and supporting the head in opposition to the disk; a main drive unit for driving the head part support mechanism to move the head; A method for controlling a disk drive, comprising: an auxiliary drive unit that moves the head unit by driving the head unit or the head slider; and a control unit that controls the main drive unit and the auxiliary drive unit, comprising: Detecting a current position of the head unit based on a reproduction signal of the head; and detecting or estimating a moving amount of the head unit by the main driving unit. A position detection step, a step of controlling the auxiliary driving unit based on information including a position error between a target position of the head unit and a current position of the head unit, and a detection or estimation in the relative position detection step. Controlling the main drive unit based on information including the amount of movement of the head unit. The present invention has an effect that a control method for a disk device in which a settling time is short and a residual position error during the settling is small can be obtained. Therefore,
As a result, there is an effect that a method of controlling a disk device having a high recording density can be obtained.

[0044]

Embodiments of the present invention will be described below with reference to the drawings. As an embodiment of the present invention, a magnetic disk device is exemplified, but the application of the present invention is not limited to a magnetic disk device, but is also applicable to various disk devices such as an optical disk and a magneto-optical disk. Further, in the embodiments, a magnetic disk device capable of recording and reproduction is exemplified, but the application of the present invention is not limited to a disk device capable of recording and reproduction, but is also applicable to a disk device capable of reproduction only.

Embodiment 1 A magnetic disk drive according to Embodiment 1 of the present invention will be described with reference to FIGS. [Description of FIG. 1] FIG. 1 is a schematic configuration diagram of a magnetic disk drive according to a first embodiment of the present invention. 1 is a magnetic disk, 2 is a composite magnetic head, 3 is a magnetic head slider, 4 is a head support mechanism, 5 is a rotating shaft of the head support mechanism, 6 is a control unit, and 5-1 is a main drive unit. A certain voice coil motor (VCM), 5-2 are auxiliary driving means,
6-1 is a head position detecting unit, 6-2 is a relative position detecting unit, 6-3-1 is a main driving unit control unit, 6-3-2 is an auxiliary driving unit control unit, and 6-4-1 is a main driving unit. Means drive,
6-4-2 is an auxiliary driving means driving unit. Reference numeral 6-2-1 denotes a main drive unit displacement amount detection unit that detects the displacement amount of the voice coil motor that is the main drive unit. 6-2-2 is
It is an auxiliary drive means displacement amount detection unit.

The composite magnetic head 2 includes a reproducing head which is a GMR head to which the magnetoresistance effect is applied, and a recording head which is an inductive magnetic head. The magnetic head slider 3 has the composite magnetic head 2 mounted thereon.
The head support mechanism 4 supports the magnetic head slider 3 and supports the composite magnetic head 2 facing the magnetic disk 1. The voice coil motor 5-1 drives the head support mechanism 4 around the rotation shaft 5 to move the composite magnetic head 2. The auxiliary driving means 5-2 drives the magnetic head slider 3 to move the composite magnetic head 2.

The head position detecting means 6-1 detects the current position of the composite magnetic head 2 (head section) based on the position information recorded on the magnetic disk 1 reproduced by the reproducing head of the composite magnetic head 2. Is detected and output. In the description of the present specification and the claims, "the target position of the head unit"
And "the current position of the head unit" means "the target position of the reproducing head" and "the current position of the reproducing head" when the reproducing head accesses the target position. In the case of accessing the print head, it means “the target position of the print head” and “the current position of the print head”. As described above, in the present specification and claims, the term "reproducing head" is a concept including a recording / reproducing head.

The recording head and the reproducing head are arranged at a fixed minute distance. When the recording head is moved to the target position, the target position of the reproducing head is determined at the temporary target position separated by the fixed minute distance from the target position of the recording head, and the reproducing head is moved from the current position to the temporary target. By actually moving the print head to the position, the print head may be moved to the true target value in some cases. In such a case, control is performed to move the current position of the recording head (the current position of the recording head that is a predetermined minute distance from the current position of the reproducing head) to the target position of the recording head. And the current position of the playhead
It can be considered that the control is to move to the temporary target position. Therefore, even in such a case, the case where all the other components of the present invention are provided is included in the technical scope of the present invention.

In the embodiment shown in FIG. 1, an encoder is used as a sensor for detecting the displacement of the voice coil motor. Specifically, the voice coil motor includes a rotatable small disk having a slit. The chassis 10 includes a plate having a similar slit and a photocoupler,
Is provided. The slit of the plate and the slit of the small disk cause interference, and the photocoupler can detect the displacement of the small disk.

The main drive means displacement amount detection unit 6-2-1 is
An output signal of the encoder is input, and based on the output signal, an amount of movement of the head unit by the main driving unit is detected and output. The output movement amount of the head unit by the main drive unit is input to the main drive unit control unit 6-3-1.
“Detection of the movement amount” means the distance moved by the head unit, but may be another position or movement amount (the target position of the head unit,
There are a current position of the head unit calculated based on a reproduction signal of the reproduction head, an amount of movement of the head unit by the auxiliary driving unit, and the like. ) Means to detect and output mutually operable values, and is not limited to, for example, measuring the actual distance (for example, 3150 μm) between two points on a disk. The unit of the moving amount does not need to be a general distance unit such as μm. It is not necessary that the value be proportional to the linear distance between two points on the disk. For example, the distance along the locus of the head unit driven by the main drive unit (drawing an arc around the rotation axis). May be a value proportional to. Alternatively, it may be a value proportional to the distance along the track of the disk. As a result, as described above, any value can be used as long as the value can be calculated mutually with another position or movement amount.

As will be described later with reference to FIG. 2, the piezoelectric elements 5-3-1 and 5-3-2 determine the displacement of the piezoelectric elements 5-2-1 and 5-2-2 as auxiliary driving means. , And outputs an electrical signal corresponding to the amount of displacement. The auxiliary driving means displacement amount detecting unit 6-2-2 includes a piezoelectric element 5-3-1.
And the output signals of 5-3-2 and the auxiliary driving means 5
-2 (composed of the piezoelectric elements 5-2-1 and 5-2-2) to calculate the amount of movement of the head by the auxiliary driving means 5-2, and output the amount of movement. I do. The meaning of “detection of the movement amount” is the same as the description of the main drive unit displacement amount detection unit 6-2-1 described above. The output movement amount of the head unit by the auxiliary driving unit is input to the auxiliary driving unit control unit 6-3-2.

The auxiliary driving means displacement amount detecting section 6-2-2 includes:
It is more preferable because the interference between the control of the main driving means and the auxiliary driving means can be further reduced, but this is not essential in the present invention. As in the related art, the amount of movement of the head unit by the auxiliary driving unit may be estimated from the magnitude of the control signal of the auxiliary driving unit. In FIG. 3 showing the details of the auxiliary driving unit control unit 6-3-2, the auxiliary driving unit displacement amount detecting unit 6-2-2 is not used, and the auxiliary driving unit A method of estimating the moving amount of the head unit by the driving means is adopted. In FIG. 3 of the first embodiment, the piezoelectric elements constituting the auxiliary driving unit 5-2 are:
Since the applied voltage and the amount of displacement have a fixed relationship, the applied voltage to the piezoelectric element and the relational expression between the amount of displacement of the piezoelectric element and the actual amount of displacement of the head (the amplification factor of the amount of displacement by the microactuator mechanism) ), The moving amount of the head unit is estimated.

As described above, the amount of movement of the head unit by the main drive unit output from the main drive unit displacement amount detection unit 6-2-1 is input to the main drive unit control unit 6-3-1. Further, the auxiliary driving unit control unit 6-3-2 calculates a value obtained by subtracting the amount of movement of the head by the auxiliary driving unit from the reading position of the reproducing head (the position of the head when there is no auxiliary driving unit) (FIG. 3-6-3-2B), the value is transmitted to the main drive means control section 6-3-1. The main drive unit control unit 6-3-1 calculates a control amount of the main drive unit (voice coil motor) and outputs a control signal. Detail is,
This will be described in the description of FIG. Main driving means driving unit 6
4-1 is a so-called drive stage, which drives the voice coil motor according to the input control signal.

The auxiliary drive means control section 6-3-2 is a target position of the composite magnetic head (not shown in FIG. 1).
And the current position of the composite magnetic head 2 (head portion) sent from the head position detecting means 6-1 is compared.
A control signal is output so as to reduce the position error. Details will be described in the description of FIG. The auxiliary driving unit driving unit 6-4-2 drives the auxiliary driving unit 5-2 in a so-called drive stage according to the input control signal.

[Explanation of FIG. 2] FIG. 2 shows a configuration diagram of a microactuator serving as auxiliary driving means. 5-2-1
And 5-2-2 denote piezoelectric elements which are drive units (auxiliary drive units) of the microactuator. Each of them is used by push-pull, and drives the magnetic head slider 3, whereby the composite magnetic head 3 mounted on the magnetic head slider 3 is displaced. In the upper diagram of FIG. 2, the composite magnetic head moves up and down on the paper by the piezoelectric element. In the lower diagram of FIG. 2, it moves in a direction perpendicular to the paper surface. Also,
Piezoelectric elements 5-2-1 and 5-2-2 serving as auxiliary driving means
The piezoelectric elements 5-3-1 and 5-3-2 adhered to are auxiliary displacement detecting units for detecting the displacement of the actuator as electric signals by piezoelectric conversion.

[Description of FIG. 3] FIG. 3 is a block diagram of the servo system of the disk device shown in FIG. An operation sequence of the servo system in the magnetic disk device of the embodiment will be described. Position information (referred to as a servo pattern) written on the magnetic disk 1 is detected by the reproducing head of the composite magnetic head 2. Then, the head position detecting means 6
-1 detects the track position and the inter-track position of the magnetic head from the detection signal. Head position detecting means 6-
1 outputs a signal indicating the current position of the head unit.

From the left end of FIG. 3 (in FIG.
The target position of the head unit is input.
The auxiliary driving means control unit 6-3-2 includes a subtractor 6-3-2A.
, An auxiliary driving means calculating unit 6-3-2C, an auxiliary driving means estimating means 6-3-2E, a subtractor 6-3-2B, and an adder 6-3-2D.

The adder 6-3-2D calculates the current position of the head section (output of the head position detecting means 6-1) and the estimated relative movement amount of the auxiliary driving means (the head position detecting means 6-1 controls the head position). (The output of the auxiliary driving means estimating means 6-3-2E) after the reading of the current position of the head section, and outputs the latest current position of the head section as the addition result. . When the head position detecting means 6-1 newly reads the position information, at that time the estimated relative movement amount of the auxiliary driving means inputted to the adder 6-3-2D (the auxiliary driving means estimating means 6-3-3) 2E) is reset to zero, and the output (the latest current position of the head) of the adder 6-3-2D at that time is the position information newly read by the head position detecting means 6-1. The position is based on Adder 6
-3-2D adds the estimated relative movement amount of the auxiliary driving means starting from that time to the position of the head section read by the head position detecting means 6-1 and sets the addition result to the current position of the head section And output. Thereafter, when the head position detecting means 6-1 newly reads the position information again, at that time,
The estimated relative movement amount of the auxiliary driving means (output of the auxiliary driving means estimating means 6-3-2E) input to the adder 6-3-2D is reset to zero, and the adder 6-3 at that time is reset.
The output of -2D (the current position of the head unit) is a position based on the position information newly read by the head position detecting unit 6-1. Thus, the adder 6-3-2D
Shows the details of the movement of the head section from the time when the head position detection means 6-1 reads the position information to the time when the next position information is read, and the output of the auxiliary drive means estimation means 6-3-2E. Use and output.

The subtractor 6-3-2A calculates the latest current position of the head unit (adder 6-3-3) from the target position of the head unit.
2D output) and subtracting the resulting position error between the target head position and the latest current position of the head section.
Output. The position error is calculated by the auxiliary driving means calculating unit 6-3.
-2C. Auxiliary drive means calculation unit 6-3-2
C calculates so as to reduce the position error, and outputs a control signal. The control signal is transmitted to the auxiliary driving means driving section 6-4.
-2 and the auxiliary driving means estimating means 6-3-2E.

The auxiliary driving means estimating means 6-3-2E constitutes an observer. That is, the auxiliary driving unit estimating unit 6-3-2E is a virtual model (estimated model) of the auxiliary driving unit 5-2 in mathematical expressions. Auxiliary driving means estimating means 6-
3-2E is the latest current position of the head unit (adder 6-
3-2D output) and a control signal (auxiliary drive means calculation unit 6)
-3-2C), and calculates and outputs an estimated value of the moving amount of the head unit by the auxiliary driving unit 5-2, a speed feedback signal, and the like. The estimated value of the moving amount of the head unit by the auxiliary driving unit 5-2 is input to the adder 6-3-2D and the subtractor 6-3-2B. Adder 6-3-
The 2D processing has been described above. The speed feedback signal and the like are input to the auxiliary driving means calculation unit 6-3-2C.

As described above, FIG. 3 shows an embodiment in which the auxiliary drive means displacement amount detecting section 6-2-2 is not used. Instead of actually detecting the moving amount (displacement amount) of the head unit by the auxiliary driving unit, the auxiliary driving unit estimating unit 6-3-2E uses
The moving amount is estimated using a mathematical model. In another embodiment having the microactuator having the configuration shown in FIG. 2 and the auxiliary driving unit displacement amount detecting unit 6-2-2, the auxiliary driving unit displacement amount detecting unit 6-2-2 measures and detects The movement amount of the head unit by the auxiliary driving unit 5-2 is output.
The detected value of the moving amount of the head unit by the auxiliary driving unit 5-2 is input to the adder 6-3-2D and the subtractor 6-3-2B in FIG. That is, in the embodiment of FIG. 3, the output of the auxiliary driving means estimation means 6-3-2E is obtained.
The estimated value of the moving amount of the head unit by the auxiliary driving unit 5-2 is replaced with the estimated value. The role of the detected movement amount of the auxiliary drive unit and the estimated movement amount of the auxiliary drive unit in the control system are the same.

More specifically, the auxiliary driving means estimating means 6-3
-2E has a virtual model (estimated model) on the mathematical expression of the auxiliary driving means 5-2, and the virtual auxiliary driving means 5-2
Is driven on a mathematical expression, and as a result, a virtual displacement (estimated moving amount) of the auxiliary driving means is obtained. The displacement of the head unit by the microactuator is determined from the displacement of the virtual auxiliary driving means. Auxiliary driving means estimating means 6-3-
2E also incorporates a conversion coefficient (amplification factor) on this mechanism. Further, the current position of the head unit is included in the calculation, and the amount of movement of the head unit by the auxiliary driving means is obtained. Since the moving direction of the head unit with respect to the disk changes depending on the current position of the head unit, it is necessary to consider the current position of the head unit in order to determine the amount of movement with respect to the disk. In the present embodiment, both the moving amount of the head unit by the main driving unit and the moving amount of the head unit by the auxiliary driving unit are all calculated so that the values such as the current position of the head unit detected by the reproducing head can be calculated. , And the movement and position of the head with respect to the disk.

From the current position of the head unit (the output of the head position detecting unit 6-1), the estimated value of the moving amount of the head unit by the auxiliary driving unit (the output of the auxiliary driving unit estimating unit 6-3-2E) is calculated as follows. The subtraction is performed (subtractor 6-3-2B), and the subtraction result is input to the adder 6-3-1D. In Conventional Example 2, at the current position of the head portion read by the reproducing head,
After the read head has read the current position, the latest travel position of the head unit is estimated by adding the distance that the head unit has moved by the microactuator thereafter (in FIG. 3, the adder 6-3). −2D output). The latest current position of the head section is directly calculated by the subtracter 6-3-.
1A and the main driving means estimating means 6-3-1E.

On the other hand, the subtractor 6-3- in the present embodiment is used.
2B subtracts the estimated movement amount of the microactuator from the current position of the head portion read by the reproducing head. When the head position detecting means 6-1 newly reads the position information and outputs the current position of the head unit, at that time,
The subtractor 6-3-2B calculates an estimated relative movement amount of the auxiliary drive unit (the auxiliary drive unit estimation unit 6-3) from the current position of the head unit (output of the head position detection unit 6-1). -2E) and outputs the result of the subtraction. The subtractor 6-3-2B performs an operation (subtraction) only when the head position detecting unit 6-1 newly reads the position information and outputs the current position of the head unit, and outputs the result. In the subtractor 6-3-2B, the estimated relative movement amount of the auxiliary driving means is not reset. The subtracted value is the current position of the head unit when there is no microactuator. If you change the expression,
This is the position of the center point for driving the microactuator.
In the present invention, the main driving unit control unit controls the main driving unit such that the center point of driving of the microactuator matches the target position. That is, the main driving unit estimating unit 6-3-1E inputs the center point of the driving range of the microactuator and controls the main driving unit so that the current position of the head unit comes to the center point. This means that the main drive unit is controlled independently of the amount of movement of the head unit by the microactuator (without interference). As described above, the subtractor 6-3
-2B inputs the same signal as the arithmetic unit (corresponding to the same one as the adder 6-3-2D) of the conventional example 2. However, the timing and content of the operation, the physical significance of the operation result, etc. , Completely different.

As described above, the auxiliary driving means calculating section 6-3-2C calculates the position error between the target head position and the current latest position of the head section (the output of the subtractor 6-3-2A), Speed feedback signal, etc. (auxiliary driving means estimating means 6-3
-2E output), and controls the auxiliary driving means so that the position error becomes zero (actually, a residual error remains). The control signal output from the auxiliary drive means calculation unit 6-3-2C is input to the auxiliary drive means drive unit 6-4-2, and the auxiliary drive means drive unit 6-4-2 outputs the control signal to the auxiliary drive means 5-2 ( The piezoelectric elements 5-2-1 and 5-2-2) are driven. The output of the auxiliary driving unit 5-2 is output to the auxiliary driving unit 5-2.
Is the actual amount of movement of the head.

Similarly, in the control section of the main drive means, the target position of the head section is input from the left end of FIG. 3 (left side of the subtractor 6-3-1A). Main drive means controller 6
3-1 is a subtractor 6-3-1A, a main drive unit operation unit 6-3-1C, and a main drive unit estimation unit 6-3-1E.
And an adder 6-3-1D.

The adder 6-3-1D calculates the current position of the head unit when there is no microactuator (the subtractor 6-3-1D).
3-2B) and the estimated relative movement amount of the main drive means (the relative movement amount after the head position detection means 6-1 reads the current position of the head unit. The auxiliary drive means estimation means 6-3) -2E output), and outputs the addition result, that is, the latest current position of the head unit when there is no microactuator. As described above, when the head position detecting unit 6-1 newly reads the position information, the subtractor 6-3-2B outputs the current position of the head unit when there is no microactuator at that time. At this time,
The adder 6-3-1D calculates the current position of the head unit in the absence of the microactuator (subtractor 6-3-2B).
Of the main drive means (the output of the main drive means displacement amount detection unit 6-2-1) at that time.
Reset) to zero. Adder 6 at that time
The output of -3-1D is output by the subtractor 6-3-2B,
This is the current position of the head unit without the microactuator. The adder 6-3-1D includes a subtractor 6-3.
-2B, the relative movement amount of the main driving means (main driving means displacement detection, starting from the time when the subtractor 6-3-2B outputs the current position of the head unit when there is no microactuator) Output of the unit 6-2-1)
The addition result (the latest current position of the head unit when there is no microactuator) is output. Thereafter, the head position detecting means 6-1 reads the new position information again, and the subtractor 6-3-2B outputs the current position of the head unit in the absence of the microactuator. The relative movement amount of the main drive unit (output of the main drive unit displacement amount detection unit 6-2-1) input to the 3-3-1D is reset to zero, and the output of the adder 6-3-1D at that time is reset. Is the current position of the head unit when there is no micro-actuator, output by the subtractor 6-3-2B. In this way, the adder 6-3-1D sets the head position detecting means 6-1 to newly read the position information,
3-2B outputs the current position of the head unit when there is no microactuator, and then the subtracter 6
The details of the movement of the head unit until the current position of the head unit in the absence of the micro actuator is output by the main driving unit displacement amount detection unit 6-2-3.
1 is output using the output.

From the target position of the head, the subtractor 6-3-1A calculates the latest current position of the head (the output of the adder 6-3-1D) when there is no microactuator.
The subtraction (subtractor 6-3-1A) is subtracted, and the error signal of the main drive unit (the output of the subtractor 6-3-1A) as a result of the subtraction is input to the main drive unit calculation unit 6-3-1C. You. The main drive means calculation unit 6-3-1C performs calculation to reduce the position error and outputs a control signal. The control signal is input to the main driving unit driving unit 6-4-1 and the main driving unit estimating unit 6-3-1E.

The main driving means estimating means 6-3-1E constitutes an observer. That is, the main driving unit estimating unit 6-3-1E is a virtual model (estimated model) of the main driving unit 5-1 in the mathematical expression. Main driving means estimating means 6
3-1E is the latest current position of the head unit when there is no microactuator (in other words, the latest current position of the center point of the driving range of the microactuator).
An input of the adder 6-3-1D) and a control signal (an output of the main drive means calculation unit 6-3-1C) are input, and a speed feedback signal and the like are calculated and output. The speed feedback signal and the like are input to the main drive unit calculation unit 6-3-1C.

In another embodiment of the present invention which does not use the main drive means displacement amount detecting unit 6-2-1, the main drive means estimating means 6-3-1E includes a speed feedback signal and the like. 5-1 is calculated and output. The estimated value of the moving amount of the head unit by the main driving unit 5-1 is sent to an adder 6-3-1D.
(The output is replaced with the output of the main drive unit displacement amount detection unit 6-2-1.) The processing of the adder 6-3-1D has been described above.

Specifically, the main driving means estimating means 6-3
-1E has a virtual model (estimated model) on the mathematical expression of the main driving unit 5-1 and the virtual main driving unit 5-1.
Is driven on a mathematical expression, and as a result, a virtual displacement (estimated moving amount) of the main driving means is obtained. From the virtual displacement of the main driving unit, the displacement of the head unit by the main driving unit (voice coil motor) is obtained. The main driving means estimating means 6-3-1E calculates the conversion coefficient (amplification rate) on this mechanism.
It also has a built-in. Further, the current position of the head unit is included in the calculation, and the amount of movement of the head unit by the main driving unit is obtained. Since the moving direction of the head unit with respect to the disk changes depending on the current position of the head unit, it is necessary to consider the current position of the head unit in order to determine the amount of movement with respect to the disk. In the present embodiment, the amount of movement of the head unit by the main drive unit is converted into the movement and position of the head unit with respect to the disk so that it can be calculated with a value such as the current position of the head unit detected by the reproducing head. I have. When the main driving unit displacement amount detecting unit 6-2-1 is not used, the main driving unit estimating unit 6-3-1E outputs the estimated moving amount of the head unit. A feedback signal based on a differential value (speed) of the estimated moving amount of the head unit regardless of the presence or absence of the main driving unit estimating unit 6-3-1E;
Further, a disturbance amount feedforward gain signal based on the estimated movement amount of the head unit is output.

As described above, the main driving means calculating section 6-3-1C calculates the latest current position of the head section in the absence of the microactuator from the target position of the head section (by the adder 6-3-1D). The position error (subtractor 6-3-1A) obtained by subtracting the output is input, and the main driving unit is controlled so that the position error is reduced. The control signal output from the main drive means calculation unit 6-3-1C is input to the main drive means drive unit 6-4-1, and the main drive means drive unit 6-4-1 is output.
1 drives the main drive means 5-1 (voice coil motor). The output of the main driving unit 5-1 is
-1 is the actual amount of movement of the head. The main drive unit displacement amount detection unit 6-2-1 detects the amount of movement of the head unit by the main drive unit.

The adder 5-3 outputs the sum of the amount of movement of the head unit by the main drive unit and the amount of movement of the head unit by the auxiliary drive unit (ie, the actual amount of movement of the head unit).

[Explanation of FIG. 16] FIG. 16 shows a main driving means calculating unit 6-3-1C and a main driving means estimating means 6-3-3.
1E shows a detailed block diagram. Reference numeral 6-5 denotes an output signal of the relative position calculator 6-5 of FIG. 3 (or FIG. 9 of a second embodiment described later).

The main driving means operation unit 6-3-1C has a position error feedback amplifier, a speed feedback amplifier, and a disturbance amount feedforward amplifier.
The position error feedback amplifier subtracts the latest current position (output of the adder 6-3-1D) of the head unit when there is no microactuator from the target position of the head unit, and obtains a position error (subtracter 6-3). -1A) is amplified by a constant Kp, and a value proportional to the error signal is output.
The speed feedback amplifier comprises a main driving means estimating means 6
-3-1E amplifies the estimated speed (differential position error) output by a constant Kv and outputs a value proportional to the estimated speed. The disturbance feedforward amplifier is 6-3-3.
The estimated disturbance output by 1E is amplified by a constant Kd, and a value proportional to the estimated disturbance is output.

The main driving means calculating section 6-3-1C feeds back the position error and the head speed estimated by the main driving means estimating means 6-3-1E, and disturbs the head (force disturbance, position disturbance). The control amount is derived by feed-forwarding the (disturbance) amount. The main driving unit estimating unit 6-3-1E is an estimated speed that is a result of driving a virtual model (estimated model) of the main driving unit by a control signal that is an output signal of the main driving unit operation unit 6-3-1C. Component (head speed based on virtual model of main driving means)
Is estimated, and the result is fed back to the speed feedback amplifier (gain Kv) of the main driving means operation unit 6-3-1C as the estimated speed.

A subtractor 6-3-1A for calculating a position error
, The amount of movement of the head unit by the auxiliary driving means is removed. Therefore, the output position error is not affected by the driving of the auxiliary driving unit. In the conventional example, each of the main drive unit and the auxiliary spike drive unit tried to individually move the head unit to the target position. For example, when the target position is reached by moving another 5 μm, in the worst case, the main driving unit and the auxiliary driving unit move the head unit by 5 μm, and as a result, the head unit is moved by 10 μm.
m in some cases. According to the present invention, the auxiliary driving means having a high response speed is controlled so as to move the head portion to the target position, but the main driving means having a low response speed is the latest current driving of the head portion in the absence of the microactuator. (In other words, the latest current position of the center point of the drive range of the microactuator. Adder 6
−3-1D output) to the target position.

As a result, the control of the main driving means is not influenced by the movement of the auxiliary driving means. To be swung by the movement of the auxiliary drive means, due to the fast movement of the auxiliary drive means, the main drive means overshoots the target, or accelerates or decelerates to compensate for the movement of the auxiliary drive means, As a result, it means that vibration is caused.
Since the response speed of the auxiliary driving means is fast, as in the conventional example,
When the movement amount of the entire head unit including the movement amount of the head unit by the auxiliary driving unit is fed back to the estimation model of the main driving unit, the control of the main driving unit is greatly affected by the output of the auxiliary driving unit. As described above, by inputting the position of the center point of the driving range of the microactuator to the main driving unit estimating unit 6-3-1E, it is possible to eliminate the influence of the movement amount of the head unit by the auxiliary driving unit ( Interference is eliminated.), And a significant improvement in control performance can be achieved.

When the position of the head is calculated including the amount of movement by the auxiliary driving means as in the prior art, in particular, the moving speed of the head portion is determined by the speed component based on the driving of the main driving means,
It could not be divided into a speed component based on driving of the auxiliary driving means. Since the position control for moving the head unit to the target position is a control of a vibration system (quadratic equation), optimal damping of the velocity component is a major point for realizing a high convergence speed. However, when it is not possible to distinguish whether the speed component is a component based on the main driving means or a component based on the auxiliary driving means, as in the conventional example, the speed component of the head portion is virtually changed to the main driving means. The control means and the auxiliary drive means are appropriately allocated to the control means and fed back at a fixed rate. Therefore, when the speed component by the auxiliary driving unit is actually larger than the allocation of the feedback system, the braking of the driving by the auxiliary driving unit is not effective, and the head moves beyond the target position and the head unit vibrates. is what happened. On the other hand, if the speed component of the auxiliary driving means is actually smaller than the allocation of the feedback system, the braking of the driving by the auxiliary driving means is too effective, and the moving speed of the head part is almost lost, so it is difficult to achieve the target. The position cannot be reached. Similarly, with respect to the main driving means, the head part vibrates or the braking is too effective. Here, since the direction and speed of the movement by the main drive unit and the direction and speed of the movement by the auxiliary drive unit are separate, insufficient braking (excessive braking) of the main drive unit causes excessive braking (braking) of the auxiliary drive unit. Insufficiency) cannot make up for it. In the prior art, in effect, insufficient braking (excessive braking) of the main driving means is compensated for by excessive braking (insufficient braking) of the auxiliary driving means, and as a result, good results cannot be obtained.

According to the present invention, the amount of movement by the main driving means
By independently detecting or estimating the movement amount of the auxiliary driving means, the movement amount and speed of the head unit based on the main driving means and the movement amount and speed of the head unit based on the auxiliary driving means are independently determined. Therefore, the feedback amount can be optimally realized for each of the main drive unit and the auxiliary drive unit.

The adder 6-3-1A and the main driving means estimating means 6-3-1E can improve the control performance of the main driving means by inputting the moving amount of the head by the main driving means. I can do it. The adder 6-3-1A inputs the latest position of the center point of the microactuator drive range obtained by adding the movement amount of the head unit by the main drive means to the position of the center point of the microactuator drive range, Outputs an error from the target position. Main drive means calculation unit 6
-3-1C performs an operation to reduce the error and outputs the operation result. Similarly, the main driving means estimating means 6-
3-1E inputs the latest position of the center point of the drive range of the microactuator obtained by adding the movement amount of the head unit by the main drive means to the position of the center point of the drive range of the microactuator, and Then, the speed of the head unit and the like are output. Accordingly, the calculation result takes into account the fine movement amount of the head unit by the main driving unit, and the estimation is close to the actual operation of the head unit.
Conventionally, the moving amount of the head unit by the auxiliary driving unit and the moving amount of the head unit by the main driving unit have not been distinguished from each other. Even taking into account the relative movement of the head by the main drive means, it did not lead to any improvement in control performance. According to the present invention, the influence of the moving amount of the head unit by the auxiliary driving unit can be eliminated, and by taking into account the relative moving amount of the head unit by the slow main driving unit, the speed of the main driving unit can be increased. High-precision control is realized.

Further, according to the present invention, it is realized that the auxiliary driving means is driven around the applied voltage zero.
In the conventional example, if the head reaches the target position,
Since the main drive unit and the auxiliary drive unit do not move any more, the state in which the auxiliary drive unit (for example, a piezoelectric element) generates a certain large displacement sometimes continues. However, for example, when the piezoelectric element continues to be in a state of constant large displacement, adverse effects such as an increase in hysteresis appear, so that the position of the center point of the driving range of the microactuator is preferably set to an auxiliary driving unit. This is the point where the amount of displacement is zero. In addition, it is preferable that absorption of fine and quick fluctuations of the head portion in a state where the head is on-track is performed by an auxiliary driving means having a fast response. However, when the auxiliary drive unit reaches the target position in a state where the auxiliary drive unit is biased to one side (for example, a state in which the auxiliary drive unit is fully displaced to the left end), the auxiliary drive unit can absorb the rightward swing of the head unit. Cannot respond to shaking to the left. According to the present invention, in order to move the position of the center point of the drive range of the microactuator to the target position, the position error is converged to zero (actually, a certain residual error remains), so that the auxiliary driving means is driven. The DC deviation of the drive amount can be eliminated, and the drive amplitude in a steady state can be reduced. Also, the auxiliary driving means is
It has an equal pull-in range on the left and right, and can cope with left and right swings of the head. When a piezoelectric element is used as the auxiliary driving means, a constant displacement may remain in the piezoelectric element due to hysteresis even when the applied voltage to the piezoelectric element is set to zero. However, since such hysteresis does not affect the essence of the control of the disk drive according to the present invention, the position of the center point of the drive range of the microactuator is set to the target position with a certain amount of displacement remaining by the auxiliary drive means. The case where control is performed so as to approach is also included in the technical scope of the present invention.

The main driving means estimating means 6-3-1E
Outputs the disturbance component stored therein, and feeds it forward to the disturbance amount feedforward amplifier (gain Kd) of the main driving means operation unit 6-3-1C. The main driving means estimating means 6-3-1E has a storage device for independently storing a disturbance component synchronized with the rotation cycle of the disk and a disturbance component asynchronous with the rotation cycle. A specific position on the disk of the disk device may have a specific disturbance. Although the control performance of the disk device is deteriorated due to the disturbance, the disturbance at the specific point is learned, the disturbance information is stored, and the disturbance information at the specific point is predicted and taken into the control (specifically, the specific point). For example, a method is known in which a control unit feeds forward disturbance information.)

However, in order to store all the disturbances unique to each position on the disk, a very large-capacity storage device is required. On the other hand, the disturbance component of the disk device generally occupies a large weight with the disturbance component synchronized with the rotation cycle. In addition, a disturbance component that is asynchronous with the rotation cycle often occurs only at a specific point. Therefore, according to the present invention, a disturbance component synchronized with the rotation cycle of the disk is stored using the angle (0 to 360 degrees) on the disk as a parameter. For disturbance components that are asynchronous to the other rotation cycles, unique position information and the magnitude of the disturbance components are individually stored. As a result, the capacity of the storage device for storing the disturbance information can be reduced.

The influence of the disturbance on the control of the disturbance component synchronized with the rotation cycle often differs depending on the position of the head (distance from the center of the disk). In such a case, for example, the control unit feeds a value obtained by multiplying the disturbance information stored in the storage device by the distance from the center of the disk to the main drive unit calculation unit (or the auxiliary drive unit calculation unit). As described above, by compressing and storing the disturbance component synchronized with the rotation period into disturbance information having a small capacity, the storage capacity of the necessary storage device can be reduced in the control device that learns and stores the disturbance component. Can be done.

[Explanation of FIG. 17] FIG. 17 shows an auxiliary driving means calculating section 6-3-2C and an auxiliary driving means estimating means 6-3-3.
2E shows a detailed block diagram.

The auxiliary driving means operation section 6-3-2C has a position error feedback amplifier, a speed feedback amplifier, and a disturbance amount feedforward amplifier.
The position error feedback amplifier provides an error signal (subtractor 6-3-2A) between the target position of the head unit and the current latest position (measured position or estimated position; output of the adder 6-3-2D) of the head unit. Is amplified by a constant Kp, and a value proportional to the error signal is output. The speed feedback amplifier amplifies the estimated speed output from the auxiliary driving means estimating means 6-3-2E with a constant Kv, and outputs a value proportional to the estimated speed. The disturbance amount feedforward amplifier amplifies the estimated disturbance output from the auxiliary driving means estimating means 6-3-2E with a constant Kd, and outputs a value proportional to the estimated disturbance.

The auxiliary driving means calculating section 6-3-2C feeds back the error signal (output of the subtractor 6-3-2A) and the head speed estimated by the auxiliary driving means estimating means 6-3-2E. Then, the control amount is derived by feed-forwarding the amount of disturbance (force disturbance, position disturbance) applied to the head.

The auxiliary driving means estimating means 6-3-2E is an estimation model (virtual model) of the auxiliary driving means. The adder 6-3-2D includes a current position of the head unit (output of the head position detecting unit 6-1) and an auxiliary driving unit estimating unit 6-3.
-2E is added to the estimated amount of movement of the head unit by the auxiliary driving means (see FIG. 3). The current latest position of the head unit, which is the result of the addition, is input to the estimation model of the auxiliary driving unit. The auxiliary driving unit estimating unit 6-3-2E outputs the current latest position of the head unit (the output of the adder 6-3-2D) and the control signal (the output of the auxiliary driving unit calculating unit 6-3-2C). It inputs and estimates the current latest position of the head unit and the estimated speed component of the head unit (the speed of the head unit based on the virtual model of the auxiliary drive unit), and uses the result as an estimated speed to calculate the auxiliary drive unit arithmetic unit 6 -3-2 Feed back to the speed feedback amplifier (gain Kv).

Further, a disturbance component stored inside is output,
It feeds forward to the disturbance amount feedforward amplifier (gain Kd) of the auxiliary driving means calculation unit 6-3-2C. The auxiliary driving unit estimating unit 6-3-2E has a storage device that independently stores a disturbance component synchronized with the rotation cycle of the disk and a disturbance component asynchronous with the rotation cycle. The disturbance component stored in the auxiliary driving unit estimating unit 6-3-2E is the same as the disturbance component stored in the main driving unit estimating unit 6-3-2E.

[Explanation of FIGS. 4 to 7] FIG. 4 to FIG.
4 shows simulation results of response characteristics according to the embodiment of the present invention. FIG. 4 shows the step response. The settling time for the head section to converge to the target position is just over 1 ms. The target level is 1. The unit of time on the horizontal axis is seconds (S). FIG. 5 shows the frequency characteristics of the closed loop.
The upper diagram is a gain diagram, and the lower diagram is a phase diagram. FIG. 6 shows a transition of the position error signal when a disturbance is applied. The position error signal indicates a position error when four types of position error factors are input to the servo system. The vertical axis represents the position error (bit), and the horizontal axis represents time (S). A position error of 50 bits corresponds to about 10% of the track pitch. FIG. 7 shows a histogram of the residual position error during settling. The three sigma of position error is
0.0455 μm. The histogram is the frequency distribution of the position error in FIG. The vertical axis indicates frequency, and the horizontal axis indicates position error (bit number).

Hereinafter, conditions of the simulation experiment will be described. Track pitch: 0.56 μm Spindle motor rotation speed: 5400 rpm Servo sector number: 223 Servo sampling frequency: 20 kHz

Main actuator inertia moment: 3.25 × 10 ⁻⁶ kgm ² Main actuator resonance: w1 = 100 Hz / ζ = 0.9 w2 = 2 kHz / ζ = 0.02 Main actuator arm length: 0.0521 m

VCM force constant: 0.0564 N / A VCM driver IC characteristics: 0.8 A / 2 ¹⁴ bits Main actuator controller design pole: w1 = 500 Hz / ζ = 0.7 Main actuator observer design pole: w1 = 1 kHz / ζ = 0.7 w2 = 1.5kHz

Microactuator characteristics: 13 nm / V Microactuator driver IC characteristics: 30 V / 2 ¹⁴ bits Microactuator mass: 1 mg Microactuator resonance: w1 = 500 Hz / ζ = 0.05 w2 = 8 kHz / ζ = 0.05 Microactuator Controller design pole: w1 = 2 kHz / ζ = 0.7 Micro actuator observer Design pole: w1 = 4 kHz / ζ = 0.7 w2 = 6 kHz

A / D conversion bit number: 8 bits D / A conversion bit number: 14 bits Position detection characteristics: 512 bits / track pitch Input disturbance for position error evaluation 1: Position disturbance component of disk vibration (rotation synchronization component) 2: Disk vibration (Rotation asynchronous component) position disturbance component 3: Position disturbance component of electrical noise 4: Force disturbance component

Since the track pitch of a disk device for high-density recording is very narrow, the first relative position detecting means for detecting the amount of movement of the head unit by the main driving means (voice coil motor) (for example, in the first embodiment, , Encoder.) The detection accuracy is low. For this reason, it has conventionally been considered that in a disk device for high-density recording, a relative position detecting means such as an encoder is not useful for speeding up control or increasing accuracy. Therefore, in particular, the piggyback actuator for pursuing higher speed and higher accuracy and the low-accuracy encoder for the voice coil were conventionally considered to be used for completely different purposes. . Therefore, in a conventional high-density disk device, the voice coil motor generally does not include an encoder.

The inventor of the present invention has sought to find the cause of the deterioration of the performance of the conventional piggyback actuator as compared with the performance of the microactuator alone. As a result, the cause of the deterioration of the performance of the conventional piggyback actuator is that the control of the main drive unit and the control of the auxiliary drive unit not only have a synergistic effect with each other, but in fact,
On the contrary, they discovered that they interfered with each other. That is,
As described above, the main driving means is swung to the auxiliary driving means,
As a result, a phenomenon occurs in which the auxiliary driving means is swung to the main driving means.

Therefore, the present invention distinguishes between the amount of movement of the head unit by the main driving unit and the amount of movement of the head unit by the auxiliary driving unit, so that the control of the main driving unit can be controlled by the control of the auxiliary driving unit. To prevent interference. As a result, the performance of the piggyback actuator approaching the performance of the microactuator alone could be achieved. Further, by separating the control of the main drive unit and the control of the auxiliary drive unit, the relative movement amount of the head unit by the main drive unit is detected or estimated, and the head detected by the detected or estimated main drive unit is used. By inputting the relative movement amount of the unit into the control of the main driving means, it is possible to improve the control performance of the main driving means and, consequently, the control performance of the entire piggyback actuator. It is also desirable that the control of the auxiliary drive is not interfered with by the control of the main drive.
In this embodiment, since the response of the main driving unit is slower than the response of the auxiliary driving unit, the control of the auxiliary driving unit is not significantly affected by the control of the main driving unit. Therefore, the control unit of the auxiliary driving unit is not directly prevented from being interfered by the control unit of the main driving unit. However, by preventing the main driving unit from being swung by the auxiliary driving unit, the auxiliary driving unit is also prevented from being swung by the main driving unit. However, when the response of the main drive unit has a speed relatively close to the response of the auxiliary drive unit, the control of the auxiliary drive unit is prevented from being interfered by the control of the main drive unit, thereby improving the performance of the control system. Is obtained.

For quantitative comparison, the histograms of the residual position errors at the time of settling are compared. As described above, the three sigma of the position error by the control method of Conventional Example 1 or Conventional Example 3 is 0.0952 μm (FIG. 37), and the three sigma of the position error by the control method of Conventional Example 2 is 0.0628 μm.
(FIG. 41). Although the accuracy of the voice coil encoder is low, the three sigma of the position error of the first embodiment of the present invention is 0.0455 μm (FIG. 7). This position error not only exceeds the performance of the conventional control method, but also approaches 0.0415 μm (FIG. 33), which is 3 sigma of the position error of the microactuator alone. In the embodiment of the present invention, the settling time of the step response is set at slightly more than 1 ms (FIG. 4), which is greatly improved from the settling time of 4 ms (FIG. 34) according to the control method of Conventional Example 1 or Conventional Example 3. Therefore, it is at the same level as compared with the control method of the conventional example 2.

As a result, the performance of the conventional piggyback actuator is greatly deteriorated as compared with the performance of the microactuator alone because the main driving means and the auxiliary driving means interfere with each other. That is, the analysis of the inventor of the present invention proved to be correct. Further, in the case where the performance of the microactuator alone is improved in the future, the control performance of the entire disk device is not likely to be much improved by the conventional control method due to mutual interference between the main drive unit and the auxiliary drive unit. In the disk device, it is considered that the improvement of the performance of the microactuator alone leads directly to the improvement of the control performance of the entire disk device.

As described above, since the main driving means is controlled so that the position of the head portion when there is no auxiliary driving means is close to the target position, the piezoelectric element or the like as the auxiliary driving means is at the center of the operating range. Controlled and driven nearby. As a result, the effects of hysteresis and aging due to excessive driving of the piezoelectric element can be suppressed. According to this embodiment, the positioning error of the head section can be reduced at high speed and with high accuracy by the piggyback servo system.

In the present invention, the purpose of providing the first relative position detecting means (the encoder in the first embodiment) for detecting or estimating the moving amount of the head unit by the main driving means (voice coil motor) is to use the main driving means alone. It does not aim to improve the control performance (high speed and high accuracy, etc.) of the. In the present invention, the purpose of providing the first relative position detecting means is to separate and identify the moving amount of the head unit by the main driving unit and the moving amount of the head unit by the auxiliary driving unit from the moving amount of the head unit. It is. Thus, the control of the main drive unit and the control of the auxiliary drive unit are mutually non-interfering.

"No interference" according to claim 7
The meaning of the term is that the influence of the amount of movement of the head unit by the auxiliary driving unit, the speed of the head unit by the auxiliary driving unit, etc. on the control signal of the main driving unit is excluded. Similarly, the meaning of the term “not interfered” in claim 8 means that the amount of movement of the head unit by the main driving unit, the speed of the head unit by the main driving unit, and the like.
That is, the effect on the control signal of the auxiliary driving means is eliminated.

The term “not interfered” means that interference is eliminated in the concept of the present invention. In an actual product that measures and estimates a non-ideal movement amount, interference cannot be completely eliminated. However, it should be noted that even in the case of measurement and estimation of a non-ideal movement amount, as described above, a significant improvement in performance has been obtained as compared with the related art. Therefore, an invention that satisfies the claims even if interference actually remains is included in the technical scope of the present invention.

In a conventional disk drive using a piggyback actuator, the entire moving amount is not clearly discriminated as to whether it is the moving amount of the head by the main driving means or the moving amount of the head by the auxiliary driving means. In addition, since the control input signal is taken in, the control of the main drive unit is controlled by the driving of the head unit by the auxiliary drive unit, and the control of the auxiliary drive unit is controlled by the drive of the head unit by the main drive unit. Therefore, there is a problem that the performance of the piggyback actuator is inferior to the performance of the microactuator alone. According to the present invention, the control of the main drive unit and the control of the auxiliary drive unit are controlled without mutual interference, thereby improving the performance.

As described above, the present invention has the effect of eliminating interference between the main driving means and the auxiliary driving means. As a result, the performance of the piggyback actuator is greatly degraded as compared with the microactuator alone, and the position error suppression characteristic is also deteriorated. Can be solved. The present invention has an effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, a disk device having a high recording density can be obtained.

Embodiment 2 A magnetic disk drive according to Embodiment 2 of the present invention will be described with reference to FIGS. [Explanation of FIG. 8] FIG. 8 is a schematic configuration diagram of a magnetic disk drive according to a second embodiment of the present invention. 1 is a magnetic disk, 2 is a composite magnetic head, 3 is a magnetic head slider,
4 is a head support mechanism, 5 is a rotating shaft of the head support mechanism, 6 is a control unit, 5-1 is a voice coil motor (VCM) as a main drive unit, 5-2 is an auxiliary drive unit, 6-
1 is a head position detector, 6-5 is a relative position calculator, 6
-3-1 is a main drive unit control unit, 6-3-2 is an auxiliary drive unit control unit, 6-4-1 is a main drive unit drive unit, 6-4
Reference numeral -2 denotes an auxiliary driving unit driving unit. In the first embodiment, the amount of movement by the main drive unit is measured using an encoder, but in the second embodiment, the unit for measuring the amount of movement by the main drive unit, the main drive unit estimation unit (estimation unit) Model) and auxiliary driving means estimating means (estimating model). The relative position calculation unit 6-5 estimates the amount of movement of the head unit by the main drive unit.

[Description of FIG. 9] FIG. 9 is a block diagram of the servo system of FIG. An operation sequence of the servo system in the magnetic disk device according to the second embodiment will be described. The relative position calculation unit 6-5 includes a control amount of the main drive unit (output of the main drive unit calculation unit 6-3-1C) and a control amount of the auxiliary drive unit (output of the auxiliary drive unit calculation unit 6-3-2C). And the current position of the head section (output of the head position detecting means 6-1)
And outputs the amount of movement of the head unit by the main drive means. The output movement amount of the head unit by the main drive unit is input to the subtractor 6-3-1A as in the first embodiment. One set of state equations 6-5A is a state equation of the control system including the main drive unit and the auxiliary drive unit. The state equation 6-5A includes a control amount of the main driving unit (output of the main driving unit operation unit 6-3-1C), a control amount of the auxiliary driving unit (output of the auxiliary driving unit operation unit 6-3-2C), and The current position of the head unit (output of the head position detection unit 6-1) is input, and the movement amount of the head unit by the main driving unit and the movement amount of the head unit by the auxiliary driving unit are output.

The subtractor 6-5B subtracts the amount of movement of the head unit by the auxiliary driving unit from the current position of the head unit (output of the head position detection unit 6-1), and subtracts the result (when there is no microactuator). (The current position of the head section). The subtractor 6-5B of the second embodiment plays the same role as the subtractor 6-3-2B of the first embodiment. Therefore, for the operation of the subtractor 6-5B, see the description of the operation of the subtractor 6-3-2B in the first embodiment. Adder 6-5C is the current position of the head unit when there is no microactuator (output of subtractor 6-5B)
And the amount of movement of the head unit by the main drive means, and outputs the result of the addition (the latest current position of the center point of the drive range of the microactuator). Example 2
Is the adder 6-3-1D of the first embodiment.
And play the same role. Therefore, for the operation of the adder 6-5C, see the description of the operation of the adder 6-3-1D in the first embodiment. Otherwise, Example 2
Is the same as in the first embodiment. In FIG. 3 (Embodiment 1) and FIG. 9 (Embodiment 2), the same reference numerals are assigned to the same blocks. The same blocks as in the first embodiment are shown in FIGS.
6 and the description section in FIG.

In another embodiment of the present invention, the moving amount of the head unit by the auxiliary driving means is subtracted from the moving amount of the current head unit position read by the reproducing head, and the moving of the head unit by the main driving means is performed. Find the quantity. Specifically, at the first time, the current position P1 of the head section read by the reproducing head and the movement amount Ps1 of the head section by the auxiliary driving means are stored. Next, the current position P2 of the head portion read by the reproducing head at the second time
And the movement amount Ps2 of the head unit by the auxiliary driving means. The amount of movement of the head by the required driving means is (P2-
P1)-(Ps2-Ps1). The main driving means is controlled based on the estimated movement amount.

[Description of FIGS. 10 to 13] FIGS. 10 to 13 show simulation results of response characteristics according to this embodiment of the present invention. FIG. 10 shows the step response. The settling time for the head section to converge to the target position is just over 1 ms. The target level is 1. The unit of time on the horizontal axis is
Seconds (S). FIG. 11 shows the frequency characteristics of the closed loop. The upper diagram is a gain diagram, and the lower diagram is a phase diagram. FIG.
Shows the transition of the position error signal when a disturbance is applied.
The position error signal indicates a position error when four types of position error factors are input to the servo system. The vertical axis represents the position error (bit), and the horizontal axis represents time (msec). Position error 50
Bits correspond to about 10% of the track pitch. FIG.
Shows a histogram of the residual position error at the time of settling. The three sigma of the position error is 0.0465 μm. The histogram is a frequency distribution of the position error in FIG. The vertical axis indicates frequency, and the horizontal axis indicates position error (bit number).

As in the case of the first embodiment, the performance of the second embodiment is significantly improved as compared with the conventional example. In order to make a quantitative comparison, histograms of residual position errors at the time of settling are compared. As described above, the three sigma of the position error by the control method of Conventional Example 1 or Conventional Example 3 is 0.0952 μm (FIG. 3).
7), and the three sigma of the position error by the control method of Conventional Example 2 was 0.0628 μm (FIG. 41). Although the amount of movement of the head unit by the main driving unit is an estimated value, the three sigma of the position error of the second embodiment of the present invention is as follows.
0.0465 μm (FIG. 13). This position error is
In addition to exceeding the performance of the conventional control method, the position error of the microactuator alone is 3 sigma, 0.0
This is a value approaching 415 μm (FIG. 33). In the embodiment of the present invention, the settling time of the step response is set at slightly more than 1 ms (FIG. 4), which is greatly improved from the settling time of 4 ms (FIG. 34) according to the control method of Conventional Example 1 or Conventional Example 3. Therefore, it is at the same level as compared with the control method of the conventional example 2.

The fact that the residual position error is small means that
When a piezoelectric element or the like is used as the auxiliary driving means, the piezoelectric element is controlled and driven in the vicinity of the center of the operation range, so that it is possible to suppress the influence of a temporal change and hysteresis caused by driving the piezoelectric element excessively. I can do it. As described above, according to the present embodiment, the positioning error of the head portion can be reduced by the piggyback servo system, and the head portion can be positioned with high speed and high accuracy. Note that the estimated value of the moving amount of the head unit by the main drive unit, which is estimated by the relative position calculation unit 6-5 of the second embodiment, is inferior in accuracy to the measured value of the encoder of the first embodiment. 3 sigma of the position error of the second embodiment of the present invention is 3 sigma of the position error of the first embodiment of the present invention.
Slightly worse than Sigma. In the simulation, FIGS. 4 to 7 of the first embodiment and FIGS. 10 to 13 of the second embodiment are very similar. This is because the estimation accuracy of the movement amount by the main drive unit of the second embodiment is considerably high. If the accuracy of estimating the movement amount by the main driving means becomes worse than in the second embodiment, the difference in the figure will be enlarged.

<< Embodiment 3 >> An auxiliary drive means displacement amount estimator according to a third embodiment of the present invention will be described with reference to FIG. [Explanation of FIG. 14] FIG. 14 is a schematic configuration diagram of an auxiliary drive means displacement amount estimator and its peripheral portion according to a third embodiment of the present invention. The third embodiment realizes highly accurate estimation of the moving amount of the head unit by the auxiliary driving unit. The main part of the auxiliary driving means displacement amount estimator of the third embodiment is included in the auxiliary driving means estimating means 6-3-2E (FIG. 3). For example, with the configuration of FIG. 2 (having a piezoelectric element for detecting displacement of the piezoelectric element),
In the disk drive including the auxiliary driving means displacement amount detecting unit 6-2-2 (FIG. 1), the displacement of the head unit by the auxiliary driving means can be actually detected. No estimator is required. However, many disk devices do not include a detector for measuring the actual displacement of the head unit by the auxiliary driving unit, and estimate the displacement (movement amount) of the head unit by the auxiliary driving unit. The displacement amount (movement amount) is obtained.

For example, when a piezoelectric element is used for the auxiliary driving means, the piezoelectric element generates a displacement having a certain relationship with the applied voltage. Therefore, the simplest and most common auxiliary drive means displacement amount estimator is an auxiliary drive means control unit 6-3-3.
2 outputs a control signal (auxiliary driving means driving unit 6-4-2).
It is presumed that a certain displacement of the head portion occurs in accordance with the input signal of the above. When carrying out the invention of claim 1 of the present invention, the above-mentioned general auxiliary drive means displacement amount estimator can be used. However, by providing the auxiliary drive means displacement amount estimator having high accuracy in estimating the movement amount of the head unit by the auxiliary drive means 5-2, it is possible to realize a disk device having a control unit with higher speed and less residual error. Thus, the invention shown in the third embodiment (FIG. 14) constitutes a lower concept invention of the invention as claimed in claim 1 or the like.

In FIG. 14, the displacement estimator of the auxiliary driving means according to the third embodiment has an input / output interface 6-7-1.
, A storage device 6-7-2, and a switch 6-7-3. The external computer 6-7-4 is a computer installed in a factory, and may not be included in the disk device, or may be included in the disk device as described later. In the third embodiment, the amount of displacement caused by the piezoelectric element, which is an auxiliary drive unit of the disk device, is measured one by one at the factory, and the measured data is stored in the storage device 6-7-2 inside the disk device. Even when a constant voltage is applied to a piezoelectric element, the amount of displacement of each element varies greatly. Therefore, the present invention prevents the deterioration of control performance due to the variation of the elements by measuring the amount of displacement for each element and storing the measured amount of displacement in the storage device 6-7-2 inside the disk device. I have.

The disk device according to the third embodiment of the present invention
Input / output interface 6-
It is connected to an external computer 6-7-4 through 7-1. The interface between the external computer 6-7-4 and the input / output interface 6-7-1 is bidirectional, but the main signals are transmitted from the external computer 6-7-4.
7-4 to the input / output interface 6-7-1. The switch 6-7-3 is connected to an external computer 6-7.
As long as there is no special command from -4, it is connected as far as the solid line. The external computer 6-7-4 sends a command to the switch 6-7-3 through the input / output interface 6-7-1, and connects the switch 6-7-4 to the broken line.
Next, the external computer 6-7-4 sends an external control signal (known value) through the input / output interface 6-7-1 and the connection of the dashed line of the switch 6-7-3 to perform auxiliary driving. Means driving section 6-4-2 (auxiliary driving means 5-
Drive 2).

At the factory, the positional information on the disk (output of 6-1 in FIGS. 1 and 8) read by the reproducing head of the disk device is taken out and inputted to the external computer 6-7-4. The external computer inputs and stores the position P3 (position information on the disk read by the reproducing head) of the head unit when the external signal is 0 V,
Further, while changing the external signal at regular intervals,
The position P4 of the head unit of the disk device at that time (position information on the disk read by the reproducing head) is measured and input. The measurement is performed over the entire driving range of the piezoelectric element. The value of the external signal is changed from 0V to the maximum value on the plus side, then to the maximum value on the minus side, and returned to 0V for measurement. Next, the value of the external signal is changed from 0 V to the maximum value on the negative side, then changed to the maximum value on the positive side, and returned to 0 V for measurement. Thus, the displacement amount including the hysteresis of the piezoelectric element is measured. In addition,
P4-P3 is a displacement amount (movement amount) at the position on the disk by the external signal.

When the measurement is completed, the external computer 6-7
-4 sets the initial position of the microactuator near the center. In this way, the microactuator is controlled and driven within a range with good linearity characteristics. The external computer 6-7-4 stores the magnitude of the external control signal and the corresponding displacement (movement) of the head unit of the disk drive. Next, the external computer 6-7-
4 stores, via the input / output interface 6-7-1, information on the magnitude of the external control signal and the displacement amount (movement amount) of the head unit of the corresponding disk device, stored in the external computer. Input to 7-2 and store. When the above processing is completed, the external computer 6
7-4 is disconnected from the input / output interface 6-7-1. The switch 6-7-3 switches to the connection on the solid line side.

In the normal operation of the disk drive of the third embodiment, the auxiliary driving means estimating means 6-3-2E receives the output signal of the auxiliary driving means calculating section 6-3-2C. The auxiliary driving unit estimating unit 6-3-2E refers to the data stored in the storage device 6-7-2 and refers to the auxiliary driving unit calculating unit 6-
A displacement amount (movement amount) of the head unit of the disk device corresponding to the external control signal having the magnitude closest to the 3-2C output signal is selected, and the displacement amount is estimated as an actual displacement amount. At this time, it is desirable to consider the hysteresis (the estimated displacement differs depending on whether the displacement is increasing or decreasing due to the hysteresis).

Further, two external control signals sandwiching the value of the output signal of the auxiliary driving means calculating section 6-3-2C are selected,
By the proportional distribution, the displacement amount corresponding to the output signal of the auxiliary driving means computing unit 6-3-2C can be calculated, and the displacement amount can be estimated as the actual displacement amount. With the above configuration, it is possible to prevent the control performance from deteriorating due to variations in the piezoelectric elements.

At the factory, the above-described measurement work (calibration) performed by an external computer may be performed by a microcomputer built in the disk device. At the time of calibration, the microcomputer incorporated in the disk device reads the positional information of the head unit from the disk for each amount of movement while sequentially changing the amount of movement of the head unit by the auxiliary driving means, and applies the information for displacement of the head unit. Voltage, the actual displacement of the head,
Is plotted. The measurement in consideration of the hysteresis is the same as the case where the measurement is performed in the factory described above. By performing the calibration by the microcomputer incorporated in the disk device, it is possible to eliminate the control deviation due to the aging of the piezoelectric element at any time.

Embodiment 4 A magnetic disk drive according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 15 is a schematic configuration diagram of a magnetic disk drive according to a fourth embodiment of the present invention. 1 is a magnetic disk, 2 is a composite magnetic head, 3 is a magnetic head slider, 4 is a head support mechanism, 5 is a rotation axis of the head support mechanism, 6 is a control unit, 5
-1 is a voice coil motor (VC
M), 5-2: auxiliary driving means, 6-1: head position detecting means, 6-5: relative position calculating section, 6-3-1-a: main driving means control section during track following, 6-3 -2
-A is a track following auxiliary driving means control unit,
6-3-1-b is a main driving means control unit at the time of seek settling, 6-3--2-b is an auxiliary driving means control unit at the time of seek settling, 6-6 is a control switching means, and 6-4-1 is a main driving means. A means driving section, 6-4-2, is an auxiliary driving means driving section.

In the piggyback actuator servo system shown in FIG. 15, at the time of track following (the movement amount is small), the control switching means 6-6 controls the main driving means control unit 6-3-1 at the time of track following.
-A and the auxiliary driving means control unit 6-3-2-a at the time of track following are selected. In this case, the track-following auxiliary driving means control unit 6-3-2-a sets the position error between the target position and the head position to zero.
Control the piezoelectric element microactuator. Main driving means control unit 6-3-1-a during track following
Controls the voice coil motor so that the position error between the target position and the position of the center point of the drive range of the microactuator is made zero. The control in this case is performed according to the second embodiment.
This is the same as (FIG. 8). The position error signal is input to the auxiliary driving means control unit 6-3-2-a at the time of track following, the control amount for the control target is independently calculated, and the microactuator 5-2 is driven. As described in the second embodiment, the relative position calculation unit 6-5 calculates the amount of movement of the head unit by the main driving unit. Based on the calculated amount of movement of the head unit by the main drive unit, the main drive unit control unit at the time of track following is performed.
a controls the main driving means 5-1.

At the time of seek settling (the moving amount is large), the control section is controlled by the control switching means 6-6 and the main drive means control section 6-3-1-b at seek settling time.
Auxiliary drive control unit 6-3-2-b during seek settling
Is selected. In this case, the seek settling auxiliary driving unit control unit 6-3-2-b fixes the piezoelectric element microactuator at the center position of the operation range. At the time of seek settling, the main drive unit control unit 6-3-1-b controls the voice coil motor so that the position error between the target position and the head position is made zero. The seek-settling auxiliary driving means control unit 6-3--2-b outputs a constant signal to the microactuator 5-2 such that the microactuator is fixed at the center of the operation range. Usually, the constant voltage is 0V. The position error signal is transmitted to the main drive unit control unit 6-3-1 during seek settling.
-B, and the voice coil motor is controlled so that the position error becomes zero. In this case, the voice coil motor is controlled similarly to the voice coil motor of a normal disk drive driven by a single voice coil motor.

In FIG. 15, for example, the track-following auxiliary driving means controller 6-3--2-a and the seek settling auxiliary driving means controller 6-3--2-b are displayed as independent blocks. Have been. Specific circuits, devices, and the like that embody the respective blocks may be separate and independent from each other. Further, the present invention is also applicable to a case where the main part of each block is made common and only a part of the circuits is switched so that the control is switched depending on whether the moving amount is large or small. Included in the target range.

In another embodiment, the control means of the auxiliary drive means is switched according to the magnitude of the movement amount, as in the above embodiment, but the control means of the main drive means is not switched. The main drive control unit controls the voice coil motor so that the position error between the target position and the position of the center point of the drive range of the microactuator is zero regardless of the magnitude of the movement amount. During track following,
Since the microactuator is fixed at the center of the operating range, this embodiment and the above embodiment perform substantially the same operation.

When the movement amount is large, for example, if the control of the second embodiment is performed as it is, the microactuator is displaced as far as possible to a far distant target. Considering the aging of the piezoelectric element and the like, it is not preferable to control the microactuator so that the microactuator does not have the effect of driving the microactuator and that the microactuator must be forced when moving far away. The microactuator has an operation range of about ± several tracks to one track, and during settling during seek or track jump (movement is large), it is possible to limit the drive of the microactuator to be within the operation range. is necessary. Further, also at the time of track following (the moving amount is small), it is necessary to perform control driving within a range in which the linearity of the output characteristic of the microactuator is guaranteed. That is, control driving of the auxiliary driving means near the center of the operation range,
desirable. Therefore, in the present invention of the fourth embodiment, the microactuator is rested (not driven) at the time of moving to a far distance where the microactuator is useless.

According to this control method, even when the controller of the control system is independently designed as in the first and second embodiments, even when the moving amount is large, the conventional method can be used.
The auxiliary driving means does not perform excessive displacement. The auxiliary drive means is controlled and driven near the center of a reasonably linear operation range when the target position is sufficiently approached. As a result, excessive driving of the piezoelectric element is not performed, so that the time-dependent change of the microactuator can be reduced, and the hysteresis is reduced because the large-amplitude driving is not performed. ), The settling time of the transient response is improved. Conventionally, the microactuator is displaced as far as possible to the left and approaches the target position, for example, so that when approaching the target position, the drive range of the microactuator is zero to the left ( (Because it was already fully displaced to the left), it was in an unbalanced state that it could be driven to the right. According to the present invention, since the microactuator is always used near the center of operation, considering that the microactuator shakes the head part right and left when approaching the target, the drive range to the left and the drive to the right Since the range is balanced (a range of similar size), the transient response is smooth and settles quickly. As described above, according to this embodiment, the position error can be reduced and the composite head can be positioned with high speed and high accuracy.

In this embodiment, the microactuator of the piggyback actuator is of the piezoelectric element type. However, the same effect can be obtained by other types of microactuators such as an electrostatic type, an electromagnetic type, a magnetostrictive type and a shape memory alloy type. can get. Further, in the present embodiment, a controller which is a controller,
Although the feedback gain and the feedforward gain of the observer, which is a state estimator, are designed in a pole arrangement manner, similar effects can be obtained by the frequency response method, the H∞ method, the μ design method, the LMI design method, and the like.

Further, in this embodiment, an encoder slit is arranged on the VCM coil side and an optical detection system is arranged on the housing side to detect the relative displacement of the VCM. However, the same effect can be obtained even if the sensor uses another principle such as a diffraction grating application or an optical interference application.

In this embodiment, the piezoelectric microactuator of the piggyback actuator is formed on the suspension. However, the same effect can be obtained by forming the gimbal portion, the slider portion, or the arm portion. Further, the microactuator of this embodiment is of a push-pull type, but may be of another type such as a rotary type.

In this embodiment, the piezoelectric element is attached on the piezoelectric element microactuator in order to detect the relative displacement of the microactuator. However, the sensor is not limited to the piezoelectric element, and the detection position is not limited to the slider position. The same effect can be obtained in other parts. In this embodiment, a thin-film piezoelectric element is used as the piezoelectric element, but the same effect can be obtained with a bulk piezoelectric element.

[0135]

According to the present invention, it is possible to control the microactuator, which is the auxiliary driving means, in a high band, and it is possible to realize a disk device that can settle at high speed and reduce a position error. Is obtained. As a result, according to the present invention, there is obtained an advantageous effect that a disk device having a short settling time and a small residual position error at the time of settling can be obtained. Accordingly, an advantageous effect that a disk device having a high recording density can be obtained. In particular, the advantageous effect of obtaining a magnetic disk device requiring high-speed and high-precision access can be obtained.

Further, according to the present invention, there is obtained an advantageous effect that a disk drive which does not excessively drive the auxiliary driving means can be obtained. As a result, it is possible to reduce the change over time of the moving amount of the auxiliary driving means such as the piezoelectric element and extend the life of the auxiliary driving means. Further, since the hysteresis of the auxiliary driving means such as the piezoelectric element can be suppressed to a small value, the settling time can be shortened, and the residual position error at the time of the settling can be reduced. Also,
Since the auxiliary driving means is driven near the center of the operation range, control can be performed in a state where the left and right control ranges (pull-in range or hold range) are sufficiently ensured. Therefore, the present invention has an advantageous effect that a settling time is short and a disk device having a small residual position error at the time of settling can be obtained. Accordingly, an advantageous effect that a disk device having a high recording density can be obtained.

According to the present invention, the advantageous effect that interference between the main driving means and the auxiliary driving means can be eliminated can be obtained. As a result, the performance of the piggyback actuator is greatly degraded as compared with the microactuator alone, and the position error suppression characteristic is also deteriorated. Can be solved. Therefore,
ADVANTAGE OF THE INVENTION This invention has the advantageous effect that the settling time is short and the disk device with a small residual position error at the time of settling is obtained. Therefore, by extension, a disk device with a high recording density
This has the advantageous effect of being obtained.

According to the present invention, the advantageous effect that interference between the main driving means and the auxiliary driving means can be eliminated is obtained. As a result, as compared with the microactuator alone, the performance of the piggyback actuator is greatly degraded, and the position error suppression characteristic is also deteriorated. Can be solved. Therefore,
ADVANTAGE OF THE INVENTION This invention has the advantageous effect that the settling time is short and the disk device with a small residual position error at the time of settling is obtained. Therefore, by extension, a disk device with a high recording density
This has the advantageous effect of being obtained.

According to the present invention, the interference between the main driving means and the auxiliary driving means is eliminated, and the relative movement amount of the head by the main driving means is inputted to the control system of the main driving means. The advantageous effect that the settling time of the control of the main drive means can be improved is obtained. Therefore, according to the present invention, there is obtained an advantageous effect that a disk device having a short settling time and a small residual position error at the time of setting can be obtained, and a disk device having a high recording density can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a magnetic disk drive according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a microactuator of the magnetic disk drive according to the first embodiment of the present invention;

FIG. 3 is a block diagram of a servo system of the disk drive according to the first embodiment of the present invention;

FIG. 4 is a step response diagram of the disk device according to the first embodiment of the present invention.

FIG. 5 is a closed loop frequency characteristic diagram of the disk device according to the first embodiment of the present invention.

FIG. 6 is a transition diagram of a position error signal when a disturbance is applied to the disk device according to the first embodiment of the present invention.

FIG. 7 is a histogram of a residual position error at the time of settling of the disk device according to the first embodiment of the present invention.

FIG. 8 is a structural diagram of a microactuator of a magnetic disk drive according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a servo system of a disk drive according to a second embodiment of the present invention;

FIG. 10 is a step response diagram of the disk drive according to the second embodiment of the present invention;

FIG. 11 is a frequency characteristic diagram of a closed loop of the disk device according to the second embodiment of the present invention;

FIG. 12 is a transition diagram of a position error signal when a disturbance is applied to the disk device according to the second embodiment of the present invention.

FIG. 13 is a histogram of a residual position error at the time of settling of the disk device according to the second embodiment of the present invention.

FIG. 14 is a schematic configuration diagram of an auxiliary driving unit displacement amount estimator and its peripheral portion according to a third embodiment of the present invention;

FIG. 15 is a schematic configuration diagram of a magnetic disk drive according to a fourth embodiment of the present invention.

FIG. 16 is a detailed block diagram of a main driving unit calculating unit 6-3-1C and a main driving unit estimating unit 6-3-1E.

FIG. 17 is a detailed block diagram of an auxiliary driving means calculating unit 6-3-2C and an auxiliary driving means estimating means 6-3-2E.

FIG. 18 is a schematic configuration diagram of a piggyback actuator of a first conventional disk recording / reproducing apparatus.

FIG. 19 is a schematic configuration diagram of a piggyback actuator of a second conventional disk recording / reproducing apparatus.

FIG. 20 is a schematic configuration diagram of a piggyback actuator of a third conventional disk recording / reproducing apparatus.

FIG. 21 is a schematic configuration diagram of a fourth piggyback actuator.

FIG. 22 is a schematic configuration diagram of a fifth piggyback actuator.

FIG. 23 is a block diagram showing a control method of a piggyback actuator of the disk recording / reproducing apparatus of Conventional Example 1.

FIG. 24 is a block diagram showing a control method of a piggyback actuator of the disk recording / reproducing apparatus of Conventional Example 2;

FIG. 25 is a block diagram showing a control method of a piggyback actuator of the disk recording / reproducing apparatus of Conventional Example 3.

FIG. 26 is a step response diagram when the disk device is controlled by a single voice coil motor (main driving means).

FIG. 27 is a frequency characteristic diagram of a closed loop when the disk device is controlled by a single voice coil motor (main driving unit).

FIG. 28 is a transition diagram of a position error signal when a disturbance is applied when the disk device is controlled by a single voice coil motor (main driving unit).

FIG. 29 is a histogram of a residual position error at the time of settling when a disk device is controlled by a single voice coil motor (main driving unit).

FIG. 30 is a step response diagram when the disk device is controlled by a single microactuator (auxiliary driving means).

FIG. 31 is a frequency characteristic diagram of a closed loop when a disk device is controlled by a microactuator (auxiliary driving means) alone.

FIG. 32 is a transition diagram of a position error signal when a disturbance is applied when the disk device is controlled by a single microactuator (auxiliary driving unit).

FIG. 33 is a histogram of a residual position error at the time of settling when a disk device is controlled by a microactuator (auxiliary driving means) alone.

FIG. 34 is a step response diagram when the disk device is controlled by the same control method as in Conventional Example 1 or 3;

FIG. 35 is a frequency characteristic diagram of a closed loop when a disk device is controlled by a control method similar to that of Conventional Example 1 or 3;

FIG. 36 is a transition diagram of a position error signal when a disturbance is applied when the disk device is controlled by the same control method as the conventional example 1 or 3;

FIG. 37 is a histogram of a residual position error at the time of settling when the disk device is controlled by the same control method as in Conventional Example 1 or 3.

FIG. 38 is a step response diagram when the disk drive is controlled by the same control method as that of the conventional example 2;

FIG. 39 is a frequency characteristic diagram of a closed loop when the disk device is controlled by the same control method as in the second conventional example.

FIG. 40 is a transition diagram of a position error signal when a disturbance is applied when the disk device is controlled by the same control method as in the second conventional example.

FIG. 41 is a histogram of a residual position error at the time of settling when the disk drive is controlled by the same control method as in the second conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Composite magnetic head 3 Magnetic head slider 4 Head part support mechanism part 5 Rotation axis of head part support mechanism part 6 Control part 5-1 Main drive means (voice coil motor (VC
M)) 5-2 Auxiliary drive unit 6-1 Head position detection unit 6-2 Relative position detection unit 6-3-1 Main drive unit control unit 6-3-2 Auxiliary drive unit control unit 6-4-1 Main drive Means drive unit 6-4-2 Auxiliary drive unit drive unit 6-2-1 Main drive unit displacement amount detection unit 6-2-2 Auxiliary drive unit displacement amount detection unit 6-5 Relative position calculation unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuhiko Inagaki 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Toshiyuki Wada 1006 Kadoma Kadoma, Kadoma City Osaka Pref. Terms (Reference) 5D088 PP01 RR10 SS01 SS13 TT10 UU01 5D096 NN03 NN07

Claims (9)

[Claims] 1. A disc on which information data is recorded, a head unit including a reproducing head for reproducing data recorded on the disc, a head slider on which the head unit is mounted, and a head slider supporting the head slider, A head support mechanism for supporting the head in opposition to the disk; a main drive unit for driving the head support to move the head; and driving the head or the head slider. And a control unit for controlling the main driving unit and the auxiliary driving unit. The control unit controls the head based on a reproduction signal of a reproduction head. Head position detecting means for detecting the current position of the head, and a first relative position for detecting or estimating the amount of movement of the head by the main drive means Output means; an auxiliary drive control section for controlling the auxiliary drive based on information including a position error between a target position of the head section and a current position of the head section; and the first relative position detection. A main drive unit control unit for controlling the main drive unit based on information including the movement amount of the head unit detected or estimated by the unit. 2. The main drive unit estimation unit that estimates a state quantity of the head unit including a movement amount of the head unit by the main drive unit and a movement speed of the head unit by the main drive unit. The disk drive according to claim 1, wherein the main drive unit control unit controls the main drive unit based on information including a state quantity of the head unit. 3. The control section further includes a second relative position detecting section for detecting or estimating a moving amount of the head section by the auxiliary driving section, wherein the first relative position detecting section includes the reproducing section. The difference between the amount of movement of the head unit calculated based on the reproduction signal of the head and the amount of movement of the head unit by the auxiliary drive unit output by the second relative position detection unit is determined by the main drive unit The disk device according to claim 1, wherein the amount is estimated to be a movement amount. 4. A disk on which information data is recorded, a head unit including a reproducing head for reproducing data recorded on the disk, a head slider mounting the head unit, and a head slider supporting the head slider. A head support mechanism for supporting the head in opposition to the disk; a main drive unit for driving the head support to move the head; and driving the head or the head slider. And a control unit for controlling the main drive unit and the auxiliary drive unit, wherein the control unit controls the head unit to approach a target position. A first auxiliary driving unit control unit for controlling the auxiliary driving unit, and a moving amount by the auxiliary driving unit is set to zero or a constant value. A second auxiliary driving unit control unit for controlling the auxiliary driving unit; and a control switching for switching any one of the first auxiliary driving unit control unit and the second auxiliary driving unit control unit to operate effectively. Means, and a disk device. 5. The control unit further includes a second relative position detection unit that detects or estimates an amount of movement of the head unit by the auxiliary drive unit, and the auxiliary drive unit control unit further includes: The method according to any one of claims 1 to 4, wherein the auxiliary driving unit is controlled based on information output from the second relative position detecting unit and including the moving amount of the head unit. Disk device described. 6. The second relative position detecting means includes: a moving amount storing means for storing a measured moving amount of the head unit by the auxiliary driving means; and a moving amount storage means for storing the measured moving amount of the head unit based on the measured moving amount. The disk device according to claim 5, further comprising: a relative position estimating unit that estimates a moving amount of the head unit. 7. The main driving unit estimating unit, wherein an output of the main driving unit control unit is not interfered with an output of the auxiliary driving unit control unit,
The disk device according to any one of claims 1 to 6, comprising: 8. The control unit further includes: an auxiliary drive unit estimating unit, wherein an output of the auxiliary drive unit control unit is not interfered with by an output of the main drive unit control unit.
The disk device according to any one of claims 1 to 7, comprising: 9. A disk on which information data is recorded; a head unit including a reproducing head for reproducing data recorded on the disk; a head slider on which the head unit is mounted; A head support mechanism for supporting the head in opposition to the disk; a main drive unit for driving the head support to move the head; and driving the head or the head slider. A control unit for controlling the main drive unit and the auxiliary drive unit, the control unit comprising: a control unit that controls the main drive unit and the auxiliary drive unit; Detecting a current position; a relative position detecting step of detecting or estimating a moving amount of the head unit by the main driving unit; Controlling the auxiliary driving unit based on information including a position error between a target position of the unit and a current position of the head unit; and a movement amount of the head unit detected or estimated in the relative position detection step. Controlling the main drive unit based on the information including the following.