JP2000311454A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device being inexpensive and having high track density in which deviation of tracking of a head caused by the eccentricity of a disk can be suppressed. SOLUTION: This disk device is constituted so that a position detecting means 10 generates an error signal (e) corresponding to the position of a head 2 from servo information of a disk, a position control means 11 generates a control signal (c) corresponding to an error signal (e), a disturbance estimating means 14 forms a disturbance estimating signal Fd indicating magnitude of position disturbance from a drive signal (u) inputted to a drive circuit 12 driving an actuator means 7 and the error signal (e) and output it to a compensating means 15, and the drive signal (u) is compensated from a compensating signal βformed by the compensating means 15 and the control signal (c) formed by the position control means 11.

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 recording / reproducing head such as a magnetic head or an optical head to a desired position on a target track of a disk as a recording medium by an actuator with high accuracy.

[0002]

2. Description of the Related Art In recent years, the size and capacity of magnetic disk drives have been rapidly increasing. In particular, in response to the increase in the capacity of the magnetic disk drive, the track density of the magnetic disk has been increasing, and the track pitch tends to be narrower. Therefore, in the magnetic disk drive, in order to record and reproduce data on the magnetic disk, it is necessary to position the magnetic head with high accuracy on a target track formed with a narrow track pitch. In a conventional magnetic disk drive, servo information is formed in advance on a magnetic disk in order to position a magnetic head, and positioning control of the magnetic head is performed according to the servo information. That is, in the conventional magnetic disk drive, an error signal indicating a position error of the magnetic head with respect to the target track is generated by reading the servo information with the magnetic head, and the positioning of the magnetic head is controlled so that the error signal is minimized. I have.

Accordingly, in order to increase the positioning accuracy of the magnetic head, the control frequency of the magnetic head positioning control system is set to be high, and the magnetic head is quickly positioned on the target track to secure the required positioning accuracy. Was. However, there are cases where higher-order mechanical resonance exists in the actuator itself of the positioning mechanism. In this case, if the control frequency is increased in order to increase the positioning accuracy, there is a problem that the mechanical resonance causes unstable positioning control. Was. Therefore, since the band of the control frequency of the positioning control system is actually limited by the higher-order mechanical resonance of the actuator itself, there is a limit in increasing the control frequency of the positioning control system. In particular, it is extremely difficult for a magnetic disk drive to keep a high-precision positioning state and make a magnetic head follow a target track with respect to track deviation due to eccentricity of a magnetic disk rotating at the same frequency as the rotation frequency of a spindle motor. Met.

Next, problems in positioning control in the case of an actuator having higher-order mechanical resonance will be described. FIG. 9 is a frequency characteristic diagram showing a transfer characteristic of a displacement amount of a magnetic head with respect to a drive signal input to a rotary actuator having a moment of inertia. In the frequency characteristic diagram shown in FIG. 9, in the rotary actuator having the moment of inertia, the gain characteristic of the amount of displacement of the magnetic head with respect to the input drive signal changes with increasing angular frequency by -4.
It is attenuated at an attenuation ratio of 0 dB / dec (decade). Further, as shown in FIG. 9, the phase characteristic of the transfer characteristic is
A phase lag of about -180 degrees has already occurred in the low frequency range of the angular frequency. Furthermore, in the high frequency range of the angular frequency, the natural vibration caused by the bearing spring of the rotating shaft appears in the frequency characteristic, and a resonance point 31 and an anti-resonance point 32 are generated in the gain characteristic of the frequency characteristic. These resonance point 31 and anti-resonance point 3
2, the gain characteristic changes rapidly, and the phase characteristic is -1.
A further phase delay occurs from 80 degrees to about -360 degrees.

Therefore, when an actuator having a transmission characteristic as shown in FIG. 9 is used, even if phase compensation (phase lead compensation) is performed for stabilizing a positioning control system using a known positioning control mechanism, for example, The control band of the positioning mechanism could not be increased to an angular frequency equal to or higher than the resonance point 31. In recent magnetic disks, the control band of the magnetic head positioning control system cannot be expanded to a high frequency range, and high positioning accuracy cannot be compensated. As a result,
In the conventional magnetic disk drive, depending on the magnitude of the eccentricity of the magnetic disk, the positioning accuracy of the magnetic head cannot be compensated for by the conventional positioning control mechanism alone.

In the conventional magnetic disk drive, several methods have been proposed for improving the positioning accuracy of the magnetic head positioning control system with respect to the eccentricity of the magnetic disk. As an example of a method for improving the positioning accuracy, there is an optical information recording / reproducing apparatus disclosed in Japanese Patent Application Laid-Open No. 1-213838. In Japanese Patent Application Laid-Open No. Hei 1-220138, eccentricity information for one rotation of a disk is stored in a memory, data stored in accordance with the phase of eccentricity is read, and a signal component for canceling eccentricity is superimposed on a drive signal of an actuator. Is disclosed. That is, this method is a method of learning eccentricity information using the fact that the eccentricity component is a periodic signal, and performing feedforward control based on the learned result.

Japanese Patent Application Laid-Open No. 2-246063 discloses a head positioning control circuit. JP-A-2-
The head positioning control circuit disclosed in Japanese Patent No. 246063 generates a sine wave having the same fundamental frequency as the rotation speed of a magnetic disk in a sine wave generator, and the sine wave is optimized based on a position error signal reproduced from the magnetic disk by a magnetic head. Phase and size are adjusted. This head positioning control circuit compensates for a decrease in the positioning accuracy of the magnetic head due to disk eccentricity by adding the adjusted sine wave as a feedforward signal to the position feedback loop system.

[0008]

In order to increase the track density of the magnetic disk drive and to ensure the positioning accuracy with respect to the eccentricity of the magnetic disk, the former (Japanese Patent Laid-Open No. 1-22) has been proposed.
0138) requires a memory for storing eccentricity information for one rotation of the disk, and the latter method (Japanese Patent Application Laid-Open No. 2-246063) generates the same fundamental frequency as the rotation speed of the disk. Required a sine wave generator. For this reason, in the conventional disk device, a memory and a sine wave generator must be provided, and a circuit board area must be increased in order to mount the memory and the sine wave generator. There was a problem.

According to the present invention, even when a high-order mechanical resonance exists in the actuator itself and the control band of the head positioning control system cannot be increased so much, the memory for storing the eccentricity information of the disk and the rotational speed of the disk can be used. It is not necessary to provide a sine wave generator having the same fundamental frequency, and an object of the present invention is to provide a disk device having high positioning accuracy even for an eccentric disk.

[0010]

A disk apparatus according to the present invention has a head for recording and reproducing data on and from a disk, and a drive signal is input to move the head to a position facing a target track on the disk. Actuator means, drive means for supplying drive power to the actuator means, position detection means for generating and outputting an error signal corresponding to the current position of the head from servo information of the disk detected by the head, Position control means for generating and outputting a corresponding control signal; disturbance estimation means for estimating a magnitude of a position disturbance applied to the head from the error signal and the drive signal; and outputting a disturbance estimation signal; and inputting the disturbance estimation Correction means for correcting a signal of a specific frequency in a signal and outputting a correction signal, and the control signal and the correction signal Comprising a summing means for generating a motion signal output.

According to the disk device of the present invention, the actuator can be driven based on the drive signal corrected by the correction signal having the angular frequency equal to the rotation speed of the spindle motor. Therefore, for the position disturbance due to the eccentricity of the disk,
The head can follow a target track while maintaining a highly accurate positioning state. As a result, there is no need to provide a memory for storing the eccentricity information of the disk or a sine wave generator having the same fundamental frequency as the disk rotation speed.

A disk device according to another aspect of the present invention includes a head for recording and reproducing data on a disk,
Actuator means for receiving a drive signal to move the head to a position facing a target track on the disk, driving means for supplying drive power to the actuator means, and the head based on servo information of the disk detected by the head Position detecting means for generating and outputting an error signal corresponding to the current position, position control means for generating and outputting a control signal corresponding to the error signal, and a magnitude of a position disturbance applied to the head from the error signal and the control signal. Disturbance estimation means for estimating the disturbance and outputting a disturbance estimation signal, correction means for receiving the disturbance estimation signal and outputting a correction signal, and adding means for generating and outputting a drive signal from the control signal and the correction signal. I do.

According to the disk drive of the present invention, the actuator can be driven based on the control signal corrected by the correction signal having the angular frequency equal to the rotation speed of the spindle motor.
Therefore, the head can follow a desired track while maintaining a highly accurate positioning state with respect to position disturbance due to eccentricity of the disk. As a result, the eccentric component can be suppressed without specially providing a memory for storing the eccentricity information of the disk or a sine wave generator having the same basic frequency as the rotation speed of the disk. Further, since the control signal is input to the disturbance estimator instead of the drive signal, the configuration of the disturbance estimator can be simplified, and the positioning accuracy of the head can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic disk drive as a preferred embodiment of a disk drive according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 shows Embodiment 1 according to the present invention.
FIG. 2 is a block diagram showing a configuration of a main part of the magnetic disk device of FIG. In FIG. 1, data is recorded and reproduced by a magnetic head 2 on a magnetic disk 1 rotated by a spindle motor (not shown). The magnetic head 2 is mounted on one end of an arm 3 that rotates around a bearing 4, and the rotation of the arm 3 moves the magnetic head 2 to a position facing a target track of the magnetic disk 1. Actuator 7
A magnet (not shown) is disposed on a surface of the stator 6 facing the drive coil 5, and a magnetic flux generated by the magnet and a drive current supplied to the drive coil 5 from the drive circuit 12 of the positioning control system. The arm 3 is configured to rotate by interaction with Ia. Actuator 7
Are a magnetic head 2, an arm 3, a bearing 4, a drive coil 5,
And the stator 6.

As shown in FIG. 1, the positioning control system in the magnetic disk drive of the first embodiment includes a position detector 10 for detecting the position of the magnetic head 2, a position controller 11 for generating a control signal c, and a drive coil. 5 has a drive circuit 12 for supplying a drive current Ia. Further, the positioning control system includes a disturbance estimator 14 that estimates a position disturbance and outputs a disturbance estimation signal Fd, a corrector 15 that receives the disturbance estimation signal Fd and generates a correction signal β, and a control signal c and a correction signal. Signal β
Is provided. A position signal is recorded in each sector of the magnetic disk 1 in advance, and the position signal is read by the magnetic head 2. The position detector 10 detects the current position of the magnetic head 2 based on the position signal read by the magnetic head 2, and generates an error signal e indicating a difference from the target position of the target track. The position controller 11 receives the error signal e generated by the position detector 10, performs amplification and phase compensation, generates a control signal c, and outputs the control signal c to the adder 13. The disturbance estimator 14 includes:
An error signal e output from the position detector 10 and a drive signal u input from the adder 13 to the drive circuit 12 are input, a position disturbance applied from the outside to the actuator 7 is estimated, and a disturbance estimation signal Fd is output. . The corrector 15 corrects a signal of a specific frequency of the disturbance estimation signal Fd output from the disturbance estimator 14, and outputs a correction signal β. Adder 13
Is the control signal c output from the position controller 11 and the corrector 15
Is added to the correction signal β generated in step (1), and is output to the drive circuit 12 as a drive signal u. The drive circuit 12 supplies a current Ia to the drive coil 5 according to the input drive signal u, and rotates the arm 3 around the bearing 4. As a result,
The magnetic head 2 attached to the tip of the arm 3 is moved to a position facing the target track. In the disk device according to the first embodiment configured as described above, the positional deviation with respect to the target track caused by the externally applied positional disturbance is canceled by the formed correction signal β.

[Operation of Positioning Control System] Next, Embodiment 1
The operation of the positioning control system of the disk device will be described with reference to FIG. FIG. 2 is a block diagram showing an overall configuration of a head positioning control system in the disk device of the first embodiment.
4 is a block diagram of the compensator 15; In FIG. 2,
s represents the Laplace operator. In FIG. 2, a time delay element caused by sampling of the sector servo can be dealt with by well-known phase compensation, so that it is omitted for the sake of simplicity. In FIG. 2, if the current track position detected by the magnetic head 2 is x, the position error ε with respect to the target track position r is given by the following equation (2).
The position error ε is obtained by the subtractor 61.

[0018]

(Equation 2)

In FIG. 2, the position detector 10 represented by a block 41 generates an error signal e (= Kd · ε) which is a transfer function Kd times the position error ε output from the subtractor 61. Here, the transfer function Kd indicates the detection sensitivity of the position detector 10. The position controller 11 represented by the block 42 adds the transfer function Gc to the error signal e output from the position detector 10.
The filter processing of (s) is performed, a control signal c is generated, and output to the adder 13. The control signal c becomes the drive signal u via the adder 13 and is input to the drive circuit 12 represented by the block 43. In the drive circuit 12 of the block 43, the drive signal u is converted from a voltage signal to a gm-fold current signal, and outputs a current Ia.

Actuator 7 represented by block 44
In the above, the current Ia supplied to the drive coil 5 is converted into the driving force F by the transfer function Kf by the interaction with the magnetic flux of the magnet. Here, the transfer function Kf is a force constant of the actuator 7. The transfer function of the block 45 represents a transfer characteristic from the driving force F acting on the arm 3 to the current track position x of the magnetic head 2, and more accurately uses the moment of inertia J of the arm 3 and the length L of the arm 3. What is to be expressed is equivalently converted to mass M and 1 / Ms ²
It is represented by In the block diagram of FIG. 2, the position disturbance xd such that the target track meanders due to the eccentricity of the axis of the spindle motor for rotating the magnetic disk 1 is represented by:
It can be expressed in a form to be input to the adder 66 at the subsequent stage of the block 45.

In FIG. 2, the disturbance estimator 14 surrounded by a dashed line has the same transfer function as the transfer function 1 / Ms ² of the block 45, and the block 52 and the block 5
3 and the block 54 correspond. The drive signal u input to the block 43 is supplied to the block 5 of the disturbance estimator 14.
1 is input and multiplied by gm · Kf.
, A driving force signal f converted by the same transfer function as the driving force F acting on the driving force F is obtained. Block 52 for driving force signal f
Is multiplied by 1 / M to obtain an acceleration estimation signal Aest. In FIG. 2, a combination of the blocks 51 and 52 is referred to as a second multiplier 50. The acceleration estimation signal Aest output from the second multiplier 50 is input to an adder 63, and the adder 63 outputs an acceleration estimation signal τ. The acceleration estimation signal τ is input to and integrated by a first integrator represented by a block 53, and the first integrator outputs the speed estimation signal V
Output est. The speed estimation signal Vest is input to the second integrator represented by the block 54 via the adder 64. The second integrator integrates again to form the position estimation signal Xest.

When the magnetic head 2 is on-track to the target track position r, it can be regarded that r = 0, and from the equation (2), the current track position x of the magnetic head 2 is obtained.
Is equal to the position error ε plus a negative sign (ε
= R-x = -x). Therefore, the error signal e input from the block 41 is input to the first multiplier represented by the block 58. Head position X (equal to -e / Kd) obtained by multiplying by -1 / Kd in block 58 and block 5
The position estimation signal Xest obtained in step 4 is input to the subtractor 65, and a difference signal α is obtained. The above-described difference signal α is input to the third multiplier represented by the block 55, multiplied by g ₁ , and added to the adder 64. Further, the difference signal α is input to the fourth multiplier represented by the block 56, and g ₄
It is multiplied and added to the adder 63. Note that block 55
The coefficient g ₁ of the block 56 and the coefficient g _{2 of the} block 56 are
Is a constant for stabilizing the operation of. The details will be described later. Next, at block 57, the subtractor 6
5 is multiplied by g ₂ · M, and the disturbance estimation signal Fd
To form

Note that the first multiplier (block 58), the second multiplier (blocks 51 and 52), the third multiplier (block 55), the fourth multiplier (block 56), Each of the integrator (block 53) and the second integrator (block 54) is configured by an analog filter. In FIG. 2, a portion surrounded by a broken line is a compensator 15.
FIG. In the corrector 15, a block 71 is a filter whose transfer function is represented by F (s), and a disturbance estimation signal Fd output from the disturbance estimator 14.
Is corrected, and a signal fc is output. The block 72 in the compensator 15 converts the signal fc to 1 / gm
Multiply by Kf and output the correction signal β to the adder 13; That is, the corrector 15 calculates the disturbance estimation signal Fd as 1 / gm · K
By multiplying by f, an input signal β to the drive circuit 12 necessary for generating a driving force of a magnitude corresponding to the disturbance estimation signal Fd in the arm 3 is formed.

[Operation of Disturbance Estimator 14] Next, the operation of the disturbance estimator 14 will be described in detail with reference to FIG.
FIG. 3A is a block diagram in which the input position (subtractor 65) of the head position X is equivalently transformed and moved in the block diagram of FIG. 2 to arrange the block diagram of FIG.
FIG. 3B is a block diagram simply expressing the block diagram of FIG. Input point of the head position X indicated by subtractor 65 in FIG. 2, the size as Ms ² x, 3
(A) can be equivalently converted to the position of the subtractor 67. Focusing on the subtractor 67 in FIG. 3A, γ, which is the output of the subtractor 67, is expressed by the following equation (3).

[0025]

(Equation 3)

Next, focusing on the adder 66 of FIG. 2, there is a relationship represented by the following equation (4).

[0027]

(Equation 4)

From the equations (3) and (4), the subtractor 67
Is the position disturbance xd applied to the magnetic head 2
Is multiplied by Ms ² to be equal to the result of adding a negative sign. By the way, Ms ² xd obtained by multiplying the position disturbance xd by Ms ² is equal to the input when the input position of the position disturbance xd at the subsequent stage of the block 45 in FIG. Physically, acceleration disturbance fd applied to arm 3
Is equivalently converted to Therefore, from the block diagram of FIG. 3A, the acceleration disturbance fd (= M
When a transfer function from s ² xd) to the disturbance estimation signal Fd is obtained, the transfer function is represented by the following equation (5).

[0029]

(Equation 5)

That is, the disturbance estimator 14 shown in FIG.
Can be simplified as shown in FIG. 3 (b). From the equation (5), the disturbance estimator 14 calculates the head position X by a loop in a block surrounded by a dashed line in FIG.
From the drive signal u and the actual acceleration disturbance fd (= Ms ² x
It can be seen that d) can be estimated by a second-order delay system. here,
If the natural angular frequency of the second-order delay system is ωo and the damping factor is ζo, the constants g ₁ and g ₂ for stabilizing the operation of the disturbance estimator 14 are expressed by the following equations (6) and (7), respectively. Is done.

[0031]

(Equation 6)

[0032]

(Equation 7)

Here, if the natural angular frequency ωo is selected to be sufficiently higher than the distribution angular frequency of disturbance applied to the magnetic disk drive from the outside, and the damping factor ζo is selected to be 0.7 to 1,
Acceleration disturbance fd (= Ms ² × d) by the disturbance estimator 14
Can be estimated very accurately.

[Operation of Corrector 15] Next, the operation of the corrector 15 will be described. First, the compensator 15 shown in FIG.
The operation of the disk device according to the first embodiment in the case where the filter F (s) shown in the block 71 is not provided, that is, in the case where F (s) is 1, in the block representing. FIG. 4A is a block diagram in which a portion from the subtractor 13 to the adder 66 related to the operation of the corrector 15 is extracted from the block diagram of FIG. FIG.
(B) is a block diagram in which the position disturbance xd applied to the adder 66 and the acceleration disturbance fd (= Ms ² xd) applied to the block 81 are combined into one using the position disturbance xd. Components having the same functions as those in the block diagram of FIG. 2 are denoted by the same reference numerals, and redundant description will be omitted.

In the block diagram of FIG. 4A, a block 81 has a transfer function represented by equation (5). on the other hand,
The adder 66 has a position disturbance x as shown in FIG.
d is the transfer function G of the block 82 represented by the following equation (8).
It is added to the positioning control system through d (s).

[0036]

(Equation 8)

FIG. 5 is a graph showing the frequency characteristics of the transfer function Gd (s) in the equation (8), where F (s) = 1, that is,
This is a frequency characteristic when there is no block 71. From the frequency characteristics of the transfer function Gd (s) shown in FIG.
At a lower angular frequency, the gain is 0 dB or less and attenuates at an attenuation ratio of -20 dB / dec (decade) as the angular frequency ω falls. That is, the transfer function Gd (s) has a low-frequency cutoff filter characteristic that can suppress an angular frequency lower than the natural angular frequency ωo from the equations (6), (7), and (8). That is, even if the position disturbance xd such that the target track of the magnetic disk meanders acts on the positioning control system due to the eccentricity of the spindle motor or the like, the magnetic disk device of the first embodiment uses the position disturbance xd by the disturbance estimator 14. And the disturbance estimation signal Fd (= Ms ² × d) corresponding to the position disturbance is
Output. Therefore, the positioning control system according to the first embodiment performs the disturbance estimation signal Fd so as to cancel the position disturbance xd.
Is configured to operate.

The transfer function Gd (s) represented by the equation (8)
Has a low-frequency cutoff filter characteristic capable of suppressing an angular frequency lower than the natural angular frequency ωo as described above. Therefore, if the natural angular frequency ωo is set appropriately large, it is possible to suppress the tracking deviation of the magnetic head 2 from the target track due to the position disturbance xd. The above is the operation of the magnetic disk drive when F (s) = 1, that is, when there is no block 71 in the corrector 15.

However, if the track pitch becomes narrower in order to increase the track density in order to increase the capacity of the magnetic disk drive, position disturbances such as eccentricity, which are small and do not cause any problem in the conventional drive, are not particularly problematic. Cannot be ignored. The magnetic disk device according to the first embodiment is also capable of performing a position disturbance of a specific angular frequency such as eccentric rotation of the magnetic disk by the operation of the disturbance estimator 14 and the corrector 15.
It is possible to further improve the positioning accuracy of the head.

Next, the compensator 1 when F (s) is not 1
Operation 5 will be described. In the block 71 of the compensator 15 shown in FIG. 2, when F (s) without a filter is 1, the transfer function Gd (s) expressed by the equation (7) is as follows. At times, it is deformed in the same way as when F (s) is 1. In that case, the transfer function Gd (s) is represented by the following equation (9).

[0041]

(Equation 9)

Therefore, F expressed by the following equation (10) is obtained.
Assuming that a filter having the characteristic of (s) is used for the block 71

[0043]

(Equation 10)

By substituting equation (10) into equation (9) and rearranging, the transfer function Gd (s) at this time is expressed by the following equation (11).
It is represented by

[0045]

[Equation 11]

In equation (11), the fractional part on the left side of the multiplication symbol on the right side is the angular frequency ωo according to equations (6) and (7).
A low-frequency cutoff filter characteristic capable of suppressing lower frequencies is shown, and a fractional part on the right side of the multiplication symbol on the right side shows a transfer characteristic of the notch filter with the notch angular frequency ωn and the damping factor ζn.

FIG. 6 shows a transfer function G represented by the equation (11).
It is a graph which shows the frequency characteristic of d (s). As shown in FIG. 6, the transfer function Gd (s) has a filter characteristic capable of suppressing an angular frequency lower than the natural angular frequency ωo and further significantly suppressing a specific angular frequency of the angular frequency ωn. I have. Therefore, in the disk device of the first embodiment, if the transfer characteristic of the filter F (s) of the block 71 is selected as expressed by the expression (10), the position disturbance xd due to the eccentricity in the rotation of the magnetic disk is as if the expression Acts as if it were added to the positioning control system through the filter having the cut-off frequency characteristic of (11) and FIG. Therefore, Example 1
In the disk device described above, position disturbance can be suppressed by the first-order low-frequency cutoff characteristic in the angular frequency range equal to or lower than the natural angular frequency ωo. Further, the disk device according to the first embodiment can obtain a significant positional disturbance suppression effect with respect to a positional disturbance at a specific angular frequency ωn.

Accordingly, the notch angular frequency ωn is changed to the angular frequency of the eccentric rotation of the magnetic disk 1 (for example, the magnetic disk 1
If the angular frequency of the eccentric rotation is set to 2π · 120 rad / sec in the case of 7200 rotations per minute, the tracking deviation due to the position disturbance xd at a specific angular frequency such as the eccentric rotation of the magnetic disk 1 can be suppressed. it can. As a result, the magnetic disk device of the first embodiment can improve the positioning accuracy of the head with respect to position disturbance such as eccentric rotation of the magnetic disk by the function of the disturbance estimator 14.

Embodiment 2 Hereinafter, Embodiment 2 according to the present invention will be described.
Will be described in detail with reference to FIGS. 7 and 8. FIG. FIG. 7 is a block diagram illustrating a configuration of a magnetic disk drive according to a second embodiment of the present invention. FIG.
FIG. 13 is a block diagram of a positioning control system in the magnetic disk device of the second embodiment. The components having the same functions as those of the magnetic disk device of the first embodiment are denoted by the same reference numerals, and the duplicate description will be omitted. In the magnetic disk drive of the embodiment shown in FIG. 7, the difference from the first embodiment is the signal input to the disturbance estimator. That is, the magnetic disk drive of the first embodiment
0 is generated by the disturbance estimator 14 and the drive signal u.
However, in the magnetic disk drive of the second embodiment, the error signal e generated by the position detector 10 and the control signal c generated by the position controller 11 are input to the disturbance estimator 24. Make up. The disturbance estimation signal Fd estimated by the disturbance estimator 24 of the second embodiment is input to the corrector 25. The adder 23 adds the control signal c output from the position controller 11 and the correction signal β generated by the corrector 25, and inputs the obtained drive signal u to the drive circuit 12.

In FIG. 8, the portion surrounded by the dashed line is
FIG. 3 is a block diagram of a disturbance estimator 24. Disturbance estimator 24
Includes an error signal e generated by the position detector 10 represented by the block 41 and the position controller 11 represented by the block 42.
Is generated. Example 1 described above
In the disturbance estimator 14 of the above, an adder 63 is necessary to input the drive signal u from which the correction signal β has been subtracted.
The acceleration estimation signal Aest obtained by multiplying the coefficient (1 / M) of the block 52 of the second multiplier and the signal obtained by multiplying the coefficient (g ₂ ) of the block 56 of the fourth multiplier by Is input to the block 53 of the first integrator. However, in the disturbance estimator 24 of the second embodiment,
Since the control signal c before the correction signal β is subtracted is input, an adder is not required. In FIG. 8, in the second embodiment, the block 58 constitutes a first multiplier, the combination of the blocks 51 and 52 constitutes a second multiplier, and the block 55 constitutes a third multiplier. . The block 53 constitutes a first integrator, and the block 54 constitutes a second integrator. In the disturbance estimator 24 according to the second embodiment, the first multiplier, the second multiplier, the third multiplier, the first integrator, and the second integrator are each configured by an analog filter. .

[Operation of the Disturbance Estimator 24] The operation of the disturbance estimator 24 in the magnetic disk device of the second embodiment configured as described above will be described with reference to the disturbance estimator 1 of the first embodiment.
4 will be described with reference to FIGS. 3 and 8. FIG. First, in FIG. 3, if the input signal of the integrator 53 constituting the disturbance estimator 14 of the first embodiment is τ, the signal τ
Is expressed by the following equation (12), focusing on the adder 63.

[0052]

(Equation 12)

However, the drive signal u is expressed by the following equation (13), focusing on the adder 13.

[0054]

(Equation 13)

Therefore, from the equations (12) and (13), the signal τ can be expressed by the following equation (14).

[0056]

[Equation 14]

Based on the equation (14), the first embodiment shown in FIG.
When the block diagram of the disturbance estimator 14 is rewritten, the block diagram becomes a block diagram of the disturbance estimator 24 shown in FIG.
As shown in FIG. 8, the control signal c of the position controller 11 is input to the multiplier of the block 51, and the output of the block 51 is input to the multiplier of the block 52. Therefore, the signal τ can be obtained by multiplying the control signal c by the coefficient (gm · Kf / M). On the other hand, the disturbance estimation signal Fd
Is input to the corrector 25 represented by block 72.
Therefore, as in the first embodiment, even if the position disturbance xd such that the target track meanders due to the eccentric rotation of the magnetic disk or the like acts on the positioning control system, this position disturbance xd
Is estimated by the disturbance estimator 24, and the disturbance estimation signal Fd is canceled so as to cancel the position disturbance xd.
act on d.

Accordingly, by inputting the disturbance estimation signal Fd to the corrector 25 of the block 72, the position disturbance x
d can be made to cancel each other, and similarly to the first embodiment, the natural angular frequency ω of the equations (6) and (7) can be used.
If o is set to be appropriately large, it is possible to suppress the tracking deviation of the magnetic head 2 from the target track due to the position disturbance xd. As a result, the magnetic disk device of the second embodiment can improve the positioning accuracy of the head even with respect to position disturbance such as eccentric rotation of the magnetic disk by the function of the disturbance estimator 24.

As described above, according to the magnetic disk drive of the second embodiment, the number of adders and multipliers required for the configuration of the disturbance estimator 24 can be reduced as compared with the magnetic disk drive of the first embodiment. . Therefore, it is possible to estimate the disturbance estimation signal Fd corresponding to the position disturbance xd acting on the positioning control system with a simpler configuration than the magnetic disk device of the first embodiment, and to achieve a head positioning accuracy with a simple configuration. Can be improved. Further, in the magnetic disk drive of the second embodiment, the number of adders and multipliers is reduced, so that when the positioning control system is realized by hardware such as an analog circuit, circuit adjustment can be simplified.
Further, when the positioning control system is realized by software, it is possible to reduce a calculation time delay due to calculation processing.

As described above, in the magnetic disk devices of the first and second embodiments, the input signal of the disturbance estimator is configured to input the control signal of the position controller, but the output signal of the drive circuit is used instead of the control signal. Needless to say, the same effect can be obtained even if a drive current signal is used. In each of the embodiments described above, the multiplier and the integrator are analog
Although the description has been made of the configuration using a filter, it is also possible to configure using a digital filter. Further, each unit constituting the positioning control system of each embodiment may be realized by software by a computer. In each of the embodiments described above, the magnetic disk device has been described. However, the present invention is not limited to this. For example, a position control system for a disk position disturbance such as an optical disk device or a magneto-optical disk device may be used. Can also be applied.

[0061]

As is apparent from the detailed description of the embodiments, the present invention has the following effects.
According to the disk device of the present invention, even if a position disturbance such that the target track of the disk meanders acts on the positioning control system due to the eccentric rotation of the disk or the like, a disturbance estimation signal corresponding to the position disturbance is generated by the disturbance estimator. And the disturbance estimation signal can be made to act so as to cancel the position disturbance. Therefore, even when high-order mechanical resonance exists in the actuator itself and the control band of the head positioning control system cannot be increased so much, the positioning accuracy of the head is further improved with respect to position disturbance such as eccentric rotation of the disk. It is possible to realize a large-capacity disk device by increasing the track density as compared with the related art.

Further, according to the disk device of the present invention, it is possible to improve the positioning accuracy of the head with respect to the position disturbance of a specific angular frequency such as the eccentric rotation of the disk by the functions of the disturbance estimator and the corrector. It is. Therefore, there is no need to provide a memory for storing eccentricity information for one rotation of the disk or a sine wave generator for generating a sine wave having the same fundamental frequency as the rotation speed of the disk. As a result, it is possible to realize a disk device having a high positioning accuracy even with respect to the eccentricity of the disk with a view to increasing the track density without hindering downsizing and cost reduction of the device.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a positioning control system in the magnetic disk drive of Embodiment 1 according to the present invention.

3A is a block diagram of a disturbance estimator 14 included in the block diagram of FIG. 2, and FIG. 3B is a block diagram simply representing the block diagram of the disturbance estimator 14 of FIG. FIG.

4A is a block diagram illustrating the operation of a corrector included in the block diagram of FIG. 2, and FIG.
FIG. 4 is a block diagram of an input unit for displacement due to position disturbance in FIG.

FIG. 5 is a graph showing frequency characteristics when F (s) = 1 with respect to a position disturbance applied to the magnetic disk device of the first embodiment according to the present invention.

FIG. 6 is a graph showing frequency characteristics when F (s) 1 is applied to a position disturbance applied to the magnetic disk device of the first embodiment according to the present invention.

FIG. 7 is a diagram illustrating a configuration of a magnetic disk drive according to a second embodiment of the present invention.

FIG. 8 is a block diagram of a positioning control system in a magnetic disk drive according to a second embodiment of the present invention.

FIG. 9 is a graph showing a frequency characteristic of a transfer characteristic of a displacement of a head from a drive input of an actuator in a conventional magnetic disk drive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Magnetic head 4 Bearing 7 Actuator 10 Position detector 11 Position controller 12 Drive circuit 14 Disturbance estimator 15 Corrector

Claims (8)

[Claims] A head for recording / reproducing data on / from a disk; an actuator for receiving a drive signal to move the head to a position facing a target track on the disk; and supplying a drive power to the actuator. Drive means, position detection means for generating and outputting an error signal corresponding to the current position of the head from servo information of the disk detected by the head, position control means for generating and outputting a control signal corresponding to the error signal A disturbance estimating means for estimating a magnitude of a position disturbance applied to the head from the error signal and the drive signal, and outputting a disturbance estimation signal; correcting a signal of a specific frequency in the inputted disturbance estimation signal to generate a correction signal; Correction means for outputting, and addition means for generating and outputting a drive signal from the control signal and the correction signal. Disk apparatus characterized by. 2. The disturbance estimating means includes: first multiplying means for multiplying an error signal generated by the position detecting means by a first coefficient; comparing means to which an output of the first multiplying means is input; Second multiplying means for multiplying the drive signal generated by the adding means by a second coefficient, third multiplying means for multiplying the output of the comparing means by a third coefficient, and a fourth coefficient for the output of the comparing means. A first integrating means for integrating an added value of an output of the second multiplying means and an output of the fourth multiplying means, and an output of the first integrating means and the output of the first integrating means. A second integrating means for integrating an added value with an output of the third multiplying means, wherein the comparing means compares an output of the first multiplying means with an output of the second integrating means, 2. The apparatus according to claim 1, wherein the result is output to a third multiplier and a fourth multiplier. The disk device as described above. 3. The correction means uses the following equation (1). (Where s is a Laplace operator, ζn and ζo are predetermined positive constants, ωn is an angular frequency corresponding to a specific frequency to be corrected by the correction unit, and ωo is an angle corresponding to a high cutoff frequency of the disturbance estimation unit. 2. The disk device according to claim 1, having a transfer function calculated by: 4. The disk device according to claim 1, wherein the specific frequency of the correction means is set to be equal to the eccentric frequency of the disk. 5. A head for recording / reproducing data to / from a disk, an actuator for receiving a drive signal and moving the head to a position facing a target track of the disk, and supplying drive power to the actuator. Drive means, position detection means for generating and outputting an error signal corresponding to the current position of the head from servo information of the disk detected by the head, position control means for generating and outputting a control signal corresponding to the error signal A disturbance estimating unit that estimates a magnitude of a position disturbance applied to the head from the error signal and the control signal, and outputs a disturbance estimation signal; a correction unit that receives the disturbance estimation signal and outputs a correction signal; A summing means for generating and outputting a drive signal from a signal and the correction signal. Location. 6. A disturbance estimating means, a first multiplying means for multiplying an error signal generated by the position detecting means by a first coefficient, a comparing means to which an output of the first multiplying means is inputted, Second multiplying means for multiplying the signal by a second coefficient, third multiplying means for multiplying the output of the comparing means by a third coefficient, first integrating means for integrating the output of the second multiplying means,
And a second integrating means for integrating an added value of an output of the first integrating means and an output of the third multiplying means, wherein the comparing means includes an output of the first multiplying means and the second integrating means. 6. The disk device according to claim 5, wherein the output is compared with the output of the integrating means, and the result is output to the third multiplying means. 7. The disk device according to claim 1, wherein the disturbance estimating means is configured to cut off high frequency components and output a disturbance estimation signal. 8. The disk device according to claim 1, wherein a cutoff frequency of the disturbance estimating means is configured to be higher than an angular frequency due to eccentricity of the disk.