JPH0330156A - Disk device - Google Patents

Abstract

PURPOSE:To perform external force correction with high accuracy and to contrive improvement of head positioning accuracy and curtailment of access time by providing an external force estimating means, a storage means for storing external force estimating value and a correction means for correcting a position control signal by the stored external force estimating value. CONSTITUTION:Since a position signal is deviated from zero by an offset amt. of a head as well when the head is pulled by external force, the position signal is fetched as a sample position signal through an A/D converter 9 by a digital compensator to be executed in a controller 15, and compensation is carried out to make this signal zero. That is, a phase compensating calculation of phase-lead-lag compensation, etc., or a state feedback compensating calculation including a state estimator is performed on the sample position signal by the digital compensator, and a sample control signal obtained by adding up this calculation result and the external force correction value is inputted via a D/A converter 7 to a driving circuit 6, so as to make the magnetic head 3 follow the center of a track. By this method, since the external force can most suitably be compensated, the improvement of the positioning accuracy and the curtailment of the access time are contrived.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a head positioning method for optical or magnetic disk devices, and in particular realizes a method for canceling variations in external force of the device, thereby improving head positioning accuracy. The present invention relates to a disk device that can reduce access time.

[Conventional technology]

Conventional disk devices For example, in magnetic disk devices, the magnetic head generally flies as the rotational speed of the disk increases.In order to protect the data storage area, the head is moved to the data area when starting and stopping. It is necessary to position it outside of the Generally, the head is positioned at the innermost part of the movable part by pulling the actuator in one direction with a spring called a retract spring, but as the track density becomes narrower and the actuator becomes lighter, external force is applied to the positioning control system. The impact is significant, and it is common practice to compensate for it.

In the conventional external force compensation method, compensation was initially performed using a constant value over the entire track range. Next, a method was proposed in which correction values are output for each track between the inner track and the outer track. However, with such a method of compensation using a uniform external force correction table, it is not possible to compensate for variations in devices or the influence of gravity when the mounting direction changes. Therefore, for example, as described in JP-A-59-146485 and JP-A-59-146486, the estimated speed signal and the error signal between the speed signal, or the estimated current signal and the error signal between the current signal, are converted into analog There is also a method of compensating by feeding back the signal and adding it to the input of the power amplifier as a disturbance cancellation signal, and a method of compensating for the disturbance by feeding it back using a method of
A method has been proposed in which the amount of displacement is measured by an A/D converter and the correction value is updated.

[Problem to be solved by the invention]

With the increase in capacity and speed of disk drives, the track width has become narrower and the weight of the actuator has been significantly reduced, but as a result, the influence of external forces applied to the actuator has become increasingly impossible to ignore.

Conventional external force measurement methods include estimating the current or speed and feeding back the error signal between the estimated signal and the detection signal using an analog method, or modifying the external force correction value by looking at the displacement signal. There was one way or another.

However, with the method of feeding back the estimated error signal using an analog method and correcting the external force in real time, the frequency of the external force is low, so when switching to a control system that positions and holds the magnetic head, a transient response may occur. The problem is that it takes a long time.

In addition, the method of setting the external force correction value from the displacement signal has a problem with the accuracy of the measured external force correction value. The purpose of the present invention is to improve these conventional problems and to improve head positioning accuracy and shorten access time by performing highly accurate external force correction without being affected by mounting direction or device variations. The objective is to provide a disk device that is possible.

[Means to solve the problem]

In order to achieve the above object, the servo control system for a disk device according to the present invention uses a sample position signal obtained by AD converting the output of a position detector and a DA The sample control signal output to the drive circuit via the converter is input to the external force estimating means implemented on the microprocessor system, and the external force estimating means adds the estimated external force correction value to the digital servo compensation result. By doing this, external force can be compensated for.Furthermore, for each normal operation after the controller is powered on, external force correction values for multiple tracks representing the disk are measured from the output of the external force estimator, and external force correction is performed. Stored as a table in memory within the microprocessor system,
The external force correction table described above is used for subsequent external force correction.

In addition, in an analog servo control system realized by an analog circuit, an AD converter for converting a position signal output from a position detector into a sample position signal;
An AD converter that converts a control signal input to a drive circuit into a sample control signal, a microprocessor system that realizes an external force estimation means that estimates and calculates an external force correction value from these sample position signals and sample control signals, and an external force estimation device. DA that converts the external force correction value that is the output of the device into an analog signal
A converter and an addition means for adding the external force correction value to the analog compensation calculation result are provided, and the external force correction value is added to the analog compensation calculation result for each normal operation after the power is turned on. A correction value is measured from the output of the external force estimator and stored in a memory within the microprocessor system as an external force correction table, and the external force correction table is used for subsequent external force corrections.

[Effect]

The outer force estimating means of the disk device according to the present invention includes an observer for estimating position and velocity. When no external force is acting on the actuator, the estimated position signal and the sampled position signal should match.

The reason why they do not match is due to the presence of a disturbance, that is, an external force, and the external force can be compensated for by amplifying the error between the estimated position signal and the sampled position signal and outputting it as part of the control signal. Furthermore, when the external force estimated value obtained here is settled, it is stored in the memory within the microprocessor system as an external force correction value.

By the way, as mentioned above, the external force applied to the actuator is not only caused by the retract spring but also by the F P that exchanges signals with the movable part of the actuator.
C (Flexible Printed Circ
The external force acting on the inner track is different from the external force acting on the outer track due to the influence of a flexible polymeric material called UIT and the wind pressure caused by the rotation of the disk. Therefore, in the present invention, by using the external force estimating means described above to obtain external force correction values on a plurality of tracks representing the disk, and by interpolating these plurality of external force correction values, the external force correction value is calculated over the entire track area. It is possible to obtain Of course, it is also possible to obtain external force correction values for all tracks.

The external force correction values obtained as described above are stored in an external force correction table, and subsequent external force corrections are performed using the external force correction table. As a result, since it does not take time to estimate external force, the positioning settling time is short, which is a feature of the present invention. Embodiment] [First Embodiment] An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a simplified block diagram of a magnetic disk device showing one embodiment of the present invention.

In the microprocessor system 10 of FIG.
Microprocessor 11 via data bus 14
It is connected to random access memory (RAM) 12 and read only memory (ROM) 13. The controller 15 issues a command to the microprocessor l1 to move to an arbitrary track.

Further, a disk 2 is mounted on the drive spindle 1, and a magnetic head 3 is provided on this disk 2.

The magnetic heads 3 are fixed to an actuator 4 and can be moved as a group to any desired track. The actuator 4 uses the current generated by the drive circuit 6 to cause the magnetic head to perform a linear motion proportional to the current.

On the other hand, the actuator 4 is affected by an external force such as the retract spring 5.The position detector 8 uses the servo information read from the magnetic head 3 to generate a position signal that becomes zero at the center of the track. Occur. When the head is pulled by an external force, the position signal also deviates from zero by the amount that the head is offset, so the digital compensator executed in the controller 10 takes the position signal as a sample position signal in the AD converter 9 and adjusts the position signal to zero. Compensate accordingly. In other words, the digital compensator performs phase compensation calculations such as phase lag/lead compensation or state feedback compensation calculations including a state estimator on the sample position signal, and generates a sample control signal by adding the result of this calculation and the external force correction value. is input to the drive circuit 6 via the DA converter 7, and the magnetic head 3 is caused to follow the track center.

Next, an explanation will be given of the present invention in which an optimal external force correction value is determined and stored in an external force correction table as part of the initial sequence. The simplified block diagram of FIG. 1 is intended to illustrate the hardware necessary to implement a digital servo control system. Therefore, the operation of the initial sequence will be explained with reference to FIG. In Figure 1. 1! The input gain K1 [N
/Vl 23. Also, the magnetic head 3 has a mass M
[: kgl pure inertial mass 24]. If this is expressed as a transfer function, it becomes 1/(MS"). However, S represents the Laplace operator. Also, it is assumed that the position detector 8 can be expressed as an output gain KzCV/m]25. The digital compensator 18 and the external force estimator 19 implemented in the processor system 10 are implemented by the microprocessor 1
1, RAM 12, and ROM 13 are implemented by software, so each is described as one block in Fig. 2. Next, the initial sequence for measuring the external force correction value will be explained using the flowcharts of FIGS. 1 and 2, and FIGS. 3 and 4. However, for the sake of simplicity, a case where the external force correction value is measured at three locations will be described.

After turning on the power, wait until the drive spindle 1 reaches a certain rotational speed and starts normal operation (see the flowchart in Figure 3).
100). Next, in the microprocessor system 10, the inner track is set as the target track (101 in the flowchart of FIG. 3), the target track is moved (seek), and after the movement is completed, the external force estimator 19 is activated, and the external force correction value is Optimize (Flowchart 102 in Figure 3).
The operation of optimizing the external force correction value will be explained using the flowchart of FIG. 4. First, the microprocessor system 10 connects the software switch 22 to the speed controller 17.
side, move the software switch 20 to the external force correction table 1.
6 side, and moves (seeks) the magnetic head 3 to the target track (FIG. 4 flowchart 200). However, although the external force correction table 16 exists in the RAM 12, since the operation is performed before external force measurement, standard values prepared in advance in the ROM 13 are written in the external force correction table 16 in the RAM 12. Next, when the target track is near, the software switch 22 is switched to the digital compensator 18 side, and the software switch 20 is switched to the external force estimator 19 side.
side, the external force estimator 19 is operated to cause the magnetic head 3 to follow the center of the track (Fig. 4 flowchart 2).
01).

The operations of the digital compensator 18 and the external force estimator 19 will be described later. Next, the process waits until the estimated external force value, which is the output of the external force estimator 19, is stabilized. For example, the time it takes for the disk 2 to rotate l (when it rotates at 3600 rpm),
1 6. 7 msec), wait for the estimated external force to settle. At the stage of settling, the estimated external force value is stored in the external force correction table l6 (flowchart in FIG. 4, 202).

Similar operations are performed on the middle track and the outer track (Flowchart in Figure 3: 103, 104, 105,
Engineering 06). Next, the external force correction values for the inner, middle, and outer circumferences are interpolated to obtain the external force correction value for the entire track, and written to the external force correction table l6 (Flowchart 107 in Figure 3).
. Finally, the microprocessor 1l reports the completion of the operation to the controller 15 and enters a command input waiting state.

External force correction in subsequent operations is performed using an external force correction table that stores optimal external force correction values, so it is possible to perform optimal external force correction that is not affected by variations in external force for each device or the mounting direction. Next, the digital compensator l8 will be explained.

Although the digital compensator l8 can be realized by state feedback compensation including a state estimator, in this embodiment, 5 phase delay and lead compensation is used. Digital compensator 18 at this time
The discrete transfer function of is expressed as . However, Z-1 is 1
Indicates sample delay, aXH aae biy b2.
tba represents a constant representing the frequency characteristics of the digital compensator 18. This is the loop gain of the Ko digital compensator 18. To the digital compensator 18, the target value r(k)
The deviation signal e obtained by subtracting the sample position signal y(k) from
(k) is input, and the digital compensation calculation result v(k) is output. where k represents the time index of each digital sample. The output equation for obtaining the digital compensation calculation result v(k) from the deviation signal e(k.) is shown below: Wa(k)''b se(k)+Wt(k)
−(2)v(k)=Kc−Wa(k)
- (3) The digital compensation calculation result v(k) is obtained by equation (3), but in order to obtain v(k) also in the next sample, after outputting the sample control signal u(k), the next Wl, Calculate state variables such as W2. Wx
．． Wz is as follows.

Wz(k+1)=Wz(k)+bz・e(k)−az・
W2I(k)...(4) Wz(k+1)=ba・e(k)−arWs(k)
・=(5) The external force estimator 18 is configured to control the control target (FIG. 2 23,
24.25) consists of a discrete time observer that estimates the position and velocity of the The sample control signal u(k) and the sample position signal y(k) are input to the external force estimator 19, and the external force estimator 19 outputs an estimated external force value W(k).

However, the sample control signal u (k) is input to calculate the estimator state variables Xi, X2 corresponding to position and velocity. The external force estimator l9 first obtains an estimated external force value W(k) from the sample position signal y(k) using the following equation.

y(k)=Kz・xt(k)
...(6) e (k) = y (k) − y
(k) ... (7) W(k)=-H
-e (k) -(8) However, H = (M-Q z)/ (Kl ・Ts)
- (9) is a gain for canceling external force in a steady state, Q2 is a feedback gain of the external force estimator 19 described later, and Ts is a sampling interval. Also, sample for the next sample!
After outputting the II control signal u(k), calculate the next state equation time.

+Ql-e(k) ...(10)K
1・Ts" rz (k + 1)=-・u (k)+Q 2-e
(k)M...(11) However, Qx. Q2 is a feedback gain that determines the speed of convergence of the external force estimator.

On the other hand, the sample control signal u(k) is expressed by equation (3) and (8).
From the formula u (k) = v (k) + W (k)
...(12) is calculated.

Next, the calculation procedure described above will be explained using the flowchart shown in FIG. First, a sample position signal is fetched from the AD converter 9 and inputted to y(k) (300 in the flowchart of FIG. 5). Next, output equation group (2). (3)
, (6), (7), (8), (12) are calculated (Fig. 5 flow chart 3 0 1), (12
) The sample control signal u(k), which is the result of the equation, is output to the DAl converter 7 (302 in the flowchart of FIG. 5). Finally, for the next sample, state equations (4), (5
), (10), and (11) are calculated.

[Second example] Other embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 6 is a simplified block diagram of a magnetic disk device showing one embodiment of the present invention. In FIG. 6, the same numbers as in FIG. 1 indicate the same contents.

This embodiment is a servo system in which an analog servo control system and a digital servo control system are mixed. The compensator 30 is an analog compensation element, and may be a state feedback compensation element including a state estimator or a phase compensation element. In this embodiment, we will take the perspective of phase compensation and explain it using phase lead/lag compensation elements.

The transfer function of the compensator 30 that performs phase lead/lag compensation is expressed as follows. However, does S indicate the Laplace operator? ,a
■、a3、bt、bxe ba is compensation! Kc is a constant representing the frequency characteristics of the compensator 30, and Kc represents the loop gain of the compensator 30. The compensator 30 generates a deviation signal e (=
ry) is input, the compensation calculation of equation (13) is performed,
The compensation calculation result V is output.

The adder 34 adds the compensation calculation result V and the external force correction value W, which is the output of the external force correction DA converter, and outputs the control signal U, which is the addition result, to the freezing circuit 6.

The drive circuit 6 supplies a current proportional to the control signal U to the actuator 4, and controls the magnetic head 4 to follow the track center without being affected by external force.

The microprocessor system 10 includes a microprocessor 11. It is composed of a RAM 12, a ROM 13, and a data bus 14, and takes in the sampled control signal u(k) sampled by the control signal ui2AD converter 32 and the sampled position signal y(k) obtained by amplifying the position signal y by the AD converter 9. , the external force correction value W(k) is obtained by the external force estimator in the microprocessor system 10, stored in the external force correction table in the RAM 12, and further, the external force correction DA converter 3
1, the external force correction value W(k) is output.

Next, as part of the initial sequence, finding the optimal external force estimate and storing it in the external force correction table will be explained. Microprocessor system 10 in FIG. 6 shows the hardware necessary to implement a digital servo control system. Therefore,,
The operation of the initial sequence is shown in Figures 6 and 7, and Figures 3 and 8, which are the float yachts used in the first embodiment.
This will be explained using FIG. 9 and FIG. However, in FIG. 7, the same numbers as in FIG. 2 indicate the same contents.

However, for the sake of simplicity. A case where the external force correction value is measured at three locations is described.

After turning on the power, wait until the drive spindle 1 reaches a certain rotational speed and starts normal operation (see the flowchart in Figure 3).
100). Next, in the microprocessor system 10, the inner track is set as the target track (101 in the flowchart of FIG. 3), the target track is moved (seek), and after the movement is completed, the external force estimator 19 is activated, and the external force estimator 19 is activated. The correction value is optimized (102 in the flowchart of FIG. 3). The operation of optimizing the external force correction value will be explained using the flowchart shown in FIG. First, the microprocessor system 10 connects the analog switch 35 to the speed controller 33.
side, move the software switch 20 to the external force correction table 1.
6 side and move it to the target track (Flowchart 400 in FIG. 8).

However, although the external force correction table 16 exists in the RAM 12, the mm value prepared in advance in the ROM 13 is written in the external force correction table 16 in the RAM 12 because the operation is performed before external force measurement. Next, when near the target track, the analog switch 35 is set to the compensator 30 side, the software switch 20 is set to the external force estimator 19 side, the external force estimator 19 is operated, and the magnetic head 3 is caused to follow the center of the track ( Figure 8 flowchart 401).
The operation of the external force estimator 19 is shown in the flowchart of FIG.

The external force estimator 19 inputs the sample control signal u(k) from the AD converter 32, and further inputs the sample position signal y(k) from the AD converter 9 (see the flowchart in FIG. 9).
501) = Calculate the output equation group (6), (7), and (8) (Flowchart in Figure 9, 502). (8
) is the result of the external force estimated value W(k), which is the external force correction value DA.
Output to converter 31 (Fig. 9 flowchart 503
), then the external force estimator 9 calculates the state equation group (10) and (11) in preparation for the next sample (
FIG. 9 flowchart 504). Next, wait until the external force estimate W(k), which is the output of the external force estimator 9, is stabilized. For example, the period during which the disk 2 rotates l (3 6 0 0
When rotating at rpra, wait for the estimated external force to settle for 16.67 msec). At the stage where it is settled, it is stored in the external force correction table 16 (Fig. 8 flowchart 4)
02). Similar operations are performed on the middle track and the outer track (flowchart in Figure 3, 103, 104.
．． 105, 106).

Next, the external force correction values for the inner, middle, and outer circumferences are interpolated to obtain the external force correction values for the entire track and stored in the external force correction table 16 (flowchart 107 in FIG. 3). lastly,
The microprocessor 11 reports the completion of the operation to the controller 15 and enters a command input waiting state (108 in the flowchart of FIG. 3).

External force correction in subsequent operations is performed using an external force correction table that stores the optimal external force correction values, so it is possible to perform optimal external force correction that is not affected by variations in external force for each device or the mounting direction. [Third Embodiment] Another embodiment of the present invention will be described in detail with reference to FIGS. 10 and 11. As described in the first and second embodiments, in a magnetic disk device, by measuring the external force correction value after power is turned on, changes in the external force value due to variations in the external force of the device or changes in the mounting direction can be detected. However, due to changes in external force over time after the power is turned on, for example, due to a rise in the temperature of the device, the retract spring or FPC (Flexi
In the first and second embodiments, changes in external force due to changes in the spring force of the printed circuit or changes in the offset of the electric circuit system cannot be absorbed. Therefore, in this embodiment, in the magnetic disk drive shown in the construction drawing and FIG. 6, as shown in the flowchart of FIG. This method attempts to absorb changes in external force over time by repeating the measurement of the external force correction value performed in the initial sequence. This will be explained below using Fig. 10 and the first engineering drawing. First of all, in order to control fixed time intervals, a variable TI that increases at a constant rate over time
After the ME is placed in the controller 15 and the power is turned on, the variable TIME is cleared to zero (600 in the flowchart of Fig. 10). Next, the controller 15 issues an initial sequence command to the microprocessor 11 to measure the external force correction value throughout the trunk (
FIG. 10 Flowchart 601). Next, the controller 15 monitors changes in the variable TIME and maintains a constant value PER.
Wait until IOD (Fig. 1O flowchart ゜60)
2) When the variable TIME becomes equal to or greater than the fixed value PERIOD (Flowchart in Figure 10, if 602 is YES)
, the controller 15 issues a command to the microprocessor 1l to re-measure the external force correction value (603 in the flowchart of FIG. 10).

Next, in preparation for the next re-measurement, the controller 5 clears the variable TIME to zero (Flowchart 6 in Figure 10).
04), wait for the report of the completion of re-measurement of the external force correction value of the microprocessor 11 (Flowchart 60 in Figure 10)
5). On the other hand, the microprocessor 11 receives the re-measurement command and starts re-measuring the external force correction value, as shown in the flowchart of FIG. The procedure is similar to the initial sequence, setting the target value on the inner track and optimizing the external force correction value (see flowchart 7 in Figure 11).
00,701).

The operation of optimizing the external force correction value is executed according to the flowchart of FIG. 4 in the case of the magnetic disk drive of FIG. 1, and according to the flowchart of FIG. 8 in the case of the magnetic disk drive of FIG. 6. Similar operations are performed on the middle and outer peripheries of the disk 2 (Fig. 11 flowchart, 702, 703, 7
04, 705), and by interpolating the external force correction value based on the obtained external force correction value, the external force correction value for the entire track is determined and stored in the external force correction tail (706 in the flowchart of FIG. 11). Finally, the microprocessor l1 reports the completion of the remeasurement command to the controller 15.

As described above in this embodiment, by correcting the external force correction table at regular time intervals, it is possible to obtain a magnetic disk device that is resistant to changes in external forces over time.

[Fourth Embodiment] Another embodiment of the present invention will be described in detail with reference to FIGS. 10 and 12.

A simpler method for correcting the external force correction value due to changes in external force over time in a magnetic disk drive is to correct only the offset of the external force. Comparing the method of measuring the external force correction value from several locations on the disk at fixed time intervals, it is easier to correct the external force correction table based on a deviation in the external force correction value at one location, Overall, throughput can be improved.
As shown in the third embodiment, after the initial sequence measures the external force correction value over the entire track and creates an external force correction table (601 in the flowchart of Fig. 10), after a certain value PERIOD has elapsed ( The external force correction value re-measuring routine as shown in the flowchart of FIG. 10 (602) and FIG. 12 is similarly performed in this embodiment. In the initial sequence, the current external force correction value for a certain track
(Fig. 12 flowchart 800). Next, X is set as the target track, and the external force correction value W on the X track is determined by the external force correction value optimization routine (801 and 802 in the flowchart of FIG. 12). thus,
From the new external force correction value W and the external force correction value WOLD before the time PERIOD, the change over time of external force DELT (=W-WO
LD) is measured (Fig. 12 flowchart 803
6). Finally, by adding the external force change amount DELT over time to the external force correction values on other tracks, the external force correction value for the entire track is obtained and stored in the external force correction table, and when the time period PERIOD has elapsed, Repeat the process of correcting the external force correction table again. According to this embodiment, the external force correction value can be corrected in a very short time, which is very effective for system operation of the magnetic disk drive.

In the above-described embodiments, a magnetic disk device was used, but it goes without saying that the present invention can be similarly implemented using other recording media, such as optical disks.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to measure external force with high precision and compensate for it optimally, thereby making it possible to improve positioning accuracy and shorten access time.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the hardware of a magnetic disk device showing one embodiment of the present invention, Fig. 2 is a control system configuration diagram showing the present invention, and Figs. It is a flowchart for explaining one example. 6 and 7 are block diagrams of a magnetic disk device showing a second embodiment of the present invention. 8 to 12 are flowcharts for explaining the operation of the present invention. ↓... Drive spindle, 2... Disc, 3... Magnetic head, 4... Actuator, 5... Retract spring, 6... Drive circuit, 7... DA converter, 8...・・・
Position detector, 9... AD converter, 10... Microprocessor system, l1... Microprocessor,
12...RAM, 13...ROM, 14...Data bus, 15...Controller, 16...External force correction table, 17...Speed controller, Engineering 8...Digital compensator, l9 ...External force estimator, 2o...Software switch, 22...Software switch, 23.
... Input gain, 24 ... Pure inertial mass, 25 ... Output gain, 30 ... Compensator, 31 ... External force correction D
A converter, 32...AD converter, 33...speed controller, 35...analog switch. Naotsu (2) Ka5 Eye 6 8 Figure 6 9 Kume/O Eye envy 11 Trouble

Claims (1)

[Claims] 1. A disk having servo information, a head for reading the servo information from the disk, a position detecting means for determining a position signal from the center of the track from the read servo information, and a target position. a calculation unit that calculates and outputs a position control signal for reducing the difference between the calculated position signal and the calculated position signal;
A disk device including: an adjusting means for adjusting the position of the head according to the position control signal; an external force estimating means for estimating an external force correction value using the position signal; and a storage means for storing the estimated external force value. A disk device comprising: a correction means for correcting the position control signal based on the stored estimated external force value. 2. The disk device according to claim 1, wherein the arithmetic unit, the external force estimation means, the storage means, and the correction means are constituted by one microprocessor system. 3. In claim 1, the external force estimating means performs an estimation calculation every time the disk device starts normal operation after power is turned on, and the storage means rewrites the external force correction value with a new external force correction value every time the estimation calculation is performed. A disk device characterized in that: 4. Information is stored or recorded by a magnetic head attached to an actuator that is movable in the radial direction of the magnetic disks while a plurality of magnetic disks are mounted on the same shaft and are rotated. A magnetic disk device configured to reproduce information, comprising a position detection means for detecting the position of the magnetic head, and a control signal for moving the position of the magnetic head closer to a target position using the position signal. and a calculation control means for calculating the signal and supplying the signal to the actuator,
The calculation control means estimates and calculates an external force correction value at the start of operation of the magnetic disk device, and stores this external force correction value as a table, and stores the external force correction value until it is updated thereafter. A disk device characterized in that the control signal supplied to the actuator is corrected using an external force correction value. 5. The device is configured to use the deviation between the output of the head position detection means on the magnetic disk surface and the target position to control the position of an actuator equipped with the head in accordance with a control signal that reduces the deviation. In the disk device, inputting the output of the position detecting means and estimating an external force correction value,
Compensating means for storing and holding this value until the next update and outputting the stored external force correction value; and adding means for correcting the control signal by adding the output of the compensating means and the control signal. A disk device characterized in that: 6. The disk device according to claim 5, wherein the compensating means is a microprocessor. 7. A disk having servo information that defines the center line of the data track, a magnetic head that reads the servo information from the disk, and a position detector that generates a signal (position signal) indicating the position from the center of the track. , an actuator to which the magnetic head is fixed, a drive circuit that drives the actuator, an AD converter that receives the position signal and converts it into a digital value, and a sample position signal that is the output of the AD converter that is fed back. , Realization of a digital compensator that performs digital compensation calculation so as to follow the center of the track, and an external force for compensating the external force that is the sum of the mechanical external force acting on the actuator and the electrical offset and drift occurring in the drive circuit. A microprocessor system for storing correction values according to track numbers of the disc, and a sample control signal obtained by adding the digital compensation calculation result output from the digital compensator and the external force correction value to an analog signal. External force estimating means for calculating the external force correction value as a function of the sample control signal and the sample position signal in a magnetic disk device equipped with a DA converter for converting and outputting the converted signal to a drive circuit, and a controller for controlling the entire device. is provided in the microprocessor system, and each time the magnetic disk device starts normal operation after power is turned on, the external force estimation means calculates the external force correction value on a plurality of representative tracks on the disk; Further, an external force correction value for the entire track area is obtained by interpolating the external force correction values for the plurality of tracks, the external force correction value is stored in a memory in the microprocessor system, and subsequent external force corrections are performed using the external force correction value. A disk device characterized in that correction is performed using a correction value. 8. A disk having servo information that defines the center line of the data track, a magnetic head that reads the servo information from the disk, and a position detector that generates a signal (position signal) indicating the position from the center of the track. , an actuator to which the magnetic head is fixed, a drive circuit that drives the actuator, a compensator that feeds back the position signal and performs compensation calculation so as to follow the track center, and an external mechanical force that acts on the actuator. and a microprocessor system for storing an external force correction value for compensating for an external force that is the sum of electrical offsets and drifts occurring in the drive circuit, according to the track number of the disk;
a DA converter in the microprocessor system for converting the external force correction value into an analog value; and an adder for adding the external force correction value converted to the analog value to the compensation calculation result that is the output of the compensator. , in a disk device equipped with a controller that controls the entire device, an AD converter that converts a control signal output from the adder into a digital value, and an AD converter that converts the position signal into a digital value, Furthermore, the external force correction value is
An external force estimator that calculates as a function of a sample control signal and a sample position signal, which are the outputs of the D converter, is provided in the microprocessor system, and every time the magnetic disk device starts normal operation after power is turned on, The external force correction value is determined by the external force estimator on a plurality of representative tracks, further, the external force correction value for the entire track is determined by interpolating the external force correction value for the plurality of tracks, and the external force correction value is determined by interpolating the external force correction value for the plurality of tracks. is stored in a memory within the microprocessor system, and subsequent external force correction is performed using the external force correction value. 9. In the disk device according to claim 1, the external force estimator calculates external force correction values for a plurality of representative tracks on the disk after the power is turned on and at fixed time intervals after the power is turned on; The external force correction value and the external force correction value obtained by interpolating the external force correction value over the entire track are stored in the memory in the controller, and the external force correction value is used for the external force correction value until the next time the external force correction value is changed. A disk device characterized by: 10. In the disk device according to claim 8, the external force estimator calculates external force correction values for a plurality of representative tracks on the disk after the power is turned on and at fixed time intervals after the power is turned on; The external force correction value and the external force correction value obtained by interpolating the external force correction value over the entire track are stored in the memory in the controller, and the external force correction value is used for the external force correction value until the next time the external force correction value is changed. A disk device characterized by: 11. In the disk device according to claim 7, the external force estimator calculates an external force correction value on one track representing the disk at fixed time intervals after the power is turned on, and the external force correction value is calculated by the external force estimator. A disk device characterized in that the external force correction value for the entire track stored in the memory is shifted and re-stored by the difference between the external force correction value for the track and the external force correction value for the track previously stored in the memory. 12. In the disk device according to claim 8, the external force estimator calculates an external force correction value on one track representing the disk at fixed time intervals after the power is turned on, and the external force correction value is calculated by the external force estimator. A disk device characterized in that the external force correction value for the entire track stored in the memory is shifted and re-stored by the difference between the external force correction value for the track and the external force correction value for the track previously stored in the memory.