JPH02239476A - Servo circuit adjusting method for magnetic disk device - Google Patents

Abstract

PURPOSE:To exactly execute automatic adjustment by starting the seek drive of a servo circuit in correspondence to the detection of an index signal, measuring the operation of the servo circuit by the seek drive and determining an adjusted value. CONSTITUTION:The adjusted value is applied to a servo circuit CT and in correspondence to the detection of the index signal from the output of a servo head 1b, the seek drive of the servo circuit CT is started. Then, the operation of the servo circuit CT is measured based on the output of the servo head 1b by the seek drive and the adjusted value is determined based on the result of this measurement. Accordingly, the operation can be always measured based on the output of the servo head 1b in the same position of an index. Thus, even when the servo track write on a servo surface is dispersed in each adjustment, the operation can be measured in the same position from the index and the automatic adjustment can be exactly executed.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 14) Means for solving the problems to be solved by the invention (Figure 1) Working examples (a) Section Description of 10 Examples (Figures 2 to 7) (b
) Description of the second embodiment (Figures 8 to 13) (C)
Description of Other Embodiments Effects of the Invention [Summary] The present invention relates to a servo circuit adjustment method for automatically adjusting a length circuit that performs a head seek operation in a magnetic disk device. In a magnetic disk drive including a servo head that reads a disk O servo surface, a drive source that drives the servo head, and a servo circuit that drives the drive source in a seek manner based on the output K of the servo head, adjustment is made to the cough servo circuit. and detects an index signal from the output of the servo head, starts seek drive of the l* servo circuit, and operates the servo circuit based on the output of the servo head due to the seek drive. The adjustment value is determined based on the measurement result.

[Industrial application field]

The present invention relates to a servo circuit adjustment method for automatically adjusting a servo circuit that performs a seek operation on a head in a magnetic disk drive.

In a magnetic disk drive, a servo head reads servo information on a servo surface of a magnetic disk, converts this into a position signal K, and a servo circuit servo-controls a voice coil motor to perform a seek operation.

In such a servo circuit, various OPS* are required depending on circuit offset, variation in core width of the servo head, etc., and automatic adjustment technology is desired. [Conventional technology] Figure 14 shows the conventional technology FIG.

In Fig. 14K, la is a boil coil motor that is a drive source and performs seek operation on the magnetic head, lb is a servo head (magnetic head), and magnetic disk 1c.
This is to read the servo information on the O servo surface.

Reference numeral 2 denotes a position signal generation circuit, which generates a position signal from the read signal of the servo head 1b.

3a is a speed detection circuit, which detects the actual speed Vr from the position signal Ps and a detection voltage iIc, which will be described later. 3b is a speed error detection circuit, which detects the speed error ΔV between the target speed VC and the actual speed Vr, which will be described later. It generates and controls the speed.

4 is a position error detection circuit, which generates a position error signal ΔP from the position signal ps and the detection current c, and controls the position; 5 is a power amplifier and a switching section, which includes a changeover switch and It has a power amplifier and connects the speed error detection circuit 3b or the position error detection circuit 4 to the servo target 1 in response to a coarse (speed control #)/fine (position control) switching signal.

6 is the main control unit 69, which is composed of a microprocessor,
In addition to generating a target speed curve Vc according to the amount of movement, the position of the υ servo target 1 is monitored by track crossing pulses, which will be described later, and the transition from coarse to servo target 1 is performed near the target position.
This generates a switching signal to the input signal.

7 is a control current detection circuit that detects the control current Is of the power amplifier 5 and generates the detected current signal [c];
8 is a track crossing pulse generation circuit which generates a track crossing pulse from the position signal ps and outputs it to the main control section 6.0 The main control section 6 generates a track crossing pulse from the position signal ps and outputs it to the main control section 6. , generates a target speed curve Vc according to the number of moving tracks K, drives the voice coil motor 1a by speed control, and when it reaches near the target position, switches the switching unit 5 to the position control side K and moves the voice coil motor 1a to the position. control and position it on the desired track.

The servo circuit CT is constructed by the speed detection circuit 3a, speed error detection circuit 3b, position error detection circuit 4, power amplifier and switching section 5, main control section 6, control current detection circuit 7 and track crossing pulse generation circuit 81C. Configure.

In such a servo circuit, if there is an offset in the speed control section 3 or position control section 4, the seek time will be different in the reverse direction and the forward direction, and accurate fine control will not be possible, so adjustment is necessary. Also, if the speed gain is not appropriate, fine control cannot be achieved quickly, and variations in core width make the position signal Ps inaccurate and accurate speed cannot be obtained, so these adjustments are necessary.

In order to make such adjustments, conventionally, humans have to manually adjust the variable resistances of the speed control section 3, position control section 4, etc. by observing the servo circuit CTO position signal etc. with an oscilloscope while repeating the seek over a certain period. Ta.

[Problem to be solved by the invention]

However, in the conventional technology, Iruma observed and made adjustments using an oscilloscope, which caused problems such as adjustment variations due to individual differences and adjustment variations due to measuring instruments (oscilloscopes), etc., as well as the v4 adjustment cost and system. However, there was a problem in that it caused an increase in costs.

In order to solve this problem, the present applicant has proposed a technology for automatic adjustment of servo circuits in Japanese Patent Application No. 1-3183 entitled "Method for Automatic Adjustment of Speed Detection Gain of Servo Circuits", % Application No. 1-3184. Specification: ``Method for automatic adjustment of servo circuit of magnetic disk device'' l Specification of Japanese Patent Application No. 1-3185: ``Method of automatic adjustment of access time of servo circuit'' and Japanese Patent Application No. 1-3185
No. 3186, entitled "Position Control Offset Adjustment Method for Servo Circuit," has already been filed.

All of these proposed methods measure the operation of the servo circuit accompanying the seek operation and determine the adjustment value based on the measured value, but it is important to synchronize the seek operation with the index signal on the servo surface. If you do this without doing so, the following problems will occur.

Adjustment involves repeatedly giving adjustment values and performing seek operations to find the optimal adjustment value through trial and error. - Measured values vary widely due to disturbances in the track pattern on the board surface, making it difficult to measure for accurate adjustment.

In particular, when the track pitch is large, this is not so much of a problem, but as the track pitch becomes narrower, the influence of the servo pattern disturbance K becomes greater, and there have been situations where normal adjustment cannot be performed.

Therefore, an object of the present invention is to provide a method for adjusting a servo circuit for a magnetic disk device that allows accurate automatic adjustment.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1K, the present invention includes a servo head 1b for reading the servo surface of a magnetic disk 1c,
In a magnetic disk drive including a drive source 1a that drives a drive source 1a and a servo circuit CT that drives the drive source 1a in a seek manner based on the output of the servo head 1b, an adjustment value is given to the servo circuit CT and the drive source 1a is driven by the servo head 1b. In response to detecting the index signal from the output of 1b, the servo circuit CT
A seek drive is started, the operation of the servo circuit CT is measured based on the output of the servo head 1b due to the seek drive, and the adjustment value is determined based on the measurement result.

[Effect]

In the present invention, since the seek start is synchronized with the index signal on the servo surface, the operation can always be measured based on the output of the servo head 1b at the same position as the index.

Therefore, in each adjustment, even if the servo track lights on the servo surface vary, measurement can be made at the same position from the index, and the measurement for v4 adjustment can be accurate.

Follow me! ! Il adjustment can be performed accurately.

〔Example〕

(a) Description of the first embodiment FIG. 2 is a block diagram of the first embodiment of the present invention, and FIG. 3 is a block diagram of the position control section in the configuration shown in FIG.

In the figure, the same parts as those shown in FIGS. 1 and 14 are indicated by the same symbols.

9b is an integral section, and main control section (hereinafter referred to as MPU) 6
an absolute value circuit 91 that converts the position signal Ps from the switch 90 into an absolute value; an integrating circuit 92 that integrates the output of the absolute value circuit 91; An analog/digital converter (λD
C) 93.

10 is an index creation circuit, and servo node 1
An index signal is created from the output of b and is notified to the MPU 6.

60 is an offset register that stores the offset value Le; 61 is an integration number register that stores the number of integrations; 69 is a work register that stores various measured values FWD, RVS, TI, Ts. , Ts
, A are stored.

In FIG. 3, the position control unit 4 includes a filter 40 that cuts high frequency components of the position signal Pgo, an amplifier 41 that amplifies the output of the 7-ilter 40, an integration circuit 42 that integrates the output of the filter 40, and a filter 40 that cuts the high frequency component of the position signal Pgo. 40 output and control current detection signal Ic,! : a differentiating circuit 43 that differentiates, a position error generator 44 that generates a position error signal from the outputs of the amplifier 41, integrating circuit 42, and differentiating circuit 43, resistors r1 to r3, and resistor r ! connected to M
It has a digital/analog converter (referred to as DAC) that converts the digital offset value from the PU 6 into an analog offset amount and sets the offset of the differentiating circuit 43.

Since such a position control system is composed of analog circuits, circuit offset inevitably occurs.

In particular, the offset of the current feedback system is large, for example, the influence of the offset of the amplifier of the control current detection circuit 7 is large.

If there is no circuit offset, the position signal Ps will immediately converge to 0■ after switching from coarse (speed control) to fine (position control), and will not exceed a certain level (on-track level) for a certain period of time after switching to fine. This completes the seek.

However, if a circuit offset exists, after switching to fine mode, the position signal Ps gradually rises to correct the circuit offset, and the seek is completed without reaching a certain level for a certain period of time, but then a peak occurs and the position signal Ps is turned on. It may exceed the track level.

If this exceeds the on-track level, it means that the servo target 1 has been moved beyond the on-track level.

. . In order to automatically correct the circuit offset, especially the offset of the current feedback system, the adjustment value given to the position control unit 4 is changed, and the movement is repeated over a fixed distance, and each offset is adjusted. The integral value of the position signal during position control at the vI4JI value K is measured, and the offset adjustment value that minimizes the integral value is set as the optimum offset value.

That is, since the influence of the offset appears on the waveform of the position signal Ps in position control as described above, the position signal in position control is integrated while changing the offset value, and the offset value at which the integral value is the minimum is found. It is an attempt to adjust.

The offset can be adjusted automatically, eliminating the need for manual adjustment, making it possible to achieve error-free and cost-effective adjustment.

The operation will be explained in detail below.

FIG. 4 is a flowchart of adjustment processing according to the first embodiment of the present invention, and FIG.
The figure is a flowchart of the 7-odd/reverse offset adjustment value determination process of FIG. 4, FIG. 6 is a flowchart of the integral sampling process of FIG. 5, and FIG. 7 is an explanatory diagram of the operation.

5 is a subroutine of the flow shown in FIG. 4, and FIG. 6 is a subroutine of the flow shown in FIG.

First, the entire adjustment process will be explained with reference to FIG.

■ The MPU 6 resets various registers at the start of adjustment.

(2) Next, the MPU 6 executes a subroutine to be described later in FIG. 5, determines the forward direction offset adjustment value L, and stores the determined offset adjustment value L in the register 69 "FWD".

■ The MPU 6 further executes a subroutine described later in FIG. 5 to determine the offset adjustment value L in the reverse direction, and stores the determined offset adjustment value L in the register 69 @R.
V8”.

■ Next, the MPU6 sets the register 69's 'FWS'''
RVS'' is calculated and the average value is stored in the register 60 as “L”.
゛Set and output.

Next, the offset adjustment value determination process will be explained with reference to FIG.

■ First, the MPU 6 sets the integral number of the register 61 to "
3”. That is, the integration is performed three times.

@ MPU6 sets offset adjustment value L to register 60.
is set, and rLJ is output to the DAC 45 of the position control section 4.

Then, the MPU 6 executes an integral sampling subroutine, which will be described later in FIG.

At this time, this routine is repeated multiple times and the integral values are averaged.

Next, the MPU 6 updates L in the register 60 to (L+X) and updates the number of integrations in the register 61 to (A1).

(2) The MPU 6 checks whether the number of integrations I in the register 61 is "0", and if it is not "0", returns to step (2).

■ On the other hand, if ■ = 0, the three integral operations are completed and the integral value T. , T. , T. The current offset value is (L+3X).

First, the MPU 6 receives the first integral value T. and the second integral value T
．． Compare with.

T! ≧T. , that is, Tl
For +3X, reduce it to (L-X) and return to step ■.

■ On the other hand, T1≧T! If so, compare the second integral value T and the third integral value T3.

If T3≧T2, that is, Ts < T2, the minimum value cannot be obtained due to a monotonous decrease with respect to the increasing change in O7 set L. Therefore, set the offset L to (L-2X), that is, L=(
L+3X), so increase it to (L+X) and return to step ■.

■ Conversely, Ts≧T! Then, the relationship T1≧T:≦T holds true, and T2 becomes the minimum value, so T! The gain t-(
L-2X)=(L+X), stored in the register 69 as the forward direction offset determination value "F"WD", and returns.

Incidentally, the reverse direction offset determination value -RV8' is similarly obtained by performing integral sampling in the reverse direction at step @.

Next, the integral sampling process will be explained with reference to FIG.

(1) First, when this subroutine is called, the MPU 6 monitors the index signal of the index creation circuit 10, and when the index signal is detected, the scheduled
Start a 7-word seek of 1 length.

(H) The MPU 6 determines whether the speed control has ended, and when the speed control ends, issues an integration start signal, turns on the switch 90, and operates the integration circuit 92.

Therefore, as shown in FIG. 7, the integrating circuit 92 starts integrating the position signal Ps from the end of the speed control.

(in) In this way, after switching from speed control to position control, the on-track signal continues for a certain period of time.
Therefore, it is determined that the seek has ended.

After further waiting for a scheduled time, the integration start signal is turned off, the switch 90 is turned off, the integration circuit 92 is made inactive, and the integration is completed.

Therefore, the integration period becomes as shown in FIG.

Ov) After the integration period ends, the MPU 6 samples the integral value from the λDC 93 and stores it in the register 69 as rAJ.

Then, reverse seek by the planned amount and return.

The above flow is an integral sampling process in the forward direction, but in the reverse direction, 7 is processed in step (1).
Set backward seek to reverse seek, step Ov)
Just change reverse seek to forward seek with
The rest is the same.

In this way, there may be a difference in the offset between the forward direction and the reverse direction, so as shown in FIG. 4, offset adjustment values in both directions are determined and the average value is used as the automatic offset adjustment value.

Furthermore, since the offset value is determined such that the integral value of the position signal is the minimum, an appropriate offset adjustment value can be obtained.

In this way, while changing the offset, the integral value of the position signal Ps at each offset is measured, and the offset value with the minimum integral value is determined, so the circuit offset of the position control system can be automatically adjusted. play, v
4. No adjustment errors occur, adjustment costs can be reduced, and adjustments can be made easily in the field.

As shown in Figure 6, each integral assembly/kuni seeks in synchronization with the index, so
Since the position (or time) of each integral sampling is the same, it is possible to prevent the integral value of each time from being affected by disturbances in the track pattern on the servo surface, and to achieve accurate adjustment.0(b) Second implementation Explanation of an Example FIG. 8 is a configuration diagram of a second embodiment of the present invention, and FIG. 9 is a configuration diagram of a speed detection circuit in the configuration shown in FIG. 8. Items that are the same as those shown are shown with the same symbols. 09a is 6 in counter/ta.
! ). It is started/stopped by the main control section 6 and is used to measure the speed control continuation time tc.

62 and 63 are gain registers, and gain register 6
2 is a control current detection gain M, a gain register 63 is for storing a differential gain N, 64 is a flag register used for controlling the adjustment process, 6
Reference numeral 5 is an integration number counter register for storing the number of integrations, and 69 is a work register for storing various measured values Mf, Mr, Tie T, , T3, and others.

As shown in FIG. 9, the speed detection circuit 3a detects a detection current I
an amplifier 20 that amplifies the position signal Pc, a differentiation circuit 21 that differentiates the position signal Pc to generate a velocity component, an offset adjustment circuit 22, and an amplifier 23 that adds and amplifies the outputs of these.
t-, and furthermore, the detected current 1c from the amplifier 20 is multiplied by the control current detection gain M of the main control section 6, and the differential circuit 21C) multiplies the speed signal by the differential gain N of the main control section 6 and outputs them. Multiplier Digital/Analog Converter (DA)
C) has a value of 24.25.

In such a speed detection circuit 2, the overshoot/undershoot of the position signal Ps can be adjusted by adjusting the control current detection gain, and the coarse (speed control) time tc can be adjusted within a predetermined range by adjusting the differential gain. It can be adjusted to fit within.

For this automatic adjustment, the differential gain of the speed detection circuit 2 is changed, the movement is repeated over a certain distance, the speed control continuation time at each differential gain K is measured with a counter, and the measured speed control continuation is performed. The step of calculating the differential gain of the optimal speed control duration from the time, and the step of changing the control current detection gain of the speed detection circuit 2 and repeating movement over a certain distance, at least after the position control at each control current detection gain. A step of measuring the integral value of the position signal and a step of determining the control current detection gain of the minimum integral value of the measured integral values are provided.

In other words, since the access time (speed control duration) changes depending on the differential gain, change the differential gain, measure the speed control duration at each differential gain with a counter, and find the optimal differential gain for the speed control duration. .

Next, the waveform of the position signal ps before coarse/fine switching changes due to the speed control detection gain K, which affects the position error signal ΔP after fine control.

It is desirable that this position signal Ps converges to 0 immediately after the start of fine control. Therefore, the position signal Ps is integrated, the control error is determined, and the control current detection gain that minimizes the integral value is determined. Optimization of the waveform of the minimum position signal Ps is realized.

Next, its operation will be explained in detail.

FIG. 10 is a flowchart of the adjustment process according to the second embodiment of the present invention, FIG. 11 is a flowchart of the overshoot/undershoot adjustment process in FIG. 10, and FIG. 12 is a flowchart of the integral sampling process in FIG. FIG. 13 is an explanatory diagram of the operation.

12 shows the subroutine of FIG. 11, and FIG. 11 shows the subroutine of FIG. 10.

First, the flow shown in FIG. 10 will be explained.

■ At the start of the adjustment, the MPU 6 sets the adjusted flag F.
to "0" and initialize various registers.

At this time, initial values "M" and "N" are set in each of the gain registers 62 and 63, and the speed detection circuit 3a
Give a gain related to.

■ MPU 6 places voice coil motor 1 at the scheduled starting point.
Seek (move) a.

When the movement to the scheduled starting point is completed, the MPU 6 measures the access time, resets the counter 9a, and starts after the reset.

Then, the MPU 6 starts seeking a predetermined difference amount d from this starting point.

Therefore, the speed of the voice coil motor 1a is controlled by the speed error detection circuit 3b.

(2) The MPU 6u counts the track crossing pulses of the track crossing pulse generation circuit 8, and when it detects that it has reached the vicinity of the target position, it ends the speed control and switches to position control.

At the same time, the counter 9a is stocked.

As a result, the counter 9a measures the access time (speed control duration time) tc.
The MPU 8 outputs the position error detection circuit 40 on-track signal (
When the signal output when the position error signal ΔP is within a certain range continues for a certain period of time (800 μs), it is assumed that the position control has converged to the target position, and the seek is completed. , reads the measured value of the counter 9a, and checks whether the measured value of the counter 9a is within the expected range.

If it is within the planned range, proceed to step ■ to adjust the control current detection gain; if it is not within the planned target range, proceed to step ■ to adjust the differential gain.0■ If not within the planned target range, proceed to adjustment. In order to redo the adjustment, the adjusted flag F is reset to "O".

If the measured value of the counter 9a is faster than the target, the differential gain N of the register 63 is increased to (N+1); if it is not 9 earlier than the target, the differential gain N is decreased by (N-1)K, and the Output and return to step ■.

In other words, if it is faster than the target, the differential gain is increased and the actual speed is
If it is not faster than the target, the differential gain is made smaller to make the actual speed Vr appear smaller and the access time is made faster.

■ On the other hand, if the measured value of the counter 9b is within the scheduled range, the MPU 6 checks the adjusted flag F, and if F = "l'" indicates that the overshade/undershaft has been adjusted, the MPU 6 ends. do.

■ On the other hand, if F="1", that is, F="0", the overshoot/undershape adjustment has not been completed, so the overshoot/undershape adjustment described later in Figure 11 will occur. In the sinito adjustment subroutine, calculate the adjustment gain Mf t in the forward seek direction and register 6.
Store in 9.

■ Next, the MPU 6 calculates the adjustment gain y Mr in the reverse seek direction in the overshade/undershade adjustment subroutine described later in FIG.
Store in 9.

(2) Furthermore, the average of the forward seek adjustment gain Mf and the reverse seek adjustment gain Mr is calculated and stored in the register 62 as the control current detection gain M, and the process returns to step (2).

Next, the overshade/undershade adjustment process will be explained with reference to FIG.
Set the number of integrations I1c r3j in the register 65.

In other words, the integration is performed three times.0 @ The MPU 6 sends the DAC 24 of the speed detection circuit 3a,
Register 620 outputs control current detection gain M.

Then, the MPU 6 executes an integral sampling subroutine to be described later in FIG. 12, obtains the integral value of the position signal Ps from the register, and stores it in the register T1.

At this time, this routine is repeated multiple times and the integral values are averaged.

Next, the MPU 6 sets the gain M of the register 62 to (M+X
) K is updated, and the number of integrations d in the register 65 is updated to (I-1).

(2) The MPU 6 checks whether the number of integrals in the register 65 is "o", and if it is "0", returns to step (2).

■ On the other hand, if I:0, the three integral operations have been completed and the integral value T1, T,, T, has been changed, and the current gain is (M+3X).

First, the MPU 6 compares the first integral value TI and the second integral value T2.

T1≧T, ie. TI<T! If so, the minimum value cannot be obtained because the gain M monotonically increases with increasing change, so the gain M can be set as (M-4X), that is, M:M+
Reduce to (M-X) for 3X and return to step ■K.

(2) On the other hand, if TI≧T2, the second integral value T and the third integral value T are compared.

T$≧T! If not, that is, Ts < Tt, then the gain M
Since the minimum value cannot be obtained because of the monotonous decrease with respect to the increasing change of , the gain M is increased by (M-2X), that is, (M+X)κ, and the process returns to step (2).

■ Conversely, T3≧T! Then, T! Since the relationship ≧T2≦T3 holds and Tz becomes the minimum value, the gain of T2 is set as (M
−2X)=(M+X), and store it in the register 69 as the forward direction control current detection gain Mf.
Set the adjusted flag F to "1" and return.

Incidentally, the control current detection gain Mr in the reverse direction is similarly obtained by performing integral sampling in the reverse direction in step (3).

Next, the integral sampling process will be explained with reference to FIG.

(1) When this subroutine is called, MPU 6. The index signal of the index creation circuit 10 is monitored.

When the MPU 6 detects the index signal, it starts a forward seek of a predetermined difference amount.

(li) The MPU 6 determines whether it is half a track before the target position, and when it is half a track before, issues an integration start signal, turns on the switch 90, and operates the integration circuit 92.

Therefore, the integrating circuit 92 starts integrating the position signal Ps from half a track before, as shown in FIG.

(III) Thereafter, speed control is switched to position control, and as in step (2) in FIG. 10, when the on-track signal continues for a certain period of time, it is determined that the seek has ended.

After further waiting for a scheduled time, the integration start signal is turned off, the switch 90 is turned off, the integration circuit 92 is made inactive, and the integration is completed.

Therefore, the integration period becomes as shown in FIG.

After the integration period ends, the QvlMPU 6 samples the integral value from the ADC 93 and stores it in the register 69 as "person".

Then, reverse seek by the planned amount and return.

The above flow is an integral sampling process in the forward direction, but in the reverse direction, 7 is processed in step (1).
Forward seek is changed to reverse seek, step (IV
), the rest is the same except that reverse seek is changed to forward seek. In this way, in Fig. 10, find the differential gain N for an appropriate access time, and then find the differential gain N for an appropriate positioning waveform. Find the control current detection gain M.

Since the access time occupies most of the positioning time, first adjust the differential gain to optimize the access time, and then find the control current detection gain N that minimizes overshoot/undershoot in that differential gain. In order to check whether the access time does not deviate from the predetermined range by changing the detection gain N, the differential gain is adjusted again.

If the access time is outside the predetermined range, the differential gain is adjusted again.

Also, the reason why the integration for adjusting the control current detection gain is performed half a track ago is because the control current detection gain affects coarse control (speed control), and the zero of the position signal ps at the time of coarse/fine switching. This is because the angle of entry into the bolt affects the undershitch and overshitch K of the subsequent position control.

For this reason, the period from half a track before, that is, the coarse period immediately before the coarse/fine switching is also included in the integration.

In the above embodiment, the integration is performed from half a track ago, but if you integrate the position signal in position control, you can understand the effect of the gain on the entry angle mentioned above, so it is necessary to integrate the position signal from the start of position control. In this way, by adjusting the differential gain, which is the speed detection gain, from the speed control duration and the control current detection gain from the integral value of the position signal, the speed detection gain can be automatically adjusted. This has the effect of being able to be adjusted to the desired level, without causing adjustment errors, reducing adjustment costs, and allowing automatic adjustment in the field.

In this example as well, since the seek is performed in synchronization with the index in each integral sampling, each integral sampling position is the same, and it is possible to prevent the integral value of each time from being affected by the disturbance of the track butter on the servo surface. , Accurate adjustment is possible〇(C) Description of other embodiments In the above embodiment, the seek operation is performed in synchronization with the index in order to keep the integral sampling position constant.
For example, the seek start in the rounding step (2) of measuring the coarse period in FIG. 10 may be synchronized with the index, and in this case, the seek operation can be stabilized and the coarse time can be measured accurately.

Also, 4? The present invention may be applied to the seek operation for adjusting the core width of Japanese Patent Application No. 1-3184 and the seek operation for equalizing the seek time in the forward/reverse direction as described in Japanese Patent Application No. 1-3185.

Although the present invention has been described above with reference to embodiments, the present invention can be modified in various ways according to the spirit of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the developed IMIc, the measured value is measured by performing a seek synchronized with the index.
This has the effect of being able to always obtain measured values at the same position, increasing the measurement accuracy for adjustments that are performed multiple times through trial and error, and allowing accurate adjustments to be made.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a block diagram of the first embodiment of the present invention, Fig. 3 is a block diagram of the position control section in the configuration shown in Fig. 2, and Fig. 4 is a diagram of the first embodiment of the present invention. FIG. 5 is a flow diagram of the offset adjustment value determination process in FIG. 4, FIG. 7 is an explanatory diagram of the operation of the first embodiment of the present invention, and FIG. FIG. 9 is a configuration diagram of the speed detection circuit in the configuration shown in FIG. 8, FIG. Overshoot/undershoot adjustment processing flow diagram, FIG. 12 is an integral sampling processing flow diagram in FIG. 11, FIG. 13 is an operation I112BA diagram of the second embodiment of the present invention,
FIG. 14 is an explanatory diagram of the prior art. In the figure, 1a... Drive source (voice coil motor), 1b
...Servo head, 1c...Magnetic disk, CT...Servo circuit.

Claims (1)

[Claims] A servo head (1b) that reads a servo surface of a magnetic disk (1c), a drive source (1a) that drives the servo head (1b), and a drive source (1a) that drives the servo head (1a). In a magnetic disk drive including a servo circuit (CT) that performs seek drive based on the output of the servo head (1b), an adjustment value is given to the servo circuit (CT), and an index signal is detected from the output of the servo head (1b). In response to this, seek drive of the servo circuit (CT) is started, the operation of the servo circuit (CT) based on the output of the servo head (1b) due to the seek drive is measured, and based on the measurement result, A method for adjusting a servo circuit for a magnetic disk device, the method comprising determining the adjustment value.