JPH05342779A - Positioning control method in magnetic disk device - Google Patents

Abstract

PURPOSE:To always maintain a normal gain by providing a correcting operation in which values of correction coefficients are learned in respective zones and correction is made by multiplying a positional error signal with a value of a correction coefficient corresponding to a zone in which a head currently exists during a tracking operation. CONSTITUTION:In response to a drive instruction sent from a CPU 9 to a VCM driver 16 at every predetermined intervals after activation, seek is made to locate a head 2 on a track of the outermost zone of a disk 1. Then, the operation mode is switched to a tracking mode, and a correction coefficient is determined by a predetermined calculation based on A and B burst integration values EA and EB received from the CPU 9 through an A/D converter 8. A value of the correction coefficient is determined for every zone and stored in registers 13. The value of the correction coefficient corresponding to the zone is read from the registers 13 during the seek mode, and a positional error signal EA-EB is multiplied by the correction coefficient after completion of the seek. In this manner, the correcting operation is performed so that the gain of the positional error signal can always be kept the same in every zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic disk for positioning a recording / reproducing head on an arbitrary track in a magnetic disk in which servo information used for positioning the recording / reproducing head is written on a recording medium. The present invention relates to a positioning control method for a disk device.

[0002]

2. Description of the Related Art In a magnetic disk device, the magnetic head is moved and positioned by a driving means such as a voice coil motor with respect to a predetermined track of one or a plurality of magnetic disks rotating at a constant speed. Data is read or written.

The positioning control method of the magnetic head in the magnetic disk device is classified into a servo surface servo system and a sector servo system. The former servo surface servo method records servo information on another surface different from the data recording surface, and the latter sector servo method intermittently holds servo information on the data recording surface. Servo information is recorded only on one or a plurality of servo selectors among the selectors, and data is recorded on the other data selectors.

In the servo surface servo system, since the magnetic disk on which servo information is recorded is different from the magnetic disk on which data is recorded, there is a problem of misalignment due to temperature change and the like as the recording density is increased. On the other hand, in the sector servo system, the sector in which the data is written and the sector in which the servo information is recorded are formed on the same magnetic disk surface, so that the influence of the positional deviation due to the temperature change or the like is small. Therefore, when the number of magnetic disks is reduced in order to realize both high-density recording and downsizing, the sector servo system is often used.

The amplitude of the read signal of the magnetic head varies depending on the flying height of the magnetic head, the relative speed with respect to the magnetic disk, etc. In order to make this amplitude constant, the AGC is used.
A configuration in which a read signal of a magnetic head is amplified by an amplifier is generally known.

One of the methods for increasing the data storage capacity per disk is ZBR (zone bitr).
An encoding method has been devised (for example, Japanese Patent Laid-Open No. 59-901). This is a recording method in which the disk is divided into several zones and the data recording frequency is changed for each zone. Conventionally, since the disk rotation speed and the data recording frequency were constant, the recording density at the innermost circumference was the highest and the recording density at the outermost circumference was the lowest.
The recording density on the outer peripheral side can be increased by the R method, and the recording density of the entire disk is averaged, so that the storage capacity per disk is improved. In this method, since the data recording frequency is changed for each zone, the band of the low pass filter for noise removal must be changed in conjunction with it.

FIG. 3 is a block diagram showing the structure of a reproducing circuit of a conventional magnetic disk device. In FIG. 3, 2
Is a head, 4 is a head amplifier, 5 is a filter, 6 is an AG
C amplifier, 7 is an integrator.

FIG. 4 is a diagram showing how zones are divided on the disk surface. A conventional positioning control method for the magnetic disk device configured as described above will be described.

The data area on the disk is divided into n zones as shown in FIG. For the above reason, the data recording frequency is changed in each zone in order to increase the recording density. The data recording frequency is highest in the zone Z _{1, the} data recording frequency becomes lower toward the inner circumference, and the data recording frequency becomes the lowest in the zone Zn. The filter 5 is a low-pass filter for removing high-frequency noise, and can be switched to a filter having a band most suitable for the data writing frequency in association with a change in zone.

The data written on the disk is read by the head 2 and the reproduced signal is read by the head amplifier 4.
Is amplified by. The amplified reproduction signal is filtered by the filter 5.
In, the filter of the band corresponding to the zone where the head 2 is currently located is selected, and the high frequency noise of the reproduced signal is removed. The reproduced signal passed through the filter 5 is the AGC amplifier 6
The signal is amplified to a prescribed amplitude in step S3, and only the A and B burst portions in the servo sector area of the reproduced signal are sent to the integrator 7. FIG. 5a is a pattern of the A and B burst portions of the servo sector, FIG. 5b is a reproduction signal when the head 2 is on-track,
FIG. 5c shows the absolute value of the reproduced signal.
In the integrator 7, as shown in FIGS.
The absolute values of the reproduced signals in the burst section are integrated, and the integration result is output. Integration result and E _A of the A burst, the integration result E _B of the B burst is subtracted (E _A -E _B), the position error signal to know the position of the head 2 on the disk is formed. If the head 2 is on-track, the integration result E _A of the _A burst and the integration result E _B of the B burst become equal.
Position control system E _A -E head 2 so that the value becomes 0 the _B
To control.

[0011]

However, in the conventional configuration, a low-pass filter with a low band is used because the data recording frequency is low on the inner side, and a low-pass filter with a high band is used on the outer side because the data recording frequency is high. Since it is used, the reproduced waveform having the high frequency components removed as shown in FIG. 6a is used on the inner peripheral side, and the reproduced waveform containing the high frequency components shown in FIG. 6b is used on the outer peripheral side. The amplitudes of the waveforms in FIGS. 6a and 6b are equal due to the effect of AGC, but since the integration result of the integrator is affected by the shape of the reproduced waveform, the waveforms of FIGS.
The amplitude of b is smaller. Therefore, the gain of the position error signal obtained by the difference E _A −E _B between the integration result E _{A of the A} burst and the integration result E _B of the B burst fluctuates in the inner and outer circumferences, and there is a drawback that the characteristics of the position control system vary. ..

[0012] The present invention has been made to solve such conventional problems, be varied gain of the position error signal zone the head on the disk is located is changed is calculated by E _A -E _B An object of the present invention is to provide a method for always correcting the gain to a normal value and keeping the characteristics of the position control system in the inner and outer circumferences in a constant state.

[0013]

In order to solve the above problems, a positioning control method for a magnetic disk drive according to the present invention moves a recording / reproducing head to concentrically divided areas on a disk-shaped recording medium. Step, and a first burst pattern, which is periodically recorded on the disk-shaped recording medium, is displaced by a half track pitch from a data recording track, and a second burst pattern is displaced by a half track pitch in the radial direction. Detecting a servo signal having a burst pattern, and obtaining a correction coefficient based on the reciprocal of the addition result of the integrated value of the detection signal of the first burst pattern and the integrated value of the detection signal of the second burst pattern. And a position error signal representing the relative position of the recording / reproducing head and the recording medium based on the step and the integrated value of these detection signals. A step that is one having a structure having a step of multiplying said correction factor to said position error signal.

[0014]

Therefore, the present invention has the following operations by the above method. That is, the value of the correction coefficient is learned in each zone, and the value of the correction coefficient corresponding to the zone where the head is currently positioned is multiplied by the position error signal during tracking so that the gain of the position error signal is the same in all zones. By correcting, even if the zone where the head is positioned on the disk changes and the gain of the position error signal changes, it can always be corrected to a normal gain, and the position control system can be maintained in a stable state. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a magnetic disk drive positioning control apparatus for realizing a magnetic disk drive positioning control method according to an embodiment of the present invention. In FIG. 1, 1 is a filter, 2 is a head, 3 is a VCM actuator, 4 is a head amplifier, 5 is a filter, 6 is an AGC amplifier, 7 is an integrator, 8 is an A / D converter, and 9 is CP.
U, 10 is a position error signal decoding unit, 11 is a position control system gain adjusting unit, 12 is a correction coefficient multiplying unit, 13 is a register, 14 is a D / A converter, 15 is a phase compensator, 16
Is a VCM driver.

An outline of the operation of the positioning control device of the magnetic disk device having the above configuration will be described below with reference to the drawings.

In FIG. 1, the data on the disk 1 is read through the head 2, then amplified by the head amplifier 4 and sent to the filter 5. A plurality of filters 5 are prepared for each band, of which the head 2 is the disk 1
A filter having a band corresponding to the data recording frequency in the upper zone is selected. The reproduction signal from which the high frequency noise has been removed by the filter 5 is amplified by the AGC amplifier 6 to a prescribed amplitude. Of the amplified reproduced signal, only the A burst portion and the B burst portion of the servo sector area are sent to the integrator 7, and the absolute values of the reproduced signals of the A burst portion and the B burst portion are integrated and output. ..
A burst integral value E _A and B burst integral value E _B are A /
After being converted into a digital value by the D converter 8, it is taken into the CPU 9. The taken-in data is subjected to the operation E _A -E _{B in} the position error signal decoding unit 10 to form a position error signal. The position error signal is multiplied by a constant K for adjusting the position control system gain in the position control system gain adjusting unit 11. In the correction coefficient multiplication unit 12, the corrected position error signal obtained by multiplying the position error signal by the correction coefficient Kc read from the register 13 is converted into an analog value by the D / A converter 14, and the phase compensator 15 Sent to. In the phase compensator 15, the signal output after the loop stabilization processing of the position control system is performed becomes a drive command and becomes V
It is sent to the CM driver 16 to operate the VCM actuator 3 to position the head 2 at the target position.

The detailed operation of the positioning control device of the magnetic disk device that performs the above operation will be described below with reference to the drawings.

FIG. 2 is a flowchart of the positioning control method. Referring to FIGS. 1 to 5, when the magnetic disk device is started, or at every fixed time after the start, the CP
A drive command is sent from the U9 to the VCM driver 16 to move the head 2 to a predetermined track (for example, the zone Z ₁ ) having the zone Z ₁ (FIG. 4) which is the outermost zone on the disk 1.
Seek to the center track of (S1). When the seek ends, the mode switches to tracking mode (S2), CP
The value of the correction coefficient Kc = 1 / E _A E _B is obtained from the A burst integrated value E _A and the B burst integrated value E _B (FIG. 5) taken in by the U9 through the A / D converter 8 (S3). The value of the obtained correction coefficient Kc is recorded in the register R ₁ inside the CPU 9 (S4). After that, the zone value i = 1 is compared with the value of n which is the total number of zones on the disk 1 (S5), and i
If not n, the value of i = 1 is incremented (S
6) and steps (S1) to (S5) are repeated. i
= N, that is, when the learning of the correction coefficient Kc is completed in all zones, the initial setting at startup is completed.

At the time of seeking, the value of the correction coefficient Kc corresponding to the zone Zj in which the target track x is included is stored in the register Rj.
It is taken out from 13 and held as Kcj (Sa).
When the seek is executed and the head 2 is moved to the target track (Sb) and the seek is completed, the mode is switched from seek to tracking (Sc), and the position error signal E _A −
Multiplied by the value of the correction coefficient Kcj taken out in the step from the register Rj13 to E _B, it corrects the position error signal gain. As shown in FIG. 5A, the A and B bursts are alternately arranged while being deviated by half tracks from the on-track position. Therefore, the sum of the integrated value of the A burst read by the head 2 and the integrated value of the B burst is the reproduced waveform. The same value is obtained regardless of the position of the head 2 on the disk unless the shape of the head changes. Therefore, by comparing the sum of the integrated value of the A burst and the integrated value of the B burst at a certain position with the sum of the integrated value of the A burst and the integrated value of the B burst at another position, the shape change rate of the reproduced waveform can be calculated. You can get soup powder. Therefore, by multiplying the position error signal E _A −E _B by 1 / E _A + E _B , the position error signal can be normalized.

[0022]

As is apparent from the above description, according to the present invention, the zone in which the head is located on the disk is changed and E _A is changed.
Even if the gain of the position error signal obtained by −E _B varies, the position error signal is always normalized by multiplying the value of the correction coefficient 1 / E _A + E _B to normalize the position error signal. It can be corrected and the position control system can be kept in a stable state.

[Brief description of drawings]

FIG. 1 is a block diagram of a positioning control device for a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a positioning control method for a magnetic disk device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a reproducing circuit of a conventional magnetic disk device.

[Figure 4] Zone layout on the disc

FIG. 5 is a servo pattern diagram and a waveform diagram showing an integration method of A and B bursts.

FIG. 6 is a waveform diagram showing reproduced signals of servo patterns on the inner and outer circumference sides of the disk.

[Explanation of symbols]

 1 disk 2 head 3 VCM actuator 4 head amplifier 5 filter 6 AGC amplifier 7 integrator 8 A / D converter 9 CPU 10 position signal decoding unit 11 position control system gain adjusting unit 12 correction coefficient multiplying unit 13 register 14 D / A converter 15 Phase compensator 16 VCM driver

Claims (1)

[Claims] 1. A step of moving a recording / reproducing head to each of concentrically divided areas on a disc-shaped recording medium, and recording on the disc-shaped recording medium periodically.
A step of detecting a servo signal composed of a first burst pattern arranged at a half track pitch offset from a data recording track and a second burst pattern arranged at a half track pitch offset in the radial direction; A step of obtaining a correction coefficient based on the reciprocal of the addition result of the integrated value of the detection signal of the burst pattern and the integrated value of the detection signal of the second burst pattern; and the recording / reproducing head based on the integrated value of these detection signals. And a step of generating a position error signal representing a relative position of the recording medium, and a step of multiplying the position error signal by the correction coefficient.