JPH04170775A - Magnetic disk device and controlling method therefor - Google Patents

Abstract

PURPOSE:To enable tracing property of a head for a recording cylinder to be improved by using a sinusoidal wave signal of a plurality of frequency components of position servo information and then compensating for position servo information at the time of recording/reproduction. CONSTITUTION:A sinusoidal wave signal whose frequency is two times larger than a rotary frequency f of a disk is extracted out of frequency components of position deviation detection signal (reproduction signal of a position information pattern SS) between a recording cylinder CL and heads 5 and 6 of a disk 1, a signal indicating a relative motion trace of the heads 5 and 6 for the cylinder CL is created by using an addition signal, a reproduction signal of a pattern SS which is obtained at the time of recording/reproduction is compensated for, and then the heads 5 and 6 are accurately traced to the cylinder CL. A cycle function f (x) with a period of 2pi is expanded into Fourier series (IV - VI), thus indicating a discrete value where f(x)cos(x) is divided into m equal sections (0, m). A Fourier series indicating a signal of a frequency component with a frequency of 2f are shown similarly. A subscript k is a sector SC number which has detected position deviation. This configuration allows a signal indicating relative motion between CL and the head to be formed highly accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention records a plurality of position servo information at predetermined angular intervals on a recording cylinder of each recording surface, and performs Fourier transform on the reproduction signal of the position servo information. Then, the fundamental frequency component of the reproduced signal is extracted, and the sine wave signal of the extracted fundamental frequency component is stored in advance, and when recording/reproducing data, based on the composite signal of the reproduced signal of the position servo information and the sine wave signal, The present invention relates to a magnetic disk device capable of replacing a recording medium for adjusting the position of a magnetic head that records/reproduces data on a magnetic disk in the radial direction of the magnetic disk, and a control method thereof.

[Prior Art] Generally, in a magnetic disk device in which the recording medium is replaceable,
When the recording medium is loaded, the center of the recording medium deviates from the center of the rotation axis of the spindle motor that rotates the recording medium.

In this way, the recording medium is mounted eccentrically from the rotation axis of the spindle motor, so when the magnetic head is fixed, the positional relationship between the center of the magnetic head and the center of the recording track formed on the recording medium may change. However, this changes periodically as the recording medium rotates, making it impossible to appropriately record/reproduce data on the recording track.

Therefore, position servo information that can detect the deviation from the center position is recorded on the recording track (recording cylinder) formed on the recording medium, and the reproduction signal of this position servo information is used when recording/reproducing data. By moving the magnetic head in the radial direction of the recording medium, the influence of eccentricity of the recording medium is removed.

However, for example, when the rotation speed of the recording medium is increased to shorten data access time,
The response side of the position servo control of the magnetic head performed using this position servo information becomes poor, resulting in the inconvenience that the influence of eccentricity of the recording medium cannot be sufficiently removed.

As a technique for solving such inconveniences, there is a technique disclosed in US Pat. No. 4,628,379, for example.

In this conventional technology, prior to data recording/reproducing operation,
The playback signal of the position servo information is Fourier transformed, the fundamental frequency component of the playback signal is extracted and saved, and data recording/
During reproduction, the position of the magnetic head in the radial direction of the magnetic disk is adjusted by correcting the reproduction signal of the position servo information with the extracted fundamental frequency component signal.

This makes it possible to eliminate misalignment between the magnetic head and the recording cylinder due to eccentricity, even for recording media that rotate at high speeds that cannot be tracked by magnetic head position servo control, allowing the magnetic head to record/reproduce data. can be carried out appropriately.

[Problems to be Solved by the Invention] However, such conventional techniques have the following disadvantages.

In other words, the causes of misalignment between the recording cylinder and the magnetic head include, in addition to eccentricity of the recording medium, for example: Distortion of the recording medium due to anisotropy in the expansion characteristics of the recording medium; Since the positional misalignment between the cylinder and the magnetic head cannot be eliminated, there has been a problem in that it cannot be sufficiently corrected, especially when the density of the recording cylinder becomes large.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic disk device and a control method thereof that can eliminate the disadvantages of the prior art and allow a magnetic head to appropriately follow a recording cylinder.

[Means for Solving the Problem] The present invention transforms a reproduced signal of position servo information into a fundamental frequency component of the reproduced signal and a sine wave signal of a predetermined times the fundamental frequency component by Fourier-transforming the reproduced signal of position servo information prior to data recording/reproducing operation. and a position for adjusting the position of the magnetic head in the radial direction of the magnetic disk based on a reproduction signal of position servo information during data recording/reproduction and a composite signal of a plurality of sine wave signals. A position adjustment signal calculation means for calculating an adjustment signal; and a control means for adjusting the position of the magnetic head in the radial direction of the magnetic disk in synchronization with the rotation of the magnetic disk using the position adjustment signal calculated by the position adjustment signal calculation means. It is prepared.

In addition, prior to data recording/reproducing operations, the reproduced signal of the position servo information for each recording surface is Fourier-transformed to extract the fundamental frequency component of the reproduced signal and a sine wave signal of a frequency component that is a predetermined multiple of the fundamental frequency component. a signal extracting means for storing the position servo information during data recording/reproduction, and a position adjustment signal for adjusting the position of the magnetic head in the radial direction of the magnetic disk based on the reproduction signal of the position servo information and the plurality of sine wave signals. The magnetic disk radius of the magnetic head is adjusted in synchronization with the rotation of the magnetic disk using a position adjustment signal calculation means that calculates for each surface and a position adjustment signal calculated by the position adjustment signal calculation means corresponding to the recording surface accessed by the magnetic head. It is equipped with a control means for adjusting the position in the direction.

In addition, prior to data recording/reproducing operations, the reproduced signal of the position servo information for each recording surface is Fourier-transformed to extract the fundamental frequency component of the reproduced signal and a sine wave signal of a frequency component that is a predetermined multiple of the fundamental frequency component. and calculates a position adjustment signal for each recording surface to adjust the position of the magnetic head in the radial direction of the magnetic disk based on the playback signal of position servo information and multiple sine wave signals during data recording/playback. However, the position of the magnetic head in the radial direction of the magnetic disk is adjusted in synchronization with the rotation of the magnetic disk using a position adjustment signal in accordance with the recording surface accessed by the magnetic head.

[Effects] Therefore, since the position servo information is corrected during data recording/reproduction using a sine wave signal of multiple frequency components of the position servo information, it is possible to improve the tracking side of the magnetic head with respect to the recording cylinder. data can be recorded/reproduced appropriately.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a magnetic disk according to an embodiment of the present invention.

This magnetic disk 1 has a large number of concentric recording cylinders CL formed at predetermined intervals, and each recording cylinder CL has a fixed data length occupying a predetermined central angle, as shown in FIG. A sector SC is formed.

A position information pattern SS for detecting a deviation from the center position of the recording cylinder CL is formed at the beginning of each of these sectors SC.

When this positional information pattern SS is reproduced, as shown in FIG. , the reproduced value takes the value of the reference value VT, and the magnitude of the reproduced value changes depending on the positional deviation in the radial direction (tracking direction) between the recording cylinder CL and the magnetic disk l of the magnetic head.

FIG. 4 shows a schematic configuration of a medium exchange type magnetic disk device according to an embodiment of the present invention.

In the figure, a turntable 4 for fixing a magnetic disk 1 is disposed at the tip of a rotating shaft 3 of a spindle motor 2, and a turntable 4 for fixing a magnetic disk 1 is arranged to record data on recording surfaces formed on both sides of the magnetic disk 1. The magnetic heads 5 and 6 for recording/reproducing are mounted on a common carriage 7,
The seek motor 8 moves the magnetic disk l in the radial direction.

Further, the magnetic disk 1 is attached to and detached from the turntable 4 by a loading mechanism (not shown).

FIG. 5 shows an example of a control system of the magnetic disk device shown in FIG.

In the figure, a control unit 10 controls the operation of each part of this magnetic disk device, and also includes a host device (shown in the diagram) such as a personal computer that uses a magnetic disk.
The host interface circuit 11 is for exchanging various information between the control unit 1o and the host device, and the data recording/reproducing circuit 12 is for exchanging predetermined data with the magnetic head 5. The selector 13 is for connecting either one of the magnetic heads 5 or 6 to the data recording/reproducing circuit 12.

The position information detection circuit 14 extracts a reproduction signal of the position information pattern SS from the reproduction signals from the magnetic heads 5 and 6 output from the selector 13, and the detection signal SK is applied to the control section 10. ing.

The position sensor 15 is for detecting the position of the carriage 7 in the magnetic disk radial direction, and sends a detection signal S.
P is added to the control section 10.

The spindle motor drive section 16 drives the spindle motor 2, and the speed sensor 17 detects the rotational speed of the spindle motor 2, and its detection signal PS is applied to the control section 10.

The display unit 18 is for displaying the operating status of the magnetic disk device, and its operation is controlled by the control unit 10.

The waveform memory 19 stores a cosine waveform signal with a period f corresponding to the rotational speed of the magnetic disk 1, a sine wave signal with a period f, and a cosine waveform signal with a period 2f corresponding to twice the rotational speed of the magnetic disk 1. , and waveform data obtained by sampling a sine wave signal with a period of 2f in accordance with the timing at which the positional information pattern SS is formed in accordance with the rotation of the magnetic disk I is stored. An example of a cosine waveform signal with period f is shown in FIG. 6(a).

Now, in this embodiment, the recording cylinder C of the magnetic disk 1 is
Among the frequency components of the detection signal of the positional deviation error between L and the magnetic head 5.6 (that is, the reproduction signal of the position information pattern SS), the frequency f corresponding to the rotation period of the magnetic disk 1
A sine wave signal with a frequency component of 1 and a sine wave signal with a frequency component of 2f, which is twice the 1 frequency f, are extracted, and a signal obtained by combining (adding) these sine wave signals is used to control the magnetic head for the recording cylinder CL. 5.6, and by correcting the reproduction signal of the position information pattern SS obtained during data recording/reproduction, the magnetic heads 5 and 6 are attached to the recording cylinder CL. I try to make it follow accurately. (The following is a blank space) The period number "(X) with a period of 2π can be expanded into a Fourier series as shown in the following equation (1).

f(x)=a,/2+Σ(a,C05(nx)+b,5
IN(nx))-(1)dHere, aTllbn is a Fourier coefficient and is expressed as follows.

a,,・l/yt f f(x)CO5(nx)dx
=(II)b,,=l#r f f(x)SIN
(nx)dx (III) Also, the period 2π component of the function f(x) can be expressed as follows.

f(x): atCO5(x)+b, 5IN(x) −
(IV)a,・1. #c f f(x)CO5(nx
)dx −(V)bl=l/πff(x)SIN(n
X) dX...(V■) Here, f (x) CO5(x
) is expressed as discrete values divided into m equal parts in the interval (0, m), then the Fourier series a, , b are expressed as follows.

a,=(2/m)Σf(x,)CO5(x,)...
(VTI)k(+b,=(27m)Σf(x,)SIN(x,) =(
VIII)k→ Similarly, the Fourier series f(x)' and the Fourier coefficient, 1°b,
' is expressed as follows.

f(x)'=at'C05(2x)+b,'5IN(2
x) -BeIX)a,' = (2/m)Σf(xJc
Os(2xb) −(X)bt”(2/m)Σf(x
k) SIN(2x-)...(XI) Also, in these formulas, the suffix is the sector number of the sector SC in which the positional deviation error signal was detected.

In this way, a positional deviation error signal is calculated for each sector SC, and using these positional deviation error signals, a sine wave signal (Fourier series) of the frequency component of frequency f and a sine wave signal of frequency 2f are generated. By calculating the sine wave signals and synthesizing the sine wave signals, it is possible to accurately form a signal that indicates the relative movement between the recording cylinder CL and the magnetic heads 5 and 6. (Margin below) Now, in this embodiment, the process shown in FIG. 7 is executed to detect the position correction data of the recording cylinder CL and the magnetic heads 5 and 6 when the magnetic disk 1 is rotationally driven. ing. This process is executed as part of the initial setting process performed in preparation for starting to drive the magnetic disk 1.

First, when it is detected that the magnetic disk l is attached to the magnetic disk drive device, the spindle motor 2 is driven to rotate, and when the rotation speed reaches a predetermined value (process 101)
, drives the sheave motor 8 and moves the magnetic heads 5 and 6 to position information pattern SS in the effective recording area of the magnetic disk 1.
to the detection reference position (process 102).

Next, by selecting one of the magnetic heads 5 and 6 using the selector 13, one recording surface of the magnetic disk 1 is selected (processed 103), and from the position information detection circuit 14, starting from the rotation reference position of the magnetic disk l. Each sector S to be output
Detection signal S of position information pattern SS arranged in C
Input K and save it as a position signal PES (Fig. 6 (
b) Reference; Process 104).

Next, for the recording surface, the Fourier coefficients at and bt in each sector SC are calculated based on the above-mentioned formula (v1■) and formula (VIrI).
106), and from those calculation results, the above-mentioned formula (V I
), the Fourier series F (x) in each sector SC is calculated (process 1o7). The Fourier series F (x) obtained here corresponds to the value of the sine wave signal of frequency f in the sector SC.

Next, for the recording surface, the Fourier coefficients a, +, bl' in each sector SC are calculated based on the above-mentioned formula (X) and formula (xB).
, 109), and from the calculation results, the above formula (IX
), the Fourier series F(x)' in each sector SC is calculated (processing 110). The Fourier series F (x) ' obtained here corresponds to the value of the sine wave signal of frequency 2f in the sector SC.

Then, for each sector SC, the Fourier series F (x) and the Fourier series F (x)' are added, and correction data DF is calculated and saved (process 111).
.

When the calculation of the correction data DF for one recording surface is completed, it is determined whether the calculation of the correction data DF for all recording surfaces has been completed (determination 112), and when the result of determination 112 is No, Returning to step 103, correction data DF is calculated for another recording surface.

When the calculation of the correction data DF for all recording surfaces is completed and the result of judgment 112 becomes YES, the process moves to the next step of the initial setting process.

In this way, when the magnetic disk l is loaded, correction data DF is calculated and saved for each recording surface of the magnetic disk l.

Now, when data recording/reproduction is commanded from the host device with the sector address of the target sector specified, the control section 10 performs a seek process as shown in FIG. to the target sector.

That is, based on the sector address specified at that time, the recording surface of the magnetic disk l and the recording cylinder CL are
201, 202), and the selector 13 selects the magnetic heads 5, 6 corresponding to the determined recording surface.

At the same time, the correction data DF corresponding to the determined recording surface is selected (process 203), and the position correction operation of the magnetic heads 5 and 6 is started (process 204). Move 6 (process 2
05).

Then, when the movement of the magnetic heads 5 and 6 is completed, it is checked whether the data recording/reproducing circuit 12 has detected the target sector (determination 206), and when the result of determination 206 is YES, the host device (process 207).

Further, when the result of the judgment 206 is No, a seek correction amount corresponding to the distance and direction between the positioned recording cylinder CL and the target cylinder is calculated (step 208), and the magnetic heads 5 and 6 are adjusted according to the seek correction amount. The correction movement process 209) returns to the judgment 206.

In this way, when the sector specified by the host device is completely sought, the specified data recording operation or data reproducing operation is performed.

An example of the position correction operation of the magnetic heads 5 and 6 is shown in FIG.

That is, first, a sector detection signal SKk is inputted (processed 301), and a predetermined coefficient A is applied to the inputted detection signal SKk.
Process 302) to calculate fine movement data RDk of the carriage 7 by adding the selected correction data DF to the value multiplied by
The calculated fine movement data RDk is output to the seek motor 8 to finely move the carriage 7 (process 303).

This operation is repeated until the data recording/reproducing operation is completed.

In this way, in this embodiment, using the correction data DF calculated prior to the data recording/reproducing operation, the detection signal S of the position information pattern SS obtained during the data recording/reproducing operation is
Since K is corrected and the magnetic heads 5 and 6 are moved using the correction result, the magnetic heads 5 and 6 are moved to the recording cylinder C.
L can be appropriately followed, and the reliability of data recording/reproducing operations can be improved.

In the embodiment described above, the position correction operation of the magnetic heads 5 and 6 is performed even during the seek operation, but it is also possible to not perform the position correction operation of the magnetic heads 5 and 6 during the seek operation. .

By the way, in the embodiment described above, the position correction operation of the magnetic head is performed using a sine wave signal having a frequency component of frequency f corresponding to the rotational speed of the magnetic disk 1 and a sine wave signal having a frequency component of frequency 2f. However, sine wave signals with other frequency components can be used. For example, a sine wave signal having a frequency component that is an integer multiple of the frequency f or a frequency component that is an integer fraction of the frequency f can also be used.

[Effects of the Invention] As explained above, according to the present invention, position servo information is corrected during data recording/reproduction using a sine wave signal of a plurality of frequency components of position servo information. The ability of the magnetic head to follow the cylinder can be improved, and data can be recorded/reproduced appropriately.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example of a magnetic disk according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing an example of a positional information pattern recorded on a recording cylinder, and Fig. 3 is a schematic diagram showing an example of a positional information pattern recorded on a recording cylinder. A graph illustrating the relationship between the deviation of the magnetic head from the position and the value of the reproduction signal of the position information pattern, FIG. 4 is a schematic diagram showing a magnetic disk device according to an embodiment of the present invention, and FIG. 6(a) is a graph diagram showing an example of a cosine wave signal; FIG. 6(b) is a graph diagram showing an example of a position signal; FIG. (C) is a graph showing an example of the value of the Fourier series of the frequency component of frequency f, Fig. 7 is a flowchart illustrating a part of the initial setting process, and Fig. 8 is a flowchart illustrating an example of processing during a seek operation. , FIG. 9 is a flowchart showing an example of a magnetic head position correction process. 10... Control unit, 14... Position information detection circuit, 19
...Waveform memory.

Claims (3)

[Claims] (1) Record a plurality of position servo information on the recording cylinder of each recording surface at predetermined angular intervals, perform Fourier transform on the reproduction signal of the position servo information, extract the fundamental frequency component of the reproduction signal, and extract it. The sine wave signal of the fundamental frequency component is stored in advance, and when recording/playing data,
Adjusts the position of the magnetic head in the radial direction of the magnetic disk, which records/reproduces data on the magnetic disk, based on a composite signal of the position servo information playback signal and the above sine wave signal. a signal extraction means for Fourier-transforming a reproduction signal of position servo information prior to a recording/reproduction operation, and extracting and storing a fundamental frequency component of the reproduction signal and a sine wave signal of a predetermined times the fundamental frequency component; a position adjustment signal calculation means for calculating a position adjustment signal for adjusting the position of the magnetic head in the radial direction of the magnetic disk based on a reproduction signal of the position servo information during reproduction and a composite signal of the plurality of sine wave signals; 1. A magnetic disk drive, comprising: control means for adjusting the position of the magnetic head in the radial direction of the magnetic disk in synchronization with the rotation of the magnetic disk using the position adjustment signal calculated by the position adjustment signal calculation means. (2) Record a plurality of position servo information on the recording cylinder of each recording surface at predetermined angular intervals, perform Fourier transform on the playback signal of the position servo information, and extract the fundamental frequency component of the playback signal. The sine wave signal of the fundamental frequency component is stored in advance, and when recording/playing data,
Adjusts the position of the magnetic head in the radial direction of the magnetic disk, which records/reproduces data on the magnetic disk, based on a composite signal of the position servo information playback signal and the above sine wave signal. Prior to the recording/reproducing operation, the reproduction signal of the position servo information for each recording surface is Fourier-transformed, and the fundamental frequency component of the reproduction signal and a sine wave signal of a frequency component that is a predetermined multiple of the fundamental frequency component are extracted and stored. a signal extraction means; and a position adjustment signal for adjusting the position of the magnetic head in the radial direction of the magnetic disk based on the reproduction signal of the position servo information during data recording/reproduction and the plurality of sine wave signals for each recording surface. a position adjustment signal calculation means for calculating a position adjustment signal according to a recording surface accessed by the magnetic head; and a position adjustment signal calculated by the position adjustment signal calculation means corresponding to a recording surface accessed by the magnetic head to adjust the position adjustment signal of the magnetic head in a radial direction of the magnetic disk in synchronization with the rotation of the magnetic disk. 1. A magnetic disk drive characterized by comprising a control means for adjusting the position of the magnetic disk drive. (3) Record a plurality of position servo information on the recording cylinder of each recording surface at predetermined angular intervals, perform Fourier transform on the playback signal of the position servo information, and extract the fundamental frequency component of the playback signal. The sine wave signal of the fundamental frequency component is stored in advance, and when recording/playing data,
A method for controlling a magnetic disk drive capable of replacing a recording medium, adjusting the position of a magnetic head in the radial direction of a magnetic disk for recording/reproducing data on a magnetic disk based on a composite signal of a reproduction signal of position servo information and the above-mentioned sine wave signal. In this step, prior to data recording/reproducing operations, a reproduced signal of position servo information is Fourier-transformed for each recording surface to extract a fundamental frequency component of the reproduced signal and a sine wave signal of a frequency component that is a predetermined multiple of the fundamental frequency component. A position adjustment signal for adjusting the position of the magnetic head in the radial direction of the magnetic disk based on the reproduction signal of the position servo information during data recording/reproduction and the plurality of sine wave signals mentioned above is transmitted to each recording surface. and adjusts the position of the magnetic head in the radial direction of the magnetic disk in synchronization with the rotation of the magnetic disk using the position adjustment signal according to the recording surface accessed by the magnetic head. Control method.