JPH09305964A - Magnetic disk and magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic disk in which a recording capacity is increased by a method wherein patterns at frequencies which are different on one side and on the other side with reference to the central line of a data track formed in a data storage area are formed inside a control-signal storage area and the occupied area of the patterns is reduced. SOLUTION: The position of a magnetic head 8 is set to be a just-on track when amplitudes of a pattern A and a pattern B detected by the magnetic head 8 are equal and when peak intervals of the amplitudes of both patterns are equal. That is to say, the pattern A is arranged on one side of the central line of a data track DT, the pattern B is arranged on the other side, and they are arranged in such a way that frequencies are different in the respective patterns on every track DT. Then, frequencies at the patterns A, B regarding a track DT in a track No.1 are set at f1, f3, the frequencies at the patterns A, B regarding a track No. I+1 are set at f2, f3, and frequencies at both patterns regarding a track No. I+2 are set at f2, f4. Thereby, the occupied area of the patterns is reduced, and a recording capacity can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk on which information such as data and programs is recorded and reproduced by a magnetic head mounted on a flying head slider, and a magnetic disk device equipped with the magnetic disk. Is.

[0002]

2. Description of the Related Art For example, in a computer system, a hard disk device is used as a magnetic disk device. In recent years, the recording capacity of hard disk devices has been increased, and for example, hard disk devices incorporating a pre-embossed magnetic disk have been developed. In this pre-embossed magnetic disk, a data recording area (hereinafter, referred to as a data zone) and a control signal recording area (hereinafter, referred to as a servo zone), each of which has an uneven portion, are radially formed.

That is, in the data zone, concentric circular data tracks for recording data and the like are formed as convex portions, and guard bands for separating adjacent data tracks are concave portions. Is formed. Further, in the servo zone, a gray code for specifying a data track, a clock mark that serves as a reference when generating a servo clock, and a fine pattern for obtaining track position information are formed. It may be formed by a convex portion or a concave portion.

Here, as the fine pattern,
An amplitude detection type pattern that detects the amplitude of the magnetization reversal and converts it into a position error signal is used. FIG. 16 is a plan view showing an example of a fine pattern formed on a conventional pre-embossed magnetic disk. This fine pattern is a burst pattern in which a reproduction signal of a constant frequency can be obtained by the magnetic head, and a plurality of rectangular embosses (four in this example) are arranged in parallel at regular intervals. The X pattern, the Y pattern, the A pattern, and the B pattern are arranged in this order.

Patterns A and B are on / off track confirmation patterns for confirming whether or not the magnetic head is correctly positioned on the data track. Amplitude and B of the signal by the A pattern reproduced by the magnetic head
The A pattern and the B pattern are arranged so that the position of the magnetic head is just on track when the signals of the patterns have the same amplitude. That is, the A pattern is arranged on one side of the center line of the data track, the B pattern is arranged on the other side, and the short side of each emboss of the A pattern and the B pattern is placed on the center line of the data track. It is located in.

However, since the A pattern and the B pattern have only amplitude information, it can be confirmed that the magnetic head is on-track or off-track.
It is impossible to determine which of the even and odd data tracks is located. Therefore, the X pattern and the Y pattern are provided to enable the even / odd track discrimination. The X pattern and the Y pattern are arranged so that there is a detection time difference between the signal amplitude of the X pattern reproduced by the magnetic head and the signal amplitude of the Y pattern. That is, the X pattern and the Y pattern are offset from each other on the center line of the data track, and the centers of the long sides of the embosses of the X pattern and the Y pattern are placed on the center line of the data track.

According to the magnetic disk having the fine pattern having such a structure, the signal waveform reproduced by the magnetic head is as shown in FIG. That is, the same figure (A)
Is a signal waveform when the magnetic head passes along the line AA shown in FIG. 16, and first, the amplitude v when the X pattern passes.
The signal waveform of 1 appears for a predetermined time, then the signal waveform of amplitude 0 when passing no pattern appears for a predetermined time, and finally the signal waveform of amplitude v2 when passing the A pattern and B pattern appears for a predetermined time. FIG. 16B shows a signal waveform when the magnetic head passes along the line BB shown in FIG. 16. First, a signal waveform with an amplitude of 0 when passing no pattern appears for a predetermined time, and then,
The signal waveform of the amplitude v1 when passing the B pattern appears for a predetermined time, and finally the amplitude v2 when passing the A pattern and the B pattern.
Signal waveform appears for a predetermined time.

With respect to these reproduction signals, a timing signal for specifying each pattern is output from the timing control circuit which constitutes the magnetic disk device. And
As shown in FIGS. 18A and 18B, according to the timing signal, each reproduction signal is full-wave rectified and integrated to output voltages Vx, Vy, Va, Vb corresponding to the amplitude of each reproduction signal. . Then, the even-odd track determination is performed by the voltages Vx and Vy, the on-track confirmation is performed by the voltages Va and Vb, and the tracking is controlled. That is, the voltage V
When x has a predetermined value and the voltage Vy is 0, it is determined that the track is an odd number, the voltage Vx is 0, and the voltage Vy is 0.
Has a predetermined value, it is determined that the track is an even number. Further, when the voltage Va is higher than the voltage Vb, it is confirmed that the track is off-tracked to the A pattern side, and the voltage Vb
Is larger than the voltage Va, it is confirmed that the B pattern side is off-track, and when the voltage Va and the voltage Vb are equal, it is confirmed that the track is on-track.

[0009]

In the fine pattern provided on the above-mentioned conventional magnetic disk, four patterns of X pattern, Y pattern, A pattern and B pattern are required, so that the data track becomes short. ,
There is a drawback that the recording capacity becomes small.

In view of the above points, an object of the present invention is to provide a magnetic disk capable of increasing the recording capacity of the magnetic disk and a magnetic disk device equipped with the magnetic disk.

[0011]

According to the present invention, the above object is a magnetic disk in which information is recorded and reproduced by a magnetic head mounted on a flying type head slider, and a data recording area and a control signal are provided. In a magnetic disk radially divided into recording areas, patterns of different frequencies on one side and the other side with respect to the center line of a data track provided in the data recording area are provided in the control signal recording area. It is achieved by

According to the above structure, since the pattern is such that the difference in frequency can be detected, the area occupied by the pattern can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. It is not limited to these forms unless otherwise stated.

FIG. 1 is a perspective view showing a structural example of a hard disk device which is an embodiment of a magnetic disk device of the present invention. In this hard disk device 1, a spindle motor 9 is provided on the back side of a flat surface of a housing 2 made of an aluminum alloy or the like, and a pre-embossed magnetic disk that is rotationally driven by the spindle motor 9 at a constant angular velocity. A disc 3 is provided. Further, an arm 4 is attached to the housing 2 so as to be swingable around a vertical axis 4a. A voice coil 5 is attached to one end of the arm 4, and a head slider 6 is attached to the other end of the arm 4. A magnet 7 is provided on the housing 2 so as to sandwich the voice coil 5.
a and 7b are attached. A voice coil motor 7 is formed by the voice coil 5 and the magnets 7a and 7b.

In such a configuration, the voice coil 5
When an electric current is supplied from the outside to the arm 4, the arm 4 rotates around the vertical axis 4a based on the force generated by the magnetic fields of the magnets 7a and 7b and the electric current flowing through the voice coil 5. Thereby, the head slider 6 attached to the other end of the arm 4 moves substantially in the radial direction of the magnetic disk 3. Therefore, the magnetic head 8 mounted on the head slider 6 performs a seek operation on the magnetic disk 3 to record and reproduce data on a predetermined data track of the magnetic disk 3.

FIG. 2 is a plan view showing an embodiment of a magnetic disk of the present invention, FIG. 3 (A) is a sectional view in the radial direction,
FIG. 2B is a sectional structural view in the circumferential direction. A data recording area (data zone) and a control signal recording area (servo zone) formed of concavo-convex portions are radially formed on a substrate 31 made of synthetic resin, glass, aluminum or the like of the pre-embossed magnetic disk 3. The magnetic film 32 is formed on the surface thereof.

That is, in the data zone, a concentric data track DT for recording data or the like is formed so as to be convex, and the adjacent data track DT is formed.
The guard band GB for dividing is formed as a concave portion. Further, in the servo zone, a servo pattern S such as a gray code for specifying the data track DT, a clock mark serving as a reference of the servo clock, and a fine pattern for obtaining track position information.
P is formed to be a convex portion or a concave portion.

According to such a magnetic disk 3, since the servo zone and the data zone are formed along the movement trajectory when the magnetic head 8 moves in the inner peripheral side direction or the outer peripheral side direction, the seek operation is performed. It is possible to maintain the isochronous property during operation, and to generate a PL for clock generation.
The lock release of the L circuit can be suppressed. In addition, azimuth loss can be suppressed.

The above-mentioned magnetic disk 3 can be manufactured by using optical technology, and the manufacturing method is shown in FIGS.
Will be described. First, the surface of the glass master 41 is coated with, for example, a photoresist 42. The glass master 41 coated with the photoresist 42 is mounted on a turntable 43 and rotated. For example, only a portion of the photoresist 42 which forms a concave portion is irradiated with a laser beam 44 to perform pattern cutting. After irradiating the laser beam 44, the photoresist 42 is developed to form a photoresist 4
The exposed portion 2 is removed. The surface of the glass master 41 from which the exposed portions of the photoresist 42 have been removed is plated with nickel 45. The nickel 45 is transferred to the glass master 4
The stamper 46 is peeled off from the stamper 1.

Next, the substrate 31 is formed using the stamper 46. Then, a magnetic film 32 is formed on the surface of the substrate 31 by sputtering or the like to form the magnetic disk 3. Then, the magnetic disk 3 is set in the magnetizing device 47 and magnetized by the magnetizing magnetic head 48.

FIG. 6 is a plan view showing an example of a fine pattern formed in the embodiment of the magnetic disk shown in FIG. In this fine pattern, at least one or more rectangular embosses are arranged in parallel with each other at a predetermined interval, and an A pattern and a B pattern are arranged in this order for each data track DT, and for each data track DT. The arrangement is such that the intervals, that is, the frequencies are arranged differently. The A pattern and the B pattern are on-track confirmation patterns for confirming whether or not the magnetic head 8 is correctly positioned on the data track DT (just on track).
It is an even-odd track discrimination pattern for discriminating whether or not it is located on T.

The amplitude of the A pattern detected by the magnetic head 8 is equal to the amplitude of the B pattern, and the A pattern and the B pattern are detected.
The position of the magnetic head 8 is just on-track when the peak intervals of the amplitude of the pattern are equal, and
The A pattern and the B pattern are arranged so that the data tracks DT are even or odd depending on the peak intervals of the amplitudes of the A pattern and the B pattern. That is, the A pattern is arranged on one side of the center line of the data track DT,
The B pattern is arranged on the other side, and the short sides of the embosses of the A pattern and the B pattern are arranged on the center line of the data track DT. Further, the frequency is different for each pattern of each data track DT. They are arranged differently.

In this example, the frequencies of the patterns A and B for the data track DT of the track number I are f1 and f3, and the data track D of the track number I + 1.
The frequencies of the A pattern and B pattern for T are f2 and f3, and the frequencies of the A pattern and B pattern for the data track DT of track number I + 2 are f2 and f4.
This combination is repeated for the other data tracks DT. In order to confirm that the position of the magnetic head 8 is in the just-on-track state when the peak intervals of the amplitudes of the A pattern and the B pattern are equal, it is set so that the difference between the frequencies of the patterns is not large. There is a need.

According to the magnetic disk 3 having the fine pattern having such a structure, the signal waveform reproduced by the magnetic head 8 is as shown in FIG. That is, FIG. 6A shows a signal waveform when the magnetic head 8 passes along the line AA shown in FIG. 6, and first, a signal waveform having an amplitude of va and a frequency of f1 when passing through the A pattern. For a predetermined time, and then a signal waveform having an amplitude of vb when passing through the B pattern and a frequency of f3 appears for a predetermined time. Fig. (B)
Is a signal waveform when the magnetic head 8 passes along the line BB shown in FIG. 6, and first, the signal waveform of the frequency f2 for which the amplitude is va at the time of passing the pattern A and the frequency f2 appears, and then The amplitude when passing through the B pattern is vb and the frequency f4
Signal waveform appears for a predetermined time.

With respect to these reproduction signals, a timing signal for specifying each pattern is output from the timing control circuit constituting the magnetic disk device as in the conventional case. Then, according to the timing signal, each reproduction signal is full-wave rectified and integrated to obtain the average signal amplitude of each reproduction signal, and the off-track amount is detected to confirm whether or not it is on-track. Here, generally, in magnetic recording, a reproduction signal has a wavelength characteristic, and the amplitude of the reproduction signal is different when the wavelength is different. In this case, when the average signal amplitudes are equal, it is not always on-track. For this reason, it is necessary to select a wavelength such that the difference between the average signal amplitudes is negligibly different and determine the reproduction signal.

As shown in FIG. 8, the reproduction signal is applied to a bandpass filter such as an analog filter or a digital circuit whose center frequency is the frequency of each reproduction signal, envelope detection is performed, and the amplitude levels are compared. The frequency of the reproduction signal is obtained, and whether the data track DT is even or odd is determined. For example, the amplitude levels Vaf1 and Vaf
2, by comparing Vbf3 and Vbf3, Vaf1> Va
At the time of f2, the reproduction signal of the A pattern has frequencies f1, V
When af1 <Vaf2, the reproduced signal of the A pattern has a frequency f2, when the reproduced signal of the B pattern has a frequency f3, when the reproduced signal of the B pattern has a frequency f3, and when Vbf3 <Vbf4,
The reproduced signal of the B pattern is obtained as the frequency f4.

Then, according to the discrimination table shown in FIG. 9, a combination of the frequencies of the reproduced signals of the A pattern and the B pattern, that is, when the frequency of the reproduced signal of the A pattern is f1 and the frequency of the reproduced signal of the B pattern is f3. Is an even number of data tracks DT, the frequency of the reproduced signal of the A pattern is f
When the frequency of the reproduced signal of the B pattern is 1 and the frequency of the reproduced signal of the A pattern is f2 and the frequency of the reproduced signal of the A pattern is f2 and the frequency of the reproduced signal of the B pattern is f3, the even number of data tracks is f3. When the frequency of the reproduced signal of the DT and A patterns is f2 and the frequency of the reproduced signal of the B pattern is f4, it is discriminated as an odd data track DT.

FIG. 10 is a block diagram showing a configuration example of the control unit of the hard disk device 1 shown in FIG. 1 in which the magnetic disk 3 having the fine pattern shown in FIG. 6 is incorporated. The recording / reproducing amplifier 11 of the control unit 10 amplifies the reproducing signal from the magnetic head 8 to generate a frequency discrimination circuit 12,
Output to the detection circuit 13 and the peak detection circuit 14. The frequency discriminating circuit 12 discriminates the frequency of the reproduction signal from the recording / reproducing amplifier 11 and outputs it to the amplitude comparing circuit 15. The amplitude comparison circuit 15 determines whether the data track DT is even or odd based on the frequency of the reproduction signal from the frequency discrimination circuit 12 and outputs it to the polarity switching circuit 16.

The detection circuit 13 includes a timing control circuit 17
A full-wave rectification of the reproduction signal from the recording / reproduction amplifier 11 is performed according to the timing signal from A
Output to the arithmetic circuit 18. The AB calculation circuit 18 calculates the difference between the voltage va and the voltage vb, which are the integrated output from the detection circuit 13, to obtain the off-track amount, and the polarity switching circuit 1
Output to 6.

On the other hand, the peak detection circuit 14 detects the amplitude peak from the reproduction signal from the recording / reproduction amplifier 11 and outputs it to the servo zone identification circuit 19. The servo zone identification circuit 19 outputs the servo zone identification signal to the timing control circuit 17 when the servo zone is identified by the peak of the amplitude of the reproduction signal from the peak detection circuit 14. The timing control circuit 17 outputs a timing signal for specifying each pattern of the reproduction signal to the detection circuit 13.

The polarity switching circuit 16 is the amplitude comparison circuit 1
The track position information is output to the tracking servo unit 20 according to whether the data track DT is even or odd from 5 and the off-track amount from the AB arithmetic circuit 18. The tracking servo unit 20 generates a tracking error signal based on the track position information from the polarity switching circuit 16 and drives the arm 4 in response to this. As a result, the magnetic head 8 is tracking-controlled to a predetermined radial position on the magnetic disk 3.

FIG. 11 is a plan view showing another example of the fine pattern formed in the embodiment of the magnetic disk of the present invention. In the fine pattern shown in FIG. 6, the A pattern is formed at frequencies f1 and f2, and the B pattern is formed at frequencies f3 and f4. However, in the fine pattern of this example, both the A pattern and the B pattern are formed at frequencies f1 and f2. are doing. That is, the frequencies of the A pattern and the B pattern of the data track DT of the track number I are f1 and f2, and the frequencies of the A pattern and the B pattern of the data track DT of the track number I + 1 are f2.
And f2, and the frequencies of the A pattern and the B pattern for the data track DT of the track number I + 2 are f2 and f.
1, the frequencies of the A pattern and the B pattern for the data track DT of the track number I + 3 are f1 and f1, and this combination is repeated for the other data tracks DT.

Then, according to the discrimination table shown in FIG. 12, A
A combination of the frequencies of the reproduced signals of the pattern and the B pattern, that is, when the frequency of the reproduced signal of the A pattern is f1 and the frequency of the reproduced signal of the B pattern is f2, an odd number of data tracks DT, the frequency of the reproduced signal of the A pattern. Is f
2 and the frequency of the reproduced signal of the B pattern is f2, an even number of data tracks DT, and the frequency of the reproduced signal of the A pattern is f2, and the frequency of the reproduced signal of B pattern is f1, the odd number of data tracks When the frequency of the reproduced signal of the DT and A patterns is f1 and the frequency of the reproduced signal of the B pattern is f1, it is determined that the data track DT is an even number.

FIG. 13 is a block diagram showing a configuration example of the control unit of the hard disk device 1 shown in FIG. 1 in which the magnetic disk 3 having the fine pattern shown in FIG. The parts are given the same reference numerals and the description thereof is omitted. Only the frequency discriminating circuit 112 of the control unit 110 differs from the control unit 10 of FIG. That is, FIG.
The control unit 10 of 0 discriminates four frequencies, but the control unit 110 discriminates two frequencies.

FIG. 14 is a plan view showing still another example of the fine pattern formed in the embodiment of the magnetic disk of the present invention. In the fine pattern shown in FIG. 6, the A pattern is formed with frequencies f1 and f2, and the B pattern is formed with frequencies f3 and f4. However, in the fine pattern of this example, the A pattern and the B pattern are not divided into a single pattern. Patterns with frequencies f1, f2f3 and f4
It is formed by. That is, the frequencies of the pattern relating to the data track DT of the track number I are f1 and f3, the frequencies of the pattern relating to the data track DT of the track number I + 1 are f3 and f2, and the frequencies of the pattern relating to the data track DT of the track number I + 2 are f2 and f4.
This combination is repeated for the other data tracks DT. According to the fine pattern having such a configuration, the area occupied by the pattern can be reduced.

FIG. 15 is a block diagram showing a configuration example of the control unit of the hard disk device 1 shown in FIG. 1 in which the magnetic disk 3 having the fine pattern shown in FIG. The parts are given the same reference numerals and the description thereof is omitted. The control unit 210 is provided with a two-frequency subtraction circuit 218 instead of the AB arithmetic circuit 18 of the control unit 10 of FIG. The detection circuit 213 detects the frequency of the reproduction signal from the frequency discrimination circuit 12 according to the timing signal from the timing control circuit 17 and outputs it to the two-frequency subtraction circuit 218. 2 frequency subtraction circuit 218
Calculates the difference in amplitude from the detection circuit 213 to obtain the off-track amount and outputs it to the polarity switching circuit 16.

The frequencies of the above-mentioned patterns are, for example, f1: 2.7 MHz (wavelength: 2.6 μm), f2: 3.
MHz (wavelength: 2.3 μm), f3: 3.3 MHz (wavelength: 2.1 μm), f4: 3.6 MHz (wavelength: 1.9)
.mu.m), the output difference is negligible in the actual electromagnetic conversion characteristics, and fine information can be obtained by comparing the average amplitude levels. Further, if there is such a frequency difference, it can be discriminated by filtering.

It should be noted that the servo disk is the same as the conventional magnetic disk.
If the fine length is allowed, the burst length of each fine pattern of the magnetic disk 3 can be doubled so that the S / N of the obtained signal can be improved and It can correspond to the track pitch of the density. Further, in the above-described embodiment, the pre-embossed magnetic disk has been described, but it is also applicable to a general planar magnetic disk.

[0039]

As described above, according to the present invention,
Since the area occupied by the pattern on the magnetic disk can be reduced, the area occupied by the data recording area can be increased to increase the recording capacity.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration example of a hard disk drive which is an embodiment of a magnetic disk drive of the present invention.

FIG. 2 is a plan view showing an embodiment of a magnetic disk of the present invention.

FIG. 3 is a sectional structural view of the embodiment of the magnetic disk shown in FIG.

FIG. 4 is a first diagram for explaining a manufacturing method of the embodiment of the magnetic disk shown in FIG.

FIG. 5 is a second diagram for explaining the manufacturing method of the embodiment of the magnetic disk shown in FIG.

6 is a plan view showing an example of a fine pattern formed in the embodiment of the magnetic disk shown in FIG.

FIG. 7 is a diagram showing an example of a signal waveform when the fine pattern shown in FIG. 6 is reproduced by a magnetic head.

8 is a waveform chart showing an example of processing the signal shown in FIG.

9 is a diagram showing an even / odd discrimination table based on the fine pattern shown in FIG.

10 is a configuration diagram showing an example of a control unit of the embodiment of the magnetic disk device shown in FIG. 1 having a built-in magnetic disk having the fine pattern shown in FIG.

11 is a plan view showing another example of a fine pattern formed in the embodiment of the magnetic disk shown in FIG.

12 is a diagram showing an even / odd discrimination table based on the fine pattern shown in FIG.

13 is a configuration diagram showing an example of a control unit of the embodiment of the magnetic disk device shown in FIG. 1 having a built-in magnetic disk having the fine pattern shown in FIG.

FIG. 14 is a plan view showing still another example of a fine pattern formed in the embodiment of the magnetic disk shown in FIG.

15 is a configuration diagram showing an example of a control unit of an embodiment of the magnetic disk device shown in FIG. 1 having a built-in magnetic disk having the fine pattern shown in FIG.

FIG. 16 is a plan view showing an example of a fine pattern formed on a conventional magnetic disk.

FIG. 17 is a diagram showing an example of a signal waveform when the fine pattern shown in FIG. 16 is reproduced by a magnetic head.

FIG. 18 is a waveform chart showing a processing example of the signal shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hard disk device, 2 ... Housing, 3 ...
Magnetic disk, 4 ... arm, 4a ... vertical axis, 5
... voice coil, 6 ... head slider, 6a
..Rail, 6b ... rail, 6c ... tapered part,
6d ... tapered portion, 7 ... voice coil motor, 7
a ... magnet, 7b ... magnet, 8 ...
Magnetic head, 9 ... Motor, 10, 110, 210
..Control units, 11 ... Recording / reproducing amplifiers, 12, 112
... Frequency discrimination circuit, 13, 213 ... Detection circuit,
14 ... Peak detection circuit, 15 ... Amplitude comparison circuit,
16 ... Polarity switching circuit, 17 ... Timing control circuit, 18 ... AB arithmetic circuit, 19 ... Servo zone identification circuit, 20 ... Tracking servo section, 3
DESCRIPTION OF SYMBOLS 1 ... Substrate, 32 ... Magnetic film, 41 ... Glass master, 42 ... Photoresist, 43 ... Turntable, 44 ... Laser beam, 45 ... Nickel, 46
... Stamper, 47 ... Magnetizing device, 48 ... Magnetizing magnetic head, 218 ... Two-frequency subtraction circuit

Claims (7)

[Claims] 1. A magnetic disk in which information is recorded and reproduced by a magnetic head mounted on a floating head slider, wherein the magnetic disk is radially divided into a data recording area and a control signal recording area. A magnetic disk, wherein a pattern of different frequencies on one side and the other side with respect to a center line of a data track provided in the data recording area is provided in the control signal recording area. 2. The magnetic disk according to claim 1, wherein the patterns are provided in different phases. 3. The magnetic disk according to claim 2, wherein the pattern is provided so as to repeat four kinds of frequencies. 4. The magnetic disk according to claim 2, wherein the pattern has two kinds of frequencies and is provided so as to have different frequencies in the same phase adjacent to each other. 5. The magnetic disk according to claim 1, wherein the patterns are provided in the same phase. 6. The magnetic disk according to claim 5, wherein the pattern is provided so as to repeat four kinds of frequencies. 7. A magnetic disk that is radially divided into a data recording area and a control signal recording area, a head slider that floats on the surface of the magnetic disk and moves in the radial direction of the magnetic disk, and the head slider. A magnetic disk device equipped with a magnetic head for recording and reproducing data and the like on the magnetic disk, wherein one side and the other side of the center line of the data track provided in the data recording area are provided. 2. A magnetic disk device, wherein patterns of different frequencies are provided in the control signal recording area.