JPH10134344A - Magnetic disk medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the data track density of a magnetic disk medium. SOLUTION: This magnetic disk medium is provided with a data signal recording area 11 where data track parts 13 in which information signal is recorded and/or reproduced and guard band parts 14 are formed and a control signal recording area where servo information or the like are recording and also is provided with a magnetic layer to be uniformly formed on these data signal recording area 11 and control signal recording area 12. Moreover, when the angle formed by a straight line connecting the rotational center of a rotary arm provided in a magnetic recorder and/or reproducing device and the middle point of the magnetic head provided at the top end of the rotary arm and the tangent line of the data track part 13 being directly under the magnetic head is defined as a skew angle θand a track pitch needed when that the Skew angle is 0 is defined as Tp and a track pitch in a length segment (r) in the radial direction of a magnetic recording medium 2 is defined as T(r), the data track part 13 has a track pitch to be formed by Tpcosθ-0.1(μm)<=T (r)<=Tpcosθ+0.1(μm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk medium incorporated in a hard disk drive or the like and recorded and / or reproduced by a magnetic head. More specifically, the present invention relates to a magnetic head mounted on the tip of a rotating arm. Or, it relates to a magnetic disk medium on which reproduction is performed.

[0002]

2. Description of the Related Art For example, in a computer system, a hard disk device is used as a recording and / or reproducing device for a magnetic disk. This hard disk device has realized a reduction in size, an increase in capacity, and a reduction in unit cost of bits by improving the surface recording density of a magnetic disk medium.

The magnetic disk medium has two methods for improving the areal recording density: a method for improving the linear recording density, and a method for improving the data track density by narrowing the track width. As a method for improving the linear recording density, MR (m
Agento-effective inductive composite head and PRML (partial-respon)
A signal processing method such as se-maximum-likelihood has been proposed. On the other hand, to improve the data track density, a PERM (Pre-Em) shown in FIGS. 11 and 12 for improving the track density by forming a physical uneven portion on the magnetic disk medium is used.
A magnetic disk medium 100 such as a "bossed-Rigid-Magnetic" disk has been proposed.

The magnetic disk medium 100 shown in FIGS. 11 and 12 is formed of a substrate 101 made of synthetic resin, glass, aluminum, or the like. The substrate 101 made of a synthetic resin or the like has a data recording area 102 and a control signal recording area 103 formed by transferring a concavo-convex pattern on the surface by a molding die apparatus. A magnetic layer 104 is formed on the data recording area 102 and the control signal recording area 103 to enable recording and / or reproduction of an information signal.

The data recording area 102 includes a data track portion 105 formed concentrically as a convex portion and a data track portion 10 formed concentrically as a concave portion and adjacent to the data track portion 10.
5 is provided.

The data track section 105 has a constant track pitch and track width concentrically from the innermost periphery to the outermost periphery of the magnetic disk medium 100.
The data track portion 105 has a track pitch by being formed by a convex portion. The track pitch is a distance from a track center to a track center adjacent thereto, and is formed to be constant on the magnetic disk medium 100 from the outer peripheral portion to the inner peripheral portion. For example, FIG.
Magnetic disk medium shown in 2 100, the outer peripheral side of the data track portion 105a, 105b and the track pitch T _a which is formed by 105c, the inner periphery side of the data track section 105d, the track pitch formed by 105e and 105f when a T _b, and is formed such that T _a = T _b.

A magnetic layer 104 is formed on the data track portion 105, and information is recorded by rotating the magnetization direction of the magnetic layer 104. In the data track section 105, at the time of reproduction, recorded information is detected as a leakage magnetic field by a magnetic head provided in a hard disk device.

The guard band 106 is formed in a recess between the data tracks 105, and is formed to be narrower than the width of the data tracks 105. The guard band 106 eliminates the disadvantage that extra recording is caused by the leakage magnetic field generated from the side of the head gap of the magnetic head. Therefore, the guard band unit 106 reduces noise by reducing unnecessary recording and ensures a high S / N.

The control signal recording area 103 includes a gray code (not shown) for determining the data track portion 105 in a radial pattern, a clock mark for dividing one circumference at equal intervals, a wobbled mark for tracking control of the magnetic head, and the like. Are formed so as to be convex portions. In the control signal recording area 103, servo pits, which are spaces for separating the codes and the like, are formed so as to be recessed.

The control signal recording area 103 has a function of causing the magnetic head to accurately follow the data track section 105. The control signal recording area 103 includes the magnetic disk medium 1
A radial pattern is formed on the surface of the substrate 00 as an uneven portion. The control signal recording area 103 thus formed forms a plurality of sectors 108 arranged concentrically. This sector 1
08 is formed by vertically dividing the data track portion 105 by unevenness.

The magnetic disk medium 1 configured as described above
00 is a data signal recording area 10 formed as a projection.
2 is provided with a data track portion 105 and a guard band portion 106 formed as a concave portion, and further formed by a control signal recording area 103 for surely scanning the magnetic head over the data track portion 105. Since the magnetic layer 104 is formed on the control signal recording area 103 and the control signal recording area 103, it is possible to reliably record and / or reproduce the information signal on the data track section 105 by the magnetic head 110 provided in the hard disk device. It is.

In this hard disk drive, as shown in FIG. 13, a rotary arm having a length L is rotated around a point O. The rotating arm positions a magnetic head mounted on the tip on the data track section 105, and performs recording and / or reproduction of an information signal.

Since the magnetic disk medium 100 is formed with a constant track width and an equal track pitch,
When the magnetic head 110 is moved from the position 110a to the position 110d in the direction A of FIG. 13, the Skew angle θ (the straight line L connecting the rotation center of the rotating arm and the magnetic head 110)
And data track portion 1 immediately below magnetic head 110
05) are θ _a , θ _b , θ _c ,
theta _d, and becomes gradually larger. Also, the magnetic head 11
0 viewed from the effective track width, as compared with the track width t _a data track portion 105a data track portion 105b when the Skew angle theta = 0, 105c, 105d
Each track _{width, t b, t c, t} d becomes gradually smaller.

[0014]

Therefore, in such a magnetic disk medium, when recording and / or reproduction is performed, the track pitch is reduced in spite of the fact that the effective track width viewed from the magnetic head is reduced. Has a problem that it is useless in forming the concavo-convex pattern.

In view of the above problems, the present invention provides a magnetic disk medium having an improved surface recording density by improving the density of a data track portion by using a magnetic disk medium having a changed track pitch. Aim.

[0016]

According to the present invention, there is provided a magnetic disk medium according to the present invention, wherein a data track is formed as a concavo-convex pattern on a surface of a magnetic disk medium, on which information signals are recorded and / or reproduced. A data signal recording area in which a guard band portion formed concentrically as a concave portion is formed, a control signal recording area in which servo information and the like are formed in a radially uneven pattern on the surface, and data. A magnetic layer uniformly formed on the signal recording area and the control signal recording area, and the data track portion is provided on a rotating arm provided in a magnetic disk recording and / or reproducing apparatus and on a tip of the rotating arm. The angle between the straight line connecting the magnetic head and the midpoint and the tangent to the data track portion immediately below the magnetic head is defined as Skew angle θ,
When ew angle θ = 0, the required track pitch is Tp, and when the track pitch in the radial length line segment r of the magnetic disk medium is T (r), Tpcos θ−
0.1 (μm) ≦ T (r) ≦ Tpcosθ + 0.1 (μ
m).

The magnetic disk medium thus configured is formed by changing the track pitch concentrically formed on the surface, thereby improving the track density and the surface recording capacity. Is possible. [Detailed description of the invention]

Hereinafter, a magnetic disk medium according to the present invention will be described in detail with reference to the drawings.

The embodiments described below are technically limited, but can be modified without departing from the spirit of the present invention.

The magnetic disk medium 2 according to the first embodiment of the present invention is mounted on a hard disk drive 1 as shown in FIG.

In the hard disk drive 1, a spindle motor 3 is disposed behind a plane portion of a housing 4 formed of an aluminum alloy or the like, and a magnetic disk rotated at a constant angular velocity by the spindle motor 3 is provided. The medium 2 is loaded. Further, a rotating arm 5 is attached to the housing 4 so as to be swingable around a vertical axis 6. A voice coil 7 is attached to one end of the rotary arm 5, and a voice coil motor 9 is formed by magnets 8a and 8b so as to sandwich the voice coil 7.

In such a configuration of the hard disk drive 1, the voice coil motor 9 includes the magnets 8a and 8a.
It rotates around the vertical axis 6 based on the force generated by the magnetic field b and the current flowing through the voice coil 7. As a result, the magnetic head 10 attached to the head slider mounted on the tip of the rotary arm 5 is moved substantially in the radial direction A of the magnetic disk medium 2. The magnetic head 10 is, for example, an MIG (metal-in-gap) head or the like, and scans the data track section 13. Therefore, this magnetic head 10 is
Record / reproduce data or the like.

The magnetic disk medium 2 recorded and / or reproduced by the hard disk device 1 as described above is formed on a substrate 16 made of synthetic resin, glass, aluminum or the like. This magnetic disk medium 2 is shown in FIGS.
As shown in the figure, the data recording area 11 formed by the uneven portion
And a control signal recording area 12, and a magnetic layer 15 is formed on the surface thereof.

In the data recording area 11, a concavo-convex pattern is formed concentrically on the magnetic disk medium 2, and a convex portion as a data track portion 13 for recording signal information and a concave portion as a guard band portion 14 are formed. You. The magnetic head 10 scans the data recording area 11 to record and / or reproduce an information signal.

The data track portion 13 is formed by a convex portion formed on the surface of the substrate 16 as shown in FIG. The data track portion 13 has a track pitch by being formed by a convex portion. The track pitch is a distance T between a track center and an adjacent track center, and is formed by changing according to a radial length on the magnetic disk medium 2. Magnetic disk medium 2 shown in FIG. 3 for example, the track pitch T _a which is formed by the data track portion 13a and the data track section 13b of the outer peripheral portion side, more of the inner periphery side of the data track portion 13c and a data track portion 13d when the track pitch T _b which is formed, is formed such that T _a> T _b.

A magnetic layer 15 is formed on the data track portion 13 and the guard band portion 14 as shown in FIG. 3, and information signals are recorded by changing the magnetization direction of the magnetic layer 15. . The data track section 13 reproduces the recorded information by detecting a leakage magnetic field by the magnetic head 10.

The guard band portion 14 is formed by a concave portion between the data track portions 13. The guard band portion 14 has the magnetic layer 15 formed therein, but is recessed from the data track portion 13 so that a spacing loss occurs, and recording and reproduction is hardly performed on the guard band portion 14. Therefore, the guard band portion 14
Conventionally, when recording an information signal with the magnetic head 10, the magnetic head 10 has the advantage of reducing the noise component recorded by the leakage magnetic field generated from the side surface of the head gap and improving the SN ratio. ing.

The control signal recording area 12 is an uneven portion formed radially from the center of the magnetic disk medium 2, and divides the data track section 13 to form a plurality of concentrically arranged sectors. This sector is formed by vertically dividing the data track portion 13 by unevenness, and an information signal is recorded for each sector.

The control signal recording area 12 includes a gray code (not shown) for radially identifying a data track number, a clock mark for dividing one circumference at equal intervals, and a wobbled mark for tracking control of the magnetic head 10. Are formed so as to form, for example, a convex portion, and the space for separating the code or the like is formed to be a concave portion. Therefore, the control signal recording area 12 has a function of causing the magnetic head 10 to accurately follow the data track section 13.

The magnetic disk medium 2 configured as described above
When data is recorded and / or reproduced with respect to the data track section 1, as shown in FIG.
3a to the adjacent data track portion 13b.

At this time, the rotating arm 5 has a seek angle φ
And the magnetic head 10 is moved to the data track portion 13a.
The data track 13b is scanned from above. The seek angle φ is an angle that allows for a line segment of a length dimension Tp including a magnetic head gap separated from the rotation center O of the rotation arm 5 by the length dimension L of the rotation arm 5. This Tp is
This is the required track pitch when the Skew angle θ of the magnetic head 10 is 0. The skew angle θ is equal to the rotation arm 5
A straight line connecting the center point O of rotation of the magnetic head and the midpoint of the magnetic head 10;
The angle formed by the tangent of the data track portion 13 immediately below the magnetic head 10.

The skew angle θ is such that the rotation arm 5 is driven to rotate in the direction A at the seek angle φ and the data track portion 1 is rotated.
When scanning the adjacent data track portion 13b from 3a, an angle θ is generated. At this time, the track pitch T
(R) is formed with the dependency of cos θ on Tp, and is expressed by the equation T (r) = Tpcos θ.

That is, the magnetic disk medium 2 is
The track portion is formed while changing the track pitch T (r) according to the radial length r on the magnetic disk medium 2.

The magnetic disk medium 2 configured as described above
FIG. 5 shows an example when the magnetic head 10 is scanned above. FIG. 5 shows the data track section 13 and the rotating arm 5.
It is a schematic diagram showing a positional relationship with. Origin A (0,0)
Indicates the rotation center of the magnetic disk medium 2. Also, point B
(D, 0) indicates the center of rotation of the rotary arm 5, and the point C
(X, y) shows the position of the magnetic head 10 provided at the tip of the rotating arm 5 and the data track portion 13 immediately below the magnetic head 10. The distance r from the origin A is the rotation center A (0, 0) of the magnetic disk medium 2.
To the radial dimension of an arbitrary data track portion 13. The skew angle θ is defined by the rotation center B (d, 0) of the rotary arm 5 and the position C (x, y) of the magnetic head.
And the angle formed by the tangent component of the track immediately below the magnetic head 10. The rotation arm length L indicates the length dimension of the rotation arm 5, and b indicates a straight line A with the rotation arm 5.
The angle formed with B is shown.

Therefore, the Skew angles θ, a and b are
In such a positional relationship, the rotating arm 5, the magnetic head 10,
When the magnetic disk medium 2 is provided, θ = π−ab
− (Π / 2), a = tan ⁻¹ (y / x), b = tan ⁻¹
[Y / (d−x)].

Where x ² + y ² = r ² , (x−d) ² + y
² = is L ^2. Therefore, x = (d ² + r ² + L ² ) /
2d, y = [r ² − (d ² + r ² + L ² ) / 4d ² ] ^1/2

The skew angle θ and the track pitch T
The calculated value of (r) is shown in FIGS. The calculation conditions are as follows: the outer radius of the magnetic disk is 26.2 mm;
The calculation was performed assuming that the outer radius of the magnetic disk was 11.82 mm, the length L of the rotating arm was 26.5 mm, and the track pitch Tp when the Skew angle θ = 0 was 4.8 μm.

FIG. 6 is a view showing the dependence of the Skew angle θ on the radius r by setting the Skew angle θ on the vertical axis and the length r in the radial direction of the magnetic disk medium 2 on the horizontal axis. . The dependence of the Skew angle θ on the radius r is substantially proportional to the radius r of the magnetic disk medium 2 as a whole.

FIG. 7 is a diagram showing the dependence of the track pitch on the radius r with the vertical axis representing the track pitch and the horizontal axis representing the radial length r of the magnetic disk medium 2. In FIG. 7, one track pitch Tpco
sθ indicates the radius dependency of the magnetic disk medium 2 calculated, and the other track pitch T (r) is the radius r of the magnetic disk medium 2 actually formed on the magnetic disk medium 2 by the laser cutting device 30 described later. Shows the dependency of The dependency of the track pitch on the radius r Tpco
sθ becomes smaller as a whole by drawing a gentle arc.

Therefore, this magnetic disk medium 2
The data track portion 13 and the guard band portion 14 are calculated based on the track pitch Tpcos θ calculated by the equation 1.
Is formed. As shown in FIG. 4 described above, the track pitch T (r) is set such that the magnetic heads 10a, 10b, 10c, and 10d are arranged on the data track portion 13 in the inner circumferential direction of the magnetic disk medium 2 at 13a, 13b, and 13c. , 13d, Tp, Tpcos θ _b , Tpco
sθ _c , Tpcos θ _{d and} narrow.

The magnetic disk medium 2 thus formed
Can record and / or reproduce signal information recorded on the data track section 13 while keeping the seek angle φ of the rotating arm 5 constant, and can improve the number of data tracks in the radius r direction and the surface recording density. It is planned.

The manufacturing process of such a magnetic disk medium 2 is performed according to the process outline diagram shown in FIG. The manufacturing process of the magnetic disk medium 2 includes a glass master disk polishing / cleaning step S1 of polishing the glass master disk and precision cleaning the glass master disk.
A coupling agent applying step S2 for applying a coupling agent on the glass master; a photosensitive resist applying step S3 for forming a photosensitive resist layer on the glass master; and a laser for forming an uneven pattern on the photosensitive resist layer by laser cutting. A cutting step S4, a developing step S5 for developing a concavo-convex pattern, an electroless plating manufacturing step S6 for forming electroless plating on the photosensitive resist layer, a plating manufacturing step S7 for plating on the photosensitive resist layer, The method includes a disk master forming step S8 for transferring a concave / convex pattern onto a plastic substrate by separating from a glass master, and a magnetic layer forming step S9 for forming a magnetic layer 15 on the plastic substrate 16.

In the step S1 of polishing and cleaning the glass master, the glass master is polished to obtain a flat and stable glass master having good adhesion to the photosensitive resist when the photosensitive resist layer is formed. Chemical, such as scratches, burns, etc.
Remove the physically altered layer. And the glass master
Precise cleaning with pure water removes deposits on the glass master, such as oil and dust.

In the coupling agent application step S2, a coupling agent is applied in order to increase the lipophilicity of the surface of the glass master and improve the adhesion between the photosensitive resist layer and the glass master.

In the photosensitive resist coating step S3, the glass resist is placed on a turntable (not shown), and the photosensitive resist is applied by a spin coating method in which the photosensitive resist layer is uniformly applied by centrifugal force due to the rotation while the glass master is rotated. Apply 300 nm thick. Further, in order to improve the adhesion of the photosensitive resist layer, baking is performed at 30 ° C. for 30 minutes in a furnace to evaporate the resist solvent.

In the laser cutting step S4, a laser beam is focused on a spot having a diameter of 0.4 μm by a laser cutting device 30 described in detail below, and the photosensitive resist layer formed on the glass master is irradiated with the laser beam. At this time, in the concave / convex pattern, a latent image is formed on the photosensitive resist layer by a format signal that makes the track pitch a constant seek angle based on the calculation results of Equation 1 and Equation 1.

In the developing step S5, the data recording area 11 and the control signal recording area 12, which are the concavo-convex pattern on which the latent image has been formed in the laser cutting step S4, are revealed.

The electroless plating manufacturing step S6 is performed to make the photosensitive resist layer, which is a non-conductor, conductive.
Electroless plating of a thick conductive nickel-phosphorous alloy film.

In the plating production step, nickel is electroformed on the photosensitive resist layer on the surface of the glass master which has been converted into a conductor in the electroless plating production step S6 to produce a nickel plate having a thickness of 400 μm.

Then, the nickel plate produced in the plating producing step S7 is separated from the glass master and mounted on a molding die apparatus.

The disk substrate forming step S8 is performed by transferring an uneven pattern formed on the surface of a nickel plate mounted on a molding die device to a plastic plate, thereby forming a plastic substrate 16 serving as a substrate of the magnetic disk medium 2. Is prepared.

In the magnetic layer forming step S9, a magnetic layer of cobalt platinum chrome or cobalt platinum is sputtered on the surface of the plastic substrate 16 on which the concavo-convex pattern has been transferred in the disk substrate forming step S9, and then a carbon protective layer is formed by sputtering. .

Therefore, the magnetic disk medium 2 is provided with the magnetic layer 15 on the plastic substrate 16 on which the concavo-convex pattern is formed by such a magnetic disk medium manufacturing process.
Is completed by forming

In the above-described laser cutting step S4, the photosensitive resist layer on the glass master 31 is irradiated with a laser beam based on the calculated values of the equations (1) and (1) so that the seek angle φ of the rotary arm 5 is always constant. To make the track pitch T (r) a latent image.

Since the latent image of the track pitch T (r) is formed by the laser cutting device 30, the latent image is formed not in the calculated track pitch Tpcos θ but in a stepwise manner as shown in FIG.

This laser cutting device 30 is similar to that shown in FIG.
As shown in FIG. 2, a turntable 32 for rotating the glass master 31 at a constant speed, a rotary encoder 33 for outputting a constant pulse signal based on the rotation cycle of the turntable 32, and a turntable 32 and a rotary encoder 33 And a spindle motor 34 for simultaneously rotating the motors. In addition, the laser cutting device 30
Are an exposure laser 35 for emitting a laser beam applied to the glass master 31, and a pattern signal generator 36 for converting an output signal from the rotary encoder 33 into a control signal.
An acousto-optic modulator 37 for controlling ON / OFF of the laser beam based on a signal from the pattern signal generator 36, a mirror 38 for bending the laser beam passing through the acousto-optic modulator 37 by 90 °, An objective lens 39 for condensing the laser beam bent by the mirror 38 on the glass master 31 is provided.

In the laser cutting apparatus 30 thus configured, the pattern signal generator 36 generates a signal synchronized with the pulse signal of the rotary encoder 33, and drives the acoustic engineering modulation element 37 by the signal. The laser light modulated by the optical modulation element 37 is focused on the glass master 31 by the objective lens 39. Then, the laser cutting device 30 scans the objective lens 39 at a constant speed from the outer peripheral side to the inner peripheral side in the radial direction of the glass master 31 and scans the laser light on a straight line passing through the rotation center of the glass master 31. A laser beam is focused on the glass master 31 on the turntable 32 while moving at a constant speed, thereby forming a latent image of the concavo-convex pattern.

Therefore, the laser cutting device 30
Performs the latent image formation of the track pitch T (r) so as to control the feed distance of the objective lens 39 and follow the track pitch Tpcos θ of the calculated value shown in FIG. While the turntable 32 makes one rotation, the objective lens 39 is fed in a fixed amount in the radial direction of the glass master 31. The track pitch T (r) is limited by the feed distance.

Therefore, the track pitch Tpcos θ calculated by the calculation is equal to the track pitch Tp actually formed by the laser cutting device 30 as a latent image.
The difference ΔTp = T (r) −Tpcos θ from (r) occurs.

Generally, it is possible to make the moving distance of the objective lens 39 less than 0.2 μm per rotation of the turntable 32 provided in the laser cutting device 30.

Therefore, the laser cutting device 30
Is obtained by changing the track pitch T (r) so as to follow the track pitch Tpcos θ of the calculated value.
In the case where the laser beam is irradiated on the laser beam 1 and the distance for moving the objective lens 39 per turntable rotation is 0.2 μm, the track pitch T (r) (μm) becomes Tpcos θ− as shown in FIG. 0.1 ≦ T (r) ≦ T
The track pitch is latently imaged in the range of pcos θ + 0.1.

Thus, Tpcos θ−0.1 ≦ T
The track pitch T (r) formed in the range of (r) ≦ Tpcos θ + 0.1 is determined by the laser cutting device 3
Since the latent image is formed by the laser light so as to follow the track pitch Tpcos θ of the calculated value by 0, more tracks can be formed on the magnetic disk medium 2 and the recording capacity can be increased.

In the laser cutting step S4, while the turntable 32 makes one rotation, the glass master 3
The feed distance in the radial direction r of 1 is not limited to 0.2 μm.

Therefore, the calculated value of track pitch Tp
If the laser beam is applied to the glass master 31 while changing the track pitch T (r) so as to follow cos θ, the distance that the objective lens 39 moves per rotation of the turntable is 0.05 μm. As shown in FIG. 10, T (r) cos θ−0.025 ≦ T (r) ≦ Tp
track pitch T (r) in the range of cos θ + 0.025
(Μm) is formed as a latent image.

In the magnetic disk medium 2 manufactured through such a laser cutting step S4, the track density of the data track portion 13 formed concentrically can be further improved.

The magnetic disk medium 2 has, for example, a length in the diameter direction of 1.81 inches and a length of 0.05 μm.
The total number Na of the data track portions 13 when the format is changed by changing the track pitch at intervals is the glass master 3
1 of the radius of the outer peripheral portion and R _o, the radius of the inner peripheral portion R _i 11
When _{820μm, Na = (R o -R} i) / T (r) becomes, is estimated as follows.

The total number of data tracks 13 is Na = (14
182.2-11820) /4.65+ (16036-
14182.2) /4.6+ (17683.1-160)
36) /4.55+ (19172.6-17682) /
4.5+ (20997.1-19172.6) /4.4
5 = 2014.

On the other hand, the number Np of data tracks of the magnetic disk medium 100 formed at a constant track pitch from the innermost peripheral portion to the outermost peripheral portion is determined by setting the radius of the outer peripheral portion of the glass master to R.
_o, and the radius of the inner periphery is R _i , Np = (R _o −
R _i ) / Tp, and Np = (21000-1182)
0) /4.8=1912. Therefore, the magnetic disk medium 2 has about 5% increase in the number of data tracks compared to the magnetic disk medium 100 formed at a fixed track pitch.

Therefore, the laser cutting step S4
In the above, by moving the objective lens 39 at 0.05 μm per rotation with respect to the calculated value, it is possible to further improve the track density. In the magnetic disk medium 2, the track density is improved, so that the areal recording density can be improved.

The magnetic disk medium 2 described above can be recorded and / or reproduced by the hard disk drive 1 having the magnetic head 10 mounted on the head slider at the tip of the rotary arm 5 described above. It is.

[0071]

As described in detail above, the magnetic disk medium thus configured is formed as a concavo-convex pattern on the surface as a concavo-convex pattern, and a data track on which information signals are recorded and / or reproduced. And a control signal recording area having a data signal recording area in which a guard band portion formed concentrically as a concave portion is formed, or a servo information or the like is recorded on the surface as a radially uneven pattern. And a magnetic layer uniformly formed on the data signal recording area and the control signal recording area, and the data track portion includes a rotating arm provided in a magnetic disk recording and / or reproducing apparatus and a tip of the rotating arm. The angle between a straight line connecting the magnetic head provided at the center and the tangent to the data track portion immediately below the magnetic head is defined as the Skew angle θ.
And the track pitch required when the Skew angle θ = 0 is Tp, and the length line segment r in the radial direction of the magnetic disk medium
Where T (r) is the track pitch at
osθ-0.1 (μm) ≦ T (r) ≦ Tpcosθ +
It has a track pitch formed at 0.1 (μm).

Therefore, since such a magnetic disk medium has a track pitch formed by changing the length in the radial direction, the track density can be improved, and It is possible to improve the areal recording density of the disk medium.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a hard disk drive loaded with a magnetic disk medium according to the present invention.

FIG. 2 is a plan view showing the magnetic disk medium.

FIG. 3 is a sectional view of a main part showing a data recording area of the magnetic disk medium.

FIG. 4 is a schematic plan view showing how a magnetic head scans a data recording area of the magnetic disk medium.

FIG. 5 is a schematic diagram showing a positional relationship between a data track portion of the magnetic disk medium and a rotating arm.

FIG. 6 is a diagram showing the radius dependence of the Skew angle θ when the vertical axis is the Skew angle θ and the horizontal axis is the radial length r of the magnetic disk medium.

FIG. 7 is a diagram showing a calculation result when the vertical axis is a track pitch of a magnetic disk medium and a horizontal axis is a length dimension in a radial direction of the magnetic disk medium, and a radius dependency of an actual track pitch.

FIG. 8 is a schematic view showing a magnetic disk medium manufacturing process.

FIG. 9 is a schematic view of a laser cutting device used in a laser cutting step.

FIG. 10 shows a vertical axis representing a track pitch of a magnetic disk medium,
FIG. 7 is a diagram illustrating a calculation result when the horizontal axis is a length in a radial direction of a magnetic disk medium and a radius dependency of an actual track pitch.

FIG. 11 is a schematic plan view showing a conventional magnetic disk medium.

FIG. 12 is a sectional view of a main part showing a data signal recording area of a conventional magnetic disk medium.

FIG. 13 is a schematic plan view showing how a magnetic head scans a data recording area of a conventional magnetic disk medium.

[Explanation of symbols]

1 hard disk device, 2 magnetic disk medium, 5
Rotating arm, 10 magnetic head, 11 data signal recording area, 12 control signal recording area, 15 magnetic layer, 13
Data track section, 14 guard band section

Claims (1)

[Claims] 1. A magnetic disk medium in which an information signal is recorded and / or reproduced by a magnetic head provided at a tip of a rotating arm mounted on a magnetic disk recording and / or reproducing apparatus, wherein the magnetic disk medium has a surface protruding concentrically. Signal signal recording region formed of a data track portion on which an information signal is recorded and / or reproduced and a guard band portion formed concentrically as a concave portion, or a radially uneven pattern formed on the surface. A control signal recording area in which a servo signal is recorded, and a magnetic layer uniformly formed on the data signal recording area and the control signal recording area. as well as/
Alternatively, Skew is an angle formed by a straight line connecting the rotation center of the rotating arm provided to the reproducing device and the midpoint of the magnetic head provided at the tip of the rotating arm and a tangent to the data track portion immediately below the magnetic head. Angle θ, S
The above track pitch required when the ke angle θ = 0 is T
p, and a radial line segment r in the radial direction of the magnetic disk medium
Where T (r) is the above track pitch, Tpcos θ−0.1 (μm) ≦ T (r) ≦ Tpcos
A magnetic disk medium formed so as to satisfy θ + 0.1 (μm).