JP2001167418A - Head slider and disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a disk shaped recording medium or the like from being damaged due to contact between a head slider and the disk shaped recording medium or the like. SOLUTION: This device is provided with rails 12, 13 which are formed projectingly from the surface facing the disk shaped recording medium and projecting parts 15 whose height are lower than the height of the rails 12, 13 and which are provided at corner parts positioned outside the rails 12, 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head slider which flies at a small interval on a signal recording surface of a rotating disk-shaped recording medium during recording and / or reproduction, and a disk drive provided with such a head slider. Related to the device.

[0002]

2. Description of the Related Art For example, a hard disk drive (hereinafter referred to as an HDD) has advantages such as high speed, large capacity and relatively low cost, and is used as a recording / reproducing device built in or externally connected to a personal computer or the like. Have been.

In this HDD, as shown in FIG. 18, a head slider 102 attached to a tip end of a suspension 101 slightly floats on a signal recording surface of a magnetic disk 100 rotated and driven in an arrow R direction. A magnetic head mounted on the head slider 102 records or reproduces signals on the magnetic disk 100.

As shown in FIG. 19, the head slider 102 is located on the surface facing the magnetic disk 100, at a position slightly closer to the center than the end portions 106 and 107 on both sides of the head slider 102, and is substantially parallel. Two rails 103,
A projection 104 is formed. Also, two rails 10
A magnetic head 105 is attached to one of the magnetic heads 3 and 104. The head slider 102 receives a floating force on the two rails 103 and 104 by the airflow in the direction of arrow Y generated on the signal recording surface of the rotating magnetic disk 100, and the floating force of the magnetic disk 100 It floats at a very small interval from the signal recording surface.

In this HDD, the above-mentioned head slider 102 is slightly floated from the signal recording surface of the magnetic disk 100, so that the magnetic head 105 mounted on the head slider 102 comes into contact with the magnetic disk 100 and wears out. To prevent them from getting lost.

[0006]

By the way, the above-mentioned H
In the DD, the magnetic disk 100 is rotationally driven at a high speed in order to make the head slider 102 fly. Therefore, in the HDD, when the head slider 102 comes into contact with the magnetic disk 100 rotating at a high speed, there is a possibility that the magnetic head 105 mounted on the head slider 102, the magnetic disk 100, and the like may be significantly damaged. For this reason, it is necessary to minimize external vibrations and shocks to the HDD.

However, in recent years, with the spread of so-called portable computers such as notebook personal computers and hand-held personal computers, cases where these portable computers are taken out of the door and used have started to increase. For this reason, it is very difficult to use the HDD such that it does not give any vibration or impact when used as a recording / reproducing device of these portable computers.

Here, when vibration or shock is applied to the HDD from the outside, first, as shown in FIG. 20A, the head slider 102 separates from the signal recording surface of the magnetic disk 100. Jump in the direction. Then, the head slider 102 approaches the signal recording surface side of the magnetic disk 100 this time due to the return rigidity of the suspension 101, as shown in FIG. At this time, since the head slider 102 has a free posture, it cannot land in a parallel posture on the signal recording surface of the magnetic disk 100.

For this reason, in the HDD, as shown in FIGS. 20 (c) and 21, the ends 106 on both sides of the head slider 102 are used instead of the two rails 103 and 104 formed on the head slider 102. , 107 come into contact with the magnetic disk 100 from the sharp edges,
There is a possibility that the magnetic disk 100, the head slider 102 and the like may be significantly damaged.

In the HDD, if the magnetic disk 100 is damaged, it becomes difficult to record or reproduce a signal on the damaged signal recording surface. Furthermore, if the damaged portion is large, the head slider 102 will be damaged when the head slider 102 passes over the damaged signal recording surface. If the head slider 102 is damaged, it will affect the flying of the head slider 102. In the worst case, the flying of the head slider 102 will be impossible and the HDD will fail.

Therefore, the present invention has been proposed in view of such a conventional situation, and prevents a disk-shaped recording medium or the like from being damaged by contact between a head slider and the disk-shaped recording medium. It is an object of the present invention to provide a head slider that has been provided, and a disk drive device that has improved portability by including such a head slider.

[0012]

A head slider according to the present invention that achieves the above object has a rail formed so as to protrude on a surface facing a disk-shaped recording medium, and a corner portion located outside the rail. And a projection having a height or less.

As described above, in the head slider according to the present invention, since the protrusion is formed at the corner portion located outside the rail, when the head slider comes into contact with the disk-shaped recording medium, the protrusion is formed from the disk. Will come into contact with the shape recording medium. Therefore, with this head slider, the contact pressure on the disk-shaped recording medium can be reduced, and damage to the disk-shaped recording medium and the like can be prevented. Further, in this head slider, since the height of the protrusion is equal to or less than the height of the rail, it is possible to prevent the protrusion from affecting the flying of the head slider.

According to another aspect of the present invention, there is provided a disk drive device comprising: a disk-shaped recording medium; a rail protruding from a surface facing the disk-shaped recording medium; and a corner portion located outside the rail. A head slider having a protruding portion having a height equal to or less than the height of the rail.

As described above, in the disk drive device according to the present invention, since the protrusion is formed at the corner located outside the rail of the head slider, the head slider comes into contact with the disk-shaped recording medium. At this time, the projection of the head slider comes into contact with the disk-shaped recording medium. Therefore, in this disk drive device, the contact pressure of the head slider against the disk-shaped recording medium can be reduced, and damage to the disk-shaped recording medium and the like can be prevented. Further, in this disk drive device, since the height of the protrusion of the head slider is equal to or less than the height of the rail, it is possible to prevent the protrusion from affecting the flying of the head slider. Therefore, in this disk drive device, it is possible to appropriately record and / or reproduce signals on the disk-shaped recording medium.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. As an embodiment of the present invention, a hard disk drive shown in FIG.
It is called D. 1) mounted inside a housing 2 are a magnetic disk 3 that is driven to rotate at a constant angular velocity by a spindle motor (not shown) and a magnetic head that records or reproduces information signals on or from the magnetic disk 3. A head actuator 4 having a head slider at the tip.

The head actuator 4 includes an arm 6 that rotates about a support shaft 5, a voice coil motor 7 provided on one side of the arm 6, and a predetermined arm attached to the other side of the arm 6. The suspension 8 has an elastic suspension 8 and a head slider 9 attached to the tip of the suspension 8.

The voice coil motor 7 includes a coil 10 attached to the arm 6 and a magnet at a position facing the coil 10 (the magnet is not shown by the cover 11 here). In the voice coil motor 7, a magnetic field is generated by supplying an electric current to the coil 10, and the arm 6 is rotated by a predetermined angle about the support shaft 5 by a magnetic action between the coil 10 and a magnet facing the coil 10. The magnetic disk 3 is rotated in the radial direction.

The head slider 9 is attached to the tip of the suspension 8 and urges the head slider 9 toward the magnetic disk 3 by elastic force.

As shown in FIGS. 2 and 3, the head slider 9 is made of, for example, AlTiC (Al
It is made of a non-magnetic member such as (2O3-TiC). In order to perform recording or reproduction on the head slider 9 while flying above the signal recording surface of the magnetic disk 3, a first rail is provided on the surface facing the magnetic disk 3 in a direction substantially parallel to the running direction of the magnetic disk 3. 12 and the second rail 13 are formed so as to protrude. That is, by forming the negative pressure generating groove 14 on the surface of the head slider 9 facing the magnetic disk 3, the head slider 9 is positioned slightly closer to the center than both ends of the head slider 9, and the running of the magnetic disk 3 is performed. A first rail 12 and a second rail 13 substantially parallel to the direction are formed to protrude.

The first rail 12 and the second rail 13 have tapered portions 12a, 13a at the inflow side ends of the air flow generated on the rotating magnetic disk 3 and flowing in the direction of arrow X.
Are formed respectively. A magnetic head 20 is attached to one of the first rail 12 and the second rail 13 at an outflow side end of the airflow flowing in the arrow X direction.

The head slider 9 has a corner located outside the first rail 12 and the second rail 13, that is, the first rail 12 and the second rail 12 of the head slider 9 having a substantially rectangular shape. Substantially protruding pads 15 are formed at four corners located outside the rail 13.

The pad 15 is formed integrally with the head slider 9 by etching or the like. Further, the pad 15 is equal to or less than the height of the first and second rails 12 and 13,
That is, the first and second rails 12 and 13 are formed at substantially the same height or lower than the first and second rails 12 and 13, and are substantially parallel to the magnetic disk 3. The cross section in each direction is substantially circular. Further, as shown in FIG. 4, the tip 15a of the pad 15 is chamfered by cutting off the edge of the upper surface.

In the HDD 1 configured as described above, the head slider 9 on which the magnetic head 20 is mounted is mounted on the signal recording surface of the magnetic disk 3 in order to avoid abrasion damage caused by contact between the magnetic disk 3 and the magnetic head 20. While slightly floating above, the magnetic head 20 performs signal recording and / or reproduction in a non-contact state. That is, the head slider 9
As shown in FIG. 5, the first rail 12 and the second rail 13 receive a levitation force (pressure) by an airflow in the direction of arrow X generated when the magnetic disk 3 is rotationally driven,
The floating force causes the magnetic disk 3 to fly from the signal recording surface at a small interval t. In FIG. 5,
The trajectory of the head slider 9 flying above the signal recording surface of the magnetic disk 3 is indicated by a broken line. The interval t
Is about 0.04 μm, and at the research level, it has been realized that this interval t is reduced to about 0.02 μm.

Thus, in the HDD 1, the magnetic head 20 mounted on the head slider 9 is
Can be prevented from being worn due to contact with.
Further, in the HDD 1, the head slider 9 can follow the irregularities on the surface of the magnetic disk 3 to some extent, and the spacing loss can be reduced.

Here, in the HDD 1, when the magnetic disk 3 rotates at a high speed and the head slider 9 comes into contact with the magnetic disk 3 or the like, if the magnetic head 20 mounted on the head slider 9 There is a possibility that the magnetic disk 3 or the like may be seriously damaged.

Therefore, in the HDD 1, as described above, the corners located outside the first rail 12 and the second rail 13 of the head slider 9, ie, the first part of the head slider 9 having a substantially rectangular shape. Substantially protruding pads 15 are formed at four corners located outside the second rail 13 and the second rail 13, respectively.

In this case, in the HDD 1, as shown in FIGS. 6 and 7, when the head slider 9 jumps and comes into contact with the magnetic disk 3 due to vibration, impact, or the like, the sharp ends of both sides of the head slider 9 are sharpened. Not from the edge,
The pad 15 comes into contact with the magnetic disk 3. FIG. 7 is an enlarged side view of a main part of FIG.

Therefore, in the HDD 1, the contact pressure of the head slider 9 on the magnetic disk 3 can be reduced, and the head slider 9 and the magnetic disk 3 can be prevented from being damaged. Therefore, even when such an HDD 1 is used in a so-called portable computer such as a notebook personal computer or a handheld personal computer which is taken out and used outdoors, the reliability can be sufficiently ensured.

In the head slider 9, as described above, the pad 15 is formed by the first and second rails 12 and 13.
, That is, the first and second rails 12 and 13
And the height is lower than the height of the first and second rails 12 and 13.

As a result, it is possible to prevent the pad 15 from affecting the flying of the head slider 9. Here, the pad 15 is formed about 0.1 to 0.2 μm lower than the first and second rails 12 and 13.

In the head slider 9, the pad 15
The surface of the first and second rails 12 and 13 facing the magnetic disk 3 is
It is preferable that the projected area be 1/100 or less.

Thus, in the head slider 9, for example, the height of the pad 15 is adjusted to the first and second rails 12 and 13.
Even if the height is the same as above, the floating force of the pad 15 has no effect. That is, the floating force of the pad 15 is 1/100 or less of the total floating force of the head slider 9, and can be ignored sufficiently. Therefore, it is possible to prevent the flying of the head slider 9 from being affected, and the first and second rails 12, 1 can be prevented.
3 can be prevented from interfering with the design.

As shown in FIGS. 8 and 9, the distance between the pad 15 and the end of the head slider 9 is s _1, and the maximum contact angle of the pad 15 with the magnetic disk 3 is θ.
In this case, the height h of the pad 15 is preferably equal to or more than s ₁ / tan θ.

Thus, in the HDD 1, when the head slider 9 jumps and comes into contact with the magnetic disk 3 due to vibration, shock, or the like, the head slider 9 can be reliably brought into contact with the magnetic disk 3 from the pad 15. .

When the distance between the pad 15 and the corner of the head slider 9 is s ₂ and the maximum contact angle of the pad 15 with the magnetic disk 3 is θ, the pad 1
The height h of 5 is preferably s ₂ / tan θ or more.

Thus, in the HDD 1, when the head slider 9 jumps and comes into contact with the magnetic disk 3 due to vibration or impact, the head slider 9 can be reliably brought into contact with the magnetic disk 3 from the pad 15.

Further, the head slider 9 is not necessarily limited to the one in which the pad 15 having the above-mentioned substantially circular cross section is formed. For example, as shown in FIG. The pad 16 having a substantially circular cross section may be formed only at the portion where the pad 16 is formed.

Thus, the contact pressure of the head slider 9 against the magnetic disk 3 can be reduced, and the head slider 9 and the magnetic disk 3 can be prevented from being damaged.

In the head slider 9, FIG.
A pad 17 having a substantially spherical tip portion 17a as shown in FIG. 1 may be formed.

As a result, the contact pressure of the head slider 9 against the magnetic disk 3 can be reduced, and the head slider 9 and the magnetic disk 3 can be prevented from being damaged.

The shape of the head slider 9 is not necessarily limited to the shapes of the first rail 12 and the second rail 13 which are substantially parallel to each other.

For example, another configuration example of the head slider to which the present invention is applied is shown in FIGS.

The head slider 30 is made of a non-magnetic material such as AlTiC (Al2O3-TiC) formed in a substantially rectangular shape, similarly to the head slider 9 described above. In order to perform recording or reproduction on the head slider 30 while flying above the signal recording surface of the magnetic disk 3, a negative pressure generating groove 31 having a predetermined shape is formed on the surface facing the magnetic disk 3. Thereby, the rail portion 32 is formed to protrude.

The rail portion 32 has a center rail portion 32a formed so as to draw an arc toward the inflow side end of the airflow flowing in the direction of arrow X generated by the rotation of the magnetic disk 3, and the center rail portion 32a. A pair of side rails 32b extending from both sides of the air rail 32a toward the outflow side end of the air flow, and an air flow from the center of the center rail 32a between the pair of side rails 32b. And a back rail portion 32c extending toward the outflow side end.

Further, a step surface 33 having a predetermined width is formed along the outer periphery of the rail portion 32, so that a step portion 34 one step lower than the main surface of the rail portion 32 is formed. The rail portion 32 is formed so as to surround the periphery thereof with a predetermined width.

An arrow X is attached to the back rail 32c.
A magnetic head 35 is attached to the outflow end of the airflow flowing in the direction.

The head slider 30 has substantially protruding pads 36 at both corners on the air inflow side located outside the rail 32.

The pad 36 is formed integrally with the head slider 30 by etching or the like, similarly to the pad 15 described above. The pad 36 is connected to the rail 32
, That is, the same height as the height of the rail portion 32 or a height lower than the height of the rail portion 32, and the cross section in a direction substantially parallel to the magnetic disk 3 has a substantially circular shape. Have been. The tip of the pad 36 is chamfered by cutting off the edge of the upper surface, similarly to the pad 15 described above.

The head slider 3 configured as described above
In the case of 0, since the pad 36 is formed in the corner portion located outside the rail portion 32, the same effect as the pad 15 formed on the head slider 9 described above can be obtained.

That is, such a head slider 30
When the head slider 30 jumps due to vibration or impact and comes into contact with the magnetic disk 3, the HDD 1 does not move from the sharp edges at both side ends of the head slider 30 but from the pad 36 described above to the magnetic disk 3. Will come into contact.

Therefore, in the HDD 1, the contact pressure of the head slider 30 against the magnetic disk 3 can be reduced, and the head slider 30 and the magnetic disk 3 can be prevented from being damaged. Therefore, even if such an HDD 1 is used in a so-called portable computer such as a notebook computer or a handheld personal computer which is taken out and used outdoors, the reliability can be sufficiently ensured.

In the head slider 30, as shown in FIG. 14, the height of the pad 36 is equal to or less than the height of the rail portion 32, that is, the height of the pad 36 is substantially the same as the height of the rail portion 32 or lower than the height of the rail portion 32. Is formed.

Thus, it is possible to prevent the pad 36 from affecting the flying of the head slider 30. Here, the pad 36 is formed lower than the rail portion 32 by about 0.1 to 0.2 μm.

The conditions such as the shape, height, position, and projected area of the pad 36 formed on the head slider 30 depend on the pad 15 formed on the head slider 9 described above.
Therefore, the description is omitted below.

The head slider 30 is not necessarily limited to the pad 36 having the above-mentioned substantially circular cross section. For example, the head slider 30 is provided on both sides of the air inlet side located outside the rail portion 32. A substantially protruding pad 37 as shown in FIGS. 15 and 16 may be formed in the corner portion.

The pad 37 is formed integrally with the head slider 30 by etching or the like, similarly to the pad 15 described above. The pad 37 is formed so as to stand up along the side surface of the corner portion, and its cross section in a direction substantially parallel to the magnetic disk 3 has a substantially circular shape at least at a portion facing the side surface of the corner portion. Have been. The pad 37 is chamfered so as to be more rounded toward the tip.

Thus, the contact pressure of the head slider 30 against the magnetic disk 3 can be reduced, and the head slider 30 and the magnetic disk 3 can be prevented from being damaged.

In the head slider 30, as shown in FIG. 17, the pad 37 has a height equal to or less than the height of the rail portion 32, that is, the pad 37 has a height substantially equal to or higher than the height of the rail portion 32. Is also formed at a low height.

Thus, it is possible to prevent the pad 37 from affecting the flying of the head slider 30. Here, the pad 37 is formed at substantially the same height as the rail portion 32.

The conditions such as the shape, height, position, and projected area of the pad 37 formed on the head slider 30 depend on the pad 15 formed on the head slider 9 described above.
Therefore, the description is omitted below.

In the head slider 30 described above,
The above-mentioned pads 36 and 3 are provided only at both corners on the air inflow side located outside the rail portion 32 where the distance between the end portion of the head slider 30 and the rail portion 32 is relatively large.
7 is formed, but the head slider 3
The pads 36 and 37 described above may be formed at both corners on the air outflow side located outside the rail 32 corresponding to the distance between the end of the air outflow side and the rail 32. .

The present invention is not limited to a magnetic disk drive in which a magnetic head is mounted on a head slider such as the HDD 1 described above, but is also applicable to an optical disk drive in which an optical head is mounted on a head slider. .
Further, such a magnetic disk device is not limited to the portable computer described above, and may be mounted on a portable electronic device such as a video camera, or the present invention may be applied to a stationary magnetic disk device or the like. It is.

[0064]

As described above in detail, according to the present invention, since the protrusion is formed at the corner located outside the rail of the head slider, the head slider and the disk-shaped recording medium are separated. When contact is made, the protrusion comes into contact with the disk-shaped recording medium. For this reason, the contact pressure of the head slider against the disk-shaped recording medium can be reduced, and damage to the disk-shaped recording medium can be prevented. In addition, since the height of the protrusion of the head slider is equal to or less than the height of the rail, it is possible to prevent the flying of the head slider from being affected. Therefore, in a disk drive device equipped with such a head slider, a notebook personal computer or a handheld personal computer to be taken out and used outdoors,
Even when used in a so-called portable computer, the reliability can be sufficiently ensured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration example of an HDD shown as an embodiment of the present invention.

FIG. 2 is a perspective view showing one configuration example of a head slider to which the present invention is applied.

FIG. 3 is a plan view showing a configuration of the head slider.

FIG. 4 is a perspective view showing a configuration of a pad formed on the head slider.

FIG. 5 is a schematic side view showing a state where the head slider flies above a signal recording surface of a magnetic disk.

FIG. 6 is a schematic side view showing a state where the head slider is in contact with a magnetic disk.

FIG. 7 is an enlarged side view of a main part of FIG.

FIG. 8 is a main part side view showing a contact state between the head slider and the magnetic disk.

FIG. 9 is a main part plan view showing the vicinity of a corner portion of the head slider.

FIG. 10 is a plan view showing another configuration example of the pad formed on the head slider.

FIG. 11 is a perspective view showing another example of the configuration of the pad formed on the head slider.

FIG. 12 is a perspective view showing another configuration example of the head slider to which the present invention is applied.

FIG. 13 is a plan view showing a configuration of the head slider.

FIG. 14 is a side view of a main part showing the vicinity of a corner part of the head slider.

FIG. 15 is a perspective view showing another example of the configuration of the pad formed on the head slider.

FIG. 16 is a plan view showing another example of the configuration of the pad formed on the head slider.

FIG. 17 is a side view of a main part showing the vicinity of a corner of the head slider.

FIG. 18 is a schematic perspective view showing the configuration of a conventional HDD.

FIG. 19 is a perspective view showing a configuration of a conventional head slider.

20A and 20B are schematic side views illustrating a process in which the head slider comes into contact with a magnetic disk, wherein FIG. 20A illustrates a state in which the head slider is separated from a signal recording surface of the magnetic disk, and FIG. FIG. 3C shows a state in which the slider approaches the signal recording surface of the magnetic disk, and FIG. 3C shows a state in which the head slider contacts the signal recording surface of the magnetic disk.

FIG. 21 is an enlarged side view showing a state where the head slider is in contact with a signal recording surface of a magnetic disk;

[Explanation of symbols]

1 HDD, 3 magnetic disk, 9 head slider,
12 first rail, 13 second rail, 15, 1
6, 17 pads, 20 magnetic heads, 30 head sliders, 32 rails, 36, 37 pads

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriyuki Mori 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F-term (reference) 5D042 NA02 PA01 PA05 QA02 QA03

Claims (21)

[Claims] 1. A rail protrudingly formed on a surface facing a disk-shaped recording medium, and a protruding portion having a height equal to or less than the height of the rail at a corner located outside the rail. Head slider. Wherein the distance between the end portion of the projection and the head slider and s _1, when the maximum value of the contact angle with respect to the disc-shaped recording medium of the protruding portions and theta, the height of the protrusions , S ₁ / tan θ or more. Wherein the distance between the corner portion of the projection and the head slider and s _2, when the maximum value of the contact angle with respect to the disc-shaped recording medium of the protruding portions and theta, the height of the protrusions , S ₂ / tan θ or more. 4. A projection area of the rail facing the disk-shaped recording medium with respect to a surface of the rail facing the disk-shaped recording medium is 1/100 or less. The head slider according to claim 1, wherein 5. The head slider according to claim 1, wherein the projection has a substantially circular cross section in a direction parallel to the disk-shaped recording medium. 6. The head slider according to claim 1, wherein the protrusion has a substantially circular cross section in a direction parallel to the disk-shaped recording medium only at a portion facing a side surface of the corner. 7. The head slider according to claim 1, wherein the tip of the projection is chamfered. 8. The head slider according to claim 1, wherein the tip of the projection has a substantially spherical shape. 9. The head slider according to claim 1, wherein the projection is formed so as to stand along a side surface of the corner. 10. The head slider according to claim 1, wherein a head for recording and / or reproducing a signal on and from the disk-shaped recording medium is provided at an end of the rail. 11. A disk-shaped recording medium, a rail protruding from a surface opposed to the disk-shaped recording medium, and a projection having a height equal to or less than the height of the rail at a corner located outside the rail. And a head slider having the same. 12. The distance between the protruding portion and the end portion of the head slider and s _1, when the maximum value of the contact angle with respect to the disc-shaped recording medium of the protruding portions and theta, the height of the protruding portions 12. The disk drive device according to claim 11, wherein is equal to or more than s ₁ / tan θ. 13. The head slider and the head slider
Distance to the corner _TwoAnd the disk of the projection
When the maximum value of the contact angle with respect to the recording medium is θ, the height of the protrusion is s_Two/ Tanθ or more
The disk drive device according to claim 11, wherein 14. A projection area of the rail facing the disk-shaped recording medium with respect to a surface of the rail facing the disk-shaped recording medium is 1/100 or less. 12. The disk drive device according to claim 11, wherein: 15. The disk drive device according to claim 11, wherein the projection has a substantially circular cross section in a direction parallel to the disk-shaped recording medium. 16. The disk drive device according to claim 11, wherein a cross section of the protrusion in a direction parallel to the disk-shaped recording medium is substantially circular only in a portion facing a side surface of the corner. . 17. The disk drive device according to claim 11, wherein a tip of said projection is chamfered. 18. The disk drive device according to claim 11, wherein the protrusion has a substantially spherical tip. 19. The disk drive device according to claim 11, wherein the protrusion is formed so as to stand along a side surface of the corner. 20. The disk drive device according to claim 11, wherein a head for recording and / or reproducing a signal with respect to the disk-shaped recording medium is provided at an end of the rail. 21. The disk drive according to claim 11, wherein the disk drive is portable.