JPH0718055Y2 - Spindle motor for disk - Google Patents

Description

The present invention relates to a disk spindle motor for rotationally driving a magnetic disk.

[Prior Art and Problems Thereof] So-called "thermal off-track" has conventionally been regarded as a problem in this type of motor. That is, when the bracket of the spindle motor thermally expands, the gap between the bearing and the bracket caused by the difference in the coefficient of thermal expansion may cause the rotating shaft to tilt toward the magnetic head. Due to the presence of the notch and the thick portion, uneven strain is generated, which causes the tilting of the rotation axis of the magnetic disk. When the rotation axis falls, a malfunction occurs in writing / reading information by the magnetic head with respect to the track on the magnetic head.

As a conventional measure, the rotating shaft and the magnetic head must be 90 ° against the tilt due to the gap between the bracket and the bearing.
A method of providing a leaf spring or an O-ring in an eccentric manner in order to press in the direction of has been considered.

However, the conventional measures are not sufficient in terms of correcting the distortion of the flange portion of the bracket.

It is an object of the present invention to provide a disk spindle motor capable of stable writing and reading with respect to temperature changes.

[Means for Solving the Problems] The present invention includes an elastic plate member 19 fixed to the flange portion 3 of the bracket 4 in a laminated manner, and the center of the magnetic head 14 for the disk 11 and the axis of the rotary shaft 7. The disk in the direction orthogonal to the straight line L connecting with and when viewed from the axis of the rotary shaft 7.
The strain correction portion 27 such as the notch groove 26, the small curved portion 28, the concave groove 29, and the bent portion 30 for tilting the rotary shaft 7 outward in the radial direction of 11 is provided outside the elastic plate material 19. At least one end 25 was attached.

[Operation] During thermal expansion of the bracket, internal stress is locally generated in the bracket due to non-uniformity in shape, wall thickness, etc., and other causes. That is, due to the presence of notches or thick portions of the flange portion, uneven distortion will occur in a part of the flange portion, but the metal plate provided with the distortion correction portion is the flange portion of this bracket. On the other hand, the strain is converted to a harmless circumferential position-that is, a circumferential position where off-track does not occur even if the magnetic disk is tilted-to concentrate and absorb the strain.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 3, reference numeral 1 denotes a disk spindle motor according to the present invention, which includes a bracket 4 made of a non-magnetic material such as aluminum, and the bracket 4 is provided outside the bearing support boss portion 2 It integrally has a flange-shaped flange portion 3. The rotating shaft 7 is rotatably supported by the boss portion 2 via bearings 5 and 6. The rotor holder 8 is fixed to one end of the rotary shaft 7 and rotates integrally, but the rotor magnet 15 is fixed to the inner peripheral surface of the rotor shaft 8 so as to surround the stator 10 and the coil 9.
Correspond.

Reference numeral 11 denotes a magnetic disk, which is attached to the hub 12. The hub 12 is fixed to the other end of the rotating shaft 7 and rotates integrally.

Reference numeral 13 is an access arm, and 14 is a magnetic head provided at the tip of the access arm 13 for writing / reading information to / from the magnetic disks 11. The magnetic head 14 moves back and forth in the directions indicated by arrows A and B.

Then, on the back surface 3b of the flange portion 3 of the bracket 4,
Metallic elastic plate material made of magnetic material for magnetic shield in a laminated form
19 is fixed with screws 24, etc.

In the illustrated example, the printed circuit board 23 and the elastic plate material 19 are bonded and integrated in advance, and the elastic plate material 19 is directly contacted with the back surface 3b side of the flange portion 3 and fixed in a laminated form. . Further, the flange portion 3 is attached to the device body 20 with screws 24, etc.

Then, FIG. 1 illustrates a specific shape of the elastic plate material 19. As is clear from this figure, a straight line L connecting the center of the magnetic head 14 for the disk 11 and the axis of the rotary shaft 7 is substantially formed. A notch groove 26 extending in the radial direction when viewed from the axial direction of the rotary shaft 7 is formed in the outer end portion 25 which is a direction orthogonal to each other, and serves as a distortion correction portion 27. That is, the notch groove 26 is formed by notching from the outer peripheral end in the inner diameter direction, but in the same figure, the case where it is provided at a position of 90 ° with respect to the corresponding position X of the magnetic head 14 is shown.
It is provided on a line orthogonal to the straight line L.

The magnetic head 14 moves back and forth along the straight line L as indicated by arrows A and B.

Generally, in the case where there is no distortion correcting portion 27 including the above-mentioned notch groove 26, as shown in FIG. 3, the bracket 4 or the like causes thermal distortion or the bearings 5 and 6 are accompanied by a temperature rise during motor rotation.
Due to the thermal change of the fitting intersection of the parts, the axis of the rotating shaft 7 falls down, and the magnetic disk 11 on the hub 12 inclines like a virtual line.

That is, when the distortion correction unit 27 is not provided, it is not known in which direction the rotary shaft 7 falls, but in this case, the case where the rotary shaft 7 falls to the magnetic head 14 side is shown. It is indicated by W ₀ . Therefore, the A and B direction components in this case are as large as H ₀ .

On the other hand, as described above, if the notch groove 26 is formed in the elastic plate member 19 as the distortion correction portion 27 as shown by the solid line in FIG.
The strength of the notch groove 26 and its vicinity becomes weaker than that of other portions. Therefore, the notch groove 26 and its vicinity are likely to be elastically deformed, and when thermal stress is generated due to thermal expansion, the thermal stress causes the notch groove 26 and its vicinity to be elastically deformed slightly (corresponding to the correspondence of the bracket 4). The part to be elastically deformed a little). That is, the distortion correction portion formed by the notch groove 26
Due to 27, the rotary shaft 7 does not fall to the side of the distortion correction unit 27, and does not fall to the side of the magnetic head 14. When the distortion correction unit 27 is not provided because the distortion correction unit 27 is not provided, the tilt direction and size are assumed to be the arrow W ₀ .
As indicated by the solid line in the figure, the direction and size are as shown by the dashed arrow W ₂ . Therefore, when the distortion correction unit 27 is provided in this way, the component of the arrow W _{2 in} the A and B directions is H _2, and the H ₀
It can be seen that it is significantly reduced.

That is, according to the present invention, the tilting in the A and B directions that is likely to cause off-track (hazardous) can be significantly reduced. At the same circumferential position as the notched groove 26 shown by the solid line, if the notched groove is made smaller as shown by the phantom line in FIG. 1, the falling direction will be W ₁ , but this will prevent off-track. Turns out to be inadequate. That is, by increasing the size of the cutout groove 26 in accordance with the original size W ₀ of the tilt, the position of the tilt can be moved to the substantially orthogonal position 25.

Therefore, the range of the outer end portion 25 is set to the range of the angle 2θ as shown in FIG. Specifically, the outer end portion 25 has a range of a predetermined angle θ (for example, 30 °) in the circumferential direction on both sides around a straight line substantially orthogonal to the straight line L. In general, the angle 2θ varies depending on the structure and material of the bracket 4, so that the present invention does not limit the presence of the notch groove 26 within the angle 2θ.

Then, if the notch groove 26 is displaced as shown by an imaginary line C in FIG. 1, the tilting direction becomes a straight line orthogonal to the straight line as shown by an arrow W ₃ , and is most harmless to off-track. It becomes a position.

Next, in FIG. 4 and FIG. 5 showing the VV cross section, the case where the strain correction portion 27 of the elastic plate material 19 is constituted by the small curved portion 28 in the radial direction is shown. Of course, in this case as well, it is desirable to dispose the small curved portion 28 at the outer end portion 25 that is substantially orthogonal to the straight line L (center angle 2θ is about 60 °) when viewed from the axial direction. It should be noted that, as described above, the present invention is also applicable to the case where the 2θ is further increased depending on the material and structure of the bracket 4.

In addition, as shown in FIG.
The radial concave groove 29 formed on one surface of the groove 19 may be used.

Thus, in another embodiment shown in FIG. 7, the circuit board 23 and the elastic plate member 19 are completely separate bodies and are fixed to the rear surface 3b of the flange portion 3 of the bracket 4 and the surface 3a. .
That is, the elastic plate member 19 has a flange front surface, contrary to FIG.
3a is fixed with screws 24, etc., and in this case, the distortion correction portion 27 formed on the elastic plate material 19 is compared with FIG. 1 and FIG.
The straight line L is provided at a symmetrical position.
The elastic plate material 19 is also a steel plate that also serves as a magnetic shield plate.

Next, FIGS. 8 and 9 show still another embodiment, in which a part of the circumference of the elastic plate material 19 in a free state is bent to form a bent portion 30 and abutted on the flange portion 3. Only by making the distorted part 30 float (jump up),
By forcibly tightening with a fastener such as 24 until it comes into contact with the flange portion 3, an elastic force such as a leaf spring is constantly applied to the flange portion 3, and the distortion correcting portion 27 is configured with this. To do. The circumferential position of the distorted portion 30 is the same as in the above-described embodiment.

Needless to say, the present invention can be applied to spindle motors other than the type, structure, and shape shown.

[Advantages of the Invention] The disk spindle motor according to the present invention is a disk
Since the rotary shaft 7 is set to fall outward in the radial direction substantially orthogonal to the straight line L connecting the center of the magnetic head 14 for 11 and the shaft center of the rotary shaft 7, the distortion correction unit 27 is set to the magnetic head 14. Since the rotary shaft 7 is attached in a circumferential direction substantially orthogonal to the corresponding position X in FIG.
It is possible to concentrate the tilt direction of the magnetic disk 11 in a harmless direction, and it is possible to effectively prevent a malfunction such as off-track from occurring with the temperature rise during motor rotation--so-called thermal off-track. .

[Brief description of drawings]

FIG. 1 is a simplified plan view for briefly explaining one embodiment of the present invention and for explaining the operation, FIG. 2 is a sectional front view, FIG. 3 is a sectional view for explaining the operation, and FIG. 4 is FIG. FIG. 5 is a cross-sectional view taken along line VV of FIG. 4, FIG. 6 is a cross-sectional view of a main portion of the modification, and FIG. 7 is a cross-sectional view of another embodiment. FIG. 9 is a sectional view of an essential part of another embodiment. 3 ... Flange part, 4 ... Bracket, 11 ... Magnetic disk,
14 ... Magnetic head, 19 ... Metal plate, 25 ... Outer end portion, 26 ... Notch groove, 27 ... Distortion correcting portion, 28 ... Small curved portion, 29 ... Recessed groove, 30 ... Lifting portion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-112263 (JP, A) JP 63-259867 (JP, A) Actual 60-60-14674 (JP, U) Actual 59- 180267 (JP, U) Actually open Sho-23-23782 (JP, U) Open technical report 83-7525

Claims (1)

[Scope of utility model registration request] 1. A direction orthogonal to a straight line L connecting a center of a magnetic head 14 for a disk 11 and an axis of a rotary shaft 7 with an elastic plate material 19 fixed to a flange portion 3 of a bracket 4 in a laminated manner. And the notch groove 26, the small curved portion 28, the concave groove 29, the distorted portion 30, etc. for tilting the rotating shaft 7 outward in the radial direction of the disk 11 when viewed from the axis of the rotating shaft 7. At least one distortion correcting section 27 is attached to the outer end 25 of the elastic plate member 19, and the spindle motor for a disk is characterized.