ROTOR HUB, MOTOR, AND DISK DRIVING DEVICE

Abstract

A rotor hub includes a shaft connecting portion arranged to be connected to a shaft serving as a central axis, a disk loading portion centered about the central axis and arranged to support a disk shaped storage medium mounted thereon, a yoke arranged below the disk loading portion and supporting a field magnet at one of an inner side surface thereof and an outer side surface thereof, and a flexible portion connecting the disk loading portion to the yoke and being flexible with respect to a force applied thereto from the yoke.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an internal configuration of a disk driving device according to a first preferred embodiment of the present invention.

FIG. 2 is a cross sectional view of a motor.

FIG. 3 is an enlarged cross sectional view of a portion of a rotor hub.

FIG. 4 is an enlarged cross sectional view of a rotor hub which is an exemplary comparison.

FIG. 5 is a graph indicating a relation between a degree of deformation of a disk provided in a comparative rotor hub and the temperature.

FIG. 6 is a diagram showing a variation of the degree of the deformation of the disk loading surface when the temperature of the rotor hub changes.

FIG. 7 is an enlarged cross sectional view of a portion of a rotor hub according to a second preferred embodiment of the present invention.

FIG. 8 is an enlarged cross sectional view of a portion of a rotor hub according to a third preferred embodiment of the present invention.

FIG. 9 is an enlarged cross sectional view of a portion of a rotor hub according to a fourth preferred embodiment of the present invention.

FIG. 10 is an enlarged cross sectional view of a portion of a rotor hub according to a fifth preferred embodiment of the present invention.

FIG. 11 is an enlarged cross sectional view of a portion of a rotor hub according to a sixth preferred embodiment of the present invention.

FIG. 12 is an enlarged cross sectional view of a portion of a rotor hub according to a seventh preferred embodiment of the present invention.

FIG. 13 is an enlarged cross sectional view of a portion of a rotor hub according to an eighth preferred embodiment of the present invention.

Claims

1. A rotor hub for use in a motor of a disk drive, comprising: a shaft connecting portion arranged to be connected to a shaft serving as a central axis;a disk loading portion centered about the central axis, arranged radially outside the shaft connecting portion so as to surround the central axis, and arranged to support a disk-shaped storage medium loaded thereon;a hollow, approximately cylindrical yoke arranged below the disk loading portion, centered about the central axis, and supporting a field magnet at one of an inner side surface thereof and an outer side surface thereof; anda flexible portion connecting the disk loading portion to the yoke and arranged to absorb a force applied thereto from the yoke.

2. The rotor hub according to claim 1, wherein the disk loading portion has a coefficient of thermal expansion greater than a coefficient of thermal expansion of the yoke.

3. The rotor hub according to claim 1, wherein the flexible portion has a hollow, approximately cylindrical shape centered about the central axis; anda radial width of the flexible portion is smaller than a radial width of the disk loading portion.

4. The rotor hub according to claim 3, wherein the disk loading portion has an upper surface arranged to receive the disk-shaped storage medium thereon and a lower surface including a concave portion, the concave portion opening toward the lower surface and having an approximately annular shape centered about the central axis; anda radially outer surface of the concave portion is a radially inner surface of the flexible portion.

5. The rotor hub according to claim 4, wherein the concave portion is defined by the radially outer surface which is substantially parallel to the central axis and an inclined surface connected at an upper end thereof to the radially outer surface, the inclined surface being inclined to the central axis such that the upper end thereof is farther from the central axis than a lower end thereof.

6. The rotor hub according to claim 5, wherein a maximum radial width of the concave portion is equal to or shorter than about half of a total of a depth of the concave portion in an axial direction along the central axis plus a depth of the disk loading portion in the axial direction.

7. The rotor hub according to claim 3, wherein the radial width of the flexible portion is equal to or shorter than about half of the radial width of the disk loading portion.

8. The rotor hub according to claim 3, wherein a minimum depth of the disk loading portion in the axial direction is equal to or greater than about 30% of a depth between an upper surface of the disk loading portion and an upper end of the yoke in the axial direction.

9. The rotor hub according to claim 1, wherein the flexible portion includes a recess on its radially outer side surface, the recess being concave radially inward and having an annular shape centered about the central axis.

10. The rotor hub according to claim 9, wherein a radially innermost portion of the recess of the flexible portion is arranged radially inside a radially outer end of the disk loading portion.

11. The rotor hub according to claim 1, wherein the flexible portion has a smaller Young's modulus than the disk loading portion.

12. The rotor hub according to claim 11, wherein the disk loading portion is made of metal and the flexible portion is made of resin or plastic.

13. A motor for use in a disk drive for rotating a disk-shaped storage medium, comprising: a rotor including the rotor hub according to claim 1 arranged such that a central axis of the rotor hub is coincident with a rotation axis of the motor, and the field magnet affixed to the yoke of the rotor hub and arranged around the rotation axis;a stator including an armature generating together with the field magnet a torque centered about the rotation axis, and a base portion to which the armature is attached; anda bearing supporting the rotor in a rotatable manner around the rotation axis relative to the stator.

14. A disk drive comprising: a disk-shaped storage medium capable of storing information;the motor according to claim 13 for rotating the disk-shaped storage medium;a head arranged to at least one of read information from and write information to the disk-shaped storage medium; anda head moving arrangement arranged to move the head relative to the disk-shaped storage medium and the motor.

15. The rotor hub according to claim 1, wherein the yoke is made of a magnetic material.