JPH03159555A - Media driving gear - Google Patents

Abstract

PURPOSE:To improve the characteristic of motor structure with a warp of media due to thermal expansion prevented by forming the peripheral wall part of a hub of magnetic material and a contact location of the media of same material as a base plate. CONSTITUTION:When a media supporting flange part 15 is formed of same material as a base plate of a magnetic disk 17 which is piled together while being brought into contact with an upper surface of this flange part 15, these flange part and magnetic disk are equally thermally expanded. Consequently, the media supporting flange part 15 is prevented from disturbing expansion in a central part of the magnetic disk 17, brought into contact with this flange part 15, in a lower surface of this disk 17. Accordingly, the magnetic disk 17 in the lowermost side is prevented from generating a warp due to thermal expansion of the disk 17. While when a peripheral wall part 14 of a hub 12 is formed of magnetic material, a back yoke can be omitted, and the external diameter A of a stator 4 can be made large correspondingly, and thereby the characteristic of motor structure for rotating the hub 12 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to media drives, such as hard disk drives.

[Prior Art] A hard disk drive has a hub that houses a stator therein. A ring-shaped rotor magnet surrounding the stator is attached to the inner circumferential surface of the cylindrical peripheral wall of the hub, and at least one magnetic disk is attached to the outer circumferential surface. One magnetic disk is supported by being overlapped by a media support flange protruding from the outer peripheral surface of the peripheral wall.

By the way, the following two types of configurations around a hub in a conventional hard disk drive device are known.

One is that the peripheral wall of the hub and the media support flange are integrally molded and made of a magnetic material such as a ferrous material, and the rotor magnet is directly attached to the inner surface of the peripheral wall. be.

In addition, the other one is that the peripheral wall of the hub and the media support flange are integrally molded, and are made of aluminum alloy, and the rotor magnet is attached to the inner peripheral surface of the peripheral wall through a ring-shaped back yoke. This is the configuration with the .

[Problems to be Solved by the Invention] According to the former configuration around the hub, the magnetic disk is supported in direct contact with the media support flange portion made of an iron-based magnetic material. By the way, since the substrate of the magnetic disk is usually made of aluminum alloy or glass, the thermal expansion skewers of this substrate and the media support flange made of iron-based magnetic material form holes in each other.

Due to this difference in coefficient of thermal expansion, the media support flange portion prevents the expansion of the central portion of the magnetic disk in contact with the media support flange portion on one side of the magnetic disk. Therefore, there is a problem in that the magnetic disk is likely to warp.

In addition, according to the latter configuration around the hub, the media support flange portion and the magnetic disk substrate are made of the same material, so there is no problem like the former, but instead, the hub protrusion Requires a back yoke. Therefore,
If the dimensions of the peripheral wall of the knob remain the same, the outer diameter of the stator will be reduced by the thickness of the back yoke.

Therefore, as the size of the stator becomes smaller, the space for winding the stator also decreases, resulting in a problem that the characteristics of the motor structure for rotating the nozzle deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a media drive device that can prevent warping of media due to thermal expansion and improve the characteristics of a motor assembly that rotates a hub.

[Means for Solving the Problems] The present invention has a cylindrical peripheral wall portion that houses a stator therein, and a rotor magnet surrounding the stator is attached to the inner peripheral surface of the peripheral wall portion. It is applied to a media drive device that has a media support flange protruding from the outer circumferential surface of the media, and a knob on which a disk-shaped media is attached.

In order to achieve the above object, the present invention includes forming a peripheral wall of the hub from a magnetic material, and at least a media contacting portion of the media support flange on which the media is stacked, forming a substrate for the media. It is made of the same material as the material.

[Function] According to the configuration of the present invention, at least the media contact portion of the media support flange portion and the substrate of the media are made of the same material, so that the expansion of the central portion of the media that is in contact with the media support flange portion is prevented. , does not interfere with this aspect of the media. Since the peripheral wall of the hub having the media support section configured as described above on the outer peripheral surface is made of a magnetic material, this peripheral wall can be used as a back yoke for the rotor magnet that is directly attached to the inner peripheral surface. Available. Therefore, the back yoke, which was conventionally indispensable to prevent warping of the media, can be omitted, and the outer diameter of the stator can be increased accordingly.

[Example of Length] Hereinafter, a first embodiment of the present invention will be described with reference to FIG.

Reference numeral 1 in FIG. 1 denotes a motor housing made of iron-based material or aluminum alloy, and a stator mounting portion 2 is provided in the center of the motor housing, which projects toward the inner surface of the center portion of the end wall portion of the hub, which will be described later. A motor housing 1 is connected to a device frame (not shown) of a hard disk drive, and a flexible printed wiring board 3 provided with a necessary wiring pattern is attached to the housing 1.

The stator mounting portion 2 is formed into a cylindrical shape from the same type of batter as the motor housing 1. In addition, in the case of this example,
Although the stator mounting portion 2 has a certain shape attached separately from the motor housing 1, the stator mounting portion 2 may be formed integrally with the motor housing 1.

A stator 4 is fitted and attached to the outer peripheral surface of the stator attachment portion 2 . The stator 4 is formed from a stator core having a plurality of salient poles arranged radially, and a winding wound around each salient pole. Note that the lead wire connected to the terminal of the winding is connected to the wiring board 3.

A pair of bearings 5 are housed at both upper and lower ends of the stator mounting portion 2, and a rotating shaft 6 provided through the stator mounting portion 2 is supported by the rotating shaft 7E via these bearings 5. The rotating shaft 6 is made of the same material as the motor housing 1.

In the case of this large embodiment, the bearing 5 includes a bearing sleeve 5a fixed to the inner circumferential surface of the stator mounting portion 2 with adhesive, and a large number of bearing sleeves 5a provided between this inner surface and the ball bearing 7 of the rotating shaft 6. It is formed from a rotatable bearing ball 5b. The ball receiving groove 7 is formed in an annular shape around the rotating shaft 6 along the circumferential direction.

Note that 8' in FIG. 1 indicates the bearing sleeve 5a of the pair of bearings 5.
A coil spring is interposed therebetween, and is provided to apply preload to the pair of bearings 5 by its spring force. Further, numeral 9 in FIG. 1 is a fixed plate-shaped thrust bearing that is connected to the motor housing 1, and is provided to support a steel ball 10 that is fixed to the lower end of the rotating shaft 6. Furthermore, 1 in Figure 1
Reference numeral 1 denotes a magnetic fluid seal installed at the upper end of the stator mounting portion 2. This sealing action prevents dust from entering the magnetic disk (that is, disk-shaped media) side, which will be described later, through the stator mounting portion 2. It is designed to prevent

A hub 12 is attached to the upper end of the rotating shaft 6. The hub 12 includes an end wall 13 connected to the upper end of the rotating member 6, a cylindrical peripheral wall 14 continuous to the periphery of the end wall 13, and a wall protruding from the outer surface of the peripheral wall 14. The media support flange portion 15 has a substantially hat shape with an open bottom surface.

The end wall portion 13 is positioned to face the upper surface of the stator 4, and the peripheral wall portion 14 is positioned to house the stator 4 therein. The end wall portion 13 and the peripheral wall portion 14 are integrally formed of a ferromagnetic material such as an iron-based material.

A cylindrical rotor magnet 16 surrounding the stator 4 is attached to the inner peripheral surface of the peripheral wall portion 14 .

The magnet 16 has a plurality of magnetic poles, and its inner peripheral surface and the tip end surface of the salient poles of the stator 4 are closely opposed to each other with a slight air gap.

It is provided protrudingly on the outer surface. The flange portion 15 has a ring shape and is molded separately from the peripheral wall portion 14, and is attached to the peripheral wall portion 14 by adhesion or press fitting. The media support flange portion 15 is made of the same material as the substrate of the magnetic disk, which will be described later.

At least one magnetic disk 17 is attached to the hub 12. FIG. 1 shows an example in which three magnetic disks 17 are fitted and attached to the outer surface of the peripheral wall portion 14. The magnetic disk 17 has a disk-shaped substrate with a central hole, and a magnetized recording layer is provided on the surface of the substrate, and the substrate is usually made of aluminum alloy. Therefore, the media support flange portion 1
5 is made of aluminum alloy in this embodiment.

The one placed at the bottom of the magnetic disks 17 is
The hole edge of the center hole is connected to the media support flange portion 15.
It is supported in the axial direction by this flange portion 15 so as to be superimposed on the upper surface of the flange portion 15 . A spacer ring 18 is supported between the vertically adjacent magnetic disks 17, and the uppermost magnetic disk 17 is held down by a disk holder screwed onto the top of the hub 12. The spacer ring 18 and the disc holder 19 are also made of the same type of aluminum alloy as the substrate.

In the magnetic disk drive device described above, since the media support flange portion 15 is formed of the same material as the substrate of the magnetic disk 17 which is stacked in contact with the upper surface of the media support flange portion 15, they undergo the same thermal expansion. Therefore, the magnetic disk 1 with which the media support flange portion 15 is in contact
The expansion of the Φ center portion of the disc 17 is not obstructed in the downward direction. Therefore, the lowermost magnetic disk 17 does not warp due to its thermal expansion. Of course, other magnetic disks 17 do not suffer from warping due to thermal expansion for the same reason.

Since the media support flange portion 15 and the other hub constituent parts, such as the end wall portion 13 and the peripheral wall portion 14, are molded separately, the peripheral wall portion 14 of the hub 12 can be formed of a magnetic material. Therefore, this peripheral wall portion 14 can be used as a back yoke for the rotor magnet 16 that is directly attached to the inner peripheral surface of the peripheral wall portion 14. Therefore, the back yoke can be omitted, and the outer diameter A of the stator 4 can be increased accordingly. In this way, a large space for wires in the stator 4 can be secured, and a large number of windings can be wound, so the hub 1
The characteristics of the motor structure that rotates the motors 2 and 2 simultaneously can be improved.

The second embodiment of the present invention shown in FIG. 2 differs from the first embodiment only in the structure of the media support flange portion 15, and the rest of the structure is the same as the first embodiment. , the same components are given the same reference numerals and their explanations will be omitted.

The media support flange portion 15 in this embodiment is formed from a base portion 15g and a media contact portion 15b. The base portion 15a is a ring-shaped protruding portion integrally formed on the outer surface of the peripheral wall portion 14 made of an iron-based material. The media contact portion 15b is made of the same material as the substrate of the magnetic disk 17, and the base portion 15a is made of the same material as the substrate of the magnetic disk 17.
It is molded in the same ring shape as the base part 15a, and is attached to the upper surface of the base part 15a. Of course,
On the upper surface of this media contacting portion 15b, the lowermost magnetic disk 17 is provided with the hole edge of its center hole overlapped.

Therefore, in this second embodiment as well, the intended purpose of the present invention can be achieved for the same reason as in the first embodiment.

[Effects of the Invention] According to the media drive device of the present invention described above, the peripheral wall portion of the hub to which the rotor magnet surrounding the stator is attached to the inner peripheral surface is formed of a magnetic material, and the peripheral wall portion of the hub is made of a magnetic material. At least the media contact portion of the media support flange protruding from the outer circumferential surface on which disk-shaped media is stacked is made of the same material as the substrate of the media, so that the media support flange can be attached to this portion. The expansion of the central part of the media that is in contact with it is no longer obstructed by one side of the media, which prevents the media from warping due to thermal expansion, and allows the peripheral wall to be used as a back yoke for the rotor magnet, eliminating the need for a back yoke that was previously required. By omitting this, the outer diameter of the stator can be increased, improving the characteristics of the motor structure that rotates the hub.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a second embodiment of the present invention. 4... Stator, 12... Hub, 14... Peripheral wall portion, 15... Media support flange portion, 15b... Media contact portion, 16... Rotor magnet.

Claims (1)

[Scope of Claims] It has a cylindrical peripheral wall portion that houses the stator therein, a rotor magnet surrounding the stator is attached to the inner peripheral surface of the peripheral wall portion, and a media support flange is attached to the outer peripheral surface of the peripheral wall portion. A hub having a protruding portion and a disk-shaped media mounted on the flange portion, wherein the peripheral wall portion of the hub is formed of a magnetic material, and at least the media of the media support flange portion is overlapped. A media drive device characterized in that a media contact portion is formed of the same material as the substrate of the media.