JPS62279560A - Disk driving device - Google Patents

Abstract

PURPOSE:To improve the precision of deflection of an output shaft by unbalancing the attraction between a rotor and a stator with respect to the output shaft of a motor to absorb play between the output shaft and a bearing and eliminating adhesion between an inner wheel and an outer wheel. CONSTITUTION:The output shaft 1 of an axial gap type direct driving motor is supported by one metal bearing 8 and one ball bearing 7. A stator 10 is so constituted that the air gap to a magnet 4 is different between the right and the left of the output shaft 1 and has a minimum value l1 and a maximum value l2, and this gap is smoothly changed. As the result, the partial attraction between the magnet 4 and the stator 10 is different, and a rotor 3 is moved around the ball bearing part of the output shaft 1 in the direction of an arrow 9, and the output shaft 1 is pressed to the left wall of the metal bearing 8. Unless the radial load applied to the output shaft 1 from the external exceeds the force which presses the output shaft 1 to the metal bearing 8, the output shaft 1 is held in a certain position.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a structure for preventing vibration of an output shaft of a direct drive motor that rotationally drives a disc-shaped recording medium.

[Conventional technology]

A conventional direct drive motor that rotationally drives a disk-shaped recording medium has a structure shown in FIGS. 4 and 5.
Both FIG. 11 and FIG. 5 are sectional views of a conventional direct drive motor. All of them show axial gap type direct drive motors.

A rotor holder 42 is fixed to the output shaft 41 , and a rotor 43 for generating rotational power is fixed to the rotor holder 42 .

Further, a magnet 44 is bonded to the rotor 43 and forms a magnetic circuit with the stator 50. By passing a current through the coil 46 disposed on the base Fi 45, rotational power is generated between the coil 46 and the magnet 44.

On the other hand, the output shaft 41 is supported by two ball bearings 47 in FIG. 4, and by one metal bearing 48 and a ball bearing 47 in FIG.

Furthermore, in FIG. 4, a preload spring 49 is provided to reduce the radial clearance of the ball bearing 47 on the upper side in the figure to zero.

[Problem that the invention seeks to solve]

However, in the prior art shown in FIG. 4 described above, the output shaft 4
1, two ball bearings 47 and a preload spring 49 are used to keep the runout of the ball bearing 47 small, and the clearance between the inner ring of the ball bearing 47 and the output shaft 41 must be maintained accurately. The mechanism alone accounts for about 1/3 of the cost of the entire motor, making it extremely expensive.

Furthermore, as shown in FIG. 5, if the output shaft 41 is supported by metal bearings for 4 days, it is advantageous in terms of cost. This was impossible, and unless the output shaft 41 was pressed to one side by a pinch roller, etc., it would swing within the clearance range with the metal bearing, and it could not meet the demands for high-precision shaft swing. .

Therefore, the present invention aims to solve these problems.
The objective is to provide a direct drive motor for driving a disc recording medium that is low cost, has a highly accurate output shaft with little runout, and has an output shaft with little vibration.

[Means for solving problems]

The disk drive device of the present invention includes: (1) an output shaft that rotationally drives a disk-shaped recording medium;
A direct drive motor with an integrated rotor for generating rotational power is installed, and the output shaft of the direct drive motor and the bearing are shifted to one side.
The apparatus is characterized in that the magnetic resistance between the rotor and the stator during one rotation of the rotor is changed as means for configuring the attraction force between the rotor and the stator to be unbalanced with respect to the output shaft.

(2) As a means for configuring the suction force between the rotor and the stator to be unbalanced, the air gap between the rotor and the stake during one revolution is configured to change smoothly.

(3) The furnace is characterized in that the furnace suction force applied to the output shaft by changing the magnetic resistance between the rotor I and the stator during its rotation is made larger than the force applied to the output shaft as a load from the outside.

[Effect]

According to the above configuration of the present invention, the magnetic resistance between the stator and the output shaft during one rotation of the rotor is unbalanced with respect to the output shaft. It tends to tilt due to the unbalance of the suction force with the stator relative to the output shaft.

Also, in the radial gap method, radial force is applied to the output shaft due to the unbalance of the rotor and stator suction forces, so it is necessary to always apply a radial force in the -force direction to each output shaft. I can do it,
Even if the output shaft is supported by a metal bearing with a large clearance, the runout of the output shaft can be kept to a minimum.

Note that the gradual change in magnetic resistance between the rotor and stator prevents the motor from becoming unevenly rotated due to sudden changes in the attractive force between the rotor and stator.

〔Example〕

FIG. 1 is a sectional view of an axial gear type direct drive motor of a disk drive device in one embodiment of the present invention. The output shaft 1 has a rotor holder 2
is fixed at the correct size, and the rotor 3 for generating rotational power
is fixed to the rotor holder 2. Furthermore, a magnet 4 is glued to the rotor 3, and a stator (1
) constitutes a magnetic circuit.

Further, a coil 6 is disposed on the substrate 5, and the magnet 4 is driven to rotate around the output shaft 1 by passing a current through the coil 6.

On the other hand, the output shaft 1 is supported by one metal shaft 8 and one ball bearing 7.

The stator (1) is configured so that the air gap with the magnet 4 is different between the cloth and the left side in the figure with respect to the output shaft 1, and is configured such that the air gap II is the smallest, the air gap 12 is the largest, and , this air gap change occurs gradually.

In a direct drive motor with such a configuration, the air gap 1. Since and 12 are different, the partial attraction forces between the magnet 4 and the stator (1) naturally differ. Therefore, the rotor 3 moves in the direction of arrow 9 in the figure around the ball bearing portion of the output shaft 1, and the output shaft 1 is pressed against the left wall of the metal bearing 8.

In this state, as long as the radial load applied to the output shaft 1 from the outside does not exceed the force that presses the output shaft 1 against the left wall of the metal bearing 8, the output shaft can maintain a constant position.

FIG. 2 is a sectional plan view of a radial gap type direct drive motor in another embodiment of the present invention.

A rotor 3 is configured to be rotatable around an output shaft 1, and a magnet 4 is bonded to the rotor 3. The stator (1) has a substantially circular outer periphery, and its center 25 is
It is located at a point moved by X from the center of the output shaft 1. A coil 6 is wound around the stator (1).
and the magnet 4 constitute a magnetic circuit.

In this configuration, since the stator (1) and the rotor 3 are eccentric, the air gap between the magnet 4 and the stator (1) changes smoothly from 1+ to 12. Therefore, the attraction force between the magnet 4 and the stator (1) for the total circumference is as follows with respect to the output shaft 1:
It acts in the direction of arrow 27 in the figure, and as in the embodiment of FIG. 1, it is possible to eliminate the clearance between the bearing and the output shaft.

FIG. 3 is a third embodiment of the present invention, and is a sectional view of an axial gear, bulb-type direct drive motor.

A rotor 3 provided on an output shaft 1 and a stator (1) provided opposite to each other are provided.

A magnet 4 is bonded to the rotor 3.

The stator (1) is provided with a convex portion (1)a to vary the air gap. The output shaft 1 is
In order to receive the attractive force of the magnet 4, it has a spherical end face, and forms a sliding bearing with the thrust receiver 35. - The radial bearing of the force output shaft l is constituted by a bearing metal 36.

According to the above configuration of the present invention, even if the bearing of the output shaft is completely composed of a sliding bearing, it is possible to realize a bearing structure with a high precision equivalent to or higher than that using a ball bearing bearing.

〔Effect of the invention〕

As described above, according to the present invention, by making the suction force between the rotor and stator unbalanced with respect to the output shaft, play between the output shaft and the bearing can be absorbed. The clearance between the hole diameter of the inner shaft and the shaft diameter can be canceled, and the selective fitting of the shaft and inner ring, which is carried out in motors such as VTRs, for example, can be abolished. Similarly, bonding between the inner ring and the shaft can also be eliminated.

With metal bearings, the bearing and shaft diameter can be roughly managed, reducing costs and absorbing backlash, which improves the runout accuracy of the output shaft.

Further, by making the change in magnetic resistance gentle, the deterioration of rotational axis unevenness can be reduced, and the present invention can be applied to equipment requiring high rotational accuracy, which is a very significant effect.

[Brief explanation of drawings]

FIGS. 1 and 3 are cross-sectional views of an asymmetrical gap type direct drive motor of the present invention. FIG. 2 is a sectional plan view of the radial gap type direct drive motor of the present invention. FIGS. 4 and 5 are cross-sectional views of conventional direct drive motors. 1... Output shaft 2... Rotor holder 3... Row 9- 4... Macnet 5...
・Substrate 6...Coil 7...Ball bearing 8...Metal shaft (1)...Stator
25...Stator center 35...Thrust receiver 36...Bearing metal salt Applicant Seiko Epson Corporation 3-0-Fu 3-Me? Ishinaka Yukei-
77゛刹2. (1)-Su〒-ku 5-Group 1st, 7 Figure 2 Figure 3 Figure 5

Claims (3)

[Claims] (1) In a disk drive device equipped with a direct drive motor that integrally includes an output shaft that rotationally drives a disc-shaped recording medium and a rotor that generates rotational power, the output shaft and bearing of the direct drive motor The magnetic resistance between the rotor and the stator changes during one rotation of the rotor as means for configuring the attraction force between the rotor and the stator to be unbalanced with respect to the output shaft so that the play in the rotor is shifted to one side. A disk drive device characterized by: (2) As a means for configuring the suction force between the rotor and the stator to be unbalanced, the air gap between the rotor and the stator during one rotation is configured to change smoothly. The disk drive device according to item 1. (3) The rotor attraction force applied to the output shaft by changing the magnetic resistance with the stator during one revolution of the rotor,
3. The disk drive device according to claim 1, wherein the disk drive device is configured to be larger than the force applied to the output shaft as a load from the outside.