JPH097291A - Spindle motor - Google Patents

Abstract

PURPOSE: To prevent the deviation and falling of a disk mounting surface by providing an output shaft part and a small diameter part on a shaft and abutting a part of a chucking magnet yoke on its step part. CONSTITUTION: A step surface 25 is formed between an output shaft part and a small diameter part on a shaft 30. A erected part 26 for engaging the small diameter part 24 is formed in the inner peripheral part of a chucking magnet yoke 21-1 forming a rotor yoke and the yoke 21-1 engages with the upper part of the small diameter part 24 of the shaft 30 in the erected part 26 through the step surface 25. The inner race of a first ball bearing 3-1 engaged with the inner peripheral part of a holder 16-1 is fixed on the small diameter part of the shaft on the lower side of the erected part 26 and the erected part 26 is held between the upper surface of the inner race 31 and the step surface 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor structure, and more particularly to a spindle motor formed by strengthening the fitting strength between a rotor yoke and a shaft.

[0002]

2. Description of the Related Art Information disks are called magneto-optical disks (MO;
There are information media configured as a magnetic optical disk (FD) and a flexible disk (FD; flexible disk). This kind of information media has a unified standard and is convenient for use. If the information disk is a magneto-optical disk, 5.25 inches M due to its outer diameter
It is called O or 3.5 inch MO and is distributed in the market.
The above standard also defines the size of the media hub that holds the magneto-optical disk and engages and rotates the spindle motor. When the media hub is properly placed on the hub stand of the corresponding spindle motor, the read / write of the magneto-optical disk The lights are done correctly.

On the other hand, the spindle motor has a small diameter and is made thin in order to utilize the function of an information disk such as a miniaturized magneto-optical medium. Moreover, the size of the pickup itself and the drive mechanism of the pickup do not come into contact with the spindle motor when the above-mentioned relationship between the media hub and the hub base and the pickup for reading / writing the information disc comes to the innermost circumference of the information disc. The outer diameter is restricted. For example, in the case of 5.25 inch MO, it is desirable that the outer diameter of the spindle motor is 32 mm or less, and in the case of 3.5 inch MO, it is desirably 21 mm or less. And in the volume within this outer diameter,
All functions as a drive motor are included.

A conventional example of such a magneto-optical disk spindle motor has a structure shown in FIG.

In FIG. 4, a core 4 around which a coil 5 is wound is fixedly mounted on the outer peripheral surface of the holder 16 so as to face the insulating sheet 9, while it is extended to the bottom surface of the holder 16 and is reinforced.
The substrate 6 is placed on top of this, and the magnetic sensitive element 8 is arranged to form a stator. A pair of upper and lower first ball bearings 3-1 and 3-2 are provided on the inner peripheral surface of the holder 16, and a shaft 15 serving as a spindle is supported on the inner ring of the holder 16. A drive magnet 10 which is magnetized continuously with S and N poles with a slight gap in the salient pole of the core 4 is annularly provided on the inner wall of the rotor case 11, and the edge of the rotor case 11 is on the outer peripheral side of the hub base 12. It is fixed. Further, a chucking magnet yoke 21 provided with a chucking magnet 13 is provided on the inner peripheral side of the hub base 12, and the rotor case 11,
A rotor yoke is configured with the hub base 12 and the chucking magnet yoke 21. The inner peripheral surface of the central hole 22 of the chucking magnet yoke 21 is a contact surface with the shaft 15, and the rotor yoke and the shaft 15 constitute a rotor.

By applying a drive current to the coil 5 wound around each salient pole of the core 4 of the spindle motor having such a structure, an electromagnetic interaction occurs between the drive magnet 10 and the drive magnet 10 arranged opposite to each other. Rotate. At the same time, the magnetic sensing element 8 senses the rotation speed of the rotor case 11, and the substrate 6
The rotor can be rotated at a constant speed by sending the information to a control circuit (not shown) to control the drive current.

A media hub 17 having an information disk 19 fixed at its outer peripheral portion engages an opening 18 at the center thereof with a shaft end 20, and the media hub 17 is attracted by a chucking magnet 13 so that the information media is a hub mount 12. The disk mounting surface 2 is mounted and positioned. As a result, the information disk 19 is securely fixed on the hub base 12, the motor rotates at a constant speed, and the information disk 19 can be read / written at a desired position as the motor rotates.

Standards for information media, especially the opening 18
Since the standard for the chucking magnet yoke 2 is determined, the diameter of the spindle to be engaged is also determined.
The inner diameter of the central hole 22 that is the fitting portion of the first shaft 15 is also determined. Since the fitting portion, that is, the contact surface is the inner peripheral surface of the central hole 22 of the chucking magnet yoke 21, its axial thickness is limited. In particular, if the motor is thin, it is not possible to obtain sufficient contact white, but with this limited contact white, the rotor yoke can
Must be kept at 5. With this structure, shaft 1
5 is weak when the contact surface between the chucking magnet yoke 21 and the chucking magnet yoke 21 is weak,
The chucking magnet yoke 21 may fall off the shaft. In order to prevent this drop-off, that is, to increase the fitting force, the inner diameter of the inner peripheral surface of the central hole 22 is made relatively small with respect to the diameter of the shaft 15, and when the fitting and press-fitting is performed with a strong force, the hub base surface is distorted. The flatness is deteriorated and the read / write is affected. In order to prevent these, if the dimensional tolerance is made strict, it becomes expensive.

On the other hand, it is necessary to form the motor to have a predetermined outer diameter in consideration of a pickup or the like. In this outer diameter range,
The magnetic circuit of the motor with a given torque must be constructed. Therefore, if complicated processing is performed to fix the contact surface, it is necessary to make the core 4 and the drive magnet 10 smaller by that amount. The output is weak, and the motor torque is small, so it cannot be used again.

[0010]

Therefore, according to the present invention, an output shaft portion and a small diameter portion are provided on a shaft which constitutes a spindle,
The inner ring of the ball bearing provided on the inner peripheral surface of the holder forming the stator is engaged with the small diameter portion to rotate the shaft, and the chucking magnet yoke is partially attached to the step portion from the output shaft portion to the small diameter portion. A spindle motor for information media, in which the contact force between the shaft and the rotor yoke is increased while keeping the outer shape of the motor within a predetermined size range by increasing the contact surface by contacting Is what you are trying to do.

[0011]

Therefore, the first aspect of the present invention is described.
The spindle motor includes a core around which a coil is wound, a holder for holding the core, a bearing mounted in an inner hole of the holder, a drive magnet arranged to face the core, and an information disk. In a spindle motor including a rotor yoke that is placed and rotates integrally with the drive magnet, and a shaft that is provided in the center of the rotor yoke and rotatably supported by the bearing, the shaft is outside the output shaft portion. The rotor yoke has a small-diameter portion smaller than the diameter, and a part of the rotor yoke abuts on a step formed by the output shaft portion and the small-diameter portion, and the small-diameter portion of the shaft is fitted into the central hole of the rotor yoke. It is characterized by being combined.

According to a second aspect of the present invention, in the spindle motor according to the first aspect, the rotor yoke has a standing portion extending in a cylindrical shape at a peripheral portion of the central hole, and the standing portion is provided at this standing portion. The small diameter portion of the shaft is fitted.

According to a third aspect of the present invention, in the spindle motor according to the first or second aspect, a contact surface between the step portion formed by the output shaft portion of the shaft and the small diameter portion and the rotor yoke is provided. It is characterized in that an adhesive is applied and fixed by adhesion.

[0014]

The output shaft portion and the small diameter portion are provided on the shaft forming the spindle, and the inner ring of the ball bearing provided on the inner peripheral surface of the holder forming the stator is engaged with the small diameter portion to rotate the shaft and the output shaft. It is possible to increase the contact surface by contacting a part of the chucking magnet yoke with the step portion from the portion to the small diameter portion. As a result, even if the load on the rotor yoke or the force in the pulling direction increases, the rotor yoke does not separate from the contact surface. In addition, the required torque can be obtained while the outer shape of the motor is within the predetermined size range.

The rotor yoke has a erected portion extending in a cylindrical shape at the peripheral portion of the central hole, and the small diameter portion of the shaft is fitted into this erected portion, so that the rotor yoke is provided. The adhesion strength between the shaft and the shaft is increased.

Since the contact surface formed by the output shaft portion and the small diameter portion of the rotor yoke is adhesively fixed with an adhesive, the joining force can be further increased.

[0017]

1 is a cross-sectional view showing an example of a spindle motor according to the present invention, which is in contrast to the conventional example of FIG. Members that operate in the same manner as in the conventional example are given the same reference numerals, and the description thereof is omitted.

In FIG. 1, the shaft 30 is composed of an output shaft portion 23 that engages with the opening of the media hub and a small diameter portion 24 that is smaller in diameter than the output shaft portion, and a step surface 25 is provided between the output shaft portion and the small diameter portion. Are formed. On the other hand, the central hole 2 of the chucking magnet yoke 21-1 which constitutes the rotor yoke
A standing portion 26 that extends in a cylindrical shape and into which the small-diameter portion 24 of the shaft 30 is inserted is formed at the peripheral portion of the chucking member 2. The chucking magnet yoke 21-1 passes through the step surface 25, and then the standing portion 2
6 is fitted to the upper portion of the small diameter portion 24 of the shaft 30.
The inner ring of the first ball bearing 3-1 fitted to the inner peripheral portion of the holder 16-1 is fixed to the shaft small-diameter portion 24 below the upright portion 26, and the inner ring upper surface 31 and the step surface 25 thereof are fixed.
And holds the standing portion 26.

At the time of assembly, by applying the adhesive 27 to the step surface 25 and the standing portion 26 and then engaging with the shaft 30, the shaft 30 and the chucking magnet yoke 21.
The contact of -1 can be further strengthened.

According to this structure, the chucking magnet yoke 21-1 abuts the shaft 30 over a wide area through the step surface 25 and the upright portion 26, and the chucking magnet yoke 21-1 has a step surface. When the disk is attached or detached, even if a strong axial force is applied to the chucking magnet yoke 21-1 when the disk is attached or detached, it is detached from the shaft 30. Never. Also,
Even if the disc is repeatedly attached and detached, there is no fear that the disc mounting surface will be displaced or come off.

Further, as compared with the conventional example, the ball bearing supporting the small diameter portion 24 can use a small standard product. As a result, the coil 5, the core 4 around which the coil 5 is wound, and the members constituting the magnetic circuit, such as the drive magnet, can be made large within the desired dimensions, so that the torque of the spindle motor can be increased. .

FIG. 2 is a sectional view of the essential parts showing another embodiment of the spindle motor of the present invention. A description of the shaft shown in FIG. 1 and a description overlapping with the conventional example shown in FIG. 4 will be omitted.

In FIG. 2, the chucking magnet yoke 21-2 is provided with a central hole 22 which fits into a small diameter portion 24 having a diameter smaller than that of the output shaft portion 23, and the stepped surface 25 of the shaft 30 near the central hole 22. And the first ball bearing 3-1
It can be held by a washer 29 provided on the upper portion of the inner ring, and can also be held after the adhesive 27 is applied to the step surface 25 and the standing portion 26 if necessary.

In this state, even if a strong force is applied to the chucking magnet yoke 21-2 from above in the drawing when the disc is attached and detached, the held state is reliably maintained.

FIG. 3 is a sectional view of a main portion showing another embodiment of the spindle motor of the present invention. The description shown in FIG. 1 and the description overlapping with the conventional example shown in FIG. 4 will be omitted.

In FIG. 3, a tip end of the chucking magnet yoke 21-3 forming the rotor yoke 21-3 extends in a cylindrical shape at the inner peripheral portion thereof, and the standing portion 26 has a longer extension than that shown in FIG. -1 is formed, the chucking magnet yoke 21-3 passes through the step surface 25, and the standing portion 26-
No. 1 is fitted to the small diameter portion 24 of the shaft 30. The first ball bearing 3-1 is provided on the inner peripheral portion of the holder 16-2.
And the second ball bearing 3-2 are fitted to each other, and the inner ring of the first ball bearing 3-1 is fixed to the outer peripheral surface of the standing portion 26-1 while the second ball bearing 3-2 is fixed. The inner ring of is fixed to the small diameter portion 24, and the end portion 28 of the standing portion is the second portion.
The ball bearing 3-2 is held by the upper part of the inner ring. If necessary, the adhesive 27 may be applied to the step surface 25 and the standing portion 26-1 and then held.

The contact surface of the chucking magnet yoke 21-3 extends from the step surface 25 to the standing portion 26-1, and since it is wide, the gripping state is surely maintained even if a force is repeatedly applied to the disk mounting surface. To be done.

[0028]

The shaft constituting the spindle of the present invention is provided with the output shaft portion and the small diameter portion, and the inner ring of the ball bearing provided on the inner peripheral surface of the holder is engaged with the small diameter portion to rotate the shaft and to output the output. It is possible to increase the joining surface by making a part of the chucking magnet yoke abut on the step portion from the shaft portion to the small diameter portion, thereby increasing the joining force. Also, a cylindrical standing portion is provided on the peripheral portion of the central hole,
By fitting the shaft to the upright portion, the joining force between the shaft and the chucking magnet yoke can be further increased. Furthermore, if desired, the contact surface formed by the output shaft portion and the small diameter portion is adhered to further increase the joining force, and even if the disk is repeatedly attached to and detached from the chucking magnet yoke, the disk mounting surface It is possible to prevent slippage and dropout.

Since the ball bearing engages with the small diameter portion, a small one can be used. As a result, the space for accommodating the members constituting the magnetic circuit becomes wider, so that the required torque can be obtained while keeping the outer shape of the motor within the predetermined dimension range.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a spindle motor according to the present invention.

FIG. 2 is a sectional view of an essential part of another embodiment of the spindle motor according to the present invention.

FIG. 3 is a sectional view of a main part of another embodiment of the spindle motor according to the present invention.

FIG. 4 is a sectional view of a conventional example of a spindle motor.

[Explanation of symbols]

 16-1 Holder 21-1 Chucking Magnet Yoke 23 Output Shaft Part 24 Small Diameter Part 25 Stepped Surface 26 Standing Part 30 Shaft

Claims (3)

[Claims] 1. A core around which a coil is wound, a holder for holding the core, a bearing mounted in an inner hole of the holder, a drive magnet arranged to face the core, and an information disk are mounted. Then, in a spindle motor comprising a rotor yoke that rotates integrally with the drive magnet and a shaft that is provided in the center of the rotor yoke and rotatably supported by the bearing, the shaft is larger than the outer diameter of the output shaft portion. Also has a small diameter portion with a small diameter, a part of the rotor yoke abuts on a step portion formed by the output shaft portion and the small diameter portion, and the small diameter portion of the shaft is fitted in the central hole of the rotor yoke. The spindle motor is characterized by having. 2. The spindle motor according to claim 1, wherein the rotor yoke has a standing portion extending in a cylindrical shape at a peripheral portion of the central hole, and the standing portion has a small diameter portion of the shaft. A spindle motor characterized by being fitted. 3. An adhesive is applied to the contact surface between the step portion formed by the output shaft portion and the small diameter portion of the shaft and the rotor yoke, and is fixed by adhesion. Item 1. The spindle motor according to Item 1 or 2.