JP2001023288A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent the run-out of a rotor and to prevent the dislodgment thereof by providing the spindle motor with a stopper having an annular trough for freely revolvably and rotatably housing balancing balls in its outer peripheral part and detaining parts for engaging with the projecting part of a bearing housing on an inner side, thereby providing a rotor dislodgment preventive mechanism and balance mechanism in combination. SOLUTION: When a medium disk is placed on the spindle motor and the spindle motor is driven, the force tending to rotate in a transverse direction against the rigidity of a bearing 5 acts on a revolving shaft 6 by the cause for the slight unbalance possessed by the medium disk with an increase in the rotating speed. The balls housed in the annular trough 11b roll to a balancing direction and stop at the position, thereby acting reverse from the force tending to cause the axial run-out and wobbling of surface and attaining the balance. A turn table tends to be dislodged by overcoming the attraction force of a magnet 9 and a stator core but when the rotor floats up, the second detaining part 1a is engaged with the first detaining part 10a of the bearing housing 10 and is downwardly pushed back.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a CD-ROM,
The present invention relates to a spindle motor having a turntable suitable for driving a media disk such as a DVD-ROM.
In particular, the present invention relates to a mechanism which functions as a balance mechanism and a mechanism for preventing the rotor portion from being separated.

[0002]

2. Description of the Related Art Conventionally, media disks such as CDs have increased in data capacity as their applications have expanded for computers, and in order to cope with this, high speed has been required. Then, a speed of 20 times or more is realized. Here, a specific structure of a conventional disk drive spindle motor will be described with reference to FIG. In FIG. 2, 1 is a stator base, 2 is a bearing housing implanted in the center of the stator base 1, 3 is a stator core fixed to the outer periphery of the bearing housing 2,
Reference numeral 4 denotes a coil wound around the stator core 3. Reference numeral 5 denotes a bearing fixed to the inner periphery of the bearing housing 2 by a method such as press fitting. Reference numeral 6 denotes a rotary shaft supported by the bearing 5, and reference numeral 7 denotes a turntable fixed to an output end of the rotary shaft 6, which has a ring-shaped media disk mounting table 7a on its surface. A rotor case 8 is fixed to a lower portion of the rotating shaft 6 to which the turntable 7 is fixed, and a magnet 9 is fixed to an inner periphery of the rotor case 8.

The disk driving spindle motor constructed as described above is attracted to each other by the deviation z between the center of the magnetic pole of the magnet 9 and the center of the magnetic pole of the stator core 3 so that the rotating shaft does not come off the bearing even if the rotor rotates. It is.

[0004]

However, when the rotor is driven at a speed of 20 times speed or more, a slight manufacturing error or assembling error of each component causes a problem that does not occur at low speed rotation. For example, problems such as surface run-out, vibration, noise during high-speed rotation, shortening of the life associated therewith, separation of the rotor, etc. are unavoidable. Was dangerous and could not be ignored.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a spindle motor having a turntable suitable for driving a media disk and to prevent the rotor from swinging and separating.

[0006]

In order to solve the above-mentioned problems, an outer rotor type motor having a turntable at one end of a rotary shaft and a mechanism for preventing the rotor from falling off is provided with an outer periphery inside a rotor case. A stopper made of an elastic material having an annular gutter for accommodating the balancing ball so that it can revolve and rotate freely, and a locking portion inwardly engaged with the convex portion of the bearing housing. This can be achieved by also serving as a balance mechanism.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a first embodiment of a spindle motor having a turntable according to the present invention. FIG. 2 is a plan view showing the stopper for preventing detachment in detail. 1 and 2, reference numeral 1 denotes a stator base, and 10 denotes a bearing housing implanted in the center of the stator base 1 and has a first locking portion 10a on the outer periphery on the free end side. Reference numeral 3 denotes a stator core fixed to the outer periphery of the bearing housing 10, and reference numeral 4 denotes a coil wound around the stator core 3. Reference numeral 5 denotes a bearing fixed to the inner periphery of the bearing housing 10 by press-fitting or the like. In this embodiment, the bearing is illustrated as an oil-impregnated bearing, but may be a ball bearing or a roller bearing. Reference numeral 6 denotes a rotary shaft supported by the bearing 5, and reference numeral 7 denotes a turntable fixed to an output end of the rotary shaft 6, which has a ring-shaped media disk mounting table 7a on its surface. The rotating shaft 6
A rotor case 8 having a plurality of release through holes 8a on the upper surface is fixed to a lower portion where the turntable 7 is fixed.
A magnet 9 is fixed to the inner periphery of the rotor case 8. Numeral 11 is fixed to the inner upper surface of the rotor case 8 by press-fitting or the like. When the rotor R (including the rotating shaft 6 and the turntable 7 and the rotor case 8 fixed to the rotating shaft 6) rotates at a high speed, this rotor R R is formed in a substantially annular shape by a stopper for preventing detachment from the stator S (FIG. 2), and engages with a first locking portion 10a provided on the outer periphery of the bearing housing 10 around the central through hole. At least two pieces of the second locking portion 11a are provided. Protrusions 11c corresponding to the release through-holes 8a provided on the upper surface of the rotor case 8 are provided in the vicinity of the second locking portions 11a, and are pressed by projections or the like through the release through-holes 8a. As a result, the second locking portion 11a is bent outward, disengaged from the engagement position with the first locking portion 10a, and the rotor R can be removed from the bearing housing 10. Second locking part 11
a is desirably formed of an elastic material such as a leaf spring or plastic. Further, an annular gutter 11b is provided on the outer periphery. Therefore, it is advantageous in terms of operability and cost that the entire stopper 11 is made of an elastic material. 1
2 is a balance ball made of a high specific gravity material. A required number of balancing balls 12 are put into the annular gutter 11b, and the stopper 11 is mounted inside the rotor case 8 by press fitting or the like. In this state, the balancing ball 12 can freely move in the annular gutter 11b of the stopper 11.

Now, when a media disk is mounted on a spindle motor constructed as described above and driven, as the rotational speed increases, the rigidity of the bearing 5 on the rotating shaft 6 due to a slight imbalance of the media disk increases. A force that tries to rotate in the lateral direction (revolution) against the force acts. For this reason, shaft runout and surface runout tend to occur. However,
Since the ball accommodated in the annular gutter 11b rolls in the balance direction and stops at that position, the ball works in a direction opposite to the force for causing the shaft runout and the surface runout to balance. Further, as the rotation speed increases, the turntable tends to separate against the attraction force of the magnet 9 and the stator core. However, when the rotor is lifted, the second locking portion 11a engages the first locking portion 11a of the bearing housing 10. Because it is engaged with the part 10a, it is not pulled back and separated.

Next, FIG. 3 is a partial sectional view showing a second embodiment of a spindle motor having a turntable according to the present invention. In FIG. 3, the same portions are denoted by the same reference numerals. In the figure, reference numeral 13 denotes a bearing housing, which is implanted in the center of the stator base 1 and only a part of the free end protrudes outward in a flange shape.
It has a third locking portion 13a that engages with 1a. The above-mentioned first locking portion 10 a is
a, but the third locking portion 13a has no recess adjacent to the third locking portion 13a.
3 is the same as the first locking portion 10a except that only the locking portion protrudes from the outer periphery of 3. Next, the rotor R is connected to the stator S
When removing from the bearing housing 13, the protrusion 11 a of the release lever 14 is inserted and pressed through the release through hole 8 a provided on the upper surface of the rotor case 8, whereby the protrusion 11 c is pressed down, and accordingly, the second protrusion 11 c is pressed. Locking part 11a
Is deflected outward, and comes out of the engagement position with the first locking portion 10a. In this state, the rotor R (rotary shaft 6) may be pulled out of the stator S (bearing 5). Thus, the rotor R can be removed from the bearing housing 10.

In the second embodiment as well, as the spindle motor rotates at a higher speed, a force is applied to the rotor to lift up or cause shaft runout and surface runout due to slight imbalance of the media disk. However, since the second locking portion 11a engages with the first locking portion 10a of the bearing housing 10, the plurality of balls accommodated in the annular gutter 11b roll in the balance direction while being pulled back downward, It balances with the force that causes shaft runout and surface runout. In addition, even if the media disk actually has a slight cause of imbalance, the annular gutter 1
Since the ball accommodated in 1b rolls in the balance direction and suppresses shaft runout and surface runout, the second locking portion 11a
However, the rotor hardly rises until it engages with the first locking portion 10a of the bearing housing 10.

[0011]

According to the present invention, as described above, in an outer rotor type motor having a turntable at one end of a rotating shaft and a mechanism for preventing the rotor from falling off, a balancing ball is provided inside a rotor case and at an outer peripheral portion. A stopper made of an elastic material having an annular gutter that freely accommodates the revolution and a locking portion that engages with the protrusion of the bearing housing inward,
By using this stopper as a rotor drop-out prevention mechanism and a balance mechanism, it is possible to prevent problems such as surface runout, vibration and noise during high-speed rotation, shortening of the life associated therewith, and separation of the rotor.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a first embodiment of a spindle motor including a turntable according to the present invention.

FIG. 2 is a plan view showing a detachment stopper in detail.

FIG. 3 is a partial cross-sectional view showing a second embodiment of a spindle motor having a turntable according to the present invention.

FIG. 4 is a partial sectional view showing a specific structure of a conventional disk drive spindle motor.

[Explanation of symbols]

 R Rotor 1 Stator base 3 Stator core 4 Coil 5 Bearing 6 Rotating shaft 7 Turntable 8 Rotor case 9 Magnet 10, 13 Bearing housing 11 Stopper 12 Balancing ball

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[Procedure amendment]

[Submission date] July 13, 1999 (1999.7.1)
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[Document name to be amended] Drawing

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[Document name to be amended] Drawing

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FIG. 3

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[Document name to be amended] Drawing

[Correction target item name] Fig. 4

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Claims (2)

[Claims] 1. An outer rotor type motor having a turntable at one end of a rotating shaft and a mechanism for preventing a rotor from falling off, wherein an annular gutter for accommodating a revolving ball in an outer peripheral portion is provided inside a rotor case. A spindle motor, comprising: a stopper having a locking portion that engages with a projection of a bearing housing inward, and the stopper serves as a rotor drop-out prevention mechanism and a balance mechanism. 2. The spindle motor according to claim 1, wherein said stopper is made of an elastic material.