KR100420316B1 - Structure of anti-vibration spindle motor - Google Patents

Abstract

PURPOSE: A structure of a vibration preventing spindle motor is provided to reduce vibrations of the motor by reducing a torque ripple and cogging torque ripple. CONSTITUTION: A structure comprises a stator assembly(110) including a coil for applying a current; a rotor assembly(130) including a rotating shaft(136) which rotates when a current is applied to the coil; and a damping unit(150) including a disk(152) mounted in a horizontal direction on the rotating shaft, a housing(160) covering the disk, and a damping oil(156) having a constant viscosity coefficient, and which fills the housing. The damping unit applies a constant load to the rotating shaft regardless of the rotating speed of the rotating shaft. The housing includes a printed circuit board through which the lower end of the rotating shaft penetrates, and a cover mounted on the lower portion of the printed circuit board.

Description

Structure of anti-vibration spindle motor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a spindle motor for preventing vibration, and more particularly, it relates to a structure of a spindle motor for preventing vibration, and more particularly, to reduce torque ripple and cogging torque ripple to suppress vibration inside a motor, The present invention relates to a structure of a spindle motor configured to have vibration absorbing capability.

First, the structure of a conventional spindle motor and related torque ripple and cogging torque ripple will be described with reference to FIG. 1.

The spindle motor largely consists of a rotor and a stator that keeps a fixed state for applying a rotational force to the rotor. The stator includes a coil 16 for generating a rotational force, a yoke 12 for winding the coil 16, and a plurality of bearings for supporting the rotational state of the rotating shaft 26 at the center of the yoke 12. [ (14), and the like. In the illustrated embodiment, the coil 16 is shown electrically integrated with a steel printed circuit board 18 coupled at the lower end of the yoke 12. The steel printed The required circuit is directly patterned on the circuit board 18 and fixed to the main base 10 of the motor.

A rotor, which is rotated by an electromagnetic force generated by a current applied to the coil 16 of the stator, is coupled to the outside of the stator. The rotor includes a magnet 24 rotating by a current applied to the coil 16, a rotor 22 for attaching the magnet 24 to the inner periphery of the rotor 22, And a rotating shaft 26 rotating together.

The lower end of the rotating shaft 26 is supported by the steel printed circuit board 18 so as to extend through the steel printed circuit board 18. The lower end of the rotating shaft 26 extends from the lower surface of the steel printed circuit board 18, (19) is press-fitted into the rotation shaft.

When a current is applied to the coil 16 through the steel printed circuit board 18 in the conventional spindle motor thus configured, the rotor 22 and the shaft are fixed to the center of the rotor 22 by the electromagnetic force generated between the coil and the magnet. The rotating shaft 26 is rotated.

The rotation of the rotary shaft 26 also rotates the turntable 28 fixed to the upper end thereof. If such a spindle motor is used as a rotating means for reading the recording surface of an optical disc such as a CD or an LD, an optical disc is mounted on the top surface of the turntable 28 and rotated, An optical pickup device will be installed.

In the spindle motor having such a configuration, the turntable rotating as the rotating shaft has a problem that vibration is generated by torque ripple and cogging torque ripple. The torque ripple and the cogging torque ripple are generated due to different configurations of the spindle motor and currents applied to the spindle motor in order to drive the spindle motor.

The cogging torque ripple occurs even when no current is applied to the spindle motor, and the same polarity is applied to the yoke corresponding to the predetermined N pole or S pole of the magnet 22. At this time, As the position of the polarity changes, the cogging torque ripple is generated between the rotor and the stator due to the attraction and repulsion force at that moment.

The torque ripple is generated while the current is applied to the coil and is rotated, and three-phase DC is applied to operate the spindle motor. The three-phase direct current applied at this time has a phase difference of 120 degrees, and as a result of this phase difference, it appears as an unnecessary induction signal to each other's signal. Such torque ripple appears relatively large as compared with the cogging torque ripple, causes vibration and noise on the rotary shaft, and adversely affects other electrical characteristics. When the spindle motor is used in a device for reproducing a recording medium, vibration generated by ripples is transmitted to a disk mounted on a turntable or to a pickup through a main base, resulting in degradation of recording and reproduction.

Particularly, in a device for reproducing a digital video disk (DVD) having a higher recording density than a CD and an LD, such vibration may have a great adverse effect on recording and reproduction. In the case of a DVD, the recording density is much higher than that of the conventional CD, and about 5 gigabytes (Gbytes) is recorded for one-side recording on the same size disc. In the case of a turntable and a pickup used for reproducing such a high- It is desirable to minimize the influence of the vibration caused by the ripple of the liquid.

The conventional spindle motor does not have a mechanical means capable of absorbing or suppressing vibration due to the internal structure of the spindle motor and the torque ripple caused by the driving current and the cogging torque ripple. In addition, it is a reality that a mechanical device capable of absorbing or suppressing vibrations caused by disturbance is not provided.

It is an object of the present invention to provide a structure of a spindle motor suitable for the reproduction of a high density recording medium, because it can absorb or suppress vibration due to internal vibration and disturbance caused by ripple of the spindle motor.

FIG. 1 is a sectional view showing a schematic structure of a conventional spindle motor. FIG.

FIG. 2 is a sectional view showing a structure of a spindle motor according to the present invention; FIG.

FIG. 3 is a graph comparing the amount of generated torque ripple with respect to the present invention and the related art,

(A) is a graph showing the amount of torque ripple generated by the conventional structure.

(B) is a graph showing the amount of torque ripple generated by the structure of the present invention.

Description of the Related Art [0002]

110 .... stator assembly 114 .... York

116 .... bearing 118 .... metal printed circuit board

120 .... Main base 130 .... Rotor assembly

132 .... rotor 134 .... magnet

136 .... Rotation shaft 138 .... Turntable

150 .... damping device 152 .... disk disk

154 .... cover 156 .... damping oil

160 .... housing

According to an aspect of the present invention, there is provided a stator assembly comprising: a stator assembly including a coil part for applying current; A rotor assembly including a rotating shaft that rotates when a current is applied to the coil; The present invention relates to a disk drive, comprising: a disk for mounting a constant load on a rotating shaft irrespective of a rotational speed of the rotating shaft; a disk mounted horizontally on a rotating shaft; a housing surrounding the disk; And damping means composed of damping oil.

The housing includes a steel printed circuit board through which a lower end of a rotating shaft passes, and a cover mounted on a lower portion of the steel printed circuit board while making a certain space filled with damping oil.

According to the structure of the spindle motor according to the present invention, the generation amount of the vibration itself is reduced by suppressing the amount of torque ripple generated, and the generated vibration can be absorbed by the damping device. At the same time, the damping device according to the present invention is capable of absorbing not only vibrations due to internal factors such as ripples, but also vibrations caused by disturbance to some extent, It can be particularly useful for the reproduction of the medium.

Hereinafter, the present invention will be described in more detail based on preferred embodiments shown in the drawings.

2, the spindle motor according to the present invention includes a stator assembly 110, a rotor assembly 130, and a damping unit 130 for providing a constant load to the rotor assembly 130, Device 150 as shown in FIG.

The stator assembly 110 according to the present invention includes a coil 112 to which a current is applied, a yoke 114 for winding the coil, a steel printed circuit (not shown) electrically connected to the coil 112, And a substrate 118. The steel printed circuit board 118 electrically connected to the coil 112 has a predetermined copper foil pattern and is fixed to the lower surface of the yoke 114. The lower surface of the steel printed circuit board 118 is fixed to the main base 120. Although the coils 112 are shown as a pair for convenience of illustration, a plurality of coils 112 are designed to apply currents having different phases.

The rotor assembly 130 includes a magnet 134 located on the opposite side of the coil 112, a rotor 132 attached to the inner periphery of the magnet 134, And a rotating shaft 136 that is fixed to the shaft and rotates together. A turntable 138 is coupled to the upper end of the rotation shaft 136 to rotate together. The turntable 138 seats a disc for reproduction on its upper surface. The turntable 138 is provided at its center with a guide pin 140 having a top edge for guiding a disc such as a CD or a DVD, And is press-fitted.

The lower end of the rotating shaft 136 is supported through the center of the steel printed circuit board 118 and is rotatably supported by a plurality of bearings 116 at the center of the yoke 114.

Next, the damping device 150, which is a main part of the present invention, will be described.

The damping device 150 is for substantially applying a certain load to the rotating shaft 136 which is rotating. It is somewhat disadvantageous in terms of efficiency of a spindle motor that requires high speed rotation to apply a constant load to the rotating shaft 136. However, the rotational efficiency of such a motor can be solved by adjusting the power applied to the motor It is. However, as described above, precise control is required as in the reproduction of a DVD, which is a high-density optical recording medium, and when the vibration due to the ripple of the spindle motor has a more fatal effect on recording and reproduction, , It is natural that the stable and accurate recording reproduction is more important. It is known that the above-mentioned ripple is reduced if a certain load is applied to the rotating rotary shaft, and the present invention is focused on this point.

However, there is one important condition to reduce the ripple by applying a constant load to the rotating shaft. And the load applied to the rotating shaft must be constant regardless of the rotational speed. A damping device 150 according to the present invention will be described with reference to an embodiment satisfying these conditions with reference to FIG.

A damping device 150 according to the present invention includes a disk 152 that is horizontally inserted into a lower end of a rotation shaft 136, a housing 160 that can include the disk 152, And a damping oil 156 having a predetermined viscosity with respect to the contact area with the disc 152. In the illustrated embodiment, the housing 160 is realized with a cover 154 secured by bolts 162, forming a space at the lower end of the steel printed circuit board 118.

The disk disk 152 pushed horizontally into the rotary shaft 136 will be described in detail. The disk disk 152 maintains a constant area in the horizontal direction and this area provides a contact surface with the damping oil 156 in the housing fastener 160 so that it can be kept constant by the viscosity coefficient of the damping oil during rotation of the rotary shaft And acts as a load. Here, the constant load means that the load must act as a constant load irrespective of the rotational speed of the rotating shaft 136. This means that the damping oil 156 having a viscosity coefficient has a constant viscosity regardless of the rotational speed of the rotational shaft 136, that is, the viscosity coefficient does not change with the rotational speed of the rotational shaft 136, Is based on the fact that the disc disc 152 is always in contact with the damping oil 156 at a constant area. Therefore, the damping oil 156 having a constant viscosity constant always applies a constant load to the rotation shaft 136 irrespective of the rotation speed of the rotation shaft 136.

Here, the operation of the other one of the discs 152 will be described. As described above, the disk disk 152 maintains the horizontal state, and the area in the horizontal direction in contact with the damping oil 156 is much larger than the area in the vertical direction. Therefore, the damping oil 156 acts as a considerably large resistance against the movement of the rotary shaft 136 in the vertical direction. Accordingly, the disc 152 may serve as a washer for preventing the rotation shaft from falling down, as compared with the conventional structure.

In the description of the structure of the anti-vibration spindle motor according to the present invention, the damping device 150 is implemented at the lower end of the rotary shaft. However, the damping device 150 according to the present invention can not be limited in its position. That is, irrespective of the rotational speed of the rotating shaft, it is also possible to apply the same to other portions of the rotating shaft within a range in which a constant load can be applied to the rotating shaft. Also, the damping device 150 shows only one embodiment in which a constant load can be always applied to the rotary shaft or the one shaft of the rotor assembly regardless of the rotational speed of the rotary shaft.

According to the structure of the anti-vibration spindle motor of the present invention configured as described above, the following operational effects can be expected.

First, as described above, the damping device 150 according to the present invention is provided with a constant-sized load on the rotating shaft regardless of the rotating speed of the rotating shaft. Therefore, since there is no change in the load, The required rotational speed can be sufficiently maintained by controlling the electric power, and the amount of generated torque ripple can be reduced compared to the conventional one due to the provision of a constant load.

The difference in the amount of generated torque ripple and cogging torque ripple is shown in FIG. Fig. 3 (A) shows the amount of ripple generated by the conventional structure, Fig. 2 (B) shows the ripples generated in the structure according to the present invention, and the upper end shows torque ripple and the lower end shows cogging torque ripple .

As shown in the figure, it can be seen that the amount of generated torque ripple according to the present invention is smaller than the conventional one. That is, it can be seen that the amplitude h2 of the torque ripple according to the present invention is much smaller than the amplitude h1 of the torque ripple according to the conventional structure, which is the same as the fact that the average torque ripple is decreasing in size . Also, the cogging torque ripple can be made much smaller than the conventional amplitude (H1) according to the present invention.

3 shows that the structure of the spindle motor according to the present invention means that the damping device 150 significantly reduces the torque ripple and the cogging torque ripple caused by factors inside the motor, This means that the vibration due to the ripple generated inside the spindle motor is decreasing. As described above, according to the present invention, there is an effect of suppressing a generation factor of vibration with respect to vibration generated inside the spindle motor.

The damping device according to the present invention is a fluid having a constant viscosity. And fluid with constant viscosity has the property to absorb vibration within a certain range in mechanical device. This fact, though reduced, means that by absorbing a part of the vibration due to the remaining ripples, it is possible to provide a spindle motor that is substantially bonded to the reproduction of a high-density recording medium such as DVD.

So far, the effect of suppressing or absorbing the generation of vibration due to the internal factors of the spindle motor has been mentioned. In addition to suppressing or absorbing the internal vibration, the damping device according to the present invention can absorb vibration generated in the spindle motor due to disturbance, or vibration occurring in the optical disk reproducing device using the spindle motor due to disturbance Effect can be expected.

Claims (2)

A stator assembly including a coil portion for applying current; A rotor assembly including a rotating shaft that rotates when a current is applied to the coil; And A disk which is mounted horizontally on a rotating shaft for hanging a constant load on a rotating shaft regardless of a rotating speed of the rotating shaft; a housing which encloses the disk; a damping Wherein the vibration damping means comprises a damping means composed of an oil. 2. The apparatus of claim 1, wherein the housing comprises: A steel printed circuit board through which the lower end of the rotating shaft penetrates; and a cover mounted on a lower portion of the steel printed circuit board while making a certain space filled with damping oil.