JPH11136899A - Spindle motor shaft runout preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain size reduction in a spindle motor shaft runout preventing device which has a spindle motor constituted of very small parts as a driving source. SOLUTION: A spindle motor 1 is fixed on a seating plate 3, and a driving shaft 2 is introduced in a through hole 7 formed at the seating plate 3. A cylindrical bush 8 is fitted to the driving shaft 2, and a torsion coil spring 9 is fitted to its outer periphery. The arm parts 9A, 9A of the torsion coil spring 9 are locked at the section of the seating plate 3, and the bush 8 is forced in the radial direction of the driving shaft 2 by its restoring force. Therefore, by fitting the bush 8 and the torsion coil spring 9 in the fitting area of the spindle motor 8, it is possible to prevent the runout of the driving shaft 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing shaft runout of a spindle motor used in audio equipment, and more particularly to a spindle motor suitable for a spindle motor (step motor) for driving a disk-shaped recording medium such as a compact disk. The present invention relates to a shaft runout prevention device for a motor.

[0002]

2. Description of the Related Art Generally, a large number of electric motors are used for electric equipment and the like, but a spindle motor is often used for a control system which requires high precision in speed and positioning of a drive unit. For example, in a disk reproducing apparatus for reproducing a disk-shaped recording medium such as a compact disk, a spindle motor is generally widely used as a drive source for driving the disk-shaped recording medium. Most of them are of a direct drive type directly connected to a turntable on which a disk-shaped recording medium is mounted, and can accurately control the rotation speed of the disk-shaped recording medium according to an input pulse to a spindle motor. Here, a recent disk-shaped recording medium is a digital recording type in which pits are formed in a spiral shape along the disk surface, and the pit row, that is, the width of the track is 0.5 μm, and the pitch is 1.6 μm. The pit detecting pickup is configured to move accurately along the disk surface in accordance with the rotation speed of the spindle motor. However, the rotation of the disk-shaped recording medium is The movement is not stable, and the trajectory of the track is displaced, which impairs the reproduction state such as sound skipping.

Therefore, conventionally, in order to prevent shaft runout of the spindle motor, as shown in FIG.
The lever L is swingably provided on a seat plate for fixing the spindle motor M adjacent to the spindle motor M, and its free end is pressed against the outer periphery of the drive shaft m of the spindle motor M with the elasticity of the tension coil spring S.

[0004]

However, using a lever extending toward the spindle motor involves the following:
The installation requires a considerable installation area, which adversely affects the miniaturization of the entire apparatus such as a disk reproducing apparatus having a spindle motor as a drive source. In addition, when the area occupied by the lever and the extension coil spring is increased, the design must be performed in consideration of the positional relationship with other components, and the like, so that the design difficulty increases.

Accordingly, an object of the present invention is to make it possible to prevent shaft runout of a spindle motor by using a very small part which takes up little space.

[0006]

According to the present invention, there is provided a bush which is slidably fitted to a drive shaft of a spindle motor, a torsion coil spring provided on an outer periphery of the bush, and A locking portion that locks both ends of the torsion coil spring formed on a seat plate that fixes a spindle motor, such that the bush is urged in the radial direction of the drive shaft by the elastic force of the torsion coil spring. An object of the present invention is to provide an apparatus for preventing shaft runout of a spindle motor.

According to a second aspect of the present invention, a flange is formed at one end of the bush.

[0008]

According to the present invention, the elastic force of the torsion coil spring acts on the bush fitted on the drive shaft of the spindle motor, and the bush is urged in the radial direction of the drive shaft of the spindle motor. For this reason, lateral pressure is applied to the drive shaft by the bush in the urging direction. Therefore, the directivity of the drive shaft is improved and shaft runout during rotation is prevented. Here, since the bush is fitted to the drive shaft, no space is required for installation.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, FIG. 1 is an exploded perspective view showing a preferred example of an apparatus for preventing shaft runout of a spindle motor according to the present invention. In FIG. 1, reference numeral 1 denotes a spindle motor, and 2 denotes a drive shaft thereof.
Is connected to a pulse generation circuit (not shown) and can drive the drive shaft 2 at a rotation speed corresponding to the input pulse.

Reference numeral 3 denotes a seat plate for fixing the spindle motor 1, and the seat plate 3 is formed of, for example, a thermoplastic resin or other synthetic resin. The seat plate 3 is provided with a through hole 5 corresponding to a screw hole 4 formed on the upper end surface of the spindle motor 1, and a screw 6 is screwed into the screw hole 4 from the through hole 5 to form a spindle. The motor 1 can be fixed.

Reference numeral 7 denotes a circular through hole formed in the seat plate, and the drive shaft 2 of the spindle motor 1 is introduced into the through hole 7. The diameter of the through hole 7 is larger than the diameter of the drive shaft 2 of the spindle motor 1 and does not hinder the rotational drive of the drive shaft 2. Particularly, in this embodiment, the cylindrical bush 8 and the torsion coil spring 9 can be accommodated in the through hole 7. Specifically, the shaft diameter of the drive shaft 2 of the spindle motor 1 is 1.5 mm, and the through hole 7 has a diameter of 5 m.
Although the diameter of the through hole 7 is determined by the size of the spindle motor 1 and is not particularly limited, the diameter of the through hole 7 should be at least twice the diameter of the drive shaft 2 in terms of accommodating the bush 8. preferable.

Here, the bush 8 is made of, for example, synthetic resin and is fitted to the drive shaft 2 of the spindle motor 1. Its inner diameter is slightly larger than the shaft diameter of the drive shaft 2 of the spindle motor, and is slidably fitted to the drive shaft. Further, the bush 8 has a flange 8A formed at one end thereof, and is fitted to the drive shaft 2 with the flange 8A facing upward. The bush 8 is preferably made of a synthetic resin in consideration of the heat generated by friction with the drive shaft 2. However, even if the bush 8 is made of metal, the use of grease or other lubricant between the bush 8 and the drive shaft 2 reduces the friction heat. Generation can be suppressed.

On the other hand, the torsion coil spring 9 is of a straight type in which the arms 9A, 9A at both ends extend in a V-shape from the coil 9B. Is housed inside. At this time, the arms 9A, 9A are resiliently locked to the portion of the seat plate 3.

In FIG. 1, reference numeral 10 denotes a mounting hole for fixing the seat plate 3 at a predetermined position, and reference numeral 11 denotes a cutout groove formed along the through hole 7. The cutout groove 11 has a torsion coil spring 9. A locking portion for locking the arm portions 9A, 9A is formed.

Next, FIG. 2 shows a state in which the parts are assembled. As clearly shown in this figure, guide grooves 13 are formed in a partition wall 12 that separates the through hole 7 from the notch groove 11, and the guide grooves 13 are engaged with the arm portions 9 A of the torsion coil spring 9 through the guide grooves 13. It is locked to the stoppers 14, 14. Here, the locking portion 14 is formed integrally with the seat plate 3 so as to be narrower than the gap between the arms 9A, 9A of the torsion coil spring at the time of no load, and the arms 9A, 9A of the torsion coil spring are formed here. It is secured firmly by restoring force.

Therefore, as shown in FIG. 3, a reaction force F acts on the coil portion 9B of the torsion coil spring 9 with respect to the restoring force P of the arms 9A, 9A. Therefore,
Bush 8 provided with the torsion coil spring 9 on the outer periphery
Is urged in the radial direction of the drive shaft 2 of the spindle motor 1 by the reaction force F to apply a lateral pressure to the drive shaft 2. Then, when a pulse is input to the spindle motor 1 in this state, the drive shaft 2 is driven stably at a rotational speed according to the input pulse with directivity without a run-out.

Here, this kind of spindle motor 1 is mounted on various kinds of electric equipment, and can make each drive unit perform a definite movement as a drive source. As a preferable example, use as a drive source in a disk reproducing device such as a CD player or an MD player is considered. In FIG. 4, the outline is described. Reference numeral 15 denotes a chassis of a drive unit for driving the disk D. The chassis 15 includes a pickup (not shown) for reading recorded information of the disk D as a digital recording medium and a drive mechanism thereof. In addition, the seat plate 3 is detachably fixed to a predetermined position of the chassis 15 with a mounting hole 10 shown in FIG. A turntable T for supporting the disk D is mounted on the drive shaft 2 of the spindle motor fixed to the seat plate 3.
Attach.

According to this embodiment, when the turntable T is rotated through the drive shaft 2 of the spindle motor 1, the turntable T and the disk D are stabilized around one point by the side pressure action of the bush 8 on the drive shaft 2. The pit recorded on the disk D can be properly read by the pickup because the rotating motion is performed. For this reason, there is no skipping or other reproduction defects, and the reproduction accuracy is greatly improved.

As apparent from FIG. 4, the bush 8 fitted to the drive shaft 2 can be disposed in a non-contact manner with the upper end surface of the spindle motor 1 because the flange 8A is supported by the torsion coil spring 9. . If the bush 8 does not contact the part other than the drive shaft 2 of the spindle motor, the elasticity of the torsion coil spring 9 can be transmitted to the bush 8 without loss, and the bush 8 can be prevented from being damaged by heat conduction. Further, since the torsion coil spring 9 is engaged with the flange 8A of the bush, mutual separation can be prevented.

Here, FIG. 4 shows an example in which the shaft runout preventing device of the spindle motor according to the present invention is applied to a disk reproducing device. However, the device of the present invention is applicable not only to the disk reproducing device but also to various electric appliances. It is. In the above example, the seat plate 3 for fixing the spindle motor 1 is formed as an individual component. However, instead of the seat plate 3 of this type, a machine frame of equipment can be used.

FIG. 5 schematically shows an example in which a chassis constituting a drive unit of a disk reproducing apparatus is used as a seat plate. In the figure, reference numeral 16 denotes a chassis, on which a pickup and other electronic and mechanical parts are mounted. Here, in this example, the chassis 16 is used as a seat plate, and locking portions 14, 14 for locking both ends of the torsion coil spring 9 are formed on the chassis. The chassis 16 is formed with a through hole 7 through which the drive shaft 2 of the spindle motor passes in addition to the locking portion 14, and the spindle motor 1 is fixed with the drive shaft 2 introduced from below the through hole. Then, a bush 8 is fitted to the drive shaft 2 as in the above example, and a torsion coil spring 9 mounted on the outer periphery thereof is provided.
The arms 9A, 9A at both ends are locked to the locking portions 14, 14. The locking portion 14 can be formed by bending a portion of the chassis 16 or the like. In this embodiment, the torsion coil spring 9 preferably uses a hook shape having both ends bent in a hook shape.

[0022]

As is apparent from the above description, according to the present invention, a bush fitted to the drive shaft of a spindle motor is used in place of the conventional swing type lever.
The installation does not take up space, and the installation space is sufficient within the mounting area of the spindle motor, which has been regarded as a dead space, so that it is not necessary to secure a new area. Therefore, by concentrating other parts around the spindle motor, it greatly contributes to downsizing of a disk reproducing apparatus and other electric equipment having the spindle motor as a driving source.

Also, since the torsion coil spring is also mounted on the outer periphery of the bush, it takes up little space for installation, and the restoring force of both ends urges the bush in the radial direction of the drive shaft of the spindle motor. The same effect of preventing shaft runout can be obtained.

Further, since the drive shaft of the spindle motor is brought into sliding contact with the bush, the torsion coil spring is not worn, so that a predetermined elasticity can be maintained for a long period of time. As a result, the elasticity of the torsion coil spring can be transmitted to the bush without loss, and the torsion coil spring is less likely to be detached from the bush.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a shaft runout prevention device for a spindle motor according to the present invention.

FIG. 2 is a plan view of the apparatus.

FIG. 3 is an enlarged plan view showing a main part of the apparatus of the present application.

FIG. 4 is a schematic diagram showing a part of a disk reproducing apparatus using the apparatus of the present invention.

FIG. 5 is an enlarged view of a main part showing another embodiment of the apparatus of the present invention.

FIG. 6 is a schematic plan view showing a shaft runout prevention device of a conventional spindle motor.

[Explanation of symbols]

 Reference Signs List 1 spindle motor 2 drive shaft 3 seat plate 8 bush 8A flange 9 torsion coil spring 9A arm 9B coil 14 locking part

Claims (2)

[Claims] A bush slidably fitted to a drive shaft of a spindle motor; a torsion coil spring provided on an outer periphery of the bush; and a torsion coil spring formed on a seat plate for fixing the spindle motor. A shaft motor run-out preventing device having a locking portion for locking both ends, wherein the bush is urged in the radial direction of the drive shaft by the elastic force of the torsion coil spring. 2. A bush having one end formed with a flange.
3. The shaft runout prevention device for a spindle motor according to item 1.