JPH01177852A - Spindle motor - Google Patents

Abstract

PURPOSE:To reduce in size a bearing mechanism and to reduce its loss by applying a prepressure to a bearing by means of a magnetic attraction force, and energizing the inner race of the bearing in a thrust direction by an elastic member. CONSTITUTION:An FG substrate 15 for forming a frequency generator (FG) and an FG magnet 14 are so disposed oppositely at rotor and stator sides as to generate a magnetic attraction force therebetween thereby to apply a prepressure to a ball bearing 3 by the magnetic attraction force of the magnet 14 with a soft magnetic plate provided on the substrate 15. An axial energizing force is applied to the bearing 3 by an elastic member 13 to provide rigidity in a thrust direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a spindle motor having a structure in which a sliding bearing is used to support a rotor portion.

[Prior art]

A spindle motor is generally used as a drive source for chucking and rotating the center of rotation of a disk-shaped recording medium such as a magnetic sheet. This type of spindle motor uses a frequency generator (Frequency Generr).
ator (hereinafter referred to as FG), and is configured to apply speed control based on the signal output from this FG to keep the set rotational speed stable.

FIG. 3 is a front sectional view showing the configuration of a conventional spindle motor used, for example, in an electronic camera.

In FIG. 3, 50 is the base of the spindle motor, 51 is a shaft whose one end is press-fitted into the base 50,
52 is a ball bearing fitted to the other end of the shaft 51;
Reference numeral 53 denotes a cap that is fixed to the shaft 51 by press-fitting or adhesive, and applies preload to the ball bearing 52.

55 has a pair of ball bearings 52 fixed to the inner periphery by press-fitting or adhesive, and a hub of the media to be rotated (
56 is a chucking magnet provided in a concave surface provided on the other end surface of the spindle 55 to magnetically attract the hub; 57 is press-fitted into the spindle 55 or adhesively attached. The rotor yoke is fixed using means and is constructed using a soft magnetic material.

Reference numeral 58 denotes a main magnet for a field that is attached to the rotor yoke 57, 59 a drive coil that is installed on the base side facing the main magnet 58, 60 a drive coil 59 fixed to one side by gluing or soldering, and others. This is a stator substrate on which a Hall element 61 is fixed by soldering.

A sub-rotor yoke 62 is disposed opposite to the stator substrate 60 and is also disposed at one end of the spindle 55. A sub-rotor yoke 63 is attached to the sub-rotor yoke 55, and is magnetized with multiple poles at equal pitches in the circumferential direction of its outer peripheral surface. A frequency generation magnet (hereinafter referred to as an FG magnet) 64 is a frequency generation substrate (hereinafter referred to as an FC substrate) disposed opposite to the FC magnet 63 and fixed to the base 50 with adhesive.

In the above configuration, when a drive voltage with a predetermined phase difference is applied to the drive coil 59 by a drive circuit (not shown), the main magnet 58 obtains a repulsive force against the resulting magnetic field, and the rotor yoke 58 is attached to the drive coil 59. Rotate with objects. As the FC magnet 63 rotates together with the rotor yoke 58, a signal corresponding to the rotational speed of the rotor is detected from the FG board 64.

However, since the conventional spindle motor shown in FIG. 3 uses a ball bearing 52 to support the rotor, it is difficult to downsize the motor and the product cost increases.

In addition, when using sintered metal, it is necessary to shift it to one side in the thrust direction, and a method is used in which main magnets are arranged opposite to the stator board and the attraction force is used to shift it to one side, but iron loss is large. In addition, due to the large suction force, it was not possible to use small bearings, so large bearings had to be used, and as a result, the motor could not be made smaller.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a small, low-cost, double rotor type spindle motor that can solve the problems of the prior art, has a bearing made of sintered metal and a bearing, and has a bearing made of sintered metal and a bearing.

[Means to achieve the purpose]

The present invention applies preload to the ball bearing by arranging the FC board constituting the FG and the FC magnet facing each other on the rotor side and the stator side so that a magnetic attraction force is generated between them. The above object is achieved by a structure in which the bearing is given rigidity in the thrust direction by applying an axial biasing force to the bearing using the member.

〔Example〕

The present invention will be specifically explained below with reference to FIG.

In FIG. 1, 1 is a chassis, 2 is a shaft with one end press-fitted into the chassis and the other end threaded, and 3 is a center hub of a recording medium (not shown) that is fitted onto the outside of the shaft 2 and whose outer ring is a center hub for a recording medium (not shown). 4 is a cap with a female thread formed on the inner periphery to guide the center hub, 4 is a chucking magnet, and 6 is a soft magnetic magnet, which will be described later, by its outer ring 6a. A spindle that positions the plate and fixes a part of the outer ring of the bearing 3 on the inner periphery by press fitting or adhesive, 7 is a rotor yoke fixed to the spindle 6 by adhesive, 8 is a main for the motor field bonded to the rotor cork 7. The magnet 9 is a flexible wiring board in which a motor drive coil is integrally formed. Reference numeral 10 denotes a backing substrate attached to the flexible wiring board 9 as a reinforcing material.

11 is a sub-rotor yoke for collecting the magnetic flux generated by the main magnet 8; 12 is a sintered oil-impregnated metal that is press-fitted into the inner peripheral surface of the spindle 6 and fitted externally to the shaft 2; and 13 is a shaft fixed to the bearing 3 at one end. engages the side,
An elastic member 14 whose other end engages with the stepped portion of the shaft 2 to generate rigidity in the thrust direction is fitted around the outer periphery of the spindle 6, is attracted to the rotor yoke 7, and is multi-pole magnetized radially and at equal pitches. This is a FG magnet.

15 is provided facing the FG magnet 14, is printed with the same number of FG generator patterns as the number of poles of the FC magnet 14, and is made of a soft magnetic plate such as a silicon steel plate.
The G board 16 is an elastic member made of a material such as rubber and interposed between the FG board 15 and the FG stud 17 integrally formed on the chassis 1.

Next, the operation of the spindle motor with the above configuration will be explained.

A chucking magnet 5, a rotor yoke 7, a main magnet 8, a sub-rotor yoke 11, and an FC magnet 14, which are integrated into a spindle 6 supported by a bearing 3, are formed on a flexible wiring board 9 and are connected to a drive voltage. Rotates by being fed. It is necessary to apply preload to the bearing 3 in order to prevent it from wobbling during the rotation of the rotor. A preload is applied to the bearing 3 by biasing the spindle 6 downward in FIG. This can be realized by appropriately setting the gap between the FC board 14 and the FC board 15.

In addition, in the embodiment shown in Fig. 1, the spindle surface height (
In other words, the height of the outer ring portion 6a from a reference position (not shown)
By rotating the cap 4, the shaft 2 is moved up and down so that the bearing 3 resists or enhances the biasing force of the elastic body 13, and the height of the spindle surface is adjusted to ±, for example.
It is configured so that it can be adjusted to a desired height within an adjustment height of 5 μm.

FIG. 2 is a front sectional view showing another embodiment of the invention.

The same reference numerals have been used for the same parts as in FIG. 1, so redundant explanations will be omitted. An elastic member 21 for giving thrust rigidity to the motor is fitted on the outside, and an E-ring 22 as a positioning member for regulating the position of the elastic member 21 is fitted on the shaft 20. The feature is that a sintered oil-impregnated metal 23 is fitted into the part.

According to the embodiment shown in FIG. 2, since the sintered oil-impregnated metal 23 is used as the support member, the cost can be reduced compared to the embodiment shown in FIG. 1, and the bearing fitting part and the metal fitting part are coaxial. As the rotational speed can be improved, high rotational accuracy can be obtained.

〔effect〕

As is clear from the above description (according to the present invention, the magnetic attraction force between the FG magnet and the soft magnetic plate provided on the FG board is used to apply a preload to the bearing, and the rigidity in the thrust direction is adjusted to the inner ring of the bearing). Since this is performed by biasing with an elastic member, the bearing mechanism can be made small, and a small double rotor type spindle motor with low loss can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention, FIG. 2 is a front sectional view showing another embodiment of the invention, and FIG. 3 is a front sectional view showing the configuration of a conventional spindle motor. 1・・・−・−Chassis, 2.20−・−−−m−
・-shaft, 3-...-bearing, 5-・
−・−・・−Chucking magnet, 6−・−・−・
−・−Spindle, 7・−・・・・−・・Rotor yoke, 8−−−−・−Main magnet, 9・−−−
---------Flexible wiring board, 11---------
-...-Sub rotor, 12.23-...--Sintered oil-impregnated metal, 13.21-------Elastic member, 14---1----... FG stud, 15-・
-・-・-FG board. Agent Patent Attorney Yasutake Ooto

Claims (3)

[Claims] (1) In a spindle motor that is equipped with a frequency generator that rotates a disc-shaped recording medium attached to a spindle integrated into the rotor and generates a signal according to the rotation of the rotor, it is fixed on the stator side. a ball bearing and a sliding bearing supported by the shaft and fixed to the spindle; an elastic member fitted onto the shaft with one axial end in contact with one end of the bearing; The frequency generating circuit includes a frequency generating magnet disposed in the circumferential direction of the spindle, and a frequency generating substrate for detecting a frequency signal by disposing a magnetic material on the stator side facing the magnet, and detecting the frequency signal. A spindle motor characterized in that a pressing force obtained by magnetic action between a magnet and a substrate is applied to the bearing as a preload. (2) The spindle motor according to claim 1, wherein the position of the elastic member is restricted by a step provided in the longitudinal direction of the outer circumference of the shaft. (3) The spindle motor according to claim 1, wherein the position of the elastic member is regulated by a positioning member that fits into an annular groove provided at a predetermined position on the outer periphery of the shaft.