JP2003061284A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize the optimum magnetization and shape structure of a magnet for rotary drive of a spindle motor capable of uniform torque correction. SOLUTION: A spindle motor consists of a stator 4 where a board supported by a bearing 5 for a motor shaft 1 is provided with a plurality of coils 9 in circumferential direction to the above bearing and that at equal angles, and a rotor 10 in which the above motor shaft is press-fitted and fixed, and which is born turnably by the above bearing, and has a rotor yoke 16 being provided with several magnets 13 for rotary drive in opposition to the above plural coils. Each of the above magnets for rotary drive is made oblong, and even number of pieces are provided at equal angles in the above circumferential direction.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a spindle motor capable of uniform torque correction, and more particularly, to a shape structure of a rotation driving magnet of a flat disk facing spindle motor for a flexible disk. It is about. 2. Description of the Related Art A conventional technique of a 1/2 inch height flexible disk spindle motor will be described below with reference to FIGS. 8 is a half sectional view of a stator of a flexible disk spindle motor, and FIG. 9 is a half sectional view of a flexible disk spindle motor. 4 and 5 are views showing a magnetized state of a rotary driving magnet surface of a conventional rotor, and FIG. 6 is a perspective view of a flexible disk spindle motor. In FIG. 9, a rotor 10A comprises a rotor yoke 16, a resin frequency generator (hereinafter referred to as FG) magnet 12, a disk positioning clamp 20, and a motor shaft 1. The rotor yoke 16 is an iron plate made of a zinc steel plate. A resin FG magnet 12 for detecting a rotational speed is formed on an outer peripheral portion by outsert molding, and one circumference is magnetized to 60 poles. The FG patterns 7 shown in FIG. 2 are provided on the base plate substrate 2 at predetermined intervals. FIG. 5 shows a magnetic pole surface of the rotor 10A in a case where the entire circumference is magnetized and no non-magnetized portion is provided. 22.5 degrees). FIG. 7 (B) shows a back electromotive force waveform generated by the rotor in this case. The horizontal axis t indicates time, and the vertical axis V indicates the back electromotive force. The back electromotive force waveform of the rotor shown in FIG. 7 (B) is a waveform close to a rectangular wave, and therefore, the rotation of the rotor 10A may vibrate, or the torque ripple and wow / flutter may deteriorate. In order to improve this, as shown in FIG. 4, the rotation driving magnet 13B is magnetized to 16 poles (8 pole pairs),
In FIG. 4, substantially triangular non-magnetized portions 3B are provided at 16 positions on the outer peripheral portion to correct the torque ripple. By providing the non-magnetized portion 3B on the outer peripheral portion, the back electromotive force waveform is corrected, and the torque ripple and wow /
Flutter has been improved. FIG. 7A shows a back electromotive force waveform generated by the rotor at this time, where the horizontal axis t represents time,
The vertical axis V indicates the back electromotive force. The back electromotive force waveform shown in FIG. 7A is closer to a sine wave (sine wave) than the back electromotive force waveform of FIG. 7B without the non-magnetized portion. I understand. Therefore, by providing the non-magnetized portion 3B on the outer peripheral portion, the back electromotive force waveform is made to be a waveform close to a sine wave (sine wave), so that vibration due to rotation of the rotor 10A, torque ripple, wow / I am improving flutter. In FIG. 8 and FIG. 9, a stator 4A comprises a sintered oil-impregnated bearing 5, a metal base printed board 2A and a plurality of coils 9A. The metal base printed board 2A includes a rotor position detecting Hall element 11 and electronic components. 6 are arranged. The plurality of coils 9A are flat coils, and nine of them are adhesively fixed to the metal base printed circuit board 2A. The lower end of the sintered oil-impregnated bearing 5 is held by caulking on the metal base printed circuit board 2A. When the rotor 10A in which the motor shaft 1 is pressed into the rotor yoke 16 is mounted on the sintered oil-impregnated bearing 5, the rotor 10A is brought into contact with the sintered oil-impregnated bearing 5 by magnetic attraction of the metal base printed board 2A of the stator 4A of the ring-shaped rotary drive magnet 13A. It is rotatably held by a thrust ball bearing 14. The rotor 10A rotates about the motor shaft 1 by a three-phase drive current applied to the plurality of coils 9A. The rotation speed is 300r / min or 360r /
min. In FIGS. 6 and 9, a drive pin 2 for driving a disk (not shown) is provided above the rotor yoke 16.
The clamp magnet 20 magnetized to 8 or 16 poles in the radial direction with the arm 17, the sheet 18, and the arm 17 is formed by outsert molding. A drive pin 21 is provided at one end of the arm 17, and a rotation fulcrum 19 is provided at an intermediate portion. As a result, the disk is fixed at the position regulated by the drive pin 21 and rotates together with the rotor 10A. [0013] The rotation driving magnet of the conventional spindle motor for a flexible disk is ring-shaped, and the rotation of the rotor shown in FIG. 4 is reduced in order to reduce torque ripple and wow / flutter during rotation. A non-magnetized portion 3B is provided on the magnetic surface. However, for this reason, the magnet of the unnecessary non-magnetized portion is also mounted. Further, in the non-magnetized portion 3B, the magnet material becomes non-uniform or the magnetization varies, and a sufficient non-magnetized portion 3B cannot be formed. Therefore, it is difficult to optimize the coil drive waveform. For this reason, the conventional spindle motor cannot perform a sufficient torque correction, and the torque ripple and wow / flutter are not reduced so that noise and vibration are large, and the magnetizing voltage must be corrected and the magnetizing coil must be adjusted. Had occurred. In addition, since rare earth magnets are expensive, there has been a strong demand for finding a configuration such as a shape arrangement of magnets that can bring out high performance with as little magnet material as possible. In view of the above, the present invention has been made in view of the above-mentioned problems. In particular, the rotary drive magnets are each provided with an even number of the rotary drive magnets at an equal angle in the circumferential direction while each of the rotary drive magnets has a rectangular shape. It is an object of the present invention to provide a spindle motor capable of performing uniform torque correction with uniform and uniform performance, without causing uneven magnetization of a non-magnetized portion and variation in magnet composition. . [0016] In order to solve the above-mentioned problems, the invention described in claim 1 provides a plurality of coils 9 on a substrate 2 held by a bearing 5 for a motor shaft 1. A stator 4 provided circumferentially with respect to the bearing and at an equal angle;
A rotor 10 having a rotor yoke 16 in which the motor shaft is press-fitted and fixed, rotatably supported by the bearing, and provided with a rotation driving magnet 13 opposed to the plurality of coils, respectively. The present invention provides a spindle motor in which each of the rotation driving magnets 13 has a rectangular shape, and an even number of the rotation driving magnets 13 are provided at an equal angle in the circumferential direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a spindle motor according to the present invention will be described below with reference to FIGS. 1 to 3, FIG. 6, and FIG. 1/2 of the present invention
FIGS. 1 to 3, 6 and 7 show an embodiment of a spindle motor for inch-height flexible disks.
This will be described below in order. 1 is a view of a rotor of a spindle motor according to the present invention viewed from a magnetized surface, FIG. 2 is a stator view, FIG. 3 is a half sectional view, and FIG. 6 is a perspective view. One embodiment of the spindle motor of the present invention is as follows.
Motor shaft 1, metal base printed board 2, non-magnetized part 3,
Sintered oil-impregnated bearing 5, electronic component 6, FG pattern 7, non-magnet portion 8, multiple coils 9, Hall element (magnetic sensor) 11, FG magnet 12, rotation driving magnet 13, thrust ball bearing 14, rotor yoke 16, arm 17, a seat 18, a pivot 19, a clamp magnet 20, and a drive pin 21. The spindle motor for a flexible disk shown in FIG. 1 comprises a rotor and a stator. In FIG. 1, a rotor 10 is made up of a rotor yoke 16 made of a zinc steel plate, and a resin FG magnet 12 for detecting a rotational speed is formed on an outer peripheral portion by outsert molding, and is magnetized to 60 poles per circumference. Inside, 16 plate-shaped rectangular rare earth Ne—Fe—B based sintered magnets constituting the rotary driving magnets 13 corresponding to the plurality of coils 9 are bonded and fixed, and adjacent magnets are formed. Are magnetized to 16 poles (8 pole pairs) with opposite polarities. The rotation driving magnet 13 is composed of an even number (sixteen) of rectangular (strip-shaped) magnets for each pole, radially extending on the circumference of the rotor yoke 16 centering on the axis 1 by 22.5. The plurality of coils 9 are adhered and fixed at equal angles in degrees. The rotary drive magnet 13 shown in FIG.
Are formed between the magnets of the opposite polarities, there are a total of 16 non-magnet portions 8 having no substantially triangular magnet. The non-magnet portion 8 is a non-magnetized portion. FIG. 3 is a half sectional structural view of a spindle motor for a flexible disk. The stator 4 includes a metal base printed board 2, a plurality of coils 9 provided on the upper surface of the metal base printed board 2, and a metal base printed board. It comprises a sintered oil-impregnated bearing 5 fixed to a printed circuit board 2, on which a Hall element 11 for rotor position detection and an electronic component 6 are also arranged. The plurality of coils 9 are flat-plate coils, and nine of them are bonded and fixed to the metal base printed board 2. The sintered oil-impregnated bearing 5 is interposed with the lower end held by caulking on the metal base printed board 2. When the rotor 10 having the motor shaft 1 pressed into the rotor yoke 16 is mounted on the sintered oil-impregnated bearing 5, the rotor 10
Is rotatably held by the sintered oil-impregnated bearing 5 and the thrust ball bearing 14 by magnetic attraction of the drive magnet 13 with the metal base printed board 2 of the stator 4. The rotor 10 is rotatable with respect to the stator 4 by the thrust ball bearing 14 and the sintered bearing 5. The rotor 10 is centered on the shaft 1 by the well-known principle of rotation of a brushless motor by the interaction of a field magnetic field of a rotation driving magnet 13, a current applied to a plurality of coils 9, a Hall element, and a brushless motor driving circuit (not shown). Rotate as Its rotation speed is 300 r / min or 360 r / m
in. 3 and 6, the rotor yoke 1
On the upper side of 6, a drive pin 21 for driving a disk (not shown), an arm 17, a sheet 18, and a clamp magnet 20 magnetized to 8 or 16 poles in the radial direction are formed by outsert molding. . A drive pin 21 is provided at one end of the arm 17 and a pivot 19 is provided at an intermediate portion. As a result, the disk is fixed at the position regulated by the drive pin 21 and rotates together with the rotor 10. The spindle motor comprises:
An even number of rotary drive magnets 13 having a rectangular shape for each pole
The weight of the magnet is about 60% of that of the conventional spindle motor, so that the amount of expensive rare earth magnet used can be greatly reduced and the cost can be reduced accordingly. FIG. 7C shows a back electromotive force waveform generated by the rotor of the spindle motor of the present invention shown in FIG. 1. The horizontal axis t indicates time, and the vertical axis V indicates the back electromotive force. The back electromotive force waveform by the rotor of the spindle motor of the present invention shown in FIG. 7 (C) is a sine wave (sine wave) compared to the back electromotive force waveform when the non-magnetized portion 3B of FIG. 7 (A) is provided. It can be seen that the waveform is closer to (). Therefore, torque ripple correction can be performed, and vibration noise is reduced and a low torque ripple performance can be obtained as compared with the conventional one. As described above, according to the spindle motor of the present invention, a plurality of coils are provided on a substrate held by a motor shaft bearing in a circumferential direction with respect to the bearing.
A stator having an equiangular angle and a rotor having a rotor yoke which is press-fitted and fixed to the motor shaft, is rotatably supported by the bearing, and is provided with a rotation driving magnet opposed to the plurality of coils. In the spindle motor, each of the rotation driving magnets is formed in a rectangular shape and an even number of the rotation driving magnets are provided at an equal angle in the circumferential direction, so that the performance of the magnets can be uniform and uniform. For this reason, according to the spindle motor of the present invention, the rotor does not have uneven magnetization in the non-magnetized portion or variation in the composition of the magnet, so that uniform torque correction can be performed. Further, according to the spindle motor of the present invention, the configuration of the rotary driving magnet is simpler and simpler than that of the conventional magnet having a non-magnetized portion on the outer peripheral portion. Can also be magnetized at equal intervals at equal angular division angles, and the manufacturing efficiency of the rotary drive magnet can be improved. Further, according to the spindle motor of the present invention, the rotary drive magnets are formed by forming each of the rotary drive magnets in a rectangular shape and providing an even number of the same at the same angle in the circumferential direction. The weight of the rotary driving magnet is about 60% of the conventional one, so that the amount of expensive rare earth magnet used can be greatly reduced, and the cost can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a magnetized surface on a bottom surface of an embodiment of a rotor in which rectangular divided magnets of a spindle motor according to the present invention are radially arranged at equal angles. FIG. 2 is a view showing a stator of one embodiment of the spindle motor of the present invention. FIG. 3 is a diagram showing a half cross-sectional structure of an embodiment of the spindle motor of the present invention. FIG. 4 is a diagram showing a magnetized surface of a rotor as an example of a conventional spindle motor. FIG. 5 is a diagram showing a magnetized surface of an example of a conventional spindle motor without torque correction. FIG. 6 is a perspective view of the present invention and a conventional spindle motor. FIG. 7 is a diagram showing a back electromotive force waveform by the rotor of the spindle motor of the present invention and a conventional spindle motor, respectively. FIG. 8 is a diagram showing a stator of an example of a conventional spindle motor. FIG. 9 is a diagram showing a half-section structure of an example of a conventional spindle motor. [Description of Signs] 1 Motor shaft 2 Metal base printed board 3 Non-magnetized part 4 Stator 5 Sintered oil-impregnated bearing 6 Electronic component 7 FG pattern 8 Non-magnet part 9 Plural coils 10 Rotor 11 Hall element 12 FG magnet 13 Rotation drive Magnet 14 thrust ball bearing 16 rotor yoke 17 arm 18 seat 19 rotation fulcrum 20 clamp magnet 21 drive pin

Claims (1)

Claims: 1. A stator having a plurality of coils provided on a substrate held by a bearing for a motor shaft in a circumferential direction and at an equal angle with respect to the bearing; A spindle motor which is press-fitted and fixed, is rotatably supported by the bearing, and has a rotor yoke provided with a rotation driving magnet opposed to the plurality of coils, respectively. A spindle motor having a rectangular shape and an even number provided at an equal angle in the circumferential direction.