JPS61262062A - Motor apparatus - Google Patents

Abstract

PURPOSE:To contrive not to need balance rings which have been conventionally needed, by forming a magnet with a resin member, and by forming a concave section for balance compensation at one end at least of the both ends of the magnet. CONSTITUTION:A motor apparatus M1 is provided with a motor case 2 for containing respective components, and with a rotary shaft 21 for organizing a rotary body supported pivotally by bearings 4, 4 arranged at the case 2 and the case cover 3 respectively. a resin magnet 22 is fitted and bonded on the shaft 21. On the both end surfaces of the magnet 22, weights are added to the balance compensation grooves 22a, 22b formed on molding the magnet, on balance adjustment, and the balance is adjusted. As the result, balance rings which have been conventionally needed are unnecessitated, and problematic points on bonding strength and exfoliation on bonded surfaces can be settled.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a motor device, and more particularly to a VTR.

The present invention relates to a motor device that is used in floppy disks, laser beam printers, etc. and requires high-precision rotation.

(B) Conventional Technology These days, motor devices are required to have high rotational accuracy, so the generation of vibration and noise is strictly limited. Therefore, it is natural to improve the precision of parts such as bearings in order to suppress the generation of such vibrations and noise, but it is necessary to improve the rotational imbalance that cannot be suppressed by the precision of these parts alone.
Conventionally, this was done as follows. For example, regarding the motor for driving the polygon mirror of a laser beam printer, as shown in Fig. 4,
The motor device 1 includes a motor case 2 that houses each component, and has a rotating shaft 5 that is rotatably supported by bearings 4.4 provided in the case 2 and the case M3, respectively. The shaft 5 fits and holds a magnet 6 made of a hard material such as barium ferrite or manganese aluminum, and has balance correction grooves 7a at both ends of the magnet 6.
Balance rings 7.7 each having a length of 7 m are fixed with an adhesive, and a flange 10 for holding a polygon mirror (light deflecting polygon mirror) 9 constituting a rotated body is fitted. A stator 11 is disposed inside the motor case 2 facing the magnet 6, and a Hall element 12 is further provided near the magnet 6 by a fixing member.
is fixed, the rotation speed and phase are detected by the element 12, and current is switched or supplied to each phase of the stator 11, and the rotating shaft 5 rotates while maintaining a predetermined rotation speed.

Adjustment of the rotation of the motor device with the above configuration is performed using a general-purpose balance correction 8! (not shown) supports two bearings to read the balance correction position, and adjusts by adding weights to the balance correction ll7a, 7a provided on the balance ring 7.7 located at both ends of the magnet 6. Two side corrections have been made.

&→ Problems to be Solved by the Invention By the way, since the conventional magnet 6 is made of a hard material such as sinterable barium ferrite or manganese aluminum, it is not possible to directly form grooves for balance correction. Because it is difficult or expensive, the above balance ring 7
was employed, and the ring 7.7 was fixed to the rotating shaft 5 with adhesive. However, since the ring 7 is thin and cannot have a large adhesive surface with the rotating shaft 5, a problem arises in adhesive strength. Especially centrifugal force or heat during high speed rotation? [Peeling of the adhesive surface when # is added is a big problem. Furthermore, the balance ring 7
．． 7 to the rotating shaft 5, a highly reliable anaerobic adhesive is generally used, but since the part of the adhesive that protrudes beyond the mating surface does not harden, it must be wiped off. The amount of adhesive is quite delicate; if it is too much, it will stick out, and if it is too little, the adhesive strength will decrease.

Therefore, there is a problem in that this work requires careful attention and the configuration of the balance ring 7.7 is not suitable for mass production.

4. Means for Solving the Problems The present invention aims to solve the above-mentioned problems, and includes forming a magnet from a resin member, and adjusting the balance at at least one of both ends of the magnet. The balance correction means is characterized by forming a recessed portion for the purpose.

(E) Operation By adopting the above-mentioned means, the rotational balance of the motor device can be adjusted by directly applying a weight to the balance correction groove provided in the magnet that is integrated with the rotating body, without using any member that may be separated. It is done in addition.

(f) Example Embodiments of the present invention will be described below with reference to the drawings.

(F-1) First Example First, the first example will be described based on FIG.

The motor device M is a motor case 2 that houses each component.
It has a rotating shaft 21 that constitutes a rotating body that is supported by bearings 4.4 provided on the case 2 and the case lid 3, respectively. A resin magnet (22) whose main component is nylon or the like is fitted and adhered to the shaft 21. Incidentally, since the fitting surface between the magnet 22 and the rotating shaft 21 is sufficiently wide, there is no need to apply adhesive over the entire fitting portion, and assembly is easier than in the past. Furthermore, balance correction grooves 2 are formed on both end surfaces of the magnet 22 during magnet molding.
2a and 22b are provided, and the balance correction groove 22
A and 22b are balanced by adding weights thereto during balance adjustment. Further, a flage 10 that holds a polygon mirror 9 constituting a rotated body is firmly fixed to the rotating shaft 21 by, for example, shrink fitting, and a stator is mounted inside the motor case 2 facing the magnet. 11 is disposed, and a Hall element 12 is fixed to a fixing member supported on the case 2 at a position facing the lower end of the magnet 22.

The magnet 22 of this embodiment is mainly composed of nylon, so it is easy to form balance correction grooves, and the resin magnet can produce a surface magnetic flux density of 1000 Gauss, which is equivalent to the conventional barium ferrite magnet. It has a certain degree of magnetic force.

Since this embodiment has the above-described configuration, the Hall element 12 detects the rotation speed and phase, switches and supplies current to each phase of the stator 11, and rotates the rotating shaft 21, which is integrated with the magnet 22. , further rotates the polygon mirror 9, which is an object to be rotated. Then, to adjust the rotation, a general-purpose balance corrector (not shown) supports the bearings 4.4 at two locations, reads the balance correction position, and inserts the balance correction grooves 22a and 22b directly provided in the magnet 22, respectively. Two-sided correction is performed by adding weights and adjusting. In addition,
In the embodiment, the magnet 22 is fitted and bonded to the rotating shaft 21, but the shaft 21 and the magnet 22 may be integrally molded.

(F-2) Second Embodiment Next, a second embodiment will be described based on FIG.

The motor device M2 includes a motor case 24 that covers and accommodates each component, and a shaft 27 is erected on a flange 26 fixed to the bottom of the case 24 so as to fix the lower end thereof. A sleeve 29 constituting a rotating body is rotatably fitted onto the shaft 27, and a polygon mirror 9 is fixed to the flange portion 29a of the sleeve. A resin magnet 31 having a balance correction groove 31a is fitted and bonded thereto. Note that since the mating surface between the sleeve 29 and the magnet 31 is sufficiently wide, there is no need to apply adhesive over the entire mating portion, and assembly is easier than before, as in the first embodiment. . Furthermore, the outer peripheral surface of the shaft 27 is provided with a spiral groove 27a and a herringbone FllJ27b.
A thrust plate 32 having a throttle hole 32a is fixed to the upper part of the sleeve 29 facing the upper end of the shaft 27, and a gas such as air is supplied from the lower end of the shaft 27. These grooves 27a, 27b, the inner wall of the sleeve 29, and the throttle hole 32a constitute a hydrodynamic gas bearing.

Since this embodiment has the above configuration, the sleeve 2
Since the magnet 9 and the magnet 31 that rotate together with the resin magnet 1- are used as in the previous embodiment, the balance correction groove 3
1a is easy to form, and the sleeve 29 rotates with high precision using a hydrodynamic gas bearing.

(F-3) Third Embodiment Next, a third embodiment will be explained based on FIG.

The motor device M3 includes a sleeve-like holder 33 having a flange at the bottom and the stator 11 fixedly attached to the outer periphery of the upper part.The holder 33 has a divided structure in which a groove in the shape of a herringbone is formed on the inner periphery. Bearings 34a and 34b are arranged above and below. Further, a steel ball 36 as a thrust receiver is disposed on a thrust plate 35 fixed in contact with the lower end of the holder 33, and the bearings 34a, 34
A rotatably rotating shaft 37 is supported by a radial dynamic pressure gas bearing consisting of a radial dynamic pressure gas bearing (b) and a steel ball 36 (a radial gas bearing consisting of a steel ball 36). Further, a flange 39 is fixed to the shaft 37, and a resin magnet 40 having a balance correction groove 40a is insert-molded inside the flange 39, and a polygon mirror 9 is mounted on the flange 39. is permanently installed. Inside the flange, the Hall element 12 is fixed to a fixing member supported by the holder 33 at a position opposite to the magnet 40.

Since this embodiment has the above configuration, the flange 3
Since the magnet 40 that rotates integrally with the shaft 37 via the shaft 37 is made of a resin magnet as in the first embodiment, it is easy to form the balance correction groove 40a, and the rotating body is rotated around the shaft by a hydrodynamic gas bearing. It is supported and rotates with high precision.

In the above embodiment, a groove for balance correction was formed in the resin magnet, but a weight for balance correction may be engaged instead of a groove, and in this case, the centrifugal force acting on the weight may be engaged. Of course, a recessed portion having opposing wall surfaces may be formed in the resin magnet.

(g) Effects As explained above, according to the present invention, a resin magnet in which recesses such as grooves for balance correction are easily formed is used.
In addition, since the recess for balance correction is formed directly on the magnet, the conventionally required balance ring is no longer necessary, and the problem of adhesive strength and peeling of the adhesive surface can be solved.
Similarly, gluing work, which was difficult in the past, is no longer necessary, and the assembly of the motor device becomes extremely easy, making mass production possible.

Furthermore, since a balance ring is not required, the number of parts can be reduced and the weight of the device can be reduced.

[Brief explanation of drawings]

1 is a sectional view of a motor device according to a first embodiment of the present invention, FIG. 2 is a sectional view of a motor device of a second embodiment, FIG. 3 is a sectional view of a motor device of a third embodiment, and , FIG. 4 is a sectional view of a conventional motor device. M,, M2. M, Motor device, 9 Rotated object (polygon mirror), 11 - Stator, 21
...Rotating body (rotating shaft), 22...Resin magnet
, 29.Rotating body (sleeve), 31..Resin magnet, 37..Rotating body (shaft), 40.Resin magnet, a, 22a122b. 31a, 40a, - Balance correction recess (balance correction groove).

Claims (2)

[Claims] (1) A rotating body is rotatably supported on a fixed member to which a stator is fixed, and a magnet is disposed on the rotating body facing the stator, and a rotated body that requires high rotational accuracy. What is claimed is: 1. A motor device in which the magnet is a resin magnet, and a balance correction recess is formed in the resin magnet. (2) The motor device according to claim 1, wherein the resin magnet is integrally molded with a rotating body.