JPH08278462A - Driving device for rotary polygon mirror - Google Patents

Abstract

PURPOSE: To provide a rotary polygon mirror driving device used in an LBP (laser beam printer) where excellent rotational accuracy is realized, whose life is prolonged and which is thinned at low cost by eliminating the deterioration in rotational accuracy and the life of a bearing caused by heat generation. CONSTITUTION: This device is provided with a rotor 11 which is provided with a rotation axis 1 and a rotor magnet 4 and where a rotary polygon mirror 10 is fixed, and a stator 12 constituted of a stator coil 9 opposed to the rotor magnet 4 and generating electromagnetic torque and an iron stator base plate 6 where the bearing 7 journaling the rotation axis 1 is fixed. Then, the external shape of the base plate 6 is projected to the outside from the circumscribed circle of the polygon mirror 10 and the bearing 7 is fixed on the base plate 6 directly or through a member excellent in heat conductivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary polygon mirror driving device used for laser scanning in a laser beam printer (hereinafter abbreviated as LBP) or the like.

[0002]

2. Description of the Related Art In recent years, with the spread of LBP, rotary polygon mirror driving devices have been required to be smaller and thinner and to have lower cost. Under such circumstances, instead of the conventional bracket such as aluminum die casting, for example, the bearing is fixed to a resin-molded bracket or the like to achieve a thinner and lower cost. However, rotation fluctuation (hereinafter referred to as jitter)
It is necessary to maintain high-precision performance with respect to noise, noise, and tilt of the polygon mirror. In addition, in order to achieve high precision, measures such as applying a fluid bearing to the bearing have been taken, and at the same time, the life has been extended.

A conventional rotary polygon mirror driving device will be described below with reference to the drawings. In FIG. 4, reference numeral 1 denotes a rotary shaft, and a rotary polygon mirror 10 and a rotor boss 2 to which a rotor magnet 4 and a rotor frame 3 are fixed are fixed by a method such as shrink fitting to form a rotor 11. A bracket 5 having a mounting portion for a rotary polygon mirror driving device is a stator in which a stator core 8 in which a rotor magnet 4 and a magnetic material forming a magnetic path are laminated is provided with a stator coil 9 facing the rotor magnet 4 and generating an electromagnetic torque. Winding 1
3, a stator 12 including a stator substrate 6 on which a driving IC 15 is mounted, and a ball bearing 7 that supports the rotating shaft 1 are fixed.

The operation of the rotary polygon mirror driving device configured as described above will be described. First, when a current is supplied to the stator coil 9, an electromagnetic force is generated between the stator coil 9 and the rotor magnet 4, and the rotor 11 rotates about the rotating shaft 1 that is rotatably supported by the ball bearing 7.
Polarization scanning of the laser irradiated by the rotary polygon mirror 10 fixed to is performed.

[0005]

However, in the above-mentioned conventional configuration, (1) since the stator substrate 6 is present between the rotor 5 and the bracket 5 fixing the bearing, the wind cooling effect by the rotation of the rotor 11 is obtained. Is insufficient for the bracket, there is almost no bearing cooling effect, and improvement of bearing life is not required. (2) When the stator substrate 6 is made of a resin fiber such as paper phenol having a poor thermal conductivity, the effect of radiating the heat generated by the driving IC is insufficient and the margin for the specifications of the driving IC 15 is reduced. (3) In order to obtain the cooling effect of the bearing and the drive IC 15, when the stator substrate 6 is made of an iron substrate having a good thermal conductivity and the bracket 5 is made of aluminum die cast having a good thermal conductivity, the material cost is high. become. Had the problem.

The present invention solves the above-mentioned conventional problems, and provides a rotary polygon mirror driving device which realizes a long life of a bearing, does not deteriorate the performance of a driving IC, and is low in cost and thin. The purpose is to do.

[0007]

In order to achieve this object, a rotor having a rotary shaft and a rotor magnet according to the present invention, to which a rotary polygon mirror is fixed, and a stator facing the rotor magnet and generating an electromagnetic torque. It has a stator composed of an iron-based stator substrate to which a bearing supporting the winding and the rotating shaft is fixed, and the outer shape of the stator substrate protrudes outside the circumscribed circle of the rotary polygon mirror, and the bearing is It has a structure of being directly fixed to the stator substrate or being fixed via a member having a high thermal conductivity.

[0008]

With this configuration, the heat generated by the drive IC and the heat generated by the bearing can be radiated by the stator substrate when the rotary polygon mirror driving device is operated, and the stator is cooled by the wind cooling effect by the rotation of the rotor. As a result, it is possible to improve the life of the bearing, reduce the performance of the drive IC, and reduce the thickness at a low cost.

[0009]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a rotary shaft, and a rotary polygon mirror 1 is provided.
0, the rotor magnet 4, and the rotor frame 3 are fixed to each other, and the rotor boss 2 is fixed to the rotor 11 by a method such as shrink fitting. The stator substrate 6 having the mounting portion of the rotary polygon mirror driving device is an iron substrate or the like having a good thermal conductivity, and a stator core 8 in which a rotor magnet 4 and a magnetic material forming a magnetic path are laminated is provided so as to face the rotor magnet 4 and electromagnetically. A stator winding 13 provided with a stator coil 9 that generates torque and a drive IC 15 that operates a rotary polygon mirror drive device are mounted to form a stator 12. A herringbone groove is formed in the inner diameter of the bearing 7, which constitutes a fluid bearing and rotatably supports the rotary shaft 1. At this time, the bearing 7 is directly crimped onto the stator substrate 6.

The operation of the rotary polygon mirror driving device configured as described above will be described. First, when a current is supplied to the stator coil 9, an electromagnetic force is generated between the stator coil 9 and the rotor magnet 4, and the rotating shaft 1 that is rotatably supported by the bearing 7.
Rotation of the rotor 11 around the center of the laser causes the rotating polygon mirror 10 fixed to the rotor 11 to perform polarization scanning of the laser emitted. At this time, the wind generated by the rotary polygon mirror 10 hits the upper surface of the stator substrate 6.

As described above, according to the first embodiment, the heat of the drive IC 15 generated by the operation of the rotary polygon mirror drive device has a high heat conductivity because the drive IC 15 is directly mounted on the stator substrate 6. The heat of the bearing 7 generated by the rotation of the rotor 11 can be radiated to the substrate 6, and the heat of the bearing 7 can be radiated to the stator substrate 6 having a high thermal conductivity because the heat is directly caulked to the stator substrate 6, and the rotor can rotate. By cooling the stator substrate 6 by the air-cooling effect due to, the bearing 7 and the drive IC 15 can be cooled, the life of the bearing can be extended, and the deterioration of the performance of the drive IC 15 can be prevented.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the bearing 7 is directly fixed to the burring 6a of the stator substrate 6.

At this time, the contact area between the bearing 7 and the stator substrate 6 is increased, so that the thermal conductivity is increased, and the machine such as the perpendicularity of the bearing 7 with respect to the stator substrate 6 having the mounting portion of the rotary polygon mirror driving device. The accuracy or rigidity is increased, and not only the cooling effect but also the rotation accuracy of the rotary polygon mirror driving device can be improved.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, the bearing 7 is directly fixed to the collar 14 which is directly fixed to the stator substrate 6 and is made of a member having a high thermal conductivity.

At this time, since the shape of the bearing 7 is simplified as compared with the first embodiment, the heat radiation effect can be freely adjusted by operating the shape of the collar 14 while reducing the cost.

Although the bearing 7 is a hydrodynamic bearing in the first, second, and third embodiments, the same effect can be obtained even when the bearing 7 is an oil-impregnated metal.

[0020]

As described above, according to the present invention, a rotor having a rotary shaft and a rotor magnet, to which a rotary polygon mirror is fixed, a stator winding facing the rotor magnet and generating an electromagnetic torque, and a rotary shaft. It has a stator composed of an iron-based stator substrate to which a bearing that supports the shaft is fixed, and the outer shape of the stator substrate protrudes outside the circumscribed circle of the rotary polygon mirror, and the bearing is directly fixed to the stator substrate. The heat generated by the bearing is generated by the air-cooling effect of the rotary polygon mirror during the operation of the rotary polygon mirror driving device by implementing a configuration in which the rotary polygon mirror is driven or fixed via a member having excellent thermal conductivity. This allows heat to be dissipated, which makes it possible to improve bearing performance. At the same time, the heat generated by the drive IC can also be radiated, and the deterioration of the performance of the drive IC can be prevented. (2) The cost can be reduced by reducing the number of constituent members. (3) By directly fixing the bearing to the stator substrate,
It is possible to improve the mechanical accuracy such as the perpendicularity of the bearing with respect to the stator substrate having the mounting portion of the rotary polygon mirror driving device, or the rigidity, so that the rotary accuracy of the rotary polygon mirror driving device can be improved. It is possible to realize an excellent rotary polygon mirror driving device.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotary polygon mirror driving device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a bearing fixing portion of a rotary polygon mirror driving device according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a bearing fixing portion of a rotary polygon mirror driving device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a conventional rotary polygon mirror driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 2 rotor boss 3 rotor frame 4 rotor magnet 5 bracket 6 stator substrate 6a burring portion 7 bearing 8 stator core 9 stator coil 10 rotating polygon mirror 11 rotor 12 stator 13 stator winding 14 color

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Saiaki Matsumoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (14)

[Claims] 1. A rotor having a rotating shaft and a rotor magnet, to which a rotating polygon mirror is fixed, a stator having a stator winding facing the rotor magnet and generating electromagnetic torque, and a bearing supporting the rotating shaft. And an iron substrate to which the bearing is fixed, and the bearing is directly fixed to the iron substrate. 2. The rotary polygon mirror driving device according to claim 1, wherein the bearing is a hydrodynamic bearing having a herringbone groove for generating a dynamic pressure on either the rotating shaft or the sleeve. 3. The rotary polygon mirror driving device according to claim 1, wherein the bearing is an oil-containing metal. 4. The rotary polygon mirror driving device according to claim 1, 2 or 3, wherein the bearing is directly fixed to the iron substrate by crimping. 5. The rotary polygon mirror driving apparatus according to claim 1, wherein the bearing is directly fixed to a member having a high thermal conductivity fixed to an iron substrate. 6. The rotary polygon mirror driving device according to claim 1, wherein the bearing is burred on an iron substrate and is directly fixed to the burring portion. 7. The iron substrate is mounted with a drive IC for driving a rotary polygon mirror drive device, claim 1, claim 2, claim 3, claim 4, claim 5, or claim 6. Rotary polygon mirror drive device. 8. A rotor having a rotary shaft and a rotor magnet, to which a rotary polygon mirror is fixed, a stator having a stator winding facing the rotor magnet and generating electromagnetic torque, the stator and the rotary shaft. A rotary polygon mirror driving device having an iron substrate to which a bearing to be supported is fixed, the outer shape of the iron substrate protruding outside the circumscribed circle of the rotary polygon mirror, and the bearing being directly fixed to the iron substrate. 9. A rotary polygon mirror driving apparatus according to claim 8, wherein the bearing is a hydrodynamic bearing having a herringbone groove for generating a dynamic pressure on either the rotary shaft or the sleeve. 10. The rotary polygon mirror driving device according to claim 8, wherein the bearing is an oil-impregnated metal. 11. The rotary polygon mirror driving device according to claim 8, 9 or 10, wherein the bearing is directly fixed to the iron substrate by crimping. 12. The rotary polygon mirror driving device according to claim 8, wherein the bearing is directly fixed to a member having a high thermal conductivity fixed to an iron substrate. 13. The rotary polygon mirror driving device according to claim 8, wherein the bearing is subjected to burring processing on an iron substrate and is directly fixed to the burring portion. 14. A drive IC for driving a rotary polygon mirror drive device is mounted on an iron substrate, as claimed in claim 8, claim 9, claim 10, claim 11, claim 12, or claim 13. Rotary polygon mirror drive device.