JPH05303050A - Deflection scanner containing dynamic pressure fluid bearing - Google Patents

Abstract

PURPOSE:To miniaturize the deflection scanner containing the dynamic pressure fluid bearing, and also, to improve its accuracy by preventing heat from being accumulated in the inside. CONSTITUTION:A rotary shaft 31 is fitted to a sleeve 41 and constitutes a dynamic pressure fluid bearing, and a driving magnet 34 and a motor substrate 40 are opposed and constitute a driving motor. Also, in the outside periphery of the sleeve 41, a flange part 51 and an annular groove 52 are provided, and by allowing the lower face of the flange part 51 to abut on the inside surface of an optical box 53, and fitting and attaching an elastic member 54 to the annular groove 52, the sleeve 41 and the optical box 53 are fixed. Moreover, to the lower part of the sleeve 41, a radiating fin 55 is attached, and heat generated in the dynamic pressure fluid beating is emitted to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic fluid used for deflecting a laser beam in a laser beam printer, for example, by fixing a rotary device such as a rotary polygon mirror to a rotary shaft supported by a hydrodynamic bearing. The present invention relates to a deflection scanning device including a bearing.

[0002]

2. Description of the Related Art In recent years, as a rotating device is required to rotate at a high speed and with high precision, in a laser beam printer or the like, a hydrodynamic bearing which rotates in a non-contact manner in order to obtain high precision rotation. Is used.

FIG. 5 is a sectional view of a deflection scanning device using such a hydrodynamic bearing, in which a rotary shaft 1 is rotatably fitted to a sleeve 2 and the outer peripheral surface of the rotary shaft 1 has a herringbone shape. The shallow groove 3 is engraved to form a dynamic pressure radial bearing,
A thrust plate 5 having a spiral shallow groove 4 formed therein is arranged at the lower end of the rotary shaft 1 to form a dynamic pressure thrust bearing. This thrust plate 5 is arranged on the fixed plate 6,
The fixed plate 6 is fixed to the lower surface of the housing 7 that fixes the sleeve 2.

A flange portion 8 fixed to the rotary shaft 1
A rotary polygon mirror 9 is fixed to the upper surface of the above, and a rotor 11 to which a driving magnet 10 is fixed is fixed to the lower surface of the flange portion 8. Further, a stator coil 13 is arranged on the upper surface of the flange portion 12 of the housing 7, and a drive motor is configured between the stator coil 13 and the drive magnet 10.

Further, the housing 7 is fixed to the optical box 15 by screws 14, and an image forming lens group 17 for forming an image of the light beam deflected by the rotary polygon mirror 9 on the photosensitive drum 16 is arranged in the optical box 15. Has been done.

[0006]

However, in the above-mentioned conventional example, since the screw 14 is used to fix the housing 7 to the optical box 15, the housing 7 becomes large in size, the number of parts increases, and the cost rises. .. Further, when the accuracy of the lower surface of the flange portion 12 of the housing 7 and the mounting surface of the optical box 15 is not good, the perpendicularity between the inner diameter portion of the sleeve 2 and the flange portion 12 is poor, and the accuracy of the deflection scanning device is low. It will get worse. Further, when the rotary shaft 1 rotates at a high speed, heat is generated in the hydrodynamic bearing, and the heat is released into the optical box 15 and the performance of the rotary device or the performance of the deflection scanning device, for example, the rotation accuracy of the rotary device. And the optical accuracy of the deflection scanning device is adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a deflection scanning device having a small and highly accurate hydrodynamic bearing built-in without increasing the temperature in the hydrodynamic bearing. It is in.

[0008]

In order to achieve the above object, a deflection scanning device incorporating a hydrodynamic bearing according to the present invention has a deflector for deflecting a light beam from a light source supported by the hydrodynamic bearing. A deflection scanning device having a housing for accommodating the deflector, the deflection motor for rotating and scanning a light beam by a drive motor, and the means for condensing the light beam on the object to be scanned, comprising: The fixing member is fixed to the container by an elastic member, and the heat radiating member is provided on the fixing member.

[0009]

In the deflection scanning device having the dynamic pressure fluid bearing having the above-mentioned structure, since the fixing member of the dynamic pressure fluid bearing is fixed to the accommodating container by using the elastic member, the outer diameter of the fixing member becomes small and the whole structure becomes small. Processing accuracy is improved. Further, since the heat radiating member is attached to the fixing member, the heat of the hydrodynamic bearing is transmitted through the fixing member and radiated from the heat radiating member to the air.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a sectional view of the first embodiment, FIG.
3 is a partially enlarged sectional view of the rotary polygonal mirror 33. A rotary polygon mirror 33 is fixed to the upper surface of a flange 32 attached to the rotary shaft 31, and a drive magnet 34 and an FG magnet 35 that form a drive motor are mounted to the lower surface of the flange 32. The fixed rotor 36 is fixed. In addition, the drive magnet 34
A stator coil 37 that also constitutes a drive motor and a printed circuit board 38 on which an FG pattern is printed are arranged at positions facing the and FG magnets 35, and the stator coil 37 is fixed so as to be on the printed circuit board 38. ing. Further, in order to effectively act the magnetic field of the driving magnet 34 on the stator coil 37, an iron plate-shaped yoke 39 is fixed on the printed circuit board 38, and these stator coil 37, printed circuit board 38, and yoke 39 are connected to the motor substrate 40. Is composed of. The Hall element (not shown) and the drive circuit and control circuit formed on the printed circuit board 38 control the energization of the stator coil 37 and the rotation of the drive motor.

On the other hand, the rotary shaft 31 is rotatably fitted to a sleeve 41 which is a fixed member, and a herringbone-shaped shallow groove 42 for generating a dynamic pressure is formed at two locations on the outer peripheral surface of the rotary shaft 31. Is installed to form a dynamic pressure radial bearing. In addition, at a position facing the lower surface of the rotary shaft 31, the
As shown in FIG. 5, a thrust plate 44 having a spiral shallow groove 43 for generating a dynamic pressure is arranged together with a fixed plate 45 to form a dynamic pressure thrust bearing. The fixed plate 45 is fixed to the lower surface of the sleeve 41, and a hole 46 and a groove 47 are formed in the thrust plate 44 above the fixed plate 45 to circulate a lubricating fluid in the dynamic pressure thrust bearing. A spiral shallow groove 48 for circulating the lubricating fluid in the direction of the herringbone-shaped shallow groove 42 is engraved on the outer peripheral surface of the rotating shaft 31 near the opening of the sleeve 41. Sleeve 4 between the bone-shaped shallow grooves 42
On one side, an annular recess 49 for ensuring the stability of the lubricating fluid and at least one small diameter hole 50 are provided.

Further, in this embodiment, a flange portion 51 and an annular groove 52 are provided on the outer peripheral surface of the sleeve 41, the motor board 40 is fixed to the upper surface of the flange portion 51 by adhesion or screws, and the lower surface of the flange portion 51 is It serves as a mounting reference surface of the optical box 53 and is joined to the inner surface of the optical box 53. An annular elastic member 54 is fitted into the annular groove 52, and the elastic member 54 elastically contacts the outer side of the optical box 53 to fix the sleeve 41 and the optical box 53. Further, a radiating fin 55 is attached to the lower end of the sleeve 41 to radiate the heat of the sleeve 41 heated by the fluid into the air. Image forming lens groups 56a and 56b are arranged in the optical box 53 so that the laser beam L emitted from a light source (not shown) and deflected by the rotary polygon mirror 33 is formed on the photosensitive drum 57. ..

With this structure, the lower surface of the flange portion 51 of the sleeve 41 serves as the mounting surface of the optical box 53.
The diameter of the fixing member can be reduced, and the separate sleeve and housing as in the conventional example can be integrated. Further, since the heat radiation fins 55 are attached to the sleeve 41, the heat generated in the hydrodynamic bearing is transferred to the optical box 5.
3 can be radiated to the outside, and the temperature rise inside the optical box 53 can be prevented. Therefore, the temperature rise of the hydrodynamic bearing is eliminated, and the rotation accuracy is kept good.

Further, when the sleeve 41 is machined, the inner peripheral surface thereof, the joint surface with the fixing plate 45 and the lower surface of the flange portion 51 can be machined simultaneously, so that the machining accuracy is improved and the cost is reduced. Furthermore, if the radiation fins 55 are attached after fixing the rotating device to the optical box 53, the whole assembly becomes easy.

FIG. 3 is a sectional view of the second embodiment, in which an annular elastic member 58 is connected to a heat radiation fin 59, and the elastic member 58 is fitted in the annular groove 52, so that the sleeve is formed. 41 and the optical box 53 are fixed.

In this way, the elastic member 58 and the radiation fin 5 are
By connecting 9 together, a heat radiation effect similar to that of the first embodiment can be obtained, and the number of parts can be reduced to facilitate the assembly and the cost can be reduced.

FIG. 4 is a cross-sectional view of the third embodiment. Here, the heat dissipation fin 60 has a hole at the center for external fitting to the sleeve 41, and has an annular projection 60a on the outer circumference. It is insert-molded in the recess outside. The elastic member 54 attached to the sleeve 41 contacts the heat radiation fin 60. In this way, by integrating the radiation fin 60 and the optical box 61, the first
Also, it has the same heat radiation effect as in the second embodiment, the number of parts is reduced, the assembly is facilitated, and the cost is reduced.

[0018]

As described above, in the deflection scanning device incorporating the hydrodynamic bearing according to the present invention, since the elastic member is used when fixing the fixing member to the container, the fixing member can be made compact. Therefore, it is possible to improve the processing accuracy of the mounting surface of the housing of the fixing member. Further, since the heat radiating member is attached to the fixing member to radiate the heat generated in the hydrodynamic bearing to the outside, the heat has no adverse effect.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a partially enlarged sectional view.

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a sectional view of a third embodiment.

FIG. 5 is a sectional view of a conventional example.

[Explanation of symbols]

 31 rotating shaft 34 driving magnet 40 motor substrate 41 sleeve 51 flange portion 52 annular groove 53, 61 optical box 54, 58 elastic member 55, 59, 60 radiating fin

Claims (4)

[Claims] 1. A deflector for deflecting a light beam from a light source is rotated by a drive motor supported by a hydrodynamic bearing to deflect and scan the light beam, and the deflector, the drive motor and the light beam are collected on an object to be scanned. In a deflection scanning device having a container for accommodating a means for illuminating, a fixing member of the hydrodynamic bearing is fixed to the container by an elastic member, and a heat radiating member is provided on the fixing member. Deflection scanning device with a built-in pressure fluid bearing. 2. A deflection scanning device having a hydrodynamic bearing according to claim 1, wherein the heat radiating member is provided outside the container. 3. A deflection scanning apparatus having a hydrodynamic bearing according to claim 1, wherein the heat radiation member is integrally formed with the elastic member. 4. A deflection scanning device having a hydrodynamic bearing according to claim 1, wherein the heat radiation member is insert-molded in the container.