JPH06160751A - Light deflection device - Google Patents

Abstract

PURPOSE:To provide a light deflection device which improves the cooling efficiency of a housing by forcible air cooling and whose temperature-rise is reduced. CONSTITUTION:In the light deflection device 10 obtained by supporting a rotating member 13 to which a mirror 22 is fitted on a housing 11 through a bearing freely rotatably and driving and rotating the rotating member 13 by a motor M; plural fins 30 set almost in parallel with air flow for the forcible air cooling are provided on at least one part of the outside surface of the housing 11. By the fins 30, the heat radiation of the housing 11 is promoted and the cooling efficiency is improved. Besides, the temperature-rise of the device 10 is suppressed and printing quality is prevented from being deteriorated caused by thermal deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector having a low temperature rise.

[0002]

2. Description of the Related Art Conventionally, as an optical deflector, for example, FIG.
There is something like. In this conventional example, the housing 1
A sleeve 3 is rotatably fitted to a fixed shaft 2 provided upright in the center of the lower member 1A via a radial dynamic pressure fluid bearing R. The lower end surface of the sleeve 3 and the upper surface of the lower member 1A facing the lower end surface of the sleeve 3 constitute a thrust dynamic pressure fluid bearing S.

A mirror 6 and a rotor magnet member 7 constituting a drive motor M are attached to the outer peripheral surface of a sleeve 3 which is rotatably supported by the radial dynamic pressure fluid bearing R and the thrust dynamic pressure fluid bearing S. The stator coil 8 that faces the rotor magnet member 7 in the radial direction with an air gap is provided between the lower member 1A of the housing.
It is attached to the inner circumference of.

As shown in FIG. 4, the optical deflector 10 is set in an optical box 9 for use. The lower part of the set optical deflector 10 is forcibly cooled by the air flow X sent from the cooling fan F.

[0005]

The above-mentioned optical deflecting device is used in digital copying machines, laser printers, etc., but with the improvement of printing quality and the increase of copying speed, higher and higher rotation speeds are required. There is. Conventionally, the rotational speed has been used at 10,000 rpm or less, but recently, the rotational speed of 20 to 40,000 rpm has been required.

At such a high speed rotation, the heat generated by the wind loss of the mirror and the friction loss of the bearing due to the friction between the bearing surface and the air increases, and the temperature of the optical deflector rises. As a result, the optical box in which the optical deflector is set is deformed by heat, which adversely affects the accuracy of the optical system, and as a result, the printing quality deteriorates. Moreover, recently, because of cost reduction, the optical box is becoming an integrally molded product of aluminum die casting and plastic, and the influence of heat is becoming more prominent because heat dissipation due to heat conduction cannot be expected.

However, there is a limit in reducing wind loss of the mirror and friction loss of the bearing. Therefore, how to efficiently dissipate heat from the housing is a decisive factor in reducing the temperature rise of the optical deflector. Normally, the optical deflector is forced to cool the outside of the housing by a cooling fan, but with the conventional optical deflector, the surface area of the external shape of the device is small and efficient cooling is difficult, and the temperature rise becomes large. Was inevitable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical deflecting device which raises the cooling efficiency of a housing by forced air cooling and has a small temperature rise.

[0009]

According to the present invention, which achieves the above object, an optical deflector in which a rotating member having a mirror mounted thereon is rotatably supported by a housing through a bearing, and the rotating member is rotationally driven by a motor. In the apparatus, a plurality of fins substantially parallel to the forced cooling air flow are provided on at least a part of the outer surface of the housing.

[0010]

The fins, which are provided on the outer surface of the housing and are substantially parallel to the cooling airflow, promote heat dissipation from the housing. As a result, the cooling efficiency is increased, and the temperature rise is small even in the optical deflector rotating at high speed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of an embodiment of the present invention, and FIG. 2 is a bottom view thereof. First, the structure will be described. The housing 11 of the optical deflector 10 includes a lower member 11A and an upper member 11A.
Three members, B and the fixed shaft 12, form a sealed structure. The lower member 11A is made of a metal having good formability and thermal conductivity such as aluminum alloy, aluminum alloy die casting, and zinc alloy die casting, and a plurality of plate-shaped cooling fins 30 are provided on the bottom surface of the cylindrical lower member 11A. It is arranged in parallel with the forced cooling air flow X. On the other hand, the upper member 11B is the lower member 1
It is made of the same metal material or synthetic resin as 1A.

A fixed shaft 12 is erected at the center of the lower member 11A, and the bottom surface of the fixed shaft 12 and the bottom surface of the lower member 11A are on the same plane, and the fixed shaft 12 has a bearing clearance therebetween. A sleeve 13 as a rotating member is rotatably fitted. The radial bearing surface 1 is formed on the inner peripheral surface of the sleeve 13.
4 is provided and faces the radial receiving surface 15 provided on the outer peripheral surface of the fixed shaft 12. At least one of the radial bearing surface 14 and the radial receiving surface 15 (in this embodiment, the radial bearing surface 14) is provided with a herringbone-shaped groove 16 for generating a dynamic pressure to form a radial fluid bearing R. There is.

A magnet member 18 made of a permanent magnet is attached to the free end of the fixed shaft 12, while another magnet member (or a magnetic member) 20 is attached to the inner periphery of the upper end of the sleeve 13. The two magnetic members 18 and 20 face each other in a non-contact manner and attract each other to form a thrust magnetic bearing S. The magnetizing directions of the magnet members 18, 20 may be radial or axial. The sleeve 13 is made of a non-magnetic material so as not to adversely affect the magnetic circuit of the thrust magnetic bearing S. For example, a hard aluminum alloy that is light and has excellent wear resistance is optimal. The fixed shaft 12 is preferably made of non-magnetic stainless steel that is hard to rust or a hard aluminum alloy.

The magnetic attraction of the thrust magnetic bearing S supports the sleeve 13 in the axial direction. Sleeve 13
Has a small flange 21 slightly protruding on the outer peripheral surface, and the aluminum alloy mirror 2 is provided on the upper surface of the flange 21.
2 is attached. The rotor magnet 23 of the drive motor M is fitted under the outer peripheral surface of the sleeve 13. Also, the outer peripheral surface 23a of the rotor magnet 23
Are radially opposed to the inner peripheral surface 24a of the stator coil 24 arranged on the inner peripheral surface of the housing 11 via an air gap.

Reference numeral 25 is a glass window provided on the side surface of the upper member 11B of the housing so as to face the reflecting surface of the mirror 22. Next, the operation will be described. The light deflector 10 is set in the optical box as in the conventional case. The sleeve 13 of the bearing device that mounts the mirror 22 and is fitted to the fixed shaft 12 is supported by the thrust magnetic bearing S so as to float in the axial direction.
When the light deflecting device 10 is operated, the cooling fan is started to cause the airflow X to flow in parallel with the cooling fins 30. This air flow X can pass between a large number of cooling fins 30 with a small resistance, so that the flow is not obstructed and efficient cooling is performed.

When the sleeve 13 is rotated by the operation of the drive motor M, the groove 16 for generating the dynamic pressure of the radial dynamic pressure fluid bearing R is formed.
By the pumping action of, the dynamic pressure is generated in the radial bearing clearance between the radial bearing surface 14 and the radial receiving surface 15, so that the sleeve 13 is supported in the radial direction completely in a non-contact manner, and has a short rising time. High speed rotation can be reached.

At high speed rotation, the windage of the mirror 22 and heat generation due to friction between the bearing surfaces of the thrust magnetic bearing S and the radial dynamic pressure fluid bearing R and air increase, and the fixed shaft 1
2 or directly through the housing 11 to the fin 30
Transfer heat to. Since the fins 30 having a large heat radiation area are forcibly cooled by the airflow X and the heat energy of the heat generation is rapidly dissipated and removed, the temperature rise of the optical deflector 10 is effectively suppressed. It Therefore, it is possible to prevent the phenomenon that the optical box 9 in which the light deflection device 10 is set is deformed by heat and adversely affects the accuracy of the optical system, and it is possible to obtain good print quality.

Although the fins 30 are provided only on the bottom surface of the lower member 11A of the housing 11 in this embodiment,
Not limited to this, it may be provided on the upper surface of the upper member 11B,
Alternatively, it may be provided on both the bottom surface of the lower member 11A and the top surface of the upper member 11B. Further, fins may be provided auxiliary on the outer diameter surface of the housing 11, but in that case, the fins cannot be provided in parallel with the air flow X, so it is preferable to radially extend from the fixed axis.

The fins 30 may be formed separately from the housing 11 and attached to the housing 11 later, or may be integrally formed with the housing 11. Further, the housing upper member 11B that covers the light deflecting device 10 is not always necessary and may be omitted.

Further, the type of bearings provided inside the optical deflector 10, the shape of the housing 11 and the shape of the fins 30 are not limited to those in the embodiment. Further, the motor type may be an inner rotor motor, an outer rotor motor or a plane facing motor.

[0021]

As described above, according to the optical deflecting device of the present invention, since at least a part of the outer surface of the housing is provided with the plurality of fins substantially parallel to the forced cooling air flow, the cooling air is provided. Since the light deflecting device can be efficiently cooled because it does not obstruct the flow of current and has a large heat dissipation area, it is possible to prevent the accuracy deterioration of the optical system due to thermal deformation, and thus prevent the deterioration of the print quality. .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

2 is a bottom view of what is shown in FIG. 1. FIG.

FIG. 3 is a vertical sectional view of a conventional optical deflector.

FIG. 4 is an explanatory diagram of a usage mode of the optical deflecting device.

[Explanation of symbols]

 10 Optical Deflection Device 11 Housing 12 Fixed Shaft 13 Rotating Member 22 Mirror 30 Fin M Motor

Claims (1)

[Claims] 1. An optical deflector in which a rotating member having a mirror attached thereto is rotatably supported by a housing via a bearing, and the rotating member is rotationally driven by a motor, in which force is applied to at least a part of an outer surface of the housing. An optical deflecting device comprising a plurality of fins substantially parallel to a cooling air flow.