JPH0868958A - Rotary polygon mirror type light deflector - Google Patents

Abstract

PURPOSE: To prevent oil mist leaked from a gap between the upper surface of a polygon mirror and a labyrinth plate from being splashed by providing at least either the polygon mirror or the labyrinth plate with a groove group. CONSTITUTION: A stator is constituted of a frame 5, a rotational supporting part 12 and a coil 13 wound round a core 13 successively provided on the frame 5. The polygon mirror 1 is successively provided with a magnet 9 surrounding annularly the outside circumferential surface of the core 13 and a yoke 8 with a screw 15 through a hub 7 so as to constitute a rotor of upper and lower ball-bearings 10a and 10b supported by the supporting part 12. Besides, the labyrinth plate 2 is fixed to the supporting part 12. Then, when the rotor is rotated, air in the fine gap C flows toward the supporting part 12 by the groove group regulated in a specified direction of a film 3 cocentrically stuck to the upper surface of the mirror 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon mirror driving device constituting a rotary polygon mirror type optical deflector.
More specifically, the present invention relates to a polygon mirror driving device having a configuration that enables stable and smooth rotation of the polygon mirror and that is useful for preventing contamination of the polygon mirror due to scattering of lubricating oil.

[0002]

2. Description of the Related Art Polygon mirrors are used for a long period of time.
The surface of the drive device is contaminated by lubricating oil scattered from a ball bearing or the like of the drive device, and defects such as impossibility of incidence and reflection of a laser beam on a mirror surface at an accurate position are likely to occur. Therefore, the lubricating oil does not wrap around to the mirror surface, and moreover,
The device is designed to be small and flat.

For example, Japanese Patent Publication No. 3-716 shown in FIG.
In the device disclosed in Japanese Patent Publication No. 90, in order to prevent oil mist from the ball bearing 22 fixing the vertical shaft 21 interposed in the upper case 20 from scattering on the reflecting surface of the polygon mirror 23, the polygon mirror 23 is prevented. While fixing the corrugated plate 24 having a zigzag-shaped protrusion on the upper surface of the inside of the upper case 20, another corrugated plate 25 having a zigzag-shaped recess is inserted into the protrusion of the corrugated plate. And a small gap between the upper and lower corrugated plates, and a spencer 26 is provided on the outer circumference of the vertical shaft between the ball bearing 22 and the upper surface of the polygon mirror near the vertical shaft. A labyrinth is formed by providing an annular protrusion 27 on the upper case.

In this system, although a complicated labyrinth is constituted by the corrugated plates 24, 25, the spencer 26, the annular projection 27, etc., a means for exerting a force for controlling the flow of air forcibly scattering the lubricating oil is used. Therefore, a part of the oil mist scattered from the inside of the bearing may reach the reflecting surface of the mirror through this maze, which may reduce the reflectance of the mirror. Moreover, since it takes time to process a corrugated plate having a complicated shape and it is complicated to assemble a large number of parts, the deflector itself becomes expensive, and the productivity is extremely low and it is difficult to use.

[0005]

In view of the above situation, the present invention provides means for exerting a force for forcibly controlling the flow of air that scatters lubricating oil in at least one of the polygon mirror and the labyrinth plate. Therefore, the oil mist that leaks from the gap between the upper surface of the polygon mirror and the labyrinth plate is prevented from scattering.

[0006]

In view of the above problems, a rotary polygon mirror type optical deflector of the present invention has a ball bearing inserted in a fixed shaft, a hub rotatably supported by the ball bearing, and A rotary polygon mirror type optical deflector comprising a polygon mirror fixed to a hub and rotating integrally, wherein a part of the end face of the polygon mirror is provided on one end side of the fixed shaft with a minute gap from the end face of the polygon mirror. The labyrinth plate is fixed so as to cover, and a spiral groove group for controlling the air flow in the inner circumferential direction is formed on at least one of the end face of the polygon mirror and the labyrinth plate facing each other. The attached film is attached.

In view of the above-mentioned problems, the rotary polygon mirror type optical deflector of the present invention has a spiral groove group which is formed by inclining toward the rear side in the rotational direction from the outer circumference to the inner circumference. The gist is that the angle is less than 90 ° with respect to the tangent line on the outer circumference.

[0008]

[Function] Since at least one of the polygon mirror and the labyrinth plate is provided with a means for exerting a force for forcibly controlling the flow of the air that scatters the lubricating oil, from the gap between the upper surface of the polygon mirror and the labyrinth plate. The scattering of leaking oil mist is prevented. Therefore, the polygon mirror can be stably used even in long-term use.

[0009]

1 is a sectional view of an embodiment of a fixed axis type optical deflector according to the present invention. Descriptions that overlap with FIG. 5 are omitted. In the figure, 1 is a polygon mirror having a mirror 1a on its outer peripheral portion, 2 is a labyrinth plate, 3 is a film, 5 is a frame, 7 is a hub, 8 is a yoke made of a magnetic material, 9 is a magnet, 10a and 10b are balls. The bearing 11 is a spring that applies a predetermined preload to the ball bearing. Then, a minute gap C is formed between a part of the upper end surface of the mirror 1 and the labyrinth plate 2 covering it. It is desirable that the minute gap C is about 0.02 mm to 0.5 mm.

The above-mentioned fixed axis type optical deflector comprises a frame 5, a rotation support portion 12 erected on the frame 5, and a frame 5.
A stator is composed of a coil 14 wound around a core 13 that is continuously provided on the core 13. A magnet 9 and a yoke 8 that annularly surround the outer peripheral surface of the core are connected to the polygon mirror 1 by a screw 15 via a hub 7. These are rotatably supported by the upper and lower ball bearings 10a and 10b fitted to the rotation supporting portion to form a rotor.

The labyrinth plate 2 is fixedly mounted on the rotation support portion 12. As a result, when the rotor rotates, the lower surface of the labyrinth plate 2 and the upper surface of the polygon mirror 1 move relative to each other due to rotation. As a result, the air in the minute gap C causes a turbulent air flow if the upper surface of the polygon mirror or the lower surface of the labyrinth plate has slight irregularities. When the unevenness is defined in a specific direction, the turbulent flow becomes a constant flow.

In FIG. 1, the film 3 attached to the upper surface of the polygon mirror is a thin plastic or stainless steel plate having a thickness of about 0.05 mm to 0.2 mm formed into an annular shape by punching, and at the same time the outer peripheral surface is formed. A plurality of grooves 4 are punched from the inside toward the inside. Then, the processed film 3 is attached on a concentric circle on the inner peripheral surface of the polygon mirror. By rotating the film 3, the flow of air is controlled in the inner circumferential direction.

In the figure, the film 3 is attached to the upper surface of the polygon mirror, but it may be attached to the labyrinth plate 2 side. It may also be attached to both upper surfaces.

FIG. 2 is a view showing the shape of a plurality of grooves punched in a film. In the drawing, the groove 4 has an angle of less than 90 ° with respect to a tangent line which constitutes the outer peripheral surface of the film.
Moreover, it is formed in a quadrilateral shape in the direction opposite to the center line and in a shape penetrating from the outer peripheral surface toward the inner peripheral surface. The direction of penetration from the outer peripheral surface toward the inner surface is opposite to the rotation direction. Therefore, the plurality of grooves form a spiral groove group for controlling the air flow in the inner circumferential direction.

When an electric current is applied to the coil 14 constituting the stator fixed to the frame 5, the magnet 9 is magnetically actuated and the hub 7 integrally connected to the magnet 9 is rotated via a ball bearing. . Since the polygon mirror 1 is fixed to the hub 7 by screws 15 in the vicinity of the inner peripheral edge portion thereof, the polygon mirror 1 rotates as the hub 7 rotates, and at the same time the film 3 also rotates.

A plurality of grooves are formed in the film as described above, and each groove has an angle of less than 90 ° with respect to the tangent line forming the outer peripheral surface of the film and is directed in the direction opposite to the rotation direction. Since it is configured, the relative movement of the mirror and the labyrinth plate 2 causes an air flow in the inner circumferential direction as shown in FIG. This flow acts as a force to move the air in the minute gap C in the axial center direction, and therefore acts to control the scattering of the oil mist. In addition, since the processed film 3 is attached on the concentric circle on the inner peripheral surface of the polygon mirror, the polygon mirror rotates stably and smoothly.

FIG. 4 is another embodiment of the groove processed on the film. The plurality of grooves 16 are formed in a sword tip shape from the outer peripheral direction of the film toward the inner peripheral direction of the film.

[0018]

As described above, according to the present invention, a relative speed difference is generated between the polygon mirror and the labyrinth plate, and the air flow is controlled in the inner circumferential direction on the surfaces where they face each other with a minute gap. By providing the groove group in order to prevent the oil mist generated inside the bearing leaking from the labyrinth plate side toward the reflecting surface of the mirror, it can be almost completely blocked.

The labyrinth plate has a simple shape, and since the grooved thin plate can be easily manufactured by press working, it is not only economically efficient, but as a result, a large amount of optical deflectors can be supplied at low cost. it can.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a fixed axis type optical deflector according to the present invention.

FIG. 2 is a diagram showing shapes of a plurality of grooves punched in a film according to the present invention.

FIG. 3 is a diagram showing an air flow generated by a plurality of grooves punched in the film according to the present invention.

FIG. 4 is another example of the groove processed on the film according to the present invention.

FIG. 5 is a sectional view of an example of a conventional fixed axis type optical deflector.

[Explanation of symbols]

 1 polygon mirror 2 labyrinth plate 3 film 4 groove 7 hub 10a, 10b ball bearing 14 groove

Claims (2)

[Claims] 1. A rotary polygon mirror type optical system comprising a ball bearing inserted into a fixed shaft, a hub rotatably supported by the ball bearing, and a polygon mirror fixed to the hub and rotating integrally. In the deflector, a labyrinth plate is fixed to one end side of the fixed shaft so as to cover a part of the end face of the polygon mirror with a minute gap from the end face of the polygon mirror. A rotary polygon mirror-type optical deflector characterized in that a film having a spiral groove group for controlling an air flow in an inner circumferential direction is adhered to at least one of the end face and the labyrinth plate. vessel. 2. The spiral groove group is formed so as to be inclined from the outer circumference toward the inner circumference by a predetermined angle rearward in the rotational direction, and the predetermined angle is less than 90 ° with respect to a tangent line on the outer circumference. The rotary polygon mirror type optical deflector according to claim 1.