JPH08271823A - Scanning optical device - Google Patents

Abstract

PURPOSE: To prevent noise and the contamination of the deflecting and reflecting surface of a light deflector at the time of rotating a polygon mirror by covering the entire deflecting and reflecting surface with light transmissive resin. CONSTITUTION: The periphery of the deflecting and reflecting surface 4 of the polygon mirror 3 is spherically covered with the light transmissive resin 14. The mirror 3 is positioned at the center of the resin 14. The mirror 3 is fixed on a shaft 15 supported by a motor 16. By such constitution, the flow of air on the surface 4 of the light deflector becomes smooth, so that a wind whistle is prevented because the air is cut by the angle part of the surface 4, and the surface 3 of the mirror 3 is prevented from being stained by dust in the air caused by the turbulent flow of the air occurring behind the angle part of the surface 4 and from being bedewed because dew is condensed by the change of air density in the turbulent flow at the time of rotating the mirror 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device using a polygon mirror.

[0002]

2. Description of the Related Art Conventionally, a scanning optical device has been used in an image forming apparatus using an electrophotographic system.

An example of a conventional scanning optical device will be described below with reference to FIG. FIG. 7 is a schematic perspective view of a conventional scanning optical device. In FIG. 7, the light flux emitted from the light source 1 is linearly imaged by the cylindrical lens 2 as the first imaging optical system. On the other hand, in the vicinity including the image formation position, a plurality of deflective reflection surfaces 4 of the polygon mirror 3 are provided.
One of them is set to be sequentially positioned according to the rotation. The line image formed on the deflecting / reflecting surface 4 is the second line image.
The light is emitted through the fθ lens 5 as an image forming optical system to form a point image 8 on the image plane 7 on the medium 6 to be scanned, and a straight line 9 corresponding to the rotation of the polygon mirror 3 in the arrow direction. Scanned over. This scanning is called main scanning, and its direction is called main scanning direction XX. Further, scanning in the direction orthogonal to the main scanning direction XX on the image plane 7 is referred to as sub-scanning, and that direction is referred to as sub-scanning direction YY.

Next, the correction of the surface tilt of the polygon mirror 3 will be described with reference to FIG. FIG. 8 is a side view of the conventional scanning optical device in the sub-scanning direction Y-Y. In FIG. 8, when the deflecting / reflecting surface 4 causes a plane tilt in the sub-scanning direction Y-Y as indicated by a broken line 10, a point image 8 on the image plane 7 when no plane tilt occurs passes through the optical path of the broken line 11. In order not to shift to the point image 12, the deflection reflection surface 4 and the point image 8 on the image surface 7 are maintained in an optically conjugate relationship in the sub scanning direction Y-Y cross section of the fθ lens 5.

[0005]

However, in the above-mentioned conventional structure, since the polygon mirror 3 is formed in a polygonal shape, there is a problem that a wind noise is generated by cutting air at its corners during rotation. Had. Further, as shown in FIG. 9, when the polygon mirror 3 is rotating in the direction of the arrow, a turbulent flow 13 of air occurs behind the corners of the respective deflective reflection surfaces 4 during rotation, causing dust and turbulence in the air. Condensation generated due to a change in the air density in the flow 13 is struck on the surface of the polygon mirror 3 to contaminate the surface of the deflective reflection surface 4 and reduce the reflectance. Since this development remarkably appears behind the corners of each deflective reflection surface 4, the light energy reached from the light source 1 on the scanning start side on the image surface 7 of the medium 6 to be scanned decreases, and the medium 6 to be scanned 6 is reduced. It has a problem that the light energy distribution is significantly deteriorated.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a scanning optical device capable of preventing noise generated when the polygon mirror 3 is rotated and contamination of the deflection reflection surface 4. .

[0007]

To achieve this object, the scanning optical device of the present invention covers the entire deflective reflection surface of the optical deflector with a light-transmissive resin.

[0008]

With this configuration, the air flow on the surface of the deflecting reflection surface of the optical deflector becomes smooth, and the wind noise generated by cutting the air at the corners of the deflecting reflection surface during rotation and the deflection noise of each deflecting reflection surface. It is possible to prevent the dust in the air due to the turbulent flow of air generated behind the corners and the adhesion of the dew condensation caused by the change in the air density in the turbulent flow to the surface of the deflective reflection surface.

[0009]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of a main part of a scanning optical device according to a first embodiment of the present invention. In FIG. 1, 3 is a polygon mirror, and 4 is a deflecting / reflecting surface, which is covered with a light-transmitting resin 14 in a spherical shape. The polygon mirror 3 is located at the center of the light transmissive resin 14. Reference numeral 15 is a shaft supported by a motor 16, to which the polygon mirror 3 is fixed.

As described above, by covering the surface of the polygon mirror 3 with the light-transmitting resin 14 in a spherical shape, the wind noise at the corners of the polygon mirror 3 generated at the time of rotation and the turbulent flow in the air It is possible to prevent dust and dew condensation caused by a change in air density in the turbulent flow from adhering to the surface of the polygon mirror 3.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a sectional view of a main part of a scanning optical device according to the second embodiment of the present invention.
In FIG. 2, the configuration is the same as that in FIG. 1, except that the surface of the light transmitting portion of the light transmitting resin 17 that covers the periphery is formed by a part of a sphere.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a sectional view of a main part of a scanning optical device according to the third embodiment of the present invention.
In FIG. 3, the configuration is the same as that in FIG. 1, except that the surrounding light-transmissive resin 18 is formed in a disk shape.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to FIG. FIG. 4 is a sectional view of a main part of a scanning optical device according to the fourth embodiment of the present invention.
4, the configuration is the same as that of FIG. 1, except that the surrounding light-transmissive resin 19 is formed in a cylindrical shape.

(Embodiment 5) A fifth embodiment of the present invention will be described below with reference to FIGS. FIG. 5 is a sectional view of the main parts of a scanning optical device according to the fifth embodiment of the present invention. In FIG. 5, the configuration is similar to that of FIG.
The difference is that the shape 21 in the optical axis direction of the deflecting / reflecting surface 4 of the light transmissive resin 20 covering the periphery is similar to the refracting power of the cylindrical lens 2 as the first imaging optical system shown in FIG. And the first imaging optical system is removed. FIG. 6 is a side view of the scanning optical device according to the fifth embodiment of the present invention. The light flux from the light source 1 forms a line image in the vicinity of the deflection reflection surface 4 due to the curvature 22 of the surface of the light transmissive resin 20, and in the sub-scanning direction of the fθ lens 5 as the second imaging optical system, the deflection reflection surface 4 is formed. 4 and image plane 7
The above point image 8 is kept in an optically conjugate relationship.

[0015]

As described above, according to the present invention, by covering the entire deflecting reflection surface of the optical deflector with the light transmitting resin, noise such as wind noise generated when the optical deflector rotates and the deflecting reflection surface. It is possible to prevent stains generated on the top.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a scanning optical device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a scanning optical device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts of a scanning optical device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a scanning optical device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a scanning optical device according to a fifth embodiment of the present invention.

FIG. 6 is a side view of a scanning optical device according to a fifth embodiment of the present invention.

FIG. 7 is a schematic perspective view of a conventional scanning optical device.

FIG. 8 is a side view of a conventional scanning optical device in a sub scanning direction YY.

FIG. 9 is a diagram showing turbulent air flow during rotation of a polygon mirror of a conventional scanning optical device.

[Explanation of symbols]

 1 Light Source 2 Cylindrical Lens 3 Polygon Mirror 4 Deflection Reflecting Surface 5 fθ Lens 6 Scanned Medium 7 Image Surface 8 Point Image 9 Straight Line 13 Turbulent Flow 14, 17, 18, 19, 20 Light Transmitting Resin 15 Shaft 16 Motor 21 Shape 22 curvature

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Noda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Tetsuhiro Tsuru, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Hideki Yasuda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A light deflector having a deflecting / reflecting surface for reflecting and scanning light emitted from a light source onto a medium to be scanned, and a light-transmissive resin covering the entire deflecting / reflecting surface. Scanning optics. 2. A first image forming optical system for forming a linear image of a light beam emitted from a light source, and a deflection reflecting surface is provided near an image forming position of the first image forming optical system. An optical deflector, a medium to be scanned which is scanned by the light beam deflected by the light deflector, and an optical path of the light beam, which is disposed between the medium to be scanned and the optical deflector, and which is provided with the deflection reflection. A second image forming optical system for keeping the surface and the medium to be scanned in an optically conjugate relationship and for forming an image of a light beam on the medium to be scanned; and a light transmissive resin covering the entire deflecting and reflecting surface. A scanning optical device characterized in that 3. The scanning optical device according to claim 1, wherein the shape of the light transmissive resin is spherical. 4. The scanning optical device according to claim 1, wherein the light transmissive resin has a spherical shape. 5. The scanning optical device according to claim 1, wherein the light-transmissive resin has a disk shape. 6. The scanning optical device according to claim 1, wherein the light-transmissive resin has a cylindrical shape. 7. The scanning optical device according to claim 1, wherein the function of the first imaging optical system is provided in the light transmissive resin.