JPH1164773A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner capable of preventing dust from being accumulated near a scanning lens. SOLUTION: This optical scanner possesses a rotary polygon mirror 3 receiving light from a light source and reflecting it while performing scanning, the scanning lens 5 forming the scanning light from the mirror 3 into an image on a surface to be scanned, and an optical box 1 housing them. The scanner is provided with a guide plate 10 separately from the lens 5 on the side of the lens 5 opposite to the mirror 3, and an air current sent from the mirror 3 is made to extend nearly all over the exposed periphery of the lens 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device provided in an image forming apparatus, and more particularly, to prevention of contamination in an optical box used in an optical device.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional example of an optical scanning device used for a laser printer or the like. In the figure, 1 is an optical box, 2 is a light source having a laser diode or the like and emitting laser light, 3 is a rotating polygon mirror (polygon mirror) for scanning the laser light in the main scanning direction, 4 is a first cylinder lens, 5
Is a scanning lens composed of an fθ lens, and 6 is a second cylinder lens.

[0003] Of these, the first cylinder lens 4, the scanning lens 5, and the second cylinder lens 6 constitute an imaging lens system, and form an image of a laser beam on a photosensitive drum (not shown). Reference numeral 7 denotes a dust-proof glass disposed at a laser emission port opened on the front end surface of the optical box. The upper part of the optical box 1 is closed with a lid 1a.

[0004]

In the above configuration,
When dust adheres to the optical element on the optical path of the laser light, the image is disturbed or stained. In particular, since the scanning lens 5 has a large area, there is a high possibility that dirt adheres. Therefore, the optical box 1 is formed to be in a sealed state.

However, even when the optical box is formed in a sealed state, dust enters the optical box through a small gap and eventually adheres to the scanning lens 5 and the reflection surface of the mirror. Also, if the rotating polygon mirror itself deteriorates or the laser light source reaches the end of its life,
The replacement is required, and the optical box is opened. At that time, dust enters and adheres, deteriorating the image.

FIG. 7 is a view showing a state of airflow in the optical box 1. Since the rotating polygon mirror 3 is rotating, its reflecting surface becomes a wing and causes airflow in the surrounding air. This airflow flows in the direction of the arrow in the figure and reaches the scanning lens 5. Then, the scanning lens 5 hits the rotating polygon mirror 3 side, and if there is a gap above and below the rotating polygon mirror, if there is a gap only above, as shown in FIG. However, a negative pressure is generated at the lower end 5a on the opposite side of the scanning lens 5,
Dust accumulates. Since the scanning lens 5 usually has many plastic lenses, it adsorbs dust and promotes dirt.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide an optical scanning device capable of preventing dust from collecting near a scanning lens.

[0008]

In order to achieve the above object, the present invention provides a rotating polygon mirror which receives light from a light source and reflects it while scanning, and receives light scanned by the rotating polygon mirror. In an optical scanning device having a scanning lens that forms an image on a scanning surface and an optical box that houses the scanning lens, a guide plate is provided on a side of the scanning lens opposite to the rotating polygon mirror and is separated from the scanning lens. The air current sent from the scanning lens spreads over almost the entire exposed periphery of the scanning lens.

The guide plate may be formed integrally with the optical box, the scanning lens may have a shape that is long in the horizontal direction, and a gap between the optical box may be provided above and below. Plates may be provided on both upper and lower sides of the scanning lens.

[0010]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of the first embodiment of the present invention. FIG. 2 is a partially broken perspective view showing the main part. In this embodiment, a guide plate 10 is provided on a side of the scanning lens 5 opposite to the rotary polygon mirror 3. Guide plate 1
Numeral 0 is formed integrally with the lid 1a of the optical box 1 and extends from top to bottom. The scanning lens 5 is long in the scanning direction (the direction perpendicular to the drawing) as described in the conventional example, but the guide plate 10 is also almost the same length as the scanning lens 5.

With such a configuration, the rotary polygon mirror 3
In this embodiment, the airflow generated in the above-described embodiment strikes the surface of the scanning lens 5 on the rotating polygon mirror 3 side, and there is no gap below the scanning lens 5. In this embodiment, the airflow flows upward along this surface, and the gap above the scanning lens 5 Go through the other side. The airflow that flowed to the other side
It hits the guide plate 10, moves downward along the guide plate 10, reaches the lower end 5 a of the surface of the scanning lens 5 opposite to the rotary polygon mirror 3, hits the bottom surface 1 b of the optical box 1, and changes its direction in the horizontal direction. Accordingly, the airflow blows also to the lower end 5a of the scanning lens 5 where dust is liable to accumulate due to a negative pressure in the past, so that accumulation of dust can be prevented.

FIG. 3 is a diagram showing a second embodiment of the present invention. In this embodiment, the scanning lens 5 has only
And there are gaps S1 and S2 above and below. In such a case, the guide plate 10 may be provided on the upper side as shown in FIG. 1, or the guide plate 11 may be provided on the lower side of the optical box 1.
The air current generated by the rotating polygon mirror 3 hits the surface of the scanning lens 5 and is divided into upper and lower portions, and passes through both the gaps S1 and S2. The airflow that passed through the upper gap S1 goes straight as it is,
The airflow that has passed through the gap S2 below the scanning lens 5 collides with the guide plate 11, changes its direction upward, and merges with the airflow that has passed through the upper gap S1. Therefore, negative pressure cannot be applied to the lower end 5a of the scanning lens 5 on the side opposite to the rotary polygon mirror, and it is possible to prevent dust from accumulating there.

In this case, only one support 8 is provided at the center of the scanning lens 5. However, since there is only a gap under the scanning lens 5, various support methods such as two at the left and right may be used. is there.

FIG. 4 is a diagram showing a third embodiment of the present invention. In this embodiment, the scanning lens is composed of two lenses 51 and 52. The two lenses 51 and 52 are both supported by the column 8 and the like shown in FIG. A guide plate 10 is provided between the two lenses from above and a guide plate 11 is provided from below. Further, on the opposite side of the second scanning lens 52 from the rotary polygon mirror 3, there is a guide plate 12 from below.

The wind from the rotary polygon mirror 3 strikes the surface of the first scanning lens 51 and separates up and down, flows through upper and lower gaps, hits the upper guide plate 10 and the lower guide plate 11, and merges at the center. Then, the second scanning lens 52 hits the surface on the rotating polygon mirror side. Further, the airflow that separates up and down and that flows downwards hits the lower guide plate 12 and rises, merges with the airflow that flows upwards, and flows to the right in the figure.

Since the above airflow flows, dust does not accumulate in the vicinity of the scanning lenses 51 and 52, so that the scanning lenses can be prevented from being stained. Further, in this embodiment, the case where the number of the scanning lenses is two is exemplified, but the case where the number of the scanning lenses is three or more can be dealt with similarly by disposing the guide plate.

FIG. 5 is a comparative example. Here, as in FIG. 4, two scanning lenses 51 and 52 are used, and only the upper guide plate 10 is provided between them. With such a configuration, a negative pressure is generated in the vicinity of the upper portion 52a of the second scanning lens 52 on the side of the rotating polygon mirror, and a vortex is formed, and there is a possibility that dust accumulates there. Therefore, in such a case, it is desirable to attach the guide plate from above and below.

[0018]

According to the present invention as described above,
Light having a rotating polygonal mirror that receives light from a light source and reflects while scanning, a scanning lens that forms an image of light scanned by the rotating polygonal mirror on a surface to be scanned, and an optical box that accommodates them. In the scanning device, a guide plate is provided on the opposite side of the scanning lens from the rotating polygon mirror so as to be separated from the scanning lens, and the wind sent from the rotating polygon mirror is distributed over the entire periphery of the scanning lens. The accumulation of dirty dust can be prevented.

If the guide plate is formed integrally with the optical box, the guide plate can be easily manufactured, and the assembly of the optical box does not become complicated.

If the scanning lens has a shape that is long in the horizontal direction, has a gap with the optical box at the top and bottom, and the guide plates are provided at both the upper and lower sides of the scanning lens, the plurality of scanning lenses can be provided. In this case, it is possible to reliably prevent dust from adhering.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a cutaway perspective view showing a main part of the embodiment of FIG. 1;

FIG. 3 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a comparative example with the present invention.

6A and 6B are diagrams showing a configuration of a conventional optical scanning device, in which FIG. 6A is a cross-sectional view taken along line AA in FIG. 6B, and FIG. 6B is a cross-sectional view taken along line BB in FIG.

FIG. 7 is a diagram illustrating the flow of airflow in a conventional optical scanning device.

[Explanation of symbols]

 Reference Signs List 1 optical box 2 light source 3 rotating polygon mirror 5, 51, 52 scanning lens 10, 11, 12 guide plate

Claims (3)

[Claims] 1. A rotating polygonal mirror that receives light from a light source and reflects while scanning, a scanning lens that forms an image of light scanned by the rotating polygonal mirror on a surface to be scanned, and an optical lens that accommodates these. In the optical scanning device having a box, a guide plate is provided on the opposite side of the scanning lens from the rotating polygon mirror and is spaced apart from the scanning lens, and the airflow sent from the rotating polygon mirror almost entirely surrounds the exposed periphery of the scanning lens. An optical scanning device characterized in that the optical scanning device is distributed over a wide area. 2. The optical scanning device according to claim 1, wherein the guide plate is formed integrally with the optical box. 3. The scanning lens has a shape that is long in the horizontal direction, has a gap between an optical box above and below, and the guide plates are provided on both upper and lower sides of the scanning lens. The optical scanning device according to claim 1.