JPH1184792A - Image forming device - Google Patents

Abstract

(57) [Problem] To provide an image forming apparatus capable of reducing the size and having a long life of a polygon mirror. An optical scanning unit is disposed obliquely below a bottom surface of a tray, above a photosensitive drum and a fixing device, and along the bottom surface of the tray with the photosensitive drum side facing upward. Set up. Further, a polygon mirror 5b in the optical scanning unit 5 is disposed above, that is, on the photosensitive drum 9 side, and a first reflection mirror 5d and a second reflection mirror 5 are disposed.
e, image information is formed on the photosensitive drum 9 from above through the third reflection mirror 5f.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having an optical scanning unit disposed above a photosensitive drum and a fixing device.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, as shown in FIG.
09 and the fixing device 120, and there is a structure in which a face-down discharge tray 106 is provided above the optical scanning unit 105 (Japanese Patent Laid-Open No. 3-1).
05308).

The optical scanning unit 105 includes a laser module (not shown), a polygon mirror 105b, a lens group 105c, mirrors 105d and 105e, and the like. A polygon mirror 105b provided on the photosensitive drum 109 side is provided. Forward light α, which is reflected light of the fixing device 120, reaches the fixing device 120 side mirror 105d,
The return light β, which is the reflected light of 5d, reaches the upper side substantially at the center of the optical scanning unit 105, and is turned back by the mirror 105e to form image information on the photosensitive drum 109.

[0004]

However, the conventional FIG.
In the image forming apparatus as shown in (1), since the optical scanning unit 5 is disposed horizontally, a useless space γ is created between the optical scanning unit 105 and the fixing device 120, thereby realizing miniaturization. Had limitations.

In order to solve this problem, as shown in FIG. 4, the optical scanning unit 205 is arranged obliquely with the photosensitive drum 209 side upward, so that an image without wasted space γ is eliminated. There is a forming device (Japanese Unexamined Patent Publication No. 9-6
No. 8837).

However, the optical scanning unit 205 shown in FIG.
Since the polygon mirror 205b is located on the fixing device 220 side, the high heat generated in the fixing device 220 causes the polygon mirror 20
5b, and the life of the polygon mirror 205b is shortened by the influence of heat.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made to provide an image forming apparatus which can be downsized and has a long life of a polygon mirror. In an image forming apparatus in which an optical scanning unit including a module, a polygon mirror, an fθ lens, and a mirror is disposed above a photosensitive drum and a fixing unit, the optical scanning unit is inclined with the photosensitive drum side facing upward. And a polygon mirror is arranged on the photosensitive drum side, the outward light reflected by the polygon mirror reaches the fixing device side mirror, and the return light reflected by the fixing device side mirror is reflected by the photosensitive member. This is an image forming apparatus that returns to the drum side, turns back on the photosensitive drum side mirror, and forms image information on the photosensitive drum. With such a configuration, the polygon mirror can be disposed at a position farthest from the fixing device, and at the same time, no useless space in the image forming apparatus is formed.

Further, according to the present invention, the optical scanning unit is configured so that the height of the light is higher in the order of the polygon mirror installation surface, the light emitted from the laser module and the outward light, the upper surface of the polygon mirror, and the backward light. Through
It is configured to reach the end surface on the photosensitive drum side. With such a configuration, the maximum optical path length can be obtained in the optical scanning unit.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of an image forming apparatus in which a multiple transfer mechanism is stored.
Around the photosensitive drum 9 rotating clockwise in the figure, a developing unit 10, a transfer roller 19, a cleaner 11 for the photosensitive drum, and a charging unit 8 are arranged along the rotating direction. The developing device 10 is provided with a developing roller 10a,
The surface of the developing roller 10a is separated from the surface of the photosensitive drum 9 by a predetermined distance. The developing device 10 is configured to be able to appropriately supply a predetermined amount of toner from the toner container 31. The upper door 7 is disposed above the toner container 31 so as to be openable and closable about the base 7a in the direction of the arrow, and the toner container 31 is configured to be detachable. An optical scanning unit 5 that forms dots of an image on the surface of the photoconductor drum 9 is provided above the photoconductor drum 9. The multiple transfer mechanism 2 is disposed below the conveyance path 36 where the registration roller 18, the transfer roller 19, the pressure roller 24, and the like are formed. The multiple transfer mechanism 2 is integrally formed as a unit, and is detachably mounted on the apparatus main body. At the lower part 61 of the image forming apparatus 1 below the multiple transfer mechanism 2, although not shown, a recording paper container is arranged detachably from the outside, and the recording paper container is provided with a pre-transfer recording paper storage, The recording paper is transported to a transport path 35 by transport rollers (not shown), and can be transported by the transport rollers 32 and 33 to the registration rollers 18 and 30 through the passage 34. On the left side of the image forming apparatus 1, a fixing unit is formed by fixing rollers 23 and 24, and the recording paper that has passed between the photosensitive drum 9 and the transfer roller 19 is fixed by the fixing rollers 23 and 24. Passes through the passage 27 by the conveying rollers 21, 22, 25, 26,
The rollers 28 and 29 are configured to be stacked on the tray 6.

In the present invention, the optical scanning unit 5 is connected to the tray 6
, Above the photosensitive drum 9 and the fixing device 20, and obliquely along the bottom surface 40 of the tray 6 with the photosensitive drum 9 side facing upward.

Further, as shown in FIG. 2, which is a schematic sectional view of the optical scanning unit 5, the optical scanning unit 5 is a laser module 5 comprising a semiconductor laser, a collimating lens, a cylindrical lens, etc., which is included in a normal optical scanning unit.
a, a polygon mirror 5b, and an fθ lens 5c,
In the present invention, the polygon mirror 5b is disposed above, that is, on the photosensitive drum 9 side, and the photosensitive drum 9 is disposed from above through the first reflecting mirror 5d, the second reflecting mirror 5e, and the third reflecting mirror 5f. Is characterized in that the image information is formed into an image.

As a result, no unnecessary space is formed in the image forming apparatus 1, and the polygon mirror 5b is kept as far as possible from the fixing unit 20, which is the hottest in the image forming apparatus 1.

Further, in this embodiment, the polygon mirror mounting surface A, the height B of the light emitted from the laser module and the outward light α, the upper surface C of the polygon mirror 5b, and the height D of the return light β are increased in this order. As a result, the return light β passes above the polygon mirror 5b and can reach the end surface on the photosensitive drum 9 side, and an optical path length approximately twice as long as the optical scanning unit 5 is obtained. Can be.

Thus, the focal length can be designed to be long, the angle of view can be designed to be narrow, the lens configuration can be simplified, and an optical system having excellent scanning optical characteristics can be obtained. Also, by narrowing the angle of view, a polygon mirror with a large number of strokes can be used,
Since the number of rotations of the polygon mirror can be reduced, the life of the motor can be extended and the noise can be reduced.

[0015]

As described above, according to the image forming apparatus of the present invention, the optical scanning unit is arranged obliquely with the photosensitive drum side facing upward, and the polygon mirror is arranged on the photosensitive drum side. Accordingly, it is possible to reduce the size of the image forming apparatus and to provide an image forming apparatus with a long life of the polygon mirror.

Further, the optical scanning unit is configured so that the height becomes higher in the order of the polygon mirror installation surface, the outgoing light and outgoing light of the laser module, the upper surface of the polygon mirror, and the return light.
The return light passes above the polygon mirror and reaches the end surface on the photoconductor drum side, so that the maximum optical path length can be provided. Even if the optical scanning unit is miniaturized, the transfer paper is large in size. An image forming apparatus that can sufficiently cope with the above problem can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an image forming apparatus of the present invention.

FIG. 2 is a sectional view showing an optical scanning unit of the present invention.

FIG. 3 is a cross-sectional view illustrating a conventional image forming apparatus.

FIG. 4 is a cross-sectional view illustrating a conventional image forming apparatus.

[Explanation of symbols]

 1: Image forming apparatus 2: Multiple transfer mechanism 5, 105, 205: Optical scanning unit 5a: Laser module 5b, 105b, 205b: Polygon mirror 5c: fθ lens 5d: First reflection mirror 5e: Second reflection mirror 5f : Third reflective mirror 6, 106: Tray 7: Upper door 7a: Base 9, 109, 209: Photoconductor drum 10: Developing device 10a: Developing roller 11: Cleaner 18, 30: Registration roller 19: Transfer roller 20, 120, 220: fixing device 21, 22, 25, 26, 32, 33: transport roller 23, 24: fixing roller 27, 34: passage 28, 29: roller 31: toner container 35, 36: transport path 40: bottom surface 105c : Lens group 105d, 105e: mirror

Claims (2)

[Claims] 1. A laser module, a polygon mirror, fθ
In an image forming apparatus in which an optical scanning unit including a lens and a mirror is disposed above the photosensitive drum and the fixing device, the optical scanning unit is disposed obliquely with the photosensitive drum side facing upward, A polygon mirror is provided on the photosensitive drum side, and outward light, which is reflected light of the polygon mirror, reaches the fixing device side mirror, and return light, which is reflected light of the fixing device side mirror, is directed to the photosensitive drum side. An image forming apparatus, wherein the image forming apparatus is configured such that the image information is formed on the photosensitive drum by being returned by a mirror on the photosensitive drum side. 2. The optical scanning unit according to claim 1, wherein the polygon mirror mounting surface, the surface on which the laser module emits light is installed and the forward light, the polygon mirror upper surface, and the return light increase in this order. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus passes through the photoconductor and reaches an end surface on the photosensitive drum side.