JPS5824167A - Optical scanning and exposing device - Google Patents

Abstract

PURPOSE:To eliminate uneven illumination, by providing plural slit plates for forming an exposing slit opening, between a projection lens and a photosensitive body, and forming the opening ends of the slit plates of one side in a nonlinear shape by placing the optical axis between them. CONSTITUTION:A light quantity control member 13 is provided with a pair of slit plates 30, 31 for forming an exposing slit opening, and these pair of slit plates 30, 31 move in the direction as indicated with an arrow, synchronizing with movement of a projection image. Also, end parts 30a, 31a of the slit plates 30, 31 have a nonlinear shape in the slit lengthwise direction in order to make an illumination distribution uniform in the slit lengthwise direction in an exposure area on a photosensitive drum 1. Also, when the slit plates 30, 31 are placed at a position for controlling a luminous flux of a main light beam 42, their turning is controlled so that the slit opening 52 falls at almost right angles with the main light beam 42. In this way, the illumination distribution on the photosensitive body becomes uniform, and uneven intensity of illumination can be eliminated.

Description

[Detailed description of the invention] The present invention relates to an optical scanning exposure apparatus.

Conventionally, in electrophotographic copying machines, there have been two methods: the nNjt method, in which the image of an original is projected onto a photoreceptor; the stationary full exposure method, in which both the original and the photoreceptor are kept stationary and exposed using a fixed optical system; Jlli.

There are scanning exposure (slit exposure) methods in which either the photoreceptor or the optical system is moved to expose the image, and the latter can be broadly divided into optical scanning exposure methods in which the document is held still and optical systems such as lenses are moved. and an original scanning exposure method in which the optical system is fixed and the original and the photoreceptor are moved.

The present invention is applied to the above-mentioned optical scanning exposure type copying machine.

In the case of an optical scanning fog light type copying machine, it is not possible to obtain a uniform illuminance distribution in the exposure area on the photoreceptor due to the effects caused by the moving position of the optical system and the characteristics of the lens itself.

Figure 1 shows the relationship between the exposure slit 8 and the irradiation light flux when a moving lens optical system is used.

B and C show images of the leading edge, center, and trailing edge of the manuscript. lx, is, Im are the moving positions of the image areas A, B, and C on the photosensitive drum E, and are the positions where the image areas A, B, and C are projected onto the photosensitive drum E through the exposure slit S. , and forms an electrostatic latent image on the photosensitive drum E corresponding to the original image. In this way, the photosensitive drum E is rotated by a certain angle from the start to the end of scanning, and the light image of each part on the original document is incident on a different area on the photosensitive drum AB. As a result, uneven illuminance occurs in the exposed area on the photosensitive drum. Not only the displacement of the scanning position of the optical system, but also the influence of the C084 power law of the lens further causes uneven illuminance on the photosensitive drum.

Conventionally, to correct such uneven illuminance, an optical filter is used or the entire slit is rotated as a unit while moving the exposure slit, but the disadvantage of the former method is that there is a large loss of light intensity. Unfortunately, the latter method results in a more complicated structure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical scanning exposure apparatus that eliminates the above-mentioned drawbacks and corrects illuminance unevenness throughout the Iw source region on a photoreceptor.

The present invention provides an optical scanning exposure apparatus in which several slit plates forming exposure slit openings are provided between a projection lens and a photoreceptor, and the opening end of at least one of the slit plates is set between the optical axis. It is characterized by having a linear shape, moving a plurality of slit plates in accordance with the movement of the projection effect, and changing the relative positions of the plurality of slit plates in accordance with the scanning position of the moving optical system. .

The present invention will be observed below with reference to a concrete example shown in the drawings. Figure 2 shows a copying machine that performs exposure using an optical scanning method. 1 is a photosensitive drum rotating in the direction of the arrow at a circumferential speed v; 2
e1 original microfilm, 3Fi microfilm lamp for illuminating people, 4 is a condensing lens, 5 is a projection lens, 6 is an integrated right-angled mirror consisting of reflective stitches 7.8 orthogonal to each other, 13 is a projection lens 5 This is a light amount regulating member disposed between the photosensitive drum 1 and the photosensitive drum 1.

The photosensitive drum 1 is composed of a three-layer photosensitive member in which a conductive layer, a photoconductive layer, and a transparent insulating layer are stacked in this order, and has an insulating layer on the surface.

This photosensitive drum is uniformly charged with a primary Teiden charger 15, and then an AC or DC static eliminator 1 with a polarity opposite to that of the negative charger 15 is charged.
6, the primary charge is removed while projecting image light on the microfilm, and then uniform exposure is performed using a lamp 17, thereby forming an electrostatic latent image in accordance with the projected image pattern.

The electrostatic latent image on the photosensitive drum 1 is developed by the developing device 918 and then transferred to the transfer paper 20 by the transfer device 19.

Here, when the microfilm 2 is projected (with the right-angle mirror unit 6 at the position indicated by the solid line), the image is enlarged and projected onto the opening of the static eliminator 16 through the image aFi optical path 25, and the right-angle mirror unit 6 is positioned at a point Mm in the direction of the arrow. The static eliminator 16 passes through the image bFi light path 26 of the microfilm 2 while moving to
The image will be enlarged and projected onto the aperture.

In this case, the moving speed of the right-angled Milani body 6 is matched with the exposure speed,
The projection gIh will be synchronized with the photosensitive drum. From the above explanation, the circumferential speed of the photosensitive drum 1 and the moving speed of the right-angle mirror unit 6 are constant regardless of the projection magnification of the lens 5, and the speed of the right-angle mirror unit 6 is constant regardless of the projection magnification of the lens 5. It will be a F season where you can do it as you like.

FIG. 3 shows the structure of the light amount regulating member F1, which has a pair of slit plates 3o and 51 forming a slit opening for the exposure light amount regulating member 16#i, and this pair of slit plates 50-
31 is arranged in synchronization with the movement of the projected image, and the first
It moves integrally with the slit plate 3o in the direction of the arrow, rotates about the fulcrum 32, and moves in and out of the opening of the first slit plate 3o. When the second slit plate 31 rotates around the fulcrum 32, the opening end 30m of the first slit plate 5o
The distance between the tips 31m of the second slit plates 31 changes, thereby controlling the size of the slit opening formed by the pair of slit plates 50-51. Note that each of the slit plates 30 and 31 may be divided into a plurality of parts, each of which can be adjusted individually, and the relative positions of the slit plates on both sides of the optical axis may be changed.

The ends 50a and 31a of the slit plates 30-31 have a non-linear shape in the longitudinal direction of the slit in order to make the illuminance distribution in the longitudinal direction of the slit uniform in the exposure area on the photosensitive drum 1.

A roller 134 provided on the back surface of the second slit plate 31 is a cam surface that controls the rotation of the second slit plate 31.
When moving in the direction, the second slit plate 31 moves along the cam surface 54 and rotates according to the shape of the cam surface. The cam surface 34 is arranged at a position that does not interfere with the projection optical path, and
In order to smoothly rotate the second slit plate 61, which is long in the direction perpendicular to the moving direction, the second slit plate 61 is provided at both longitudinal ends of the slit plate 61, respectively.

The moving speed of the slit plate 50@31 is proportional to the moving speed of the projected image, that is, the moving speed of the photosensitive drum 1, and is synchronized with the movement of the right-angle mirror unit 6.

40/41/42 microfilm 2 projection head, center, rear end principal rays are shown, light amount regulating part #13o□4
．． □Oh. 1 In FIG. 3, when the slit plates 30 and 31Fi of %1 are moved, when they are at the solid line position, that is, the position where the luminous flux of the principal ray 40 should be controlled, the end 3Qa of the first slit plate and the end 31a of the second slit plate The slit aperture 50 (a plane surrounded by the edges of the image slit plate) formed by the above is approximately perpendicular to the principal ray 40, and is located at the position indicated by the dashed dotted line, that is, at the position where the luminous flux of the principal ray 41 is to be controlled. At some point, the slit opening 51 formed by the end 30m and the end [511] is at right angles to the principal ray 51, and furthermore, when it is at the broken line position, that is, the position where the luminous flux of the principal ray 42 should be controlled, the end 30a The second slit plate 6 is formed by a cam surface so that the slit opening 52 formed by the end portion 31a and the end portion 31a is approximately perpendicular to the principal ray 52.
1 rotation is controlled. The shape of the cam surface is designed so that the rotation of the second slit plate corrects the influence of the scanning position of the optical system and the characteristics of the lens, thereby making the illuminance distribution uniform in the scanning direction. The size of the slit aperture formed by the slit plates 30 and 31 changes so as to widen the luminous flux whose principal ray is inclined with respect to the photosensitive drum compared to the luminous flux near the optical axis of the projection lens. That is, the brightness of the original axis is corrected to match the brightness near the optical axis, thereby making it possible to achieve a uniform illuminance distribution in the scanning direction without losing the phosphene.

4 and 11g5 show other embodiments of the light amount control member, and 70 is a first slit plate having an open lower part 1, and a second slit plate is slidably disposed on the first slit plate 70 of 72 ore. , 73 are the shaft 74 provided on the first slint plate 7° and the second
An arm is rotatably supported by a thin strip 75 provided on the slit plate 72, 76 is a roller rotatably provided at one end of the second slit plate 72, 77 is a cam surface that engages with the rod 176, 78
is a spring that constantly presses the rod 076 against the cam surface 77.

The slit plates 7o and 72 integrally move in the direction of the arrow in synchronization with the movement of the projected image, and when the second slit plate 72 moves, the rollers 76 move along the cam surface 77, which causes the arm 73 to pivot. 74 as a center to move between the solid line position and the two-dot chain line position, and the rotation of the arm 73 causes the second slit plate 72 to slide along the first slit plate 70,
End portion 70a of first slit plate 70 and second slit plate 72
The distance between the end portions 72a changes. By making the cam 77 into an appropriate shape, the angle 0 between the optical axis of the projection lens on the photosensitive drum and the principal ray of the light beam incident on the photosensitive drum changes when the slit plates 7o and 72 move. Correspondingly, the size of the slit opening formed by the slit plates 7o and 72 can be controlled to provide a uniform illuminance distribution in the exposure area of the photoreceptor in the scanning direction.

The end portion 70a of the first slit plate 70 has a convexly curved shape, and by setting the shape of the end portion 70m to an appropriate non-linear shape, the photoreceptor is A uniform illuminance distribution can be achieved in the light range.

FIG. 6 shows still another embodiment of the light amount regulating member,
A pair of slit plates are each rotated during movement.

In FIG. 6, a pair of slits 130 and 131 forming a slit opening are arranged on a moving table (not shown) that moves in the direction of the arrow in synchronization with the projected image, and a first slit plate 130
The second slit plate 131 is rotatable about the supporting point 135, and the second slit plate 131 is rotatable about the support 162.

Roller 136-13 on the prosthetic surface of each slit plate 150, 151
3 are provided respectively, and the rollers 136-133 F
It is in constant contact with the surface of the i-cam 64. Slit plate 1
50 and 131 move integrally with the moving table in the direction of the arrow, and during movement, rollers 136 and 133 move along the cam 154,
As a result, the first and second slit plates 130@131 rotate, and the size of the slit opening changes. The first and second slit plates 130 and 151 move from the solid line position to the dashed line position via the dashed line position, and their relative positions change during movement.

In addition to the optical scanning method shown in the embodiment in which the reflecting mirror on the image field side of the lens is moved, the present invention uses a known optical scanning method in which the lens is moved or the reflecting mirror on the object side of the lens is moved. method can be applied.

Further, the present invention can be applied to the known copy sound of Aki.

As described above, according to the present invention, the illuminance distribution on the photoreceptor in the scanning direction and the direction perpendicular to the scanning direction can be made uniform without any unnecessary loss, and the mechanism for adjusting the slit opening is simple. Therefore, the structure of the device is simple and inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the exposure slit and the irradiation light flux, Fig. 2 is a general configuration diagram of a copying machine to which the present invention is applied - Fig. 3 is a configuration diagram of the light amount regulating member, and Fig. 4 is the light amount regulating member FIG. 5 is a cross-sectional view taken along line 2--v in FIG. 4, and FIG. 6 is a configuration diagram showing still another embodiment of the light amount regulating member. 1...Photosensitive drum 5.0...Projection lens 7.
8...Reflector 1! 1...Fist light amount regulation member appearance Canon Co., Ltd. 1 Tsugusuji? 2

Claims (1)

[Scope of Claims] (1) In an apparatus for projecting a stationary manuscript onto a moving optical system and exposing the projected image to a moving photoreceptor through a slit, an exposure slit is provided between the projection lens and the photoreceptor. A plurality of slit plates forming an aperture are provided, and the aperture width of the slit plate on at least one side of the optical axis is made into a non-linear shape in the longitudinal direction of the slit plate, and the positions of the plurality of slits are changed. An optical scanning exposure device characterized by: 2) The slit plate on at least one side of the plurality of slit plates with the optical axis in between rotates around the end opposite to the opening end as a fulcrum.
The optical scanning exposure apparatus described in 1. (3) Optical scanning wr according to claim 2, characterized in that the size of the slit opening is changed by rotating the slit plate by moving the netrite plate along the cam surface. Original device. (4) The opening end of the slit plate on at least one side of the plurality of slit plates should be moved toward and away from the open end of the slit plate on the other side with the shafts in between. An optical scanning exposure apparatus according to claim 1. (5) By moving the slit plate along the cam surface, the slit plate on one side is moved along the slit plate on the other side to change the size of the slit opening. An optical scanning exposure apparatus according to claim 4.