JPS59201036A - Copying machine - Google Patents

Abstract

PURPOSE:To obtain a copying picture with good pictue quality by using an absorbing filter for correcting uneven illumination intensity. CONSTITUTION:A slide picture is projected to a Fresnel lens 3 through a mirror 23 and an absorbing filter 22 by using a slide projector 24. As for this projected image, an uneven illumination intensity is corrected by the absorbing filter 22, therefore, the brightness of a part of the same density of the center part of the slide and its circumferential part is the same. This projected image is slit-exposed onto a photosensitive body 10 rotating in the direction as indicated with an arrow by an exposure scanning optical system consisting of moving mirrors 5, 6, a lens 7 and fixed mirrors 8, 9. In this case, an electrostatic latent image on the photosensitive body 10 is even since the projected image is uniform. Accordingly, thereafter, this electrostatic latent image is developed by a developing device 13, a copying picture transferred and fixed to a transfer material 14 which ..is contained in a paper feed cassette 18 and fed in by a paper feed roller 17, through a transfer charger 15 and fixing rollers 19, 20 is obtained with uniform picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a projection type copying machine that copies a projected image of a slide or the like.

Conventionally, a slide is projected onto a Fresnel lens on a document table using a slide projector, and the projected image is scanned using a single light guide slit exposure using a slit exposure optical system, followed by development, transfer, and fixing. In a projection-type copying machine that obtains a copy image by performing this process, the illuminance of the projected image projected by the slide projector is uneven, making it impossible to obtain a copy image of uniform quality. This is because this is due to the aperture eclipse of the lens of the slide projector and the cos θ law.Therefore, if a slide projector uses a colorless and transparent slide to project light onto a Fresnel lens, ＼ this Fresnel The relative illuminance distribution on the document surface directly under the lens produces a phenomenon of uneven illuminance, as shown in FIG. 1, in which the center of the image is bright and it becomes darker toward the periphery. Therefore, it was inevitable that the image quality of the key-copied image would deteriorate if this illuminance unevenness was not corrected.

In view of the above points, the present invention has been made to eliminate the above drawbacks, and is designed to maintain the homogeneity of the image projected from the slide projector onto the Fresnel lens using an absorption filter that corrects uneven illuminance. , an object of the present invention is to provide a copying machine that can produce a copy image of good quality from this projected image.

FIG. 2 is a schematic diagram of a copying machine equipped with an image recording device according to the present invention. In the figure, / is the main body of the device, and there is a document placement table on the top! is provided, and a Fresnel lens 3 is further provided thereon. 22 is an absorption filter, and its light transmittance decreases toward the center as shown in Figure 3 (however, the position in the figure is the center of the absorption filter). It is provided on the lens 3.

,l! 2 is a slide projector which forms a projected image of the slide via a mirror 23 onto a Fresnel lens 3 via an absorption filter 22. Note that when the absorption filter 22 is removed and light is projected using a slide projector using a colorless transparent slide, the Fresnel lens 3
The illuminance directly below, that is, the relative illuminance above the document table is shown in Figure 1 (
However, as shown in the figure (the center of the Fresnel lens 3), it becomes higher toward the center. Therefore, when the absorption filter 22 is placed on the Fresnel lens 3 in this state, the unevenness in illuminance directly under the Fresnel lens 3 is corrected by the absorption filter 22 and removed as shown in FIG. 7, and the illuminance becomes uniform. It will be something like this.

A light source is provided at G, a movable mirror is provided at 7, a surface exposure source 72' is provided, a developing device/3, a transfer charger/3, and a cleaning device/O are provided. Also, /ri is a transfer material, /7 is a paper feed roller, 7g is a paper feed cassette, /9. ．． 20 is a fixing roller, and 2/ is a tray.

Next, the operation of the copying apparatus according to the present invention will be explained with reference to FIGS. 2 to 7. First, using the slide projector 2, an image of a slide loaded with an image is projected onto the Fresnel lens 3 via the mirror 23 and the absorption filter 22. This projected image is corrected for uneven illumination by the absorption filter 22, so if you compare the projected areas of the center and periphery of the slide, the central area will be brighter and the periphery will be brighter. It is not that the other parts are darker, but the brightness is the same. This projected image is subjected to slit exposure onto the photoreceptor 10 rotating in the direction of the arrow shown in the figure by an exposure scanning optical system consisting of a moving mirror left, a lens 7, a fixed mirror 9, and a fixed mirror 9. In this case, the charge is removed by pre-exposure by a means not shown, then sequentially charged by the primary charger//, and then charged by the secondary charger/2 simultaneously exposed to the slit as described above. The electrostatic latent image formed on the photoreceptor 10 by exposing the entire surface to light 72' has no unevenness because the above-mentioned projected image is uniform. Therefore, after this electrostatic latent image is developed by the developing device/3, it is stored in the paper feed cassette/g via the transfer charger/3, fixing rollers/9° and 20, and the paper is fed. Transferred to the transfer material /g fed by roller /7.

The image quality of the fixed and formed copy image is uniform.

In the above embodiment, the absorption filter 22 is placed on the Fresnel lens 3, but it may also be placed directly under the Fresnel lens 3, or the transmittance of the Fresnel lens can be adjusted by changing the absorption filter 22 and the transmission characteristics of the absorption filter 22. Depending on the situation, a Fresnel lens may also be used as an absorption filter (2.2).

Moreover, without using the absorption filter 22, the absorption filter 2
A slide projector may be loaded with a slide having transmission characteristics similar to that of 2.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, and is applicable not only to ordinary black and white projection copying machines but also to color projection copying machines.

As described above, the copying machine according to the present invention eliminates unevenness in illuminance of a projected image, thereby making it possible to produce a copied image of uniform image quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining a conventional example, FIG. 2 is a schematic configuration diagram of a copying machine according to the present invention, and FIGS. 3 and 3 are an explanatory diagram for explaining the characteristics of a copying machine according to the present invention. It is an explanatory diagram.ノ; Document mounting table; Light source; Moving mirror; 7;
Lens g, 9; Fixed mirror 10; Photoreceptor /2; Secondary charging simultaneous exposure device /li; Transfer material

Claims (2)

[Claims] (1) A Fresnel lens is provided on the manuscript table, and a slide is projected onto the Fresnel lens using a slide projector;
In a copying machine that optically scans this projected image to obtain a copied image, there is an absorption between the vicinity of the Fresnel lens and the light source of the slide projector, the transmittance of which decreases as you move toward the optical axis of the lens of the slide projector. 1. A copying machine, characterized in that a filter is arranged, and the absorption filter corrects iris eclipse of the lens of the slide projector and unevenness in illuminance due to the cos' θ law. (2) The copying machine according to claim 1, wherein the Fresnel lens also serves as the absorption filter.