JPS5814126A - Slit illumination device - Google Patents

Abstract

PURPOSE:To compensate the light intensity distribution in a slit region to be irradiated, by directing the light from a light source toward the peripheral part in the longitudinal direction of the slit region by a side mirror to increase the quantity of light in the peripheral part. CONSTITUTION:A side mirror 8 is provided for the purpose of utilizing effectively a part (indicated by oblique lines), which is at the outside of a slit region W, of the luminous flux which goes from a light source 1 in the longitudinal direction of the slit region. The side mirror 8 is bent into mirrors 8a and 8b so that the luminous flux from each of plural regions, into which the part indicated by oblique lines is divided, is reflected toward the slit region, and luminous fluxes reflected by respective reflecting parts 8a and 8b are irradiated not to the center but to the peripheral part in the longitudinal direction of the slit.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slit illumination device for copying machines, facsimile machines, etc.

As a light source for document illumination in a slit exposure type copying machine, a rod-shaped light source with a length approximately equal to the width of the document to be copied is often used. Because it is long and thin, it has the disadvantage of being weak against shock. For this rod-shaped light source,
76, Japanese Patent Publication No. 56-2956, etc., a point-emitting light source is used.

In the system disclosed in Japanese Patent Publication No. 53-41976, a light beam from a point-emitting light source is reflected by a parabolic mirror to form a parallel beam of light, which is expanded to a width equivalent to the width of the original, and the parabolic mirror illuminates the surface of the original in the form of a slit. Uniform illuminance can be obtained. However, since a parabolic mirror or a parabolic mirror is used, it is difficult to make the device compact, especially in the vertical direction. On the other hand, special public official Sho 56-2956-1! The system disclosed in the publication uses a compound eye imaging system in which a plurality of focusing optical fiber elements (trade name SELFOC) are arranged in an array as an imaging element to make the copying machine more compact, and uses a point-emitting light source. The inner surface of a flat casing in which the light source is placed is formed into a reflecting mirror, and the surface of the document is illuminated in a manner similar to a so-called ride guide that sequentially reflects and transfers the light beam from the light source. However, the illuminance distribution in the longitudinal direction of the slit region irradiated by this method cannot necessarily be made uniform. This is because the aim is simply to achieve a superimposition effect due to multiple reflections. In general, in an illumination system that uses a point-emitting light source at the longitudinal center of the slit, the direct light causes the light intensity to be higher at the center than at the longitudinal periphery of the slit area to be irradiated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an illumination device that uses a point-emitting light source, compensates for the light intensity distribution of a slit region to be illuminated, and is suitable for a compact copying machine that uses a compound eye imaging system.

This purpose is achieved by directing the light from the light source to the periphery in the longitudinal direction of the slit region using a side mirror or rear mirror having a predetermined angle, thereby increasing the amount of light in the periphery.

Hereinafter, the present invention will be described in detail using the accompanying drawings.

FIG. 1 is a schematic diagram of a copying machine using the present invention.

The male rear mirror 6 is a plane mirror, and the light source 1 is converged in the vicinity of the slit area 5 to be irradiated on the N internal reflecting mirror 2a of the document surface 4. 2a may be an elliptical reflecting mirror or a multi-plane obtuse mirror. 8a and 8b are side mirrors to be described later. The slit area 5 on the document surface 4 is projected in the form of a slit onto the movable photoreceptor 7 by the compound eye imaging system B.

FIG. 2 is a diagram showing the relative relationship between the light source 1 and the slit area 5 on the document surface 4. As shown in FIG. As shown in the figure, the light intensity distribution in the slit area 5 due to the direct light from the light source 1 is high at the center in the longitudinal direction of the slit where the light source is set, and is low at the periphery.

Here, the width W of the light source 10 is 50+% of the width W of the slit area 50.
It is as follows. Although one light source 1 is provided at the center in the longitudinal direction of the slit, a plurality of light sources 1 may be additionally provided in a straight line parallel to the longitudinal direction of the slit.

When added together, the light intensity distribution becomes as shown in FIG. 2, with the light intensity being lower at the periphery than at the center of the slit area.

FIG. 4 is a diagram of an embodiment of the present invention.

In Fig. 4, in order to effectively utilize the part of the light beam directed from the light source 1 in the longitudinal direction of the slit area (the shaded area) that protrudes outside the slit area W, we use a side mirror. Divide into multiple areas according to
The side mirrors 8 are each 8a, ! so as to reflect the light flux from each region toward the slit region. 3b, so that the light beam reflected by each reflecting portion illuminates not the central portion in the longitudinal direction of the slit region but the peripheral portion.

Number of reflective parts of side mirror 8, angle and length of each reflective part (g) The height is determined by considering the size of the light source and the light distribution characteristics.

In Fig. 4, the light flux up to the half-field angle θ1 directly illuminates the slit area, and the light flux between the half-field angles θ1 and θ2, and the light flux between the half-field angles θ2 and θ3 are reflected by the side mirrors 8a and 8b, respectively, to the slit area. Irradiate the longitudinal periphery.

The periphery of the slit region in the longitudinal direction is also irradiated with respect to the reflected light to compensate for the light intensity distribution due to the direct light in the longitudinal direction of the slit.

Here, the reflective surface of the rear mirror 2b is parallel to the longitudinal direction of the slit, that is, it is cylindrical, but as a different embodiment, as shown in FIG. They may be provided obliquely, such as 9g and 9b, so as to irradiate the peripheral area of the area. Note that the slope portion may be a flat surface or a curved surface. By using such a side mirror or the like, the difference in the light intensity distribution in the longitudinal direction of the slit area on the document surface between the center and the periphery is reduced, as shown in FIG. In FIG. 6, the solid line represents a system in which the present invention is used, and the broken line represents a system in which the present invention is not used.

As described above, according to the present invention, it is possible to provide a slit illumination device for a copying machine or the like that uses a point-emitting light source to compensate for the light intensity distribution in the longitudinal direction of a slit area on a document surface.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a copying machine using the present invention, and FIG. 2 shows the relative distance s'111 between the light source and the slit area on the document surface. Fig. 3 is a blueprint diagram of the light source, Fig. 4 is an embodiment of the present invention and a diagram relating to a side mirror, Fig. 5 is an embodiment of the invention and a diagram relating to a front mirror, an internal reflecting mirror, and 2b is a front mirror. , 6 is a plane mirror, 4 is a document surface, 5 is a slit area,
6 is a compound eye imaging system, 7 is a movable photoreceptor, 8a and 13b are side mirrors, and 9a and 9b are sloped portions of the front mirror. 153-

Claims (2)

[Claims] (1) A plurality of light sources according to the orientation characteristics in the longitudinal direction of the slit, which are fixed at a predetermined distance from the slit area to be illuminated and substantially at the center in the longitudinal direction of the slit, and have a width W of 50 inches or less than the longitudinal width W of the slit. and a side mirror having a plurality of reflective surfaces to reflect the light-emitting regions divided into individual light-emitting regions to the periphery in the longitudinal direction of the region surrounding the slit region, and a light intensity distribution of direct light from the light source in the slit region. A slit lighting device characterized by compensating for. (2) The slit illumination device according to claim 1, wherein the back surface of the reflective shade with respect to the light source has a reflective surface oblique to the longitudinal direction of the slit.