JPH01173023A - Slide copying machine - Google Patents

Abstract

PURPOSE:To increase the light quantity by allowing a slide transmission light to pass through a lens and to facilitate the correction of the light quantity by forming dots halftone liens on the surface as a filter provided in the vicinity of a lens used for a slide copying machine, and making density or a size in the center part of its dots halftone lines to be larger than that of its peripheral part. CONSTITUTION:By a slide copying machine, a light beam of a light source is projected onto a document placing table through a slide lens and a filter provided in the vicinity of its lens, and its projected image is copied. On the respective surfaces of filters 11-14 used for this slide copying machine, dots 21, 22 or halftone lines 23, 24 are formed. Also, density or a size in the center part of the dots 21, 22 or the halftone lines 23, 24 formed on the surface of the filters 11-14 is made larger than that of its peripheral part, by which even if the light quantity of the center part becomes larger than that of the peripheral part by allowing a slide transmission light to pass through the lens, the light quantity of the center part can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a slide copying machine that projects light transmitted through a slide onto a document table via a filter and a lens, and copies the projected image.

(b) Conventional technology Copying machines using electrophotography have become popular in recent years.
It is equipped with various functions depending on the purpose. One of these is a slide copying machine that can directly copy slide films. This apparatus includes a slide projector on the main body and a Fresnel lens on the document table, projects an image onto the Fresnel lens using the slide projector, and copies the projected image.

In such a slide copying machine, the slide projector is equipped with a convex lens for forming a projected image on a Fresnel lens.

Normally, such lenses have the characteristic that the amount of light is large in the center and less in the periphery, resulting in the periphery of the projected image being darker than the center. As shown in Japanese Unexamined Patent Publication No. 59-201036, a filter whose density is higher in the center than in the periphery is inserted into the light before image formation on the document table to cut the amount of light in the center and reduce the overall density. This ensures that an image with uniform brightness is formed.

(C) Problems to be Solved by the Invention However, conventional filters for correcting projection light have used intermediate tone filters in which the density increases toward the center. Since the reproducibility of halftones is poor, it is difficult to manufacture filters of the same quality, resulting in poor manufacturing yields and poor product accuracy. Furthermore, if the yield is poor, the cost of the filter increases, resulting in an increase in the cost of the copying machine itself.

In view of these drawbacks, it is an object of the present invention to provide a slide copying machine that can improve the filter yield and reduce the overall cost of the device by configuring the filter without halftones. .

(d) Means for Solving the Problems The slide copying machine of the present invention projects light from a light source onto a document table through a slide, a lens, and a filter provided near the lens, and copies the projected image. In the slide copying machine, the filter is a filter in which halftone dots are formed on the surface and the density or size of the halftone dots in the central part is larger than in the peripheral part, or a filter in which halftone dots are formed in the surface and It is characterized by using a filter in which the density or size of the mesh lines in the central part is larger than in the peripheral part.

(e) Function In the slide copying machine of the present invention, a filter having halftone dots or halftone lines with a large density in the center or a large size or thickness in the center is used, and the slide is passed through the filter. The transmitted light is projected onto the document table. Because of the halftone dots or halftone lines in the filter, the amount of transmitted light in the central portion is smaller than the amount of transmitted light in the peripheral portion. Therefore, even if the slide-transmitted light passes through the lens and the amount of light at the center is greater than the amount of light at the periphery, the amount of light at the center can be corrected by cutting the amount of light at the center.

<r> Embodiment FIGS. 1 to 4 are plan views of a projection light correction filter used in the Scade copying machine of the present invention.

In FIG. 1, halftone dots 21 are formed on a filter 11, and the size of the halftone dots 21 increases toward the center. Further, in FIG. 2, halftone dots 22 of the same size are formed at a higher density toward the center of the filter 12.

Furthermore, FIGS. 3 and 4 show mesh lines 23 and 24 formed on filters 13 and 14, respectively, and FIG. , and in FIG. 4, the mesh lines 24 are
It is a high-density version of .

It is no longer necessary to use halftones for these halftone dots 21, 22 and halftone lines 23, 24, and binary expressions of light and shade may be used.By configuring in this way, all filters 11 to 14 can be cut in the center. As the amount of light increases, the transmittance of the culm in the center decreases.

If such filters 11 to 14 are placed near the lens of the slide projector, the lens can cut off the amount of light in the center and correct the amount of light, making it possible to form a projected image with uniform brightness overall. can. Note that by arranging the filters 11 to 14 near the lens,
The pattern of halftone dots and halftone lines is not reflected in the projected image, and good projection can be performed.

Further, the amount of light cut (the body point, the size or density of the mesh lines) at the center of the filter is set according to the characteristics of the lens of the slide projector.

In other words, if the lens has a characteristic that the amount of light in the center part is large, the size or density of the halftone dots or halftone lines of the filters 11 to 14 should be made large in the center part, and the lens has a characteristic that the amount of light in the center part does not become too large. If so, filter 11
It is not necessary to make the size or density of the central part of the 14 halftone dots or halftone lines too large.

When duplicating these filters 11 to 14, the density only needs to be expressed in binary values as described above, so even when using silver halide photographic film, manufacturing conditions must be set differently than when producing halftones. This method has the advantage that it is easy to perform and the replication yield is also improved. Further, since only binary representation is required, there is an advantage that duplication can be performed by inexpensive means such as printing without using expensive silver halide film.

In this embodiment, the filters 11 to 14 are formed by changing the size and density of the halftone dots, or the thickness and density of the halftone lines, but the filters may be formed by combining these.

(g) Effects of the Invention In the slide copying machine of this invention, since the density of the filter is represented by a binary representation, there is no need to represent halftones, the filter accuracy is improved, and the manufacturing yield is also improved. . Therefore, manufacturing costs are reduced, and the cost of the slide copying machine itself can also be reduced.

[Brief explanation of the drawing]

1 to 4 are plan views of filters used in the slide copying machine of the present invention. 11-14-filter, 21.22-halftone dot, 23.24-halftone line.

Claims (1)

[Claims] (1) A slide copying machine that projects light from a light source onto a document table through a slide, a lens, and a filter provided near the lens, and copies the projected image, wherein the filter includes halftone dots on the surface. A filter that has halftone dots with a density or size larger in the center than the periphery, or a filter with halftone dots formed on the surface and a density or size larger in the center of the halftone dots than the periphery. A slide copying machine characterized by using a filter.