JPH0332794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for camouflaging a latent image provided on a printed matter to prevent copying.

In order to prevent important documents such as securities from being forged by copying machines, a latent image such as "VOID" is printed on the surface of the paper, and when the paper is run through a copying machine, the latent image is distinguished from the background part. It is known that it can be visually recognized. However, in this case, there is a difference in size between the halftone dots that make up the latent image and the background, and one halftone dot cannot be reproduced by a copying machine, but the other halftone dot is of a size that can be reproduced by a copying machine, and after copying, The existence of the latent image is confirmed by the difference in brightness between the two. In order to prevent the latent image from being recognized with the naked eye before copying, there is a method of providing camouflage over both the latent image and the background, but since both the latent image and the background are a combination of points with the same shape, If the size difference between the dots is not extreme, the latent image will not appear clearly after copying, but if the dot size difference is made too extreme, the latent image will be visible to the naked eye even if a camouflage is installed. and,
There were also limitations in the placement of the top camouflage and the color tone, making it difficult to obtain good-looking printed matter.

In the present invention, the latent image is made up of halftone dots and the background is made up of lines, and by overprinting a pattern that interferes with the lines and forms a moiré pattern from the upper surface of these lines, the latent image is sufficiently covered. Moreover, the present invention provides a camouflage method in which the latent image clearly appears after copying, making it obvious at a glance that it is a copy.

Next, to explain based on the drawing, there is a latent image 3 labeled "COPY" consisting of 150 lines and 10% dots, and a background 4 consisting of 50 to 60 lines and 10% dots on the white background around the latent image. Dark color printing is performed on the surface of the paper 1 using a latent image plate 2 equipped with a latent image plate 2. Then, using an overprint plate 5 having a waveform pattern 6 made of parallel lines that forms a moiré pattern 7 when they interfere with the parallel lines of the background 4, overprinting in a light color that cannot be reproduced by a copying machine is applied to the surface of the paper. to camouflage the latent image 3.

The surface of the printed matter obtained in this way has a moiré pattern 7 that confuses the naked eye, making it difficult to identify the latent image 3 at all. 6 is not reproduced, but only the background 4 is reproduced, and as a result, the latent image 3 is recognized as being distinguished from the background 4.

In other words, when the waveform pattern 6 is overprinted on the surface of the paper 1, it interferes with the lines of the underprinted background 4 and a moire pattern 7 is formed, so that only this moire pattern is printed on the surface of the paper. Neither the visible latent image nor the background is visible, and the existence of the latent image is never discovered. However, if you put it on a copy machine, it will be 150 lines 10
The latent image 3 consisting of % halftone dots is not reproduced and therefore appears white, whereas the background 4 consisting of 50 to 60 lines and 10% lines is reproduced and appears as a dark color.
Furthermore, since the overprinted waveform pattern 6 is not reproduced in a light color, only the difference in density between the halftone dots and the parallel lines becomes noticeable, and the latent image 3 is clearly identified, making it obvious that it is a copy.

As described above, the present invention is characterized in that the pattern 6 overprinted from the upper surface of the latent image 3 does not itself have a moire pattern, but rather interferes with the parallel lines of the background 4 to form a moire pattern. . The line that interfered with the pattern 6 loses its unique shape, so that the boundary with the halftone dot becomes unclear, and the latent image 3 is immersed in the moiré pattern 7 and is of such a size that it cannot be seen.

However, in the present invention, since a method is used in which underprinting is performed using the latent image plate 2 and then overprinting is performed using the overprinting plate 5, the obtained printed matter is printed on paper as shown in the fourth figure. The ink layer B of the pattern is superimposed on the upper surface of the latent image and the background ink layer A on the upper surface of 1. Therefore, the ink layer B
Since the color tone can be selected from a wide variety, it is possible to obtain a color pattern depending on the purpose and appearance of the printed material, and also to create a pattern 6.
By changing the shape and angle of the moire pattern, a variety of moiré patterns can be formed, which has the practical benefit of producing any decorative effect on printed materials. is extremely advantageous.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a latent image plate used for carrying out the present invention, Fig. 2 is a plan view of an overprint plate, and Fig. 3 is a plan view of an overprint plate.
The figure is a plan view of a printed matter obtained by the method of the present invention, FIG. 4 is a partially enlarged sectional view of FIG. 3, and FIG. 5 is a plan view of a copy of the printed matter. 1 is paper, 2 is latent image plate, 3 is latent image, 4 is background,
5 is an overprint version, 6 is a pattern, and 7 is a moiré pattern.

Claims (1)

[Claims] 1 Printing is performed on the surface of paper using a latent image plate that has a latent image consisting of halftone dots that cannot be reproduced by a copying machine and a background consisting of lines that are reproduced by a copying machine, and then printing is performed on the surface of the paper using a latent image plate that has a latent image made up of halftone dots that cannot be reproduced by a copying machine, and a background that is made up of parallel lines that is reproduced by a copying machine. A method for camouflaging a latent image for preventing copying in printed matter, using an overprint plate with a pattern that forms a moiré pattern to overprint a light color on the paper surface that cannot be reproduced by a copying machine.