JP2002103779A - Anti-reproducing and antifalsifying sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the visually recognizably difficult properties of a latent image and emerge the latent image easily visually recognizably when reproduced. SOLUTION: In an antifalsifying sheet, on the surface of a sheet base material 2, either a back ground pattern or a latent image pattern consists of the aggregate of indeterminate multilateral figured dots P having pointed portions such as the combination of lozenges and rectangles under the state that the dots P are arranged in non-lined up state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copy forgery prevention sheet which enables a latent image to appear on a copy made by a copying machine to determine whether the copy is a copy.

[0002]

2. Description of the Related Art Conventionally, when a sheet printed on a special screen plate is copied, a latent image (warning character), which cannot be visually identified on the actual sheet, appears on the copy. The hidden word method which makes it possible to determine whether or not the screen is known is known. In this hidden word method, two types of screen plates having the same density but different numbers of lines are used, one of which is a latent image and the other is a background image. is there. In order to cope with a high-resolution copy machine, a background which does not appear when copying is printed on a screen plate having a screen frequency of 175 lines and a screen density of about 10%.

[0003]

As a method for easily producing such a screen plate, Japanese Patent Laid-Open No. 9-2 is disclosed.
There is a method disclosed in US Pat. However, the copy forgery prevention sheet prepared by this method is inferior in that the latent image on the actual sheet is difficult to visually recognize, and when observed very carefully, the latent image may be visually confirmed. . In particular, in the case where either the background or the latent image is simply a screen, that is, a so-called flat screen, the latent image can be easily identified with the naked eye, and there is a disadvantage that practical use is difficult.

The present invention solves these inconveniences and increases the difficulty in visually recognizing a latent image on a real sheet, and when the image is copied by a copying machine, the latent image clearly appears, and whether the image is a copy is determined. It is an object of the present invention to provide a copy forgery prevention sheet which makes it easier to recognize the above.

[0005]

In order to achieve the above object, a copy forgery prevention sheet according to claim 1 of the present invention comprises a background pattern for forming a background and a latent image on a sheet substrate surface. A latent image pattern to be formed is difficult to identify with the naked eye by a halftone screen, but is a copy forgery prevention sheet formed by applying the latent image pattern to the naked eye when copied with a copying machine, wherein the background The halftone screen of either the pattern or the latent image pattern is constituted by a set of halftone dots formed of an indefinite polygonal figure having a sharp portion.

In this specification, the term "indeterminate polygonal figure having a sharp part" means a figure formed by combining a plurality of ordinary polygons such as a triangle and a quadrangle, and in some cases, a part of the contour is curved. The polygons to be combined may be the same polygons, for example, squares, or different polygons, for example, a combination of triangles and squares, or a combination of two triangles and one square.

Further, in order to achieve the above-mentioned object, a copy forgery prevention sheet according to claim 2 of the present invention comprises:
On the sheet substrate surface, a background pattern for forming a background, and a latent image pattern for forming a latent image, by a halftone screen,
A copy forgery prevention sheet that is difficult to identify with the naked eye, but is provided so that the latent image pattern is identifiable with the naked eye when copied with a copy machine, and is a halftone dot of either the background pattern or the latent image pattern. The screen comprises a set of halftone dots made of an indefinite polygonal figure having a sharp part, and the halftone dots are arranged in a non-aligned state.

Further, in order to achieve the above-mentioned object, a copy forgery prevention sheet according to claim 3 of the present invention has a structure as described in claim 1 or 2, wherein the background pattern or latent image is provided. One of the halftone screens of the pattern has 196 lines and a density of 13%, and the other halftone screen has a number of lines of 65 and a density of 14 to 14%.
15%.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to FIGS. Here, FIG. 1 is a schematic plan view of the forgery prevention sheet, and FIG.
FIG. 3 is an enlarged explanatory diagram of the X portion, and FIGS. 3 to 5 are enlarged explanatory diagrams showing another embodiment relating to the shape of the halftone dot of the latent image pattern.

[0010] As shown in FIG.
Is a background pattern 3 for forming a background on the surface of the sheet base material 2.
And a latent image pattern 4 for forming a character "copy" as a latent image. Although not clear in FIG. 1, the background pattern 3 and the latent image pattern 4
Are the same color, for example, magenta printing, and are hardly distinguished from each other by the naked eye.

The halftone screen of the latent image pattern 4 is shown in FIG.
As shown in the enlarged view of FIG. 1, a halftone dot screen plate is formed by printing a set of halftone dots P of an indefinite polygonal figure having a sharp portion consisting of a rhombus and a rectangle.
They are arranged in a non-aligned state both vertically and horizontally. And
The halftone screen constituting the latent image pattern 4 has a screen ruling of 65 lines and a screen density of 15%.

On the other hand, the halftone screen constituting the background pattern 3 has 196 lines and a screen density of 13%. As described above, by setting the screen ruling of the background pattern 3 to 196, even if the screen density is 13%, the screen ruling is 175.
The size of a halftone dot having a line and screen density of about 10% can be obtained. That is, by increasing the screen ruling, the halftone dots of the background pattern 3 do not increase.
When copying with a copy machine, the background becomes difficult to appear.

The forgery prevention sheet 1 configured as described above
According to this, in the actual forgery prevention sheet 1, since the colors are the same, the difficulty of visually recognizing the latent image pattern 4 is increased, and the character of the latent image “copy” is visually recognized. It is difficult. In particular, by arranging the halftone dots P in a non-aligned state in both the vertical and horizontal directions, the sense of incongruity at the boundary between the background pattern 3 and the latent image pattern 4 is eliminated, and the difficulty of visually recognizing the character “copy” is reduced. improves.

On the other hand, in a copy of the forgery prevention sheet 1, even when a color copying machine is used, the background pattern 3 does not appear, and the latent image "copy" clearly appears, and the copy is visually recognized. Can be easily recognized.

Next, another embodiment relating to the shape of a halftone dot forming the latent image pattern 4 will be described. A halftone dot Q constituting the latent image pattern 4 shown in FIG. 3 is an irregular polygon figure having a pointed portion, which is a combination of three rectangles arranged such that two rectangles are orthogonal to one rectangle. Is a point. Further, the halftone dots R forming the latent image pattern 4 shown in FIG. 4 are halftone dots of an indefinite polygonal figure having a sharp portion formed by combining two rectangles in a cross shape. Further, the halftone dots S constituting the latent image pattern shown in FIG.
It is composed of halftone dots of an indefinite polygonal figure having a sharp part, which is obtained by combining two rhombuses, combining a rhombus and a trapezoid, or making a part of the contour of a figure formed by combining these rhombuses curved.

The present invention is not limited to the above-described embodiments. For example, the latent image is not limited to the character "copy". Further, the halftone screens of the background pattern 3 and the latent image pattern 4 may be configured to be opposite to each other, and the background pattern 3 may appear when copied, and the latent image may appear white. Further, it goes without saying that the shape of the halftone dot of the indefinite polygonal figure having the sharp part constituting the latent image pattern 3 is not limited to the above.

The composition of the background pattern 3 or the latent image pattern 4 in the copy forgery prevention sheet of the present invention is prepared collectively using graphic software on a computer. The halftone dots P, Q, R, and S of the indeterminate polygonal figure having the above-mentioned portions include various shapes including a combination of a plurality of ordinary polygons and, in some cases, a curved part of the contour, as described above. By building up samples and arranging many of them by image processing,
They form an aggregate.

[0018]

As described above, according to the forgery prevention sheet of claim 1 of the present invention, in the actual sheet,
Either the background pattern or the latent image pattern is constituted by a set of halftone dots of an indefinite polygonal figure having a pointed portion, so that the visibility of the latent image can be increased, and the latent image can be reproduced in a copy. This has the effect that visual recognition of is easy.

According to the forgery prevention sheet of the present invention, one of the background pattern and the latent image pattern is constituted by a set of halftone dots of an indefinite polygonal figure having a sharp part. Since the halftone dots are arranged in a non-aligned state, even if the other pattern is a so-called flat screen, there is no visual discomfort at the boundary between the two patterns, and it is possible to further enhance the difficulty in visually recognizing the latent image, and to improve the quality of the copy. Has an effect that visual recognition of a latent image is easy.

Further, according to the forgery prevention sheet of the present invention, one of the halftone screens of the background pattern and the latent image pattern has 196 lines and a density of 13%, and the other halftone screen has a density of 13%. Screen with 65 lines,
Since the density was set to 14 to 15%, in addition to the above-described effects, the halftone dot of the pattern having the number of lines of 196 and the density of 13% was set to 1
The size can be made substantially the same as a halftone dot having 75 lines and a density of 10%, which makes it harder to appear at the time of copying and has an effect that the visual recognition of the latent image becomes relatively easier.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing each pattern state of a forgery prevention sheet.

FIG. 2 is an enlarged explanatory view of a portion X in FIG. 1;

FIG. 3 is an enlarged explanatory view showing another embodiment relating to the shape of a halftone dot of a latent image pattern.

FIG. 4 is an enlarged explanatory view showing still another embodiment.

FIG. 5 is an enlarged explanatory view showing still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forgery prevention sheet 2 Sheet base material 3 Background pattern 4 Latent image pattern P, Q, R, S Halftone dot

Claims (3)

[Claims] 1. A halftone screen makes it difficult to identify a background pattern forming a background and a latent image pattern forming a latent image on a sheet base material surface with a halftone screen. A copy forgery prevention sheet in which an image pattern is applied so as to be identifiable to the naked eye, wherein the halftone screen of either the background pattern or the latent image pattern is formed of an indeterminate polygonal figure having a sharp portion. A sheet for preventing forgery of a copy, comprising a set of: 2. A background pattern forming a background and a latent image pattern forming a latent image on a sheet base material surface are difficult to discern by a halftone screen by a halftone screen. A copy forgery prevention sheet in which an image pattern is applied so as to be identifiable to the naked eye, wherein the halftone screen of either the background pattern or the latent image pattern is formed of an indeterminate polygonal figure having a sharp portion. Wherein the halftone dots are arranged in a non-aligned state. 3. A halftone screen having one of a background pattern and a latent image pattern is provided with 196 lines and a density of 13 dots.
%, The other halftone screen is 65 lines, density 1
The copy forgery prevention sheet according to claim 1 or 2, wherein the content is 4 to 15%.