JPH11301088A - Latent image-printed matter and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a superior forgery preventive effect by constituting a display surface with fine picture elements having a size to the recognized in individual colors, forming a gray level gradation image of an achromatic color under optional specific lighting of the picture elements, and making it into a display body to be a camouflage pattern of colors arranged at random under ordinary lighting. SOLUTION: In the case where an English character, e.g. 'H' is to be formed in a latent image, a display surface is cut into a minute square of the order of 0.5-1 mm in one side. In this next place, colors to be 0.4 in its density through a blue color filler are selectively disposed in an image part (a) of H, and colors to be 0.25 in its density through a blue filter are selectively disposed in a non- image part (b) at random before obtaining a display surface A. The blue color filter absorbs intensively light in a range (600-700 nm) of a specific wavelength, so that the density is reversed when a color is passed through a blue filter even in high density red and low density blue. So, even when a recognition of the latent image becomes difficult under ordinary lighting, an image of H can be observed in looking at the display body under a blue color filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display having an effect of preventing forgery and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally known technologies for forming an image into a latent image on a display surface and visualizing the image only under a specific condition use conditionally isochromatic coloring materials, photochromic coloring materials, and the like. There is a way to do that.

[0003] A conditionally isochromatic color material usually shows the same hue under illumination, but under a specific light source, two color materials having different hues are used in combination, and one is used as an image portion and the other is used as a non-image material. By placing it in the image part, it will be a single color under normal illumination, but under a specific light source, due to the difference in hue,
This forms a binary image.

A photochromic color material is a material whose hue changes when irradiated with a specific light source. A color material containing a photochromic material and a color material not containing a photochromic material are prepared so as to have the same hue under normal illumination. ,
It is possible to form a binary image under a specific light source.

In the multi-image display device and multi-image display method disclosed in Japanese Patent Application Laid-Open No. H5-262086, a plurality of images are shared on the same display surface, and an image that has been converted to a latent image by illumination of a specific color using a color filter or the like is used. A technique for extraction has already been filed.

[0006]

All of the prior arts have a small number of colors in a latent image state. In recent years, the progress of color reproduction technology has been remarkable, and although it does not have the above-mentioned optical special function, an image incorporated as a latent image in advance,
Adjustments can be made to negate during color duplication, and it is difficult to immediately identify this analog as a duplicate.

According to the present invention, a plurality of gradation images on a display surface are constituted as a camouflage meaningless image under normal illumination, and the gradation image is selectively displayed by a specific color illumination using a color filter or the like as necessary, and the color image is displayed. An object is to make color duplication difficult by combining with anti-duplication technology.

[0008]

In order to convert a gradation image into a latent image, the display surface is constituted by minute pixels of about 0.5 mm to 1 mm which can be recognized by a human, and the pixels are used. Forming a grayscale image of achromatic color under specific illumination, and selecting one of all chromatic colors under normal illumination corresponding to the density of one pixel for all pixels, Under a specific color illumination, a gray-scale image of an achromatic color is formed. Under a normal illumination, a display body having a camouflage pattern in which chromatic colors are randomly arranged and the display body are manufactured. Here, such a display body is referred to as a printed matter having a brocade (nishikiori) latent image.

Further, an image having a known function such as a conditionally isochromatic coloring material or a photochromic coloring material can be prepared by using the method disclosed in
By using the multiple image display body and the multiple image display method of No. 262086, the brocade latent image printed matter of the present invention and the gradation image by the method for producing the same can coexist on the same display surface, and a more advanced anti-counterfeit display body can be obtained. Can be made.

That is, in order to prevent the appearance of an image having a well-known condition-equal color material or the like which is a well-known function at the time of color duplication, it is necessary to correctly reproduce a brocade latent image arrangement area having abundant gradations and hues. On the other hand, if the brocade latent image arrangement area is to be correctly reproduced, an image having a conditionally conformal color material or the like appears, and it is easily found that the image is a forgery.

Further, since the color material used for the color reproduction is different from the color material used for the brocade latent image print of the present invention, even if it has the same color under normal illumination, it has different density under specific color illumination. , And under certain color illumination, the copy cannot have the function of a brocade latent image.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The brocade latent image printed matter of the present invention can make a gradation image visible under illumination of a specific color such as a color filter. Has abundant gradations and hues,
It is difficult to reproduce all hues and gradations, and the color reproduction cannot have the function of a brocade latent image.

As a first embodiment, as shown in FIG.
An embodiment in which is made a latent image will be described.

As shown in FIG. 1, the display surface is divided into small squares each having a side of about 0.5 mm to 1 mm. If one side is set too small, the individual colors cannot be recognized by human eyes, and the colors will be recognized as a mixed color composed of the colors of a plurality of rectangular regions. Therefore, the size of the minute square is about 0.5 mm, which allows humans to recognize individual colors. Conversely, if one side of the square is too large, the gradation image becomes coarse and the quality of the printed matter deteriorates. Therefore, it is preferable that the side of the minute square is about 0.5 mm to 1 mm.

As an example, a color having a density of 0.4 and a color having a density of 0.25 are selected as shown in Table 1 through a blue filter.

[0016]

[Table 1]

In Table 1, C indicates the dot area ratio of cyan in offset printing, Y indicates the dot area ratio of yellow, and M indicates the dot area ratio of magenta. Therefore, the color is represented by the superposition of the dot percentages of cyan, magenta, and yellow. Since the image obtained under specific color illumination, which is the final object of the present invention, is an achromatic gradation image, the colors used are achromatic in order to make the latent image more difficult to recognize under normal illumination. It is desirable to use a large number of bright chromatic colors that are far apart from each other on the hue circle in chromatics, rather than close colors. Cyan, magenta, yellow 3
When all the colors are superimposed, the color becomes achromatic, not the sharp chromatic color required for a brocade latent image. Thus, it can be seen that the colors in which the halftone dot area ratio of any one of cyan, magenta, and yellow is 0% are shown in Table 1.

In FIG. 1, a color having a density of 0.4 is randomly selected from Table 1 through a blue filter in an H image portion a, and a color having a density of 0.25 is selected through a blue filter in a non-image portion b. Are randomly selected and arranged from Table 1 as a display surface A.

Although human vision recognizes various colors under bright illumination, for example, under a blue filter, that is, under illumination that is dark and largely lacks a specific color component, it tends to recognize shades rather than colors.

FIG. 2 shows a spectral transmittance curve of the exemplified blue filter. As shown in FIG. 2, the blue filter strongly absorbs light in a specific wavelength range (600 nm to 700 nm). For example, even if red is high in density and blue is low in density, passing through a blue filter will reverse its density due to the transmission and absorption characteristics of the filter. As a result, it becomes difficult to recognize the latent image under normal illumination.

In this way, the display surface A described above becomes a meaningless image in which various colors are randomly arranged under normal illumination. However, when the display is viewed under the blue filter, the pixel is more recognizable than the color recognition. , The image portion a of H has a density of 0.4 and the non-image portion b of H has a density of 0.25, so that an image "H" can be observed as shown in FIG. .

Next, as a second embodiment, it is possible to convert a gradation image into a latent image as a brocade latent image. It is divided into 9 gradations in the range of 0.2 to 0.6 as shown in Table 2 through a blue filter exemplified in Example 1,
Purple, orange, and green color materials are used as colors corresponding to individual densities, and colors expressed by superimposing the dot area ratios are used.

[0023]

[Table 2]

The density of the gradation image to be formed into a latent image is made to correspond to a minute square pixel of about 0.5 mm to 1 mm on the divided display surface, and a plurality of colors corresponding to the density are shown in Table 2. By randomly selecting from the table, under normal lighting, various colors are randomly arranged. But,
When passing through the blue filter, the colors arranged in the individual pixels display meaningful gradation images according to the relationship between the density under the blue filter in Table 2 and the colors under normal illumination.

In the third embodiment, this brocade latent image can be used in combination with a conditionally isochromatic coloring material. That is, as shown in the display surface B of FIG. 3, the display surface is divided into minute squares each having a side of about 0.5 mm to 1 mm, and the minute area is divided into a brocade latent image area c and a conditionally isochromatic coloring material. The arrangement areas d are alternately arranged.

On the display surface B of FIG. 3, the image shown in the first or second embodiment is arranged in each pixel of the brocade latent image area c. On the other hand, the image part e and the non-image part f of the alphabetical letter "E", which is a binary image, are assigned to the conditionally isochromatic color material arrangement area d as shown on the display surface C in FIG. As an example, the conditionally isochromatic color material refers to a pair of color materials that have the same color under normal illumination but have different colors under the A light source (orange). Are arranged in the image portion e and the non-image portion f of the binary image, respectively.
Under normal illumination, all the pixels arranged in the conditionally isochromatic color material arrangement area d have the same color. However, when the A light source or color copy is performed, the color difference between the pair of color materials becomes remarkable. A binary image “E” as in FIG. 4 appears.

In the display surface B thus produced, under normal illumination, the brocade latent image region c is in a state in which various colors are arranged randomly, and the conditionally isochromatic color material arrangement region d is a pair of colors. Although the material shows the same color and does not display meaningful images in both areas, the latent image of Example 1 or Example 2 appears under a blue filter, and the latent image is formed by color copying the display. The binary image “E” appears.

In general color copying, it is possible to duplicate conditionally isochromatic color materials to substantially the same color by adjusting the ejection amounts of cyan, magenta, and yellow color materials by greatly changing them. However, in order to reproduce the conditionally isochromatic color material in the color copy of the display body B of the third embodiment in substantially the same color as the color of the original display body, the ejection amounts of the cyan, magenta, and yellow color materials must be reduced. If it is adjusted, it becomes impossible to correctly reproduce all the rich tones and colors arranged in the brocade latent image area, and the latent image of the first or second embodiment will not appear under the blue filter. On the other hand, if the color arranged in the brocade latent image area is to be reproduced correctly, the color matching material cannot be reproduced correctly. E "appears. As a result, it is easy to determine that the display B is a copy by color copying.

As a fourth embodiment, the conditionally isotropic color material arrangement region d of the third embodiment has a different color under normal illumination.
It is also effective to use a color material having the same color under the blue filter described above. That is, under normal illumination, the conditionally isochromatic arrangement region d displays a binary image, and the brocade latent image region c becomes a meaningless image in which colors are randomly arranged. The paired colors of the arrangement area d have the same color, the binary image disappears, and the gradation image of the brocade latent image area c appears.

Note that the binary image of the conditionally isochromatic color material arrangement area d displayed under normal illumination is a brocade latent image area c.
It is also effective for camouflaging the latent image formation.

As a fifth embodiment, as shown in a display surface D in FIG. 5, the display surface is divided into minute regular hexagons each having a side of about 0.5 mm, and a brocade latent image region c, a conditionally uniform color material arrangement region d, three regions of the conditionally-equivalent color material arrangement region d 'are arranged, and one printing medium has three functions at the same time. These regions are repeated for every three regular hexagons. As shown in FIG. 6, the phase shift of the conditionally isochromatic color material arrangement region d with respect to the brocade latent image region c is 3 periods in the direction of the arrow. One-third, as shown in FIG.
Is 2/3 of the period in the direction of the arrow. When the phase moves by one cycle, the phase returns to the brocade latent image area c. A pair of color materials showing the same color under normal illumination in the conditionally equal colorant arrangement region d, but different colors under specific color illumination, and a normal illumination in the conditionally uniform colorant arrangement region d ' Although a different color is shown below, a pair of color materials showing the same color under specific color illumination are arranged. In the printed matter produced in this manner, an image due to the conditionally-equivalent color material arrangement region d 'is observed under normal illumination. However, this image disappears and a brocade latent image appears due to the specific color filter. In addition, an image of the conditionally isochromatic color material c appears in the color reproduction, and a forgery prevention effect can be imparted.

[0032]

According to the present invention, it is possible to produce a functional display member capable of forming a latent image having a gradation in a camouflage pattern and visualizing the gradation image by illumination of a specific color. In addition, by arranging a conditionally isochromatic coloring material or the like between the brocade latent image areas, it becomes an effective forgery prevention means for color copying. That is, by adjusting the ejection amounts of cyan, magenta, and yellow of a color copier, if a pair of conditional isometric color materials is to be reproduced correctly, a camouflage pattern having abundant gradations and colors is correctly reproduced. Therefore, the gradation image cannot be visualized under the specific color illumination from the camouflage pattern by the duplicate. Conversely, if the camouflage pattern is correctly reproduced, the pair of conditional isometric color materials will not be reproduced correctly, and it will be easily found to be a counterfeit, and can be used for authenticity determination.

[Brief description of the drawings]

FIG. 1 is a diagram in which an English letter H is made a latent image as a brocade latent image.

FIG. 2 is a diagram of a spectral reflectance curve of a blue filter.

FIG. 3 is a diagram in which a printed matter shares a brocade latent image area and a conditionally isochromatic color material arrangement area.

FIG. 4 is a diagram in which an alphabetic character E is made a latent image in a conditionally isochromatic color material arrangement area.

FIG. 5 is a diagram in which a printed matter shares a brocade latent image area and two conditionally isochromatic color material arrangement areas.

FIG. 6 shows a single printed matter sharing a brocade latent image area and two conditionally-equivalent color material arrangement areas, and the conditionally-equivalent color material arrangement area d has a phase of 3 with respect to the brocade latent image area c.
The figure which showed that it shifted by one part.

FIG. 7 shows a single printed matter sharing a brocade latent image area and two conditionally-equivalent color material arrangement areas, and the conditionally-equivalent color material arrangement area d ′ has a periodic phase with respect to the brocade latent image area c. The figure which showed that it was shifted by 2/3.

[Explanation of symbols]

 a H-shaped image part b H-shaped non-image part c Brocade latent image arrangement area d Conditional isochromatic coloring material arrangement area d 'Condition isochromatic coloring material arrangement area e E-shaped image part f E-shaped Non-image area A display surface B display surface C display surface D display surface

Claims (8)

[Claims] The display surface is composed of minute pixels having a size capable of recognizing individual colors, and these pixels form an achromatic gradation image of an achromatic color under illumination of an arbitrary specific color. On the other hand, for all pixels, randomly selecting one chromatic color from among all chromatic colors under normal illumination corresponding to the density under the specific color illumination,
Under the specific color illumination, an achromatic gradation image is formed,
A display that has a camouflage pattern in which chromatic colors are randomly arranged under normal lighting. 2. The display surface is composed of minute pixels of a size capable of recognizing individual colors, and these pixels form an achromatic gradation image of an achromatic color under illumination of an arbitrary specific color. On the other hand, for all pixels, randomly selecting one chromatic color from among all chromatic colors under normal illumination corresponding to the density under the specific color illumination,
Under the specific color illumination, an achromatic gradation image is formed,
A method for producing a display body that becomes a camouflage pattern in which chromatic colors are randomly arranged under normal lighting. 3. The display surface is composed of minute pixels having a size capable of recognizing individual colors, and the pixels are extracted at a constant cycle. The extracted pixels are used to illuminate an achromatic color under illumination of an arbitrary specific color. Is formed, and for one pixel, it is extracted that one chromatic color is randomly selected from all chromatic colors under normal illumination corresponding to the density under the specific color illumination. For all pixels,
Further, all the remaining pixels are classified in the same cycle and the same phase as the above-described cycle, and for each pixel having the same cycle and the same phase, using these pixels, a specific color illumination different from the above-described specific color illumination. An achromatic color gradation image is formed below, and one chromatic color is randomly selected from all chromatic colors under normal illumination corresponding to the density under the specific color illumination for one pixel. Is performed for all the phases and all the pixels, and one achromatic gradation image is formed for each of the above-described specific color illuminations. However, under normal illumination, the camouflage in which chromatic colors are randomly arranged A display body having a plurality of gradation latent images forming a pattern. 4. The display surface is composed of minute pixels having a size capable of recognizing individual colors, and the pixels are extracted at a constant cycle, and the extracted pixels are used to illuminate achromatic colors under illumination of an arbitrary specific color. Is formed, and for one pixel, it is extracted that one chromatic color is randomly selected from all chromatic colors under normal illumination corresponding to the density under the specific color illumination. For all pixels,
Further, all the remaining pixels are classified in the same cycle and the same phase as the above-described cycle, and for each pixel having the same cycle and the same phase, using these pixels, a specific color illumination different from the above-described specific color illumination. An achromatic color gradation image is formed below, and one chromatic color is randomly selected from all chromatic colors under normal illumination corresponding to the density under the specific color illumination for one pixel. Is performed for all the phases and all the pixels, and one achromatic gradation image is formed for each of the above-described specific color illuminations. However, under normal illumination, the camouflage in which chromatic colors are randomly arranged A method for manufacturing a display body having a plurality of latent images forming a pattern. 5. The display surface is composed of minute pixels having a size capable of recognizing each color, and the pixels are divided into two regions by extracting every other pixel, and pixels in one region are used. To form an achromatic color gradation image under any specific color illumination, and randomly select one pixel from all chromatic colors under normal illumination corresponding to the density under the specific color illumination. A single chromatic color is selected for all pixels in one area, and a pair of colors having the same color under normal illumination but different colors under different light sources are binary-coded in the other area. Arranged in the image part and non-image part of the image, under normal illumination, various chromatic colors are randomly arranged in a camouflage pattern, but under the specific color illumination, an achromatic gradation image is formed and different A display object where a binary image appears under a light source . 6. The display surface is composed of minute pixels having a size capable of recognizing individual colors, and the pixels are divided into two regions by extracting every other pixel, and pixels in one region are used. To form an achromatic color gradation image under any specific color illumination, and randomly select one pixel from all chromatic colors under normal illumination corresponding to the density under the specific color illumination. A single chromatic color is selected for all pixels in one area, and a pair of colors having the same color under normal illumination but different colors under different light sources are binary-coded in the other area. Arranged in the image part and non-image part of the image, under normal illumination, various chromatic colors are randomly arranged in a camouflage pattern, but under the specific color illumination, an achromatic gradation image is formed and different A display object where a binary image appears under a light source Method of manufacturing. 7. The display surface is constituted by minute pixels having a size capable of recognizing individual colors, and the pixels are divided into two regions by extracting every other pixel two-dimensionally. A gray-scale image of achromatic color is formed under any specific color illumination using the pixels of one pixel, and for one pixel, any chromatic color under normal illumination corresponding to the density under the specific color illumination One chromatic color is randomly selected from among all the pixels in one area, and the other area has the same color under the specific color illumination described above, but a different color under normal illumination. A pair of colors is arranged in the image portion and the non-image portion of the binary image, and the binary image is displayed under normal illumination. However, the binary image disappears under the specific color illumination, and the achromatic color gradation is displayed. A display that forms a toned image. 8. A display surface is constituted by minute pixels having a size capable of recognizing individual colors, and the pixels are divided into two regions by extracting every other pixel two-dimensionally. A gray-scale image of achromatic color is formed under any specific color illumination using the pixels of one pixel, and for one pixel, any chromatic color under normal illumination corresponding to the density under the specific color illumination One chromatic color is randomly selected from among all the pixels in one area, and the other area has the same color under the specific color illumination described above, but a different color under normal illumination. A pair of colors is arranged in the image portion and the non-image portion of the binary image, and the binary image is displayed under normal illumination. However, the binary image disappears under the specific color illumination, and the achromatic color gradation is displayed. A method for producing a display member for forming a toned image.