JP2011148129A - Printed material having latent image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed material in which three images can be viewed in different observation conditions such as in a diffused light region and a normally reflected light region under a visible light source and further under an infrared light source by using a precise dot structure. <P>SOLUTION: The printed material has a print area on at least part of a substrate, in which images are formed by use of three dots. A plurality of first dots are arranged by use of a material free from infrared ray absorbing pigment to thereby form a visible image of continuous gradation, the second dots are arranged inside the first dots by use of a material containing infrared ray absorbing pigment to form a first latent image, and the third dots are arranged inside the second dots by use of a material which is changed in chrominance ΔE with the second dot by a predetermined value by changing the observation angle from the diffused light region to the normally reflected light region relative to an illuminating light source at a fixed position to form a second latent image. The first dots, the second dots and the third dots are formed so that their colors are matched to each other in the diffused light region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a printed matter having a latent image that is applied to banknotes, passports, securities, product tags, various certificates and the like for prevention of counterfeiting and duplication.

  In recent years, counterfeit printed products such as banknotes, passports, and securities have become a serious problem due to high performance and high image quality of copiers. For this reason, functional inks that are difficult to reproduce color, gloss, light emission or the like with a copying machine have been conventionally used for precious printed matter. Functional inks include metallic glossy inks such as gold ink, silver ink or pearl ink, and infrared absorbing inks that exhibit absorption characteristics in the infrared region. When authenticating a printed matter using infrared absorbing ink, an identification device such as an infrared camera is required. Therefore, it is difficult to visually determine the infrared absorbing ink printing portion without an identification device. On the other hand, when authenticating printed matter using metallic gloss ink, it is only necessary to pay attention to changes in gloss and color, and anyone can easily determine visually.

  Therefore, the present applicant uses either metallic glossy ink for the background image portion or the latent image portion, and the other using infrared absorbing ink or infrared transmitting ink, and prints the same color under a visible light source. Thus, a printed matter in which the latent image can be visually recognized by changing the observation angle is disclosed (see, for example, Patent Document 1).

  In addition, the applicant of the present invention requires an appraisal device such as an infrared camera for authenticity determination, but by using a special halftone dot configuration, it is very difficult to reproduce with the current photoengraving device, A halftone print having an excellent anti-counterfeit effect is disclosed (see, for example, Patent Document 2).

  Patent Document 2 filed earlier by the present applicant is a printed material that forms a gradation image by arranging a plurality of two regions, and the second region is surrounded by the first region. The second region is composed of a region 2a composed of black ink containing an infrared absorbing dye, and a region 2b composed of a black system using ink not containing an infrared absorbing pigment, and the first region and The region 2b uses three primary color inks of cyan (C), magenta (M), and yellow (Y) that are used in general commercial printing.

  The printed matter described in Patent Document 2 not only exhibits the effect of preventing duplication due to a special halftone dot configuration, but also forms a latent image in the area 2a composed of black ink containing an infrared absorbing dye. Therefore, when observing with an appraisal device such as an infrared camera, an image different from the gradation image observed under a visible light source becomes visible.

  As described above, the printed matter described in Patent Document 2 uses black ink containing an infrared absorbing dye in the region 2a constituting the latent image in order to make the image visible under an infrared light source. Since the 2b region is also configured in black so as to be the same color as the 2a region, the printed matter itself has a relatively low brightness (high density) design.

  Therefore, the present applicant further discloses a forgery prevention printed matter using a metal material instead of black ink containing an infrared absorbing dye in a region for forming a latent image (for example, Patent Document 3). reference).

  Similar to the printed material described in Patent Document 2, the printed material described in Patent Document 3 includes a gradation image that is visible under a visible light source and a latent image that is visible under infrared light. By using a metal material in a region for constructing an image, the design of relatively low brightness (high density) in Patent Document 2 is eliminated.

  By using a metal material, depending on the material and color, it may cause a metallic luster. Therefore, for the purpose of suppressing the metallic luster, it is colorless and transparent on the metallic material in the area constituting the latent image. Printing with a mat layer or white ink overlaid.

JP 2007-152805 A Japanese Patent No. 3544536 JP 2008-132601 A

  However, the printed matter disclosed in Patent Document 1 uses a metallic gloss ink to make the latent image visible by changing the observation angle, but the configuration is based on a simple solid print. In addition, the design is limited to a uniform design (with few gradations), and the anti-counterfeit effect is not so advanced.

  In addition, since the printed matter according to Patent Document 2 and Patent Document 3 uses a dense halftone dot configuration, it is difficult to reproduce with a photoengraving device, and an image under a visible light source and an image under an infrared light source are clear. Although it is a printed matter with a high anti-counterfeiting effect that can be confirmed by switching to a non-counterfeit, it requires an appraisal device such as an infrared camera. There was a problem that false discrimination could not be performed. Therefore, there is a demand for anti-counterfeit printed matter to which a technique capable of easily determining authenticity by visual observation without using a special identification device.

  The present invention aims to solve such a conventional problem. By using a dense halftone dot configuration, it is difficult to reproduce and the first can be easily achieved by changing the observation angle. The latent image can be confirmed, and further, the second latent image can be confirmed by an appraisal device such as an infrared camera, so proper authenticity can be determined under different conditions. The purpose is to propose a simple printed matter.

  In the present invention, a print area is formed on at least a part of a substrate, and a continuous tone visible image and two latent image images are formed in the print area by three types of halftone dots, and the observation conditions are different. In this way, each image can be visually recognized, and a plurality of first halftone dots are arranged using a material that does not contain an infrared absorbing dye, thereby forming a continuous tone visible image. The halftone dots are superposed in the first halftone dot by a material containing an infrared absorbing dye to form a continuous tone first latent image, and the third halftone dot is an illumination light source at a fixed position. By changing the observation angle from the diffuse light region to the regular reflection light region, the color difference ΔE with the second halftone dot is superimposed on the second halftone dot by a material that changes by a predetermined value. A continuous latent second latent image is formed, and the first halftone dot, the second halftone dot, and the third halftone dot are acceptable. By forming the same color in the diffused light region under the light source, the printed material has a visible image visible in the diffused light region, the first latent image pattern is observed under the infrared light source, and the illumination light source at a fixed position. On the other hand, the second latent image pattern can be visually recognized by changing the observation angle from the diffuse light region to the regular reflection light region.

  In the present invention, a print area is formed on at least a part of a substrate, and a continuous tone visible image and two latent image images are formed in the print area by three types of halftone dots, and the observation conditions are different. Each of the images is a printed matter that can be visually recognized, and at least the area corresponding to the printing area of the base material changes the observation angle with respect to the illumination light source at a fixed position from the diffuse light area to the regular reflection light area. It is made of a material that changes color, does not contain infrared absorbing dye on the substrate, and changes the observation angle of the substrate with respect to the illumination light source at a fixed position from the diffused light region to the regular reflected light region. By doing so, a concealing region is formed using a concealing material that does not change color, and the concealing region consists of a region where a concealing material that conceals the substrate and a region where no concealing material that exposes part of the substrate is applied, On the area where the concealing material is applied, the first A halftone dot and a second halftone dot are arranged, and a plurality of first halftone dots are arranged using a material that does not contain an infrared absorbing dye, thereby forming a continuous tone visible image. Is formed of a material containing an infrared absorbing dye so as to have a part of a blank area in the first halftone dot to form a continuous tone first latent image, and a second halftone dot blank area. And the region where the concealment material is not applied in the concealment region is arranged at the same position, so that a second latent image of continuous tone is formed by the third halftone dot formed by exposing the base material. By forming the first halftone dot, the second halftone dot, and the third halftone dot so as to have the same color in the diffused light region under the visible light source, the printed matter can visually recognize the visible image in the diffused light region. The first latent image pattern is observed under an infrared light source and observed against a fixed illumination light source By changing the degree of light from the diffuse light region to the regular reflection light region, the color difference ΔE between the second halftone dot and the third halftone dot changes by a predetermined value, and the second latent image pattern can be visually recognized. It is a printed matter having a characteristic latent image.

  Further, the printed matter having a latent image of the present invention is characterized in that the blank area of the second halftone dot and the area where the concealment material is not applied in the concealment area have the same shape and size.

  The second halftone dot of the present invention is smaller than the constant halftone dot diameter set in the first halftone dot, and the third halftone dot is a constant halftone dot set in the second halftone dot. It is smaller than the diameter.

  In addition, the material in which the color difference ΔE with the second halftone dot of the present invention changes by a predetermined value can be diffused by changing the observation angle from the diffuse light region to the regular reflection light region with respect to the illumination light source at a fixed position. The material is characterized in that the color difference ΔE with the second halftone dot in the regular reflection light region changes by 5 or more with respect to the color difference ΔE with the second halftone dot in the light region.

  Further, the material in which the color difference ΔE with the second halftone dot of the present invention changes by a predetermined value is a glittering material, and the glittering material is any material of metal powder ink, foil, metal, or metallic glossy film. It is characterized by being.

  The material containing the infrared absorbing dye of the present invention is a colored ink containing a material having at least one wavelength peak in the infrared region.

  Further, the material that does not contain the infrared absorbing dye of the present invention is a colored ink of cyan, magenta and yellow or a single color special color ink.

  When the printed matter having the latent image of the present invention is observed in a diffused light region under a visible light source, the visible image can be visually recognized, and the second latent image can be visually recognized by observing the printed matter at an angle. Since the first latent image can be visually recognized by an appraisal device such as an infrared camera, three different images can appear by changing the observation conditions.

  In addition, as described above, since the printed matter having the latent image of the present invention can cause two latent image images to appear under different conditions, a simple authenticity determination and an identification device are used. It is possible to perform two kinds of true / false discrimination called true / false discrimination. Therefore, authenticity determination can be performed in accordance with the environment and situation in which authenticity determination is performed.

  In addition, the printed matter having a latent image of the present invention can be easily produced by a design in which two images are overlapped in the same region by a special halftone dot configuration, and there is no design restriction. .

  Furthermore, the printed matter having the appearance of the latent image by changing the observation angle using the conventional metallic gloss material is a simple solid printing configuration, whereas the printed matter having the latent image of the present invention is Since a special halftone dot configuration is used, the anti-duplication effect is high.

It is a figure which shows an example of the printed matter which has a latent image in this invention. It is a figure which shows an example of the visible image in this invention, a 1st latent image, and a 2nd latent image. It is a figure for demonstrating the relationship of the halftone dot diameter in the halftone dot structure of this invention. It is a graph which shows an example of the spectral reflectance of the ink containing the base material, metal powder ink, and infrared rays absorption pigment | dye concerning this invention. It is a figure for demonstrating the halftone dot structure in the 2nd Embodiment of this invention. 4 is a graph showing an example of spectral transmittance of white ink and magenta ink according to the present invention. It is a figure for demonstrating the observation state when observing the printed matter of this invention. It is a graph which shows the color difference (DELTA) E of each 1st halftone dot and 2nd halftone dot in the diffused light area | region or specular reflection light area | region under the visible light source concerning this invention. It is a graph which shows color difference (DELTA) E of each 2nd halftone dot and 3rd halftone dot in the diffused light area | region or specular reflection light area | region under the visible light source concerning this invention. It is a figure for demonstrating a principle when a visible image can be visually recognized. It is a figure for demonstrating a principle when the 1st latent image can be visually recognized. It is a figure for demonstrating a principle when a 2nd latent image image can be visually recognized. It is a figure which shows an example of the printed matter which has a latent image in this invention. It is a figure which shows an example of the visible image in this invention, a 1st latent image, and a 2nd latent image. It is a figure for demonstrating the halftone dot structure in the 2nd Embodiment of this invention.

  Embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments to be described below, and includes various other embodiments within the scope of the technical idea described in the claims.

  FIG. 1 is a diagram showing an example of a printed material (1) (hereinafter referred to as “printed material”) having a latent image in the present invention. As shown in FIG. 1A, this printed matter (1) has a printing region (3) in which the latent image in the present invention is formed on at least a part of the substrate (2).

  The substrate (2) in the present invention is not particularly limited, and paper sheets such as high-quality paper, coated paper, and art paper, films, and the like can be used. However, by changing the observation angle from the diffuse light region to the regular reflection light region with respect to the illumination light source at a fixed position, which is a feature point of the present invention, the characteristics of the material whose brightness and / or color change are effectively exhibited. Therefore, the smoothness of the base material (2) is preferably 1,000 seconds or more and less than 2,000 seconds. The smoothness was measured by a test method defined in Japanese Industrial Standard JIS P 8119 and measured using a Digibeck smoothness tester (DB-2 type, manufactured by Toyo Seiki Seisakusho Co., Ltd.).

  In the print area (3), three images which are characteristic in the present invention are formed, and the halftone dot structure forming each image is shown in a partially enlarged view of FIG. It is.

  As shown in FIG. 1B, in the halftone dot configuration constituting the print region (3) of the present invention, three halftone dots having different sizes are arranged in the same region. The three halftone dots are the first halftone dot (4) arranged at the outermost side, the second halftone dot (5) arranged within the first halftone dot (4), and the second halftone dot. It is defined as a third halftone dot (6) arranged in the second halftone dot (5).

  FIG. 2 shows each image formed by arranging a plurality of these three halftone dots. FIG. 2A is a visible image (7) visible in a diffused light region under a visible light source formed by arranging a plurality of first halftone dots (4), and FIG. 2 is a first latent image (8) that is visible under an infrared light source formed by arranging a plurality of halftone dots (5). FIG. 2 (c) shows a third halftone dot (6). It is the 2nd latent image image (9) visually recognizable in the regular reflection light area under the visible light source formed in multiple numbers. The visual recognition principle of these three images will be described later.

  As described above, the printed matter (1) in the present invention includes three images that appear by changing the observation conditions, and each image is formed by three halftone dots. Therefore, each halftone dot will be described below.

(First embodiment)
First, the first halftone dot (4) will be described. The first halftone dot (4) is a halftone dot that forms a visible image (7) that is visible in the diffused light region under the visible light source. A continuous tone visible image (7) can be formed by the size of the halftone dot of the first halftone dot (4).

  The first halftone dot (4) is formed using a material that does not contain an infrared absorbing dye. When the first halftone dot (4) is formed of a material that does not contain an infrared absorbing pigment, the visible image (7) can be visually recognized when observed using a special appraisal device such as an infrared camera. become unable. The material that does not contain an infrared absorbing dye is not particularly limited as long as it does not have infrared absorbing properties. Among basic four-color inks, cyan (C), magenta (M), and yellow (Y) It has the property of not absorbing, and if the black color is expressed by superimposing these three colors, the same effect as a dye that does not absorb infrared rays can be obtained. Alternatively, chromofine black ink (manufactured by Dainichi Seika Kogyo Co., Ltd.) or dye-based ink for inkjet printers (for example, dye-based black ink manufactured by Canon, etc.) can also be used. Furthermore, a continuous tone visible image (7) may be formed by forming a first halftone dot (4) with a single color special color ink that does not contain an infrared absorbing dye and arranging a plurality of the first halftone dots (4).

  Next, the second halftone dot (5) will be described. This second halftone dot (5) is a halftone dot that forms a first latent image (8) that is visible under an infrared light source. The first latent image (8) having a continuous tone can be formed by the size of the second halftone dot (5).

  The second halftone dot (5) is placed so as to overlap within the first halftone dot (4). The second halftone dot (5) is made smaller than a certain halftone dot diameter set in the first halftone dot (4). The constant halftone dot diameter is the minimum size among the plurality of first halftone dots (4) arranged, and the second halftone dot (5) is the first halftone dot (4). Form in a range not exceeding the minimum size.

  FIG. 3 is a diagram for explaining the limit of the size of the second halftone dot (5). In FIG. 3, only the first halftone dot (4) and the second halftone dot (5) are shown for explanation. FIG. 3A and FIG. 3B show a first halftone dot (4) and a second halftone dot (5) having different sizes.

  The first halftone dot (4) shown in FIG. 3B has the smallest halftone dot diameter at the first halftone dot (4), and the diameter is X. Therefore, the maximum size of the second halftone dot (5) is formed in a range not exceeding the diameter X which is the minimum size of the first halftone dot (4). In FIG. 3A, the minimum size (A) of the first halftone dot (4) is indicated by a dotted line.

  If the second halftone dot (5) is formed exceeding the minimum size (A) of the first halftone dot (4), the second halftone dot (5) is formed with respect to the visible image (7). This is because the first latent image (8) is affected, and a clear visible image (7) cannot be formed.

  The second halftone dot (5) is formed of a material containing an infrared absorbing dye. Examples of the material containing the infrared absorbing dye include black (Bk) ink mainly composed of carbon black, and the material forming the second halftone dot (5) in the present invention is at least one in the infrared region. Any material having a wavelength peak (particularly ink) may be used, and the present invention is not limited to this.

  By forming the second halftone dot (5) with a material containing an infrared absorbing dye, the first latent image (8) cannot be visually recognized under a visible light source, but when observed under an infrared light source. The first latent image (8) can be visually recognized.

  Next, the third halftone dot (6) will be described. This third halftone dot (6) is a halftone dot that forms a second latent image (9) that is visible in the specularly reflected light region under a visible light source. A continuous latent second latent image (9) can be formed by the size of the third halftone dot (6).

  The third halftone dot (6) is placed so as to overlap with the second halftone dot (5). Note that the third halftone dot (6) is smaller than a certain halftone dot diameter set in the second halftone dot (5). The constant halftone dot diameter is the minimum size among the plurality of second halftone dots (5) arranged, and the third halftone dot (6) is the second halftone dot (5). Form in a range not exceeding the minimum size.

  The size of the third halftone dot (6) is the same as the size limit of the second halftone dot (5) described above, and the details are omitted, but the visible image (7) In order not to affect the first latent image (8), it is formed in a range not exceeding the minimum size of the second halftone dot (5).

  Therefore, the relationship between the sizes of the first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) is the minimum diameter of the first halftone dot (4) ≧ second. The maximum diameter of the halftone dot (5), the minimum diameter of the second halftone dot (5) ≧ the maximum diameter of the third halftone dot (6).

When the viewing angle of the third halftone dot (6) is changed from the diffuse light region to the regular reflection light region with respect to the illumination light source at a fixed position, the color difference ΔE from the second halftone dot (5) has a predetermined value. It is formed using a material that changes. The color difference in the present invention is defined by ΔE in the CIE 1976 L ^* a ^* b ^* color system. The CIE 1976 L ^* a ^* b ^* color system is a color space recommended by the CIE (International Lighting Commission) in 1976, and is defined in JIS Z 8729 in the Japanese Industrial Standards. The color difference is the distance in a color space of two colors, and the color difference in the CIE 1976 L ^* a ^* b ^* color system is the difference in L ^* , difference in a ^* and difference in b ^* , respectively. It can be obtained by adding the square and taking the square root.

  The change in the color difference ΔE means that the brightness and / or color changes when the observation angle is changed with respect to the illumination light source at a fixed position. For example, by changing the observation angle with respect to an illumination light source at a fixed position, a printing ink is produced using a material that changes in brightness and / or color, and is provided as a printing region on a substrate such as paper to be printed. A is prepared. Similarly, printing ink is prepared using a material that does not change brightness and / or color by changing the observation angle with respect to the illumination light source at a fixed position. Printed matter B is prepared. Let X be the color difference ΔE between the printed material A and the printed material B. Next, the color difference ΔE between the printed matter A and the printed matter B is measured again after changing the observation angle under the illumination light source in which the printed matter A and the printed matter B are placed at fixed positions. If the measured color difference ΔE is a value different from X described above, the color difference ΔE has changed. As described above, if the brightness and / or color changes by changing the observation angle with respect to the illumination light source at a fixed position, the material becomes a material whose color difference ΔE changes depending on the observation angle. The diffused light region in the present invention is a region where the light receiving angle is −10 to 10 ° when the incident light angle from the illumination light source at a fixed position is 45 °. When the incident light angle from the illumination light source is 45 °, it indicates a region where the light receiving angle is 35 to 55 °. The principle that the color difference ΔE changes by a predetermined value will be described later.

  Examples of the material whose color changes depending on the observation angle and whose color difference ΔE from other regions changes by a predetermined value include a glittering material. Examples of the glittering material include metal powder ink, foil (metal foil), those formed on the substrate (1) by metal vapor deposition, metals, and metallic glossy films. Metal powder ink is ink which shows a metal color by one printing. Metal powder ink is prepared by mixing a fine metal powder in a vehicle. Metal powder ink includes gold ink and silver ink. Gold ink is an ink prepared by mixing a fine brass powder in a vehicle, and silver ink is an ink prepared by mixing a fine aluminum powder in a vehicle.

  Moreover, you may form foil (metal foil) on a paper base material instead of metal powder ink. Examples of the foil include gold leaf and silver leaf. The foil is applied onto the substrate by a hot stamp method or a cold foil method. The hot stamping method is a method in which a sheet-like foil is stacked on a substrate, pressed with a high-temperature metal stamp, and pressed onto the substrate. The cold foil method is a method in which an adhesive is applied to a base material, a sheet-like foil is stacked on the base material, and the foil is transferred by pressurization.

  Instead of foil (metal foil), aluminum (such as Takeo Co., Ltd., off metal N 165 kg, etc.) formed on the base material (1) by metal vapor deposition may be used. Moreover, it is good also considering base material (1) itself as metals, such as stainless steel and aluminum. Furthermore, you may use a metallic glossy film (Toray Industries, Inc., PICASUS etc.) for a base material (1). The metallic glossy film is a polyester film formed by laminating different kinds of polymers in multiple layers, and is a material that can obtain metallic gloss without using metal.

  The third halftone dot (6) is formed of a material in which the color difference ΔE between the first halftone dot (4) and the second halftone dot (5) changes by a predetermined value in the regular reflection light region under a visible light source. Therefore, since the second latent image (9) formed by arranging a plurality of third halftone dots (6) is visible, in the diffused light region under the visible light source, If the second latent image (9) can be visually recognized, the visible image (7) cannot be clearly observed.

  Therefore, in the diffused light region, it is necessary to form the first halftone dot (4) and the second halftone dot (5) and the third halftone dot (6) in the same color. By making the three halftone dots the same color in the diffused light region, the first latent image (8) and the second latent image (9) have an effect when the visible image (7) is viewed. Things will disappear.

The term “equal color” in the present invention indicates that the color difference ΔE ^* ab (hereinafter referred to as “ΔE”) is less than 6 when observed in a diffused light region under a visible light source. In general, when the color difference ΔE is around 6, there is a possibility that a different color is visually recognized. However, in the present invention, the first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) cannot be visually recognized by distinguishing each region with the naked eye. It is composed of various halftone dots. Therefore, as described above, when the color difference ΔE is less than 6, the first latent image (8) and the second latent image (9) are visually recognized with the naked eye in the diffused light region under the visible light source. The first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) are visually recognized as the same color.

  Note that due to metamerism, when viewed in a diffused light region under a visible light source, a color visually recognized by the naked eye is viewed in a different color when observed in a diffused light region under a specific light source. Even in this case, in the present invention, the first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) are formed in the same color.

  FIG. 4 is a diagram showing an example of the spectral reflectance of an ink containing a base material (2), a metal powder ink and an infrared absorbing dye according to the present invention. (A) in the graph of FIG. 4 is the spectral reflectance of the substrate (2) in the present invention, and photographic paper for an inkjet printer (Photo paper <Gloss> made by EPSON) was used as a measurement sample. (B) is the spectral reflectance of the third halftone dot (6) in the present invention, and solid printing is performed by inkjet printing using a metal powder ink (manufactured by Nippon Paint Co., Ltd., gold colloid ink) as a measurement sample. The thing which gave is used. (C) is a spectral reflectance of a material containing an infrared absorbing dye for forming the second halftone dot (5) in the present invention, and is solid-printed by inkjet printing using carbon black (matt black made by EPSON). The thing which gave is used. The spectral reflectance was measured using a self-recording spectrophotometer (manufactured by HITACHI, model U-4000).

  Comparing changes in spectral reflectance in a visible light region of 400 to 760 nm and an infrared region of 760 to 800 nm, the spectral reflectance in the photographic paper (a) is almost constant at around 90% in any region. is there. The spectral reflectance in the metal powder ink (b) is low in both the visible light region and the infrared region, and in the infrared region, the metal powder ink (b) has a low value of around 40%. The infrared absorbing material (c) was almost constant at around 10% in any region. At the same wavelength, the higher the spectral reflectance, the lower the density is visually recognized (whiter), and the lower the spectral reflectance, the higher the density is visually recognized (blackish). When observed with an infrared camera, the photographic paper (a) was observed as white, the metal powder ink (b) as gray, and the material (c) containing the infrared absorbing dye as black.

  Therefore, since the first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) are the same color in the diffused light region under the visible light source, the first latent image ( 8) and the second latent image (9) are not visible. In the specularly reflected light region under a visible light source, the first halftone dot (4) and the second halftone dot (5) are of the same color, so that a uniform flat halftone state is obtained. The image (8) cannot be visually recognized.

  Further, when the observation is performed in the infrared region using a special device such as an infrared camera, the second halftone dot (5) is black and the third halftone dot (6) is visually recognized as gray as described above. . Therefore, since the third halftone dot (6) visually recognized in gray arranged in the second halftone dot (5) visually recognized in black is actually difficult to confirm, in the infrared region, The second latent image (9) formed by the third halftone dot (6) cannot be confirmed, and only the first latent image (8) can be confirmed.

  The second halftone dot (5) arranged in the first halftone dot (4) and the third halftone dot (6) arranged in the second halftone dot (5) are respectively superimposed or It is possible to form by hair removal. However, when formed by tweezers, high printing accuracy is required, so that they are preferably formed in an overlapping manner.

  If the printing accuracy is lowered, the first latent image (8) and the second latent image (9) may be affected in the visible image (7), or the first latent image may be affected. In the image (8), the second latent image (9) is affected, and there is a possibility that each clear image cannot be formed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described, but a part of the same configuration as the first embodiment is omitted.

  In the second embodiment, the base material (2 ′) itself is formed of a material whose color changes by changing the observation angle from the diffuse light region to the regular reflection light region with respect to the illumination light source at a fixed position. On the base material (2 ′), the base material (2 ′) is concealed so as not to change the color by changing the observation angle with respect to the illumination light source at a fixed position from the diffuse light region to the regular reflection light region. The third halftone dot (6 ′) is formed by excluding a part of the material and printing is not performed on the third halftone dot (6 ′) region formed in the first embodiment. And the area excluding the concealing material for concealing the base material (2 ′) to be the same place, the base material (2 ′) itself is partially exposed to form a third dot ( 6 ′). The printed matter obtained thereby is obtained by changing the observation angle with respect to the illumination light source at a fixed position from the diffused light region to the regular reflection region, through the region (11) to which a concealing material described later is not applied, The color difference ΔE between the third halftone dot (6 ′) formed by partially exposing the glittering material 2 ′) and the second halftone dot (5 ′) changes by a predetermined value. The second latent image (9) becomes visible. That is, the material whose color changes by changing the observation angle with respect to the illumination light source at a fixed position on the base material (2 ′) itself from the diffuse light region to the regular reflection light region is the first This is a material in which the color difference ΔE between the third halftone dot (6 ′) and the second halftone dot (5 ′) changes by a predetermined value. The details will be described below with reference to the drawings.

  FIG. 5 is an enlarged view of one halftone dot formed in the print area (3) in the second embodiment. As shown in FIG. 5A, the halftone dot configuration in the second embodiment is also the same as the first halftone dot configuration when the one formed on the print area (3) is confirmed from above. The second halftone dot (5 ′) is arranged in the first halftone dot (4 ′), and the third halftone dot (6 ′) is further located in the second halftone dot (5 ′). Is arranged.

  However, the details of the halftone dot configuration in the second embodiment are composed of three layers as shown in FIGS. 5B and 5C.

  First, the base material (2 ′) which is the lowermost layer is a feature point of the second embodiment, and the color is obtained by changing the observation angle from the diffuse light region to the regular reflection light region with respect to the illumination light source at a fixed position. Is formed of a material that changes. In this case, the base material (2 ') itself may use a material whose color changes, or a metal powder ink or foil (metal foil) is printed on a predetermined material (for example, fine paper). (3) Or you may give to the whole surface of a predetermined material. In any case, in the second embodiment, the base material (2 ') is formed of a material that changes color.

  On this base material (2 ′), an infrared absorbing dye is not contained, and the base material (2 ′) is changed from the diffuse light region to the regular reflection light region with respect to the visible light source at a fixed position. Thus, the concealment region (10) is formed using a material (hereinafter referred to as “concealment material”) for preventing the color from changing. The concealment region (10) has a region (11) where a concealment material is not applied in order to expose the base material (2 '). By doing so, the third halftone dot (6 ′) can confirm the glitter of the base material (2 ′) through the region (11) to which the concealing material is not applied. This halftone dot (6 ′) is formed of a glittering material.

  As the concealing material, white ink, mat ink (mat-type OP varnish) or the like can be used, but it does not contain an infrared absorbing dye, and the base material (2 ′) is used with respect to a fixed position illumination light source. Thus, the material is not limited to this as long as the material does not change the color by changing the observation angle from the diffuse light region to the regular reflection light region. The white ink includes Dicure RTX white manufactured by DIC Corporation as UV ink for offset printing, and LIOJET FV03 white manufactured by Toyo Ink Manufacturing Co., Ltd. as UV ink for inkjet printing. Since the white ink has the least influence on the visible image (7) formed by the first halftone dot (4 ') formed on the white ink, in the first embodiment, the present invention is applied to the paper substrate. The same visual effect as when the halftone dot structure is formed can be achieved.

  The masking material is printed on the glittering substrate (2 ′) by the second latent image formed by the second embodiment of the present invention (other than the third halftone dot (6 ′)). This is because it plays a role of concealing the glitter so as not to affect the visibility of 9).

  The reason for using the concealing material that does not contain the infrared absorbing dye is that it does not affect the visibility of the first latent image (8) formed by the halftone dot structure of the present invention. When a concealing material containing an infrared absorbing dye is used, when the printed matter obtained by the halftone dot composition of the present invention is observed under an infrared light source, the first halftone dot (4 ′), the second halftone dot ( 5 ') and the third halftone dot (6') are all observed in high density (darker). Therefore, the second halftone dot (5 ′) cannot be distinguished from other halftone dots, and as a result, the first latent image (8) that can be observed under the infrared light source can be visually recognized. become unable.

  Further, the concealment region (10) formed of the concealment material preferably has a transmittance in the infrared region of 80% or less. When the transmittance in the infrared region of the concealment region (10) is 80% or more, when the printed matter obtained by the halftone dot configuration of the present invention is observed under an infrared light source, the substrate (2 ′) is The concealment region (10) to be concealed is transmitted, and all of the first halftone dots (4 ′) are transmitted and the base material (2 ′) is observed, so that the concentration is observed high (blackish). Therefore, the second halftone dot (4 ′) cannot be distinguished from other regions, and as a result, the first latent image (8) that can be observed under the infrared light source can be visually recognized. It is not preferable because it disappears.

  FIG. 6 is a graph showing an example of the spectral transmittance of white ink and magenta ink according to the present invention. FIG. 6A shows the spectral transmittance of the concealing material in the present invention, and white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.) was used as a measurement sample, and solid printing was performed on a PET film by inkjet printing. A thing was used. FIG. 3 (b) shows the spectral transmittance of the concealment material in the present invention. Using white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample, the PET film is formed by inkjet printing. A sample printed at a lower printing density was used.

  FIG. 6 (c) shows the spectral transmittance of the material that does not contain the infrared absorbing dye in the present invention. Using magenta ink (LIOJET FV03 Magenta manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample, it was applied to a PET film by inkjet printing. A solid-printed one was used. Note that the spectral transmittance shown in FIG. 6 is obtained by dividing the spectral transmittance of each measurement sample by the spectral transmittance of a single PET film as a base material. (Measured using HITACHI U-4000 model).

  Comparing changes in spectral transmittance in the infrared region of 760 to 800 nm, the spectral transmittance in the concealing material (a) is almost constant at about 50% in any region. The spectral transmittance of the concealing material (b) printed at a reduced printing density is about 80% in the infrared region, which is a higher value than the concealing material (a) printed solid. The infrared transmitting material (c) containing no infrared absorbing pigment has a high value in the infrared region, about 95%, compared with the white ink (a) printed solid and the white ink (b) printed at a reduced printing density. It has become. In the case of a material that does not contain an infrared absorbing dye at the same wavelength, a lower spectral transmittance is visually recognized as a higher concentration (whiter), and conversely, a higher spectral transmittance has a lower concentration (transparent). It is visible. When observed with an infrared camera, the concealing material (a) is white, the concealing material (b) printed at a lower printing density is pale white, and the infrared transmitting material (c) is almost transparent. It was done.

  The substrate (2 ') itself may be formed of a glittering material, but metal powder ink or foil (metal foil) may be formed on the entire surface of the substrate (2') such as paper.

  A first halftone dot (4 ′) is formed on the aforementioned concealment region (10), and a second halftone dot (5 ′) is formed in the first halftone dot (4 ′). . The point that the second halftone dot (5 ′) is formed in the first halftone dot (4 ′) is the same as that of the first embodiment, but in the second embodiment, FIG. ) And FIG. 5C, the third halftone dot (6) in the first embodiment is not formed in the second halftone dot (5 ′), and the blank area (12) and It has become.

  The blank region (12) and the region (11) to which the concealment material is not applied in the concealment region (10) are arranged at the same position, so that the base material (2 ′) is exposed (confirmation) at the position. Will be. Therefore, as a result, the halftone dot in the second embodiment is formed so that the third halftone dot (6 ′) is within the second halftone dot (5 ′) as shown in FIG. It will be formed. However, the third halftone dot (6 ') is substantially formed by the base material (2'). The printed matter thus obtained is obtained by changing the observation angle with respect to the illumination light source at a fixed position from the diffused light region to the regular reflection region, through the region (11) where no concealing material is applied, The color difference ΔE between the third halftone dot (6 ′) and the second halftone dot (5 ′) formed by partially exposing the glittering material is a predetermined value change. The second latent image (9) becomes visible. In the following description, even if the third halftone dot (6 ′) is formed so that the substrate is substantially exposed, the third halftone dot (6 ′) is under the visible light source at a fixed position. On the other hand, it is assumed that the color difference ΔE from the second halftone dot (5 ′) is changed by a predetermined value by changing the observation angle from the diffuse light region to the regular reflection light region.

(Observation principle of each image)
Each halftone dot for forming each image has been described. Here, the visible image (7), the first latent image (8), and the second latent image of the present invention in each halftone dot configuration described above. The visual recognition principle of the image image (9) will be described.

  First, the observation position necessary for visually recognizing the visible image (7) and the second latent image (9) will be described. As described above, the first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′), and the third halftone dot (6, 6 ′) are in the diffused light region under the visible light source. By visually recognizing with the same color, the visible image (7) can be visually recognized with the naked eye, and on the contrary, the first latent image (8) and the second latent image (9) cannot be visually recognized. Further, in the regular reflection light region under the visible light source, the second latent image (9) is configured to be visible with the naked eye. In general, the color of an object is determined by a light source, an observation environment (temperature), a spectral reflectance of the object, and the like. Although the way of visually recognizing colors varies depending on these observation conditions, the observation conditions in the present invention are constant conditions (for example, the observation condition: the light source is D65 and the observation environment is 20 ° C.).

  FIG. 7 shows the visible light source (R) and the viewpoint (1) when the printed matter (1) according to the present invention is observed with respect to the visible light source (R) at a fixed position in the diffused light region and the specularly reflected light region. It is the figure which showed three positional relationships of E1, E2) and printed matter (1). When the visible light source (R), the viewpoint (E1), and the printed material (1) are in the positional relationship shown in FIG. 7A, the observation is made in the diffused light region. Further, when the visible light source (R), the viewpoint (E2), and the printed material (1) are in the positional relationship shown in FIG. 7B, the observation is made in the regular reflection light region.

  Next, the principle that the color difference ΔE between the second halftone dot (5, 5 ') and the third halftone dot (6, 6') changes by a predetermined value due to the change in the observation angle will be described. As described above, the diffused light region in the present invention is a region where the light receiving angle is −10 to 10 ° when the incident light angle from the illumination light source at a fixed position is 45 °, and the specularly reflected light region is When the incident light angle from the illumination light source at a fixed position is 45 °, it is a region where the light receiving angle is 35 to 55 °. In the printed material (1), the first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) are shown in FIG. The positional relationship that means the diffused light region is the same color, and each region cannot be distinguished with the naked eye, and only the visible image (7) is visible.

  On the other hand, in the regular reflection light region shown in FIG. 7B, the third halftone dots (6, 6 ′) are formed using a material whose color difference ΔE changes by a predetermined value by changing the observation angle. Therefore, by changing the observation angle with respect to the illumination light source from the diffused light region to the specularly reflected light region, the brightness and / or color changes, and the second halftone dot (5, 5 ') and the third The color difference ΔE of the halftone dots (6, 6 ′) changes by a predetermined value. Therefore, the second latent image (9) formed by the third halftone dots (6, 6 ') is visible.

  FIG. 8A is a graph showing the color difference ΔE between the second halftone dots (5, 5 ′) and the third halftone dots (6, 6 ′) in the diffused light region under the visible light source. b) is a graph showing the color difference ΔE between the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) in the specularly reflected light region under the visible light source. The halftone dot configuration in FIG. 8 is the same as the configuration shown in FIG.

  In the measurement sample, the first halftone dot (4) is made into a circle having a line number of 80 and a diameter of 70 μm, and the second halftone dot (5) and the third halftone dot are formed on a base material (EPSON photographic paper <glossy>). Sample A (4 × 4 cm) prepared by printing the first halftone dot (4) by inkjet printing using process ink (manufactured by EPSON, cyan, magenta, yellow) without printing the halftone dot (6) of The second halftone dot (5) has the same number of lines and the same diameter as the first halftone dot (4), and the first halftone dot (4) is formed on the base material (EPSON photo paper <glossy>). And the second halftone dot (5) by inkjet printing using black ink (EPSON mat black) and process ink (EPSON, cyan, magenta, yellow) without printing the third halftone dot (6). Measurement sample B (4 x 4 cm) produced by printing It was measured by using each.

A graph showing the color difference ΔE between the first halftone dot (4) and the second halftone dot (5) in the diffused light region shown in FIG. 8A, and the specularly reflected light region shown in FIG. The color difference ΔE between the first halftone dot (4) and the second halftone dot (5) is a variable angle spectrophotometer type GSP-2 (manufactured by Murakami Color Research Laboratory Co., Ltd., hereinafter referred to as “measuring device”). ), The L ^* value, the a ^* value, and the b ^* value of the measurement sample A and the measurement sample B described above were measured, and the color difference ΔE was calculated from the obtained values.

  However, in order to reproduce the positional relationship meaning the diffused light region shown in FIG. 7A on the measuring apparatus, the incident light of the visible light source with respect to each measurement sample is fixed at 45 °, and the light receiving angle is −10 °. From 10 to 10 °. Further, in order to reproduce the positional relationship meaning the specularly reflected light region shown in FIG. 7B on the measuring apparatus, the incident light of the visible light source with respect to each measurement sample is fixed at 45 °, and the light receiving angle is set to 35 °. From 55 to 55 °. The calibration of the measuring apparatus was performed using a standard white plate 4020A with an incident light angle of 45 ° and a light receiving angle of 0 °, that is, a standard white plate with a completely diffusing surface.

  As shown in FIG. 8A, in the diffused light region, the color difference ΔE between the first halftone dot (4) and the second halftone dot (5) is 1.46 to 1.49. The first halftone dot (4) and the second halftone dot (5) are difficult to identify with the naked eye. As a result, the first latent image (8) formed in the visible image (7) cannot be visually recognized. Also in the regular reflection light region shown in FIG. 8B, the color difference ΔE between the first halftone dot (4) and the second halftone dot (5) is 1.24 to 5.16. The first halftone dot (4) and the second halftone dot (5) are difficult to identify with the naked eye. That is, under the visible light source, it is difficult to identify the first halftone dot (4) and the second halftone dot (5) with the naked eye, and the first latent image formed in the visible image (7). The image image (8) cannot be visually recognized.

  FIG. 9 is a graph showing the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) in the diffused light region or the specularly reflected light region under the visible light source according to the present invention, FIG. 9A shows the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) in the diffused light region, and FIG. 9B shows the second halftone dot in the specularly reflected light region. The color difference ΔE between the point (5) and the third halftone dot (6) is shown.

  In the measurement sample, the second halftone dot (5) is made into a circle having a diameter of 80 lines and a diameter of 35 μm, and the first halftone dot (4) and the third halftone dot are formed on the base material (EPSON photographic paper <glossy>). The second halftone dot (5) is printed by inkjet printing using black ink (EPSON mat black) and process ink (EPSON, cyan, magenta, yellow) without printing the halftone dot (6). The measured sample C (4 × 4 cm) and the third halftone dot (6) have the same number of lines and the same diameter as the second halftone dot (5), and are on the base material (EPSON photographic paper <glossy>). Ink jet printing of the third halftone dot (6) without using the first halftone dot (4) and the second halftone dot (5) by using metal powder ink (gold colloid ink manufactured by Nippon Paint Co., Ltd.) A measurement sample D (4 × 4 cm) printed and produced by It was measured by using Re respectively.

  A graph showing the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) in the diffused light region shown in FIG. 9A, and the specularly reflected light region shown in FIG. 9B. The color difference ΔE between the second halftone dot (5) and the third halftone dot (6) was measured using a measuring device. However, in order to reproduce the positional relationship meaning the diffused light region shown in FIG. 7A on the measuring apparatus, the incident light of the visible light source with respect to each measurement sample is fixed at 45 °, and the light receiving angle is −10 °. From 10 to 10 °. Further, in order to reproduce the positional relationship meaning the specularly reflected light region shown in FIG. 7B on the measuring apparatus, the incident light of the visible light source with respect to each measurement sample is fixed at 45 °, and the light receiving angle is set to 35 °. From 55 to 55 °. The calibration of the measuring apparatus was performed using a standard white plate 4020A with an incident light angle of 45 ° and a light receiving angle of 0 °, that is, a standard white plate with a completely diffusing surface.

  As shown in FIG. 9A, in the diffused light region, the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) is relatively between 1.43 and 1.47. Small value is shown. As described above, the second halftone dot (5) and the third halftone dot (6) can always be said to be the same color in the diffused light region because the color difference ΔE is equal if it is less than 6. Therefore, it is difficult to identify the second halftone dot (5) and the third halftone dot (6) with the naked eye. As a result, the second latent image ((2) formed in the visible image (7)). 9) cannot be visually recognized.

  On the other hand, in the regular reflection light region shown in FIG. 9B, there is a light receiving angle where the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) is 7.38. . In the diffused light region (for example, the light receiving angle 0 °), the color difference ΔE between the second halftone dot (5) and the third halftone dot (6) is 1.45, and the specularly reflected light region (for example, the light receiving angle) The color difference ΔE between the second halftone dot (5) and the third halftone dot (6) at 45 ° is 7.38. That is, the color difference ΔE changes from 1.45 to 7.38 by 5.93 by changing the observation angle from the diffuse light region to the regular reflection light region. Therefore, when the color difference ΔE is changed by 5 or more, the second halftone dot (5) and the third halftone dot (6) can be identified with the naked eye, and as a result, formed in the visible image (7). The second latent image (9) thus made can be visually recognized.

  Note that, under the same observation condition, the diffused light region and the regular reflection light region can be switched by tilting the printed matter (1). That is, by tilting the printed material (1), the third halftone dots (6, 6 ') can be identified with the naked eye. As a result, the second latent image (9) formed in the visible image (7) can be viewed.

(Visibility principle of visible image in the present invention)
The principle that a visible image can be visually recognized will be described in more detail. FIG. 10 is a plan view and a schematic view when the printed region (3) of the printed matter (1) according to the present invention is visually recognized in the diffused light region under the visible light source (R) at a fixed position. The printed area (3) shown in FIG. 10 (a) has a first halftone dot (4, 4) in the diffused light area under the visible light source (R) as shown in the partially enlarged view of FIG. 10 (b). 4 ′) is visible with the naked eye. That is, the visible image (7) can be visually recognized. The first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) are visually recognized in the same color in the diffused light region under the visible light source. This makes it impossible to distinguish with the naked eye. That is, the first latent image (8) formed by the second halftone dots (5, 5 ′) and the second latent image (9) formed by the third halftone dots (6, 6 ′) are: It cannot be seen with the naked eye. Therefore, when the printed region (3) of the printed matter (1) is confirmed with the naked eye in the diffused light region under the visible light source (R), only the visible image (7) is visible.

  FIG. 10C is a schematic diagram when the printed region (3) of the printed matter (1) according to the present invention is visually recognized in the diffused light region under the visible light source (R) at a fixed position. The principle that only the visible image (7) is visible with the naked eye in the diffused light region under the visible light source (R) will be described with reference to FIG. When the printed region (3) of the printed matter (1) is visually recognized in the diffused light region under the visible light source (R) with the naked eye, first, the visible light source is displayed at the first halftone dot (4, 4 ′). Incident light (r) from (R) generates specularly reflected light and diffused light, and diffused light is obtained in the diffused light region.

  At the second halftone dot (5, 5 '), incident light (r) from the visible light source (R) generates specularly reflected light and diffused light, and diffused light is obtained in the diffused light region. At the third halftone dot (6, 6 '), the incident light (r) from the visible light source (R) generates specularly reflected light and diffused light, and diffused light is obtained in the diffused light region. The first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) are the same color when observed in the diffuse light region under the visible light source. Therefore, the difference in diffused light at each halftone dot cannot be confirmed with the naked eye.

  In the halftone dot configuration of the present invention, the second halftone dot (5, 5 ′) is arranged so as to overlap the first halftone dot (4, 4 ′), and further, the second halftone dot (5, The third halftone dot (6, 6 ′) is superimposed on 5 ′). Maximum diameter and minimum diameter at the first halftone dot (4, 4 ′), maximum diameter and minimum diameter at the second halftone dot (5, 5 ′), maximum diameter at the third halftone dot (6, 6 ′) The minimum diameter of the first halftone dot (4, 4 ′) ≧ the maximum diameter of the second halftone dot (5,5 ′) and the second halftone dot (5,5 ′). The minimum diameter ≧ the maximum diameter of the third halftone dot (6, 6 ′).

  In the diffused light region under the visible light source, the intensity of the diffused light of the visible image (7), the first latent image (8), and the second latent image (9) is substantially constant. Therefore, the second halftone dot (5, 5 ′) is arranged so as to overlap within the first halftone dot (4, 4 ′), and the third halftone dot (5, 5 ′) is placed inside the second halftone dot (5, 5 ′). The points (6, 6 ′) are arranged in an overlapping manner, and the first halftone dot (4, 4 ′) is replaced with the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′). Are visually recognized in the same color, the first latent image (8) and the second latent image (9) are not visually recognized, and only the visible image (7) can be visually recognized.

(First viewing principle of latent image in the present invention)
FIG. 11 is a plan view and a schematic view when the print region (3) of the printed matter (1) formed by the halftone dot structure related to the present invention is observed through the infrared display device under the infrared light source (K). is there. The principle that the first latent image (8) can be observed under the infrared light source (K) will be described with reference to FIG. When the print area (3) of the printed matter (1) is observed with the infrared display device under the infrared light source (K) as shown in the partially enlarged view of FIG. 11B, the first halftone dot (4, 4 ') is brightly observed because it is made of a material that does not contain an infrared absorbing dye. In addition, although indicated by a dotted line in the drawing, the dotted line is not visually recognized in practice.

  As shown in FIGS. 4A and 4B, the third halftone dot (6, 6 ′) is a photographic paper (a) whose spectral reflectance is the base material (2) in the infrared region. Compared to the above, the concentration is higher (darker) than the base material (2). The second halftone dot (5, 5 ′) is made of a material containing an infrared absorbing dye, and is set to be the same color as the third halftone dot (6, 6 ′) in the diffused light region. Thus, when observed in the infrared absorption region, it is observed at the same concentration as in FIG. That is, the first latent image (8) can be observed in the infrared region.

(Principle of visual recognition of second latent image in the present invention)
FIG. 12 is a plan view when the printed region (3) of the printed matter (1) formed by the halftone dot structure according to the present invention is visually recognized in the specularly reflected light region under the visible light source (R) at a fixed position. FIG. The printed matter (1) shown in FIG. 12 (a) has a third halftone dot (6, 6) in the specularly reflected light region under the visible light source (R) as shown in the partially enlarged view of FIG. 12 (b). 6 ′) can be distinguished from the first halftone dot (4, 4 ′) and the second halftone dot (5, 5 ′) by the naked eye because the color difference ΔE changes and is visually recognized. Become. That is, the second latent image (9) can be viewed with the naked eye.

  FIG. 12C is a schematic diagram when viewed in the regular reflection light region under the visible light source (R). The principle that the second latent image (9) is visible with the naked eye in the specularly reflected light region under the visible light source (R) will be described with reference to FIG. When the printed region (3) of the printed matter (1) is visually recognized by the naked eye in the specularly reflected light region under the visible light source (R), first, the first halftone dot (4, 4 ′) is visible. Incident light (r) from the light source (R) generates specularly reflected light and diffused light to obtain specularly reflected light.

  At the third halftone dot (6, 6 ′) that forms the second latent image (9), the incident light (r) from the visible light source (R) generates specularly reflected light and diffused light, resulting in specular reflection. Light is obtained. At the second halftone dot (5, 5 '), specular reflected light and diffused light are generated by the incident light (r) from the visible light source (R), and specular reflected light is obtained. Therefore, the third halftone dot (6, 6 ′) is formed of ink using a material whose brightness and / or color changes by changing the observation angle, and the third halftone dot (6, 6). The regular reflection light of ') becomes higher than the regular reflection light of the first halftone dot (4, 4') and the second halftone dot (5, 5 '). With respect to the halftone dot (4, 4 ′) and the second halftone dot (5, 5 ′), a color difference Δ occurs in the third halftone dot (6, 6 ′), and the second latent image is obtained as a latent image. The image (9) can be visually recognized. Therefore, in the specularly reflected light region under the visible light source, when the printed matter (1) is observed, the second latent image (9) can be visually recognized.

  Note that, in the specularly reflected light region under the visible light source, the first halftone dot (due to the intensity of incident light from the visible light source (R), the glossiness of the base material (2), or the glossiness of each region ( 4, 4 ′) and the second halftone dot (5, 5 ′) differ in the specularly reflected light, and the first halftone dot (4, 4 ′) and the second halftone dot (5, 5 ′). ) Color difference ΔE may change.

  However, by changing the observation angle of the third halftone dot (6, 6 ′) with respect to the illumination light source at the fixed position from the diffused light region to the regular reflection light region, the first halftone dot (4, 4 ′) is obtained. ) And the second halftone dot (5, 5 ′) change amount of the color difference ΔE between the first halftone dot (4, 4 ′) and the third halftone dot (6, 6 ′), The amount of change in the color difference ΔE between the halftone dots (5, 5 ′) and the third halftone dots (6, 6 ′) is smaller. Therefore, due to the so-called visual masking effect, the first halftone dot (4, 4 ′) and the second halftone dot (5, 5 ′) are visually recognized by the naked eye in the regular reflection light region under the visible light source. Therefore, it is impossible to distinguish them with the naked eye, and the second latent image (9) formed in the visible image (7) becomes visible.

  The visual masking effect is due to the characteristics of human visual recognition. When two large and small stimuli are given close in time and space, large stimuli are recognized, and small stimuli are not recognized or recognized. This is a masking phenomenon (only large stimuli are visible) that becomes difficult and results in small stimuli being invisible. The area ratio of the first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) can be set, or the third halftone dot ( 6, 6 ′), depending on the selection of the material forming the first halftone dot, the amount of change in the color difference ΔE between the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) Approximating the amount of change in the color difference ΔE between (4, 4 ′) and the second halftone dot (5, 5 ′), the visual masking effect is weakened, and the visibility of the second latent image (9) is reduced There is. Therefore, the amount of change in the color difference ΔE between the second halftone dot (5, 5 ′) and the third halftone dot (6, 6 ′) becomes the first halftone dot (4, 4 ′) and the second halftone dot. The first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′), and the third halftone dot (6) so as to be larger than the change amount of the color difference ΔE of (5, 5 ′). , 6 ′) and a material for forming the third halftone dot (6, 6 ′) is preferably selected as appropriate.

  As described above, in the configuration of the present invention, the method of forming the visible image (7), the first latent image (8), and the second latent image (9) using three halftone dots has been described. However, the first halftone dot (4, 4 ′) is not arranged in the three halftone dots of the present invention, but the second halftone dot (5, 5 ′) and the third halftone dot (6, 6). When composed only of '), the visible image (7) is formed by the second halftone dots formed of the material containing the infrared absorbing dye. However, since the second halftone dot (5, 5 ′) is formed of the material containing the infrared absorbing dye as described above, it is formed by the second halftone dot (5, 5 ′). The image is also the first latent image (8) that can be observed under an infrared light source, and the visible image (7) and the first latent image (8) are confirmed as the same image even if the observation conditions are different. can do.

  When the printed matter formed with only the second halftone dots (5, 5 ′) and the third halftone dots (6, 6 ′) is observed in the regular reflection light region, the third halftone dots (6, 6 ′) are obtained. It goes without saying that the second latent image can be confirmed because it is formed of a material whose brightness and / or color changes by changing the observation angle with respect to the illumination light source at a fixed position.

  As for the halftone dot of the present invention, the second halftone dot (5, 5 ′) is formed of a material containing an infrared absorbing dye, and the third halftone dot (5, 5 ′) is formed inside the second halftone dot (5, 5 ′). By changing the observation angle of the halftone dot (6, 6 ′) with respect to the illumination light source at a fixed position from the diffuse light region to the regular reflection light region, the color difference ΔE from the second halftone dot changes by a predetermined value. Although the second halftone dot (5, 5 ′) has been described as being formed of a material, by changing the observation angle with respect to the illumination light source at a fixed position from the diffuse light region to the regular reflection light region, The third halftone dot (6, 6 ′) may be formed of a material containing an infrared absorbing dye, and the third halftone dot (6, 6 ′) may be formed of a material whose color difference ΔE from the third halftone dot changes by a predetermined value.

  However, in this case, an image that can be confirmed under an infrared light source can be slightly confirmed in an image that can be confirmed when the base material (2) is tilted and observed in the specular reflection light region. It becomes.

  In the visible image (7), the first latent image (8), and the second latent image (9) formed by the present invention, it is possible to appropriately set characters, numbers, symbols, designs, landscapes, and the like. However, in the second latent image (9), it is preferable to form a positive image in the case of letters, numbers, symbols, patterns, etc., and to form a negative image in the case of a person or landscape. It is preferable. In the above description, the first halftone dot (4, 4 ′), the second halftone dot (5, 5 ′), and the third halftone dot (6, 6 ′) are circular dots as halftone dots. However, it is not limited to a circle, but has a degree of freedom as disclosed in Japanese Patent No. 3478474 filed by the applicant of the present invention, such as a triangle, square, or polygon, a random shape, or the like. A halftone dot shape may be used.

  As a material for forming this halftone dot structure, known gravure ink, screen ink, process ink, ink for inkjet printer, foil (metal foil), and the like can be used. Moreover, as a method of forming each halftone dot on the substrate (2), an offset printing method, a gravure printing method, a screen printing method, a flexographic printing method, an ink jet printer, a laser printer, a metal vapor deposition, a hot stamp, a cold stamp, etc. There is no particular limitation.

  Hereinafter, the printed matter having a latent image in the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples, and may be within the technical scope described in the claims. Needless to say, it can be changed as appropriate.

  As Example 1, a gift certificate (1) having a printing region (3) according to the present invention formed in the lower left portion as shown in FIG. When this gift certificate (1) is observed in a diffused light region under a visible light source, the printed region (3) can confirm the Gothic character “NPB” shown in FIG. 2 (a), and the gift certificate (1). 2 is observed under an infrared light source, the “house” shown in FIG. 2B can be confirmed. Further, when the gift certificate (1) is observed in a specular reflection light region under a visible light source, FIG. The three letters “NPB” in the Mincho style shown can be confirmed.

As the base material (2) of the gift certificate (1) in Example 1, photographic paper for inkjet printers (Photo paper <Gloss> made by EPSON) was used. This base material (2) was printed by an inkjet printer (PX-G930 manufactured by EPSON). Note that at least the halftone dot configuration in the print region (3) is formed by superimposing the three halftone dots of the circular dots shown in FIG.

  Each halftone dot has the same number of lines of 65, and the halftone dot diameter is a maximum diameter of the first halftone dot (4) of 180 μm, a minimum diameter of 130 μm, and the second halftone dot (5) is the maximum. The diameter does not exceed the minimum diameter of the first halftone dot (4), the minimum diameter is 50 μm, the third halftone dot (6) has a maximum diameter that is the minimum diameter of the second halftone dot (5). The range was not exceeded, and the minimum diameter was 0 μm.

  In addition, the first halftone dot (4) is formed using a process ink (cyan, magenta, yellow made by EPSON) that does not contain an infrared absorbing dye, and the second halftone dot (5) contains an infrared absorbing dye. Black ink (EPSON mat black) and process ink (EPSON cyan, magenta, yellow) are used, and the third halftone dot (6) uses gold ink (Nihon Paint Co., Ltd. gold colloid ink). Formed. The first halftone dot (4), the second halftone dot (5), and the third halftone dot (6) were formed so as to have the same color in the diffused light region under the visible light source.

  When the printed region (3) of the gift certificate (1) produced by the above configuration is observed with the naked eye in the diffused light region under the visible light source where the illumination light source is at a fixed position, the visible image shown in FIG. 7) Gothic characters “NPB” can be confirmed, and at that time, the pattern of “house” as the first latent image (8) and the Mincho body as the second latent image (9) The characters of “NPB” could not be confirmed.

  The gift certificate (1) is tilted from the state in which the visible image (7) can be confirmed, and the print area (3) is observed in the specular reflection light area. As a result, the second latent image (9) shown in FIG. ) Is the character of “NPB” in the Mincho style, and at that time, the character of “NPB” in the Gothic style that is the visible image (7) and “Home” that is the first latent image (8). The pattern could not be confirmed.

  Further, the printing area (3) of the gift certificate (1) is passed through an infrared display device (a CCD camera WAT-704R manufactured by Watec Co., Ltd. and a sharp cut filter IR-80 manufactured by Fuji Photo Film Co., Ltd.). As a result of the observation, the pattern of the “house” as the first latent image (8) can be confirmed. At that time, the characters “NPB” of the Gothic body as the visible image (7) and the second latent image ( 9) The letter “NPB” in the Mincho style cannot be confirmed.

  As Example 2, a gift certificate (1 ') having a printing region (3') according to the present invention formed in the lower right portion as shown in FIG. When this gift certificate (1 ′) is observed in a diffused light region under a visible light source, the print region (3 ′) can confirm a plurality of “stars” shown in FIG. 14A, and the gift certificate (1 ′). Is observed under an infrared light source, the print area (3 ′) can confirm the “smile pattern” shown in FIG. 14B, and the gift certificate (1 ′) can be reflected from the visible light source. When observed in the area, the print area (3 ′) can be confirmed by the characters “¥ 1000” shown in FIG.

  The base material (2 ′) of the gift certificate (1 ′) according to the second embodiment has the second halftone dot by changing the observation angle from the diffuse light region to the regular reflection light region with respect to the illumination light source at the fixed position. A material in which a color difference ΔE with a predetermined value is formed on a paper substrate by aluminum vapor deposition (manufactured by Takeo Co., Ltd., off metal N silver 165 kg) was used. This base material (2 ') was printed by an inkjet printing apparatus (Patterning JET manufactured by Tritech Co., Ltd.). Note that at least the halftone dot structure in the print region (3 ') is the three dot structure of the circular dots shown in FIG. 13B.

  FIG. 15 shows details of the configuration of the three halftone dots formed in the print area (3 ′) shown in FIG. FIG. 15A is an enlarged view of one of a plurality of halftone dots formed in the print area (3 ') as viewed from above. Each halftone dot has the same number of lines, and the halftone dot diameter is 180 μm for the first halftone dot (4 ′) and 130 μm for the minimum halftone dot (5 ′). The maximum diameter is in a range not exceeding the minimum diameter of the first halftone dot (4 ′), the minimum diameter is 50 μm, and the third halftone dot (6 ′) has a maximum diameter of the second halftone dot (5 ′). ), And the minimum diameter was 0 μm.

  For each halftone dot, the first halftone dot (4 ′) is formed using process ink (LIOJET FV03 cyan, magenta, yellow, manufactured by Toyo Ink Manufacturing Co., Ltd.) that does not contain an infrared absorbing dye. (5 ′) was formed using a black ink (LIOJET FV03 black manufactured by Toyo Ink Manufacturing Co., Ltd.) and a process ink (LIOJET FV03 cyan, magenta, yellow manufactured by Toyo Ink Manufacturing Co., Ltd.) containing an infrared absorbing dye.

  As for the third halftone dot (6 ′), as shown in FIG. 15B, the process ink described above is not printed, but is set as a blank area (12 ′), and the first halftone dot (4 ′) and the first halftone dot (4 ′) White ink (LIOJET FV03, manufactured by Toyo Ink Manufacturing Co., Ltd.), which is a concealing material that suppresses the gloss of aluminum on aluminum formed by metal vapor deposition on the base material (2 ') under the halftone dot (5'). Using white, solid printing was performed so as not to print only the area located at the same position as the blank area (12 ') serving as the third halftone dot (6'). Therefore, as shown in the cross-sectional view of FIG. 15 (c), illumination at a fixed position on the base material (2 ′) through the blank area (12 ′) and the area (11 ′) where no white ink is printed. By changing the observation angle with respect to the light source from the diffuse light region to the regular reflection region, the third halftone dot (6 ′) is formed of aluminum of the material (13) whose color changes. . The first halftone dot (4 '), the second halftone dot (5'), and the third halftone dot (6 ') were formed so as to have the same color in the diffused light region under the visible light source.

  When the printed region (3 ′) of the gift certificate (1 ′) produced by the above configuration is observed with the naked eye in the diffused light region under the visible light source where the illumination light source is at a fixed position, the visible region shown in FIG. A plurality of “star” patterns as the image (7 ′) can be confirmed. At that time, the “smile” pattern as the first latent image (8 ′) and the second latent image (9 ′) A character of “¥ 1000” could not be confirmed.

  The gift certificate (1 ′) is tilted from the state where the visible image (7 ′) is confirmed, and the print area (3 ′) is observed in the specular reflection light area. As a result, the second latent image shown in FIG. The character “¥ 1000” that is the image (9 ′) can be confirmed, and at that time, the plurality of “star” patterns that are the visible image (7 ′) and the “smile” that is the first latent image (8 ′). The pattern “” could not be confirmed.

  Furthermore, the printing area (3 ′) of the gift certificate (1 ′) is an infrared display device (a CCD camera WAT-704R manufactured by Watec Co., Ltd. and a sharp cut filter IR-80 manufactured by Fuji Photo Film Co., Ltd.). The “smile” pattern, which is the first latent image (8 ′), can be confirmed. At that time, a plurality of “star” patterns, which are the visible image (7 ′), and the second latent image (8 ′) can be confirmed. The character “¥ 1000” in the image (9 ′) could not be confirmed.

DESCRIPTION OF SYMBOLS 1 Printed matter 2 which has a latent image, 2 'base material 3 Print area 4, 4' 1st halftone dot 5, 5 '2nd halftone dot 6, 6' 3rd halftone dot 7 Visible image 8 1st Latent image 9 Second latent image 10 Hidden area 11 Area 12 where no hiding material is applied Blank area 13 Material whose color changes

Claims (8)

A print area is formed on at least a part of the substrate. In the print area, a visible image and two latent image images are formed by three types of halftone dots, and each image can be visually recognized by changing the observation conditions. Printed material,
A plurality of first halftone dots are formed using a material that does not contain an infrared absorbing dye to form the visible image,
The second halftone dot is superimposed on the first halftone dot by a material containing an infrared absorbing dye to form a first latent image,
The third halftone dot is made of a material whose color difference ΔE with the second halftone dot changes by a predetermined value by changing the observation angle with respect to the illumination light source at a fixed position from the diffuse light region to the regular reflection light region. A second latent image is formed by being superimposed on the second halftone dot;
By forming the first halftone dot, the second halftone dot, and the third halftone dot so as to be the same color in the diffused light region under the visible light source,
In the printed matter, the visible image is visually recognized in the diffused light region, the first latent image pattern is observed under an infrared light source, and the observation angle is changed from the diffused light region to the regular reflected light region with respect to the illumination light source at a fixed position. A printed matter having a latent image, wherein the second latent image pattern is visible by being changed. A print area is formed on at least a part of the substrate. In the print area, a visible image and two latent image images are formed by three types of halftone dots, and each image can be visually recognized by changing the observation conditions. Printed material,
The base material is formed of a material whose color changes by changing an observation angle from a diffuse light region to a regular reflection light region with respect to an illumination light source at a fixed position at least in a region corresponding to the print region,
Concealment that does not change color by not containing infrared-absorbing dye on the base material, and changing the observation angle of the base material from the diffused light region to the regular reflection light region with respect to the illumination light source at a fixed position. A concealment region is formed using the material,
The concealing region is composed of a region where a concealing material for concealing a base material is applied and a region where a concealing material for partially exposing the base material is not applied,
A first halftone dot and a second halftone dot are arranged on a region to which the concealing material is applied, and a plurality of the first halftone dots are arranged using a material not containing an infrared absorbing dye, whereby the visible image is displayed. Form the
A second halftone dot is formed of a material containing an infrared absorbing dye and has a partially blank area in the first halftone dot to form a first latent image,
The second halftone dot formed by exposing the base material by arranging the blank area of the second halftone dot and the area where the concealment material is not provided in the concealment area at the same position. Latent image is formed,
By forming the first halftone dot, the second halftone dot, and the third halftone dot so as to be the same color in the diffused light region under the visible light source,
In the printed matter, the visible image is visually recognized in the diffused light region, the first latent image pattern is observed under an infrared light source, and the observation angle is changed from the diffused light region to the regular reflected light region with respect to the illumination light source at a fixed position. By changing, the color difference ΔE between the second halftone dot and the third halftone dot changes by a predetermined value, and the second latent image pattern is visible. Printed matter. 3. The printed matter having a latent image according to claim 2, wherein the blank area of the second halftone dot and the area where the concealment material is not applied in the concealment area have the same shape and size. The second halftone dot is smaller than a constant halftone dot diameter set in the first halftone dot, and the third halftone dot is a constant halftone dot diameter set in the second halftone dot. The printed matter having a latent image according to any one of claims 1 to 3, wherein the printed matter is smaller than the printed matter. The material in which the color difference ΔE with the second halftone dot changes by a predetermined value is obtained by changing the observation angle from the diffused light region to the specularly reflected light region with respect to the illumination light source at a fixed position. 5. The material according to claim 1, wherein the color difference ΔE from the second halftone dot in the specular reflection light region changes by 5 or more with respect to the color difference ΔE from the second halftone dot. A printed matter having the latent image according to the item. The material in which the color difference ΔE from the second halftone dot changes by a predetermined value is a glittering material, and the glittering material is any one of metal powder ink, foil, metal, or metallic glossy film. The printed matter having a latent image according to claim 5. The printed matter having a latent image according to any one of claims 1 to 6, wherein the material containing the infrared absorbing dye is a colored ink containing a material having at least one wavelength peak in the infrared region. . The printed material having a latent image according to any one of claims 1 to 6, wherein the material that does not include the infrared absorbing pigment is colored ink of cyan, magenta, or yellow or single color special color ink.

Images