JP2012106435A - Printing medium with transparent latent image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed matter configured such that three images are visible under different observing conditions, which are under reflected light, under transparent light, and under infrared light source, by using a precise dot configuration.SOLUTION: In the printed matter, at least a part of the surface of a transparent base material has a transparent latent image area in which an image is formed using three dots. The first dots form a visible image of continuous gradation by their being arranged by use of a material that contains no infrared absorbing dye. The third dots form a first latent image by their being arranged within the first dots by use of a material that contains the infrared absorbing dye. The second dots are arranged within the second dots by use of a transparent material, thereby forming the second latent image. The printed matter is formed so that the first, the second, and the third dots have an identical color under reflected light.

Description

  The present invention is intended for banknotes, passports, securities, product tags, various certificates, and particularly cards such as ID cards, for images under reflected light, images under transmitted light, and images under an infrared light source. The present invention relates to a print medium that is difficult to forge and duplicate by forming three different images.

  In recent years, counterfeit products of valuable printing media such as banknotes, passports and securities have become a serious problem due to the high functionality and high image quality of copiers. For this reason, various techniques have been developed for valuable print media so that they cannot be reproduced by a copying machine. As one of them, there is a technique for producing a copy prevention effect and a watermark effect under transmitted light by forming an image using a transparent or translucent substrate.

  For example, a first printed layer, a concealing layer, and a second printed layer are laminated on one side of a transparent or translucent substrate, and an opening that penetrates from the second printed layer to the first printed layer is provided. An anti-counterfeit print medium in which a display unit composed of a dot-like or halftone dot-like pattern is formed is disclosed (for example, see Patent Document 1).

  In the anti-counterfeit print medium described in Patent Document 1, the openings other than the pattern are transparent watermarks that expose the base material. In particular, since a special authenticity determination device is not required and it is possible to easily determine authenticity by visual observation under transmitted light, it has high discrimination between a genuine product and a duplicate product. In addition, it is possible to use an ink containing a magnetic material added to the printing layer, an ink containing two or more kinds of metallic materials, or a combination of various functional inks. It is possible to achieve a further anti-counterfeit effect.

  Other techniques relating to copying and anti-counterfeiting include the use of functional inks that are difficult to reproduce such as color, gloss, or light emission. Functional inks include magnetic inks, fluorescent inks, and infrared absorbing inks that exhibit absorption characteristics in the infrared region. Precious print media using these functional inks are effective for copying on a copier, but for simple characters and designs, if materials are available, they can be forged relatively easily. There is a problem of being able to.

  Therefore, the present applicant not only uses functional ink, but also has a high-definition halftone dot configuration, so that a visible image and a latent image that can be seen only under specific observation conditions can appear. The prevention printed matter is proposed (for example, refer patent document 2).

  The anti-counterfeit printed matter described in Patent Document 2 is a printed matter in which a continuous tone visible image and an invisible image are formed by two types of halftone dot regions, and a plurality of first halftone dot regions are arranged to form a continuous floor. A toned visible image is formed, and the second halftone dot region is printed in an overlapping manner within the first halftone dot region to form a continuous tone invisible image, and the first halftone dot region is an infrared absorbing dye. The second halftone dot region is printed with an ink containing a metal powder or a transfer sheet containing a metal foil.

  With this configuration, a continuous tone image that is visible under a visible light source and a latent image that is visible under infrared light are provided, and a metal material is used in a region for forming the latent image. In general, the color material containing the infrared absorbing dye has a relatively low brightness (high density) design.

  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.

  Further, a planar image of three or more layers is formed in the transparent region, and the transparent region is laminated with a transparent substrate sheet provided with the planar image on one side or both sides. An anti-counterfeit carrier made of an absorbing material and an infrared transmitting material is disclosed (for example, see Patent Document 3).

  Since the anti-counterfeit carrier described in Patent Document 3 is a transparent base sheet, it is possible to visually recognize the planar images formed on the laminated layers in a synthesized state. If a discrimination device capable of reading an infrared image is used, it is possible to confirm only a planar image formed using an infrared absorbing material and an infrared transmitting material.

Japanese Patent Application Laid-Open No. 10-76745 Japanese Patent No. 4500948 Japanese Patent No. 4561248

  However, since the print medium described in Patent Document 1 has an opening that penetrates from the second print layer to the first print layer, a transparent watermark is formed. Although it is possible to easily determine authenticity by checking, the transparent watermark by the opening is a simple pattern, and if the layer configuration is known, it can be forged and imitated relatively easily There was a problem.

  In addition, since the transparent watermark by the opening is a simple pattern and does not form a design having a continuous tone, it is desired to form a design rich in design.

  Furthermore, when confirming a transparent watermark under transmitted light, the pattern and visible information formed on the second printed layer can also be visually recognized together, and cannot be visually recognized as individual images. In other words, since a so-called image switching effect (switching effect) was not achieved, a more advanced anti-counterfeiting technique was demanded.

  The anti-counterfeit printed matter described in Patent Document 2 has two images: a visible image recognizable with visible light and a latent image recognizable using a determination device such as an infrared camera, due to a special halftone dot configuration. Was able to be produced at low cost. However, since the latent image cannot be visually recognized unless a discrimination device such as an infrared camera is used, for example, inspectors in various window operations such as banking or immigration examinations are able to judge authenticity by simple visual inspection. There was a problem that could not be done. Therefore, there is a need for a forgery-preventing printed matter that is provided with a technique capable of determining authenticity by visual observation without using a special determination device in addition to appraisal authenticity determination using a special determination device.

  In addition, the anti-counterfeit carrier described in Patent Document 3 is formed by laminating a transparent base sheet and forming a planar image on each layer, so that each planar image formed on each layer is synthesized. Since the viewing state of the planar image of each layer can be changed by tilting the viewing angle, it is possible to discriminate by visual observation, and at least one planar image is formed. Since the layer is formed using an infrared absorbing material and an infrared transmitting material, by using a discrimination device that can read an infrared image, appraisal authenticity discrimination can also be performed, and visual discrimination and appraisal using a discrimination device However, since the planar image formed on the transparent base sheet is a simple pattern, if the layer configuration is known, Manner easily there is a possibility that the forged.

  Furthermore, for an infrared image that can be viewed under an infrared light source, a planar image of one layer may be formed using an infrared absorbing material and an infrared transmitting material, and the functionality for simply forming an image is improved. Since it has the problem that the same image can be formed if only the material can be obtained, a material having special functionality is temporarily obtained. Even if it is possible, there has been a demand for a highly secure printing medium having a configuration in which the same image or the like cannot be easily formed.

  The present invention aims to solve the above-mentioned problems, and makes it difficult to forge and duplicate by using a precise image line configuration, and it is easy to use under transmitted light without using a special discrimination device. A print medium having a latent image that can be confirmed is proposed. It is another object of the present invention to propose a print medium capable of performing two different types of discrimination, that is, a latent image that can be confirmed using a discrimination device in addition to discrimination under the transmitted light.

  According to the present invention, a transmission latent image region is formed on a part of a substrate made of a transparent material, and the transmission latent image region on the substrate is formed of at least a part of a colorless and / or colored transparent material. Is formed with a concealing layer made of a concealing material for suppressing the permeability of the permeable material, and i) the concealing layer is obtained from the first concealing area ratio to which the concealing material for concealing the transmittance of the substrate is applied. Comprising a first concealing region and a cut-out region that has not been concealed to partially expose the substrate, or ii) the concealing layer is provided with a concealing material that conceals the permeability of the substrate. The first concealment area composed of the first concealment area ratio and the second concealment area composed of the second concealment area ratio lower than the first concealment area ratio are formed on the concealment layer. A plurality of halftone dots and second halftone dots are arranged and displayed. A forming layer is formed, and a plurality of first halftone dots are arranged using a colored material not containing an infrared absorbing dye to form a visible image, and a concealing layer has a cut-out region i) In the case of the above, a second halftone dot is formed in the first halftone dot without colored material, the cutout region and the second halftone dot are arranged at the same position, and a plurality of second halftone dots are arranged. Thus, in the case of ii) in which the first latent image is formed and the concealing layer has the second concealment region, the transmittance is 3% or more by the colored material in the first halftone dot. % Second halftone dots are formed, the second concealment region and the second halftone dot are overlapped at the same position, and a plurality of second halftone dots are arranged to form the first latent image. An image is formed, and the first halftone dot and the second halftone dot are formed to have the same color under reflected light. Under light visible image is visually recognized, a print medium having a transparent latent image, wherein a first latent image pattern when observing the substrate under transmitted light becomes visible.

  In the printing medium having a transmission latent image of the present invention, in the case i) where the concealing layer has a cutout area, the cutout area and the second halftone dot have the same shape and size, or the hiding area is hidden. In the case of ii) where the layer has a second concealment region, the second concealment region and the second halftone dot are characterized by being equal in shape and size.

  The print medium having a transmission latent image of the present invention is characterized in that the second halftone dot is smaller than a certain halftone dot diameter set in the first halftone dot.

  Further, the printing medium having a transmission latent image of the present invention is formed on a substrate that is at least partially made of a colorless and / or colored transmission material and contains an infrared absorbing dye or does not contain an infrared absorbing dye. In the transmission latent image region on the substrate, a concealing layer that does not contain an infrared absorbing dye and is made of a concealing material for suppressing the transmittance of the transmissive material is formed. iii) The concealing layer is not provided with a concealing material in order to expose a part of the substrate, and a first concealing area composed of a first concealing area ratio provided with a concealing material that conceals the permeability of the substrate. Or iv) the concealment layer comprises a first concealment area composed of a first concealment area ratio provided with a concealment material concealing the permeability of the substrate, and a first concealment area ratio. From the low second concealment area ratio An image forming layer is formed by arranging a plurality of first halftone dots, second halftone dots, and third halftone dots on the hidden layer. Forms a visible image by arranging a plurality of colored materials that do not contain an infrared absorbing dye, and the third halftone dot is placed within the first halftone dot by a material containing the infrared absorbing dye. In the case of iii) in which the second latent image is formed and the concealing layer has a cut-out region, the base material contains an infrared-absorbing dye, and the second coloring material is not applied in the third halftone dot. A halftone dot is formed, the cutout area and the second halftone dot are arranged at the same position, and a plurality of second halftone dots are arranged to form a first latent image, or a concealing layer is formed in the first layer. In the case of iv) having two hidden areas, the second halftone dot is the same as the second hidden area in the third halftone dot. When the substrate includes an infrared absorbing dye, the transmittance is 3% or more and 100% or less, and the infrared absorbing dye is included or is formed of a colored color material that does not include, Alternatively, when the substrate does not contain an infrared absorbing dye, the transmittance is 3% or more and 100% or less, and the substrate is formed of a colored color material containing the infrared absorbing dye, and a plurality of second halftone dots are arranged. A latent image is formed, and the first halftone dot, the second halftone dot, and the third halftone dot are formed so as to have the same color under the reflected light. When the visible image is visually recognized, the second latent image is observed when the substrate is observed under an infrared light source, and the first latent image is visible when the substrate is observed under transmitted light. A print medium having a characteristic transmission latent image.

  Further, in the case of the printing medium having a transmission latent image of the present invention in which the concealing layer has a hollow area iii), the hollow area and the second halftone dot are equal in shape and size, or are concealed. In the case of iv) where the layer has a second concealment region, the second concealment region and the second halftone dot are characterized by the same shape and size.

  In the printing medium having a transmission latent image of the present invention, the third halftone dot is smaller than a certain halftone dot diameter set in the first halftone dot, and the second halftone dot is the third halftone dot. It is characterized by being smaller than a certain halftone dot diameter set in the point.

  The print medium having a transmission latent image of the present invention can visually recognize a visible image when observed under reflected light, and can visually recognize the first latent image when the print medium is observed under transmitted light. When the image is observed under an infrared light source, the second latent image can be visually recognized. That is, it is possible to form three images with different viewing conditions on one print medium. In particular, each image can be visually recognized by switching (changing images) under different viewing conditions.

  In addition, since the print medium having the transmission latent image of the present invention can confirm the image under transmitted light, the authenticity determination can be performed by a simple visual method and an infrared image can be acquired. An appraisal technique such as a simple discriminating apparatus is also possible, and both simple discrimination and appraisal discrimination can be performed.

  Furthermore, the print medium having a transmission latent image according to the present invention can be easily produced by a design in which three images overlap in the same area due to a special halftone dot configuration, and is subject to design restrictions. Therefore, a gradation image can be formed.

It is a figure which shows an example of the printing medium which has a permeation | transmission latent image. It is a figure which shows an example of a visible image and a 1st latent image. It is a figure explaining the laminated constitution of the permeable material with respect to a base material. It is a figure for demonstrating the layer structure of a transmission latent image area | region. It is a figure for demonstrating the aspect of the concealment layer in the 1st aspect of 1st Embodiment. It is an example of the top view and schematic diagram which show the transmission latent image area | region in the 1st aspect of 1st Embodiment. It is a figure for demonstrating the relationship of the halftone dot diameter in a halftone dot structure. It is a figure for demonstrating the layer structure of the three layers in the 1st aspect of 1st Embodiment. It is the figure which showed the positional relationship of the printing medium which has the transmission latent image image formed by the 1st aspect of 1st Embodiment, a visible light source, and a viewpoint. It is a graph which shows color difference (DELTA) E of each 1st halftone dot and 2nd halftone dot under reflected light and under transmitted light. It is the top view and schematic diagram at the time of visually recognizing the printing medium formed by the 1st aspect of 1st Embodiment under the reflected light under the visible light source of a fixed position. It is the top view and schematic diagram at the time of visually recognizing the printing medium formed by the 1st aspect of 1st Embodiment under the transmitted light under the visible light source of a fixed position. It is a schematic diagram which shows the structure of the concealment layer of the 2nd aspect of 1st Embodiment. It is a schematic diagram which shows the structure of the image forming layer of the 2nd aspect of 1st Embodiment. It is a figure for demonstrating the layer structure of the three layers of the 2nd aspect of 1st Embodiment. It is a schematic diagram which shows the structure of the image forming layer of the 3rd aspect of 1st Embodiment. It is a figure for demonstrating the layer structure of the three layers of the 3rd aspect of 1st Embodiment. It is a figure for demonstrating the aspect of the concealment layer in the 1st aspect of 2nd Embodiment. It is an example of the top view and schematic diagram which show the transmission latent image area | region of 2nd Embodiment. It is a figure for demonstrating the layer structure of the three layers in the 1st aspect of 2nd Embodiment. It is a graph which shows an example of the spectral transmittance of white ink and magenta ink. It is a graph which shows an example of the spectral reflectance of PET film, white ink, magenta ink, and black ink. It is the top view and schematic diagram at the time of visually recognizing the printing medium formed by the 1st aspect of 2nd Embodiment under the reflected light under the visible light source (R) of a fixed position. It is the top view and schematic diagram at the time of visually recognizing the printing medium formed by the 1st aspect of 2nd Embodiment under the transmitted light under the visible light source of a fixed position. It is the top view and schematic diagram at the time of observing the printing medium formed by the 1st aspect of 2nd Embodiment through apparatuses, such as an infrared display device, under the infrared light source of a fixed position. It is a figure for demonstrating the aspect of the concealment layer in the 2nd aspect of 2nd Embodiment. It is a schematic diagram which shows the structure of the image forming layer of the 2nd aspect of 2nd Embodiment. It is a figure for demonstrating the layer structure of the three layers in the 2nd aspect of 2nd Embodiment. It is a schematic diagram which shows the structure of the image forming layer of the 3rd aspect of 2nd Embodiment. It is a figure for demonstrating the layer structure of the three layers in the 3rd aspect of 2nd Embodiment. 3 is a diagram for explaining a layer configuration of three layers in Example 1. FIG. It is a figure explaining the certificate of Example 2. FIG. It is a figure which shows the visible image in Example 2, a 1st latent image, and a 2nd latent image. 6 is a diagram for explaining a layer configuration of three layers in Example 2. FIG.

  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 print medium (1) (hereinafter referred to as “print medium”) having a transmission latent image in the present invention. As shown in FIG. 1A, the print medium (1) has a transmission latent image region (2) in which a transmission latent image according to the present invention is formed at least partially.

  The print medium (1) can visually recognize a visible image (3) as shown in FIG. 2 (a) under reflected light under a visible light source, and FIG. The first latent image (4) as shown in b) can be visually recognized. The principle of visual recognition of these two images will be described later. The reflected light includes diffused light and regular reflected light. The reflected light in the present invention refers to diffused light. (Hereafter referred to as “reflected light”)

  The transmission latent image region (2) is composed of three layers as shown in FIG. 1 (b) which is a cross-sectional view of the print medium (1). The transmission latent image region (2) may be formed on a part of the print medium (1) as shown in FIG. 1, but the entire surface of the print medium (1) is formed as the transmission latent image region (2). You may do it. For the three layers constituting the transmission latent image region (2), the base material (7), the concealing layer (8), and the image forming layer (9) are formed in order from the bottom layer. ing.

  First, the three layers will be described. The substrate (7) is not particularly limited as long as at least a part thereof is made of a colorless and / or colored transparent material (6), and paper sheets such as fine paper, coated paper and art paper A film or the like can be used, and the transmittance of the permeable material (6) is in the range of 3% to 100%. As the colorless (transparent) transparent base material, there is a transparent film formed of a material such as PET or vinyl chloride. In addition, as the colored transparent base material, there are those obtained by adding coloring components such as dyes and pigments to the above-mentioned colorless (transparent) PET film and the like, and transparent colored inks and colored films are laminated. It may be formed.

  The layer structure of the base material (7) made of the permeable material (6) will be described with reference to FIG. For example, FIG. 3A shows a single layer structure made of a colorless (transparent) transparent material (6a), and FIG. 3B shows a single layer structure made of a colored transparent material (6b). 3 (c) shows a two-layer structure composed of a colorless (transparent) transparent material (6a) and a colored transparent material (6b), and FIG. 3 (d) shows a colored transparent material (6b). ) And a colored transparent material (6b ′), FIG. 3 (e) shows a colored transparent material (6b), a colored transparent material (6b ′) and a colorless (transparent) A three-layer structure composed of a permeable material (6a), in which a colorless (transparent) transmissive material (6a) is a lower layer, and FIG. 3 (f) is a three-layer structure of FIG. 3 (e). The colorless (transparent) transparent material (6a) is arranged in the intermediate layer, and FIG. 3 (g) shows a colored transparent material (6b) in which only the intermediate layer is colored. FIG. 3 (h) shows a four-layer structure in which a colored transparent material (6b), a colored transparent material (6b ′), and a colorless (transparent) transparent material (6a) are two layers. Layer structure.

  Further, a transparent metallic glossy film (such as PICASUS manufactured by Toray Industries, Inc.) may be used for the base material (7). The metallic glossy film is a polyester film formed by laminating different kinds of polymers and is a transmissive material capable of obtaining a metallic gloss without using a metal.

  In FIG. 1B, the entire surface of the print medium (1), that is, the base material itself is described as being formed of a transparent material. However, the base material (7) of the present invention is not limited to this. Alternatively, a part of the base material (7) may be formed of a permeable material.

  For example, as shown in FIG. 4, the transmissive material (6) may be formed only in a portion corresponding to the transmission latent image region (2).

  Next, the concealment layer (8) which is the second layer will be described. The concealing layer (8) is formed on the base material (7) formed of the permeable material (6) described above, and plays a role in suppressing the permeability of the base material (7) which is the lower layer. The hiding layer (8) needs to have a color that does not affect the visible image (3) formed by the image forming layer (9) formed on the hiding layer (8). Therefore, although the concealing layer (8) can use white ink or the like, it is a concealing material capable of suppressing the transparency of the base material (7) and affects the visible image (3) of the image forming layer (9). The material is not particularly limited as long as the material does not give any. In the present embodiment, a description will be given of a mode in which a concealing layer is formed using white ink. Examples of the white ink used as the concealment material include 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.

  FIG. 5A is a schematic diagram in which a part of the concealment layer (8) is enlarged, and the concealment layer (8) corresponds to a third image forming layer (9) described later. , Formed from one region. As described above, this region has a role of concealing the transparency of the base material (7) as a lower layer, and is therefore defined as a first concealment region (11) having a first concealment area ratio. Moreover, the area | region which does not form a concealment material is defined as a hollow area | region (10), and since the concealment material is not formed in this hollow area | region (10), it will be in the state which the base material (7) exposed. In addition, the description about the concealment area ratio is mentioned later.

  The positional relationship, shape, and size of the first concealment region (11) that constitutes the concealment layer (8) correspond to the halftone dot configuration of the image forming layer (9). The corresponding relationship between the concealment layer (8) and the image forming layer (9) will be described when explaining the visual recognition principle described later.

  Next, the cutout region (10) will be described. The cutout region (10) is formed in the first concealment region (11), and the cutout region (10) is cut out as shown in FIG. 5 (b), which is an (enlarged) cross-sectional view taken along line X1-X2 of FIG. 5 (a). In the region (10), white ink is not applied. Therefore, when the print medium (1) is observed from above, the base material (7) under the concealment layer (8) can be confirmed from the cutout region (10).

  This cut-out area (10) is also arranged corresponding to the halftone dot configuration of the image forming layer (9) described later, and in the present invention, a first latent image that can be confirmed under transmitted light is formed. Has become an important role for. The positional relationship with the image forming layer (9) will be described later.

  Next, the image forming layer (9) which is the third layer will be described. The image forming layer (9) forms a visible image (3) including a continuous tone image visible under reflected light under a visible light source by halftone dots. Therefore, the halftone dot configuration of the image forming layer (9) will be described with reference to FIG. Note that the visible image (3) including the continuous tone image may be a binary image having no continuous tone.

(First aspect of the first embodiment)
FIG. 6 is an example of a plan view and a schematic view showing the transmission latent image region (2) of the first aspect of the first embodiment. The print medium (1) of the present invention is a visible image (3) and a latent image on at least a part of a transmission latent image region (2) on a base material (7) made of a transparent material such as a plastic card. The first latent image (4) is formed by printing. The visible image (3) is mainly formed by commonly used cyan (C), magenta (M), yellow (Y) and black (Bk) inks. The visible image (3) is generated by arranging two images composed of halftone dots on the same plane so as to overlap each other with a special halftone dot configuration. A special halftone dot configuration will be described later.

  In the transmission latent image area (2) shown in FIG. 6A, a visible image (3) and a first latent image (4) which is a latent image are formed. The first latent image (4) is embedded in the visible image (3), and the visible image (3) is visually recognized under reflected light under a visible light source. One latent image (4) can be visually recognized. The transmission latent image region (2) of the present invention shown in FIG. 6A has an observation condition under the reflected light under the visible light source (hereinafter referred to as “first observation”) by the halftone dot configuration shown in FIG. Different patterns can be visually recognized according to an observation condition (hereinafter referred to as “second observation condition”) in which the substrate (7) is seen through the light source under a visible light source.

  When the transmission latent image region (2) shown in FIG. 6 (a) is observed under the first observation condition, the visible image (3) can be visually recognized as shown in FIG. 6 (c1). Is possible. When the substrate (7) is seen through the visible light source under the visible light source, that is, when the transmission latent image region (2) shown in FIG. 6 (a) is observed under the second observation condition. As shown in FIG. 6 (c2), it is possible to visually recognize the first latent image (4). As described above, the visible image (3) shown in FIG. 6A has different patterns that appear by changing the observation conditions. The visual recognition principle will be described later.

  Here, the halftone dot configuration will be described with reference to the schematic diagram of FIG. As shown in FIG. 6 (b), the visible image (3) has a first halftone dot (14) as an image forming layer (9) on the concealing layer (8) formed on the substrate (7). And a second halftone dot (15).

  First, the first halftone dot (14) will be described. This 1st halftone dot (14) is a halftone dot which forms the visible image (7) visually recognizable on 1st observation conditions. A plurality of the first halftone dots (14) are arranged, and a continuous tone visible image (3) can be formed according to the size of the halftone dots.

  In the first halftone dot (14), the second halftone dot (15) is arranged so as to overlap. The visible image (3) is formed by changing the size of each halftone dot. In addition, the arrangement | positioning location of the 1st halftone dot (14) in the visible image (3) and the 2nd halftone dot (15) is not limited to this.

  FIG. 6C1 is a diagram illustrating an example of a visible image (3) and a first halftone dot (14) that forms the visible image. A plurality of first halftone dots (14) are arranged to form a visible image (3) that is visible under the first observation condition. The visible image (3) is partially different in size at the first halftone dot (14) to form a Gothic “NPB” character and its background image. The first halftone dot (14) is formed using a colored color material.

  In the first embodiment, the second halftone dot (15) is formed in the first halftone dot (14). The first halftone dot (14) and the second halftone dot (15) are visually recognized in the same color under the first observation condition, so that only the first halftone dot (14) is visible. Thereby, only the visible image (3) composed of the first halftone dot (14) can be visually recognized under the first observation condition.

  The color matching in the present invention means that the color difference ΔE is less than 6. In general, when the color difference ΔE is around 6, there is a possibility that it is visually recognized as a different hue. However, as described above, in the present invention, the first halftone dot (14) and the second halftone dot (15) are configured by the size of halftone dots that cannot be visually recognized by the naked eye. ing. Therefore, as described above, if the color difference ΔE is less than 6, the second halftone dot (15) cannot be visually recognized under the first observation condition, and the first halftone dot (14) and the first halftone dot (14) The halftone dot (15) is visually recognized as the same color.

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 color difference ΔE changes, for example, by producing a printing ink and applying it as a printing part on a base material using a transmissive material to produce the printing medium A. Similarly, a printing ink is prepared and applied as a printing portion on a base material using a non-permeable material to prepare a printing medium B. Let e be the color difference ΔE between the print medium A and the print medium B under reflected light under an illumination light source placed at a fixed position.
Next, the color difference ΔE between the print medium A and the print medium B under transmitted light is measured under an illumination light source in which the print medium A and the print medium B are installed at fixed positions. If the measured color difference ΔE is a value different from e described above, the color difference ΔE has changed.

  Note that due to metamerism, when viewed under reflected light under a visible light source, the color visually recognized by the naked eye is viewed as a different color when observed under reflected light under a specific light source. Even in this case, in the present invention, it is assumed that the first halftone dot (14) and the second halftone dot (15) are formed in the same color.

  Next, the second halftone dot (15) will be described. The second halftone dot (15) is a halftone dot that forms a first latent image (4) that is visible under a transmitted light under a visible light source. A continuous tone first latent image (4) can be formed by the size of the second halftone dot (15).

  FIG. 6C2 is a diagram illustrating an example of the first latent image (4) and the second halftone dot (15) that forms the first latent image. The second halftone dot (15) is visible under the so-called second observation condition shown in FIG. 6 (c2), in which the base material (7) is viewed through the light source under a visible light source. This is an area for forming the first latent image (4). The second halftone dot (15) is arranged so as to overlap with the first halftone dot (14). In the second halftone dot (15), three characters of “NPB” in the Mincho style and its background are formed by making the sizes partially different within a predetermined range.

  The second halftone dot (15) is made smaller than a certain halftone dot diameter set in the first halftone dot (14). The constant halftone dot diameter is the minimum size among the plurality of first halftone dots (14) arranged, and the second halftone dot (15) is the first halftone dot (14). Form in a range not exceeding the minimum size.

  FIG. 7 is a diagram showing an example in which the size of the second halftone dot (15) is changed. FIG. 7A and FIG. 7B show a first halftone dot (14) and a second halftone dot (15) having different sizes.

  The first halftone dot (14) shown in FIG. 7B has the smallest halftone dot diameter at the first halftone dot (14), and its diameter is L. Therefore, the maximum size of the second halftone dot (15) is formed in a range not exceeding the diameter L which is the minimum size of the first halftone dot (14). In FIG. 7A, the minimum size (F) of the first halftone dot (14) is indicated by a dotted line.

  If the second halftone dot (15) is formed exceeding the minimum size (F) of the first halftone dot (14), the second halftone dot (15) is formed with respect to the visible image (3). This is because the first latent image (8) is affected, and a clear visible image (3) cannot be formed.

  FIG. 6B shows a state in which the above-described first halftone dot (14) and second halftone dot (15) are overprinted on the print medium (1). The maximum diameter of the second halftone dot (15) is less than or equal to the minimum diameter of the first halftone dot (14). Thereby, the second halftone dot (15) can be arranged at any position within the first halftone dot (14).

  In the first aspect of the first embodiment, the second halftone dot (15) is not printed, and the so-called second halftone dot (15) is cut out. By doing so, the second halftone dot (15) in the actual print medium (1) can pass through the cutout area (10) where the concealing material is not printed and the second element (15) through the substrate ( 7) can be confirmed, and as a result, the second halftone dot (15) is formed of the permeable material (6).

  FIG. 8 shows the configuration. As shown in FIG. 8A, the halftone dot configuration is the same as that described above when confirmed from above, and the second halftone dot (15) is arranged in the first halftone dot (14). Has been. As shown in FIG. 8B, a concealing layer (8) made of a concealing material is formed on a transparent base material (7), and an image forming layer (for example, printing ink) is formed on the concealing layer (8). 9) is formed. However, the second halftone dot (15) has no color material (for example, printing ink). In the second halftone dot (15) having no coloring material (for example, printing ink) and the concealing layer (8), the cutout region (10) to which the concealing material is not applied is arranged at the same position. Yes.

  In FIG. 8B, FIG. 8C shows a cross-sectional view at X1-X2. As shown in FIG. 8B, the second halftone dot (15) is not printed on the image forming layer (9), and at the same time, a part of the second hiding layer (8) is also hidden. It is a hollow region (10) where no material is applied. The cutout area (10) to which no concealing material is applied has the same size and the same shape as the second halftone dot (15).

  The reason why the concealing material is printed on the transparent base material (7) is that it does not affect the visibility of the visible image (3), and thus has a role of concealing the transparency. .

(Image viewing principle in the first embodiment)
Under the first observation condition, the first halftone dot (14) and the second halftone dot (15) can be seen as the same color, so that the first latent image (4) can be seen. On the contrary, the first latent image (4) is configured to be visible under the second observation condition. Generally, the color of an object is determined by the light source, the observation environment (temperature), the spectral reflectance of the object, and the like. Although the way of visually recognizing colors varies depending on these observation conditions, in the present invention, the observation conditions are assumed to be constant conditions (for example, observation conditions: the light source is D65, the observation environment is 20 ° C., etc.).

  FIG. 9 shows the visible light source (R) and the viewpoints (E1, E2) when the observation position of the print medium (1) according to the present invention is observed with reflected light or transmitted light with respect to the visible light source (R) at a fixed position. And a positional relationship between the print medium (1). When the visible light source (R), the viewpoint (E1), and the print medium (1) are in the positional relationship shown in FIG. 9A, the observation is performed under the so-called first observation condition that is reflected light. Further, when the visible light source (R), the viewpoint (E2), and the print medium (1) are in the positional relationship shown in FIG. 9B, the observation is performed under the so-called second observation condition that is transmitted light. Become.

  Next, the principle that the color difference ΔE between the first halftone dot (14) and the second halftone dot (15) changes by a predetermined value due to the change in the observation position will be described. As described above, the reflected light in the present invention is a position 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 transmitted light is the fixed position. The print medium (1) is placed on a straight line connecting the illumination light source and the viewpoint (E2), and the print medium (1) is viewed through the illumination light source in a transparent manner. In the print medium (1), the first halftone dot (14) and the second halftone dot (15) are the same color in the positional relationship meaning the reflected light shown in FIG. Only the visible image (3) is visually recognized without distinguishing the region.

  On the other hand, in the transmitted light shown in FIG. 9B, the second halftone dot (15) is formed of a base material (7) using a transmissive material. Accordingly, by changing the observation position from the first observation condition to the second observation condition with respect to the illumination light source at the fixed position, the brightness and / or color changes, and the first halftone dot (14) and the first The color difference ΔE of the halftone dot (15) changes to a predetermined value. Therefore, the second halftone dot (15) becomes visible and the first latent image (4) becomes visible.

  FIG. 10 is a graph showing the color difference ΔE between the first halftone dot (14) and the second halftone dot (15) under reflected light or transmitted light according to the present invention. FIG. 10 shows the color difference ΔE between the first halftone dot (14) and the second halftone dot (15) under reflected light, and the right side of FIG. 10 shows the first halftone dot (14) and the second halftone dot under transmitted light. The color difference ΔE of the halftone dot (15) is shown. Note that the halftone dot configuration in FIG. 10 is the same as the halftone dot configuration in FIG.

  As a measurement sample, first, measurement sample A (4 × 4 cm) has a second halftone dot (15) in a circular shape with a line number of 45 and a halftone dot diameter (diameter) of 280 μm. On the PET film having a thickness of 2 mm, the hollow region (10) in the first concealment region (11) as the concealment layer (8) has the same number of lines and dot diameter as the second halftone dot (15). Using white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.), only the first concealed area (11) is solid-printed by inkjet printing, and the first halftone dot (9) is formed as an image forming layer (9). The second halftone dot (15) was printed by inkjet printing without printing 14).

  In addition, the measurement sample B (4 × 4 cm) has a first halftone dot (14) of a circular shape with a line number of 45 and a halftone dot diameter (diameter) of 280 μm, and the substrate (7) has a thickness of 0.2 mm. Using a white ink (LIOJET FV03 White, manufactured by Toyo Ink Manufacturing Co., Ltd.) on the PET film having the above structure, only the first concealment region (11) is present as the concealment layer (8) (there is no hollow region (10)). The solid ink is printed by inkjet printing, and the second halftone dot (15) is not printed as the image forming layer (9), and the first halftone dot (14) is processed with process ink (LIOJET FV03 Black, manufactured by Toyo Ink Manufacturing Co. ) Using inkjet printing.

  The color difference ΔE between the first halftone dot (14) and the second halftone dot (15) under the reflected light shown in FIG. 10, and the first halftone dot (14) and the second halftone dot under the transmitted light shown in FIG. The color difference ΔE of the halftone dot (15) is determined by using the self-recording spectrophotometer (U-4000 type manufactured by HITACHI) to determine the spectral reflectance and spectral transmittance of the measurement sample A and measurement sample B at wavelengths of 400 to 700 nm. The color difference ΔE was calculated from the measured value.

  As shown in FIG. 10, under reflected light, the color difference ΔE between the first halftone dot (14) and the second halftone dot (15) shows a relatively small value of 1.11. . As described above, if the color difference ΔE is less than 6, the colors are the same color, and therefore the first halftone dot (14) and the second halftone dot (15) can be said to be the same color under reflected light. Therefore, it is difficult to identify the first halftone dot (14) and the second halftone dot (15) with the naked eye, and as a result, the first latent image formed in the transmission latent image region (2). The image image (4) cannot be visually recognized.

  Conversely, under the transmitted light shown in FIG. 10, the color difference ΔE between the first halftone dot (14) and the second halftone dot (15) is 6.15. The color difference ΔE between the first halftone dot (14) and the second halftone dot (15) under reflected light is 1.11, while the first halftone dot (14) and the second halftone dot in the transmitted light are The color difference ΔE from the halftone dot (15) is 6.15. That is, by changing the observation position from below reflected light to below transmitted light, the color difference ΔE changes by 5.04 from 1.11 to 6.15. Therefore, when the color difference ΔE changes by 5 or more, the first halftone dot (14) and the second halftone dot (15) can be identified with the naked eye, and as a result, in the transmission latent image region (2). It is possible to visually recognize the first latent image (4) formed on the.

  Note that, under the same observation conditions, the first observation condition and the second observation condition can be switched by changing the observation position with respect to the visible light source (R). That is, the first halftone dot (14) and the second halftone dot (15) can be identified by seeing the base material (7) through the visible light source (R). As a result, the first latent image (4) formed in the transmission latent image region (2) can be visually recognized.

(Visual image viewing principle)
FIG. 11 is a plan view and a schematic view when the transmission latent image region (2) of the print medium (1) according to the present invention is visually recognized under the first observation condition. In the transmission latent image region (2) shown in FIG. 11 (a1), as shown in FIG. 11 (a2), the first halftone dot (14) is visible under the first observation condition. That is, the visible image (3) can be visually recognized. The second halftone dot (15) cannot be distinguished by being visually recognized in the same color as the first halftone dot (14) in the first observation condition. The formed first latent image (4) cannot be visually recognized.

  FIG. 11B is a schematic diagram when the print medium (1) is visually recognized under the first observation condition. The viewing principle of the visible image (3) under the first viewing condition will be described with reference to FIG. When the print medium (1) is visually recognized under the first observation condition, first, the first halftone dot (14) is reflected by the incident light (R1) from the visible light source (R) and the specularly reflected light. Diffused light (R2) is generated, and diffused light (R2) is obtained as reflected light.

  For the second halftone dot (15), incident light (R1) from the visible light source (R) generates specularly reflected light and diffused light (R3), and diffused light (R3) is obtained from the reflected light. It is done. Since the first halftone dot (14) and the second halftone dot (15) are formed so as to have the same color when observed under the first observation condition, the difference in reflected light in each region is determined. I can't confirm.

  Under the first observation condition, the intensity of the reflected light of the visible image (3) and the first latent image (4) is substantially constant. Therefore, the second halftone dot (15) is arranged so as to overlap the first halftone dot (14), and the first halftone dot (14) is more halftone than the second halftone dot (15). By increasing the diameter, the first latent image (4) is hidden in the visible image (3). Therefore, when the print medium (1) is observed under the first observation condition, only the visible image (3) composed of the first halftone dot (14) can be visually recognized, and the second halftone dot. The first latent image (4) composed of (15) cannot be visually recognized.

(First latent image image viewing principle)
FIG. 12 is a plan view and a schematic view when the transmission latent image region (2) of the print medium (1) is visually recognized under the second observation condition. In the transmission latent image region (2) shown in FIG. 12 (a1), as shown in FIG. 12 (a2), the second halftone dot (15) is visible under the second observation condition. That is, the first latent image (4) can be visually recognized. The second halftone dot (15) can be distinguished from the first halftone dot (14) because the color difference ΔE changes and is visually recognized under the second observation condition. The first latent image (4) formed in 15) can be visually recognized.

  The visual recognition principle of the first latent image (4) under the second observation condition will be described with reference to FIG. When the print medium (1) is visually recognized under the second observation condition, first, the transmitted light is transmitted to the first halftone dot (14) by the incident light (R1) from the visible light source (R). (R4) is obtained. Further, transmitted light (R5) is obtained at the second halftone dot (15) forming the first latent image (4).

  Therefore, the second halftone dot (15) is formed of the transmissive material (6), and the transmitted light (R5) of the second halftone dot (15) is transmitted through the first halftone dot (14). The first latent image is the first latent image because the color difference ΔE becomes brighter than the light (R4) and the lightness difference makes it possible to distinguish between the first halftone dot (14) and the second halftone dot (15). The image (4) can be visually recognized. Therefore, under the second observation condition, when the print medium (1) is observed, the first latent image (4) can be visually recognized anew.

(Second aspect of the first embodiment)
Next, another embodiment of the present invention will be described. However, the base material (7) which is the first layer is the same as the first aspect of the first embodiment, and will be omitted. In addition, the second layer, the concealment layer (8) and the third layer, the image forming layer (9), also partially overlap with the first aspect of the first embodiment. It will be omitted.

  The second aspect of the first embodiment differs from the first aspect of the first embodiment in that the concealed layer (8) and the image forming layer (9) are hollowed out in the respective layers. The latent image is formed by the difference in the hidden area ratio and the transmittance.

  First, the layer structure in the concealment layer (8) will be described with reference to FIG. Since the concealing layer (8) plays the role of concealing the transparency of the substrate (7), as in the first aspect of the first embodiment, it is formed using white ink. However, although white ink is printed also in the portion corresponding to the cutout region (10) in the first aspect of the first embodiment, it is lower than the concealment area ratio of the first concealment region (11). The region is defined by a concealment area ratio, and this region is defined as a second concealment region (12). The first concealment region (11) is formed with the first concealment area ratio, and the second concealment region (12) is formed with the second concealment area ratio.

  Therefore, the relationship between the first hidden area ratio and the second hidden area ratio of the first hidden area (11) and the second hidden area (12) constituting the hidden layer (8) is as follows. It becomes. However, since it is necessary for the second concealment region (12) to be accompanied by the transparency of the base material (7) in the lower layer in the transmitted light, the second concealment area ratio is in the range of 0% or more and less than 100%. It is necessary to.

  Moreover, since it is necessary for the 1st concealment area | region (11) to suppress the transmittance | permeability of the base material (7) of a lower layer in the transmitted light, about 1st concealment area ratio is larger than 0% and 100% or less. It is necessary to be in the range. As described above, the second concealment region (12) is defined separately from the cutout region (10) in the first aspect of the first embodiment by printing white ink. The second concealed area ratio may be 0%. For example, as in the first aspect of the first embodiment, the first concealment area ratio of the first concealment region (11) is 100%, and the second concealment area of the second concealment region (12). The rate may be 0%.

  By making the second concealed area (12) have a concealed area ratio lower than that of the first concealed area (11), it is possible to visually recognize the transparency in the base material (7) under transmitted light as described above. Therefore, the first latent image (4) is formed by arranging a plurality of second concealment regions (12). Note that even when the first hidden area ratio and the second hidden area ratio are set to be approximately 0% or 0%, that is, even when the hidden layer (8) is substantially omitted, the second printed matter is used as the printed matter. If the transmittance of the concealment region (12) (second halftone dot (15)) is higher than that of the first concealment region (11) (first halftone dot (14)), the first observation under the second observation condition is performed. The latent image (4) is visible. However, if the first hidden area ratio and the second hidden area ratio are approximated, the visibility of the first latent image (4) under the second observation condition may be reduced. It is necessary to appropriately set the rate and the second concealed area rate.

  Here, the concealment area ratio is the ratio of the area where the concealment material is formed per unit area of the first concealment region (11) or the second concealment region (12) in the concealment layer (8). For example, in the second concealment region (12), the second concealment area ratio of 80% means that the ratio of the area in which the concealment material is formed in the second concealment region (12) is 80%.

  Therefore, the second concealed area ratio is made lower than the first concealed area ratio by lowering the concealed area ratio, so that the ratio of concealing the base material (7) as the lower layer is reduced. A decrease in the permeability of the second concealment region (12) is suppressed as compared with the concealment region (11). That is, when the print medium (1) is changed from the reflected light to the transmitted light with respect to the illumination light source at the fixed position, the first of the image forming layer (9) corresponding to the first concealment region (11). The transmitted light of the second halftone dot (15) of the image forming layer (9) corresponding to the second concealed region (12) is higher than the transmitted light of the halftone dot (14). This is because the visibility of the first latent image (4) under the observation conditions is not lowered.

  Further, by forming a concealment material in the second concealment region (12), the brightness (intensity) of the transmitted light of the first concealment region (11) and the transmitted light of the second concealment region is approximated, There is also a possibility that the visibility of the first latent image (4) under the second observation condition is lowered. Therefore, the second concealment area ratio of the second concealment region (12) needs to be set as appropriate while paying attention to the transmitted light of the second concealment region (12).

  Next, the image forming layer (9) in the second aspect of the first embodiment will be described. About this image formation layer (9), similarly to the first aspect of the first embodiment, a visible image (3) that is visible under the first observation condition is formed. ) Is the same as the first aspect of the first embodiment.

  In the first aspect of the first embodiment, a hollow region formed in the concealment layer (8) in the first halftone dot (14) in order to form the first latent image (4). The second halftone dot (15) is formed in the same position as (10), but the second aspect of the first embodiment is the same as that of the first embodiment. The portion corresponding to the hollowed second halftone dot (15) in the first aspect is not hollowed, but formed with an ink layer having a high transmittance, accompanied by the permeability of the base material (7) as the lowermost layer. I will let you.

  For the second halftone dot (15) in the image forming layer (9), there are two formation methods. First, as the second aspect of the first embodiment, FIG. The second will be described as a third aspect of the first embodiment described later.

  As shown in FIG. 14, the image forming layer (9) includes a first halftone dot (14) for forming a visible image (3) and a first dot for forming a first latent image (4). The location having two halftone dots (15) is the same as the first aspect of the first embodiment. However, as described above, in the first halftone dot (14), the second halftone dot (15) for forming the first latent image (4) is the first halftone dot (14). Cannot be distinguished.

  In FIG. 14 (a), in order to show the positional relationship with the first hidden area (11) and the second hidden area (12) in the lower layer, it is illustrated by an image line in the first halftone dot (14). However, as shown in FIG. 14B as a cross-sectional view, there is actually no region corresponding to the second halftone dot (15) in the first halftone dot (14). However, since the area illustrated by the image line is an area for forming the first latent image (4) in the second aspect of the first embodiment, The second halftone dot (15) is defined as in the first aspect of the form.

  The second halftone dot (15) is entirely constituted by the first halftone dot (14) in the first aspect of the first embodiment. However, the transmittance is such that the transparency of the lowermost base material (7) can be visually recognized under the transmitted light through the second concealment region (12) in the concealment layer (8) as the lower layer. There is a need. Therefore, the transmittance of the second halftone dot (15) needs to be in the range of 3% to 100%.

  Further, in order to make the second halftone dot (15) incapable of visually recognizing the first latent image (4) under the first observation condition, the concealment layer (8) under the first observation condition. ) So that the colors of the base material (7) visible through the second concealment region (12) and the first concealment layer (8) in the concealment layer (8) are the same color. A halftone dot (15) needs to be formed. Therefore, in the first observation condition, the first halftone dot (14) and the second halftone dot (15) are formed so as to have the same color.

  Next, FIG. 15 illustrates the layer structure in the second mode of the first embodiment. As shown in FIG. 15A, the halftone dot configuration is the same as that of the above-described embodiment when confirmed from above, and the second halftone dot (15) is included in the first halftone dot (14). ) Is arranged. As shown in FIG. 15 (b), the first concealment region (11) of the concealment layer (8) formed on the substrate (7) and the image formation layer (9) of the concealment layer (9) formed on the first concealment region (8). One halftone dot (14) is disposed at the same position, and the second halftone dot (15) of the image forming layer (9) is disposed within the first halftone dot (14). Similarly, the second concealment region (12) and the second halftone dot (15) are arranged at the same position. As shown in FIG. 15C, the second latent area (12) formed in the concealment layer (8), which is the area where the first latent image (4) is actually formed, is actually formed. Is formed so that the first halftone dot (14) and the second halftone dot (15) have the same color under the first observation condition, and the second halftone dot having a transmittance of 3% to 100%. Point (15) is located.

  With the layer configuration shown in FIG. 15, as in the first aspect of the first embodiment, under the first observation condition, the first halftone dot (14) of the image forming layer (9) The formed visible image (3) is visually recognized. Then, when the print medium (1) is watermarked with respect to the light source, the second concealment area (with a concealment area ratio lower than the first concealment area (11) via the second halftone dot (15) ( The second halftone dot (15) is formed by being able to confirm the base material (7) further through 12), and the second halftone dot (15) is formed by arranging a plurality of second halftone dots (15). One latent image (4) can be visually recognized.

(Third aspect of the first embodiment)
Next, as a third aspect of the first embodiment, in addition to the first forming method in the image forming layer (9) described above, the second forming method of the second halftone dot (15). Will be described with reference to FIG. The first halftone dot (14) is the same as the image forming layer (9) (second aspect of the first embodiment) described above, but the second halftone dot (15) It forms in the location applicable to the same position as the 2nd concealment area | region (12) formed in the concealment layer (8). Therefore, the first halftone dot (14) and the second halftone dot (15) are formed by two colors. The second halftone dot (15) is formed in the range of transmittance of 3% to 100%. If it is lower than this range, the transparency of the lowermost substrate (7) cannot be confirmed.

  As described above, the second concealment region (12) formed in the concealment layer (8) has a concealment area ratio so low that the permeability of the base material (7) can be confirmed. By forming the transmittance of the halftone dot (15) high, the permeability of the lowermost base material (7) is the second observation condition through the second concealment region (12) as the lower layer. It becomes possible to confirm. However, in order to make the first latent image (4) invisible under the first observation condition, the first halftone dot (14) and the second halftone dot (15) Under the conditions, they are formed so as to have the same color.

  FIG. 17 illustrates the layer configuration of the third aspect in the first embodiment. As shown in FIG. 17A, the halftone dot configuration is the same as that of the above-described embodiment when confirmed from above, and the second halftone dot (14) is included in the first halftone dot (14). 15) is arranged. As shown in FIGS. 17B and 17C, the first concealment region (11) of the concealment layer (8) formed on the substrate (7) and the image forming layer (9) formed thereon ) First halftone dot (14) is arranged at the same position.

  With the layer configuration shown in FIG. 17, as in the first aspect and the second aspect in the first embodiment, the first image forming layer (9) has the first observation condition under the first observation condition. The visible image (3) formed by the halftone dots (14) is visually recognized. Then, when the print medium (1) is observed under the second observation condition, the second concealment region having a concealment area ratio lower than that of the first concealment region (11) through the second halftone dot (15). Since the substrate (7) can be confirmed further through (12), the second halftone dot (15) is formed, and the second halftone dot (15) is formed by being arranged in plural. The first latent image (4) can be visually recognized.

  The third aspect of the first embodiment is characterized in that a hollow region is not formed in each of the concealing layer (8) and the image forming layer (9), but the concealing layer (8) or A cutout region may be formed in either one of the image forming layers (9).

(First aspect of the second embodiment)
Next, another embodiment of the present invention will be described. The base material (7) which is the first layer is omitted because it is the same as that of the first embodiment, but in the first aspect of the second embodiment, the first layer under transmitted light is omitted. In addition to the visual effect of one latent image, the visual effect of the second latent image under an infrared light source is achieved. The observation state under the infrared light source is hereinafter referred to as “third observation condition”. Therefore, the base material (7) is preferably formed of a transmissive material containing an infrared absorbing dye, and a specific description thereof will be described later.

  FIG. 18A is an enlarged schematic view of a part of the concealment layer (8), which is the second layer. The concealment layer (8) is the first aspect of the first embodiment. Similarly to the above, the first concealment region (11) formed of the concealment material is provided so as to correspond to the uppermost image forming layer (9). Moreover, it has the hollow area | region (10) which does not form a concealment material, and since the concealment material is not formed in the hollow area | region (10), it is in the state which the base material (7) exposed.

  FIG. 19 is an example of a plan view and a schematic view showing a transmission latent image region according to the first aspect of the second embodiment. As shown in FIG. 19A, the print medium (1) of the present invention is similar to the first embodiment in that at least part of the transmission medium on the base material (7) made of a transparent material such as a plastic card is transmitted. A visible image (3) is formed in the latent image region (2) by printing.

  In the transmission latent image area (2) shown in FIG. 19A, a visible image (3), a first latent image (4) and a second latent image (5) which are latent images are formed. Has been. By embedding the first latent image (4) and the second latent image (5) in the visible image (3), the visible image (3) is viewed under a visible light source, but different predetermined viewing conditions. Below, it becomes possible to visually recognize a different pattern for each predetermined viewing condition. The transmission latent image region (2) of the present invention shown in FIG. 19 (a) has the structure shown in FIG. 19 (b), respectively, according to the first observation condition, the second observation condition, and the third observation condition. Different patterns can be visually recognized.

  When the transmission latent image region (2) shown in FIG. 19 (a) is observed under the first observation condition, the visible image (3) can be visually recognized as shown in FIG. 19 (c1). Is possible. Further, when the so-called transmission latent image region (2) shown in FIG. 19 (a) through the substrate (7) with respect to the visible light source is observed under the second observation condition, FIG. 19 (c3) As shown in FIG. 5, it is possible to visually recognize an image composed of characters, a face image, and the like as the first latent image (4). Furthermore, when observing under the third observation condition using an appraisal device such as an infrared camera, as shown in FIG. 19 (c2), the second latent image (5) is composed of characters, face images, and the like. It is possible to visually recognize the displayed image. As described above, the visible image (3) shown in FIG. 19A has three different patterns. The visual recognition principle will be described later.

  FIG. 19B is a schematic diagram showing a first aspect of the second embodiment. As shown in FIG. 19 (b), the visible image (3) is formed on the concealment layer (8) formed on the substrate (7) by the first halftone dot (14) and the second halftone dot ( 15) and the third halftone dot (16).

  The first halftone dot (14) is a halftone dot that forms a visible image (7) that is visible under reflected light under a visible light source. A plurality of the first halftone dots (14) are arranged, and a continuous tone visible image (3) can be formed according to the size of the halftone dots. In the first halftone dot (14), the third halftone dot (16) is arranged so as to overlap. Further, the second halftone dot (15) is arranged so as to overlap with the third halftone dot (16). In addition, the arrangement | positioning location of the 1st halftone dot (14) in the visible image (3), the 2nd halftone dot (15), and the 3rd halftone dot (16) is not limited to this.

  The size of each halftone dot varies within a predetermined range as described with reference to FIG. 7 in the first embodiment. Since the details of each are the same as those in the first embodiment, description thereof is omitted here.

  FIG. 19C1 is a diagram illustrating an example of the visible image (3) and the first halftone dot (14). A plurality of first halftone dots (14) are arranged to form a visible image (3) that is visible under the first observation condition. The visible image (3) is partially different in size within a predetermined range at the first halftone dot (14), thereby forming an image of Gothic “NPB” and its background. . When the first halftone dot (14) is formed using a colored coloring material that does not contain an infrared absorbing dye, and is observed using a special appraisal device such as an infrared camera, the visible image (3) Cannot be seen.

  In addition, it does not specifically limit in the color material which does not contain an infrared absorption pigment | dye, if it does not have an infrared absorption characteristic, Well-known gravure ink, screen ink, process ink, etc. can be used. For example, among the basic four-color inks, cyan (C), magenta (M), and yellow (Y) have the property of not absorbing infrared rays, and if these three colors are superimposed, a black system can be expressed. The same effect as a color material that does not absorb infrared rays can be obtained. In addition, as black ink that does not absorb infrared rays, ink using chromofine black (manufactured by Dainichi Seika Kogyo Co., Ltd.) or dye-based ink for inkjet printers (for example, dye-based black ink manufactured by Canon, etc.) may be used. it can.

  In the second embodiment, the third halftone dot (16) is configured in the first halftone dot (14), and the second halftone dot (15) is further provided in the third halftone dot (16). It is configured. The first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) are visually recognized in the same color under the first observation condition, so that the first halftone dot (14 ) Only visible. Thereby, only the visible image (3) consisting of the first halftone dot (14) is visible under the first viewing condition.

  In the present invention, the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) have a halftone dot diameter that cannot be visually recognized by distinguishing each region. It is constituted by. Therefore, if the color difference ΔE is less than 6 as described above, the third halftone dot (16) cannot be visually recognized by the naked eye under the reflected light under the visible light source, and the first halftone dot (14), the second halftone dot (15) and the third halftone dot (16) are visually recognized as the same color.

  FIG. 19 (c2) is a diagram illustrating an example of a third halftone dot (16) that forms the second latent image (5). The third halftone dot (16) is an area for forming the second latent image (5) visible in the third viewing condition shown in FIG. 19 (c2). The third halftone dot (16) is arranged so as to overlap with the first halftone dot (14). The second latent image (5) is formed by arranging a plurality of third halftone dots (16). It should be noted that the third halftone dot (16) is also partially different in size within a predetermined range, thereby forming the “house” pattern and the background image.

  FIG. 19B shows a state in which the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) described above are overprinted on the print medium (1). It is a thing. The third halftone dot (16) is placed so as to overlap within the first halftone dot (14). The third halftone dot (16) is made smaller than a certain halftone dot diameter set in the first halftone dot (14). The fixed halftone dot diameter is the minimum size among the plurality of first halftone dots (14) arranged, and the third halftone dot (16) is the first halftone dot (14). Form in a range not exceeding the minimum size.

  The third halftone dot (16) is the same color as the first halftone dot (14) and the second halftone dot (15) in the reflected light, and is formed using a color material containing an infrared absorbing dye. Accordingly, the third halftone dot (16) cannot be visually recognized under the first observation condition, and the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) is visually recognized as the same color.

  As a coloring material containing an infrared absorbing pigment, for example, there is black (Bk) ink mainly composed of carbon black, but as a material for forming the third halftone dot (16) in the present invention, light in the infrared region is used. If it is a color material (especially ink) to absorb, it will not be limited to this. Examples of organic dyes having absorption in the infrared region include polymethylene, phthalocyanine, azo, and anthraquinone compounds, and examples of inorganic infrared absorbers include antimony-doped tin oxide and tin-doped indium oxide. It is done.

  Next, the second halftone dot (15) will be described. The second halftone dot (15) is a halftone dot that forms the first latent image (4) that can be visually recognized under the second observation condition. A continuous tone first latent image (4) can be formed by the size of the second halftone dot (15).

  The second halftone dot (15) is placed so as to overlap within the third halftone dot (16). The second halftone dot (15) is made smaller than a certain halftone dot diameter set in the third halftone dot (16). The constant halftone dot diameter is the minimum size of the plurality of third halftone dots (16), and the second halftone dot (15) is the size of the third halftone dot (16). Form in a range not exceeding the minimum size.

  Since the size of the second halftone dot (15) is the same as the limit of the size of the third halftone dot (16) described above, details are omitted, but the visible image (3) In order not to affect the second latent image (5), it is formed in a range not exceeding the minimum size of the third halftone dot (16).

  Therefore, the relationship between the sizes of the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) is the minimum diameter of the first halftone dot (14) ≧ third. The maximum diameter of the halftone dot (16), the minimum diameter of the third halftone dot (16) ≧ the maximum diameter of the second halftone dot (15).

  FIG. 19 (c3) is a diagram illustrating an example of the second halftone dot (15) that forms the first latent image (4). The second halftone dot (15) is an area for forming the first latent image (4) that can be seen by observing under the second observation condition shown in FIG. 19 (c3). The second halftone dot (15) is arranged so as to overlap with the third halftone dot (16). The first latent image (4) is formed by arranging a plurality of second halftone dots (15). In the second halftone dot (15), the three characters “NPB” in the Mincho style and the background image are formed by partially varying the size within a predetermined range.

  Note that the second halftone dot (15) is not printed on the third halftone dot (16), and the second halftone dot (15) is cut out at the so-called third halftone dot (16). State. By doing so, the second halftone dot (15) in the actual print medium (1) can pass through the cutout area (10) where the concealing material is not printed and the second element (15) through the substrate ( 7) can be confirmed, and as a result, the second halftone dot (15) is formed of the permeable material (6).

  FIG. 20 shows the configuration. As shown in FIG. 20A, when the halftone dot configuration is confirmed from above, it is the same halftone dot configuration as that of the above-described embodiment, and the third halftone dot is within the first halftone dot (14). (16) is arranged, and the second halftone dot (15) is arranged in the third halftone dot (16). As shown in FIG. 20 (b), a concealing layer (8) made of a concealing material is formed on a transparent substrate (7), and an image forming layer (for example, printing ink) is formed on the concealing layer (8). 9) is formed. However, it is preferable to use a coloring material containing an infrared absorbing dye for the transmissive substrate (7), and a specific description thereof will be described later. For the second halftone dot (15), neither the color material containing the infrared absorbing dye nor the color material not containing the infrared absorbing dye is disposed, and there is no color material (for example, printing ink). Yes. The second halftone dot (15) having no coloring material (for example, printing ink) and the cutout region (10) where the concealing material is not applied in the concealing layer (8) are arranged at the same position. .

  In FIG. 20B, FIG. 20C shows a cross-sectional view at X1-X2. As shown in FIG. 20B, the second halftone dot (15) is not printed on the image forming layer (9), and at the same time, a part of the second hiding layer (8) is also hidden. It is a hollow region (10) where no material is applied. The cutout area (10) to which no concealing material is applied has the same size and the same shape as the second halftone dot (15).

  The reason why the transparent material containing the infrared absorbing dye is used for the base material (7) is that the visibility of the second latent image (5) is not affected. When the transparent material (6) containing no infrared absorbing dye is used, it is formed by partially exposing the transparent material as the base material (7) when the print medium is observed under the third observation condition. The second halftone dot (15) is observed to have a low density (whiter). On the other hand, the third halftone dot (16) formed using the color material containing the infrared absorbing dye is observed to have a high density (blackish). Therefore, when the second latent image (5) is observed under the third observation condition, the second halftone dot (15) affects the visibility of the second latent image (5). is there.

  The reason why the concealing material is printed on the transparent base material (7) is that it does not affect the visibility of the visible image (3), and thus has a role of concealing the transparency. .

  Moreover, the reason for using the concealment material that does not contain the infrared absorbing dye is that it does not affect the visibility of the second latent image (5). When a concealing material containing an infrared absorbing dye is used, the first halftone dot (14), the second halftone dot (15), and the third halftone dot when the print medium is observed under the third observation condition. In (16), all of the concentrations are observed to be high (blackish). Therefore, the third halftone dot (16) cannot be distinguished from other halftone dots, and as a result, the second latent image (5) that can be observed under the third observation condition can be visually recognized. become unable.

  Furthermore, the concealing layer (8) formed of the concealing material preferably has a transmittance in the infrared region lower than 80%. When the transmittance of the concealing layer (8) in the infrared region is 80% or more, the concealing layer (8) that conceals the substrate (7) when the print medium is observed under the third observation condition. The first halftone dot (14) is transmitted and the substrate (7) is observed. Therefore, when the base material (7) contains an infrared absorbing pigment, the concentration is observed to be high (blackish). Therefore, the third halftone dot (16) cannot be distinguished from other halftone dots, and as a result, the second latent image (5) that can be observed under the third observation condition can be visually recognized. Therefore, it is not preferable to set the transmittance of the concealing layer (8) in the infrared region to 80% or more.

  FIG. 21 is a graph showing an example of the spectral transmittance of white ink and magenta ink according to the present invention. FIG. 21 (a) shows the spectral transmittance of the concealment material according to the present invention, using a white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample, and colorless (transparent) infrared absorbing dye by inkjet printing. A PET film that did not contain a solid film was used. FIG. 21B is a spectral transmittance of the concealment material in the present invention. Using white ink (LIOJET FV03 White manufactured by Toyo Ink Mfg. Co., Ltd.) as a measurement sample, FIG. The sample shown in (2) was printed at a lower print density.

  FIG. 21 (c) shows the spectral transmittance of the color 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, and PET film by inkjet printing. A solid-printed one was used. The spectral transmittance shown in FIG. 21 shows the spectral transmittance of each measurement sample divided by the spectral transmittance of a colorless (transparent) PET film as a base material. , And measured using a self-recording spectrophotometer (U-4000 model made by HITACHI).

  Comparing changes in spectral transmittance in the infrared region of 760 to 800 nm, the spectral transmittance of the concealment material (a) is almost constant at about 50% in any region. The spectral transmittance of the concealment material (b) printed at a lower print density is about 80% in the infrared region, and is therefore higher than that of the solid concealment material (a) printed. Infrared transmitting colorant (c) containing no infrared absorbing dye is about 95% in the infrared region, so it is compared with solid white ink (a) and white ink (b) printed with a reduced printing density. The value is high. At the same wavelength, in the case of a color material that does not contain an infrared absorbing dye, a lower spectral transmittance is visually recognized as a higher density (whiter), and conversely, a higher spectral transmittance has a lower density (transparent). It is visible. When observing using an infrared camera, the concealment material (a) is observed in white, and the concealment material (b) printed at a lower print density is observed as pale white, and the infrared transmission color material (c ) Was observed almost transparently.

  FIG. 22 is a graph showing an example of the spectral reflectance of the base material (7) according to the present invention, the hiding material forming the hiding layer (8), the ink not containing the infrared absorbing dye, and the ink containing the infrared absorbing dye. . (A) in FIG. 22 is the spectral reflectance of the substrate (7) in the present invention, and a colorless (transparent) PET film having a thickness of 0.2 mm not containing an infrared absorbing dye is used as a measurement sample. It was. (B) is the spectral reflectance of the concealing layer (8) in the present invention, using a white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample, and solidifying the PET film by inkjet printing. A printed one was used. (C) is the spectral reflectance of the coloring material that does not contain the infrared absorbing dye in the present invention, and is solid on a PET film by inkjet printing using magenta ink (LIOJET FV03 Magenta manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample. A printed one was used. (D) is the spectral reflectance of the coloring material containing the infrared absorbing pigment in the present invention, and solid printing is performed on a PET film by inkjet printing using black ink (LIOJET FV03 Black, manufactured by Toyo Ink Manufacturing Co., Ltd.) as a measurement sample. The thing which gave is used.

  In addition, the spectral reflectance shown in FIG. 22 was measured using a self-recording spectrophotometer (U-4000 type manufactured by HITACHI).

  Comparing changes in spectral reflectance in the visible light region of 400 to 760 nm and the infrared region of 760 to 800 nm, the spectral reflectance in the PET film (a) is almost constant at around 95% in any region. is there. The spectral reflectance of the white ink (b) is substantially the same as that of the PET film (a) in any region from the visible light region to the infrared region except for the short wavelength in the visible light region. The spectral reflectance of magenta ink (c) is substantially constant at around 95% in the infrared region. The spectral reflectance in the black ink (d) is substantially constant at around 5% in the infrared 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 using an infrared camera, the PET film (a) and the magenta ink (c) are observed whitish (substantially transparent), the white ink (b) is observed white, and the black ink (d) Was observed black.

  In the case of observation under the third observation condition, the third halftone dot (16) is visually recognized as having a high density (blackish). Similarly, since the base material (7) is a transmissive material containing an infrared absorbing dye, the second halftone dot (15) is visually recognized as having a high density (blackish). That is, in the infrared region, since the second halftone dot (15) and the third halftone dot (16) cannot be identified, the first latent image (4) cannot be visually recognized. In the second latent image (5), an image line having a uniform density is visually recognized as an image formed as a group of image lines.

  The first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) can be formed on the print medium (1) by superposition or tweezers. In the invention, it is preferably formed by superposition. When forming by tapping, high printing accuracy is required. When the printing accuracy is low, a printed portion is generated around each halftone dot. Thereby, in the first viewing condition, the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) do not become the same color, and the first latent image. There is a possibility that the image (4) and the second latent image (5) are visible.

  Furthermore, in the case of observing under the third observation condition, the above-described printed portion transmits infrared rays. Accordingly, since the density of the printed portion is visually recognized as low, the second halftone dot (15) and the third halftone dot (16) in the infrared region do not become a solid region having a uniform density. There is a possibility that the first latent image (4) can be observed.

(Visual image viewing principle)
FIG. 23 is a plan view and a schematic view when the transmission latent image region (2) of the print medium (1) according to the present invention is visually recognized under the first observation condition. In the transmission latent image region (2) shown in FIG. 23 (a1), as shown in FIG. 23 (a2), the first halftone dot (14) is visible under the first observation condition. That is, the visible image (3) can be visually recognized. The first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) cannot be distinguished by being visually recognized in the same color under the first observation condition. The first latent image (4) formed by the second halftone dot (15) and the second latent image (5) formed by the third halftone dot (16) cannot be visually recognized.

  FIG. 23B is a schematic diagram when the print medium (1) is visually recognized under the first observation condition. The principle of visual recognition of the visible image (3) under the first observation condition will be described with reference to FIG. When viewed with the naked eye under the first observation condition, first, the specularly reflected light and the diffused light (R2) are incident on the first halftone dot (14) by the incident light (R1) from the visible light source (R). ) Occurs, and diffused light (R2) is obtained as reflected light.

  For the second halftone dot (15), incident light (R1) from the visible light source (R) generates specularly reflected light and diffused light (R3), and diffused light (R3) is obtained from the reflected light. It is done. At the third halftone dot (16), the incident light (R1) from the visible light source (R) generates specularly reflected light and diffused light (R2), and the reflected light obtains diffused light (R2). It is done. Since the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) are formed so as to have the same color when observed under the first observation condition, The difference in reflected light in each region cannot be confirmed.

  In the second embodiment, the third halftone dot (16) is arranged so as to overlap within the first halftone dot (14), and the second halftone dot (16) is further placed within the third halftone dot (16). 15) are superimposed. The maximum halftone dot diameter and the minimum halftone dot diameter at the first halftone dot (14), the maximum halftone dot diameter and the minimum halftone dot diameter at the second halftone dot (15), and the maximum halftone dot at the third halftone dot (16). The relationship between the diameter and the minimum halftone dot size is that the minimum halftone dot diameter of the first halftone dot (14) ≧ the maximum halftone dot diameter of the third halftone dot (16) and the minimum halftone dot of the third halftone dot (16). The maximum halftone dot diameter of the dot diameter ≧ second halftone dot (15) is satisfied.

  Under the first observation condition, the reflected light intensity of the visible image (3), the first latent image (4), and the second latent image (5) is substantially constant. Therefore, the third halftone dot (16) is arranged so as to overlap within the first halftone dot (14), and the second halftone dot (15) is arranged so as to overlap within the third halftone dot (16). The first halftone dot (14) is made larger in diameter than the second halftone dot (15) and the third halftone dot (16), so that the first latent image (4). And the second latent image (5) is hidden in the visible image (3). Therefore, when the print medium (1) is observed under the first observation condition, only the visible image (3) constituted by the first halftone dot (14) can be visually recognized, and the second halftone dot ( The first latent image (4) constituted by 15) and the second latent image (5) constituted by the third halftone dot (16) cannot be visually recognized.

(First latent image image viewing principle)
FIG. 24 is a plan view and a schematic view when the transmission latent image region (2) of the print medium (1) is visually recognized under the second observation condition. In the transmission latent image region (2) shown in FIG. 24 (a1), the second halftone dot (15) is visible under the second observation condition shown in FIG. 24 (b). That is, the first latent image (4) can be visually recognized. The second halftone dot (15) can be distinguished from the second halftone dot (15) and the third halftone dot (16) by visually recognizing the color difference ΔE changing under the second observation condition. The first latent image (4) formed by the second halftone dot (15) can be visually recognized.

  The visual recognition principle of the first latent image (4) under the second observation condition will be described with reference to FIG. When the print medium (1) is visually recognized under the second observation condition, first, the transmitted light is transmitted to the first halftone dot (14) by the incident light (R1) from the visible light source (R). (R4) is obtained. Further, in the second halftone dot (15) forming the first latent image (4), the transmitted light (R5) is obtained by the incident light (R1) from the visible light source (R). At the third halftone dot (16) forming the second latent image (5), the transmitted light (R4) is obtained by the incident light (R1) from the visible light source (R).

  Therefore, the second halftone dot (15) is formed of the transmissive material (6), and the transmitted light (R5) of the second halftone dot (15) is the first halftone dot (14) and the second halftone dot (14). And the second halftone dot (16) with respect to the first halftone dot (14) and the third halftone dot (16) due to the difference in brightness. Since a color difference ΔE that can identify 15) occurs, the first latent image (4) can be visually recognized as a latent image. Therefore, under the second observation condition, when the print medium (1) is observed, a new first latent image (4) can be visually recognized.

  In the second observation condition, the first halftone dot is determined by the difference in the intensity of the incident light (R1) from the visible light source (R), the transmittance of the base material (7), or the transmittance of the ink in each region. In some cases, a difference occurs in the transmitted light (R4) of each of (14) and the third halftone dot (16), and the color difference ΔE between the first halftone dot (14) and the third halftone dot (16) changes. is there.

  However, since the second halftone dot (15) is formed using the transparent material (6), the change in the color difference ΔE between the first halftone dot (14) and the third halftone dot (16). The amount is smaller than the amount of change in the color difference ΔE between the second halftone dot (15), the first halftone dot (14), and the third halftone dot (16). Therefore, it becomes impossible to distinguish the first halftone dot (14) and the third halftone dot (16) due to the visual masking effect. That is, the second latent image (5) cannot be visually recognized. Therefore, when the transmitted latent image region (2) is visually recognized with the naked eye in the transmitted light under the visible light source (R), the first latent image (4) can be newly visually recognized.

  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. As a result, masking phenomenon (only a large stimulus can be seen) occurs in which a small stimulus cannot be seen. Depending on the setting of the halftone dot diameter of the second halftone dot (15) and the selection of the transparent material forming the second halftone dot (15), the first halftone dot (14) and the third halftone dot (15) may be used. The amount of change in the color difference ΔE at the point (16) approximates the amount of change in the color difference ΔE between the second halftone dot (15) and the third halftone dot (16), and the visual masking effect is weakened. The visibility of the image image (4) may be reduced.

  Therefore, the amount of change in the color difference ΔE between the second halftone dot (15) and the third halftone dot (16) is the change in the color difference ΔE between the first halftone dot (14) and the third halftone dot (16). It is preferable to set the halftone dot diameter of the second halftone dot (15) so as to be larger than the amount, or to appropriately select the permeable material (6) forming the second halftone dot (15). .

(The principle of visual recognition of the second latent image pattern)
FIG. 25 is a plan view and a schematic view when the transmission latent image region (2) of the print medium (1) according to the present invention is observed under the third observation condition. The principle that the second latent image (5) can be observed under the third viewing condition will be described with reference to FIG. When the transmission latent image region (2) of the print medium (1) is observed under the third observation condition, as shown in FIG. 25 (a2), the first halftone dot (14) is a color that does not contain an infrared absorbing dye. Since it is made of a material, it is observed as white.

  As described above, the third halftone dot (16) is formed using a color material containing an infrared absorbing pigment, and thus has a low spectral reflectance in the infrared region, and thus has a high density and is observed as dark. Moreover, in the 1st aspect of 2nd Embodiment, the 2nd halftone dot (15) is permeable material (7) which is a base material (7) through the hollow area (10) which does not give a concealment material. 6) partly exposed, and since the base material (7) is a transparent material (6) containing an infrared absorbing dye, it is the same color as the third halftone dot (16) in the reflected light. By setting to, the second halftone dot (15) and the third halftone dot (16) are observed at the same density when observed under the third observation condition. Therefore, the second latent image (5) can be newly observed in the infrared region.

(Second aspect of the second embodiment)
Next, another embodiment of the present invention will be described. In the 1st aspect of 2nd Embodiment, although the transparent material (6) containing an infrared rays absorption pigment | dye was used for the base material (7) about the base material (7) which is a 1st layer, 2nd In the second aspect of the embodiment, both the transparent material (6) containing an infrared absorbing dye and the transparent material (6) containing no infrared absorbing dye can be used for the substrate (7). A specific description of each case will be described later. A part of the concealing layer (8) that is the second layer and the image forming layer (9) that is the third layer overlaps with the first aspect of the second embodiment. Will be omitted.

  The second aspect of the second embodiment differs from the first aspect of the second embodiment in that the concealed layer (8) and the image forming layer (9) are hollowed out in the respective layers. The latent image is formed by the difference in the concealed area ratio and the transmittance.

  First, the layer structure in the concealment layer (8) will be described with reference to FIG. Since the concealing layer (8) plays the role of concealing the transparency of the base material (7) as in the first aspect of the second embodiment, it is formed using white ink. However, although white ink is printed also on the portion corresponding to the cutout region (10) in the first aspect of the second embodiment, it is formed with a hidden area ratio lower than the surrounding hidden area ratio. As in the second aspect of the first embodiment, this area is defined as a second concealment area (12).

  Therefore, the relationship between the first concealment area ratio of the first concealment region (11) and the second concealment area ratio of the second concealment region (12) constituting the concealment layer (8) is as follows. Hiding area ratio> second hiding area ratio. However, since it is necessary for the second concealment region (12) to be accompanied by the transparency of the base material (7) in the lower layer in the transmitted light, the second concealment area ratio is in the range of 0% or more and less than 100%. It is necessary to.

  Moreover, since it is necessary for the 1st concealment area | region (11) to suppress the transmittance | permeability of the base material (7) of a lower layer in the transmitted light, about 1st concealment area ratio is larger than 0% and 100% or less. It is necessary to be in the range. As described above, the second concealment region (12) is defined as being separated from the cutout region (10) in the first aspect of the second embodiment by printing white ink. The second concealment area ratio of the second concealment region (12) may be 0%. For example, as in the first aspect of the second embodiment, the first concealment area ratio of the first concealment region (11) is 100%, and the second concealment area of the second concealment region (12). The rate may be 0%.

  By making the second concealment region (12) have a concealment area ratio lower than that of the first concealment region (11), the transparency in the base material (7) can be visually recognized in the transmitted light as described above. Therefore, the first latent image (4) is formed by arranging a plurality of second concealment regions (12). Even if the first hidden area ratio and the second hidden area ratio are set to be approximately 0% or 0%, that is, a setting in which the hidden layer (8) is substantially omitted, the second hidden area as a printed matter. If the transparency of (12) is higher than the first halftone dot (14), the first latent image (4) in the transmitted light is visible. However, if the first hidden area ratio and the second hidden area ratio are approximated, the visibility of the first latent image (4) in the transmitted light may be reduced. Therefore, the first hidden area ratio and the second hidden area ratio It is necessary to appropriately set the concealment area ratio of 2.

  Next, the image forming layer (9) in the second aspect of the second embodiment will be described. About this image formation layer (9), like the 1st aspect of 2nd Embodiment, the visible image (3) which can be visually recognized on 1st observation conditions is formed, and a visible image is formed. The basic halftone dot configuration for doing this is the same as the first aspect of the second embodiment.

  In the first aspect of the second embodiment, a hollow region formed in the concealment layer (8) in the first halftone dot (14) to form the first latent image (4). Although the second halftone dot (15) is cut out at the same position as (10), in the second aspect, the second element (15) in the first aspect is formed. The portion corresponding to the above is not cut out, and is formed of an ink layer having a high transmittance so that the transparency of the base material (7) as the lowermost layer is accompanied.

  With respect to the second halftone dot (15) in the image forming layer (9), there are two formation methods. First, as the second aspect of the second embodiment, FIG. The second will be described as the third aspect of the second embodiment to be described later.

  As shown in FIG. 27, the image forming layer (9) includes a first halftone dot (14) for forming a visible image (3) and a first dot for forming a first latent image (4). The second halftone dot (15) and the third halftone dot (16) for forming the second latent image (5) are the same as the first aspect of the second embodiment. It is the same. However, as described above, in the third halftone dot (16), the second halftone dot (15) for forming the first latent image (4) is the third halftone dot (16). Cannot be distinguished.

  In FIG. 27A, in order to show the positional relationship between the first latent image region (11) and the second latent image region (13) in the lower layer, the image is shown by an image line in the first halftone dot (14). As shown in the sectional view of FIG. 27B, there is actually a region corresponding to the second halftone dot (15) in the third halftone dot (16). do not do. However, since the area illustrated by the image line is an area for forming the first latent image (4) in the second mode of the second embodiment, The second halftone dot (15) is defined as in the first aspect of the form.

  The second halftone dot (15) is constituted by the third halftone dot (16) in the first aspect of the second embodiment. However, it is necessary to set the transmittance so that the transmittance of the lowermost base material (7) can be visually recognized in the transmitted light through the second concealment region (12) in the concealment layer (8) which is the lower layer. There is. Therefore, the transmittance of the second halftone dot (15) needs to be in the range of 3% to 100%.

  Further, the second halftone dot (15) forms the second halftone dot (15) so that the first latent image (4) cannot be visually recognized under the first observation condition. Thus, in the first observation condition, the substrate (7) and the first concealment region (11) in the concealment layer (8) that are visible through the second concealment region (12) in the concealment layer (8). It is necessary to make the colors of the same color. Therefore, in the first observation condition, the third halftone dot (16) and the second halftone dot (15) are formed so as to have the same color.

  Further, when the lowermost base material (7) is a transparent material (6) containing no infrared absorbing dye, the second halftone dot (15) needs to be formed of a color material containing an infrared absorbing dye, When the lowermost base material (7) is a transparent material (6) containing an infrared absorbing dye, the second halftone dot (15) is not particularly limited. This is because the visibility of the second latent image (5) is not affected. That is, when the lowermost substrate (7) is observed through the second halftone dot (15), that is, the second halftone dot (15) under the third observation condition, the color containing the infrared absorbing dye. This is because the third halftone dot (16) formed of the material is observed at the same concentration.

  FIG. 28 illustrates the layer configuration in the second mode of the second embodiment. As shown in FIG. 28A, when the halftone dot configuration is confirmed from above, the halftone dot configuration is the same as that of the above-described embodiment, and the third halftone dot is included in the first halftone dot (14). (16) is arranged, and the second halftone dot (15) is arranged in the third halftone dot (16). As shown in FIG. 28 (b), the first concealment region (11) of the concealment layer (8) formed on the substrate (7) and the image formation layer (9) of the concealment layer (9) formed further thereon. The first halftone dot (14) and the third halftone dot (16) are arranged at the same position, the third halftone dot (16) is arranged in the first halftone dot (14), and the image forming layer ( The second halftone dot (15) of 9) is arranged within the third halftone dot (16). Similarly, the second concealment area (12) and the second halftone dot (15) are the same. Placed in position. As shown in FIG. 28C, on the second concealment region (12) formed in the concealment layer (8), which is the region for forming the first latent image (4), The second halftone dot (15) in the range of not less than 3% and not more than 100% transmittance formed so that the halftone dot (15) and the third halftone dot (16) have the same color under the first observation condition. Will be placed.

  By adopting the layer configuration shown in FIG. 28, as in the first aspect of the second embodiment, the first viewing condition allows the first halftone dot (14) of the image forming layer (9). The formed visible image (3) is visually recognized. Then, when the print medium (1) is observed under the second observation condition, the second concealment region (12) having a concealment area ratio lower than that of the first concealment region (11) via the image forming layer (9). ) Can be further confirmed through the substrate (7). Therefore, the region in the image forming layer (9) where the substrate (7) can be confirmed through the second concealment region (12) results in the second halftone dot (15). The first latent image (4) formed by arranging a plurality of two halftone dots (15) can be viewed.

(Third aspect of the second embodiment)
Next, as a third aspect of the second embodiment, in addition to the first forming method in the image forming layer (9), the second forming method of the second halftone dot (15). Will be described with reference to FIG. The first halftone dot (14) is the same as the image forming layer (9) of the second aspect of the second embodiment described above, but the second halftone dot (15) It forms in the location applicable to the same position as the 2nd concealment area | region (12) formed in a concealment layer (8). Therefore, the second halftone dot (15) and the third halftone dot (16) are formed by two colors. The second halftone dot (15) is formed in the range of transmittance of 3% to 100%. If it is lower than this range, the transparency of the lowermost substrate (7) cannot be confirmed.

  As described above, the second concealment region (12) formed in the concealment layer (8) has a concealment area ratio so low that the permeability of the base material (7) can be confirmed. By forming the transmittance of the halftone dot (15) high, the transparency of the lowermost base material (7) can be confirmed in the transmitted light through the second concealment region (12) as the lower layer. Become. However, in order to make the first latent image (4) invisible in the reflected light, the second halftone dot (15) and the third halftone dot (16) are formed to have the same color. To do.

  Further, when the lowermost base material (7) is a transparent material (6) containing no infrared absorbing dye, the second halftone dot (15) needs to be formed of a color material containing an infrared absorbing dye, When the lowermost base material (7) is a transparent material (6) containing an infrared absorbing dye, the second halftone dot (15) is not particularly limited.

  FIG. 30 illustrates the layer configuration of the third aspect in the second embodiment. As shown in FIG. 30A, when the halftone dot configuration is confirmed from above, the halftone dot configuration is the same as that of the above-described embodiment, and the third halftone dot is included in the first halftone dot (14). (16) is arranged, and the second halftone dot (15) is arranged in the third halftone dot (16). As shown in FIGS. 30B and 30C, the first concealment region (11) of the concealment layer (8) formed on the substrate (7) and the image forming layer (11) formed thereon ( 9) the first halftone dot (14) and the third halftone dot (16) are arranged at the same position, and the third halftone dot (16) is arranged within the first halftone dot (14); Further, the second halftone dot (15) is arranged in the third halftone dot (16), and the second concealment region (12) and the second halftone dot (15) are arranged at the same position. In addition, as shown in FIG.30 (c), on the 2nd concealment area | region (12) formed in the concealment layer (8) used as the area | region which forms 1st latent image (4), it is transparent. A second halftone dot (15) with a rate ranging from 3% to 100% is arranged, and the second halftone dot (15) and the third halftone dot (16) are the same color under the first observation condition. Thus, it is formed by two colors.

  With the layer configuration shown in FIG. 30, as in the first aspect and the second aspect in the second embodiment, under the first observation condition, the first image forming layer (9) The visible image (3) formed by the halftone dots (14) is visually recognized. Then, when the print medium (1) is observed under the second observation condition, the second concealment region having a concealment area ratio lower than that of the first concealment region (11) through the second halftone dot (15). The substrate (7) can be confirmed through (12). Therefore, it is possible to visually recognize the first latent image (4) formed by arranging a plurality of the second halftone dots (15).

  Note that the third aspect of the second embodiment is characterized in that a hollow region is not formed in each of the concealing layer (8) and the image forming layer (9). Either the second hidden area (12) or the second halftone dot (15) in the image forming layer (9) may be formed as a hollow area.

  In the first embodiment, the visible image can be visually recognized when observed under the first observation condition, and the first latent image can be visually recognized by observing the print medium under the second observation condition. The medium could be made. In the first embodiment, it is also possible to change only the transmissive material (6) forming the base material (7) or to change the color material forming the second halftone dot (15). Thus, it is possible to form two images with different viewing conditions on one print medium. For example, the visible image (3) can be visually recognized when observed under the first observation condition, and the first latent image (4) is visually recognized by observing the printed matter under the second observation condition. In addition, the first latent image appears again when the image is observed using an identification device such as an infrared camera. This will be described below.

  In the first aspect, the second aspect, or the third aspect of the first embodiment, the first halftone dot (14) is formed using ink that does not contain an infrared absorbing dye. Moreover, the base material (7) is formed of a transparent material (6) containing an infrared absorbing dye or the second halftone dot (15) by a color material (for example, printing ink) containing an infrared absorbing dye. Thus, the second halftone dot (15) forms a first latent image (4) that can be observed under two different observation conditions, the second observation condition and the third observation condition. . This makes it impossible to distinguish the first halftone dot (14) and the second halftone dot (15) because they are visually recognized as the same color in the first observation condition. The first latent image (4) formed in 15) cannot be visually recognized.

  In the second observation condition, the second halftone dot (15) is visible. That is, the first latent image (4) can be visually recognized. This makes it possible to distinguish the first halftone dot (14) and the second halftone dot (15) by visually recognizing the color difference ΔE changing under the second observation condition. The first latent image (4) formed at the point (15) can be visually recognized.

  Furthermore, when observed under the third observation condition, the base material which is a transparent material (6) containing an infrared absorbing dye via the second halftone dot (15) and further via the second concealment region (12) The second halftone dot (15) formed using the ink containing (7) or the infrared absorbing dye becomes observable. As described above, the second halftone dot (15) is disposed within the first halftone dot (14). That is, under the third viewing condition, the first latent image (4) appears again.

  The visible image (3), the first latent image (4), and the second latent image (5) of the present invention are not particularly limited, such as letters, numbers, symbols, patterns, and scenery, and are appropriately selected. It is possible to design. Moreover, although the halftone dot shape in each of the first halftone dot (14), the second halftone dot (15), and the third halftone dot (16) has been described as a circle, it is not limited to a circle. A triangular shape such as a triangle, square, and polygon, a random shape, or a halftone dot shape proposed in Japanese Patent No. 3478474 filed earlier by the present applicant may be used.

  As a color material for forming the first halftone dot (14), the second halftone dot (15) and the third halftone dot (16) constituting the image forming layer (9), a known gravure ink, Colored inks such as screen inks, process inks and inks for inkjet printers can be used. The method of forming each halftone dot is not particularly limited, such as an offset printing method, a gravure printing method, a screen printing method, a flexographic printing method, an ink jet printer, and a laser printer.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

  As Example 1, as shown in FIG. 1, a card-type certificate (1) in which a transmission latent image region (2) according to the present invention was formed in the lower left part was produced. When this certificate (1) is observed under the first viewing condition, the transmission latent image region (2) can confirm the Gothic “NPB” shown in FIG. ) Under the second observation condition, the transmission latent image region (2) can confirm the three characters “NPB” of the Mincho style shown in FIG. 2B.

  As the base material (7) of the certificate (1) in Example 1, a colorless (transparent) PET film having a thickness of 0.2 mm was used. Therefore, in Example 1, the permeable material (6) was used on the entire surface of the base material, that is, the base material itself.

  Next, except for the transmission latent image region (2) on the base material (7), solid printing was performed using white ink (LIOJET FV03 white manufactured by Toyo Ink Manufacturing Co., Ltd.), and the transmission latent image region (2) was the same. Using the white ink, the first concealed area (11) for suppressing the permeability of the PET film of the base material (7) and the area where the white ink is not printed ("cutout area (10)" in the above-described embodiment) ) To form a concealing layer (8).

  The first concealment region (11) was printed with a concealment area ratio of 100% (solid). Further, the cutout region (10) where the white ink is not printed is at the same position as the second halftone dot (15) of the image forming layer (9) printed on the white ink. .

  Next, an image forming layer (9) was formed on the entire surface of the concealing layer (8) formed with white ink using process ink (LIOJET FV03 cyan, magenta, yellow, black, manufactured by Toyo Ink Manufacturing Co., Ltd.). . With respect to the image forming layer (9), normal printing using halftone dots other than the transmission latent image region (2) is performed, and the transmission latent image region (2) is the first embodiment as shown in FIG. The pattern shown in FIG. 6A was formed by the halftone dot configuration.

  The halftone dots in the transmission latent image region (2) of the image forming layer (9) are the same with 45 lines, and the halftone dot diameter is 300 μm at the maximum diameter of the first halftone dot (14). The minimum diameter was 190 μm, and the second halftone dot (15) had a maximum diameter not exceeding the minimum diameter of the first halftone dot (14), and the minimum diameter was 0 μm.

  The image forming layer (9) was formed according to the third aspect of the first embodiment shown in FIG. The first halftone dot (14) was printed in black by overlaying process ink (LIOJET FV03 cyan, magenta, yellow, manufactured by Toyo Ink Manufacturing Co., Ltd.). In accordance with the gradation of the “NPB” of the Gothic type shown in FIG. 2A, the halftone dot diameter of the first halftone dot (14) is changed within a range of a maximum diameter of 300 μm and a minimum diameter of 190 μm, and a visible image ( 3) was formed.

  Next, as described above, the second halftone dot (15) is located at the same position as the cutout area (10) where the white ink of the concealing layer (8) is not printed. Accordingly, since the second halftone dot (15) of the image forming layer (9) and the hollowed area (10) of the concealing layer (8) are at the same position, the second halftone dot (15 ) Through which the PET film of the substrate (7) can be confirmed.

  In order not to make the first latent image (4) formed by the second halftone dot (15) visible in the first observation condition, the second halftone dot (15) Printing was performed using process ink (LIOJET FV03 Black manufactured by Toyo Ink Manufacturing Co., Ltd.) so as to be the same color as the first halftone dot (14). In accordance with the gradation of “NPB” of the Gothic body shown in FIG. 2B, the halftone dot diameter of the second halftone dot (15) is changed within the range of the maximum diameter of 190 μm and the minimum diameter of 0 μm. A latent image (4) was formed. The color difference ΔE between the first halftone dot (14) and the second halftone dot (15) in the reflected light was 0.85.

  FIG. 31 schematically shows the configuration of the transmission latent image region (2) in the certificate (1) of Example 1 and the configuration of regions other than the transmission latent image region (2). FIG. 31 (a) shows the configuration of a region other than the transmission latent image region (2), and a white ink is printed on a colorless (transparent) PET film that is a transparent substrate (7). Furthermore, a halftone dot for forming a visible image (3) is printed on it with process ink.

  FIG. 31B shows the configuration of the transmission latent image region (2), and FIG. 31C shows a cross-sectional view at X1-X2. As shown in FIG.31 (b), on the colorless (transparent) PET film which is a transparent base material (7), as a concealment layer (8), the 1st concealment area | region (11) is white ink. Printed, part of which is a cutout area (10) where no concealing material is applied. A first halftone dot (14) is printed on the first concealment area (11) and a second halftone dot (15) is printed on the cutout area (10). The cutout region (10) and the second halftone dot (15) are printed at the same position.

  In addition, when supplementing about the 2nd halftone dot (15) formed on the hollow area | region (10) in the concealment layer (8), in FIG.31 (c), the 2nd halftone dot (on the hollow area | region (10) ( 15) is formed, and the portion corresponding to the cut-out region (10) is formed in a hollow state, but this is merely a schematic representation, and in the actual print medium (1), There are no cavities. As a layer structure of the printing medium, it means that a concealing layer (8) having a cutout region (10) is formed on a substrate (7) and an image forming layer (9) is formed thereon, The second halftone dot (15) constituting the image forming layer (9) is printed at the same position as the cutout region (10) where the hiding layer (8) does not exist.

  By determining the positional relationship between the layer configuration and the halftone dot configuration as described above, the permeability of the base material (7) is confirmed through the hollowed region (10) at the second halftone dot (15) as described above. Is possible. Further, since the transparency of the base material (7) is suppressed by the white ink in the areas other than the cut-out area (10), it is visible by the process ink printed on the white ink without any transparency. An image (3) is formed.

  When the print medium (1) produced in Example 1 was observed under the first observation condition, the Gothic character “NPB”, which is the visible image (3), can be visually recognized. The image image (4) could not be visually recognized. Next, when the print medium (1) produced in Example 1 was observed under the second observation condition, the second halftone dot (15) was visually recognized brightly, and the first latent image (4) was observed. I was able to see the three letters “NPB” in a certain Mincho style.

  When visually recognized under the second observation condition, the transmitted light (R5) of the second halftone dot (15) forming the first latent image (4) is transmitted through the first halftone dot (14) ( Since the color difference ΔE between the second halftone dot (15) and the first halftone dot (14) is greatly changed due to the difference in brightness, the first latent image (4) is visually recognized. It became possible.

  Furthermore, the print medium (1) produced in Example 1 was observed under the third observation condition. The infrared display device used was a CCD camera WAT-704R manufactured by Watec Co., Ltd. and a sharp cut filter IR-80 manufactured by Fuji Photo Film Co., Ltd. was mounted. The visible image (3) cannot be observed, and the first latent image (4) composed of the second halftone dots (15) is displayed dark (blackish), and again the first latent image is displayed. The image (4) was clearly visible.

  As Example 2, as shown in FIG. 32, a card-type certificate (1 ') having a transmission latent image region (2') according to the present invention formed in the lower right portion was produced. When this certificate (1 ′) is observed under the first observation condition, the transmission latent image region (2 ′) can confirm the “star” figure shown in FIG. When 1 ′) is confirmed under the second viewing condition, the transmission latent image region (2 ′) can visually recognize the “¥ 1000” characters of Mincho as shown in FIG. When observed under the third observation condition, the “smile” figure shown in FIG. 33B can be confirmed.

  As the base material (7 ') of the certificate (1') in Example 2, a colorless (transparent) PET film having a thickness of 0.2 mm was used. Therefore, in Example 2, the permeable material (6) was used on the entire surface of the base material, that is, the base material itself.

  Next, a solid image is printed on the substrate (7 ′) other than the transmission latent image region (2 ′) using white ink (LIOJET FV03 White manufactured by Toyo Ink Manufacturing Co., Ltd.), and the transmission latent image region (2 ′) is printed. The same white ink is used so that the transparency of the first concealment region (11 ′) and the base material (7 ′) for suppressing the transparency of the PET film of the base material (7 ′) is visible. The concealment layer (8 ′) was formed so as to have the second concealment region (12 ′) having a concealment area ratio.

  The first hidden area (11 ′) was printed with a first hidden area ratio of 100% (solid), and the second hidden area (12 ′) was printed with a second hidden area ratio of 10%. . The second concealment region (12 ') is at the same position as the second halftone dot (15') of the image forming layer (9 ') printed on the white ink.

  Next, an image forming layer (9 ′) is formed on the entire surface of the concealing layer (8 ′) formed with white ink using process ink (LIOJET FV03 cyan, magenta, yellow, black, manufactured by Toyo Ink Manufacturing Co., Ltd.). Formed. For this image forming layer (9 ′), normal printing is performed with halftone dots except for the transmission latent image region (2 ′), and the transmission latent image region (2 ′) is as shown in FIG. The pattern of FIG. 33A was formed by the halftone dot configuration in the second embodiment.

  The halftone dots in the transmission latent image region (2 ′) of the image forming layer (9 ′) are the same in 45 lines, and the halftone dot diameter is the maximum diameter of the first halftone dot (14 ′). Is 350 μm, the minimum diameter is 300 μm, the third halftone dot (16 ′) has a maximum diameter not exceeding the minimum diameter of the first halftone dot (14 ′), the minimum diameter is 190 μm, The halftone dot (15 ′) has a maximum diameter that does not exceed the minimum diameter of the third halftone dot (16 ′), and the minimum diameter is 0 μm.

  The image forming layer (9 ') was formed according to the third aspect of the second embodiment shown in FIG. The first halftone dot (14 ') was printed in black by overlaying process ink (LIOJET FV03 cyan, magenta, yellow, manufactured by Toyo Ink Manufacturing Co., Ltd.). In accordance with the gradation of the “star” figure shown in FIG. 33 (a), the halftone dot diameter of the first halftone dot (14 ′) is changed within the range of the maximum diameter of 350 μm and the minimum diameter of 300 μm. 3 ′) was formed.

  Next, a third halftone dot (16 ') was formed in the first halftone dot (14'). In order not to make the second latent image (5 ′) formed by the third halftone dot (16 ′) visible in the first observation condition, the third halftone dot (16 ′) Printing was performed using process ink (LIOJET FV03 Black, manufactured by Toyo Ink Manufacturing Co., Ltd.) so as to be the same color as the first halftone dot (14 ′) under the observation conditions. In accordance with the gradation of the “smile” figure shown in FIG. 33B, the halftone dot diameter of the third halftone dot (16 ′) is changed within the range of the maximum diameter of 300 μm and the minimum diameter of 190 μm. A latent image (5 ′) was formed. The color difference ΔE between the first halftone dot (14 ') and the third halftone dot (16') in the reflected light was 1.01.

  Next, the second halftone dot (15 ') was formed at the same position as the second concealment region (12') of the concealment layer (8 ') as described above. Therefore, since the second halftone dot (15 ′) of the image forming layer (9 ′) and the second hidden area (12 ′) of the hidden layer (8 ′) are at the same position, the area is The PET film of the substrate (7 ′) can be confirmed through the second halftone dot (15 ′) and further through the second concealed region (12 ′) of the layer below it. Yes.

  In order not to make the first latent image (4 ′) formed by the second halftone dot (15 ′) visible in the first observation condition, the second halftone dot (15 ′) It printed using process ink (LIOJET FV03 black by Toyo Ink Manufacturing Co., Ltd.) so that it may become the same color as the 3rd halftone dot (16 ') on condition. The halftone dot diameter of the second halftone dot (15 ') is changed within the range of the maximum diameter of 190 μm and the minimum diameter of 0 μm in accordance with the gradation of the character “¥ 1000” shown in FIG. The first latent image (4 ′) was formed. The color difference ΔE between the second halftone dot (15 ′) and the third halftone dot (16 ′) in the reflected light was 0.87.

  FIG. 34 schematically shows the configuration of the transmission latent image region (2 ′) in the certificate (1 ′) of Example 2 and the configuration of the region other than the transmission latent image region (2 ′). FIG. 34 (a) shows a halftone dot configuration in a region other than the transmission latent image region (2 ′), and a white ink is formed on a colorless (transparent) PET film that is a transparent substrate (7 ′). Is printed on it, and a halftone dot for forming a visible image (3) is printed on it using process ink.

  FIG. 34 (b) shows the configuration of the transmission latent image region (2 '), and FIG. 34 (c) shows a cross-sectional view at X1-X2. As shown in FIG. 34 (b), on the colorless (transparent) PET film which is the transparent base material (7 ′), the first concealment region (11 ′) and the second concealment region (12 ′ ) Is printed with white ink, a first halftone dot (14 ') is printed on the first concealment region (11'), and a third halftone dot (14 ') is printed within the first halftone dot (14'). A dot (16 ′) was printed, and a second halftone dot (15 ′) was printed on the second hidden area (12 ′). In particular, the second concealment region (12 ') and the second halftone dot (15') are printed at the same position.

  By having such a positional relationship between the layer configuration and the halftone dot configuration, as described above, in the second halftone dot (15 ′), the base material (7 ′) passes through the second concealment region (12 ′). It becomes possible to confirm the permeability. Further, in the areas other than the second concealed area (12 ′), the transparency of the base material (7 ′) is suppressed by the solid printing of the white ink. A visible image (3 ′) is formed by the process ink being printed.

  When the print medium (1 ′) produced in Example 2 was observed under the first observation condition, the visible image (3 ′) of the “star” figure shown in FIG. The first latent image (4 ′) and the second latent image (5 ′) were not visible. Next, when the printing medium (1 ′) produced in Example 2 was observed under the second observation condition, the second halftone dot (15 ′) was visually recognized as bright and shown in FIG. The first latent image (4 ′) with the characters “¥ 1000” could be visually recognized.

  When viewed under the second viewing condition, the transmitted light (R5) of the second halftone dot (15 ′) that forms the first latent image (4 ′) is the first halftone dot (14 ′) and Brighter than the transmitted light (R4) of the third halftone dot (16 ′), and due to the difference in brightness, the color difference ΔE between the second halftone dot (15 ′) and the third halftone dot (16 ′) is large. Since it changed, it became possible to visually recognize the first latent image (4 ′).

  Furthermore, the printing medium (1 ') produced in Example 2 was observed under the third observation condition. As the 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. were used. As a result, the visible image (3 ') could not be observed. Further, the second halftone dot (15 ') was displayed dark (blackish), and the third halftone dot (16') was also darkly (blackish) displayed. Therefore, the second latent image (5 ') having the "smile" figure formed by the third halftone dot (16') as shown in FIG. Note that the second halftone dot (15 ′) is the same color as the third halftone dot (16 ′) under the first observation condition, and a color material containing an infrared absorbing dye is used. Since the second halftone dot (15 ′) and the third halftone dot (16 ′) cannot be identified in the region, the first latent image formed in the second latent image (5 ′). The image (4 ′) could not be visually recognized. As a result, only the second latent image pattern (5 ') could be observed.

1, 1 'print medium having a transmission latent image 2, 2' transmission latent image region 3, 3 'visible image 4, 4' first latent image 5, 5 'second latent image 6, 6' , 6a, 6b, 6b 'Transparent material 7, 7' Base material 8, 8 'Hiding layer 9, 9' Image forming layer 10, 10 'Hollow area 11, 11' First hiding area 12, 12 'Second Hiding area 14, 14 'first halftone dot 15, 15' second halftone dot 16, 16 'third halftone dot R visible light source K infrared light source

Claims (6)

In a substrate made of at least a part of a colorless and / or colored transparent material, a transmission latent image region is formed on a part of the substrate made of the transparent material,
In the transmission latent image region on the substrate, a concealing layer made of a concealing material for suppressing the transparency of the transmissive material is formed,
i) The concealment layer includes a first concealment area composed of a first concealment area ratio provided with a concealment material that conceals the permeability of the base material, and the concealment material for partially exposing the base material. Consisting of a hollow area that has not been subjected to, or
ii) The concealment layer includes a first concealment area composed of a first concealment area ratio provided with a concealment material concealing the permeability of the base material, and a second concealment area ratio lower than the first concealment area ratio. Formed by a second concealment region comprising a concealment area ratio;
An image forming layer is formed by arranging a plurality of first halftone dots and second halftone dots on the concealment layer,
A plurality of the first halftone dots are arranged using a colored color material to form a visible image,
In the case of i), a second halftone dot that is not provided with the colored coloring material is formed in the first halftone dot, and the cutout region and the second halftone dot are arranged at the same position, A first latent image is formed by arranging a plurality of second halftone dots.
In the case of ii), a second halftone dot having a transmittance of 3% or more and 100% or less is formed in the first halftone dot by the colored color material, and the second concealed region and the second halftone dot are formed. A halftone dot is arranged to overlap at the same position, and a first latent image is formed by arranging a plurality of the second halftone dots.
By forming the first halftone dot and the second halftone dot so as to have the same color under the reflected light under the visible light source, the visible image is visually recognized under the reflected light and transmitted through the base material. A printing medium having a transmission latent image, wherein the first latent image is visible when viewed under light. In the case of i), the cutout area and the second halftone dot have the same shape and size, or in the case of ii), the second hidden area and the second halftone dot have the shape and size. 2. The print medium having a transmission latent image according to claim 1, wherein the sizes are equal. 3. The print medium having a transmission latent image according to claim 1, wherein the second halftone dot is smaller than a fixed halftone dot diameter set in the first halftone dot. A transmission latent image region is formed on a substrate that is at least partially made of a colorless and / or colored transparent material and includes an infrared absorbing dye or no infrared absorbing dye;
In the transmission latent image region on the substrate, a concealing layer made of a concealing material that does not contain an infrared absorbing dye and suppresses the transmission of the transmissive material is formed.
iii) The concealing layer includes a first concealing area composed of a first concealing area ratio provided with a concealing material concealing the permeability of the base material, and the concealing material for partially exposing the base material. Or iv) the concealing layer includes a first concealment area composed of a first concealment area ratio provided with a concealment material concealing the permeability of the substrate, and the first concealment region Formed by a second concealment region comprising a second concealment area ratio lower than the concealment area ratio of
An image forming layer is formed by arranging a plurality of first halftone dots, second halftone dots, and third halftone dots on the concealment layer,
The first halftone dots form a visible image by being arranged in a plurality using colored coloring materials that do not contain an infrared absorbing dye,
The third halftone dot is disposed in the first halftone dot by a material containing an infrared absorbing dye to form a second latent image,
In the case of iii), the base material contains an infrared-absorbing dye, the second halftone dot that is not provided with a colored coloring material is formed in the third halftone dot, the cut-out region, and the second halftone dot Are arranged at the same position, and the first latent image is formed by arranging a plurality of the second halftone dots, or
In the case of iv), the second halftone dot is disposed in the third halftone dot so as to overlap with the second concealment region, and the base material contains an infrared absorbing dye. When the transmittance is 3% or more and 100% or less, and is formed of a colored material containing or not containing an infrared absorbing dye, or when the substrate does not contain an infrared absorbing dye, the transmittance is 3% or more and 100% or less. And, the first latent image is formed by arranging a plurality of the second halftone dots, the colored material containing an infrared absorbing dye,
By forming the first halftone dot, the second halftone dot, and the third halftone dot so as to have the same color under the reflected light under the visible light source, the visible image is displayed under the reflected light. The second latent image is observed when the substrate is observed under an infrared light source, and the first latent image is visible when the substrate is observed under transmitted light. A print medium having a characteristic transmission latent image. In the case of iii), the cutout area and the second halftone dot have the same shape and size, or in the case of iv), the second concealment area and the second halftone dot have the shape and 5. The print medium having a transmission latent image according to claim 4, wherein the sizes are equal. The third halftone dot is smaller than a constant halftone dot diameter set in the first halftone dot, and the second halftone dot is a constant halftone dot diameter set in the third halftone dot. 6. The print medium having a transmission latent image according to claim 4, wherein the print medium is smaller than the print medium.

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