JP2013071306A - Image forming body and personal authentication medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming body of higher resolution and higher quality.SOLUTION: The image forming body with an image formed by transferring a plurality of image component pixels as dots with a minute area onto one surface of a second substrate from a transfer foil consisting of a release layer, a structure formation layer, a transparent film layer and an adhesive layer laminated in the order on one surface of a first substrate is characterized in that the dots are transferred while keeping touch with the one surface of the second substrate and at least partially overlapping the adjacent dots, and that the transfer foil is light-transmissive.

Description

  The present invention relates to an image forming body and a personal authentication medium.

  Various security methods have been proposed for personal authentication media such as passports, visa stickers, or cards. For example, a passport currently used must be readable by both visual and optical character identification methods according to ICAO regulations. ICAO is an abbreviation for International Civil Aviation Organization. According to ICAO regulations, the materials and security used for passports are at the discretion of each country.

  A face photograph as visual confirmation information of a passport has been conventionally pasted together, but in recent years there is a tendency to digitize the photograph information and reproduce it in a passport. As this image reproduction method, for example, a thermal transfer recording method using a transfer ribbon has been studied.

  However, in consideration of the widespread use of thermal recording printers in recent years, it is not necessarily difficult to form another facial photograph on the facial photograph after removing the facial photograph from the passport.

  Patent Document 1 discloses a method of forming the same face photograph using a fluorescent material in addition to the face photograph. Patent Document 2 discloses a method for forming a facial photograph by converting a pearl pigment into a melt-type thermal transfer ink ribbon.

  However, in the method using a fluorescent material, it is necessary to use an ultraviolet lamp (black light), so that the scenes that can be authenticated are limited. A face photograph with a pearl pigment can be confirmed by visual observation, but since the particles of the pearl pigment are large, it is difficult to form a fine image.

  Further, as a technique for preventing forgery of personal authentication media, a method of hologramizing personal information such as a face photograph on demand is also considered. For example, Patent Document 3 discloses a method for hologramizing personal information by a thermal transfer method using a hologram ribbon.

  However, in this method, in order to form image information such as a facial photograph, it is necessary to obtain a high resolution by making dots very fine, and therefore there is a limit to the resolution of an on-demand hologram that can be expressed. In addition, there is a problem that the higher the resolution, the worse the image quality, and the more difficult it is to determine the authenticity by visual observation.

JP-A-7-125403 Japanese Patent Laid-Open No. 2003-170685 JP 10-049647 A

  An object of the present invention is to provide an image forming body with higher resolution and higher quality.

  In addition, the present invention provides a preventive performance against forgery, falsification, or alteration using the image forming body, and high discovery ease that can be easily found by observing a suspected fraudulent product even if those frauds are made. It is an object of the present invention to provide a personal authentication medium such as a passport, a visa, or various cards that require high security.

According to the first aspect of the present invention, one surface of the second base material from the transfer foil formed by laminating the release layer, the structure forming layer, the transparent coating layer, and the adhesive layer in this order on one surface of the first base material. An image forming body formed by transferring a plurality of pixels of image constituent elements as dots of a minute area to form an image,
The dot is in contact with one surface of the second base material and transferred at least partially overlapping with an adjacent dot, and the transfer foil is light transmissive. The

  According to a second aspect of the present invention, the personal authentication includes the image forming body according to the first aspect and a second base material onto which the image forming body is transferred from the first base material. A medium is provided.

  According to the present invention, it is possible to provide an image forming body with higher resolution and higher quality.

  According to the present invention, the image forming body is used to prevent forgery, falsification, or alteration, and even if such fraud is made, it can be easily found by observing a suspected fraudulent product. It is possible to provide a personal authentication medium such as a passport, a visa, or various cards that require high security with easy discovery.

It is a top view which shows roughly the personal authentication information medium which concerns on embodiment. It is sectional drawing which shows schematically the transfer foil which concerns on embodiment. It is sectional drawing which shows roughly the process of transferring a dot using transfer foil. FIG. 5 is a cross-sectional view schematically showing a transfer process for explaining the background in forming an image forming body according to an embodiment. It is sectional drawing which shows roughly the process of transferring two or more the image of an image component from the transfer foil which concerns on embodiment as a dot of a micro area. It is a top view showing roughly another personal authentication information medium concerning an embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same referential mark is attached | subjected to the component which exhibits the same or similar function through all the drawings, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a plan view schematically showing a personal authentication medium according to an embodiment of the present invention. A personal authentication medium 100 shown in FIG. 1 is a booklet such as a passport. FIG. 1 depicts an open booklet.

  The personal authentication medium 100 includes a signature 1 and a cover 2.

  The signature 1 is composed of one or more pieces of paper 11. Typically, an image I2 such as a character string and a background pattern is provided on the piece of paper 11. The signature 1 is formed by folding one sheet piece 11 or a bundle of a plurality of sheet pieces 11 into two. The paper piece 11 may contain an IC (integrated circuit) chip in which personal information is recorded, an antenna that enables non-contact communication with the IC chip, and the like.

  The cover 2 is folded in half. The cover 2 and the signature 1 are overlapped so that the signature 1 is sandwiched by the cover 2 with the booklet closed, and are integrated by binding or the like at the positions of the folds.

  The cover 2 displays an image including personal information. This personal information includes personal authentication information used for personal authentication. This personal information can be classified into, for example, biological information and non-biological personal information.

  The biological information is unique to the individual among the characteristics of the biological body. Typically, biological information is a feature that can be identified by optical techniques. For example, the biometric information is at least one image or pattern of a face, fingerprint, vein, and iris.

  Non-biological personal information is personal information other than biological information. For example, the non-biological personal information is at least one of name, date of birth, age, blood type, gender, nationality, address, permanent address, telephone number, affiliation, and status. The non-biological personal information may include characters input by typing, may include characters input by machine reading a handwriting such as a signature, or may include both of them. .

  In FIG. 1, the cover 2 displays images I1a, I1b, I2 and I3.

  The images I1a, I2 and I3 are images that are displayed using light absorption. Specifically, the images I1a, I2 and I3 are images that are visible when illuminated with white light and observed with the naked eye. One or more of the images I1a, I2 and I3 may be omitted.

  The images I1a, I2 and I3 can be composed of, for example, dyes and pigments. In this case, the images I1a, I2 and I3 can be formed by a thermal transfer recording method using a thermal head, an ink jet recording method, an electrophotographic method, or a combination of two or more thereof. The images I1a, I2 and I3 can be formed by forming a layer containing a heat-sensitive color former and drawing on this layer with a laser beam. Furthermore, combinations of these methods can be used. At least a part of the images I2 and I3 may be formed by a thermal transfer recording method using a hot stamp, may be formed by a printing method, or may be formed using a combination thereof.

  The image I1b is an image displayed by the hologram and / or the diffraction grating. The image I1b is formed by performing, for example, thermal transfer recording using a thermal head and thermal transfer recording using a hot stamp or a thermal roll in this order.

  The images I1a and I1b include face images of the same person. The face image including the image I1a and the face image including the image I1b may be the same or different. The face image including the image I1a and the face image including the image I1b may have the same or different dimensions. Each of the images I1a and I1b may include other biological information instead of the face image, and may further include biological information other than the face image in addition to the face image.

  The image I1b may include non-biological personal information instead of the biological information, and may further include non-biological personal information in addition to the biological information. The image I1b may include non-personal information instead of personal information, and may further include non-personal information in addition to the personal information.

  The image I2 includes non-biological personal information and non-personal information. The image I2 forms, for example, one or more of characters, symbols, codes, and marks.

  The image I3 is a background pattern. For example, the combination of the image I3 and at least one of the images I1a and I1b can make the information medium 100 more difficult to falsify.

  A transfer foil used for the image forming body of such a personal authentication medium 100 will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing a transfer foil according to the embodiment.

  The transfer foil 60 has a structure in which a peeling layer 51, a structure forming layer 52, a transparent coating layer 53, and an adhesive layer 54 are laminated in this order on one surface of a base material (first base material) 50. In FIG. 2, the transparent coating layer 53 is laminated so as to cover the entire structure forming layer 52, but the transparent coating layer 53 may be laminated on at least a part of the structure forming layer 52.

  The refractive indexes of the base material 50, the release layer 51, and the structure forming layer 52 are generally the same or close to each other, and the refractive index of only the transparent coating layer 53 is generally greatly different. As a result, when the transfer foil 60 shown in FIG. 2 is observed, since the transparent coating layer 53 is laminated so as to cover the structure forming layer 52, the emitted light resulting from the structure of the structure forming layer 52 can be observed.

  The base material 50 is formed of a plastic sheet such as polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene (PE), and the like. The thickness of the base material 50 is generally about 10 to 100 μm. The substrate 50 in the transfer foil 60 of the embodiment is preferably thin in order to improve transferability, and more preferably about 10 nm to 1 μm.

  The material of the release layer 51 is, for example, polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, methylstyrene resin, fluorene resin, PET, polypropylene, polyethylene terephthalate. What added silicone or a fluorine-type additive to thermoplastic resins, such as resin and a polyacetal resin, is preferable. Since the transfer foil 60 is transferred for each dot of a minute area as will be described later, it is necessary to have a foil cutting property in the release layer 51. In order to improve the foil breakability, it is preferable to add inorganic fine particles such as silica to the material. In addition, materials other than those described above can be used as long as the performance required for the release layer can be exhibited.

  The material of the structure forming layer 52 is, for example, polycarbonate resin, acrylic resin, fluorine acrylic resin, silicone acrylic resin, epoxy acrylate resin, polystyrene resin, cycloolefin polymer, methylstyrene resin, fluorene resin, PET, polypropylene, or other light List thermosetting resins such as curable resins, acrylonitrile styrene copolymer resins, phenol resins, melamine resins, urea resins, alkyd resins, or thermoplastic resins such as polypropylene resins, polyethylene terephthalate resins, polyacetal resins, etc. Can do. The structure forming layer 52 can be formed by molding and curing such a thermoplastic resin with a desired structure. The cured products of these resins are all light transmissive and generally have a refractive index of about 1.5.

  The thickness of the structural molding layer 52 is preferably thinner in order to improve heat resistance, foil breakage, and thermal transfer properties, and particularly preferably 1.5 μm or less.

The transparent coating layer 53 also functions as a light reflection layer, and for example, a transparent film or a metal film can be used. When the transparent coating layer 53 is a transparent film, a dielectric layer, a dielectric multilayer film, or a high refractive index material layer having a refractive index different from that of the structure forming layer 52 can be used. The transparent film is preferably formed of, for example, ZnS, TiO ₂ , PbTiO ₂ , ZrO, ZnTe, PbCrO ₄ having a refractive index of 2.0 or more. If the refractive index difference between the transparent film and the structure forming layer 52 is small, the visual effect of diffracted light due to the unevenness of the structure forming layer 52 may be weakened. Specifically, the difference in refractive index between the structure forming layer 52 and the transparent coating is preferably at least 0.5. The thickness of the transparent coating is preferably 50 nm to 100 nm.

  When the transparent coating layer 53 is a metal film, a simple substance selected from the group of chromium, nickel, aluminum, iron, titanium, silver, gold, and copper, a mixture thereof, an alloy, or the like can be used. Such a metal film preferably has a thickness of 20 nm or less because light transmittance is lost if the thickness is too large.

  The adhesive layer 54 is not particularly limited as long as it has a material for the transparent coating layer 53, other adhesive strength with the resin, and printability. The adhesive layer 54 is preferably formed of a thermoplastic resin such as polypropylene resin, polyethylene terephthalate resin, polyacetal resin, or polyester resin. Since the adhesive layer 54 requires not only adhesiveness but also a foil cutting property at the time of thermal transfer, it is more preferable to form the adhesive layer 54 by adding an inorganic material such as silica to the thermoplastic resin.

  The transfer foil 60 in which the peeling layer 51, the structure forming layer 52, the transparent coating layer 53, and the adhesive layer 54 are laminated in this order has light transmittance. The transfer foil 60 desirably has a visible light transmittance of 70% or more, more preferably 80% or more, and most preferably 90% or more.

  A process of transferring the pixels (dots) of the image constituent elements from the transfer foil shown in FIG. 2 to the substrate to be transferred will be described with reference to FIG. 3A and 3B are cross-sectional views schematically showing a transfer process of the transfer foil 60. FIG.

  As shown in FIG. 3A, the transfer foil 60 and the substrate 61 to be transferred are brought into close contact with each other, and the hot pressure 15 is applied to the region between the broken lines in the drawing. Thereafter, by peeling the substrate 50 from the transfer foil 60, only the transfer foil 60 to which the thermal pressure 15 is applied is transferred onto the transfer substrate 61 as dots 70 as shown in FIG. . At this time, the dots 70 are peeled off between the base material 50 and the peeling layer 51 and are adhered to the transfer base material 61 via the adhesive layer 54.

  As described above, since only the portion of the transfer foil 60 to which the thermal pressure 15 is applied is transferred to the transfer substrate 61, the dots 70 can be provided at desired positions on the transfer substrate 61.

  In FIG. 3, the image forming body 62 is configured by transferring the dots 70 to the transfer substrate 61. However, the image to be transferred 61 may be used as an intermediate transfer medium, and the image may be transferred to another substrate.

  Next, a process of transferring a plurality of dots from the transfer foil will be described with reference to FIG. 4A, 4B, and 4C are cross-sectional views schematically showing a transfer process for explaining the background in forming the image forming body according to the embodiment.

  First, as described above, the dots 70 a are transferred to the transfer target substrate 61 by the thermal pressure applied to the transfer foil 60. The dot 70a has the same layer structure as the dot 70 shown in FIG. 3B, but is shown in a simplified manner here. The dots 70a having such a layer structure are bonded to the transfer substrate 61 via the adhesive layer 54 (not shown), and the peeling layer 51 (not shown) exists on the outermost surface. Subsequently, the transfer foil 60 is brought into contact with the transfer target substrate 61 including the dots 70a, and the hot pressure 15 is applied to the portions of the transfer foil 60 corresponding to the dots 70a (shown in FIG. 4A). In FIG. 4A, the substrate 61 to be transferred and the transfer foil 60 are drawn apart from each other, but these members are in close contact with each other during transfer.

  When the transfer of the transfer foil 60 shown in FIG. 4A causes the dots 70b to be transferred onto the dots 70a of the substrate 50 as shown in FIG. 4B, or FIG. If the dots are not transferred onto the dots 70a of the substrate to be transferred 50 as shown in FIG. 4B or 4C depends on the material and film thickness constituting each layer of the transfer foil, or the heat and pressure applied during transfer.

  In general, when printing by a thermal transfer method using a thermal head, in order to print a higher quality image, by controlling the amount of heat and pressure at the time of printing for each dot, the diameter of each dot can be varied. Key expression is possible. Although it is possible to print an image with a binary representation of only the presence or absence of dots, the quality of the image is inferior compared to printing with a dot diameter controlled. That is, in order to be able to express a higher quality image, it is desirable to be able to transfer the transfer foil by controlling the dot diameter.

  When the conditions of the material and thickness of the transfer foil 60 are optimized, or when a certain heat pressure is applied, the dots 70b are transferred onto the dots 70a as shown in FIG. However, as described above, it is desirable to perform transfer while controlling the dot diameter in order to enable higher-quality image expression. In other words, it is necessary to control the dot diameter in order to enable the expression of a higher quality image. At this time, the applied heat pressure is not constant. For this reason, even if the material and thickness conditions of the transfer foil 60 are optimized, it is difficult to perform transfer while controlling the dot diameter. This is because when the dot 70b is transferred onto the dot 70a, a peeling layer exists on the outermost surface of the dot 70a that the dot 70b contacts. That is, the release layer is designed to be easily peeled off from other layer configurations and difficult to adhere to other layer configurations.

  Further, the surface of the dot 70a shown in FIG. 4A is shown as a curved surface shape. Actually, however, there are fine irregularities on the surface due to unevenness of the thermal pressure applied during transfer, a release layer broken during peeling, and the like. Exists. As a result, in addition to the outermost surface of the dot 70a being a release layer, the surface further has irregularities, so that it becomes difficult to transfer the dot 70b onto the dot 70a.

  When printing dots with a small diameter, the amount of heat and pressure to be applied must be reduced. For this reason, even if the conditions of the material and film thickness of the transfer foil 60 in contact with the dots 70a are optimized, when the amount of heat and pressure to be applied are small, the transfer foil 60 is formed on the dots 70a of the substrate 61 to be transferred. And remains adhered to the substrate 50 to be peeled off.

  Next, in the image forming body according to the embodiment of the present invention, a process of transferring a plurality of images of the image constituent elements from the transfer foil as dots having a small area will be described with reference to FIGS. .

  The dots 70 a are transferred to the transfer substrate 61 by the heat pressure applied to the transfer foil 60. The dot 70a has the same layer structure as the dot 70 shown in FIG. 3B, but is shown in a simplified manner here. The dots 70a having such a layer structure are bonded to the transfer substrate 61 via the adhesive layer 54 (not shown), and the peeling layer 51 (not shown) exists on the outermost surface. Subsequently, the transfer foil 60 is brought into contact with the substrate to be transferred 61 including the dots 70a, and the heat pressure 15 is applied to the region of the transfer substrate 61 and the portion of the transfer foil 60 corresponding to a part of the dots 70a adjacent thereto. Add (shown in FIG. 5A). In FIG. 5A, the substrate 61 to be transferred and the transfer foil 60 are drawn apart from each other, but these members are in close contact with each other during transfer.

  As a result of the transfer of the transfer foil 60 shown in FIG. 5A, the dot 70b becomes a region on the surface of the transfer substrate 50 and a part on the dot 70a adjacent thereto as shown in FIG. 5B. It is transcribed across.

  As described above, since the outermost surface of the dot 70a has a peeling layer with fine irregularities, it is difficult to transfer the dot 70b onto the dot 70a. However, since the surface of the dot 70b in contact with the dot 70a actually has an adhesive layer, the dot 70a and the dot 70b are sometimes bonded. However, as shown in FIG. 4C described above, when the transfer foil 60 is transferred onto the dots 70a by applying the thermal pressure 15, the transfer foil 60 may not be peeled off from the substrate 50. Both can be transferred onto the dot 70a and not transferred.

  In the image forming body according to the embodiment, as shown in FIG. 5B, the dots 70 b are transferred so as to straddle both the dots 70 a and the surface of the transferred substrate 61, so that the dots 70 b do not have a release layer. Since the substrate 70 can be firmly adhered onto the surface of the substrate 61 to be transferred, the dots 70b can be transferred to the substrate 61 to be transferred.

  Even if the adhesive force between the dot 70b and the dot 70a is weak, since the adhesion between the dot 70b and the substrate to be transferred 61 is strong, the dot 70b can be transferred to the substrate to be transferred with a good adhesive force based on the adhesion point. 61 can be transferred. That is, the dots 70b can be transferred by being well adhered to the transfer substrate 61 in a state where the dots 70b overlap with a part of the dots 70a.

  By using the transfer substrate 61 in a state where the dot 70b overlaps a part of the dot 70a, for example, a place where the original one side of the dot has a resolution of 300 dpi with 0.084 mm square is pseudo 0. A high resolution image equivalent to 0.084 mm × 0.042 mm size or 0.042 mm × 0.042 mm size, that is, 600 dpi can be obtained.

  Therefore, according to the embodiment, when transferring a plurality of dots from a transfer foil using a thermal transfer method using a thermal head or the like, adjacent dots can be partially overlapped. It becomes possible to transfer, and an image forming body with higher resolution and higher quality can be obtained.

  In the embodiment, a transfer substrate on which dots are transferred to form an image is used as the second substrate. As the second substrate, in addition to the substrate to be transferred, a laminated film in which a release layer and an image receiving layer are formed in this order on a resin film such as polyethylene terephthalate can be used.

  As the material of the release layer, the same material as the release layer of the transfer foil described above can be used. Examples of the material of the image receiving layer include thermoplastic resins such as propylene resin, polyethylene terephthalate resin, polyacetal resin, and polyester resin.

  An intermediate transfer medium is manufactured by forming a plurality of dots (pixels) on the image receiving layer of such a laminated film by the above-described method and transferring an ink ribbon as necessary. The intermediate transfer medium can perform image formation by transferring the printing information onto a paper surface as a support for transfer.

  Next, the optical characteristics of the transfer foil for transferring dots will be described.

  When the transfer foil is light-shielding, transferring the dots so as to overlap each other hinders image observation at the dot portion that is the lower layer that is superimposed.

  In embodiments, the transfer foil is light transmissive. For this reason, even if dots overlap each other, it becomes possible to cause the lower dot portion to function as a pixel. As a result, according to the embodiment, as shown in FIG. 5B described above, it is possible to place the upper layer dot 70b on the lower substrate 70a so as to partially overlap the lower layer dot 70a. By using such a light-transmitting transfer foil, a higher resolution image can be provided.

  When dots having the same layer configuration overlap, the lower layer dot has a brightness of the square of the transmittance as compared with the upper layer dot. However, human senses are the logarithm of the amount of change. For example, when the transmittance is 70%, the luminance of the lower layer dot is 49% of the luminance of the upper layer dot. In this case, since the sense that humans actually feel is the logarithm, generally, if the luminance value is about half, it does not feel that it has become so dark. Therefore, if the transfer layer has a visible light transmittance of 70% or more, it is possible to observe the emitted light from the lower layer dots without problems even in the region where the dots overlap.

  Since the transfer foil in the embodiment is light transmissive, it is possible to reduce the interval between dots and increase the resolution. That is, in order to obtain the highest resolution, it is conceivable that the dot arrangement is the dot-on-dot method. However, in the case of the dot-on-dot method, since dots to be printed later may not contact the substrate to be transferred, dot-on dots are not preferable from the viewpoint of transferability of the transfer foil as in the embodiment.

  According to the embodiment, it is possible to provide a high-quality image forming body that is brighter and has higher color reproducibility by shifting the center positions of dots transferred before and after.

  The dots correspond to the pixels of the image. When the image is input as image data and is printed by a thermal head or the like, the dots are arranged at regular intervals. When dots are arranged at regular intervals, information of image data can be easily and accurately arranged by a thermal head.

  By the way, when transferring some dots on the substrate to be transferred, the distance between the centers of the overlapping dots is shorter, and the image can be displayed with higher resolution. In such a case, when the distance between the centers of the dots is made shorter, the area where the dots transferred later are in contact with the substrate to be transferred becomes smaller. The inventor has confirmed through experiments that the dots can be stably transferred by setting the area where the dots transferred after being overlapped to be in contact with the substrate to be transferred to ½ or more of the total area of the dots. Therefore, by setting the distance between the centers of the overlapping dots to be equal to or greater than the maximum value of the radius when the dots are circular, it is possible to provide an image forming body with higher resolution and higher quality.

  The dot size transferred from the transfer foil in the embodiment is not particularly limited, but when forming a personal face image or the like, the length of one side of the dot is 0.042 mm to 0.084 mm (300 dpi). It is preferable that If the dot size is larger than this, the face image becomes rough, and it may be difficult to determine authenticity as compared with an actual face photograph. Further, when the dot size is smaller than this, the foil cutting property of the transfer foil and the variation at the time of transfer increase, and it becomes difficult to express smoothly.

  In the image forming body according to the embodiment, by forming a diffraction grating in the structure forming layer of the transfer foil, it is possible to express an image that can be observed as diffracted light by dots transferred from the transfer foil. Since the transfer foil used in the embodiment can be transferred using a thermal transfer method, by using this transfer foil and a general color ribbon in combination, an image with normal ink and an image that can be observed as diffracted light can be transferred to the same transferred substrate. It can be easily produced on a material.

  Special knowledge and technology are required to form a diffraction grating having a good optical function in the structure forming layer. For this reason, when the structure forming layer of the transfer foil includes the diffraction grating, forgery or imitation of the transfer foil becomes difficult.

  Further, by transferring dots using a plurality of transfer foils having different structures and forms of the structure forming layer, it is possible to express more various visual effects. For example, if the direction in which light is emitted from each structure forming layer is different, it is possible to provide an image forming body having a changing effect for displaying different images depending on the observation angle. In this case, it is possible to express the changing more effectively by transferring adjacent dots that are different from each other in at least some of the structure forming layers.

  In a dot configuration where two dots with small dot diameters and structures different from each other are adjacent, only one dot light can be observed at a certain observation angle, and only the other dot light can be observed at a different observation angle. Since the diameter cannot be visually observed, it is possible to observe as if different lights are emitted at different observation angles at the same location. Therefore, it is possible to provide a higher quality image forming body by arranging the dots having the structure forming layers having different structures adjacent to each other.

  Further, in the adjacent dots, the spatial frequency of the diffraction grating of the structure forming layer constituting them can be expressed by three or more kinds of colors of R, G and B at a certain angle. It becomes possible. That is, by using three or more spatial frequencies, it is possible to express a full color image that can be observed as diffracted light, and to provide a higher quality image forming body. In this case, by arranging dots so that at least a part of R, G, and B are adjacent to each other, full color display can be expressed in units of pixels. In this case, the R, G, and B components of the full-color original image that is desired to be displayed need only be extracted and regularly arranged, so that the image processing load can be greatly reduced.

  Further, in addition to R, G, and B, there may be a structure that displays other colors such as C, M, and Y. By increasing the number of colors, the color gamut of the image displayed by the image forming body can be further expanded.

  In the image forming body according to the embodiment, at least some of the plurality of dots are transferred from one type of transfer foil among the plurality of transfer foils each having a diffraction grating having three or more types of spatial frequencies formed in the structure forming layer. The dots may overlap at least partially with the two or more types of dots transferred from the remaining two or more types of transfer foils. An image formed from such dots can emit red, green, and blue diffracted light at specific angles.

  A method of forming the face image of the personal authentication medium described above by transferring three transfer foils having three types of spatial frequencies of the diffraction grating of the structure forming layer will be briefly described. For example, full-color image data of general three primary colors RGB as displayed on a personal computer monitor is input into a computer program, and the image data is decomposed into RGB. Each data is output to a program of a thermal transfer device such as a thermal head, and the three transfer foils (three types of transfer foils corresponding to RGB) prepared in advance are used according to the data corresponding to each color, for example. Transfer onto the image receiving layer of the intermediate transfer medium. As a result, a full-color face image as if the photograph was emitted as it is can be transferred to the intermediate transfer medium by the RGB diffracted light. Thereafter, by transferring the printing information of the intermediate transfer medium onto a paper support, for example, a paper surface, a full-color face image can be expressed on the paper.

  As described above, the personal authentication medium 100 as a passport is exemplified in the embodiment, but the above-described technique can also be applied to a personal authentication medium other than the passport. For example, this technique can be applied to various cards such as a visa and an ID card.

  In the personal authentication medium 300 shown in FIG. 6, a print layer 21 made of a person image is formed. The image forming body 62 is further transferred to the personal authentication medium 300 for counterfeiting prevention or identification, and the image of the image forming body 62 is also a person image. In the case of the personal authentication medium 300 shown in FIG. 6, the print image of the print layer 21 and the image of the image forming body 62 are the same. In this case, if the print image of the print layer 21 and the image of the image forming body 62 are the same (actual), even if the information of the print image of the print layer 21 is falsified, Since the information of the image forming body 62 must be the same, the image forming body 62 also needs to be tampered with the same pattern, and forgery or imitation becomes difficult.

  Further, since the authenticity can be determined by comparing the print image of the print layer 21 with the image of the image forming body 62, more accurate authentication can be performed for an examiner who performs personal identification. Further, since the authenticity determination method is a comparatively simple method by comparing images, not only the examiner but anyone can easily determine the authenticity.

  The image forming body 62 included in the personal authentication medium 300 shown in FIG. 6 is composed of an image made up of a person image. In this case, forgery or imitation of the personal authentication medium can be made more difficult, but it can also be applied to information media other than the personal authentication medium.

  The material of the base material to which the image forming body is attached may not be paper such as natural paper and synthetic paper. For example, the material of the base material to which the image forming body 62 is attached is a synthetic resin such as polyethylene terephthalate resin (thermoplastic PET), polyvinyl chloride resin, thermosetting polyester resin, polycarbonate resin, polymethacrylic resin and polystyrene resin, glass, and the like. Ceramics such as ceramics and porcelain, or metal materials such as simple metals and alloys may be used.

  In the embodiment, personal authentication media such as a passport and an ID card are exemplified. However, the above-described technique can also be applied to information media other than the personal authentication media. That is, the above-described technique may be used for purposes other than personal authentication.

  Examples of the present invention will be described below. In this embodiment, a case where the transfer substrate is an intermediate transfer medium will be described.

Example 1
<Production of transfer foil>
First, a polyethylene terephthalate film having a thickness of 25 μm was used as a substrate, and a release layer and a structure forming layer were printed in this order on the film with a gravure coater. After drying in the oven, the thickness of the release layer was 0.6 μm, and the thickness of the structure forming layer was 0.7 μm. Since the structure forming layer is a two-component thermosetting resin of acrylate / isocyanate, there is no problem even if the thickness is less than 1 μm. Subsequently, the plate having the diffraction grating formed on the structure forming layer on the film was hot-pressed with a roll embossing device to form the unevenness of the diffraction grating.

  Next, a transparent thin film layer was deposited by performing ZnS vapor deposition on the structure forming layer. The thickness of the transparent thin film layer was 80 nm. Subsequently, an adhesive layer having a thickness of 0.6 μm was printed on the transparent thin film layer, and a release layer, a structure forming layer, a transparent thin film layer, and an adhesive layer were laminated in this order on the film.

  Next, the laminated film was slit into a transfer ribbon-sized width and divided into pieces to produce a transfer foil.

  In addition to the transfer foil, known yellow, magenta, cyan, and black ink ribbons were prepared.

<Preparation of intermediate transfer medium>
A polyethylene terephthalate film having a thickness of 19 μm was used as a substrate, and a release layer and an image receiving layer were printed in this order on the film with a gravure coater. After drying in the oven, the release layer had a thickness of 1.0 μm, and the image receiving layer had a thickness of 4.0 μm. As the release layer, an acrylic resin made by Mitsubishi Rayon was used. As the image receiving layer, an epoxy resin manufactured by Mitsubishi Chemical was used.

  Next, a ribbon-shaped transfer foil prepared in advance was transferred to a target position on the image receiving layer using a thermal head to express a face image. As the transfer foil, three types of foils were used in which diffraction gratings having spatial frequencies of 1150 / mm, 1310 / mm, and 1550 / mm were formed on the structure forming layer, respectively.

  As for the face image information, a face photograph of a person as a subject was taken in advance, and the position where each diffraction grating cell was transferred from the photographed photograph was set by a program on a computer. The expression of the face image was performed by outputting to the control unit of the thermal head based on this program.

  Further, the transfer of the face image by the thermal head was performed by transferring the dots from the transfer foil so as to partially overlap the image receiving layer and the adjacent dots. At this time, printing was performed with a maximum dot diameter of about 0.084 μm (equivalent to 300 dpi) and an interval between dot center positions of 0.042 μm (equivalent to 600 dpi).

  Next, an ink ribbon prepared in advance was transferred onto the image receiving layer using a thermal head, and a face photograph and character information were printed to produce an intermediate transfer medium.

  The personal authentication medium was obtained by transferring the printing information of the obtained intermediate transfer medium onto a paper surface as a support for transfer.

(Reference Example 1)
In the same manner as in Example 1, a thermal foil was used to print a transfer foil on paper as a support by a dot-on-dot method. As the transfer foil, three types of foils in which diffraction gratings having spatial frequencies of 1150 lines / mm, 1310 lines / mm, and 1550 lines / mm were respectively formed on the structure forming layer were used as in Example 1. At this time, printing with a maximum dot diameter of about 0.084 μm (corresponding to 300 dpi) and an interval between dot center positions of 0.084 μm (corresponding to 300 dpi) and a maximum dot diameter of about 0.042 μm (corresponding to 600 dpi) ), Printing was performed at an interval between the center positions of the dots of 0.042 μm (equivalent to 600 dpi).

  In order to display a full color using three types of dots having different spatial frequencies, one pixel is represented by three dots. When printing with a maximum dot diameter of about 0.084 μm (corresponding to 300 dpi) and an interval between dot center positions of 0.084 μm (corresponding to 300 dpi), the dots can be visually recognized by observation from a distance of 30 cm from the information medium. Therefore, it was found that a high-resolution image was not made.

  On the other hand, in the case of the dot-on-dot method of Reference Example 1, it is the same that one pixel is expressed by three dots, but since the three dots are printed at the same location, the area is one dot. . When printing with a maximum dot diameter of about 0.042 μm (equivalent to 600 dpi) and an interval between dot center positions of 0.042 μm (equivalent to 600 dpi), the dots are not visible when viewed from a distance of 30 cm from the information medium. It was found that high-resolution images could be produced. However, it has been found that the color reproducibility of the image is lowered due to the low accuracy of transferring dots having a small diameter in an overlapping manner.

  In contrast, the personal authentication medium on which the image according to Example 1 (the maximum value of the dot diameter is about 0.084 μm (equivalent to 300 dpi) and the interval between the center positions of the dots is 0.042 μm (equivalent to 600 dpi)) is observed. As a result, it was found that a high-resolution full-color image was produced with good color reproducibility. In observation from a distance of 30 cm from the personal authentication medium, the dots were not visible.

  As described above, it has been found that the personal authentication medium according to the present invention can produce a high-resolution image with good color reproducibility.

  In addition, the image forming body according to the present invention has a preventive performance against forgery, tampering or alteration, and visibility so that it can be easily found by observing a suspected fraudulent product even in the event that such fraud is made. It has been found that it is possible to provide a personal authentication medium having high security by combining the high security with excellent easy-to-find performance and using the image forming body.

  DESCRIPTION OF SYMBOLS 1 ... Signature, 2 ... Cover, 11 ... Paper piece, 15 ... Hot pressure, I1a, I1b, I2, I3 ... Image, 21 ... Print layer, 50 ... Base material, 51 ... Release layer, 52 ... Structure formation layer, 53 DESCRIPTION OF SYMBOLS ... Transparent film layer, 54 ... Adhesive layer, 60 ... Transfer foil, 61 ... Substrate to be transferred, 62 ... Image forming body, 70, 70a, 70b ... Dot (pixel), 100, 300 ... Personal authentication medium.

Claims (13)

From the transfer foil formed by laminating the release layer, the structure forming layer, the transparent coating layer, and the adhesive layer in this order on one surface of the first substrate, the pixels of the image constituent elements are arranged in a small area on one surface of the second substrate. An image forming body in which a plurality of dots are transferred to form an image,
The dot is in contact with one surface of the second base material, transferred at least partially overlapping with an adjacent dot, and the transfer foil is light transmissive.   The image forming body according to claim 1, wherein the transfer foil has a visible light transmittance of 70% or more.   The image forming body according to claim 1, wherein the transparent coating layer is a transparent material having a refractive index different from that of the structure forming layer.   The image forming body according to claim 1, wherein the transparent coating layer is a metal coating.   5. The image forming body according to claim 1, wherein the center positions of the plurality of dots are arranged at regular intervals, and the arrangement interval is smaller than the maximum value of the dot size.   6. The image forming body according to claim 1, wherein an interval between center positions of the plurality of dots is equal to or greater than a maximum value of a radius of the dots.   The image forming body according to claim 1, wherein the structure forming layer is formed with a diffraction grating.   An image forming body in which an image is formed by transferring a plurality of the transfer foils, wherein the plurality of transfer foils are formed by forming diffraction gratings having three or more types of spatial frequencies on the structure forming layer, respectively. The image forming body according to claim 1, wherein the image forming body is an image forming body.   An image forming body formed by transferring a plurality of the transfer foils to form an image, wherein the plurality of transfer foils each having a diffraction grating having three or more types of spatial frequencies formed on the structure forming layer are formed at a specific angle. 9. The image forming body according to claim 8, wherein red, green and blue diffracted lights are respectively emitted.   An image forming body in which an image is formed by transferring a plurality of the transfer foils, wherein at least a part of the plurality of dots is a plurality of diffraction gratings each having three or more types of spatial frequencies formed in the structure forming layer. 10. The dots transferred from one transfer foil of the transfer foils are at least partially overlapped with two or more dots transferred from the remaining two or more transfer foils. Image forming body.   The image forming body according to claim 1, wherein the image is an image including personal information.   The image forming body according to claim 11, wherein the image including the personal information is a face image.   13. A personal authentication medium comprising: the image forming body according to claim 1; and a second base material onto which the image forming body is transferred from the first base material.

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