JP2011123365A - Image display material, transfer foil and personal identification medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an image of high picture quality exhibiting a complicated visual effect. <P>SOLUTION: An image display material 22 is provided, including: a relief type first diffraction structure 224a where a first image is displayed as a diffraction image when the structure is observed in a first direction under specific illumination conditions, and when the structure is observed in a second direction different from the first direction under the above illumination conditions, the first image is not displayed as a diffraction image or displayed as a darker diffraction image compared to the first image observed in the first direction; and a relief type second diffraction structure 224b where a second image different from the first image is displayed as a diffraction image when the structure is observed in the second direction under the above illumination conditions, and when the structure is observed in the first direction under the above illumination conditions, the second image is not displayed as a diffraction image or displayed as a darker diffraction image compared to the second image observed in the second direction. The second diffraction structure 224b has light-transmitting property, and at least partially opposes to the first diffraction structure 224a in a front side of the first diffraction structure 224a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image display technique that can be used for personal authentication, for example.

  Many personal authentication media such as passports and ID (identification) cards use facial images to enable visual personal authentication.

  For example, in a passport, conventionally, photographic paper on which a face image is printed is pasted on a booklet. However, such passports may be tampered with by reprinting photographic prints.

  For these reasons, in recent years, there is a tendency to digitize facial image information and reproduce it on a booklet. As this image reproduction method, for example, a thermal transfer recording method using a transfer ribbon has been studied.

  However, recently, thermal transfer recording type printers using sublimation dyes or colored thermoplastic resins are widely used. Considering this situation, it is not always difficult to remove a face image from a passport and record another face image on the face image.

  Patent Document 1 describes that a face image is recorded by the method described above, and a face image is recorded thereon using fluorescent ink. Patent Document 2 describes that a face image is recorded using an ink containing a colorless or light-colored fluorescent dye and a colored pigment. Further, Patent Document 3 describes that a normal face image and a face image formed using a pearl pigment are arranged side by side.

  When these technologies are applied to a passport, the alteration becomes more difficult. However, a face image recorded using a fluorescent material cannot be observed unless a special light source such as an ultraviolet lamp is used. In addition, although a face image formed using a pearl pigment can be visually recognized with the naked eye, it is difficult to form a high-definition image using this because the pearl pigment has a large particle size.

  Patent Document 4 describes that a multilayer film is transferred from a transfer ribbon onto a substrate. Further, Patent Document 4 describes that multilayer films having different display colors are juxtaposed in order to display a color image.

  Usually, an image displayed by a multilayer film pattern cannot be reproduced using a generally available transfer ribbon, and can be visually recognized with the naked eye. Further, according to the method of transferring a multilayer film, it is possible to achieve an excellent image quality as compared with the case of using a pearl pigment. This technique is suitable for recording images on demand, and is expected to be applied to recording personal information.

JP 2000-141863 A JP 2002-226740 A Japanese Patent Laid-Open No. 2003-170685 JP 10-49647 A

  The present inventors believe that if an image showing a more complicated visual effect can be displayed with high image quality, the effect of suppressing fraud is further improved. Therefore, the present invention is capable of displaying an image showing a complicated visual effect with high image quality.

The first aspect of the present invention displays a first image as a diffraction image when observed from a first direction under a specific illumination condition, and is different from the first direction under the illumination condition. A relief-type first diffractive structure that does not display the first image as a diffraction image when observed from a direction or displays the first image as a darker diffraction image than when observed from the first direction; ,
When observed from the second direction under the illumination conditions, a second image different from the first image is displayed as a diffraction image, and when observed from the first direction under the illumination conditions A relief type second diffractive structure that does not display the second image as a diffracted image or displays the second image as a darker diffracted image as compared with a case where the second image is observed from the second direction. The diffractive structure is an image display body that is light transmissive and is at least partially facing the first diffractive structure in front of the first diffractive structure.

  The second aspect of the present invention includes a first image display layer having a first reflective layer having the first diffractive structure provided on one main surface and having a shape corresponding to the first image, The second diffractive structure is provided on the main surface of the first reflection layer, and includes a second reflective layer having optical transparency, and has a shape corresponding to the second image, and at least the first image display layer and It is the image display body which concerns on the 1st side surface which comprised the 2nd image display layer which overlapped partially.

  According to a third aspect of the present invention, the first image display layer is constituted by a plurality of first dot-like portions whose centers are located on lattice points of a virtual planar lattice, and the second image The display layer is configured by a plurality of second dot-shaped portions whose centers are located on lattice points of a virtual planar lattice, and the plurality of first dot-shaped portions and the plurality of second dot-shaped portions. The part is an image display body according to the second side surface at least partially overlapping.

  According to a fourth aspect of the present invention, the first image includes first and second parts having the same display color on the inner side and the outer side of the contour of the second image, respectively, and corresponds to the first part. The area is an image display body according to a third side surface in which the surface density of the first dot-shaped portion is higher than that of the area corresponding to the second portion.

  According to a fifth aspect of the present invention, there is provided an image display body according to any one of the first to fourth aspects, wherein a stereoscopic image is displayed by the first and second images as diffraction images.

  A sixth aspect of the present invention is the image display body according to the fifth aspect, wherein the stereoscopic image includes personal information.

  A seventh aspect of the present invention is the image display body according to the sixth aspect, wherein the personal information includes a face image.

  According to an eighth aspect of the present invention, there is provided a transfer foil comprising the image display body according to any one of the first to seventh side faces and a support body that releasably supports the image display body.

  A ninth aspect of the present invention is a personal authentication medium comprising the image display body according to any one of the first to seventh aspects and a base material supporting the image display body.

  According to the present invention, an image showing a complicated visual effect can be displayed with high image quality.

  The image display according to the first aspect of the present invention includes relief-type first and second diffractive structures. The first diffractive structure displays a first image as a diffraction image when observed from a first direction under a specific illumination condition, and is observed from a second direction different from the first direction under the illumination condition. In this case, the first image is not displayed as a diffraction image, or the first image is displayed as a darker diffraction image as compared with the case where the first image is observed from the first direction. The second diffractive structure displays a second image different from the first image as a diffracted image when observed from the second direction under the previous illumination condition, and is observed from the first direction under the illumination condition. In this case, the second image is not displayed as a diffraction image, or is displayed as a darker diffraction image as compared with the case where the second image is observed from the second direction. Therefore, for example, a three-dimensional image can be displayed on the image display body, or different images can be displayed depending on the observation direction. That is, this image display body shows a complicated visual effect.

  When the first and second diffractive structures are provided on the same plane, the first diffractive structure is divided into a number of first substructures in order to display both the first and second images in the same region. It is necessary to divide the second diffractive structure into a plurality of second substructures and arrange them alternately. In this case, to achieve high resolution, the first and second substructures must be significantly smaller. Such an image display is particularly difficult to manufacture in a process of recording an image on demand. Therefore, it is difficult to achieve high resolution.

  On the other hand, in the image display body according to the first side surface, the second diffractive structure has optical transparency, and at least partially faces the first diffractive structure in front of the first diffractive structure. When this configuration is adopted, it is not necessary to arrange the first and second substructures alternately. Accordingly, the above-described problem does not occur, and high resolution can be achieved relatively easily. That is, an image can be displayed with high image quality.

  The image display body according to the second aspect of the present invention employs the configuration described above for the image display body according to the first aspect, and at least partially includes the first image display layer, the first image display layer, and the like. And a second image display layer overlapping each other. The first image display layer includes a first reflective layer provided with a first diffractive structure on one main surface, and has a shape corresponding to the first image. The second image display layer is provided with a second diffractive structure on one main surface, includes a second reflective layer having light transmittance, and has a shape corresponding to the second image. When this configuration is adopted, for example, an image can be recorded using a transfer foil. Therefore, this configuration is suitable for the process of recording images on demand.

  The image display body according to the third aspect of the present invention employs the configuration described above for the image display body according to the second aspect, and the first image display layer has a virtual planar lattice at each center. The second image display layer is composed of a plurality of second dots whose centers are located on the lattice points of a virtual planar lattice. It is comprised by the shape part. The plurality of first dot portions and the plurality of second dot portions overlap at least partially. This configuration is suitable for a process of recording an image by thermal transfer using a thermal head.

  The image display body according to the fourth aspect of the present invention employs the configuration described above for the image display body according to the third aspect, and the first image includes first and second portions having the same display color. Are included inside and outside the contour of the second image, respectively. And in the area | region corresponding to a 1st part, the surface density of a 1st dot-shaped part is larger compared with the area | region corresponding to a 2nd part. This configuration is advantageous in reducing the influence of the second reflective layer on the image quality of the first image as the diffraction image.

  The image display according to the fifth aspect of the present invention employs the configuration described above for the image display according to the first aspect, and displays a stereoscopic image by the first and second images as diffraction images. To do. An image display for displaying a stereoscopic image is difficult to counterfeit.

  The image display according to the sixth aspect of the present invention employs the configuration described above for the image display according to the fifth aspect, and the stereoscopic image includes personal information. It is extremely difficult to falsify personal information displayed by a stereoscopic image.

  The image display body according to the seventh aspect of the present invention employs the configuration described above for the image display body according to the sixth aspect, and the personal information includes a face image. A face image is common as biometric information, and is suitable for visual personal authentication.

  The transfer foil according to the eighth aspect of the present invention includes the image display body according to any one of the first to seventh side surfaces, and a support that releasably supports the image display body. When the image display body is transferred from the support of such a transfer foil onto the base material, the surface of the base material is compared with the case where each of the first and second diffractive structures is directly formed on the base material. The influence of unevenness on the image quality can be reduced.

  A personal authentication medium according to a ninth aspect of the present invention includes the image display body according to any one of the first to seventh aspects. Therefore, this personal authentication medium is difficult to tamper with in addition to displaying an image showing a complicated visual effect with high image quality.

The top view which shows roughly the personal authentication medium which concerns on 1 aspect of this invention. The top view which expands and shows a part of personal authentication medium shown in FIG. Sectional drawing along the III-III line of the personal authentication medium shown in FIG. The top view which shows schematically the diffraction structure which the image display body of the personal authentication medium shown in FIG.2 and FIG.3 contains. The top view which shows schematically the other diffraction structure which the image display body of the personal authentication medium shown in FIG.2 and FIG.3 contains. The top view which expands and shows a part of personal authentication medium which concerns on a comparative example. Sectional drawing along the VII-VII line of the personal authentication medium shown in FIG. Sectional drawing which shows schematically an example of the secondary transfer foil which can be used for manufacture of the personal authentication medium shown in FIG. 1 thru | or FIG. The top view which expands and shows a part of personal authentication medium which concerns on one modification. Sectional drawing which expands and shows a part of personal authentication medium which concerns on another modification.

  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 one aspect of the present invention.
A personal authentication medium 100 shown in FIG. 1 is a booklet such as a passport. FIG. 1 shows the booklet in an open state.

This 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, a print pattern 12 such as a character string and a background pattern is provided on the paper piece 11. The signature 1 is formed by folding one paper piece 11 or a bundle of a plurality of paper pieces 11 into two. The paper piece 11 may include 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 between the covers 2 in a state where the booklet is 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, biometric 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 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. Alternatively, the images I1a, I2 and I3 can be formed by forming a layer containing a thermal color former and drawing on this layer with a laser beam. Alternatively, a combination 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 a diffraction structure such as a diffraction grating and a hologram. As will be described in detail later, the image I1b is formed, for example, by performing thermal transfer recording using a thermal head and thermal transfer recording using a hot stamp or a heat roll in this order.

  The images I1a and I1b include face images of the same person. The face image included in the image I1a and the face image included in the image I1b may be the same or different. The face image included in the image I1a and the face image included in 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 11b 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. In addition, the image 11b 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, when the image I3 and at least one of the images 11a and 11b are combined, the personal authentication medium 100 can be made more difficult to falsify.

Next, the structure of the cover 2 will be described with reference to FIGS.
FIG. 2 is an enlarged plan view showing a part of the personal authentication medium shown in FIG. 3 is a cross-sectional view of the personal authentication medium shown in FIG. 2 taken along the line III-III. FIG. 4 is a plan view schematically showing a diffractive structure included in the image display body of the personal authentication medium shown in FIGS. 2 and 3. FIG. 5 is a plan view schematically showing another diffractive structure included in the image display body of the personal authentication medium shown in FIGS.

  The X direction is a direction parallel to the display surface of the image display body, the Y direction is a direction parallel to the display surface of the image display body and a direction perpendicular to the X direction, and the Z direction is X and X. This is a direction perpendicular to the Y direction. Also, the structure shown in FIGS. 2 and 3 is a portion of the cover 2 corresponding to the image I1b.

As shown in FIG. 3, the cover 2 includes a cover main body 21 and an image display body 22.
The cover main body 21 is a base material of the personal authentication medium 100 and is typically a piece of paper. The cover main body 21 may have a single layer structure or a multilayer structure. The cover body 21 is folded in half so as to sandwich the signature 1 in a state where the personal authentication medium 100 is closed.

  The image display body 22 is a layer having a multilayer structure. The image display body 22 is affixed to the main surface of the cover body 21 that faces the signature 1 when the personal authentication medium 100 is closed.

  The image display body 22 includes an image display layer (not shown) that displays at least a part of the images I1a, I2 and I3. The image displayed by the image display layer typically includes an image I1a.

  The image display layer displays at least a part of the images I1a, I2 and I3 using light absorption. The image display layer has a pattern shape corresponding to at least a part of the images I1a, I2 and I3. This image display layer can be composed of at least one of a dye and a pigment and an arbitrary resin. Such an image display layer can be obtained, for example, by using 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. Further, at least a part of the image display layer may be formed by a thermal transfer recording method using a hot stamp, may be formed by a printing method, or may be formed by using a combination thereof.

  This image display layer may not be patterned. That is, the image display layer may be a continuous film. In this case, the image display layer can be obtained, for example, by forming a layer containing a heat-sensitive color former and drawing on this layer with a laser beam.

  This image display layer can be omitted. For example, the image display layer may be provided on the cover body 21 without being a component of the image display body 22.

  As shown in FIG. 3, the image display 22 further includes image display layers 220 a and 220 b, a resin layer 225, and a protective layer 227.

  The image display layer 220a forms a pattern. The image display layer 220a displays the first image as a diffraction image when observed from the first direction under a specific illumination condition. Then, the image display layer 220a does not display the first image as a diffraction image when viewed from a second direction different from the first direction under the previous illumination conditions, or the first image is displayed as the first image. It is displayed as a darker diffraction image compared to the case of observation from the direction. Here, it is assumed that the first image displayed as the diffraction image by the image display layer 220a is the parallax image for the right eye of the image I1b.

  The image display layer 220a includes a diffraction structure forming layer 223a, a reflective layer 224a, a resin layer 225a, and a protective layer 227a.

  The diffractive structure forming layer 223a has optical transparency, particularly visible light transmission, and is typically a transparent layer. On one main surface of the diffraction structure forming layer 223a, a diffraction grating is provided as a relief type diffraction structure. As shown in FIG. 4, this diffractive structure is composed of a plurality of grooves Ga provided on one main surface of the diffractive structure forming layer 223a. The grooves Ga have the same shape and are arranged in parallel with each other at a constant pitch. The length direction of the groove Ga is inclined counterclockwise with respect to the X direction. In the example shown in FIG. 4, the groove Ga is curved in an arc shape, but the groove Ga may not be curved.

  Examples of the material of the diffraction structure forming layer 223a include thermoplastic resins such as polyurethane resin, polycarbonate resin, polystyrene resin and polyvinyl chloride resin, unsaturated polyester resin, melamine resin, epoxy resin, urethane acrylate, urethane methacrylate, polyol acrylate. Thermosetting resins such as polyol methacrylate, melamine acrylate, melamine methacrylate, triazine acrylate and triazine methacrylate, mixtures thereof, or thermoformable materials having radically polymerizable unsaturated groups can be used. The diffraction structure forming layer 223a may be formed using a resin having photocurability. Note that the diffractive structure forming layer 223a obtained using such a transparent resin typically has a refractive index in the range of 1.3 to 1.7 for light having a wavelength of 550 nm.

  The reflective layer 224a is interposed between the cover body 21 and the diffractive structure forming layer 223a. The reflective layer 224a is formed on the diffractive structure forming layer 223a. The reflective layer 224a covers at least part of the surface of the diffraction structure forming layer 223a where the relief structure is provided.

  As the reflective layer 224a, for example, a transparent reflective layer or an opaque reflective layer can be used. Such a reflective layer 224a can be formed by, for example, a vacuum film forming method such as vacuum deposition or sputtering. When the reflective layer 224a contains a resin, the reflective layer 224a may be formed by applying or printing.

  When a transparent reflective layer is used as the reflective layer 224a, even if a pattern such as a pattern and characters is arranged on the back side of the reflective layer 224a, it can be visually recognized from the front side of the image display body 22.

  The transparent reflective layer may have a single layer structure or a multilayer structure. In the latter case, the transparent reflective layer may be designed so as to repeatedly cause reflection interference. As a material of the transparent reflective layer, for example, a transparent dielectric such as zinc sulfide and titanium dioxide can be used.

  The transparent reflective layer having a single layer structure made of a transparent dielectric has a refractive index different from that of the diffraction structure forming layer 223a. Typically, a single-layer transparent reflection layer made of a transparent dielectric has a higher refractive index with respect to light having a wavelength of 550 nm than the diffraction structure forming layer 223a.

  The transparent reflective layer having a multilayer structure made of a transparent dielectric has a refractive index different from that of the diffractive structure forming layer 223a at the portion in contact with the diffractive structure forming layer 223a. The transparent reflective layer having a multilayer structure made of a transparent dielectric typically has a refractive index with respect to light having the above-mentioned wavelength of the layer closest to the diffractive structure forming layer 223a. Greater than rate.

  A metal layer may be used as the transparent reflective layer. As a material for the metal layer, for example, a single metal such as aluminum, tin, copper, silver, gold, iron, chromium, nickel and copper, or an alloy thereof can be used. The metal layer is light-shielding when it is thick, but becomes transparent when it is thin. For example, in the case of an aluminum layer having a thickness in the range of 20 to 40 nm, the metallic luster can be observed under certain observation conditions, but the background can be seen through when the observation angle is changed.

  A thicker metal layer can also be used as the transparent reflective layer. For example, a relatively thick metal layer is formed, and a large number of openings having a diameter or width that are difficult to identify with the naked eye are provided. For example, this metal layer is patterned into a halftone dot or a line. Thereby, a transparent reflective layer made of a metal material can be obtained.

  As the material of the opaque metal reflection layer, for example, the materials described above with respect to the metal layer as the transparent reflection layer can be used. The opaque metallic reflective layer is typically not provided with an opening having a diameter or width that is difficult to identify with the naked eye, and has a sufficient thickness to block light.

  A layer containing a transparent resin and particles dispersed therein may be used as the transparent reflective layer or the opaque reflective layer. As the particles, for example, particles made of a metal material such as a single metal and an alloy, or particles made of a transparent dielectric such as a transparent metal oxide and a transparent resin can be used. In the transparent resin, flakes may be dispersed instead of dispersing the particles.

  The resin layer 225a is formed on the reflective layer 224a. The resin layer 225a can be omitted.

  The resin layer 225a is made of, for example, a thermoplastic resin. Examples of the material of the resin layer 225a include urethane resin, butyral resin, polyester resin, polyvinyl chloride resin such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer, polyurethane resin, epoxy resin, chlorinated polypropylene, and acrylic resin. , Polystyrene, polyvinylbenzene, styrene-butadiene copolymer resin, vinyl resins such as polyvinyl resin obtained from styrene and alkyl methacrylate (wherein the alkyl group has 2 to 6 carbon atoms), rubber materials, or these Mixtures containing two or more can be used.

  The resin layer 225a is made of wax, higher fatty acids such as stearic acid, metal salts and esters thereof, plasticizers, organic fillers made of organic materials such as polytetrafluoroethylene, polyethylene, silicone resins and polyacrylonitrile, and silica. One or more inorganic fillers made of an inorganic material may be added.

  The protective layer 227a is interposed between the cover body 21 and the diffractive structure forming layer 223a. The protective layer 227a can be omitted.

  The protective layer 227a is made of, for example, a resin such as a thermoplastic resin, a thermosetting resin, and an ultraviolet ray or an electron beam curable resin. When the pattern of the image display layer 220a is formed using the transfer foil, it is preferable to use a thermoplastic resin from the viewpoints of flexibility and foil breakability.

  Examples of this thermoplastic resin include polyacrylate resin, chlorinated rubber resin, vinyl chloride-vinyl acetate copolymer resin, cellulose resin, chlorinated polypropylene resin, epoxy resin, polyester resin, nitrocellulose resin, A thylene acrylate resin, a polyether resin, a polycarbonate resin, or a mixture thereof can be used. In consideration of foil cutting properties and abrasion resistance, this resin includes waxes such as petroleum waxes and plant waxes, higher fatty acids such as stearic acid, metal salts thereof, esters and silicone oils and other lubricants, polytetrafluoroethylene One or more of an organic filler made of an organic material such as polyethylene, silicone resin and polyacrylonitrile, and an inorganic filler made of an inorganic material such as silica may be added.

  The image display layer 220b forms a pattern and at least partially overlaps the image display layer 220a. Here, the image display layer 220b partially overlaps the image display layer 220a in front of the image display layer 220a.

  The image display layer 220b displays a second image different from the first image as a diffraction image when observed from the second direction under the illumination conditions described above. Then, the image display layer 220b does not display the second image as a diffraction image when observed from the first direction under this illumination condition, or compared with the case where the second image is observed from the second direction. And displayed as a darker diffraction image. Here, it is assumed that the second image displayed as the diffraction image by the image display layer 220b is the left-eye parallax image of the image I1b.

  The right-eye parallax image and the left-eye parallax image are, for example, images obtained by simultaneously photographing the same subject from different positions. The observer perceives a stereoscopic image by observing the parallax image for the right eye and the parallax image for the left eye with the right eye and the left eye, respectively.

  The image display layer 220b includes a diffraction structure forming layer 223b, a reflective layer 224b, a resin layer 225b, and a protective layer 227b.

  The diffractive structure forming layer 223b has light transmission properties, particularly visible light transmission properties, and is typically transparent. On one main surface of the diffraction structure forming layer 223b, a diffraction grating is provided as a relief type diffraction structure. As shown in FIG. 5, the diffractive structure includes a plurality of grooves Gb provided on one main surface of the diffractive structure forming layer 223b. The grooves Gb have the same shape and are arranged in parallel with each other at a constant pitch. The length direction of the groove Gb is inclined clockwise with respect to the X direction. In the example shown in FIG. 5, the groove Gb is curved in an arc shape, but the groove Gb may not be curved. As a material of the diffractive structure forming layer 223a, for example, those described above for the diffractive structure forming layer 223a can be used.

  The reflective layer 224b is interposed between the cover body 21 and the diffractive structure forming layer 223b. The reflective layer 224b is formed on the diffraction structure forming layer 223b. The reflective layer 224b covers at least part of the surface of the diffraction structure forming layer 223b where the relief structure is provided.

  The reflective layer 224b is light transmissive. As the reflective layer 224b, for example, the transparent reflective layer described above for the reflective layer 224a can be used.

  The resin layer 225b is formed on the reflective layer 224b. As a material of the resin layer 225b, for example, those described above for the resin layer 225a can be used. The resin layer 225b can be omitted.

  The protective layer 227b is interposed between the cover body 21 and the diffractive structure forming layer 223b. As a material of the protective layer 227b, for example, those described above for the protective layer 227a can be used. The protective layer 227b can be omitted.

  The resin layer 225 covers the cover body 21 and the image display layers 220a and 220b. The resin layer 225 has optical transparency and is typically transparent. The resin layer 225 is made of, for example, a thermoplastic resin. The resin layer 225 can be omitted.

  The protective layer 227 is provided on the resin layer 225. The protective layer 227 has optical transparency and is typically transparent. The protective layer 227 is made of a resin such as acrylic, polyethylene, or polyester.

  The image display layers 220a and 220b are designed to display parallax images having substantially the same brightness. For example, the brightness of the parallax image displayed by the image display layer 220a and the parallax image displayed by the image display layer 220b can be made substantially equal by appropriately setting the reflectance or transmittance of the reflection layers 224a and 224b. .

  As described above, the image display body 22 displays a stereoscopic image as the image I1b. That is, this image display body 22 shows a complicated visual effect.

  Further, when the configuration described above with respect to the image display body 22 is employed, high resolution can be achieved relatively easily. This will be described with reference to FIGS. 2, 3, 6 and 7. FIG.

  FIG. 6 is an enlarged plan view showing a part of the personal authentication medium according to the comparative example. FIG. 7 is a cross-sectional view taken along line VII-VII of the personal authentication medium shown in FIG.

  In the structure shown in FIGS. 6 and 7, the image display layer 220a and the image display layer 220b are juxtaposed without stacking the image display layers 220a and 220b. Specifically, the columns for the image display layer 220a and the columns for the image display layer 220b are alternately arranged in the X direction, and the image display layer 220a and the image display layer 220b are respectively aligned with the column for the image display layer 220a and the column for the image display layer 220a. They are arranged in a row for the image display layer 220b.

  When this structure is adopted, in order to achieve a high resolution, the dot-like portions constituting each of the image display layers 220a and 220b must be remarkably reduced. Such an image display 22 is particularly difficult to manufacture in the process of recording an image on demand. Therefore, it is difficult to achieve high resolution.

  On the other hand, when the structure shown in FIGS. 2 and 3 is adopted, a high resolution can be achieved without excessively reducing the dot-shaped portions constituting each of the image display layers 220a and 220b. it can. For example, assuming that the dimensions of the image display layers 220a and 220b are the same between the structure shown in FIGS. 2 and 3 and the structure shown in FIGS. 6 and 7, when the structure shown in FIGS. Double the resolution can be achieved when the structure shown in FIGS. 6 and 7 is adopted. Therefore, when the structure shown in FIGS. 2 and 3 is adopted, the above-described problem does not occur, and high resolution can be achieved relatively easily. That is, an image can be displayed with high image quality.

Next, a method for manufacturing the personal authentication medium 100 will be described with reference to FIG.
FIG. 8 is a cross-sectional view schematically showing an example of a secondary transfer foil that can be used for manufacturing the personal authentication medium shown in FIGS. 1 to 3.

  The transfer foil 202 shown in FIG. 8 is a transfer ribbon, for example. The transfer foil 202 includes a support 226 and a transfer material layer 22 ′ that is releasably supported by the support 226.

  The support body 226 is a resin film or a sheet, for example. The support 226 is made of a material having excellent heat resistance such as polyethylene terephthalate. On the main surface supporting the transfer material layer 22 ′ of the support 226, a release layer containing, for example, a fluororesin or a silicone resin may be provided.

  The transfer material layer 22 'includes a peeling protection layer 227', a resin layer 225 ', and image display layers 220a and 220b.

  The peeling protective layer 227 'serves to stabilize peeling of the transfer agent layer 22' from the support 226 and to protect the image display layers 220a and 220b from damage. A part or all of the peeling protective layer 227 'is used as the protective layer 227 shown in FIG. In the case where the resin layer 225 'has a function of a release layer, the release protective layer 227' can be omitted.

  The resin layer 225 'is formed on the release protective layer 227'. The resin layer 225 'plays a role of giving sufficient strength to the transfer agent layer 22'. As a material of the resin layer 225 ', for example, a thermosetting resin, a photocurable resin, and a thermoplastic resin can be used. When a thermosetting resin is used, a part or all of the resin layer 225 'can be used as the resin layer 225 shown in FIG.

  On the resin layer 225 ', an image display layer 220b and an image display layer 220a are laminated in this order. Each of the image display layers 220a and 220b is, for example, a part of a transfer material layer that is releasably supported by a transfer foil support separately prepared on the resin layer 225 ′ using a thermal head. It is formed by thermal transfer to

  Since the image display layers 220a and 220b thus obtained are formed by thermal transfer using a thermal head, typically, the image display layers 220a and 220b are composed of a plurality of dot-like portions as shown in FIGS. Each center of the dot-like portion constituting the image display layer 220a is located on a lattice point of a virtual planar lattice. Similarly, each center of the dot-like portion constituting the image display layer 220b is located on a lattice point of a virtual planar lattice.

  In the arrangement shown in FIG. 2, the previous planar lattice is a square lattice, but the planar lattice may be other lattices such as a triangular lattice and a rectangular lattice. Further, in FIG. 2, a virtual planar lattice in which the center of the dot-shaped portion constituting the image display layer 220a is positioned on the lattice point, and the center of the dot-shaped portion constituting the image display layer 220b. Are the same as the virtual planar grid located on the grid points, but they may be different. For example, the planar grids may have their grid points spaced from each other.

  In FIG. 2, for each of the image display layers 220 a and 220 b, adjacent dot-like portions are arranged so that their outlines touch at one point. That is, the diameter of each dot-like part is equal to the minimum center distance of the dot-like parts. Adjacent dot-like portions may be separated from each other. That is, the diameter of each dot-shaped portion may be smaller than the minimum center-to-center distance of the dot-shaped portion. Alternatively, the adjacent dot-like portions may be arranged so as to partially overlap. That is, the diameter of each dot-shaped portion may be larger than the minimum center-to-center distance of the dot-shaped portion.

  The diameter of the dot-shaped portion or the minimum center-to-center distance of the dot-shaped portion is, for example, in the range of 0.085 to 0.508 mm (about 300 to about 50 dots per inch). When displaying face images on the image display layers 220a and 220b, the diameter of the dot-shaped portion or the minimum center-to-center distance of the dot-shaped portion is, for example, 0.085 to 0.169 mm (about 300 to about 150 dots per inch). Within the range of When this dimension is increased, it becomes difficult to display high-definition images on the image display layers 220a and 220b. When this dimension is reduced, the reproducibility of the pattern shape of the image display layers 220a and 220b is lowered.

  An image display layer (not shown) for displaying the images I1a and I2 shown in FIG. 1 is further formed on the resin layer 225 'or between the peeling protective layer 227' and the resin layer 225 '. When the image display layer is formed on the resin layer 225 ′, the image display layer may be formed before the image display layer 220b is formed on the resin layer 225 ′, or the image display layer may be displayed on the resin layer 225 ′. It may be formed after forming the layer 220b and before forming the image display layer 220a, or after forming the image display layer 220a on the resin layer 225 ′.

  When the image display layer for displaying the images I1a and I2 shown in FIG. 1 is formed by a thermal transfer method, a sublimation transfer method may be employed, a melt transfer method may be employed, or both of them may be employed. Good. The images I1a and I2 may be monochrome images or color images. In the latter case, the image display layer that displays the images I1a and I2 is formed, for example, by using one or more ink ribbons to form, for example, four colored layers of yellow, magenta, cyan, and black, or It is obtained by forming colored layers of three colors of red, green and blue.

  A layer (not shown) for displaying the image I3 shown in FIG. 1 may be further formed on the resin layer 225 'or between the release protective layer 227' and the resin layer 225 '. When the layer for displaying the image I3 is formed on the resin layer 225 ′, this layer may be formed before the image display layer 220b is formed on the resin layer 225 ′, or the image display on the resin layer 225 ′. It may be formed after forming the layer 220b and before forming the image display layer 220a, or after forming the image display layer 220a on the resin layer 225 ′. Alternatively, the layer for displaying the image I3 may be formed on the cover body 21 instead of being formed on the resin layer 225 'or between the peeling protection layer 227' and the resin layer 225 '. The layer for displaying the image I3 can be formed, for example, by the same method as described for the image display layer for displaying the images I1a and I2.

  Next, a portion of the transfer material layer 22 ′ formed on the support 226 to be used as the image display body 22 is thermally transferred from the support 226 onto the cover body 21 shown in FIG. 3. For this thermal transfer, for example, a hot stamp is used. Instead of thermal transfer using a hot stamp, thermal transfer using a thermal roll or a thermal head may be performed. The image display body 22 is pasted on the cover body 21 as described above.

  A layer for displaying the image I3 may be formed on the cover body 21 as described above. Further, an adhesive anchor layer may be formed on the cover body 21 in order to increase the adhesive strength.

  When it is difficult to bond the image display body 22 to the cover body 21 with high adhesive strength, a portion of the transfer material layer 22 ′ used as the image display body 22 is transferred onto the cover body 21 through the adhesive layer. Thermal transfer may be performed. For example, an adhesive ribbon may be used. If this is used, the adhesive strength between the image display body 22 and the cover body 21 can be increased. According to this method, a structure in which an adhesive layer is interposed between the image display body 22 and the cover body 21 is obtained.

  When it is difficult to bond the image display body 22 to the cover body 21 with high adhesive strength, and when the image display layer for displaying the images I1a and I2 is formed after the formation of the image display layers 220a and 220b, an adhesive ribbon You may use the ink ribbon which added the function of. This eliminates the need to use an adhesive ribbon separately from the ink ribbon.

  The layers for displaying the images I1a, I2 and I3 shown in FIG. 1 may be provided on the protective layer 227 after the image display 22 is bonded to the cover body 21.

  After the image display body 22 is thermally transferred onto the cover body 21 as described above, necessary steps are appropriately performed. In this way, the personal authentication medium 100 described with reference to FIGS. 1 to 5 is obtained.

  In this method, the image display layers 220a and 220b are formed by thermal transfer using a thermal head. The fineness that can be achieved when using a thermal head is higher than the fineness that can be achieved when printing pearl pigments.

  Further, when the image display layers 220a and 220b are directly formed on the cover body 21 by thermal transfer using a thermal head, it is difficult to achieve high image quality due to the surface roughness of the cover body 21 and the like. In contrast, in the above-described method, the image display layers 220a and 220b are not directly formed on the cover body 21. That is, in this method, first, it is formed on the peeling protection layer 227 ′, and then transferred onto the cover body 21 together with the peeling protection layer 227 ′. Therefore, the surface roughness of the cover body 21 does not have a great influence on the image quality.

  Therefore, according to this method, it is possible to display images with excellent image quality on the image display layers 220a and 220b.

  The image display 22 displays a part of personal information using a hologram and / or a diffraction grating. It is extremely difficult to tamper with personal information displayed by the hologram and / or diffraction grating, particularly biological information.

In this method, the image display body 22 is supported on the cover body 21 by thermal transfer. Such an image display body 22 is easily destroyed when it is peeled off from the cover body 21.
Therefore, the personal authentication medium 100 is difficult to falsify.

Various modifications can be made to the image display body 22 described above.
FIG. 9 is an enlarged plan view showing a part of a personal authentication medium according to a modification. FIG. 10 is an enlarged cross-sectional view of a part of a personal authentication medium according to another modification.

  In the image display body 22 described with reference to FIGS. 1 to 5, the parallax images displayed by the image display layer 220 a are the first and second portions that should display the same color, and the image display layer 220 b When included in the inside and outside of the outline of the parallax image to be displayed, the brightness of the first portion is affected by the image display layer 220b. That is, the reflective layer 224b prevents the illumination light from entering and exiting the portion of the image display layer 220a located behind the image display layer 220b. Therefore, the first part may appear darker than the second part.

  In the structure shown in FIG. 9, among the dot-shaped portions of the image display layer 220a, the surface density of the dot-shaped portion of the image display layer 220b is positioned in front, and the dot-shaped portion of the image display layer 220b is positioned in front. It is large compared to the surface density of those not. Here, among the dot-shaped portions of the image display layer 220a, the area where the dot-shaped portion of the image display layer 220b is located in front is the area where the dot-shaped portion of the image display layer 220b is not located ahead. Big compared to. When this structure is adopted, by appropriately setting the ratio, it is possible to prevent portions that should display the same color from appearing to have different brightness. That is, this configuration is advantageous in reducing the influence of the reflective layer 224b on the image quality of the image displayed by the image display layer 220a.

  Further, in the structure shown in FIG. 10, the luminance adjustment layer 220c is arranged on the dot-like portion of the image display layer 220a where the dot-like portion of the image display layer 220b is not located in front.

  The brightness adjustment layer 220c is the same as the image display layer 220b except that the diffraction structure is not provided. Specifically, the brightness adjustment layer 220c includes a base layer 223c, a reflective layer 224c, a resin layer 225c, and a protective layer 227c.

  For example, the base layer 223c is made of the same material as described above for the diffraction structure forming layer 223a. Typically, the surface of the base layer 223c on the reflective layer 224c side is flat.

  The reflective layer 224c covers one main surface of the base layer 223c. The reflective layer 224c is light transmissive. As the reflective layer 224c, for example, the transparent reflective layer described above for the reflective layer 224a can be used.

  The resin layer 225c is formed on the reflective layer 224c. As the resin layer 225c, as the material of the resin layer 225c, for example, those described above for the resin layer 225a can be used. The resin layer 225c can be omitted.

  The protective layer 227c is interposed between the cover body 21 and the base layer 223c. As the material of the protective layer 227c, for example, the materials described above for the protective layer 227a can be used. The protective layer 227c can be omitted.

  When the structure shown in FIG. 10 is adopted, the transmittance of the luminance adjustment layer 220c and the transmittance of the image display layer 220b are substantially matched to prevent portions that should display the same color from appearing to have different brightness. can do. That is, this configuration is also advantageous in reducing the influence of the reflective layer 224b on the image quality of the image displayed by the image display layer 220a.

  Here, a configuration in which a parallax image for the right eye is displayed on the image display layer 220a and a parallax image for the left eye is displayed on the image display layer 220b is adopted, but the parallax image for the left eye is displayed on the image display layer 220a. A configuration may be adopted in which a right-eye parallax image is displayed on the image display layer 220b. Here, the configuration in which the image display layer 220a and the image display layer 220b are provided to display two parallax images is employed, but three or more image display layers that display different parallax images may be provided. . That is, a configuration may be adopted in which the appearance of the stereoscopic image changes as if the subject is actually observed by changing the observation angle. In this case, all of the image display layers may be overlapped or only a part may be overlapped.

  Instead of displaying monochrome images on the image display layers 220a and 220b, color images may be displayed on them. For example, each of the image display layers 220a and 220b may be composed of three types of dot-shaped portions whose display colors are red, green, and blue. In this case, the image display layers 220a and 220b may be arranged so that dot-like portions having the same display color overlap, or may be arranged so that dot-like portions having different display colors overlap.

  At the position where the image display layers 220a and 220b overlap, the image display layer 220b diffracts part of the incident light. Therefore, at the position where the image display layers 220a and 220b overlap, the light having the same wavelength as that of the previous diffracted light is lower in the image display layer 220a than the position where the image display layers 220a and 220b do not overlap. Incident. Therefore, when the image display layers 220a and 220b are arranged so that dot portions having the same display color overlap, the image display layer 220b affects the brightness of the image displayed by the image display layer 220a.

  When the image display layers 220a and 220b are arranged so that the dot-like portions having different display colors overlap with each other, the image display layer 220a is diffracted by the light diffracted by the image display layer 220b at the position where the image display layers 220a and 220b overlap. Uses light of different wavelengths for display. Therefore, when this configuration is adopted, the influence of the image display layer 220b on the brightness of the image displayed by the image display layer 220a can be reduced.

  The personal authentication medium 100 as a passport has been exemplified above, but the technique described above for the personal authentication medium 100 can also be applied to other personal authentication media. For example, this technology can be applied to various cards such as a visa and an ID card.

  The material of the base material to which the image display body 22 is attached may be other than paper. For example, the base material to which the image display body 22 is attached may be a plastic substrate, a metal substrate, a ceramic substrate, or a glass substrate.

  The image to be displayed on the image display layer 220a may include other biological information in addition to the face image, or may include other biological information instead of the face image. The image displayed on the image display layer 220a may include at least one of non-biological personal information and non-personal information in addition to biometric information, and at least non-biological personal information and non-personal information instead of the biometric information. One may be included.

  Instead of displaying stereoscopic images on the image display layers 220a and 220b, different planar images may be displayed on them. In other words, the previous image display 22 may employ a configuration in which the display image is switched according to the observation angle.

  DESCRIPTION OF SYMBOLS 1 ... Signature, 2 ... Cover, 11 ... Paper piece, 21 ... Cover body, 22 ... Image display body, 22 '... Transfer material layer, 100 ... Personal authentication medium, 202 ... Transfer foil, 220a ... Image display layer, 220b ... Image display layer, 220c ... brightness adjustment layer, 223a ... diffraction structure formation layer, 223b ... diffraction structure formation layer, 223c ... base layer, 224a ... reflection layer, 224b ... reflection layer, 224c ... reflection layer, 225 ... resin layer, 225a ... resin layer, 225b ... resin layer, 225c ... resin layer, 226 ... support, 227 ... protective layer, 227 '... peeling protective layer, 227a ... protective layer, 227b ... protective layer, 227c ... protective layer, Ga ... groove, Gb ... groove, I1a ... image, I1b ... image, I2 ... image, I3 ... image.

Claims (9)

The first image is displayed as a diffraction image when observed from a first direction under a specific illumination condition, and the first image is displayed when observed from a second direction different from the first direction under the illumination condition. A relief-type first diffractive structure that does not display one image as a diffraction image or displays the first image as a darker diffraction image as compared to the case where the first image is observed from the first direction;
When observed from the second direction under the illumination conditions, a second image different from the first image is displayed as a diffraction image, and when observed from the first direction under the illumination conditions A relief-type second diffractive structure that does not display the second image as a diffracted image or displays the second image as a diffracted image darker than when observed from the second direction, The diffractive structure has an optical transparency, and is an image display body that is at least partially facing the first diffractive structure in front of the first diffractive structure. A first image display layer comprising a first reflective layer provided with the first diffractive structure on one main surface, and having a shape corresponding to the first image;
The second diffractive structure is provided on one main surface, includes a second reflective layer having optical transparency, has a shape corresponding to the second image, and includes the first image display layer and The image display body according to claim 1, further comprising a second image display layer at least partially overlapping.   The first image display layer is composed of a plurality of first dot-like portions whose centers are located on lattice points of a virtual planar lattice, and each center of the second image display layer is virtual. A plurality of second dot-like portions located on lattice points of a typical planar lattice, and the plurality of first dot-like portions and the plurality of second dot-like portions overlap at least partially. The image display body according to claim 2.   The first image includes first and second parts having the same display color on the inner side and the outer side of the outline of the second image, respectively, and in the region corresponding to the first part, the second part includes The image display body according to claim 3, wherein an area density of the first dot-like portion is larger than that of a corresponding region.   The image display body of any one of Claims 1 thru | or 4 which displays a stereo image by the said 1st and 2nd image as a diffraction image.   The image display body according to claim 5, wherein the stereoscopic image includes personal information.   The image display body according to claim 6, wherein the personal information includes a face image.   A transfer foil comprising the image display body according to any one of claims 1 to 7 and a support body that releasably supports the image display body. The image display body according to any one of claims 1 to 7,
A personal authentication medium comprising a base material supporting the image display body.

Images