JP6932975B2 - Personal authentication medium - Google Patents

Description

The present invention relates to a personal authentication medium for authenticating a specific individual.

As a personal authentication medium such as a card or a passport, a personal authentication medium including a laser coloring layer and a hologram layer located above the laser coloring layer is known. The laser coloring layer has a property of turning black by absorbing a laser beam having a specific wavelength. For example, a face image of an individual is written in the laser coloring layer as information belonging to a specific individual. The hologram layer is configured to display an image having a predetermined color due to a change in the refractive index of the hologram layer and an uneven structure (see, for example, Patent Document 1).

International Publication No. 2012/050223

In the above-mentioned personal authentication medium, the hologram layer located above the laser coloring layer enhances the effect of suppressing forgery of the personal authentication medium, but there is a demand for a personal authentication medium having a higher effect of suppressing forgery. There is.

It should be noted that such a problem is not limited to the personal authentication medium in which the information belonging to the individual is written in the laser coloring layer, but also in the personal authentication medium in which the information belonging to the individual is written in the layer other than the laser coloring layer by, for example, ink or toner. Is also common.
An object of the present invention is to provide a personal authentication medium capable of suppressing counterfeiting.

The personal authentication medium for solving the above problems includes an image display layer including a display unit for displaying the first image element and including a front surface and a back surface, and the display unit in the thickness direction of the image display layer. A surface diffracting portion including a surface diffracting lattice that is located on the surface so as to overlap and emits diffracted light as reflected light to form a second image element by the diffracted light, and the front diffracting portion and the back surface diffracting portion. The back surface diffracting portion located on the back surface so as to sandwich the display unit between the two and spread outward from the display unit, and a region overlapping the display unit and a region not overlapping the display unit. In addition, the back surface diffracting portion including a back surface diffraction lattice that emits diffracted light as reflected light and forms a third image element by the diffracted light is provided. In the thickness direction of the image display layer, the front surface diffraction portion has transparency at a portion where the display portion and the back surface diffraction grating overlap, and the portion of the image display layer other than the display portion is , The side that has transparency at the portion overlapping the back surface diffraction grating and the front surface diffraction portion is located with respect to the image display layer is the observation side of the personal authentication medium, and the personal authentication medium is observed from the observation side. Then, the first image element, the second image element, and the third image element form one identification image including information for identifying the owner of the personal authentication medium.

In a configuration in which the personal authentication medium includes a surface diffracting portion located on the surface of the image display layer, the personal authentication medium is forged by peeling the surface diffracting portion from the genuine image display layer and attaching it to a fake image display layer. .. Further, with the surface diffraction portion positioned on the image display layer, only the portion of the image display layer on which the display portion is formed is removed from the side opposite to the surface diffraction portion with respect to the image display layer, and the surface diffraction portion is removed. By embedding a fake display part in this removed part, the personal authentication medium may be forged.

In this respect, in the above configuration, since the diffraction portions are located on the front surface and the back surface of the image display layer, it is difficult to remove only the portion of the image display layer on which the display portion is formed. Furthermore, since the first image element, the second image element, and the third image element form one specific image, the front side diffraction part and the back side diffraction part must be aligned with each other with respect to the fake image display layer. It is difficult for a fake personal authentication medium to display the same image as the specific image displayed by the genuine personal authentication medium. Therefore, according to such a personal authentication medium, forgery of the personal authentication medium can be suppressed.

In the personal authentication medium, the image display layer has a characteristic of developing color by irradiation with a laser beam, the display unit is a portion colored in the image display layer by irradiation with the laser beam, and the first image element is , It is preferable to include the face image of the owner.

According to the above configuration, since the face image is sandwiched by the pair of diffractive portions in the thickness direction of the image display layer, it is difficult to replace the face image of the personal authentication medium with another face image. Therefore, forgery of the personal authentication medium can be suppressed.

In the personal authentication medium, the front surface image portion is located on the front surface different from the portion where the surface diffraction portion is located, and the front surface image portion including at least one character is located, and the back surface diffraction portion is located on the back surface. The observation side is further provided with a back surface image portion that is different from the portion and is located at a portion that does not overlap with the front surface image portion in the thickness direction of the image display layer and includes at least one character. When the personal authentication medium is observed, it is preferable that the front surface image portion and the back surface image portion are included in one identification character string including information for identifying the owner.

According to the above configuration, in order to form a fake specific character string so as to resemble a genuine specific character string, it is only necessary to align the positions of the characters forming the specific character string in the plan view facing the surface. Therefore, it is necessary to align each character in the thickness direction of the image display layer. Therefore, it is more difficult to forge the specific character string than the configuration in which all the characters forming the specific character string are located on the same surface, and it is possible to suppress the forgery of the personal authentication medium.

In the personal authentication medium, the display unit is the first display unit, and the image display layer has a characteristic of developing color by irradiation with a laser beam, and is a portion colored by the image display layer by irradiation with the laser beam. In addition, in the thickness direction of the image display layer, the front surface image portion further includes a second display portion that does not overlap with both the front surface image portion and the back surface image portion and includes at least one character. And the back surface image unit are formed of ink, and when the personal authentication medium is observed from the observation side, the front surface image unit, the back surface image unit, and the second display unit form the specific character string. May be included in.

According to the above configuration, since one specific character string contains characters formed by different forming materials, in order to forge the specific character string possessed by the personal authentication medium, the specific character strings are different from each other. It is necessary to include the letters formed by the forming material. Therefore, as compared with the configuration in which the specific character string is formed by a single forming material, the forgery of the personal authentication medium can be suppressed by the amount of man-hours and time required for forgery of the specific character string.

In the personal authentication medium, a surface that is located in a portion of the surface different from the portion where the surface diffraction portion is located and is a part of one identification character included in the information for identifying the owner. The front surface image portion including the element is different from the portion of the back surface where the back surface diffraction portion is located, and is located at a portion that does not overlap with the front surface image portion in the thickness direction of the image display layer. Further, a back image portion including a back surface element which is another part of the specific character is further provided, and when the personal authentication medium is observed from the observation side, the front surface element and the back surface element are The specific character may be formed.

According to the above configuration, in order to form a fake identification character so as to resemble a genuine identification character, not only the front surface element and the back surface element are aligned in a plan view facing the front surface, but also the image display layer. It is necessary to align each element in the thickness direction of. Therefore, it is more difficult to forge the specific character than the configuration in which all the elements forming the specific character are located on the same surface, and it is possible to suppress the forgery of the personal authentication medium.

In the personal authentication medium, in the specific characters, the front surface element and the back surface element may be portions that are connected to each other when the personal authentication medium is observed from the observation side.

According to the above configuration, if the position of the back surface element is not highly accurate with respect to the position of the front surface element in a plan view facing the front surface, a gap may be formed between the front surface element and the back surface element, or a part of the back surface element. Is overlapped with a part of the surface element, so that the shape of the specific character deviates from the desired shape. Therefore, it is possible to determine whether or not the specific character is a forged character based on the shape of the specific character.

In the personal authentication medium, the surface diffraction grating includes the surface diffraction grating and has a transmissive transmission portion, and the surface diffraction grating is located outside the surface diffraction grating in a plan view facing the surface. The back surface diffraction grating includes the third image element inside, and includes a concealing portion that constitutes an edge and conceals an image formed by the lower layer of the surface diffraction portion. The basic image as a base, which protrudes from the transmission portion and has a size equal to or smaller than the edge in a plan view facing the surface, may be formed.

According to the above configuration, the observer of the personal authentication medium can visually recognize only the third image element which is a part of the basic image formed by the backside diffraction grating. Therefore, when the personal authentication medium is forged, there is a high possibility that only the diffraction grating that forms only the third image element that can be visually recognized at the time of observation is forged. Therefore, it is a genuine personal authentication medium depending on whether or not the back surface diffracting portion can form a basic image larger than the third image element in a plan view facing the front surface of the personal authentication medium. It is also possible to determine whether or not.

According to the present invention, forgery of the personal authentication medium can be suppressed.

FIG. 3 is a plan view showing a plan structure in a plan view facing the surface of the personal authentication medium in one embodiment embodying the personal authentication medium. FIG. 5 is a cross-sectional view showing a cross-sectional structure of a personal authentication medium along the line I-I of FIG. A partially enlarged cross-sectional view showing a partially cross-sectional structure of a personal authentication medium in an enlarged manner. A partially enlarged cross-sectional view showing a partially cross-sectional structure of a personal authentication medium in an enlarged manner. An exploded perspective view showing a personal authentication medium decomposed into a plurality of layers. FIG. 5 is a cross-sectional view showing a cross-sectional structure of a transfer foil used for forming a surface diffraction portion included in a personal authentication medium. FIG. 3 is a process chart showing a process of transferring a front diffraction portion and a back diffraction portion to an image display layer in a method of manufacturing a personal authentication medium. The process chart which shows the process of printing on each layer. The process chart which shows the process of irradiating the image display layer with a laser beam. The cross-sectional view which shows the cross-sectional structure in the modification of the personal authentication medium. An exploded perspective view showing a modified example of a personal authentication medium in which the personal authentication medium is decomposed into a plurality of layers.

An embodiment in which the personal authentication medium is embodied will be described with reference to FIGS. 1 to 9. Hereinafter, the configuration of the personal authentication medium, the manufacturing method of the personal authentication medium, the forming material of each part constituting the personal authentication medium, and the examples will be described in order.

[Structure of personal authentication medium]
The configuration of the personal authentication medium will be described with reference to FIGS. 1 to 5.
As shown in FIG. 1, the personal authentication medium 10 has a plate shape and includes a surface 10F as one of the surfaces constituting the personal authentication medium 10. In the plan view facing the surface 10F, the personal authentication medium 10 displays the identification image PIC, and the identification image PIC is composed of the first image element PIC1, the second image element PIC2, and the third image element PIC3. ing. That is, the first image element PIC1, the second image element PIC2, and the third image element PIC3 form one identification image PIC including information for identifying the owner of the personal authentication medium 10.

In a plan view facing the surface 10F, the personal authentication medium 10 displays the first character string CHA1, the second character string CHA2, the third character string CHA3, the fourth character string CHA4, and the fifth character string CHA5. The five character strings include a identification character string including information for identifying the owner of the personal authentication medium 10. Of the five character strings, the first character string CHA1, the second character string CHA2, and the third character string CHA3 are examples of specific character strings, respectively. The first character string CHA1 includes a personal number unique to the owner of the personal authentication medium 10 as identification information, the second character string CHA2 includes the name of the owner as identification information, and the third character string CHA3 Includes the owner's nationality as specific information.

The personal number, name, and nationality are examples of information included in the specific character string, and the information included in the specific character string is, for example, the date of birth of the owner, the gender of the owner, and possession. It may be the signature of a person. Further, the characters constituting the specific character string are not limited to alphabets and numbers, but may be kanji, hiragana, katakana, or the like, or may be characters peculiar to languages other than Japanese.

The fourth character string CHA4 and the fifth character string CHA5 are character strings other than the specific character string, and the fourth character string CHA4 includes, for example, the expiration date of the validity period in the personal authentication medium 10 as information, and the fifth character. The column CHA5 includes the name of the personal authentication medium 10 as information. The personal authentication medium 10 may be configured to display a character string including information other than these as a character string other than the specific character string.

FIG. 2 shows a cross-sectional structure of the personal authentication medium 10 along the line I-I of FIG. In FIG. 2, for convenience of illustration, the thickness of each layer constituting the personal authentication medium 10 and the size of each part are exaggerated.

As shown in FIG. 2, the personal authentication medium 10 includes an image display layer 11, a front surface diffraction unit 12, and a back surface diffraction unit 13. The image display layer 11 includes a display unit 11a for displaying the first image element PIC1 described above, and includes a front surface 11F and a back surface 11R. The surface diffraction unit 12 is located on the surface 11F of the image display layer 11 so as to overlap the display unit 11a in the thickness direction of the image display layer 11. The back surface diffraction unit 13 is located on the back surface 11R of the image display layer 11 so as to sandwich the display unit 11a between the front surface diffraction unit 12 and the back surface diffraction unit 13 and to spread outward from the display unit 11a. The back surface diffraction unit 13 includes a region that overlaps the display unit 11a and a region that does not overlap the display unit 11a.

The personal authentication medium 10 further includes a front surface image unit 21 and a back surface image unit 22. The surface image unit 21 is located on the surface 11F of the image display layer 11 at a portion different from the portion where the surface diffraction unit 12 is located. The surface image unit 21 contains at least one character. The back surface image unit 22 is a portion of the back surface 11R of the image display layer 11 that is different from the portion where the back surface diffraction unit 13 is located, and overlaps with the front surface image unit 21 in the thickness direction of the image display layer 11. It is located in a part that does not become. The back surface image unit 22 contains at least one character.

The side where the surface diffraction unit 12 is located with respect to the image display layer 11 is the observation side of the personal authentication medium 10. When the personal authentication medium 10 is observed from the observing side, the front surface image unit 21 and the back surface image unit 22 are included in one identification character string including information for identifying the owner. Each of the characters included in the front image unit 21 and the characters included in the back image unit 22 is included in any of the above-mentioned third character string CHA3, fourth character string CHA4, and fifth character string CHA5. ..

The personal authentication medium 10 further includes a first base material 14, a second base material 15, and a third base material 16. In the personal authentication medium 10, the first base material 14, the second base material 15, the image display layer 11, and the third base material 16 are stacked in the order described. The back surface diffraction unit 13 is located between the second base material 15 and the image display layer 11, and the front surface diffraction unit 12 is located between the image display layer 11 and the third base material 16.

The first base material 14 preferably has sufficient mechanical strength to support the second base material 15, the image display layer 11, and the third base material 16 stacked on the first base material 14. .. The first base material 14 has a predetermined color such as white and does not transmit light, but may transmit light. Of the first base material 14, the surface in contact with the second base material 15 is the surface 14F.

The base material image portion 23 is located on the surface 14F of the first base material 14. The base material image unit 23, like each of the front surface image unit 21 and the back surface image unit 22, contains at least one character. The character included in the base material image unit 23 may be a character included in any of the specific character strings, or may be a character included in a character string other than the specific character string.

The second base material 15 covers the entire back surface diffraction unit 13 located on the back surface 11R of the image display layer 11 and the entire back surface image unit 22. The second base material 15 has light transmission property, and the second base material 15 is configured so that the base material image portion 23 can be visually recognized by an observer in a plan view facing the surface 10F of the personal authentication medium 10. There is.

The third base material 16 covers the entire surface diffraction unit 12 located on the surface 11F of the image display layer 11 and the entire surface image unit 21. As a result, the third base material 16 functions as a protective layer that prevents the surface diffraction unit 12 and the surface image unit 21 from being chemically or physically damaged. The third base material 16 has light transmission property, and in a plan view facing the front surface 10F of the personal authentication medium 10, the light emitted from the front diffraction unit 12, the light emitted from the back surface diffraction unit 13, and the surface image unit. The third base material 16 is configured so that the 21, back surface image portion 22, and the base material image portion 23 can be visually recognized by the observer.

The surface diffraction unit 12 includes a transmission unit 12a and a concealing unit 12b, and the concealing unit 12b surrounds the transmission unit 12a in a plan view facing the surface 10F of the personal authentication medium 10. A more detailed configuration of the surface diffractometer 12 will be described below with reference to FIG.

FIG. 3 is an enlarged part of the cross-sectional structure of the personal authentication medium 10 shown in FIG. 2, which is the cross-sectional structure of the front diffraction unit 12, the cross-sectional structure of the back surface diffraction unit 13, and the cross-sectional structure of the image display layer 11. Shown.

As shown in FIG. 3, the surface diffraction unit 12 includes a diffraction layer 31 and an adhesive layer 32. The diffraction layer 31 includes a transmission portion 31a and a concealing portion 31b, and the concealing portion 31b constitutes the above-mentioned concealing portion 12b. The diffraction layer 31 includes a surface diffraction grating 31c that emits diffracted light as reflected light to form the second image element PIC2 described above by the diffracted light. The transmission portion 31a includes a surface diffraction grating 31c and has transparency. In a plan view facing the surface 11F of the image display layer 11, the concealing portion 31b is located outside the transmission portion 31a to form an edge of the surface diffraction portion 12, and is an image formed by the lower layer of the surface diffraction portion 12. To hide.

In the diffraction layer 31, the surface in contact with the adhesive layer 32 is the back surface 31R, and the front surface diffraction grating 31c is an uneven surface included in a part of the back surface 31R of the diffraction layer 31. Although the front diffraction grating 31c is located only in a part of the back surface 31R of the diffraction layer 31, it may be located in the entire back surface 31R.

The surface diffraction grating 31c diffracts toward the viewpoint when the observer's viewpoint is located at a predetermined fixed point with respect to the surface 10F of the personal authentication medium 10 on the side where the surface diffraction unit 12 is located with respect to the image display layer 11. Emit light. In the surface diffraction grating 31c, the lattice pattern, which is a groove extending along a predetermined direction, is repeated at predetermined intervals along a direction orthogonal to the direction in which the lattice pattern extends. The direction in which the grid pattern is repeated is set in the direction in which the diffracted light is emitted to the fixed point described above.

The number of grooves per unit length is the spatial frequency of the surface diffraction grating 31c. The spatial frequency may be constant throughout the surface diffraction grating 31c, or the surface diffraction grating 31c may include a plurality of portions having different spatial frequencies from each other.

In a plan view facing the surface 11F of the image display layer 11, the concealing portion 31b surrounds the transmissive portion 31a. The concealing unit 31b conceals an image formed by each of the layers below the concealing unit 31b, that is, the image display layer 11, the back surface diffraction unit 13, the second base material 15, and the first base material 14. The concealing portion 31b may conceal the image formed by the lower layer of the concealing portion 31b by having a predetermined color, or the lower layer of the concealing portion 31b by reflecting most of the light incident on the concealing portion 31b. The image formed by may be hidden. Further, the concealing unit 31b may conceal the image formed by the lower layer of the concealing unit 31b by scattering the light incident on the concealing unit 31b.

The adhesive layer 32 has a function of adhering the diffraction layer 31 to the image display layer 11 and has light transmittance. In the surface diffraction section 12, the transmission section 31a of the diffraction layer 31 and the adhesive layer 32 form an example of the transmission section 12a of the surface diffraction section 12.

The back surface diffraction unit 13 includes a diffraction layer 41 and an adhesive layer 42. The diffraction layer 41 includes a back surface diffraction grating 41a, and the back surface diffraction grating 41a emits diffracted light as reflected light, and the diffracted light forms the third image element PIC3 described above. In the diffraction layer 41, the surface in contact with the adhesive layer 42 is the back surface 41R. The back surface diffraction grating 41a is located on the entire back surface 41R of the diffraction layer 41, in other words, the entire back surface 41R is an uneven surface. Although the back surface diffraction grating 41a is located on the entire back surface 41R, it may be located only on a part of the back surface 41R.

Further, the back surface diffraction grating 41a includes the third image element PIC3 inside, and forms a basic image which is the basis of the third image element PIC3. In a plan view facing the surface 11F of the image display layer 11, the basic image protrudes from the transmission portion 12a of the surface diffraction portion 12 and has a size equal to or smaller than the edge of the surface diffraction portion 12. In a plan view facing the front surface 11F of the image display layer 11, the back surface diffraction unit 13 has substantially the same size as the front surface diffraction unit 12, and the entire back surface diffraction unit 13 overlaps the front surface diffraction unit 12. Therefore, in the basic image formed by the back surface diffraction grating 41a in the plan view facing the surface 11F of the image display layer 11, the portion of the surface diffraction unit 12 that protrudes from the transmission portion 31a of the diffraction layer 31 is formed by the concealing portion 31b. It is hidden.

The backside diffraction grating 41a emits diffracted light toward the viewpoint when the observer's viewpoint is located at the fixed point described above. In the back surface diffraction grating 41a, the lattice pattern, which is a groove extending along a predetermined direction, is repeated at predetermined intervals along a direction orthogonal to the direction in which the lattice pattern extends. The direction in which the grid pattern is repeated is set in the direction in which the diffracted light is emitted to the fixed point described above.

In the back surface diffraction grating 41a, the spatial frequency may be constant in the entire back surface diffraction grating 41a, or the back surface diffraction grating 41a may include a plurality of portions having different spatial frequencies from each other.

The image display layer 11 has a characteristic of developing color by irradiation with a laser beam. The display unit 11a is a portion that is colored by the image display layer 11 by irradiation with a laser beam. The color-developing portion has, for example, black, but may have a color other than black. The display unit 11a is composed of a plurality of color-developing units, and each color-developing unit is exposed on the front surface 11F of the image display layer 11 and is more front surface than the back surface 11R of the image display layer 11 in the thickness direction of the image display layer 11. It extends to a position closer to the 11th floor. Each color-developing portion may be exposed on the back surface 11R of the image display layer 11 and may extend to a position closer to the back surface 11R than the front surface 11F of the image display layer 11 in the thickness direction of the image display layer 11. The image display layer 11 may be located on the entire thickness direction of the image display layer 11 so as to be exposed on both the front surface 11F and the back surface 11R.

When the personal authentication medium 10 is observed from the observing side, the front diffraction unit 12 has transparency at a portion where the display unit 11a and the back surface diffraction grating 41a overlap. More specifically, in a plan view facing the surface 11F of the image display layer 11, the transmission portion 31a in the diffraction layer 31 of the surface diffraction portion 12 has a size surrounding the display portion 11a, and the transmission portion 31a is personally authenticated. In the medium 10, it is located at a portion overlapping a part of the back surface diffraction grating 41a. Further, the portion of the image display layer 11 other than the display portion 11a has transparency at a portion overlapping the back surface diffraction grating 41a when the personal authentication medium 10 is observed from the observation side. More specifically, the image display layer 11 has transparency in the entire portion overlapping the back surface diffraction grating 41a, but may have light transmission in a portion overlapping the back surface diffraction grating 41a.

The front diffraction unit 12 and the back surface diffraction unit 13 may have an intermediate layer located between the layers of each diffraction unit. Further, in the back surface 31R of the diffraction layer 31 included in the surface diffraction unit 12, a transparent reflection layer may be located at least at a portion where the surface diffraction grating 31c is located. A transparent reflective layer may also be located on the back surface diffraction grating 41a of the diffraction layer 41 included in the back surface diffraction unit 13. According to the configuration in which each diffracting portion has a transparent reflective layer, the brightness of the reflective layer emitted from each diffracted light can be increased. As the material for forming the transparent reflective layer, for example, zinc sulfide (ZnS), titanium oxide (TiO ₂ ) and the like can be used.

FIG. 4 shows, among the cross-sectional structures of the personal authentication medium 10 shown in FIG. 2, the cross-sectional structure of the first base material 14, the cross-sectional structure of the second base material 15, the cross-sectional structure of the image display layer 11, and the third base material. A part of the cross-sectional structure of 16 is shown enlarged.

As shown in FIG. 4, the base material image unit 23 is located between the front surface 14F of the first base material 14 and the back surface 15R of the second base material 15. The back surface image unit 22 is located between the front surface 15F of the second base material 15 and the back surface 11R of the image display layer 11. The front surface image unit 21 is located between the front surface 11F of the image display layer 11 and the back surface 16R of the third base material 16. In the base material image unit 23, the amount of the first base material 14 and the second base material 15 that bite into the base material having low rigidity is larger than the amount that bites into the other base material. The same applies to both the front surface image unit 21 and the back surface image unit 22.

In the personal authentication medium 10, the front surface 16F of the third base material 16 is the front surface 10F of the personal authentication medium 10, and the back surface 14R of the first base material 14 is the back surface 10R of the personal authentication medium 10.

FIG. 5 is a perspective view showing the personal authentication medium 10 in three layers. In FIG. 5, for convenience of illustration, the front surface diffraction unit 12 and the front surface image unit 21 are shown as one layer together with the third base material 16, and the back surface image unit 22 is shown as one layer together with the image display layer 11, and the back surface diffraction is shown. The part 13 and the base material image part 23 are shown as one layer together with the first base material 14 and the second base material 15.

As shown in FIG. 5, the first image element PIC1 displayed by the image display layer 11 includes a face image of the owner of the personal authentication medium 10. The first image element PIC1 is an image of the upper body of the owner, but may be composed only of the face image of the owner. The entire first image element PIC1 is a portion colored by irradiation with a laser beam, and is a portion in the image display layer 11 having a lower transparency than a portion other than the first image element PIC1. Therefore, in the image formed by the back surface diffraction unit 13 which is the lower layer of the image display layer 11, the portion where the first image element PIC1 overlaps is not visible in the plan view facing the surface 10F of the personal authentication medium 10.

The entire portion of the first image element PIC1 surrounded by the contour of the first image element PIC1 does not have to be a portion colored by the irradiation of the laser beam, and at least the contour of the first image element PIC1 is formed by the irradiation of the laser beam. Any part may be a colored part.

Since the face image is sandwiched by the pair of diffracting portions in the thickness direction of the image display layer 11, that is, the thickness direction of the personal authentication medium 10, it is difficult to replace the face image of the personal authentication medium 10 with another face image. .. Therefore, forgery of the personal authentication medium 10 can be suppressed.

The second image element PIC2 is an image formed by the diffracted light emitted by the surface diffraction grating 31c as reflected light, and as described above, the viewpoint of the observer is positioned at a predetermined fixed point with respect to the surface 10F of the personal authentication medium 10. It is an image that is visually recognized by the observer when the image is displayed. The second image element PIC2 is located in a part having a frame shape surrounding the first image element PIC1 and a part having a frame shape in a plan view facing the surface 10F of the personal authentication medium 10, and is an owner. It is composed of a part having a shape indicating a national flag corresponding to the nationality of. As described above, the second image element PIC2 may include a identification image for identifying the owner of the personal authentication medium 10.

When the personal authentication medium 10 attempts to falsify the information contained in the identification image of the second image element PIC2 by including the identification image in the second image element PIC2 in addition to the first image element PIC1, the second image element PIC2 is not included. 2 The image element PIC2 also needs to be changed according to the content to be tampered with. Therefore, it becomes difficult to falsify the information contained in the second image element PIC2.

In a plan view facing the surface 10F of the personal authentication medium 10, the concealing portion 12b has a frame shape that surrounds the entire second image element PIC2 in the circumferential direction. In a plan view facing the surface 10F of the personal authentication medium 10, the portion of the surface diffraction portion 12 located inside the concealing portion 12b is the transmission portion 12a, which transmits the lower layer than the surface diffraction portion 12.

The third image element PIC3 is included in the basic image PICB extending outward from the edge of the third image element PIC3. The basic image PICB is an image formed by the diffracted light emitted by the back surface diffraction grating 41a as reflected light, and is an image visually recognized by the observer when the observer's viewpoint is located at the above-mentioned fixed point. Of the basic image PICB, the portion included inside the concealing portion 12b in the plan view facing the surface 10F of the personal authentication medium 10 is the third image element PIC3. The basic image PICB has a size that does not protrude from the concealing portion 12b in a plan view facing the surface 10F of the personal authentication medium 10.

Only the third image element PIC3, which is a part of the basic image PICB formed by the back surface diffraction grating 41a, is visible to the observer of the personal authentication medium 10. Therefore, when the personal authentication medium 10 is forged, there is a high possibility that only the diffraction grating that forms only the third image element PIC3 that can be visually recognized at the time of observation is forged. Therefore, in a plan view facing the front surface 10F of the personal authentication medium 10, whether or not the back surface diffraction unit 13 can form a basic image PICB larger than the third image element PIC3 is genuine. It is also possible to determine whether or not the personal authentication medium 10 is used.

As described above, in the personal authentication medium 10, since the diffraction portions are located on the front surface 11F and the back surface 11R of the image display layer 11, only the portion of the image display layer 11 on which the display portion 11a is formed can be removed. difficult. Further, since the first image element PIC1, the second image element PIC2, and the third image element PIC3 form one specific image PIC, the front diffraction unit 12 and the back surface diffraction unit 13 with respect to the fake image display layer If the positions are not aligned, it is difficult for the fake personal authentication medium to display the same image as the specific image PIC displayed by the genuine personal authentication medium 10. Therefore, according to such a personal authentication medium 10, forgery of the personal authentication medium 10 can be suppressed.

The first character string CHA1 is composed of a plurality of first characters 1C, and the plurality of first characters 1C are composed of "MDSSS79020887". The second character string CHA2 is composed of a plurality of second characters 2C, and the plurality of second characters 2C are composed of "TARO SUZUKI". The third character string CHA3 is composed of a plurality of third characters 3C, and the plurality of third characters 3C are composed of "JAPAN". The fourth character string CHA4 is composed of a plurality of fourth characters 4C, and the plurality of fourth characters 4C are composed of "29 APR 2020". The fifth character string CHA5 is composed of a plurality of fifth characters 5C, and the plurality of fifth characters 5C are composed of "PASSPORT CARD".

Of each character string, at least one character is shown with the third base material 16, at least one character is shown with the image display layer 11, and at least one character is shown with the second base material 15. .. That is, at least one character of each character string is included in the front surface image unit 21, at least one character is included in the back surface image unit 22, and at least one character is included in the base material image unit 23. There is.

More specifically, in the first character string CHA1, the second character string CHA2, and the third character string CHA3, which are specific character strings, the characters adjacent to each other are the front image unit 21, the back image unit 22, and the third character string CHA3. It is included in different image parts in the base material image part 23. Therefore, each image unit contains only a part of the information contained in the character string, and a single character string containing information unique to the owner of the personal authentication medium 10 is formed only when the three image units are stacked on each other. Will be done.

In the plurality of characters constituting each of the first character string CHA1, the second character string CHA2, and the third character string CHA3, the plurality of characters adjacent to each other are the front image portion 21, the back surface image portion 22, and the back surface image portion 22. , In the base material image unit 23, they may be included in the same image unit. Further, a plurality of characters constituting each of the first character string CHA1, the second character string CHA2, and the third character string CHA3 may be included in any of the front surface image unit 21 and the back surface image unit 22. , It may not be included in the base material image unit 23.

According to such a configuration, in order to form a fake specific character string so as to resemble a genuine specific character string, each character forming the specific character string in a plan view facing the surface 11F of the image display layer 11 It is necessary not only to align the positions of the characters but also to align the positions of the characters in the thickness direction of the personal authentication medium 10. Therefore, it is more difficult to forge the specific character string than the configuration in which all the characters forming the specific character string are located on the same surface, and it is possible to suppress the forgery of the personal authentication medium 10.

In the fourth character string CHA4, which is a character string other than the specific character string, a plurality of characters adjacent to each other are different from each other in the front surface image unit 21, the back surface image unit 22, and the base material image unit 23. It is composed of a part included in and a part included in the same image part. The fourth character string CHA4 may be composed of only a portion in which a plurality of characters adjacent to each other are included in different image portions, or may be composed of only a portion included in the same image portion.

In the fifth character string CHA5, which is a character string other than the specific character string, the characters adjacent to each other are the front image unit 21, the back surface image unit 22, and the base material image unit 23, as in the case of the above-mentioned specific character string. Among them, they are included in different image parts. Therefore, each image unit includes only a part of the information included in the character string, and a single character string including predetermined information is formed only when the three image units are stacked on each other. In the plurality of characters constituting the fifth character string CHA5, a plurality of characters adjacent to each other are included in the front surface image unit 21, the back surface image unit 22, and the base material image unit 23, as in the case of the specific character string. , They may be included in the same image unit.

[Manufacturing method of personal authentication medium]
A method of manufacturing the personal authentication medium 10 will be described with reference to FIGS. 6 to 9. In the following, before explaining the process for manufacturing the personal authentication medium 10, the transfer foil used for manufacturing the personal authentication medium 10 will be described. In the production of the personal authentication medium 10, a transfer foil for forming the front diffraction portion 12 and a transfer foil for forming the back surface diffraction portion 13 are used. Between the two transfer foils, the configurations of the portions transferred from each transfer foil to the image display layer 11 which is the transfer target are different from each other as described above, but the other portions are common. Therefore, in the following, the transfer foil for forming the front diffraction portion 12 will be described in detail, and the detailed description of the transfer foil for forming the back surface diffraction portion 13 will be omitted.

As shown in FIG. 6, the transfer foil 50 is a transfer foil used for forming the surface diffraction portion 12, and includes the above-mentioned surface diffraction portion 12 and a support layer 51 for supporting the surface diffraction portion 12. .. When the transfer foil 50 is formed, the support layer 51 is first prepared, and the support layer 51 can be embodied by, for example, a resin film. Of the support layer 51, the surface on which the surface diffraction portion 12 is formed may be subjected to a treatment for facilitating the surface diffraction portion 12 from being peeled off from the support layer 51.

Next, the diffraction layer 31 is formed on one surface of the support layer 51. When the concealing portion 31b of the diffraction layer 31 is formed of a metal film, a metal film having a predetermined shape is formed on the support layer 51. The concealing portion 31b may be formed by removing an unnecessary portion of the metal film after the metal film covering almost the entire surface of one surface of the support layer 51 is formed, or depending on the shape of the concealing portion 31b. It may be formed by film formation using a mask.

Then, after forming the coating film for forming the transmission portion 31a on the support layer 51, the original plate for forming the surface diffraction grating 31c on the surface of the coating film opposite to the surface in contact with the support layer 51 is applied. Push. As a result, the diffraction layer 31 having the surface diffraction grating 31c is formed on the back surface 31R. Next, the adhesive layer 32 is formed on the surface of the diffraction layer 31 opposite to the surface in contact with the support layer 51. Thereby, the transfer foil 50 can be obtained.

When the surface diffraction unit 12 has a transparent reflective layer, a transparent reflective layer may be formed on the back surface 31R of the diffraction layer 31 before the adhesive layer 32 is formed on the back surface 31R of the diffraction layer 31. The transparent reflective layer is formed by, for example, a vacuum vapor deposition method or a sputtering method.

As shown in FIG. 7, when manufacturing the personal authentication medium 10, first, the image display layer 11 is prepared. The image display layer 11 can be embodied by, for example, a resin film. Next, the front surface diffraction portion 12 is transferred to the front surface 11F of the image display layer 11 using the transfer foil 50 described above, and the back surface diffraction portion is used to form the back surface diffraction portion 13 on the back surface 11R of the image display layer 11. The part 13 is transferred. The transfer of the front surface diffraction unit 12 may be performed before the transfer of the back surface diffraction unit 13, or the transfer of the back surface diffraction unit 13 may be performed before the transfer of the front surface diffraction unit 12.

As shown in FIG. 8, the first base material 14 and the second base material 15 are prepared. Each of the first base material 14 and the second base material 15 can be embodied by, for example, a resin film. The first base material 14 can be embodied by, for example, various types of paper in addition to the resin film. Then, the front surface image portion 21 is formed on the surface 11F of the image display layer 11, the back surface image portion 22 is formed on the front surface 15F of the second base material 15, and the base material image portion 23 is formed on the surface 14F of the first base material 14. Form.

The front surface image portion 21 may be formed on the back surface 16R of the third base material 16, or a part of the front surface image portion 21 may be formed on the front surface 11F of the image display layer 11, and the back surface 16R of the third base material 16 may be formed. The remaining part of the surface image portion 21 may be formed on the surface. Further, the back surface image portion 22 may be formed on the back surface 11R of the image display layer 11, or a part of the back surface image portion 22 may be formed on the front surface 15F of the second base material 15 and may be formed on the back surface 11R of the image display layer 11. The remaining part of the back surface image portion 22 may be formed. Further, the base material image portion 23 may be formed on the back surface 15R of the second base material 15, or a part of the base material image portion 23 may be formed on the front surface 14F of the first base material 14, and the second base material 15 may be formed. The remaining part of the base material image portion 23 may be formed on the back surface 15R of the base material.

As shown in FIG. 9, the third base material 16 is prepared, and the first base material 14, the second base material 15, the image display layer 11, and the third base material 16 are stacked in the order described. Layers are integrated to form a laminated body. As a result, it is possible to obtain a laminated body in which the front diffraction unit 12 and the back surface diffraction unit 13 are included inside. Then, the image display layer 11 is irradiated with the laser beam LB from the third base material 16 side using the irradiation device 61 via the third base material 16 and the surface diffraction unit 12. The display unit 11a is formed. As a result, the personal authentication medium 10 described above with reference to FIGS. 1 to 5 can be obtained.

[Forming material for each part]
The forming material of each part constituting the personal authentication medium 10 will be described.
[Base material]
A resin film can be used for the first base material 14, the second base material 15, and the third base material 16. Examples of the resin forming the film include PET (polyethylene terephthalate), PEN (polyethylene terephthalate), PP (polypropylene), polyvinyl chloride resin (PVC), amorphous polyester resin (PET-G), and polycarbonate. Nate resin (PC) or the like can be used. Of these, PCV, PET-G, which have been conventionally used as base materials for cards and passports for personal authentication media, and films formed from PCs are easy to integrate by heat or pressure. preferable.

The thickness of each base material is preferably 50 μm or more and 400 μm or less. When the thickness of each base material is 50 μm or more, the physical strength of each base material is increased to the extent that each base material is easy to handle. Therefore, the front surface image portion 21, the back surface image portion 22, and the base material image It is possible to prevent wrinkles from being formed on each base material when the portion 23 is formed. Further, when the thickness of each base material is 400 μm or less, it is possible to suppress that the influence of the thickness variation and the bending of each base material becomes large when the personal authentication medium 10 is manufactured. The thickness of each base material is more preferably 75 μm or more and 100 μm or less.

[Image display layer]
For the image display layer 11, a resin film having a characteristic of developing color by irradiation with a laser beam having a predetermined wavelength can be used. For the image display layer 11, for example, a film formed of a polycarbonate resin and an energy absorber that absorbs a laser beam added to the polycarbonate resin can be used. Examples of such a film include SABIC's LEXAN series SD8B94.

The thickness of the image display layer 11 is preferably 50 μm or more and 400 μm or less, and more preferably 75 μm or more and 100 μm or less, for the same reason as each of the above-mentioned base materials.

[Image part]
The front surface image unit 21, the back surface image unit 22, and the base material image unit 23 have an arbitrary color in order to give predetermined information to the personal authentication medium 10, and also have patterns such as characters and patterns. doing.

Each image portion is formed using, for example, ink. As the ink for forming each image portion, offset ink, letterpress ink, gravure ink and the like can be used depending on the printing method, and for example, resin ink, oil-based ink, etc. And water-based ink can be used. Further, as the ink for forming each image portion, for example, an oxidation polymerization type ink, a penetration drying type ink, an evaporation drying type ink, and an ultraviolet curable type ink can be used depending on the difference in the drying method. ..

Further, as the ink forming each image portion, a functional ink whose color changes according to the angle of incidence of light on the personal authentication medium 10 or the angle at which the personal authentication medium 10 is observed can be used. Examples of the functional ink include an optical variable ink, a color shift ink, and a pearl ink.

Each image portion can also be formed by an electrophotographic method using toner. When forming each image part by the electrophotographic method, a toner in which colored particles such as graphite and pigment are attached to charged plastic particles is prepared, and the static electricity generated by the charge is used to apply the toner to the object to be printed. Transfer. Then, the toner is fixed on the object to be printed by heating the object to be printed to which the toner is transferred. As a result, each image unit can be formed on each of the above-mentioned base materials and the image display layer 11.

[Support layer]
The support layer 51 included in the transfer foil 50 for forming the front surface diffraction portion 12 and the support layer included in the transfer foil for forming the back surface diffraction portion 13 can be formed by using the following materials.

A resin film can be used for the support layer, and for example, PET, PEN, PP, and the like can be used as the film forming material. The film-forming material is preferably a material that is unlikely to be deformed or deteriorated by the heat applied to the support layer or the solvent in contact with the support layer when the diffraction layer is formed on the support layer. As the support layer, paper, synthetic paper, plastic multi-layer paper, resin-impregnated paper, or the like can also be used.

The thickness of the support layer is preferably 4 μm or more, and more preferably 12 μm or more and 50 μm or less. When the thickness of the support layer is 4 μm or more, the physical strength of the support layer is increased to the extent that the support layer is easy to handle.

[Diffraction layer]
Each of the transmission portion 31a included in the diffraction layer 31 in the front diffraction section 12 and the diffraction layer 41 included in the back surface diffraction section 13 can be formed by using the following materials.

For example, a thermoplastic resin and a thermosetting resin can be used as the material for forming the transmission portion 31a and the diffraction layer 41. Examples of the thermoplastic resin include acrylic resin, epoxy resin, cellulose resin, vinyl resin and the like. Examples of the thermosetting resin include urethane resin, melamine resin, epoxy resin, and phenol resin.

A photopolymer can also be used as a material for forming the transmission portion 31a and the diffraction layer 41. Photopolymers include monomers, oligomers, and polymers with ethylenically unsaturated bonds or ethylenically unsaturated groups. Among these, the monomers include, for example, 1,6-hexanediol, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexa. Examples include acrylate. Examples of the oligomer include epoxy acrylate, urethane acrylate, polyester acrylate and the like. Examples of the polymer include urethane-modified acrylic resin and epoxy-modified acrylic resin. It is also possible to use a photopolymer other than the above as the material for forming the transmission portion 31a and the diffraction layer 41.

[Adhesive layer]
Each of the adhesive layer 32 included in the front diffraction unit 12 and the adhesive layer 42 included in the back surface diffraction unit 13 can be formed by using the materials described below.

The adhesive layers 32 and 42 are formed of, for example, an adhesive containing a polyester resin, a urethane resin, an acrylic resin, a vinyl chloride resin, or the like as main components. The adhesive for forming the adhesive layer may contain an adhesive-imparting agent, a filler, a softening agent, a thermal light stabilizer, an antioxidant and the like.

Examples of the adhesive-imparting agent include rosin-based resin, terpene phenol-based resin, terpene resin, aromatic hydrocarbon-modified terpene resin, petroleum resin, kumaron-inden resin, styrene-based resin, phenol-based resin, and xylene resin. .. Examples of the filler include zinc oxide, titanium oxide, silica, calcium carbonate, barium sulfate and the like. Examples of the softener include process oils, liquid rubbers, and plasticizers. Examples of the thermal light stabilizer include benzophenone type, benzotriazole type and hindered amine type, and examples of the antioxidant include anilides type, phenol type, phosphite type and thioester type.

The thickness of the adhesive layers 32 and 42 is, for example, 0.1 μm or more and 10 μm or less, and preferably 1 μm or more and 5 μm or less.

[Example]
An example of a personal authentication medium will be described.
Before manufacturing the personal authentication medium, a transfer foil for forming the front diffraction portion and a transfer foil for forming the back surface diffraction portion were prepared. When forming the transfer foil for forming the surface diffraction portion, a PET film having a thickness of 25 μm (Lumirror 25T60, manufactured by Toray Industries, Inc.) (Lumirror is a registered trademark) was prepared as a support layer. Then, an aluminum layer having a thickness of 2 μm was formed on one surface of the PET film by a vacuum vapor deposition method using a mask, thereby forming a concealing portion.

Next, a diffraction layer ink having the following composition was applied to the surface of the PET film on which the concealing portion was formed by using a gravure printing method to form a coating film having a thickness of 2 μm. .. Then, after removing from the coating film by volatilizing the solvent contained in the coating film, a roll forming process is performed by pressing a metal cylindrical plate against the surface of the coating film opposite to the surface in contact with the support layer. went. As a result, a surface diffraction portion was formed. At this time, the press pressure ^{was set to 2} Kgf / cm 2, the press temperature was set to 240 ° C, and the press speed was set to 10 m / min.

A ZnS film having a thickness of 600 Å was formed as a transparent reflective layer by a vacuum vapor deposition method on the surface of the diffraction layer opposite to the surface in contact with the support layer. Next, a coating film having a thickness of 4 μm is formed by applying an adhesive layer ink having the following composition to the surface of the transparent reflective layer opposite to the surface in contact with the diffraction layer. bottom. Then, the solvent contained in the coating film was volatilized and removed from the coating film to form an adhesive layer. As a result, a transfer foil containing a surface diffraction portion was obtained.

Further, a transfer foil including the back surface diffraction portion was obtained by the same method as the method for forming the transfer foil including the front surface diffraction portion except for the step of forming the concealing portion.

[Ink for diffraction layer]
High molecular weight methacrylic (PMMA) resin 2 parts by mass Low viscosity nitrocellulose 12 parts by mass Cyclohexanone 10 parts by mass

[Ink for adhesive layer]
Polyester resin 20 parts by mass Methyl ethyl ketone 40 parts by mass Toluene 50 parts by mass

An image display layer (LEXAN SD8B94, manufactured by SABIC Co., Ltd.) (LEXAN is a registered trademark) having a thickness of 100 μm was prepared, and the surface diffractometer was transferred to the surface of the image display layer using a hot stamp transfer machine. The back surface diffractometer was transferred to the back surface of the image display layer. At this time, the transfer temperature was set to 120 ° C. and the transfer time was set to 1 second.

A first base material having a thickness of 400 μm (LEXAN SD8B24, manufactured by SABIC Co., Ltd.), a second base material having a thickness of 200 μm (LEXAN SD8B14, manufactured by SABIC Co., Ltd.), and a thickness of 100 μm. A third base material (LEXAN SD8B14, manufactured by SABIC Co., Ltd.) was prepared. Then, a base material image portion is formed on the surface of the first base material using black ink, a back surface image portion is formed on the surface of the second base material using black ink, and the surface of the image display layer is black. A surface image portion was formed using the ink of.

Next, the first base material, the second base material, the image display layer, and the third base material are stacked in the order described, and heat pressure is applied to these to laminate them and shape them into a card shape to form a card-like surface diffracting portion and a back surface. A laminate including a diffractive part was obtained.

Using a fiber laser type laser irradiation device that outputs a laser beam having a wavelength of 1064 nm, the image display layer of the laminate was irradiated with the laser beam from the side where the third base material is located. As a result, a display unit was formed inside the image display layer, and the personal authentication medium of the example was obtained.

In a plan view facing the surface of the personal authentication medium, the first image element, the second image element, and the third image element may overlap each other to form a specific image including the upper body image of the owner. Admitted. Further, when an attempt was made to remove the first image element, which is the image of the owner's upper body, from the back surface of the personal authentication medium, it was found that the third image element disappeared in addition to the removal of the first image element.

As described above, according to one embodiment of the personal authentication medium, the effects listed below can be obtained.
(1) Since the diffraction portions are located on the front surface 11F and the back surface 11R of the image display layer 11, it is difficult to remove only the portion of the image display layer 11 on which the display portion 11a is formed. Further, since the first image element PIC1, the second image element PIC2, and the third image element PIC3 form one specific image PIC, the front diffraction unit 12 and the back surface diffraction unit 13 with respect to the fake image display layer If the positions are not aligned, it is difficult for the fake personal authentication medium to display the same image as the specific image PIC displayed by the genuine personal authentication medium 10. Therefore, according to such a personal authentication medium 10, forgery of the personal authentication medium 10 can be suppressed.

(2) Since the face image is sandwiched by the pair of diffractive portions in the thickness direction of the personal authentication medium 10, it is difficult to replace the face image of the personal authentication medium 10 with another face image. Therefore, forgery of the personal authentication medium 10 can be suppressed.

(3) In order to form a fake specific character string so as to resemble a genuine specific character string, the position of each character forming the specific character string in a plan view facing the surface 11F of the image display layer 11 is set. It is necessary to align each character not only in the alignment but also in the thickness direction of the personal authentication medium 10. Therefore, it is more difficult to forge the specific character string than the configuration in which all the characters forming the specific character string are located on the same surface, and it is possible to suppress the forgery of the personal authentication medium 10.

(4) Only the third image element PIC3, which is a part of the basic image PICB formed by the back surface diffraction grating 41a, is visually recognized by the observer of the personal authentication medium 10. Therefore, when the personal authentication medium 10 is forged, there is a high possibility that only the diffraction grating that forms only the third image element PIC3 that can be visually recognized at the time of observation is forged. Therefore, in a plan view facing the front surface 10F of the personal authentication medium 10, whether or not the back surface diffraction unit 13 can form a basic image PICB larger than the third image element PIC3 is genuine. It is also possible to determine whether or not the personal authentication medium 10 is used.

The above-described embodiment can be appropriately modified and implemented as follows.
As shown in FIG. 10, the image display layer 11 included in the personal authentication medium 70 may include a second display unit 11b. The second display unit 11b is a portion that is colored by the image display layer 11 by irradiation with the laser beam LB, and overlaps both the front surface image unit 21 and the back surface image unit 22 in the thickness direction of the image display layer 11. And also contains at least one character. The second display unit 11b does not overlap with the base material image unit 23 in the thickness direction of the image display layer 11. As described above, the front surface image portion 21 and the back surface image portion 22 are formed of ink. When the personal authentication medium 70 is observed from the observing side, the front surface image unit 21, the back surface image unit 22, and the second display unit 11b are included in the specific character string.

The second display unit 11b is exposed on the front surface 11F of the image display layer 11, and extends to a portion closer to the front surface 11F than the back surface 11R in the thickness direction of the image display layer 11. The second display unit 11b may be exposed on the back surface 11R of the image display layer 11 and may extend to a portion closer to the back surface 11R than the front surface 11F in the thickness direction of the image display layer 11. Further, the second display unit 11b may be located on the entire thickness direction of the image display layer 11 so as to be exposed on both the front surface 11F and the back surface 11R of the image display layer 11.

According to such a configuration, the effects described below can be obtained.
(5) Since one specific character string contains characters formed by different forming materials, in order to forge the specific character string possessed by the personal authentication medium 70, the specific character strings have different forming materials. It is necessary to include the characters formed by. Therefore, as compared with the configuration in which the specific character string is formed by a single forming material, the forgery of the personal authentication medium 70 can be suppressed by the amount of man-hours and time required for forgery of the specific character string.

The front surface image unit 21 and the back surface image unit 22 may have a configuration described below with reference to FIG. In FIG. 11, the second base material 15 including the back surface diffraction portion 13 and the third base material 16 are not shown.

As shown in FIG. 11, in the personal authentication medium 80, each of the first character 1C, the second character 2C, and the third character 3C is an example of the specific character, and is included in the specific character string. It contains information for identifying the owner of the personal authentication medium 80.

The surface image unit 21 includes the surface element 2CF, and the surface element 2CF is located in a portion of the surface 11F of the image display layer 11 different from the portion where the surface diffraction unit 12 is located to identify the owner. It is a part of one specific character contained in the information of. The back surface image unit 22 is a portion of the back surface 11R of the image display layer 11 that is different from the portion where the back surface diffraction unit 13 is located, and overlaps with the front surface image unit 21 in the thickness direction of the image display layer 11. It is located in a non-existent part and contains the back surface element 2CR which is another part of the specific character. When the personal authentication medium 10 is observed from the side where the front surface diffraction unit 12 is located with respect to the image display layer 11, the front surface element 2CF and the back surface element 2CR form a character for identification.

For example, in the second character 2C constituting the second character string CHA2, a part of "T" which is one of the specific characters is the front surface element 2CF, and the other part of "T" is the back surface element. It is 2CR. Further, in the second character 2C, a part of "A" which is one of the specific characters is the front surface element 2CF, and the other part of the "A" is the back surface element 2CR. Further, in the second character 2C, a part of "K" which is one of the specific characters is the front surface element 2CF, and the other part is the back surface element 2CR. Among the specific characters, the front surface element 2CF and the back surface element 2CR are portions that are connected to each other when the personal authentication medium 80 is observed from the observing side.

According to such a configuration, the effects described below can be obtained.
(6) In order to form a fake identification character so as to resemble a genuine identification character, it is only necessary to align the front surface element 2CF and the back surface element 2CR in a plan view facing the front surface 11F of the image display layer 11. Therefore, it is necessary to align each element in the thickness direction of the image display layer 11. Therefore, it is more difficult to forge the specific character than the configuration in which all the elements forming the specific character are located on the same surface, and it is possible to suppress the forgery of the personal authentication medium 80.

(7) If the accuracy of the position of the back surface element 2CR with respect to the position of the front surface element 2CF is not high in the plan view facing the front surface 11F of the image display layer 11, a gap is formed between the front surface element 2CF and the back surface element 2CR. Alternatively, a part of the back surface element 2CR overlaps with a part of the front surface element 2CF, so that the shape of the specific character deviates from the desired shape. Therefore, it is possible to determine whether or not the specific character is a forged character based on the shape of the specific character.

The front surface element 2CF and the back surface element 2CR may be portions of the specific characters that are not connected to each other. Even with such a configuration, the effect according to (6) described above can be obtained.

The basic image PICB formed by the back surface diffraction unit 13 may have a size capable of being located inside the concealment unit 31b in a plan view facing the front surface 10F of the personal authentication medium 10. In this case, the entire basic image PICB is the third image element PIC3. Even with such a configuration, as long as one specific image PIC is formed by overlapping the first image element PIC1, the second image element PIC2, and the third image element PIC3, the above-mentioned (1) is applied. You can get the effect.

The surface diffraction unit 12 does not have to include the concealing unit 31b, and even with such a configuration, one identification is performed by overlapping the first image element PIC1, the second image element PIC2, and the third image element PIC3. As long as the image PIC is formed, the effect according to (1) described above can be obtained.

-In at least one of the first character string CHA1, the second character string CHA2, and the third character string CHA3, which are examples of the specific character strings, all the characters constituting each character string are on the same plane. May be located. Specifically, all the characters constituting one specific character string are located on either the front surface 11F of the image display layer 11, the back surface 11R of the image display layer 11, or the back surface 15R of the second base material 15. You may. Even with such a configuration, as long as one specific image PIC is formed by overlapping the first image element PIC1, the second image element PIC2, and the third image element PIC3, the above-mentioned (1) is applied. You can get the effect.

-At least one of the front surface image unit 21, the back surface image unit 22, and the base material image unit 23 is composed of a predetermined symbol, figure, and pattern in addition to or in place of the character string. You may. Such symbols, figures, and patterns may or may not include information for identifying the owner of the personal authentication medium 10.

The first image element PIC1 displayed by the display unit 11a does not have to include the face image of the owner of the personal authentication medium 10. The first image element PIC1 may be at least one of a character, a number, a symbol, a figure, and a picture. Even with such a configuration, as long as one specific image PIC is formed by overlapping the first image element PIC1, the second image element PIC2, and the third image element PIC3, the above-mentioned (1) is applied. You can get the effect.

-In the first image element PIC1, the second image element PIC2, and the third image element PIC3, at least one image element may include information for identifying the owner of the personal authentication medium 10. Also, the information for identifying the owner does not have to be included in the first image element PIC1. Even with such a configuration, as long as one specific image PIC is formed by overlapping the first image element PIC1, the second image element PIC2, and the third image element PIC3, the above-mentioned (1) is applied. You can get the effect.

The display unit 11a for displaying the first image element PIC1 does not have to be a portion formed by the color development of the image display layer 11. The display unit may be formed of ink or toner, as in the case of the front surface image unit 21, the back surface image unit 22, and the base material image unit 23 described above. In this case, the image display layer 11 does not have to have the property of developing color by irradiation with a laser beam, and the display unit includes the first base material 14, the second base material 15, the image display layer 11, and the display unit. It may be formed on the image display layer before laminating the third base material 16.

10, 70, 80 ... Personal authentication medium, 10F, 11F, 14F, 15F, 16F ... Front surface, 10R, 11R, 14R, 15R, 16R, 31R, 41R ... Back surface, 11 ... Image display layer, 11a ... Display unit, 11b ... 2nd display unit, 12 ... front surface diffraction unit, 12a, 31a ... transmission unit, 12b, 31b ... concealment unit, 13 ... back surface diffraction unit, 14 ... first base material, 15 ... second base material, 16 ... third Base material, 21 ... front surface image part, 22 ... back surface image part, 23 ... base material image part, 31, 41 ... diffraction grating, 31c ... front surface diffraction grating, 32, 42 ... adhesive layer, 41a ... back surface diffraction grating, 50 ... Transfer foil, 51 ... Support layer, 61 ... Irradiation device, PIC ... Specific image, CHA1 ... 1st character string, CHA2 ... 2nd character string, CHA3 ... 3rd character string, CHA4 ... 4th character string, CHA5 ... 5 character strings, PIC1 ... 1st image element, PIC2 ... 2nd image element, PIC3 ... 3rd image element, PICB ... basic image, 1C ... 1st character, 2C ... 2nd character, 2CF ... front element, 2CR ... back side Element, 3C ... 3rd character, 4C ... 4th character, 5C ... 5th character.

Claims (5)

An image display layer that includes a display unit that displays the first image element and also includes a front surface and a back surface.
A surface including a surface diffraction grating that is located on the surface so as to overlap the display portion in the thickness direction of the image display layer and emits diffracted light as reflected light to form a second image element by the diffracted light. Diffractive part and
The back surface diffraction unit located on the back surface so as to sandwich the display unit between the front surface diffraction unit and the back surface diffraction unit and to spread outward from the display unit, and to be a region overlapping the display unit. It is provided with a region that does not overlap with the display unit, and also includes the back surface diffraction unit including a back surface diffraction grid that emits diffracted light as reflected light and forms a third image element by the diffracted light.
In the thickness direction of the image display layer, the front surface diffraction portion has transparency at a portion where the display portion and the back surface diffraction grating overlap, and the portion of the image display layer other than the display portion is , Has transparency at the part overlapping the backside diffraction grating,
The side where the surface diffraction portion is located with respect to the image display layer is the observation side of the personal authentication medium.
When the personal authentication medium is observed from the observing side, the first image element, the second image element, and the third image element include information for identifying the owner of the personal authentication medium. Form one specific image ,
A first surface image portion located in a portion of the surface different from the portion where the surface diffraction portion is located and containing at least one character, and a first surface image portion.
At least one character is located on the back surface of the back surface, which is different from the portion where the back surface diffraction portion is located and which does not overlap with the first surface image portion in the thickness direction of the image display layer. Further equipped with a first back surface image unit including
When the personal authentication medium is observed from the observing side, the first front surface image unit and the first back surface image unit are included in one identification character string including information for identifying the owner. ,
The display unit is the first display unit.
The image display layer has a property of developing color by irradiation with a laser beam, is a portion colored by the image display layer by irradiation with the laser beam, and is the first surface in the thickness direction of the image display layer. A second display unit that does not overlap with both the image unit and the first back surface image unit and includes at least one character is further included.
The first front surface image portion and the first back surface image portion are formed by ink.
When the personal authentication medium is observed from the observation side, the first surface image unit and the first back surface
A personal authentication medium in which the surface image unit and the second display unit are included in the specific character string. The first display unit is a portion that develops color in the image display layer by irradiation with the laser beam.
The personal authentication medium according to claim 1, wherein the first image element includes a face image of the owner. Located in a site different from where the surface diffractive portion is positioned among said surface, a second surface that includes one surface element which is part of the specific character included in the information for identifying the owner Image part and
The specific character is located on the back surface of the back surface, which is different from the portion where the back surface diffraction portion is located and which does not overlap with the second surface image portion in the thickness direction of the image display layer. It further comprises a second backside image section that includes a backside element that is another part of the
The personal authentication medium according to claim 1 or 2 , wherein when the personal authentication medium is observed from the observation side, the front surface element and the back surface element form the specific character. The personal authentication medium according to claim 3 , wherein the front surface element and the back surface element are portions of the specific characters that are connected to each other when the personal authentication medium is observed from the observation side. The surface diffraction grating includes the surface diffraction grating and forms an edge of the surface diffraction grating, which is located outside the surface diffraction grating in a plan view facing the surface and the transmission portion having transparency. , A concealing portion that conceals an image formed by the lower layer of the surface diffraction portion, and the like.
The back surface diffraction grating contains the third image element inside, and is a basic image on which the third image element is based. In a plan view facing the surface, the back surface diffraction grating protrudes from the transmission portion and has an edge. The personal authentication medium according to any one of claims 1 to 4 , which forms the basic image having the following size.

Images