JP7697232B2 - Anti-counterfeiting media - Google Patents

Description

The present invention relates to a medium that requires an anti-counterfeiting effect, and in particular to an anti-counterfeiting medium that has a latent image effect in which the image changes under visible light.

Counterfeiting prevention technologies applied to passports and ID cards include an image change effect, where multiple images switch between them, and a video effect, where the image appears to move. In recent years, variable information has been combined with security media with a changing effect or video effect to prevent tampering. One technology that combines the change effect and variable information to improve security is to apply a lenticular lens, a well-known technology, to form a kamaboko-shaped lens on a base material that changes color when exposed to laser light, and then print variable information on the base material with laser light. When viewed from different angles, A and B, as shown in Figure 7, different patterns are seen alternating, such as personal information written in text and a facial photograph, creating a changing effect (Patent Document 1).

Alternatively, a printed pattern with special optical effects such as light-dark flip-flop or color flip-flop is provided on the substrate, and a kamaboko lens is layered on the printed pattern, providing a changing effect in which different image patterns are visible depending on the angle from which the medium is viewed, thereby enhancing security (Patent Document 2).

On the other hand, when issuing security media such as ID cards or passports, personal information is added using a laser printer or a thermal transfer printer, and then a colorless and transparent protective layer, such as a holographic layer, is sometimes added at the end. However, when a lenticular lens is used to provide a changing effect as a security technology for these media, as shown in Figure 8, if a protective layer such as a holographic film is placed on top of the lenticular lens, the optical path will shift, and for example an image that should be visible from viewpoint B will be visible from viewpoint A, compromising the changing effect of the image, etc., placed on the base material. As a countermeasure, it becomes necessary to devise and process a way to not add a protective layer only on top of the lenticular lens, resulting in increased costs and additional processes.

U.S. Pat. No. 4,765,656 Patent No. 6300101

The objective of the present invention is to provide a counterfeit prevention medium that can generate a changing effect without impairing the changing effect even when a protective layer is provided on an image having a changing effect, and without being affected by deviations in the optical path, etc.

In order to solve the above problems, the present invention provides
The counterfeit prevention medium is characterized in that a blazed grating having a symmetrical sawtooth cross section is formed on at least a portion of a substrate, and a pattern for forming a first image is formed on a sawtooth surface facing a first direction of the blazed grating, and a pattern for forming a second image is formed on a sawtooth surface facing a second direction.

The anti-counterfeiting medium may have a light-transmitting blazed grating.

The anti-counterfeiting medium may be one in which the pattern forming the first image and the pattern forming the second image are formed by ink transferred from a thermal transfer ribbon.

The counterfeit prevention medium may further include a light-transmitting protective layer laminated on the blazed grating and the pattern.

According to the present invention, it is possible to easily obtain an anti-counterfeiting medium on which an image having a suitable changing effect is formed for media requiring security, such as ID cards and passports, and even if a protective layer is added in a later process, the changing effect is not impaired due to changes in the light path, etc., and an anti-counterfeiting medium is obtained that allows for simplified processing and reduced costs.

1 is a schematic cross-sectional view of a portion of a counterfeit prevention medium of the present invention where a blazed grating is formed. FIG. 2 is a schematic cross-sectional view of an embodiment in which a changing image pattern is formed. 10 is a schematic cross-sectional view illustrating a changing effect. 1 is a schematic cross-sectional view illustrating a changing effect when a protective layer is provided. FIG. FIG. 1 is a diagram showing an example of a card-shaped counterfeit prevention medium according to the present invention. FIG. 6 is an external view illustrating a changing effect in the example of FIG. 5 . 1 is a schematic cross-sectional view of a conventional example of a medium on which a changing image is formed. FIG. 8 is a schematic cross-sectional view of the conventional example of FIG. 7 when a protective layer is provided.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that the present invention is not limited to the embodiments described below. In addition, the embodiments described below have technically preferable limitations for implementing the invention, but these limitations are not essential requirements for the present invention.

Figure 1 is a schematic cross-sectional view of a portion of the anti-counterfeiting medium of the present invention where a blazed grid is formed, showing the state before a changing image pattern is recorded. The anti-counterfeiting medium 1 has a blazed grid 3 with a sawtooth cross section formed on at least a portion of a substrate 2. There are no particular limitations on the substrate 2 as long as it is a material with adequate strength, durability and processability as a medium. For example, polycarbonate resin is preferably used, but it may also be paper, synthetic paper, or synthetic resin such as polyethylene terephthalate resin (thermoplastic PET), polyvinyl chloride resin, thermosetting polyester resin, polymethacrylic resin, and polystyrene resin as long as it does not affect the formation of the blazed grid 3 described below.

The blazed grating 3 formed on the substrate 2 can be formed by applying a resin such as a thermoplastic resin, a thermosetting resin, and an ultraviolet-curable resin or an electron beam-curable resin (hereinafter collectively referred to as a photocurable resin) to the substrate, pressing a mold having projections and recesses onto the resin surface to transfer the projections and recesses, and then curing the resin.

Examples of thermoplastic resins include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, nitrocellulose, polyethylene, polypropylene, acrylic-styrene copolymer, vinyl chloride, and polymethyl methacrylate.

Examples of thermosetting resins include polyimide, polyamide, polyester urethane, acrylic urethane, epoxy urethane, silicone, epoxy and melamine resins.

Photocurable resin refers to a resin that cures when irradiated with light such as ultraviolet light or electron beams. Representative resins that undergo radical polymerization when irradiated with light include acrylic resins having acryloyl groups in the molecule, such as epoxy acrylate, urethane acrylate, polyester acrylate, or polyol acrylate oligomers or polymers, monofunctional, bifunctional, or polyfunctional polymerizable (meth)acrylic monomers (e.g., tetrahydrofurfuryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, or pentaerythritol tetraacrylate), or oligomers or polymers thereof, or mixtures thereof.

The above thermoplastic resins, thermosetting resins, and photocurable resins may be optically transparent.

After the above-mentioned embossing process, an ink pattern is formed on the sawtooth peaks of the blazed grating so that a first image, image A, appears on the sawtooth surface 4 facing a first direction, i.e., the surface at an angle seen from viewpoint A, and a second image, image B, appears on the sawtooth surface 5 facing a second direction, i.e., the surface at an angle seen from viewpoint B (Figure 2).

The ink pattern can be formed, for example, by transferring a pattern of thermal transfer ink from a thermal transfer ribbon. Any known thermal transfer ribbon can be used, but to improve the visibility of the image, it is preferable that the color of the thermal transfer ink on the thermal transfer ribbon is a dark color such as black. Images A and B can also include individual information, such as a photograph, name, ID number, and other text data, without any particular limitation.

Specific methods for forming image patterns on the sawtooth surface 4 facing the first direction and the sawtooth surface 5 facing the second direction with thermal transfer ink of a thermal transfer ribbon include thermal transfer using a high-definition thermal head with thermal transfer ink of a thermal transfer ribbon, and also high-definition laser thermal transfer using laser light. Also, an indirect thermal transfer method can be adopted in which the image patterns of images A and B are first transferred from the thermal transfer ribbon to an intermediate transfer medium by a thermal head or laser thermal transfer, and then thermally transferred again onto the blazed grating using a heat roller or the like.

The above-mentioned recording method of transferring thermal transfer ink from a thermal transfer ribbon is the same as the method used to record normal visual images on media such as cards and booklets, and does not require any special processes, making it possible to form changing images efficiently and at low cost.

In addition to the above, known image forming techniques such as inkjet printing, laser printing technology, screen printing technology, hot stamp transfer, and photolithography technology may be appropriately selected and used, but it is preferable to use a technique suitable for recording individual information.

An image of the counterfeit prevention medium 1 thus obtained is shown in Figure 3, where image A formed by the ink pattern of sawtooth surface 4 facing in a first direction is visible from viewpoint A, and image B formed by the ink pattern of sawtooth surface 5 facing in a second direction is visible from viewpoint B, thereby obtaining a changing effect. Furthermore, when a colorless and transparent protective layer 6 is provided as shown in Figure 4, even if the light path changes, what is visible is the image on the same sawtooth surface, and an image of a sawtooth surface facing in a different direction is not visible, for example, an image of viewpoint B is not visible from viewpoint A, and a medium that does not impede the changing effect can be obtained.

The protective layer 6 is a substantially transparent layer so that each image on the surface of the anti-counterfeiting medium 1 underneath can be seen. However, as long as visibility is not impaired, it may contain, for example, a transparent hologram layer, a printed layer, a vapor deposition layer, a barrier layer, etc., and may also contain ultraviolet absorbers, infrared absorbers, and other various additives. The protective layer 6 may be provided by a known method such as transfer, printing, or coating after each image on the surface of the anti-counterfeiting medium 1, including the image on the blazed grating 3, is formed, or it may be transferred and formed at the same time as each image is transferred from the intermediate transfer medium by an indirect thermal transfer method.

Figure 5 (a) is a schematic diagram showing one form of the anti-counterfeiting medium of the present invention to which a changing image has been applied, and is an example in the form of card 7. Card 7 is, for example, an ID card, on which personal information such as a face photo, name, and other personal information is recorded. A blazed grid is formed in part of the surface of card 7, in this example, area S in the lower right corner, and images A and B, which become the changing images, are recorded. In this case, image A is a face photo, and image B is letters indicating the date of birth. When card 7 is viewed from its normal direction, images A and B overlap and both can be seen.

In this example, the blazed grating is formed so that the sawtooth pattern extends horizontally in the figure of card 7. Therefore, when images A and B are enlarged and viewed from the normal direction, as shown in Figure 5(b), image A is formed only on the part that corresponds to sawtooth surface A, and image B is formed only on the part that corresponds to sawtooth surface B, resulting in a linear pattern extending horizontally. Also, as shown in the enlarged partial view in Figure 5(c), the linear patterns of images A and B are formed in a positional relationship where they are staggered. Note that the direction in which the sawtooth pattern is formed is not limited to the horizontal direction in the figure, and it may be formed so that it extends vertically or diagonally.

Figure 6 is an external view explaining the changing effect of card 7 in Figure 5, and is an image of what happens when card 7 is tilted vertically. For example, when card 7 is tilted at an angle so that it is viewed from viewpoint A, only image A is visible in area S. Conversely, when it is tilted at an angle so that it is viewed from viewpoint B, only image B is visible in area S. In this way, the changing effect is manifested. If the direction in which the sawtooth pattern is formed is the vertical direction in the figure, a similar changing effect is manifested when card 7 is tilted horizontally.

1: Anti-counterfeiting medium 2: Substrate 3: Blazed grating 4: Sawtooth surface facing a first direction 5: Sawtooth surface facing a second direction 6: Protective layer 7: Anti-counterfeiting medium (card)

Claims (4)

A counterfeit prevention medium, characterized in that a blazed grating having a symmetrical sawtooth cross section is formed on at least a portion of a substrate, and a pattern for forming a first image is formed on a sawtooth surface facing a first direction of the blazed grating, and a pattern for forming a second image is formed on a sawtooth surface facing a second direction. The counterfeit prevention medium according to claim 1, characterized in that the blazed grating is optically transparent. The counterfeit prevention medium according to claim 1 or 2, characterized in that the pattern forming the first image and the pattern forming the second image are formed by ink transferred from a thermal transfer ribbon. An anti-counterfeiting medium according to any one of claims 1 to 3, characterized in that a light-transmitting protective layer is further laminated on the blazed grating and the pattern.