JP7536252B2 - Anti-counterfeiting media - Google Patents

Description

The present invention relates to a counterfeit prevention medium that makes it difficult to reuse a transfer foil that has a glossy finish when it is removed from a banknote, security, passport, identification card, etc., and that makes it easy to determine whether the transfer foil has been used for counterfeiting or tampering.

Valuables such as banknotes, securities, passports, revenue stamps, product tags, toll road passes, and various tickets are equipped with anti-counterfeiting technology to guarantee and maintain their value. Anti-counterfeiting elements that are particularly effective in preventing copying and duplication include threads made of transfer foil and holograms formed on a base material, and these have been applied to many valuables.

However, when malicious individuals counterfeit banknotes, securities, etc. that have transfer foil such as threads or holograms, they can substitute metal foil with a similar lustre to create a simple counterfeit, and a user who observes only the lustre of the counterfeit may mistake the counterfeit for a genuine product. There is also the problem that the transfer foil affixed to a genuine product may be peeled off in some way and used for counterfeiting or tampering. As a result, there is a demand for valuables that have transfer foil with improved anti-counterfeiting properties.

As a more effective anti-counterfeiting technology for transfer foils affixed to a base material, the applicant has filed a patent application for a three-dimensional image forming body with excellent design, in which letters and images can be observed three-dimensionally. (See Patent Document 1)

Patent Document 1 describes a three-dimensional image forming body in which a transfer foil laminated on a base material is engraved with a concave or convex shape to form an image in which lustrous image lines are arranged in a line pattern. When the observation angle is continuously changed under a light source in a fixed position, the position that reflects the incident light from the light source gradually moves along the arc-shaped lustrous image lines, and the phases of the images viewed by the left and right eyes differ, so that an image viewed two-dimensionally before the change in observation angle can be dynamically viewed three-dimensionally due to binocular parallax and as the observation angle changes.

In addition, a technology has been proposed that prevents the transfer foil from peeling by applying an embossing process, and makes it impossible to reuse the foil when it is peeled off. (See Patent Document 2)

Patent Document 2 is an invention relating to a document having a transfer foil at a predetermined location on a substrate, and an anti-counterfeiting uneven structure formed on the transfer foil by embossing, thereby improving the anti-counterfeiting effect. By forming the anti-counterfeiting uneven structure on at least a part of the transfer foil, when light is irradiated onto the anti-counterfeiting uneven structure, the shine caused by the reflection of light can be visually recognized, and by forming the anti-counterfeiting uneven structure on the substrate so as to straddle the transfer foil, it also serves the role of a tally seal. With this configuration, when the anti-counterfeiting mark is peeled off from the document, the anti-counterfeiting mark is significantly deformed, and when the peeled off anti-counterfeiting mark is attached to another valuable document, it becomes possible to detect the deformation of the anti-counterfeiting mark.

Patent No. 5799431 Patent No. 3053209

Patent Document 1 aims to provide a single stereoscopic image that can be viewed stereoscopically and dynamically with the naked eye, in contrast to the problem of having to line up two identical images in order to view it stereoscopically and dynamically using binocular parallax in the past. It is not intended to prevent the foil from peeling off by providing the effect of a tally seal.

In Patent Document 2, the uneven structure formed on the transfer foil is easily identifiable by the reflection of light from a light source, but the uneven structure formed on the base material is difficult to identify depending on the amount of light and angle of the light source because the shadow of the unevenness caused by the light source is visible. Therefore, if the uneven structure of the transfer foil is peeled off in some way without being destroyed and the transfer foil is reattached to the counterfeit product, even if the uneven shape formed on the foil and the lines of the uneven shape formed on the base material are not continuous, there is a risk that it will be mistakenly determined to be a genuine product due to its low identifiability, and it is not effective as a tally seal.

The present invention aims to solve the above-mentioned problems by providing an anti-counterfeiting medium that has an effect of preventing the foil from peeling off, by forming an image consisting of a concave or convex structure that can move dynamically and three-dimensionally by changing the observation angle, so that the image straddles the substrate and the foil, so that even if the foil is peeled off and an attempt is made to reuse the medium, part of the image formed on the substrate cannot be reproduced. As a further effect, the image that straddles the substrate and the foil can be observed dynamically and three-dimensionally continuously, providing an anti-counterfeiting medium that makes it easy to distinguish counterfeits and tampering.

In order to achieve the above-mentioned object, the counterfeit prevention medium of the invention described in claim 1 is a counterfeit prevention medium having an image on a part of a substrate, and when observing the image, a stereoscopic image can be dynamically observed depending on the observation angle and binocular parallax, and is characterized in that a first optically changeable layer having light/dark flip-flop properties and/or color flip-flop properties is formed on a part of the substrate, and an image forming area for forming an image is provided at a position spanning the first optically changeable layer and the substrate, and the image is formed by arranging arc-shaped information lines having a starting point, a vertex and an end point in a line pattern, and the cross-sectional shape of the information lines is a concave or convex shape.

The invention described in claim 2 is characterized in that, in the counterfeit prevention medium described in claim 1, the image is formed by arranging a plurality of circular information lines, each of which is made up of an arc-shaped information line and an inverted arc-shaped information line that is inverted with respect to a reference line connecting the start point and end point of the arc-shaped information line.

The invention described in claim 3 is characterized in that in the counterfeit prevention medium described in claim 1, the cross-sectional shape of the substrate is a concave or convex shape corresponding to the information image lines.

The invention described in claim 4 is characterized in that the image forming area on the substrate has light/dark flip-flop properties and/or color flip-flop properties.

The invention described in claim 5 is characterized in that the image forming area in the substrate has a second optically variable layer having light/dark flip-flop properties and/or color flip-flop properties.

The counterfeit prevention medium of the present invention, configured as described above, has an arc-shaped uneven image formed across the substrate and the first optically changeable layer, such as a metal foil or OVD foil, making it difficult to tamper with the foil by peeling it off, and also making it easy to determine whether the counterfeit prevention medium has been counterfeited or tampered with. In addition, when the foil is peeled off, the uneven image formed on the foil is deformed by the peeling force applied, making it impossible to reuse. Furthermore, by forming an arc-shaped uneven image so as to straddle the glossy substrate and the first optically changeable layer, a three-dimensional, continuously moving three-dimensional image can be viewed with the naked eye on both the substrate and the first optically changeable layer.

Overall view of the counterfeit prevention medium (S1) Cross-sectional view of the first optically variable layer (2) A plan view of an image (3) formed across a substrate (1) and an optically variable layer (2) Plan view showing details of image (3) and element area (3E) An enlarged plan view of one of the information lines (4) Cross-section of information line (4) Plan views showing various forms of image (3) Plan views showing various forms of image (3) Plan views showing various forms of image (3) A counterfeit prevention medium (S2) in which the substrate (1) is a substrate (1b) having a glossy property A counterfeit prevention medium (S3) in which a second optically variable layer (6) is applied to a substrate (1). A plan view of image (3) and a stereoscopic image (7) visible from image (3). FIG. 1 shows a viewpoint for observing a substrate (1) on which an image (3) is applied. A schematic diagram showing the principle of visual recognition of the information line (4) at a second observation angle (E2) Plan view of information line (4), images (3L, 3R) and stereoscopic image (7) observed from left and right viewpoints Schematic diagram showing continuous change in observation angle (θ4) relative to the substrate (2)

Embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and various other embodiments are included within the scope of the technical ideas described in the claims.

First Embodiment
FIG. 1 is a plan view showing a counterfeit prevention medium (S1) in which an image (3) is applied so as to straddle a substrate (1) and a first optically variable layer (2). An example of the counterfeit prevention medium (S1) is a gift certificate. The counterfeit prevention medium (S1) has information about the counterfeit prevention medium (S1), such as a store name and a type of ticket, applied on the substrate (1) with commonly used inks such as cyan, magenta, and yellow. The first optically variable layer (2) has a light-dark flip-flop property and/or a color flip-flop property. The counterfeit prevention medium (S1) has an image forming area (5) on at least a part of the substrate (1) and the first optically variable layer (2). An image (3) is arranged in the image forming area (5).

(Substrate)
The substrate (1) used in the anti-counterfeiting medium (S1) may be paper used in general printing, plastic, etc., and is not particularly limited as long as it is a substrate to which the first optically changeable layer (2) can be attached and to which a relief pattern can be imparted by pressing, and may have light/dark flip-flop properties and/or color flip-flop properties.

The light-dark flip-flop property is a change in brightness that occurs when the observation angle at which reflected light from the light source (Q) is changed, and the color flip-flop property is a change in hue that occurs when the observation angle at which reflected light from the light source (Q) is changed. There are two main observation angles, as shown in Figure 12: the observation angle (E2) at which light from the light source (Q) can be observed as specularly reflected by the substrate (1), and the other observation angle (E1). Details will be explained in the observation principle section below.

Hereinafter, color flip-flop properties and/or color flip-flop properties will be collectively referred to as glitter properties.

In the first embodiment, a configuration in which the substrate (1) does not have luster is described.

(Regarding the first optically changeable layer)
The first optically variable layer (2) attached to the counterfeit prevention medium (S1) is a glittering OVD (Optically Variable Device) foil or a metal foil.
These are applied by heat and pressure to a substrate (1). Figure 2 shows a cross section of a commonly used OVD foil (2) with a diffraction grating.

OVD foil (2) refers to a foil-like form in which elements such as color and pattern optically change depending on the light source and the viewing angle are processed into a thin plastic film. A typical OVD foil (2) is composed of a protective layer (2a), a diffraction grating processing layer (2b), and an adhesive layer (2c). The diffraction grating processing layer (2b) is transparent or semi-transparent, and a diffraction grating is applied to its surface. The diffraction grating is composed of a diffraction grating non-latent image part that does not have a latent image and a diffraction grating latent image part that shows a latent image, and is adhered to the substrate (1) via an adhesive layer. The OVD foil (2) may be provided with a metal layer made of metal foil to make the latent image of the diffraction grating appear more clearly (not shown). In addition, the diffraction grating itself is not a required component, and the OVD foil may be composed of only a plastic film having a lustrous property and an adhesive layer (not shown).

The metal foil is a foil made of a metal material such as gold, silver, or aluminum. It is preferable to provide an adhesive layer that enables adhesion to the substrate (1), but this is not a required component as long as it can be adhered to the substrate (1).

There is no limit to the thickness of the first optically variable layer (2) as long as it is possible to form uneven lines by embossing, laser processing, or the like. For example, a typical OVD foil has a thickness of several μm, and this can be used.

(image)
The structure of image (3) will be described below, however, the structure of image (3) is not limited to the following description. When observed by continuously changing the angle from a predetermined angle to a different angle with respect to a light source in a fixed position, a three-dimensional image (7) described below can be observed three-dimensionally and dynamically. As long as image (3) is formed across the substrate (1) and the first optically change layer (2), the technical idea of the present invention is met.

For example, the technical concept of the present invention also includes cases where the image lines described in Patent Nos. 5,799,431, 6,097,994, 6,583,632, and 6,061,192 are formed across the optical change layer (2) and the substrate (1).

Figure 3 is a plan view showing the arrangement of the image (3) on the counterfeit prevention medium (S1). The image (3) is formed from arc-shaped lines as shown in Figure 4 (a), and the image formation area (5) where the image is formed is divided into an image formation area (5a) where the image (3) is formed on the first optically changeable layer (2) and an image formation area (5b) where the image is formed on the substrate. The image (3) formed on the image formation area (5a) has a lustrous property, and by continuously changing the angle from a predetermined angle to a different angle with respect to the light source, the image (3) can be observed as a stereoscopic image (7) that can be observed three-dimensionally and dynamically. The fact that it can be observed three-dimensionally and dynamically is the same as the principle of observation by binocular parallax disclosed in Patent No. 5799431, and details will be described later.

(Line composition of image (3))
Fig. 4(a) is a plan view showing details of the image (3). The image (3) is composed of at least one element region (3E). Each element region (3E) is a part that constitutes the image (3). For example, the image (3) shown in Fig. 4 has an "N" shape and is composed of five element regions (3E) shown by thick lines. For the sake of clarity, lines showing the element regions (3E) are shown, but these are imaginary lines and are not formed in the actual image (3). Details of the method of dividing the image (3) into element regions (3E) will be described later.

Fig. 4(b) is an enlarged view of one element region (3E) shown in Fig. 4(a). The element region (3E) is formed by arranging a plurality of arc-shaped information lines (4) in a line pattern. In Fig. 4, the information lines (4) are formed at a first pitch (P1).
The term "line pattern" refers to a state in which a plurality of image lines are arranged (regularly) at a predetermined pitch.

In FIG. 4(b), when the straight line connecting the start point (U) and the end point (D) of the information image (4) arranged in the element area (3E) is set as the reference line (H1), the reference line (H1) is arranged in the same direction in a line pattern. In this case, the reference lines (H1) are parallel to each other in the multiple information images (4). By setting the reference lines (H1) in the same direction, the information images (4) are arranged in the first direction (X1) in the first element area (3E), and the vertices (T) are also formed to face the first direction (X1). In this way, an image (3) consisting of multiple information images (4) arranged in a line pattern with the reference lines (H1) in the same direction can be viewed as a three-dimensional image (7) that can be dynamically viewed in the left and right directions, as described below.

In FIG. 4, the reference lines (H1) of the information image lines (4) are described as having the same direction, but they can also have different directions. In FIG. 4(c), when the reference line (H1a) is set to 0 degrees, the angle between the reference line (H1b) and the reference line (H1e) gradually changes within the element area (3E). In other words, the directions of the information image lines (4) are different within the element area. Even in this case, it is sufficient that the vertices (T) are uniformly positioned at either the top or bottom of the area divided within the element area (3E) with the reference line (H1) at the center.

Next, using Figure 5, we will explain the range of the angle (θ1) made by the tangent (H2) of the information line (4) to the reference line (H1) at the starting point (U), and the angle (θ2) made by the tangent (H3) of the information line (4) to the reference line (H1) at the end point (D).

If the angles (θ1) and (θ2) are each less than 2 degrees, the reflected light from the start point (U) and end point (D) of the information image (4) will be reflected in approximately the same direction, making binocular parallax impossible at an appropriate observation distance, which is undesirable. Conversely, if the angles (θ1) and (θ2) are each more than 90 degrees, the reflected light from the start point (U) and end point (D) will be reflected in different directions, but will be outside the range where binocular parallax is possible.

Therefore, the angle (θ1) between the tangent (H2) of the information line (4) to the reference line (H1) at the starting point (U) and the angle (θ2) between the tangent (H3) of the information line (4) to the reference line (H1) at the end point (D) can be set appropriately within the range of 2 to 90 degrees.

It is preferable that the angle (θ1) between the reference line (H1) and the tangent (H2) of the information image (4) to the reference line (H1) is the same for all information images (4) at the starting point (U). It is also preferable that the angle (θ2) between the reference line (H1) and the tangent (H3) of the information image (4) to the reference line (H1) is the same for all information images (4) at the end point (D).

As described above, the information image (4) is arranged within the element area (3E). When the image (3) is viewed stereoscopically by binocular parallax, if the angle (θ1) on the starting point (U) side and the angle (θ2) on the ending point (D) side are the same angle, the direction of the reflected light from the first information image (4) will be the same for all information images (4). This makes it possible to clearly view the image (3) with the naked eye. On the other hand, if the angle (θ1) on the starting point (U) side and the angle (θ2) on the ending point (D) side are different angles, the direction of the reflected light from the information image (4) will vary. As a result, the image (3) will be viewed as a blurred image, which is undesirable.

In the following, in this embodiment, the reference line (H1) of the information image (4) is arranged in the first direction (X1), which is the same direction as shown in FIG. 4, and the angle (θ1) made by the tangent (H2) of the information image (4) to the reference line (H1) at the starting point (U) and the angle (θ2) made by the tangent (H3) of the information image (4) to the reference line (H1) at the end point (D) are the same for multiple information images (4) arranged on the substrate (2).

Next, the pitch (P1) for arranging the information image lines (4) will be described. The pitch (P1) can be set appropriately within the range of 5 to 1000 μm, taking into consideration the method for forming the information image lines (4), the substrate (1) used, and the image line width.

If the pitch (P1) is less than 5 μm, it becomes difficult to form the information lines (4) on the substrate (1), which is not preferable.

On the other hand, if the pitch (P1) exceeds 1000 μm, the non-glossy areas between adjacent information lines (4) become visible to the naked eye. This is undesirable because it results in areas in the image (3) that do not have gloss, reducing visibility when viewing the image (3) three-dimensionally.

In FIG. 4, the pitch (P1) is illustrated as being the same regular pitch, but it is also possible to use a random pitch. However, when considering the visibility of the stereoscopic image, if the image (3) made up of the information lines (4) is viewed with a uniform brilliance, it is easier to view it as a stereoscopic image (7). Therefore, it is preferable to form the pitch of the information lines (4) at a regular pitch (P1).

The width of the information line (4) is set appropriately within the range of 5 to 1000 μm, taking into account the pitch (P1).

If the image width is less than 5 μm, it is difficult to form the information image (4) on the substrate (1), which is not preferable.

On the other hand, if the image width is 1000 μm or more, the shape of image (3) must be enlarged to correspond to the image width. Enlarging image (3) makes it difficult to view image (3) stereoscopically due to binocular parallax, which is not preferable.

Figure 6(a) is an enlarged view of one of the information lines (4) shown in Figure 4. When the information line (4) is cut along the line A-A' shown in the figure, the cross section of the information line (4) may be either a convex shape as shown in Figure 6(b) or (d) or a concave shape as shown in Figure 6(c) or (e). In this case, in order to achieve a smooth dynamic effect, it is preferable that the cross section is not a square, triangle, or other angular shape, but a smooth shape without corners, such as a kamaboko shape, semicircular shape, or semi-elliptical shape. In addition, as shown in (b) and (c), the cross section of the information line (4) may be a convex or concave shape only of the first optically changeable layer (2), but it is preferable that the base material (1) at the location where the information line (4) is formed also has a convex or concave shape corresponding to the convex or concave shape formed in the first optically changeable layer (2) as shown in (d) and (e), since this has a high tamper-proof effect.

When the information image (4) is formed in a convex shape, its height depends on the image width of the information image (4), but is preferably 20 μm to 30 μm from the surface of the substrate. When the information image (4) is formed in a concave shape, it is preferably recessed 20 μm to 30 μm from the surface of the substrate. However, the present invention is not limited to these values, and can be set as appropriate.

The length of the reference line (H1) shown in FIG. 4 is set appropriately according to the size of the image (3) and the distance between the image (3) and the viewer, but it is preferable to set it within the range of 0.5 to 65 mm. The image (3) of the present invention is an image that can be viewed stereoscopically by using binocular parallax. Therefore, it must be kept to 65 mm or less, which is the distance between the eyes of an average human being. Also, in order to create an appropriate sense of perspective that everyone can feel, it must be formed at a specified distance of 0.5 mm or more. Therefore, by setting the length of the reference line (H1) within the above-mentioned range, it becomes easier to view the image (3) by binocular parallax.

When the image (3) is used in a security product or the like, it is preferable that the length of the reference line (H1) is short, since a smaller image is more difficult to tamper with and provides better protection against counterfeiting.

In addition, image (3) is not limited to the character shape described above, and may be meaningful information such as a circle, ellipse, star, polygon, number, character, line, or animal or plant, as long as it is possible to arrange multiple information lines (4), and is not particularly limited. Figure 7 is a plan view showing other shapes of image (3). Image (3) can also be a circle as shown in Figure 7(a), the character shape "A" as shown in Figure 7(b), or a face shape as shown in Figure 7(c). In Figures 7(a), 7(b), and 7(c), element areas (3E) refer to each part that makes up image (3), as shown by the thick lines, and are appropriately formed so that image (3) can be viewed stereoscopically.

Preferably, the virtual line (J) connecting the centers of the reference lines (H1) of the multiple information lines (4) forming the image (3) is one line within one element area (3E).

For example, in FIG. 7(a), there is only one imaginary line (J) connecting the centers of the reference lines (H1) of the multiple information lines (4) that form the image (3). Therefore, the image (3) is composed of one element area (3E).

7B, when the information lines (4) forming the image (3) are arranged from the lower side of the element area (3E ₁ ), the arrangement of the information lines (4) is disrupted in some places. By dividing the disrupted arrangement as shown in the element area (3E ₂ ), the virtual line (J) connecting the centers of the reference lines (H1) in each element area (3E) becomes one, and the image (3) becomes an image (3) that can be viewed stereoscopically.

In addition, it is also possible to arrange the information lines (4) in different directions for each of the multiple element regions (3E).

For example, in the image (3) shown in FIG. 7(c), in the element areas (3E) of the eyes, nose, and mouth, the reference lines of the information image line (H1) within each element area (3E) are all arranged in a straight line direction, but it is also possible to arrange the eyes in the direction of _X11 ( _X11 ), the nose in the direction of _X12 ( _X12 ), and the mouth in the direction of _X13 ( _X13 ), with the direction of _X11 ( _X11 ), the direction of _X12 ( _X12 ), and the direction of _X13 ( _X13 ) being mutually different directions.

Also, as explained in FIG. 4, the reference line (H1) of the information image line (4) of the image (3) can be in different directions within one element area (3E).

For example, in the image (3) shown in FIG. 7(c), in the element area (3E) of the eyes, nose, and mouth, the reference line (H1) of the information image (4) for the eyes can be positioned in a different direction as described above in FIG. 4, while the reference line (H1) for the nose and mouth can be positioned in the same direction as described above in FIG. 3.

Element regions (3E) in which the reference lines (H1) are arranged in the same direction and element regions (3E) in which the reference lines (H1) are arranged in different directions are dynamically viewed in different directions as the observation angle changes. Thus, in FIG. 7(c), the nose and mouth are dynamically viewed in the same direction, but the eyes are dynamically viewed in a different direction from the nose and mouth, and image (3) is dynamically viewed in a more complex manner.

You can also select the line configurations described in Patent Nos. 5,799,431, 6,097,994, 6,583,632, and 6,061,192, which were previously filed by the applicant.

Image (a1) in Figure 8 shows an image illustrating the invention described in Patent No. 6,583,632. In this image (a1), the information lines (4) have a starting point (U), a vertex (T), and an end point (D), and the ratio of the lines from the starting point to the vertex and from the vertex to the end point is the same for multiple information lines (4), and the original image shown in Figure 8 (a2) is viewed three-dimensionally and dynamically.

In addition, Patent No. 6583632 states that an image (3) may be formed from a circular information image (4) by connecting the start point (U) and end point (D) of the arc of the information image (4a) and the information image (4b) shown in FIG. 8 (b1) and having two vertices (T) point-symmetrically from the center of the reference line (H1) of the information image (4a). As shown in FIG. 8 (b1), the circular information image (4) of the present invention may be formed by arranging an information image (4a) whose vertex (T) is above the reference line (H1) connecting the start point (U) and end point (D) and an inverted arc-shaped information image (4b) whose vertex (T) is below the reference line (H1) by inverting the reference line (H1) to form a circular information image (4).

In the circular information line (4) of FIG. 8(b1), the reference line (H1) is the entire diameter of the circle, but the angle (θ1) between the rising line (H2) of the information line (4a) and the reference line (H1) and the angle (θ2) between the falling line (H3) of the information line (4a) and the reference line (H1) make an ellipse, but in the present invention, this also becomes a circular information line (4).

Figure 8(b2) shows an image (3) formed by arranging multiple circular information lines (4) consisting of this arc-shaped information line (4a) and an inverted arc-shaped information line (4b). When Figure 8(b2) is observed from a specified observation angle, the image seen is Figure 8(b3). Figure 8(b3) shows two circles, which are three-dimensional images (7), that can be seen with parts of them overlapping. If the information line (4) is circular, the starting point (U), apex (T), and end point (D) cannot be found from the information line (4), but the three-dimensional image (7) can be dynamically seen, just like image (3) consisting of arc-shaped information lines (4).

In FIG. 8(b1), the circular information image (4) is formed by connecting the start point (U) and the end point (D) of the arc-shaped information image (4a) and the inverted arc-shaped information image (4b). However, it is not necessary to connect the start point (U) and the end point (D). As shown in FIG. 8(b4), the arc-shaped information images (4a, 4b) may be formed slightly apart. In the circular information image (4), two arc-shaped information images (4a, 4b) are arranged and formed, so that the reflected light from the light source that the observer can see is two, the arc-shaped information image (4a) with the apex (T) on the upper side and the arc-shaped information image (4b) with the apex (T) on the lower side. Therefore, the image that is formed is formed at these two points, and when the observation angle of the formed image formation area (5) is changed, the two images can be seen to rotate on a circular circumferential orbit.

The shape shown in Fig. 8(b4) has a break in part (two places) of the circular information image (4) shown in Fig. 8(c), and since a slight break produces the same effect as the image formed with the circular information image (4) in Fig. 8(c), that is, the image moves along a circular orbit and can be visually recognized, it can be used as the circular information image (4) of the present invention. If the distance between the information images due to this break is long, it will naturally become the arc-shaped information image (4a, 4b) of the present invention.

The two images formed by arranging an arc-shaped information line (4a) whose vertex (T) is above the reference line (H1) connecting the starting point (U) and the end point (D) and an arc-shaped information line (4b) whose vertex (T) is below the reference line (H1) connecting the starting point (U) and the end point (D) can be seen as one in front and the other in the back when viewed moving on the information line (4), which gives a sense of depth and creates an even more three-dimensional effect. The three-dimensional effect caused by this sense of depth can also be achieved by forming the circular information line (4) shown in Figure 8 (b1).

As shown in Fig. 8(b5), the circular information line (4) of Fig. 8(b4) may be further shifted horizontally. In this case, the information line (4) is not circular, but is an arc-shaped information line (4a) whose apex (T) is above the reference line (H1) connecting the start point (U) and the end point (D), and an arc-shaped information line (4b) whose apex (T) is below the reference line (H1) connecting the start point (U) and the end point (D) are shifted, so that the effect is a three-dimensional effect with a sense of depth.

Image (a1) in Figure 9 shows the image illustrating the invention described in Patent No. 6097994, image (a2) shows an enlarged view of the area surrounded by the dotted line in image (a1), and (a3) shows the original image that is visible when observing image (a1). Image (a1) in Figure 9 is created by compressing image (a3) in one direction in Figure 9, compressing multiple images arranged in multiple directions, overlaying them, extracting only the overlapping image portions, and forming the extracted image on a substrate.

Figure 9 (b1) shows an image illustrating the invention described in Patent No. 6061192, and Figure 9 (b2) shows the original image that is visible when observing image (b1). Image (b1) has a plurality of minute information lines (4) arranged in a matrix, and the minute information lines (4) are a collection of parts that make up the original image shown in Figure 9 (b2).

By forming these image line configurations with image lines having a concave or convex cross section on the first optical change layer (2) and the substrate (1), the portion formed on the first optical change layer (2) has a three-dimensional and dynamic effect, and the substrate (1) and the first optical change layer (2) can be given the role of a tally. However, even if the image (c1) straddles the substrate (1) and the first optical change layer (2), if the information image line (4) that constitutes the image (c1) is not formed across the first optical change layer (2) and the substrate (1), the effect as a tally is weak. Also, in the configuration of the information image line (4) of the image (b1), even if the image (b1) straddles the substrate (1) and the first optical change layer (2), in the first embodiment, since the image (b1) is a collection of minute information image lines (4), the visibility of the information image line (4) formed on the substrate (1) is only due to the shadow caused by the unevenness, so the effect as a tally is weak. However, in the second and third embodiments described below, even if the image (a1) and image (b1) have the above configuration, the substrate (1) and the second optically changeable layer (6) have brilliance, so the three-dimensional image (7) appears across the first optically changeable layer, the substrate (1), and the second optically changeable layer (6). This provides an effect as a tally seal.

(Regarding the position of the image)
As shown in Fig. 1 and Fig. 3, the image (3) is formed by deforming the substrate (1) and the first optically changeable layer (2) into a concave or convex shape so as to straddle the substrate (1) and the first optically changeable layer (2). There is no particular limitation on the position as long as the image (3) straddles the substrate (1) and the first optically changeable layer (2), and it may be set appropriately. However, from the viewpoint of preventing peeling of the first optically changeable layer (2), which is the subject of the present invention, if more images (3) are formed on the first optically changeable layer, the unevenness of the information image (4) formed on the first optically changeable layer is more likely to be deformed when the first optically changeable layer is intentionally peeled off. Therefore, it is preferable that the image (3) is formed in the first optically changeable layer (1) in 50% or more of the multiple information image lines (4).

In addition, if the substrate (1) or the substrate surface does not have a glossy property, the three-dimensional image (7) cannot be seen if most of the image (3) is formed on the substrate (1). Therefore, if the substrate (1) or the substrate surface does not have a glossy property, it is preferable that the position at which the image (3) is formed is such that 80% to 90% of the image (3) is formed on the first optically change layer (2), since the three-dimensional image (7) can be observed.

(Image Forming Method)
Next, a method for forming the information image 4 will be described. The information image 4 is formed by forming the base material 1 and the first optically variable layer 2 into a concave or convex shape.

One method of forming the information line (4) is to use a known processing machine capable of embossing the glossy base material (2) to give it unevenness to match the shape of the information line (4). In this case, it is preferable to also deform the base material underneath the first optically variable layer (2) since this increases the difficulty of peeling off the first optically variable layer (2) for counterfeit purposes and attaching a different glossy optically variable layer.

In addition, at the same time that the first optically changeable layer (2) is thermocompressed using a known foil stamping machine, the first optically changeable layer (2) and the image (3) may be formed on the substrate (1) using an embossing mold on which the image (3) is formed.

(Principle of stereoscopic image creation)
Next, the principle of appearance of the stereoscopic image (7) that appears when the image (3) is viewed with the naked eye will be explained.

Figure 12(a) is a plan view showing an image (3), in which a first optically changeable layer (2) is formed on a substrate (1), and a plurality of information lines (4) are formed on the substrate (1) in a first direction (X1) by embossing or the like to form an image (3) in the shape of the letter "N". Figure 12(b) shows a three-dimensional image (7) that appears when the image (3) is observed by setting an appropriate light source position and observation angle. Note that in the present invention, it is essential that the image (3) straddles the substrate (1) and the optically changeable layer (2), but in order to explain the principle of the appearance of the three-dimensional image (7), it is easier to explain if the entire image (3) has brilliance, so this form will be used.

The observation angles of image (3) in Figure 12 will be explained using Figure 13. Figure 13 is a diagram showing the observation angles (E1 and E2) for observing the substrate (1) to which image (3) is applied.

In general, when the substrate (2), the light source (Q) in a fixed position, and the viewpoint are in the positional relationship shown in FIG. 13(a), the observation is made from a first observation angle (E1), and when they are in the positional relationship shown in FIG. 13(b), the observation is made from a second observation angle (E2).

The first observation angle (E1) is the observation angle at which the information image (4) shows no change in brilliance when exposed to incident light from a fixed-position light source (Q), and the range of the observation angle (E1) is illustrated as the diffuse reflection region (θ3). For example, in the diffuse reflection region (θ3), the information image (4) cannot be seen to reflect the incident light from the light source (Q). Therefore, the information image (4) reflects light that is less than a predetermined amount of reflected light, and is seen by the naked eye as an image with no change in brilliance.

The second observation angle (E2) is the observation angle at which the information image (4) is visually perceived as having a change in brilliance in response to the incident light from the light source (Q) in a fixed position, and this area is illustrated as the specular reflection area (θ4). In the specular reflection area (θ4), the reflection of the incident light from the light source (Q) can be visually perceived. Therefore, the information image (4) has a reflected light amount equal to or greater than a predetermined amount, and is visually perceived by the naked eye as an image having a change in brilliance.

The first observation angle (E1) and the second observation angle (E2) are not limited to the specular reflection area (θ4) and the diffuse reflection area (θ3) because the positional relationship between the substrate (2), the light source (Q), and the starting point changes due to the first optically changeable layer (2) that forms the information image line (4).

Figure 14 is a schematic diagram showing the principle of visibility of the information image (4) at the second observation angle (E2). As shown in Figure 14 (a), at the second observation angle (E2), the shiny material forming the information image (4) reflects the incident light from the light source (Q).

When the information image (4) has a concave or convex shape relative to the substrate (1), the reflected light (V1, V2, V3, V4, and V5) from the light source (Q) is reflected in multiple directions rather than in one direction.

Because the viewing angle of the observer's left eye (L) is θL, the left eye (L) sees the reflected light (V1 and V2) that is within the viewing angle θL. On the other hand, the reflected light (V3, V4, and V5) is not seen because it is outside the range of the viewing angle θL. Therefore, as shown in FIG. 14(b), the information image (4) is seen by the observer's left eye (L) as having brilliance in the dotted line portion on the left side (U) of the drawing, which is within the viewing angle θL, but as the solid line portion on the right side (D) of the drawing, which is outside the viewing angle θL, is seen as an image that does not have brilliance.

On the other hand, the viewing angle of the observer's right eye (R) is θR, so the right eye (R) sees the reflected light (V4 and V5) that is within the viewing angle θR. On the other hand, the reflected light (V1, V2, and V3) is not seen because it is outside the range of the viewing angle θR. Therefore, as shown in FIG. 14(c), the dotted line portion on the right side (D) of the drawing, which is within the viewing angle θR, of the information image (4) is seen as having brilliance by the observer's right eye (R), but the solid line portion on the left side (U) of the drawing, which is outside the viewing angle θR, is seen as an image that does not have brilliance.

The portion of the information image (4) that is perceived as having brilliance by the left eye (L) shown in FIG. 14(b) and the portion of the information image (4) that is perceived as having brilliance by the right eye (R) shown in FIG. 14(c) are perceived as images that have a phase difference between the left and right sides of the straight line connecting the left (U) side of the drawing and the right (D) side of the drawing. Therefore, even if multiple identical images are not formed side by side, the observer will see both information images (4) due to binocular parallax, as shown in FIG. 14(d).

In Figure 14, a single information line (4) is shown, but Figure 15 shows an image (3) formed by multiple information lines (4).

Figure 15 (a1) is a plan view showing an image (3L) viewed by the observer's left eye (L), and Figure 15 (a2) is an enlarged view of a portion of Figure 15 (a1). As shown in Figure 15 (a2), at the second observation angle (E2), the dotted line portion of the information image (4) is viewed as having brilliance by the observer's left eye (L). On the other hand, the solid line portion in Figure 15 (a2) is viewed as an image without brilliance. Thus, an image (3L) consisting of multiple information images (4) in which the dotted line portions have brilliance and the solid line portions have no brilliance is viewed.

Figure 15 (b1) is a plan view showing an image (3) viewed by the observer's right eye (R), and Figure 15 (b2) is an enlarged view of a portion of Figure 15 (b1). As shown in Figure 15 (b2), at the second observation angle (E2), the dotted line portion of the information image (4) is viewed as having brilliance by the observer's right eye (R). On the other hand, the solid line portion in Figure 15 (b2) is viewed as an image without brilliance. Thus, an image (3R) consisting of multiple information images (4) in which the dotted line portions have brilliance and the solid line portions have no brilliance is viewed.

Fig. 15(c1) is a plan view showing a stereoscopic image (7) viewed by both eyes (L, R) of a viewer, and Fig. 15(c2) is an enlarged view of a portion of Fig. 15(c1). As described above, at the second observation angle (E2), the image (3L) shown in Fig. 15(a1) is viewed by the viewer's left eye (L), and the image (3R) shown in Fig. 15(b1) is viewed by the right eye (R).

As mentioned above, the information line (4) viewed with the left eye (L) and the information line (4) viewed with the right eye are viewed as lines having a phase difference with respect to the reference line (H1), which is a straight line connecting the starting point (U) and the ending point (D). Therefore, in the image (3) consisting of multiple information lines (4), the image (3L) observed with the left eye and the image (3R) observed with the right eye have different phases, and due to binocular parallax, the viewer views the image (3) as a stereoscopic image (7), as shown in FIG. 15 (c1).

Furthermore, by changing the observation angle, it is possible to dynamically view the first image (3) in accordance with the change in the observation angle. Next, the principle by which the stereoscopic image (7) is dynamically viewed will be explained.

Figure 16(a) is a schematic diagram showing the change in observation angle relative to the substrate (1) in the image (3) shown in Figure 12, and Figures 16(b1) and 16(b2) are a plan view and an enlarged view showing the stereoscopic image (7) viewed in Figure 16(a).

As shown in Fig. 16(a), in the specular reflection region (θ4) where the information image (4) is visually recognized as a glittering image, when the observation angle with respect to the substrate (1) is continuously changed from the observation angle ₂₁ ( _E21 ) to the observation angle ₂₂ ( _E22 ), the position of the information image (4) reflecting the incident light from the light source (Q) gradually changes from the start point side to the end point side with the change in the observation angle. As a result, the glittering portion of the first information image (4), shown by the dotted line in Fig. 16(b2), is visually recognized as continuously moving in the direction of the arrow shown in Fig. 16(b2).

For example, when the observation angle is continuously changed from the _21st observation angle ( _E21 ) to the _22nd observation angle ( _E22 ), the stereoscopic image (7) is perceived as moving from right to left, and conversely, when the observation angle is continuously changed from the _22nd observation angle ( _E22 ) to the _21st observation angle ( _E21 ), the stereoscopic image (7) is perceived as moving from left to right. Note that the maximum width (amount of movement) of the stereoscopic image (7) moving left and right is the same as the amount of change in the shining portion of the information image (4), and therefore the stereoscopic image (7) moves left and right within the same range as the length of the reference line (H1).

When observing the image (3), the line connecting the left and right viewpoints and the straight line connecting the start point (U) of the information line (4) and the end point (D) of the information line (5) are approximately parallel to each other, as shown in FIG. 14(a), making it possible to view the information line (4) and the three-dimensional image (7) three-dimensionally. Therefore, when observing, the anti-counterfeiting medium (S1) and/or the viewpoint are adjusted so that the line (G) connecting the left and right viewpoints and the straight line (H1) connecting the start point (U) of the information line (4) and the end point (D) of the information line (5) are approximately parallel to each other.

The above is the principle by which the three-dimensional image (7) appears when it is formed on an optically variable layer in common in the present invention.

(Effects of the invention in the first embodiment)
In the first embodiment, when the anti-counterfeiting medium (S1) is observed from different observation angles, a dynamic and three-dimensional stereoscopic image (7) is observed on the first optically change layer, and a portion of the image (3) that does not have a three-dimensional and dynamic effect is visible on the substrate (1).

By visually recognizing the three-dimensional image (7) on the first optically changeable layer (2), the image (3) is more closely observed than when normal uneven lines are arranged like a tally seal, and the counterfeit prevention effect is improved by increasing the caution when using the counterfeit prevention medium (S1). Furthermore, if the first optically changeable layer is peeled off for the purpose of counterfeiting and reused, the first optically changeable layer is deformed by the peeling force, and the information lines (4) are also deformed, so that the three-dimensional image (7) cannot be reproduced even if the peeled first optically changeable layer is reattached. Furthermore, when the first optically changeable layer is peeled off and another OVD foil or metal foil is attached, the information lines (4) are not present and the three-dimensional image (7) is not manifested, so tampering can be detected. In addition, although it is possible to emboss information lines (4) on items to which OVD foil or metal foil different from the genuine article has been affixed later, it is difficult to seamlessly match the information lines (4) formed on the base material (1) with the counterfeit information lines (4) that have been added later, making the tampering obvious.

Second Embodiment
10 is a diagram showing the configuration of a counterfeit prevention medium (S2). The difference from the first embodiment is that the base material (1b) has a glossy property.

For example, a material having a glossy property, such as a high-gloss plastic, can be selected as the substrate (1b). In this case, the glossiness needs to be present at least in the image forming area (5).

Other than the substrate (1), the first optically changeable layer (2), the structure of the image (3), the method of applying it, and the principle of the observation method are the same as in the first embodiment, so explanations are omitted.

(Effects of the Invention in the Second Embodiment)
The second embodiment is characterized in that the substrate (1) has a lustrous property, which solves the problem in the first embodiment where the information lines (4) applied to the substrate (1) do not have a lustrous property, and therefore the three-dimensional image (7) could only be viewed within the range of the image forming area (5a) formed in the first optically change layer (2).

The glittering nature of the substrate (1) allows the image (3) applied to the substrate (1) and the image (3) applied to the first optically changeable layer (2) to be integrated, and a three-dimensional image (7) can be viewed across the substrate and the first optically changeable layer with a dynamic and three-dimensional effect.

Compared to the first embodiment, this effect makes people who use the anti-counterfeiting medium (S2) more careful, resulting in a higher anti-counterfeiting effect. Even if the first optically variable layer (2) is peeled off from the anti-counterfeiting medium (S2) for the purpose of counterfeiting, an OVD foil or metal foil different from the genuine one is affixed, and then an information line (4) is added by embossing, if the information line (4) on the base material does not exactly match the later embossed line, a change will occur in the appearance of the three-dimensional image (7). This makes it easy to confirm tampering. It is also difficult to match the information line (4) on the base material (1) with an embossed pattern to be counterfeited later.

Third Embodiment
FIG. 11 is a diagram showing a counterfeit prevention medium (S3). In the counterfeit prevention medium (S3), a first optically variable layer (2) is present in a part of a substrate (1), and a second optically variable layer (6) is also present. An image forming area (5) for forming an image (3) is present in a position spanning the first optically variable layer (2) and the second optically variable layer (6). The image forming area (5) includes an image forming area (5a) in the first optically variable layer (2) and an image forming area (5c) in the second optically variable layer, and an image (3) is formed so as to span the image forming area (5a) and the image forming area (5c). The rest of the configuration of the substrate (1), the first optically variable layer (2), and the image (3) are the same. Therefore, the configuration of the second optically variable layer (6) will be described.

The second optically variable layer (6) is formed by applying a glossy ink or varnish to the substrate (1). One example of a method for imparting glossiness, particularly light-dark flip-flop properties, can be achieved easily by printing using a high-gloss ink resin or an ink that contains a metallic pigment mixed into the ink.

Examples of inks with color flip-flop properties include pearl ink, liquid crystal ink, OVI, and CSI (Color Shifting Ink). While most inks have an object color, iridescent pearl ink is colorless and transparent. For example, red iridescent pearl ink is colorless and transparent under diffuse reflected light, but emits a red interference color under specular reflected light. Inks with color flip-flop properties like this change hue under specular reflected light.

The method of forming the second optically changeable layer (6) is not limited to ink or varnish, and it may be formed with OVD foil, metal foil, or a film having a glossy finish, as with the first optically changeable layer (2). However, forming the second optically changeable layer (6) with ink or varnish is preferable, since it prevents the second optically changeable layer from peeling off and ensures that the information lines (4) formed on the second optically changeable layer (6) remain on the substrate.

There are no particular limitations on the shape and area of the second optically variable layer (6) and it can be formed appropriately on the counterfeit prevention medium (S3). The second optically variable layer (6) is formed in a position that includes the image formation area (5c).

(Effects of the Invention in the Third Embodiment)
The effect of the invention in the third embodiment is that, due to the brilliance of the second optical change layer (6), the image (3) imparted to the second optical change layer (6) and the image (3) imparted to the first optical change layer (2) become integrated, and a three-dimensional image (7) can be viewed dynamically and with a three-dimensional effect across the second optical change layer and the first optical change layer.

As a result of this effect, as in the second embodiment, the person using the anti-counterfeiting medium (S1) will be more careful than in the first embodiment, and as a result, the anti-counterfeiting effect will be enhanced. And even if the first optically variable layer (2) is peeled off from the anti-counterfeiting medium (S3), an OVD foil or metal foil different from the genuine one is affixed, and an information image (4) is formed by later embossing, if the information image (4) on the base material does not exactly match the later embossed image, a change will occur in the appearance of the three-dimensional image (7), making it easy to confirm tampering, and it will be difficult to match the information image (4) on the base material (1) with the embossed pattern to be counterfeited later.

The present invention will be described in more detail below using Example 1, but the present invention is not limited thereto. As Example 1, a counterfeit prevention medium (S3) shown in FIG. 11 in the third embodiment was produced. The substrate (2) was coated paper.

First, the pearl ink shown in Table 1 was used to print on the substrate (2) using a known screen printer to form the second optically variable layer (6) shown in FIG. 11. The pearl ink shown in Table 1 is semi-transparent at the first observation angle (E1) and exhibits golden interference light at the second observation angle (E2). If the step of applying this ink is omitted, the counterfeit prevention medium (S1) shown in FIG. 1, described in the first embodiment, will be obtained.

Table 1

Next, as the first optically changeable layer, an OVD foil (manufactured by Toppan Printing) was attached to the substrate (1) in a position adjacent to the second optically changeable layer (6) by pressing it with a hot stamping device (manufactured by Navitas) at 120°C for 1 second.

After that, an original plate was prepared for applying the image (3) to the substrate (1), the first optically changeable layer (2), and the second optically changeable layer (6). The original plate was prepared by laser processing a stainless steel plate (SUS302) using a laser marker (MD-V9600 manufactured by Keyence) to form an image (3) consisting of an "N"-shaped concave information image line (4) as shown in FIG. 4. When laser processing the information image line (4), image data of the information image line (4) was prepared using a known image processing device, and the image data was then input into the laser marker to process the original plate.

Using the above-mentioned master plate, the substrate (2) was embossed by applying a pressure of 5 MPa at a temperature of 90°C for 30 seconds using a hot press machine (made by Dumbbell) so as to straddle the first optically changeable layer (2) and the second optically changeable layer (6), forming an image (3) and producing an anti-counterfeiting medium (S3).

The information lines (4) are convex arc-shaped lines symmetrical on the left and right sides as shown in Figure 5. The information lines (4) have a line width of 200 μm and are formed in a line pattern with a first pitch (P1) of 400 μm. The length of the reference line (H1) is 2 mm to 4 mm.

At the starting point (U), the angle (θ1) made by the tangent (H2) of the arc-shaped first information line (4) to the reference line (H1) is 45 degrees, and at the end point (D), the angle (θ2) made by the tangent (H3) of the arc-shaped first information line (4) to the reference line (H1) is 45 degrees.

When the counterfeit prevention medium (S3) produced in Example 1 was observed from the first observation angle (E1), the multiple information lines (4) appeared as transparent lines on the second optically changeable layer (6) and were visible as non-glossy lines on the first optically changeable layer. Thus, the image (3) formed by the multiple information lines (4) was visible.

Next, when the counterfeit prevention medium (S3) was observed from a second observation angle (E2), the multiple information lines (4) in the second optical change layer were visible as brilliance lines accompanied by a gold interference color, and the multiple information lines in the first optical change layer (2) were visible as brilliance lines. The information lines (4) visible with the left eye (L) and the information lines (4) visible with the right eye were visible as lines having a phase difference with respect to the reference line (H1), which is a straight line connecting the starting point (U) and the ending point (D), and therefore, at the second observation angle (E2), a stereoscopic image (7) was visible from the image (3) due to binocular parallax.

Furthermore, within the region (θ4) in which the information image (4) is viewed as an image having brilliance, when the observation angle relative to the substrate (2) is continuously changed from the observation angle ₂₁ ( _E21 ) to the observation angle ₂₂ ( _E22 ) shown in FIG. 16, the position at which the incident light from the light source (Q) is reflected in the first information image (4) gradually differs from the starting point side to the end point side as the observation angle changes, and the first image (3) is viewed as moving three-dimensionally and continuously from side to side.

As Example 2, the counterfeit prevention medium (S2) shown in FIG. 10 and described in the second embodiment will be specifically described. A PETG sheet (manufactured by Taihei Chemical Industry Co., Ltd.), which is a plastic substrate, was used as the glossy substrate (1a).

First, an OVD foil (manufactured by Toppan Printing) was attached to the substrate (1a) as the first optically changeable layer (2) using a hot stamping device (manufactured by Navitas) at 120°C for 1 second.

Next, using the same master plate as described in Example 1, an image (3) was formed by embossing the plate across the substrate (1a) and the first optically changeable layer (2) using a press (made by Dumbbell) at 80°C, 2.5 MPa, and 30 seconds to produce an anti-counterfeiting medium (S2).

When the counterfeit prevention medium (S2) produced in Example 2 was observed from the first observation angle (E1), the multiple information lines (4) were visible as non-glossy lines on the substrate (1a) and as non-glossy lines on the first optically change layer (2). Thus, the image (3) formed by the multiple information lines (4) was visible.

Next, when the counterfeit prevention medium (S3) was observed from a second observation angle (E2), the multiple information lines (4) were visually recognized as lustrous lines on the substrate (1a) and the first optically change layer (2). The information lines (4) visible to the left eye (L) and the information lines (4) visible to the right eye were visually recognized as lines having a phase difference with respect to the reference line (H1), which is a straight line connecting the starting point (U) and the ending point (D). Therefore, at the second observation angle (E2), a stereoscopic image (7) was visible from the image (3) due to binocular parallax.

Furthermore, within the region (θ4) in which the information image (4) is viewed as an image having brilliance, when the observation angle relative to the substrate (1) is continuously changed from the observation angle ₂₁ ( _E21 ) to the observation angle ₂₂ ( _E22 ) shown in Figure 16, the position at which the incident light from the light source (Q) is reflected in the first information image (4) gradually changes from the starting point side to the end point side as the observation angle changes, and the three-dimensional image (7) is viewed as moving continuously from left to right.

S1, S2, S3 Counterfeit prevention medium 1 Substrate 1a Glossy substrate 1b Non-glossy substrate 2 First optically variable layer OVD foil 2a Protective layer 2b Diffractive layer 2c Adhesive layer 3 Image 3E Element area 3L Image observed from the viewpoint of the right eye (3)
3R Image observed from the left eye's viewpoint (3)
4. Information Line
5 Image forming area 5a Area 5b where an image (3) is formed on the optical change layer (2) Area 5c where an image (3) is formed on the substrate (1) Area 6 where an image (3) is formed on the second optical change layer (6) Second optical change layer 7 Three-dimensional image P1 First pitch X1 First direction U Starting point T Vertex D End point H1 Reference line H2 Rising line H3 Falling line θ1 Angle θ2 between the rising line (H2) of the information image line (4) and the reference line (H1) Angle J between the falling line (H3) of the information image line (4) and the reference line (H1) Virtual line θ3 connecting the midpoints of the reference lines of multiple information images (4) Diffuse reflection area θ4 where a three-dimensional image (7) cannot be observed Regular reflection area E1 where a three-dimensional image (7) can be observed First observation angle E2 Second observation angle E2 _1st 2nd _1st observation angle E2 _2nd 2nd Observation angle Q of ₂ Light sources v1, v2, v3, v4, v5 Reflected light from light source (Q)

Claims (5)

A counterfeit prevention medium having an image on a part of a substrate, the counterfeit prevention medium being capable of dynamically observing a stereoscopic image depending on an observation angle and binocular parallax when observing the image, the counterfeit prevention medium comprising:
a first optically changeable layer having a light-dark flip-flop property and/or a color flip-flop property is formed on a part of the substrate;
an image forming region for forming the image at a position spanning the first optically variable layer and the base material;
A counterfeit prevention medium, characterized in that the image is formed by arranging arc-shaped information lines having a starting point, a vertex and an end point in a line pattern, and the cross-sectional shape of the information lines is a concave or convex shape. The counterfeit prevention medium according to claim 1, characterized in that the image is formed by arranging a plurality of circular information lines, each of which is made up of the arc-shaped information line and an inverted arc-shaped information line that is inverted with respect to a reference line connecting the start point and end point of the arc-shaped information line. The counterfeit prevention medium according to claim 1 or 2, characterized in that the cross-sectional shape of the substrate is a concave or convex shape corresponding to the information image line. The counterfeit prevention medium according to any one of claims 1 to 3, characterized in that the image forming area in the substrate has light/dark flip-flop properties and/or color flip-flop properties. The counterfeit prevention medium according to any one of claims 1 to 4, characterized in that the image forming area in the substrate has a second optically variable layer having light/dark flip-flop properties and/or color flip-flop properties.

Images