JP5867695B2 - Security medium and authenticity determination method using the same - Google Patents

Description

  The present invention relates to a security medium capable of determining authenticity, in particular, a security medium having a three-dimensional fine structure that cannot be discriminated by direct visual observation, and an authenticity determining method thereof.

  For media that require anti-counterfeiting such as vouchers and ID certificates, it is required to be able to easily authenticate without requiring a special device, while high security that is difficult to duplicate is required. ing.

  Conventionally, there are anti-counterfeit image formations such as pearl ink and holograms that can be easily visually judged, and anti-counterfeit image formations that can authenticate authenticity by embedding a two-dimensional latent image pattern in the printed matter and expressing the latent image with a microlens Are known. In addition, there is also known a technique in which a microlens sheet is adhered on a sheet of a structure having a three-dimensional shape with an adhesive layer, and an enlarged image is expressed by the moire effect.

  Patent Document 1 discloses a display body that displays a composite image by a moire effect generated by superimposing a blazed or binary hologram lens on a display pattern having a diffractive structure.

  Patent Document 2 discloses a security medium in which a microlens and a microscope level structure are combined and viewed by enlarging the microscope level structure with a moire effect.

JP 2009-186544 A Special table 2008-529851 gazette

  The security media disclosed in Patent Literature 1 and Patent Literature 2 are so-called overt security media that can perform authenticity determination by themselves. In such an overt security medium, only the security medium itself is used, and it is possible to determine the authenticity by observing whether or not the image presented on the security medium is a predetermined image.

  For authenticity determination, not only such an overwhelming determination method, but also a covert determination method in which determination is performed using a simple determination tool such as a loupe, and further complicated determination is made using an analysis device or the like. Forensic determination methods to perform are known. According to the covert determination method, only an appraiser who possesses a determination tool for determination can perform authenticity determination, and not only confidentiality in authenticity determination but also suppression of counterfeiting or imitation of a security medium can be suppressed. It becomes possible.

  One of the objects of the present invention is to propose a new security medium using such a covert authenticity determination and an authenticity determination method using the security medium.

Therefore, the security medium according to the present invention is:
A three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a first pitch (w) ;
A microlens array having a microlens array in which a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) is overlaid on the three-dimensional microstructure array, whereby the microlens is located the three-dimensional microstructures at the focal point of, possible the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
W is set so as to satisfy the above condition .

Also, the security medium according to the present invention is:
A flexible sheet having a three-dimensional microstructure array formed in a first region and a microlens array formed in a second region;
The three-dimensional microstructure array includes a plurality of three-dimensional microstructures arranged at a first pitch (w) ,
In the microlens array, a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) ,
Bending said sheet, said be to position the 3-dimensional microstructures in the focal position of the microlens, can the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
W is set so as to satisfy the above condition .

Also, the security medium according to the present invention is:
A first sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a first pitch (w) ;
A second sheet having a microlens array in which a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) ;
The first sheet and the second sheet are bound so as to be openable and closable, and in the closed state, the first sheet and the second sheet are placed on the first sheet so that the three-dimensional microstructure is located at a focal position of the microlens. by the second sheet overlap, Ri the three-dimensional microstructures that are expanded Do observable,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
It is characterized by setting w to satisfy

Also, the security medium according to the present invention is:
A plurality of micromirror lenses having a micromirror lens array arranged at a first pitch (p) ;
A determination sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) is superimposed on the micromirror lens array. the is located the three-dimensional microstructures at the focal point of the micro-mirror lens, it allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
W is set so as to satisfy the above condition .

Also, the security medium according to the present invention is:
A flexible sheet having a three-dimensional microstructure array formed in a first region and a micromirror lens array formed in a second region;
The micromirror lens array includes a plurality of micromirror lenses arranged at a first pitch (p) ,
In the three-dimensional microstructure array, a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) ,
Bending said sheet, said be to position the 3-dimensional microstructures in the focal position of the micro-mirror lens, allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
W is set so as to satisfy the above condition .

Also, the security medium according to the present invention is:
A first sheet having a micromirror lens array in which a plurality of micromirror lenses are arranged at a first pitch (p) ;
A second sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) ;
The first sheet and the second sheet are bound so as to be openable and closable, and in the closed state, the first sheet and the second sheet are placed on the first sheet so that the three-dimensional microstructure is located at the focal position of the micromirror lens. It said second sheet that overlaps, allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
W is set so as to satisfy the above condition .

  The authenticity determination method according to the present invention is characterized in that authenticity determination is performed using any one of the security media described above.

  The present invention provides a security medium having a three-dimensional fine structure array, and in particular, a three-dimensional fine structure array formed on a security medium by overlapping determination sheets on which microlens arrays are formed. It is possible to enlarge and observe. The determination sheet is owned by the authenticator, and it is possible to provide a security medium that enables a covert determination using the determination sheet as a key.

  Furthermore, the present invention provides a security medium in which a three-dimensional microstructure is formed in a first area of a sheet and a microlens array is formed in a second area. In the case of such a configuration, the authenticity determination can be performed using the method of overlapping the microlens array on the three-dimensional microstructure as a determination method. Therefore, the authenticity determination can be performed using the three-dimensional fine structure, the location where the microlens array is formed, and the overlapping method at the time of determination as keys. Furthermore, authenticity determination can be performed by individually observing the three-dimensional fine structure array and the microlens array.

  Furthermore, the present invention provides a security medium in which a three-dimensional microstructure array and a microlens array are formed on each of the first sheet and the second sheet that are bound to be openable and closable. In the case of such a configuration, it is possible to perform authenticity determination by closing the page and overlaying the microphone lens array on the three-dimensional fine structure array and observing the enlarged three-dimensional fine structure. Furthermore, it is possible to determine the authenticity by opening the page and individually observing the three-dimensional microstructure and the microlens array.

  The effects when the three-dimensional fine structure array and the microlens array are used have been described above, but the same effects can be obtained when the three-dimensional fine structure array and the micromirror lens array are used.

The perspective view which shows the utilization form of the security medium based on embodiment of this invention (at the time of isolation | separation) The perspective view which shows the utilization form of the security medium based on embodiment of this invention (at the time of superimposition) The schematic diagram which shows the mode at the time of observation of the security medium (type A) which concerns on embodiment of this invention The figure which shows the arrangement | sequence of the three-dimensional fine structure and micro lens which concern on embodiment of this invention The figure which shows the arrangement | sequence of the three-dimensional microstructure which concerns on other embodiment of this invention, and a micro lens. The figure which shows the real image display principle of the security medium (type A) which concerns on embodiment of this invention. The figure which shows the virtual image display principle of the security medium (type A) which concerns on embodiment of this invention. The schematic diagram which shows the form at the time of observation of the security medium (type B) which concerns on embodiment of this invention The figure which shows the real image display principle of the security medium (type B) which concerns on embodiment of this invention. The figure which shows the virtual image display principle of the security medium (type B) which concerns on embodiment of this invention. The figure which shows the relationship between the pitch of a three-dimensional fine structure at the time of a real image display, and pitch difference The figure which shows the relationship between the pitch of a three-dimensional fine structure at the time of a virtual image display, and pitch difference The figure which shows the cross section of the security medium (Example 1: Type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 2: Type B) which concerns on embodiment of this invention The figure which shows the form of the security medium (Example 3: Type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 3: Type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 4: Type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 5: type B) which concerns on embodiment of this invention The figure which shows the form of the security medium (Example 6: Type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 6: type A) which concerns on embodiment of this invention The figure which shows the cross section of the security medium (Example 7: type A) which concerns on embodiment of this invention

  An embodiment of a security medium according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a security card having a security medium according to an embodiment of the present invention. The security medium is a medium formed on various cards, papers, etc. that require authenticity determination such as credit cards, ID certificates, banknotes, cash vouchers, securities, etc., and may not be easily duplicated. Needed.

  The security medium 5 shown in FIG. 1 is an example provided in a security card 4 such as a credit card. The security medium 5 according to the present embodiment includes a three-dimensional fine structure array 6 in which three-dimensional fine structures are arranged. When authenticity determination is performed, as shown in FIG. 2, the determination sheet 9 is superimposed on the security medium 5 provided in the security card 4. The determination sheet 9 of the present embodiment is provided with a microlens array 7. When authenticity determination is performed, it is true that an image (enlarged three-dimensional microstructure) observed through the microlens array 7 in a state where the determination sheet 9 is superimposed on the security medium 5 is a predetermined image. The security card 4 can be confirmed. In the following description, as shown in FIG. 2, the plate surface of the security card 4 is taken as the XY plane, and the direction perpendicular to the XY plane and viewed by the user is taken as the positive direction of the Z axis.

FIG. 3 shows a state in which the security sheet (type A) according to the embodiment of the present invention is observed, that is, a state in which the determination sheet 9 (microlens array 7) is superimposed on the security medium 5 as shown in FIG. It is a schematic diagram, Comprising: It is the perspective view which expanded a part of the state. The security medium 5 according to the present embodiment includes a three-dimensional microstructure array 6 in which a plurality of three-dimensional microstructures 1 are arranged on a plane parallel to the XY plane. On the other hand, the determination sheet 9 has a microlens array 7 in which a plurality of microlenses 2 are arranged on a plane parallel to the XY plane. The microlens array 7 allows an observer to observe a real or virtual image of the enlarged three-dimensional microstructure 1. This is a technique in which a slight pitch difference is provided between the interval (pitch w) between adjacent three-dimensional microstructures 1 and the interval between adjacent microlenses 2 (pitch p), and the moiré effect generated by the pitch difference is used. It has become.

  FIG. 4 shows an array (three-dimensional microstructure array 6) in the plane parallel to the XY plane of the three-dimensional microstructure 1 shown in FIG. 3 and an array (microlens) in the plane parallel to the XY plane of the microlens 2. An array 7) is shown in FIGS. 3 (a) and 3 (b), respectively. In the present embodiment, the three-dimensional microstructure 1 and the microlenses 2 are both arranged in a lattice pattern. As shown in FIG. 3A, adjacent three-dimensional microstructures 1 are arranged with a pitch w in the X-axis direction and a pitch z in the Y-axis direction. The pitch w and the pitch z may be equidistant. The shape of the three-dimensional microstructure 1 can be an arbitrary shape, but has a circular outer shape with a diameter h for easy understanding of the relationship of the enlargement ratio described later.

  On the other hand, as shown in FIG. 4B, the microlenses 2 are arranged in a lattice like the three-dimensional microstructure 1. The adjacent microlenses 2 are arranged with a pitch p in the X-axis direction and a pitch q in the Y-axis direction. However, the pitch p has a slight difference (pitch difference) with respect to the pitch w of the three-dimensional microstructure 1. The pitch p and the pitch q may also be equidistant. Note that the pitch q of the microlenses 2 is also arranged with a slight difference (pitch difference) from the pitch z of the three-dimensional microstructure 1.

  The microlens 2 is formed to have a size of about several tens to several hundreds of μm. On the other hand, the three-dimensional microstructure 1 enlarged by the microlens 2 is formed smaller than the size of the microlens 2. It is preferable that the three-dimensional microstructure 1 has such a size that it cannot be visually recognized when viewed directly for the sake of confidentiality.

  The arrangement of the three-dimensional fine structure 1 and the microlens 2 is not limited to the lattice arrangement as shown in FIG. 4, but may be an arrangement as shown in FIG. The example of FIG. 5 is an example in which the three-dimensional microstructure 1 and the microlenses 2 are arranged in a turtle shell shape. As shown in FIG. 5A, the three-dimensional microstructures 1 adjacent in the X-axis direction are arranged with a pitch w. The three-dimensional microstructures 1 that are adjacent in the oblique direction are similarly arranged with a pitch w. The microlenses 2 are the same, and as shown in FIG. 5B, the microlenses 2 adjacent in the X-axis direction and the oblique direction are arranged with a pitch p. The security medium of the present embodiment uses the moire effect to superimpose and display an enlarged display image of a plurality of three-dimensional microstructures 1 to the observer. Therefore, the more three-dimensional microstructures 1 and microlenses 2 arranged per unit area, the clearer the display image can be.

  The display principle of the security medium (type A) having the configuration shown in FIG. 3 will be described with reference to FIG. Here, the display principle by the three-dimensional microstructure 1 adjacent in the X-axis direction will be described, but the same display principle is also used for the three-dimensional microstructure 1 adjacent in the Y-axis direction or oblique direction. As a result, the display image can be made clearer.

The type A security medium has a layout in which the lens surface of the microlens 2 is arranged on the side close to the observer side and the three-dimensional microstructure 1 is arranged on the side far from the observer when the authenticity determination is performed. FIG. 6 schematically shows the lens surface formed by the microlens 2, the three-dimensional microstructure 1, and the observed real image.

When authenticity determination is performed, the three-dimensional microstructure 1 is positioned at a substantially focal position of the microlens 1 in the Z-axis direction, that is, the observation direction of the observer. The substantially focal position means a position in a range where the observer can visually recognize the enlarged three-dimensional microstructure 1 and means a position within a range of about 30% with respect to an accurate focal length. The pitch between adjacent microlenses 2 is p, the pitch between adjacent three-dimensional microstructures 1 is w, the diameter of the three-dimensional microstructure 1 is h, and the three-dimensional microstructure from the center position of the radius of curvature of the microlenses 2 The distance to the object 1 is d, and the distance between the real image of the three-dimensional microstructure 1 and the center position of the radius of curvature of the microlens 2 is L. Although the figure shows the state of the chief ray in the ZX plane, the three-dimensional microstructure 1 and its real image are shown in a plane parallel to the XY plane in order to make the enlargement easier to understand. The situation is shown. As described with reference to FIG. 2, the observer can observe the enlarged image of the three-dimensional microstructure 1 by observing the security medium with the positive direction of the Z axis as the observation direction.

  6 is configured when the pitch w of the three-dimensional microstructure 1 is larger than the pitch p of the microlens 2 (w> p). In this case, the three-dimensional microstructure 1 forms an enlarged image by the microlens 2. At a predetermined distance L, a real image is formed by overlapping adjacent enlarged images at the same position or substantially the same position due to the pitch difference (w−p), that is, an image on the observer side with respect to the security medium. Is formed. This utilizes the so-called moire effect, and the observer can observe the enlarged three-dimensional microstructure 1 in a floating state.

The enlargement rate of the three-dimensional microstructure 1 observed in this way is verified. In FIG. 5, the equation (1-1) can be derived from the geometric similarity.
w (L + d) = p / L (1-1)
When formula (1-1) is transformed,
L = dp / (w−p) (1-2)

Similarly, the expression (1-3) can be derived from the geometric similarity.
H = Lh / d (1-3)
When the equation (1-3) is transformed,
L = Hd / h (1-4)

From the formulas (1-2) and (1-4), the magnification α of the observed three-dimensional microstructure 1 can be expressed by the formula (1-5).
α = H / h = p / (w−p) (1-5)

  In the following, numerical examples of the enlargement ratio α and the observed image size C for the security medium of FIG. 6 will be described. In any case, the size h (diameter) of the three-dimensional microstructure 1 is fixed at 90 μm, and the pitch w of the three-dimensional microstructure is fixed at 98.9 μm.

  As can be seen from Table 1, the smaller the pitch difference, the larger the enlargement ratio α and the size of the observation image. It can also be seen that a pitch difference of 1 μm greatly affects the enlargement ratio α. Since it is difficult to manufacture the three-dimensional fine structure 1 and the microlens 2 with precisely different pitch differences, it is difficult to duplicate them and prevent forgery or imitation easily. Become.

  FIG. 7 is a security medium (type A) in which the microlenses 2 are arranged on the viewer side, as in FIG. 6, and the pitch p of the microlenses 2 is larger than the pitch w of the three-dimensional microstructure 1. In this case (p> w). FIG. 7 schematically shows the lens surface formed by the microlens 2, the three-dimensional microstructure 1, and the observed virtual image.

  At the time of authenticity determination, the three-dimensional microstructure 1 is located at a substantially focal position of the microlens 1 in the Z-axis direction, that is, the observation direction of the observer. The substantially focal position means a position in a range where the observer can visually recognize the enlarged three-dimensional microstructure 1 and means a position within a range of about 30% with respect to an accurate focal length. The pitch between adjacent microlenses 2 is p, the pitch between adjacent three-dimensional microstructures 1 is w, the diameter of the three-dimensional microstructure 1 is h, and the three-dimensional microstructure from the center position of the radius of curvature of the microlenses 2 The distance to the object 1 is d, and the distance from the three-dimensional microstructure 1 to the real image is L. As described with reference to FIG. 2, the observer can observe the enlarged image of the three-dimensional microstructure 1 by observing the security medium with the positive direction of the Z axis as the observation direction.

  In this case, the three-dimensional microstructure 1 forms an enlarged image by the microlens 2. At this time, at a position of the predetermined distance L, a virtual image is formed by overlapping adjacent enlarged images at the same position or substantially the same position due to the pitch difference (p−w). That is, an image is formed on the side opposite to the observer with respect to the security medium. An observer can observe the enlarged three-dimensional microstructure 1 in a submerged state.

The enlargement rate of the three-dimensional microstructure 1 observed in this way is verified. In FIG. 7, the equation (2-1) can be derived from the geometric similarity.
w / L = p / (L + d) (2-1)
When the equation (2-1) is transformed,
L = dw / (p−w) (2-2)

Similarly, equation (2-3) can be derived from the geometric similarity.
d / h = (d + L) / H (2-3)
When the equation (2-3) is transformed,
L = d (H / h-1) (2-4)

From the formulas (2-2) and (2-4), the magnification α of the observed three-dimensional microstructure 1 can be expressed by the formula (2-5).
α = H / h = p / (p−w) (2-5)

  In the type A security medium as shown in FIG. 3, three-dimensionally arranged on the opposite side (the side far from the observer side) through the microlenses 2 arranged on the observer side. It is possible to enlarge and observe a real image or a virtual image of a fine structure. The security medium of the present embodiment can adopt not only such a configuration (type A) but also the following configuration (type B).

FIG. 8 is a schematic diagram showing a state of observing the security medium (type B) according to the embodiment of the present invention. The security medium according to the present embodiment includes a micromirror lens array 8 in which a plurality of micromirror lenses 3 are arranged. On the other hand, the determination sheet 9 includes a three-dimensional fine structure array 6. For authenticity determination, the three-dimensional microstructure array 6 is placed on the micromirror lens array 8 on the security medium side, and an enlarged image of the three-dimensional microstructure 1 formed by the light reflected by the micromirror lens array 8 is obtained. It is executed by observing.

  The arrangement of the three-dimensional fine structure 1 (three-dimensional fine structure array 6) and the arrangement of the micromirror lens 3 (micromirror lens array 8) are described in a lattice form as shown in FIGS. It is arranged in a turtle shell shape. The three-dimensional microstructure 1 of this embodiment and the sheet on which it is arranged are constituted by a transparent member. On the other hand, the micromirror lens 3 has a reflecting surface having a convex shape in the positive Z-axis direction, and reflects light incident from the observation direction (the direction from the negative Z-axis side to the positive side). The light reflected by the micromirror lens 3 passes through the three-dimensional microstructure 1 and enlarges and displays the real image or virtual image of the three-dimensional microstructure 1 to the observer.

  FIG. 9 shows a security medium (type B) for executing authenticity determination by positioning the three-dimensional fine structure 1 on the viewer side, and the micromirror lens 3 has a pitch w greater than that of the three-dimensional fine structure 1. This is a configuration when the pitch p is large (p> w). FIG. 9 schematically shows the mirror surface formed by the micromirror lens 3, the three-dimensional microstructure 1, and the observed real image.

  At the time of authenticity determination, the three-dimensional microstructure 1 is positioned at a substantially focal position of the micromirror lens 3 on the Z axis, that is, in the observation direction of the observer. The substantially focal position means a position in a range where the observer can visually recognize the enlarged three-dimensional microstructure 1 and means a position within a range of about 30% with respect to an accurate focal length. The pitch between adjacent micromirror lenses 3 is p, the pitch between adjacent three-dimensional microstructures 1 is w, the diameter of the three-dimensional microstructure 1 is h, and the center position of the radius of curvature of the micromirror lens 3 is three-dimensional. The distance to the fine structure 1 is d, and the distance from the three-dimensional fine structure 1 to its real image is L.

  In this case, the reflected light emitted from the micromirror lens 3 passes through the three-dimensional microstructure 1 to form an enlarged image. At this time, at a position of the predetermined distance L, a real image is formed by overlapping adjacent enlarged images at the same position or substantially the same position due to the pitch difference (p−w). Similarly to the type A security medium, this also uses the moire effect, and the observer can observe the enlarged three-dimensional microstructure 1 in a floating state.

The enlargement rate of the three-dimensional microstructure 1 observed in this way is verified. In FIG. 9, the equation (3-1) can be derived from the geometric similarity.
w / L = p / (L + d) (3-1)
When the equation (2-1) is transformed,
L = dw / (p−w) (3-2)

Similarly, the expression (3-3) can be derived from the geometric similarity.
d / h = (d + L) / H (3-3)
When the equation (2-3) is transformed,
L = d (H / h-1) (3-4)

From the expressions (3-2) and (3-4), the magnification α of the observed three-dimensional microstructure 1 can be expressed by the expression (3-5).
α = H / h = p / (p−w) (3-5)

  On the other hand, FIG. 10 is a security medium (type B) that performs authenticity determination by positioning the three-dimensional microstructure 1 on the viewer side, as in FIG. 9, and is 3 than the pitch p of the micromirror lens 3. This is a configuration when the pitch w of the dimensional fine structure 1 is large (w> p). FIG. 10 schematically shows the mirror surface formed by the micromirror lens 3, the three-dimensional microstructure 1, and the observed virtual image.

  The three-dimensional microstructure 1 is arranged at a substantially focal position of the micromirror lens 3 on the Z axis, that is, in the observation direction of the observer. The substantially focal position means a position in a range where the observer can visually recognize the enlarged three-dimensional microstructure 1 and means a position within a range of about 30% with respect to an accurate focal length. The pitch between adjacent micromirror lens mirrors 3 is p, the pitch between adjacent three-dimensional microstructures 1 is w, the diameter of the three-dimensional microstructure 1 is h, and the center position of the radius of curvature of the micromirror lens mirror 3 is The distance to the three-dimensional microstructure 1 is d, and the distance from the three-dimensional microstructure 1 to the virtual image is L.

  In this case, the reflected light emitted from the micromirror lens 3 is transmitted through the three-dimensional microstructure 1 to form an enlarged image. At a position of the predetermined distance L, a virtual image is formed by overlapping adjacent enlarged images at the same position or substantially the same position due to the pitch difference (w−p). An observer can observe the enlarged three-dimensional microstructure 1 in a submerged state.

The enlargement rate of the three-dimensional microstructure 1 observed in this way is verified. In FIG. 10, the equation (4-1) can be derived from the geometric similarity.
w / L = p / (L−d) (4-1)
When formula (1-1) is transformed,
L = dw (w−p) (4-2)

Similarly, equation (4-3) can be derived from the geometric similarity.
h / d = H / (L−d) (4-3)
When the equation (4-3) is transformed,
L = d (H / h + 1) (4-4)

From the expressions (4-2) and (4-4), the magnification α of the observed three-dimensional microstructure 1 can be expressed by the expression (4-5).
α = H / h = p / (p−w) (4-5)

  For each of the type A and type B security media, we examined the enlargement ratio when w> p and when w <p. Next, when w> p (case 1), when w <p (case) For each of 2), the preferred range of the pitch w of the three-dimensional microstructure will be examined. Here, type A using the microlens 2 is examined, but the same applies to the type B using the micromirror lens 3.

First, an upper limit and a lower limit of the pitch w of the three-dimensional microstructure 1 will be described in the case of w> p (case 1).
When the ratio of the pitch difference (w−p) with respect to the three-dimensional microstructure 1 is A [%],
The pitch difference of the microlens 2 with respect to the three-dimensional microstructure 1 is
w−p = w × A / 100 (5-1)
Can be expressed as Using this pitch difference, the pitch p of the microlens 2 is
p = w (1-A / 100) (5-2)
It can be expressed as.

In case 1, the enlargement ratio α can be expressed by equation (1-5). The three-dimensional microstructure 1 located in the pitch w is observed with the size β, which is the product of the pitch w and the magnification factor α, as the upper limit.
β = w × α = w (p / w−p) (5-3)

Considering that the size β at the time of observation is set to 2000 [μm] (2 [mm]) or more, from equation (5-3), β = w (p / w−p) ≧ 2000 (5-3) '
This relationship is required. Substituting equation (5-2) into equation (5-3) ',
100w / (2000 + w) ≧ A (5-3) ''
It can be seen that the ratio A of the pitch difference (w−p) with respect to the three-dimensional microstructure 1 depends on the pitch w of the three-dimensional microstructure 1.

  FIG. 11 is a graph of (5-3) ″, and the pitch w of the three-dimensional microstructure in the case of w> p (case 1) and the pitch difference (w−p) with respect to the pitch w. FIG. A solid line indicates a value where the size β is exactly 2000 [μm] in (5-3) ″. Below the solid line, in the drawing, in the region with dots, the size β is greater than 2000 [μm].

  The upper limit of the pitch w of the three-dimensional microstructure 1 is preferably set to 300 [μm] or less. When the pitch w of the three-dimensional microstructure 1 is set to 300 [μm] or more, the three-dimensional microstructure 1 disposed in the pitch w can be easily observed visually without using a magnifying means such as a lens. . Therefore, it is preferable to provide the pitch w in a size that cannot be visually observed in order to prevent forgery or imitation. More preferably, the upper limit of the pitch w is set to 100 [μm]. Visual observation can be made more difficult, and counterfeiting and imitation can be further suppressed.

  On the other hand, the pitch p of the microlenses 2 is preferably 300 [μm] or less, and more preferably 100 [μm] or less, like the pitch w of the three-dimensional microstructure 1. The observed real image or virtual image is observed using one microlens 2 as one pixel. When the pitch p is 300 [μm] or more, the pixels become coarse and an observation image with low resolution is formed. On the other hand, when the pitch p is 100 [μm] or less, the pixels are almost invisible and a high-resolution image can be provided.

  The lower limit of the pitch w of the three-dimensional microstructure 1 is preferably 10 [μm]. This is because of the ratio A of the pitch difference (w−p). In the present embodiment, the pitch difference between the three-dimensional microstructure 1 and the microlens 2 is important in terms of enlarging an image using the moire effect. However, it is difficult to adjust the pitch difference ratio A with an accuracy of 0.5% or more. Therefore, the lower limit of the pitch w of the three-dimensional microstructure 1 can be set to 10 [μm], which is a value when the pitch difference ratio A = 0.5 [%] at β = 2000 [μm]. preferable.

Next, an upper limit and a lower limit of the pitch w of the three-dimensional microstructure 1 will be described in the case of w <p (case 2).
When the ratio of the pitch difference (w−p) with respect to the three-dimensional microstructure 1 is A [%],
The pitch difference of the microlens 2 with respect to the three-dimensional microstructure 1 is
p−w = w × A / 100 (6-1)
Can be expressed as Using this pitch difference, the pitch p of the microlens 2 is
p = w (1 + A / 100) (6-2)
It can be expressed as.

In case 2, the enlargement ratio α can be expressed by equation (2-5). The three-dimensional microstructure 1 located in the pitch w is observed with the size β, which is the product of the pitch w and the magnification factor α, as the upper limit.
β = w × α = w (p / p−w) (6-3)

Considering that the size β at the time of observation is set to 2000 [μm] (2 [mm]) or more, from equation (6-3), β = w (p / p−w) ≧ 2000 (6-3) '
This relationship is required. Substituting (6-2) into (6-3) ',
100w / (2000-w) ≧ A (6-3) ''
It can be seen that the ratio A of the pitch difference (p−w) with respect to the three-dimensional microstructure 1 depends on the pitch w of the three-dimensional microstructure 1 as in the case 1.

  FIG. 12 is a graph of (6-3) ″, and the pitch w of the three-dimensional microstructure in the case of w <p (case 2) and the pitch difference (p−w) with respect to the pitch w. FIG. A solid line indicates a value where the size β is exactly 2000 [μm] in (6-3) ″. Below the solid line, in the drawing, in the region with dots, the size β is greater than 2000 [μm].

  As in the case 1, the upper limit of the pitch w of the three-dimensional microstructure 1 is preferably set to 300 [μm] or less from the viewpoint of counterfeiting and counterfeiting. Furthermore, it is preferable to set to 100 [μm].

  Similarly to the case 1, the pitch p of the microlenses 2 is preferably set to a size of 300 [μm] or less, and more preferably set to a size of 100 [μm] or less.

  In the case 2, the lower limit of the pitch w of the three-dimensional microstructure 1 is preferably 10 [μm]. This is because, as in the case of Case 1, it is difficult to adjust the pitch difference ratio A to 0.5% or more. Therefore, the lower limit of the pitch w of the three-dimensional microstructure 1 can be set to 10 [μm], which is a value when the pitch difference ratio A = 0.5 [%] at β = 2000 [μm]. preferable.

  Now, the configuration of the security medium according to the embodiment of the present invention will be described. The security medium of the present embodiment is a type (type A) in which a microlens array is superposed on a three-dimensional fine structure array, or a three-dimensional fine structure array is superposed on a micromirror lens array. Type (type B).

Example 1
FIG. 13 shows a cross-sectional view of an authenticity determination tool composed of a security card 4 having a security medium (type A) and a determination sheet 9. The first embodiment corresponds to the form of the security card 4 and the determination sheet 9 described in FIGS. 1 and 2, and FIG. 13A is in a separated state and corresponds to the state in FIG. 1. FIG. 13B shows a superimposed state, which corresponds to the state of FIG. Each cross-section is a cross-sectional view along the ZX plane between AA ′ shown in FIG.

  The security medium of the present embodiment is configured as a three-dimensional microstructure sheet 10 and is attached as a label to sheets such as banknotes and securities or cards such as credit cards. The manufacturing process of the three-dimensional microstructure sheet 10 will be described below.

  Step 1: A positive resist (PMER P-LA900PM manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on a Si substrate with a film thickness of 20 μm, and is subjected to stepper exposure, development processing, and Al sputtering through a photomask, one 90 μm. A resist original plate is produced in which a concavo-convex pattern having a three-dimensional microstructure 1 having a size of 5 mm (height: 5 μm) is arranged in a 20 mm × 20 mm area at a pitch of 99 μm in the X direction and 99 μm in the Y direction.

  Step 2: A UV curable resin 12 is dropped on the resist original plate produced in Step 1, and a base material 11 made of PET or the like is placed thereon, and then cured by irradiating 365 nm UV (ultraviolet rays) to obtain a resist original plate. A duplicate plate having a three-dimensional microstructure 1 formed on the surface is prepared by peeling from the surface. The base material 11 and the UV curable resin 12 are selected from transparent materials so that they can transmit light during use.

  Step 3: The reflective layer 13 is formed on the surface of the three-dimensional microstructure 1 of the duplicated plate in Step 2. In the present embodiment, the reflective layer 13 is formed on the surface of the three-dimensional microstructure 1 by sputtering about 30 nm of Al (aluminum). The reflective layer 13 is made to be a semi-transmissive type by providing a high-refractive index layer, a thin metal layer, or a multilayer film in addition to a configuration that makes it a complete reflective type by providing a metal layer such as Al. Also good.

  Further, according to the configuration in which the reflective layer 13 is provided on the back surface of the three-dimensional microstructure 1, that is, the side opposite to the observation side, the light incident from the microlens 2 is the UV curable resin 12 on the resist original plate. The image is directly reflected on the surface of the three-dimensional microstructure 1 shaped into the shape, and an enlarged image is presented to the observer. The observer observes the shape of the three-dimensional microstructure 1 at the time of shaping, and can observe a sharp shape with reduced edge rounding and the like.

  Step 4: Using a punching blade, the duplicate plate on which the reflective layer 13 is formed in Step 3 is punched out to 15 mm × 15 mm, and the three-dimensional microstructure sheet 10 is produced.

  In the present embodiment, the UV curable resin (photo curable resin) is used for forming the three-dimensional microstructure 1 as described above, but in addition to this, it is formed using a thermosetting resin or a thermoplastic resin. It is good as well.

  The three-dimensional microstructure sheet 10 produced in such a process is attached to an adherend such as the sheet 31 via the heat seal 61 or the like.

  On the other hand, the determination lens 9 is formed with a microlens 2 shaped by mold processing (hot pressing or the like) on one side of a transparent substrate such as a plastic sheet. The authenticity determination is performed by overlapping the determination sheet 9 on which the microlenses 2 are formed on the sheet 31 on which the three-dimensional microstructure sheet 10 is adhered, as indicated by the arrow in FIG. FIG. 13B shows an overlapped state. In addition, the figure is shown schematically, and since the thickness of the three-dimensional microstructure sheet 10 is actually formed very thin, even if the three-dimensional microstructure sheet 10 is interposed, The determination sheet 9 and the sheet 31 are substantially in contact with each other.

  In the present embodiment, the microlens 2 may be formed on the determination sheet 9 by using a shaping method using a UV curable resin.

In this state, it is possible to observe the enlarged three-dimensional microstructure 1 by positioning the three-dimensional microstructure 1 at a substantially focal position of the microlens 2. Since the three-dimensional microstructure 1 is positioned substantially at the focal position of the microlens 2 when they are stacked, the thickness of the determination sheet 9 and the thickness of the three-dimensional microstructure sheet 10 are determined by the focal length of the microlens 2. It is set with consideration.

(Example 2)
FIG. 14 shows a cross-sectional view of an authenticity determination tool comprising a set of a security card 4 provided with a security medium (type B) and a determination sheet 9. The form shown in the figure is the same as that of the first embodiment, but differs in that the three-dimensional microstructure 1 is enlarged and observed with the reflected light from the micromirror lens 3. FIG. 14A shows the structure of the determination sheet 7 in a separated state and the sheet 31 to which the micromirror lens sheet 20 is attached, and FIG. 14B shows the configuration of the determination sheet 20 and the sheet 31 in an overlapped state. Has been. Hereinafter, the manufacturing process of the micromirror lens sheet 20 will be described.

  Step 1: A positive resist (PMER P-LA900PM manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on a Si substrate with a film thickness of 20 μm, subjected to stepper exposure, development processing, and Al sputtering through a photomask, and is 20 mm × 20 mm. In this area, a master plate of a micromirror lens array arranged in a large number at a pitch of 100 μm in the X direction and 100 μm in the Y direction is manufactured.

  Step 2: A UV curable resin 22 is dropped on the original micromirror lens array produced in Step 1, and a substrate 21 made of PET or the like is placed thereon, and then irradiated with 365 nm UV (ultraviolet rays). By curing and peeling from the resist original plate, a replica plate having the original micromirror lens 3 on the surface is produced.

  Step 3: A reflective layer 23 is formed on the surface of the micromirror lens 3 of the duplicate plate in Step 2. In the present embodiment, the reflective layer 13 is formed on the surface of the three-dimensional microstructure 1 by sputtering about 30 nm of Al (aluminum). As in the above-described embodiments, the reflection layer 13 may be either a complete reflection type or a transflective type.

  Step 4: Using a punching blade, the duplicate plate on which the reflective layer 13 is formed in Step 3 is punched out to 15 mm × 15 mm, and the micromirror lens sheet 20 is produced.

  The micromirror lens sheet 20 produced in such a process is attached to an adherend such as the sheet 31 through the heat seal 61 or the like.

  On the other hand, the determination sheet 9 is formed with the three-dimensional microstructure 1, and this formation is a state in which a duplicate plate serving as the original plate of the three-dimensional microstructure 1 is stacked on the UV curable resin dropped on the sheet. Then, UV light is irradiated to cure the UV curable resin, and the duplicate plate is peeled off. Or it is good also as forming only with UV hardening resin, without using a sheet | seat. As a method for forming the three-dimensional microstructure 1, it is also possible to employ a hot press using a mold.

  By superimposing the determination sheet 9 on the micromirror lens sheet 20 thus manufactured, the three-dimensional microstructure 1 enlarged by the reflected light from the micromirror lens 3 could be observed.

  As described above, in Example 1 and Example 2, by using the determination sheet 9 that is separate from the security medium and the security medium that are configured by the three-dimensional fine structure sheet 10 or the micromirror lens sheet 20, the determination sheet 9 It is possible to determine the authenticity of the security medium using as a key.

In the embodiments described below, a three-dimensional microstructure array 6 and a microlens array 7 or a micromirror lens array are provided on one medium, and the three-dimensional microstructure array 6 and the microlens array 7 (or three-dimensional microstructure) are provided. The object array 6 and the micromirror lens array) are separated and superposed. In such an embodiment, the three-dimensional microstructure 6 and the microlens array 7 can be observed even in a separated state. In the state where the three-dimensional microstructure array 6 and the microlens array 7 are separated, the three-dimensional microstructure array 6 (microlens array 7 or micromirror lens array) to be determined is a true three-dimensional microstructure array. 6 and comparing the color tone and the like, it is possible to determine whether the array is a true three-dimensional microstructure array 6 (microlens array 7 or micromirror lens array). Since the authenticity determination can be performed in the separated state in addition to the superimposed state in this way, the accuracy of the authenticity determination can be improved.

(Example 3)
FIG. 15 is a diagram showing a form of a security medium (type A) according to the embodiment of the present invention. In the present embodiment, a three-dimensional microstructure array 6 is formed on one surface of a flexible sheet 32 such as a banknote, and a microlens array 7 is formed on the other surface. FIG. 15A shows a top view of the banknote 15. In the present embodiment, the three-dimensional microstructure array 6 is arranged in a partial area on the right surface of the banknote 15 (the “first area” in the present invention), and the microlens array 7 ( The “second region” in the present invention is formed.

  The authenticity determination by observing the magnified image is executed by bending the sheet 32 and superimposing the microlens array 7 on the three-dimensional microstructure array 6 as shown in FIG. A true image 15 is determined by observing a predetermined image, that is, an enlarged three-dimensional fine structure 1 in an overlapped state.

  FIG. 16 shows a cross-sectional view of the third embodiment described in FIG. 16A is a cross-sectional view of the sheet 32 that is not bent as shown in FIG. 15A, and FIG. 16B is a view in which the sheet 32 is bent on the three-dimensional microstructure sheet 10. The cross section in the piled-up state is shown. In addition, the manufacturing method of the three-dimensional fine structure sheet | seat 10 and the formation method of the micro lens 2 can be performed by the method similar to Example 1 demonstrated in FIG.

  As shown in FIG. 16A, the three-dimensional microstructure sheet 10 is adhered to one surface of the sheet 32, while the microlens 2 is formed on the other surface. By bending the flexible sheet 32 as shown in FIG. 16B, the portion of the sheet 32 on which the microlenses 2 are formed is superimposed on the three-dimensional microstructure sheet 10 and observed from the microlens 2 side. Thus, the three-dimensional microstructure 1 can be enlarged and observed.

  In the third embodiment, the three-dimensional fine structure array 6 and the microlens array 7 are formed on the same sheet 32, and it is possible to determine the authenticity by overlapping them. The authenticity cannot be determined for a person who does not know the formation position of the array 6 and the microlens array 7 and the surface to be formed. In other words, it is possible to determine the authenticity based on the method of overlapping itself. In the form of FIG. 15, the three-dimensional microstructure array 6 and the microlens array 7 are provided substantially symmetrically, and the authenticity is determined by bending near the center of the sheet 32, but the three-dimensional microstructure array 6 The region and position where the microlens array 7 is provided may be irregular.

  In this embodiment, the three-dimensional microstructure array 6 and the microlens array 7 are formed on different surfaces of the sheet 32. However, the three-dimensional microstructure array 6 and the microlens array 7 are formed on the same surface of the sheet 32. It is good to do. In that case, by changing the way of bending the sheet, the overlapping relationship between the three-dimensional microstructure array 6 and the microlens array 7 as in this embodiment is formed, and the enlarged three-dimensional microstructure 1 is observed. It becomes possible.

Example 4
In Example 3, in order to provide the three-dimensional microstructure 1 on a flexible sheet such as a banknote, the three-dimensional microstructure sheet 10 is attached. However, as shown in FIG. Similarly to the microlens 2, 1 may be configured to be integrated with the sheet 32. Even in such a configuration, it is possible to observe the enlarged three-dimensional microstructure 1 by bending the sheet 32 and positioning the microlens 2 on the three-dimensional microstructure 1.

(Example 5)
The configuration of Example 3 or Example 4 can also be used in Type B, that is, in a mode in which the three-dimensional microstructure 1 is superposed on the micromirror lens 3 for observation. FIG. 18 is a view showing a cross section of the security medium (type B) according to the embodiment of the present invention, and shows the same cross section as FIG. The micromirror lens sheet 20 is stuck on the sheet 32 with a heat seal 61. The method for manufacturing the micromirror lens sheet 20 and the method for forming the three-dimensional microstructure 1 have been described with reference to FIG. The same method as in Example 2 can be used.

  As shown in FIG. 18 (a), the micromirror lens sheet 20 is adhered to a predetermined region (“second region” in the present invention) on one surface of the sheet 32, and the three-dimensional microstructure 1 is formed on the other surface. It is formed in a predetermined region (“first region” in the present invention). By bending the flexible sheet 32 as shown in FIG. 18B, the region of the sheet 32 on which the three-dimensional microstructure 1 is formed overlaps the region on which the micromirror lens sheet 20 is formed. By observing from the dimensional fine structure 1 side, the three-dimensional fine structure 1 can be enlarged and observed by reflected light.

  In the fifth embodiment, the micromirror lens sheet 20 may be integrated with the sheet 32 as in the fourth embodiment. The three-dimensional fine structure array and the micromirror lens array may be provided on the same surface of the sheet 32.

(Example 6)
FIG. 19 is a diagram showing a form of a security medium (type A) according to the embodiment of the present invention. This embodiment is a security medium in which a three-dimensional microstructure array 6 and a microlens array 7 are provided on adjacent sheets (pages) in a booklet, a book, or the like. The embodiment shown in the figure is an example applied to the booklet 16 and is formed by binding a first sheet 33 and a second sheet 34 which are adjacent pages. The first sheet 33 is provided with a three-dimensional microstructure array 6, and the second sheet 34 is provided with a microlens array 7. When the booklet 16 is closed, the microlens array 7 is overlapped on the three-dimensional fine structure array 6 and the three-dimensional fine structure 1 can be enlarged and observed.

  In the present embodiment, since the first sheet 33 and the second sheet 34 are bound, the overlapping position of the three-dimensional microstructure array 6 and the microlens array 7 is limited. Since the three-dimensional microstructure array 6 and the microlens array 7 can be individually observed, it is possible to perform authenticity determination by individual observation in addition to authenticity determination in which enlarged images are observed in an overlapping state.

FIG. 20 shows a cross-sectional view of the sixth embodiment described in FIG. 20A is a cross-sectional view in a state where the second sheet 34 that is a cover page is closed, and FIG. 20B is a cross-sectional view of the three-dimensional microstructure sheet 10 when the second sheet 34 is closed. The cross section in the state which piled up sheet 32 is shown. In addition, the manufacturing method of the three-dimensional fine structure sheet | seat 10 and the formation method of the micro lens 2 can be performed by the method similar to Example 1 demonstrated in FIG.

  As shown in FIG. 20A, the three-dimensional microstructure sheet 10 is attached to the first sheet 33, and the microlens 2 is a second sheet 34 that is a page adjacent to the first sheet. Formed. As shown in FIG. 20B, the second sheet 34 is overlaid on the first sheet 33, that is, by closing the first sheet 33, the portion of the second sheet 34 on which the microlenses 2 are formed is By superimposing on the three-dimensional fine structure sheet 10 and observing from the microlens 2 side, the three-dimensional fine structure 1 can be enlarged and observed.

(Example 7)
The configuration of Example 6 can also be used in Type B, that is, in the form in which the three-dimensional microstructure 1 is superimposed on the micromirror lens 3 and observed. FIG. 21 is a view showing a cross section of the security medium (type B) according to the embodiment of the present invention, and shows the same cross section as FIG. The micromirror lens sheet 20 is stuck on the first sheet 33 with a heat seal 61. The manufacturing method of the micromirror lens sheet 20 and the method of forming the three-dimensional microstructure 1 are shown in FIG. The method can be performed in the same manner as in Example 2 described above.

  As shown in FIG. 21 (a), the micro mirror lens sheet 20 is stuck on the first sheet 33, whereas the three-dimensional microstructure 1 is a page adjacent to the first sheet. It is formed on the second sheet 34. As shown in FIG. 21B, the second sheet 34 is overlapped on the first sheet 33, that is, the first sheet 33 is closed to close the second sheet 34 on which the three-dimensional microstructure 1 is formed. By superimposing the portion on the micromirror lens sheet 20 and observing from the three-dimensional microstructure 1 side, the three-dimensional microstructure 1 can be enlarged and observed by reflected light.

  Note that the present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments also fall within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Three-dimensional fine structure 2 ... Micro lens 3 ... Micro mirror lens 4 ... Security card 5 ... Security medium 6 ... Three-dimensional fine structure array 7 ... Micro lens array 8 ... Micro mirror lens array 9 ... Determination sheet 10 ... 3 Dimensional fine structure sheet 11 ... base material 12 ... UV curable resin 13 ... reflective layer 15 ... bill 16 ... booklet 20 ... micromirror lens sheet 21 ... base material 22 ... UV curable resin 23 ... reflective layer 31, 32 ... sheet 33 ... 1st sheet 34 ... 2nd sheet

Claims (7)

A three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a first pitch (w) ;
A microlens array having a microlens array in which a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) is overlaid on the three-dimensional microstructure array, whereby the microlens is located the three-dimensional microstructures at the focal point of, possible the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy A flexible sheet having a three-dimensional microstructure array formed in a first region and a microlens array formed in a second region;
The three-dimensional microstructure array includes a plurality of three-dimensional microstructures arranged at a first pitch (w) ,
In the microlens array, a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) ,
Bending said sheet, said be to position the 3-dimensional microstructures in the focal position of the microlens, can the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy A first sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a first pitch (w) ;
A second sheet having a microlens array in which a plurality of microlenses are arranged at a second pitch (p) different from the first pitch (w) ;
The first sheet and the second sheet are bound so as to be openable and closable, and in the closed state, the first sheet and the second sheet are placed on the first sheet so that the three-dimensional microstructure is located at a focal position of the microlens. by the second sheet overlap, Ri the three-dimensional microstructures that are expanded Do observable,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy A plurality of micromirror lenses having a micromirror lens array arranged at a first pitch (p) ;
A determination sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) is superimposed on the micromirror lens array. the is located the three-dimensional microstructures at the focal point of the micro-mirror lens, it allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy A flexible sheet having a three-dimensional microstructure array formed in a first region and a micromirror lens array formed in a second region;
The micromirror lens array includes a plurality of micromirror lenses arranged at a first pitch (p) ,
In the three-dimensional microstructure array, a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) ,
Bending said sheet, said be to position the 3-dimensional microstructures in the focal position of the micro-mirror lens, allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy A first sheet having a micromirror lens array in which a plurality of micromirror lenses are arranged at a first pitch (p) ;
A second sheet having a three-dimensional microstructure array in which a plurality of three-dimensional microstructures are arranged at a second pitch (w) different from the first pitch (p) ;
The first sheet and the second sheet are bound so as to be openable and closable, and in the closed state, the first sheet and the second sheet are placed on the first sheet so that the three-dimensional microstructure is located at the focal position of the micromirror lens. It said second sheet that overlaps, allows the three-dimensional microstructures that are expanded observed to Do Ri,
When the ratio of the pitch difference (w−p) to the three-dimensional microstructure is A [%],
If w> p,
100 w / (2000 + w) ≧ A> 0
Set w to satisfy
If w <p,
100w / (2000-w) ≧ A> 0
A security medium characterized by setting w to satisfy An authenticity determination method comprising: performing authenticity determination using the security medium according to any one of claims 1 to 6.

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