JP5994899B2 - Display and labeled goods - Google Patents

Description

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

  Generally, securities such as gift certificates and checks, cards such as credit cards, cash cards and ID cards, and certificates such as passports and licenses must be printed with ordinary printed materials to prevent counterfeiting. The display body which has a different visual effect is affixed. In recent years, the distribution of counterfeit goods has become a social problem for articles other than these. Therefore, the opportunity to apply the same forgery prevention technology to such articles is increasing.

  As a display body having a visual effect different from that of a normal printed material, a display body including a diffraction grating in which a plurality of grooves are arranged is known. For example, the display body can display an image that changes according to the observation condition, or can display a stereoscopic image. Further, the spectral color shining in rainbow colors expressed by the diffraction grating cannot be expressed by a normal printing technique. Therefore, a display body including a diffraction grating is widely used for articles that require anti-counterfeiting measures.

For example, a technique for displaying a pattern by arranging a plurality of diffraction gratings having different groove length directions or different lattice constants (that is, groove pitches) is known (see Patent Document 1). When the relative position of the observer or the light source with respect to the diffraction grating changes, the wavelength of the diffracted light that reaches the eyes of the observer changes. Therefore, when the above configuration is adopted, an image that changes to a rainbow color can be expressed.
In a display body using a diffraction grating, a relief type diffraction grating formed with a plurality of grooves is generally used. The relief type diffraction grating is usually obtained by duplicating from an original plate manufactured using photolithography.

  In Patent Document 1, as a method for producing an original plate of a relief type diffraction grating, a flat substrate coated with a photosensitive resist on one main surface is placed on an XY stage, and the stage is moved under computer control. A method for pattern exposure of a photosensitive resist by irradiating the photosensitive resist with an electron beam is described. In addition, the master of the diffraction grating can be formed using two-beam interference.

  In the manufacture of a relief type diffraction grating, usually, an original plate is first formed by such a method, and a metal stamper is prepared therefrom by a method such as electroforming. Next, using this metal stamper as a matrix, a relief type diffraction grating is duplicated. That is, first, for example, a thermoplastic resin or a photocurable resin is applied on a thin transparent substrate in the form of a film or sheet made of polyethylene terephthalate (PET) or polycarbonate (PC). Next, a metal stamper is brought into close contact with the coating film, and heat or light is applied to the resin layer in this state. After the resin is cured, the metal stamper is peeled from the cured resin to obtain a replica of the relief type diffraction grating.

Generally, this relief type diffraction grating is transparent. Therefore, usually, a metal thin film layer is formed on a resin layer provided with a relief structure by depositing a metal such as aluminum or a dielectric in a single layer or multiple layers by vapor deposition.
Then, the display body obtained in this way is affixed on the base material which consists of paper or a plastic film through an adhesive layer or an adhesion layer, for example. As described above, a display body with anti-counterfeit measures is obtained.

An original plate used for manufacturing a display including a relief type diffraction grating is difficult to manufacture. Further, the transfer of the relief structure from the metal stamper to the resin layer must be performed with high accuracy. That is, high technology is required for manufacturing a display body including a relief type diffraction grating.
However, as a result of the use of display bodies including relief-type diffraction gratings in many articles that require anti-counterfeiting measures, this technology has become widely recognized, and along with this, the occurrence of counterfeit products tends to increase. is there. For this reason, it has become difficult to achieve a sufficient anti-counterfeit effect using a display body that is characterized only by exhibiting rainbow light by diffracted light.

US Pat. No. 5,058,992

  An object of the present invention is to provide a display body that exhibits a characteristic visual effect during transmission observation and exhibits a sufficient anti-counterfeit effect and a labeled article using the display body.

  In order to solve the above-mentioned problem, the display body of the invention according to claim 1 is formed from a laminate in which a light transmission layer is laminated on a metal thin film layer having both light reflectivity and light transmittance. A display body comprising a plurality of convex portions projecting from the metal thin film layer toward the light transmissive layer or a plurality of concave portions recessed from the light transmissive layer toward the metal thin film layer, wherein the convex portion or the concave portion is 200 nm or more and 500 nm or less. A plurality of first interface portions arranged in a lattice pattern at an average center distance, and a relief structure forming layer is formed at the interface portion between the metal thin film layer and the light transmission layer by the first interface portion. The layer thickness on the flat surface of the metal thin film layer is in the range of 30 nm or more and 100 nm or less, and is thicker than the layer thickness of the metal thin film layer on the side surface portion of the convex portion or the concave portion. Depending on the average center-to-center distance for incidence The light source the length of the light, characterized in that emitted as transmitted light on the opposite side.

According to a second aspect of the present invention, in the display body according to the first aspect, the average distance between the centers of the convex portions or the concave portions is different in each of the plurality of first interface portions.
According to a third aspect of the present invention, in the display body according to the second aspect, images such as pictures, characters, symbols, and the like are displayed by a plurality of first interface portions having different average center distances between the convex portions or the concave portions. It is characterized by that.
The display according to a fourth aspect of the present invention is the display according to any one of the first to third aspects, wherein the main wavelength of light transmitted through each of the plurality of first interface portions is four sides of 3 μm to 300 μm. Three or more different first interface portions are regularly arranged adjacent to each other so that the average distance between the centers of the convex portions or concave portions is 200 nm or more and 500 nm or less. It is characterized by that.

The display according to a fifth aspect of the present invention is the display according to the first aspect, wherein the angle (azimuth angle) at which the convex portions or the concave portions are arranged is a rectangle composed of four sides of 3 μm or more and 300 μm or less. The plurality of first interface portions are different from each other.
The labeled article of the invention according to claim 6 is an article in which the display body according to any one of claims 1 to 5 is formed of a light-transmitting base material via a light-transmitting adhesive layer. It is supported by.

According to the first aspect of the present invention, since the convex portions or concave portions of the first interface portion are arranged with an average center distance smaller than the wavelength of visible light, the first interface portion is observed from the light incident side. When the reflected light from the display body is observed, it is perceived as black or dark gray by the antireflection / suppression effect. Further, when the first interface portion is observed from the side opposite to the light incident side, that is, when the transmitted light from the display body is observed, an effect that the first interface portion can be seen through can be obtained. In addition, since the wavelength of the transmitted light changes according to the average center distance between the convex portions or the concave portions, for example, even when the display body is observed with the light from the white light source as the incident light, any of red, blue, green, etc. Can perceive color.
Therefore, according to the first aspect of the invention, it is possible to realize a completely different visual effect when observing the reflected light and when observing the transmitted light, which is realized by printing with ink or a conventional diffraction grating pattern. It can not be performed, and a high anti-counterfeit effect is exhibited, and authenticity determination can be performed reliably.

  According to the second aspect of the invention, when the first interface portion is observed under the reflection condition, any first interface portion appears black or dark gray, while when the first interface portion is observed through transmission, the average of the convex portion or the concave portion is observed. Since the wavelength of light transmitted through the display body changes according to the center-to-center distance, a different color can be observed for each first interface portion. Since the first interface portion perceived in substantially the same color (black or dark gray) in reflection observation can be observed in different colors during transmission observation, a higher forgery prevention effect can be realized.

According to the invention of claim 3, the eye catching effect (the eye-catching effect) can be further enhanced by expressing a specific image with colors of different wavelengths during transmission observation, and the design of the display body It can also improve sex.
According to the invention of claim 4, when observing with the naked eye, the shape of each first interface part and the color due to the transmitted light cannot be perceived, and transmitted light from a plurality of adjacent first interface parts is mixed. It is possible to display a mixed color due to the combination. Therefore, it becomes possible to express many colors, and the improvement of the anti-counterfeit effect and the improvement of the design can be achieved.

According to the fifth aspect of the present invention, when a character with a plurality of minute first interface portions arranged adjacent to each other is observed with the naked eye, each shape of the first interface portions is prevented from being recognized by an observer. can do. In addition, since mixed light transmitted from a plurality of adjacent first interface portions is mixed, it is possible to display a mixed color using light of a plurality of wavelengths, so that the number of colors that can be displayed is increased and the design is improved.
According to the invention which concerns on Claim 6, it is useful for suppression of forgery and unauthorized use of articles | goods by the characteristic visual effect derived from a display body. This visual effect can also provide an aesthetic appearance to the article.

It is a top view of the display body which concerns on the 1st embodiment of this invention. It is sectional drawing along the II-II line of FIG. It is a perspective view which shows an example of the relief structure employable for the display body shown in FIG. It is a top view of the relief structure shown in FIG. It is a perspective view which shows the other example of the relief structure employable for the display body shown in FIG. It is a top view of the relief structure shown in FIG. It is a figure which shows a state when light is irradiated to the surface of a diffraction grating with a large lattice constant. It is a figure which shows a state when light is irradiated to the surface of the diffraction grating with a small lattice constant. It is a figure which shows the behavior of the light which injected into the optical thin film. It is a figure which shows an example in the case of observing the front of the display body shown in FIG. 1 with the reflected light from a display body. It is a figure which shows the other example in the case of observing the front of the display body shown in FIG. 1 with the reflected light from a display body. It is a figure which shows an example in the case of observing the front of the display body shown in FIG. 1 with the transmitted light from a display body. It is a perspective view of the display body which concerns on the 2nd embodiment of this invention. It is a top view which shows an example at the time of arrange | positioning the several 1st interface part shown in FIG. 13 alternately alternately. It is sectional drawing which shows an example of a metal thin film layer. It is a figure which shows the reflective characteristic and the transmission characteristic of light with respect to a metal thin film layer. It is a perspective view which shows an example of a diffraction grating. It is a perspective view which shows an example of a light-scattering structure. It is a top view which shows an example of a labeled article. It is sectional drawing along the XX-XX line of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of a display body according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 and 2, the X1 direction and the Y1 direction are parallel to the display surface of the display body 1 and intersect each other, and the Z1 direction is a direction perpendicular to the X1 direction and the Y1 direction. . Here, as an example, it is assumed that the X1 direction and the Y1 direction are orthogonal to each other.

As shown in FIG. 2, the display body 1 shown in FIG. 1 includes a laminate including a light transmission layer 11 and a metal thin film layer 12. In this embodiment, the light transmission layer 11 side is the front side and the metal thin film layer 12 side is the back side, but the light transmission layer 11 side may be the back side and the metal thin film layer 12 side may be the front side.
The light transmission layer 11 is a layer having high light transmittance with respect to visible light, and is typically formed of a transparent material.

The light transmissive layer 11 includes a light transmissive substrate 111 and a light transmissive resin layer 112, and the light transmissive substrate 111 and the light transmissive resin layer 112 form a laminate. The light transmission layer 11 may have a single layer structure or a multilayer structure of three or more layers.
The light transmissive substrate 111 is formed of a film or sheet that can be handled by itself. As a material of the light transmissive substrate 111, a resin having a light transmissive property such as polycarbonate or polyester can be used, and the light transmissive substrate 111 can be omitted.

The light transmissive resin layer 112 is a layer formed on the light transmissive substrate 111, and a relief structure forming layer for forming the relief structure DS is formed on the surface of the light transmissive resin layer 112. . The relief structure forming layer will be described in detail later.
As a method of forming the light transmissive resin layer 112 on the light transmissive base material 111, for example, a resin is applied on the light transmissive base material 111, and the resin is cured while pressing a stamper on the coating film. A method can be used, and as the resin applied on the light transmissive substrate 111, a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like can be used.

  The metal thin film layer 12 covers the surface of the light transmissive resin layer 112 on which the relief structure DS is provided. The metal thin film layer 12 may cover a part of the surface of the light transmissive resin layer 112 provided with the relief structure DS, or may cover the entire surface provided with the relief structure DS. As the metal thin film layer 12, for example, a metal layer made of a metal material such as aluminum, silver, gold, or an alloy thereof can be used.

  The metal thin film layer 12 can be formed, for example, by a vapor deposition method such as a vacuum evaporation method or a sputtering method. For example, a thin film is formed on the surface of the light transmissive resin layer 112 by a vapor deposition method, and a part of the thin film is dissolved with a chemical or the like, or an adhesion stronger than the adhesion between the light transmissive resin layer 112 and the thin film. The metal thin film layer 12 can be formed by peeling a part of the thin film with an adhesive having strength. When the surface of the light-transmitting resin layer 112 on which the relief structure DS is formed is partially covered with the metal thin film layer 12, the metal thin film layer 12 can also be formed by a vapor deposition method using a mask. Is possible.

  The display body 1 can further include other layers such as an adhesive layer, an adhesive layer, and a resin layer. In this case, it is desirable to form the adhesive layer and the adhesive layer so as to cover the metal thin film layer 12. When the display 1 includes both the light transmission layer 11 and the metal thin film layer 12, the shape of the surface of the metal thin film layer 12 is generally almost the same as the shape of the interface between the light transmission layer 11 and the metal thin film layer 12. Therefore, when the adhesive layer or the adhesive layer is provided as described above, it is possible to prevent the surface of the metal thin film layer 12 from being exposed. Therefore, it is possible to make it difficult to duplicate the relief structure for the purpose of counterfeiting.

When the light transmission layer 11 side is the back side and the metal thin film layer 12 side is the front side, the adhesive layer and the adhesive layer are formed on the light transmission layer 11.
When the display body 1 includes a resin layer, the resin layer is formed on the front side with respect to the laminate of the light transmission layer 11 and the metal thin film layer 12. For example, when the light transmission layer 11 side is the back side and the metal thin film layer 12 side is the front side, if the metal thin film layer 12 is covered with a resin layer, damage to the metal thin film layer 12 can be suppressed, and counterfeiting It is possible to make replication difficult by transferring the intended relief structure. The resin layer is, for example, a hard coat layer intended to prevent the surface of the display body from being scratched during use, an antifouling layer that suppresses the adhesion of dirt, an antistatic layer, and the like.

Next, the 1st interface part provided in a relief structure formation layer is demonstrated.
As described above, the interface between the light transmission layer 11 and the metal thin film layer 12 functions as a reflection surface. This reflecting surface includes the first interface portion 2 shown in FIG. The first interface 2 is a continuous area. In the example shown in FIG. 1, the reflection surface includes only one first interface portion 2, but may include a plurality of first interface portions 2. The first interface portion 2 may occupy the entire surface of the display body 1 or may occupy only a part of the display body 1.

The first interface portion 2 includes a relief structure DS composed of a plurality of convex portions or concave portions. Thus, a plurality of convex portions or concave portions are provided on the surface of the metal thin film layer 12 on the viewer side. Here, the relief structure DS is composed of a plurality of convex portions. The matters described below for the convex portions are the same for the concave portions except that the “height” described for the convex portions should be read as “depth” for the concave portions.
3 is a perspective view showing an example of a relief structure that can be employed in the display body shown in FIGS. 1 and 2, and FIG. 4 is a plan view of the relief structure shown in FIG. FIG. 5 is a perspective view showing another example of the relief structure, and FIG. 6 is a plan view of the relief structure shown in FIG. 3 and 5 show a case where the relief structure is viewed from the light transmission layer side.

  The relief structure DS shown in FIGS. 5 and 6 is different from the relief structure DS shown in FIGS. 3 and 4 in the extending direction of the row formed by the plurality of convex portions PR. That is, the relief structure DS shown in FIGS. 3 and 4 has a plurality of convex portions PR arranged in parallel with the X1 axis and the Y1 axis, whereas the relief structure DS shown in FIGS. 5 and 6 has a plurality of convex portions. The PRs are arranged in parallel with a straight line that intersects the X1 axis and the Y1 axis at an angle of 45 °.

  The relief structure DS shown in FIGS. 3 and 4 or FIGS. 5 and 6 is formed in the first interface portion 2. This relief structure DS includes a plurality of convex portions PR regularly arranged at an average center distance AD of 200 nm to 500 nm. The relief structure DS may be a structure composed of a plurality of convex portions extending in directions other than the directions shown in FIGS. 3 and 4 or FIGS. 5 and 6. Further, the relief structure DS formed in the first interface portion 2 may be a structure in which both convex portions and concave portions coexist.

Each convex part PR of the relief structure DS typically has a tapered shape. Examples of the tapered shape include a semi-spindle shape, a cone shape such as a cone and a pyramid, and a truncated cone shape such as a truncated cone and a truncated pyramid. The side surface of the convex part PR may be composed only of an inclined surface or may be stepped. As will be described later, the tapered shape of the convex part PR is useful for reducing the reflectance of light incident on the relief structure DS. When the light transmissive resin layer 112 is formed using a stamper, the taper shape of the convex portion PR facilitates removal of the cured light transmissive resin layer 112 from the stamper, and contributes to improvement in productivity. . A part of the convex part PR may not have a tapered shape.
As described above, since the projections PR are regularly arranged, the relief structure DS functions as a diffraction grating. Specifically, the relief structure DS shown in FIGS. 3 to 6 functions in substantially the same manner as a diffraction grating in which grooves are arranged as indicated by dotted lines. However, the highly diffracted light emitted from the relief structure DS can only be observed under special conditions.

When illumination light is irradiated to the relief structure DS that can function as a diffraction grating, the relief structure DS emits strong diffracted light in a specific direction with respect to the traveling direction of the illumination light that is incident light. Here, if the grating constant of the diffraction grating is d, the diffraction order of the diffraction grating is m (where m = 0, ± 1, ± 2,...), And the wavelengths of incident light and diffracted light are λ, The emission angle β of the diffracted light can be calculated from the following equation (1) when the light travels in a plane perpendicular to the length direction of the grooves of the diffraction grating.
d = mλ / (sin α−sin β) (1)
In the formula (1), α represents the exit angle of 0th-order diffracted light, that is, transmitted light or specularly reflected light, and the absolute value of α is equal to the incident angle of illumination light. The incident direction of light and the emission direction of specularly reflected light are symmetric with respect to the normal line of the interface provided with the diffraction grating.

  When the diffraction grating is of a reflective type, the exit angle α of transmitted light or regular reflected light is 0 ° or more and less than 90 °. Further, when the illumination light is irradiated to the interface provided with the diffraction grating from an oblique direction, and the angle in the normal direction, that is, two angle ranges with 0 ° as a boundary value, the emission angle β of the diffracted light is A positive value when the exit direction of the diffracted light and the exit direction of the specularly reflected light are within the same angular range, and a negative value when the exit direction of the diffracted light and the incident direction of the illumination light are within the same angular range It is. Hereinafter, an angle range including the emission direction of the specularly reflected light is referred to as a “positive angle range”, and an angle range including the incident direction of the illumination light is referred to as a “negative angle range”.

  When the diffraction grating is observed from the normal direction, the diffracted light contributing to the display is only diffracted light having an exit angle β of 0 °. Therefore, in this case, if the grating constant d of the diffraction grating is larger than the wavelength λ of the diffracted light, there exists a wavelength λ and an incident angle α satisfying the relationship shown in the equation (1). A person can observe diffracted light having a wavelength λ that satisfies the relationship represented by the formula (1).

On the other hand, when the grating constant d of the diffraction grating is smaller than the wavelength λ of the diffracted light, there is no incident angle α that satisfies the relationship expressed by the equation (1). Therefore, in this case, the observer cannot observe the diffracted light.
As is clear from this explanation, the relief structure DS having the small average center distance AD of the projections PR does not emit diffracted light in the normal direction, unlike a normal diffraction grating. Alternatively, the diffracted light emitted from the relief structure DS in the normal direction has only low visibility.

This will be described in more detail with reference to FIGS.
FIG. 7 is a diagram showing a state when light is irradiated on the surface of a diffraction grating having a large lattice constant, and FIG. 8 is a diagram showing a state when light is irradiated on the surface of a diffraction grating having a small lattice constant.
7 and 8, IF indicates the interface on which the diffraction grating GR is formed, and NL indicates the normal line of the interface IF. IL indicates white illumination light composed of light of a plurality of wavelengths, and RL indicates specular reflection light or zero-order diffracted light. Further, DLr, DLg, and DLb respectively indicate first-order diffracted light having wavelengths corresponding to red, green, and blue obtained by spectrally dividing the white illumination light IL.

The interface IF shown in FIG. 7 is provided with a diffraction grating GR having a grating constant larger than the shortest wavelength of visible light, for example, 400 nm. On the other hand, the interface IF shown in FIG. 8 is provided with a diffraction grating GR whose lattice constant is smaller than the shortest wavelength of visible light.
As is clear from the equation (1), when the grating constant d of the diffraction grating is larger than the shortest wavelength of visible light (for example, larger than 400 nm), the illumination light IL is obliquely applied to the interface IF. When irradiated, the diffraction grating GR emits the first-order diffracted beams DLr, DLg, and DLb at the emission angles βr, βg, and βb within the positive angle range, as shown in FIG. Although not shown, this diffraction grating emits first-order diffracted light in the same manner for light of other wavelengths.

  On the other hand, when the grating constant d of the diffraction grating is larger than ½ of the shortest wavelength of visible light and less than the shortest wavelength of visible light, the illumination light IL is irradiated from an oblique direction to the interface IF. As shown in FIG. 8, the diffraction grating GR emits the first-order diffracted beams DLr, DLg, and DLb at the emission angles βr, βg, and βb within the negative angle range, respectively. For example, considering the case where the angle α is 50 ° and the grating constant d is 330 nm, the diffraction grating GR diffracts light having a wavelength λ of 540 nm (green) in the white illumination light IL, and causes the first-order diffracted light DLg. Are injected at an injection angle βg of about −60 °.

  As is clear from this explanation, the relief structure DS emits diffracted light only in the negative angle range without emitting diffracted light in the positive angle range. Alternatively, the relief structure DS emits only diffracted light with low visibility within a positive angle range, and emits diffracted light with high visibility within a negative angle range. That is, unlike the normal diffraction grating, the relief structure DS emits diffracted light with high visibility only within a negative angle range.

  In general, when illuminating the surface of an article from a light source disposed above and observing the appearance of the article surface with reflected light from the article surface (hereinafter referred to as “reflection observation”), in particular, light reflectivity and light scattering When observing a light-absorbing article having a small ability, the article and the light source are aligned relative to the observer's eyes so that specularly reflected light can be seen. Therefore, when the configuration described with reference to FIG. 7 is adopted as the relief structure DS of the display body 1, the viewer visually recognizes the diffracted light with a relatively high probability even if the viewer does not know this. On the other hand, when the configuration described with reference to FIG. 8 is adopted as the relief structure DS of the display body 1, an observer who does not know it cannot perceive diffracted light in many cases. Therefore, it is difficult for the display body 1 to realize that the first interface 2 can emit diffracted light under the condition of reflection observation.

  Further, as described above, the convex part PR has a tapered shape. When such a structure is employed, if the average center distance AD is sufficiently short, the relief structure DS can be regarded as having a refractive index that continuously changes in the Z1 direction. Therefore, the reflectance of the regular reflection light of the relief structure DS is small no matter which angle is observed. The relief structure DS does not substantially emit diffracted light in front of the display body 1 (normal direction).

  Therefore, the portion of the display body 1 corresponding to the relief structure DS displays, for example, black or dark gray when reflected from the normal direction. Here, “black” means that the wavelength corresponding to the relief structure DS in the display body 1 is irradiated with light from the normal direction and the intensity of specular reflection light is measured, and the wavelength is within a range of 400 nm to 700 nm. Means that the reflectance is 10% or less with respect to all the light components, and “dark gray” means that the portion corresponding to the relief structure DS of the display body 1 is irradiated with light from the normal direction, and the regular reflection light When the intensity is measured, it means that the reflectance is about 25% or less for all light components whose wavelength is in the range of 400 nm to 700 nm which is the wavelength of visible light.

As described above, the relief structure DS displays black or dark gray when observed from the front. Therefore, the portion of the display body 1 corresponding to the first interface portion 2 looks like, for example, a black or dark gray print layer when observed from the front.
Since the relief structure DS displays black or dark gray when observed from the front of the display body 1, when the observation angle is in a negative angle range, the relief structure DS has a chromatic color derived from diffraction. indicate.

The average center distance AD of the protrusions PR is 500 nm or less, and is preferably shorter than the shortest wavelength of visible light (for example, 400 nm or less). More preferably, a structure having a function of emitting the first-order diffracted light and appearing black or dark gray is obtained by setting the wavelength to 1/2 or more of the shortest wavelength of visible light, that is, 200 nm to 400 nm. When the average center-to-center distance AD is set to less than 200 nm, a structure that looks black or dark gray can be obtained, but the function of emitting the first-order diffracted light cannot be obtained.
Generally, as the average center distance AD of the convex part PR decreases, the brightness and saturation decrease, enabling a black display, and the brightness increases slightly as the average center distance AD increases. However, the structure is perceived as dark gray.

  In addition, the higher the height of the convex part PR, the more black display is possible, and the luminance increases as the height becomes smaller, and it is perceived as dark gray. Typically, it is desirable that the height of the convex part PR is 1/2 or more of the average center distance AD. Specifically, when the average center-to-center distance AD is 500 nm, dark gray can be displayed by setting the height of the convex part PR to 250 nm or more, and further, 500 nm or more which is larger than the average center-to-center distance AD. By making the height of, black display becomes possible.

  If the height of the convex part PR is made much higher than the average center-to-center distance AD, sufficient black can be obtained, and more precise manufacturing technology is required, so the forgery prevention effect is further improved. Can be made. About the height of the convex part PR, different values may be taken for each individual convex part, and it may be formed with a uniform height. In this case, it is desirable that luminance unevenness due to slight fluctuations in blackness due to unevenness in the height of the convex portions hardly occur.

Next, the behavior of light transmitted through the first interface portion where the plurality of convex portions PR are formed will be described.
The first interface 2 has an action similar to that of an interference filter formed by the optical thin film 30 shown in FIG. 9, and can reinforce or weaken light of a specific wavelength by repeating reflection and interference. A part of the incident light IL incident on the optical thin film 30 at an angle θ is reflected by the surface of each layer and is reflected to the side where the light source LS is present, but is transmitted light and proceeds to the surface opposite to the light source LS. There is also light to do.

The wavefront of the light that passes through the optical thin film 30 is a superposition of the wavefront of the light that passes through the optical thin film 30 after being repeatedly reflected an even number of times. When there is no phase difference between the wavefronts, the maximum transmitted light is obtained, and the difference in optical distance at that time is an integral multiple of the wavelength, and the following equation (2) is established.
mλ = 2 × TO × cos θ (2)
Here, m is the order and TO is the optical distance. TO takes into account the refractive index of the medium through which light propagates in addition to the physical distance. When the film thickness of the optical thin film 30 is D and the refractive index is n, TO = nD is established.
At this time, interference canceling out at each wavefront occurs at other wavelengths, so that the light hardly transmits to the surface opposite to the light source LS. This means that the wavelength of light transmitted to the surface opposite to the light source can be controlled by controlling the optical distance of the thin film.

  By changing the average center-to-center distance AD of the projections PR provided on the first interface portion 2, the optical distance to the incident light of the light transmissive resin layer 112 and the metal thin film layer 12 can be changed. Like the optical thin film 30, the interface 2 can emit light having a specific wavelength with respect to incident light from a specific angle as transmitted light on a surface opposite to the light source. That is, by changing the average center distance AD of the projections PR provided on the first interface portion 2, the light of a specific wavelength such as red, green, and blue is emitted from the fixed point with respect to the incidence of the white light IL. It can be emitted as transmitted light.

Next, the visual effect by the display body 1 shown in FIG. 1 is demonstrated.
FIG. 10 is a diagram showing an example of observing the front surface of the display body 1 with reflected light from the display body 1, and FIG. 11 is another example of observing the front surface of the display body 1 with reflected light from the display body 1. FIG. 12 is a diagram illustrating an example of observing the front surface of the display body 1 with transmitted light from the display body 1.
As shown in FIG. 10, for example, light from a white light source LS such as the sun or a fluorescent lamp above the observer OB enters the display body 1, and the observer OB receives reflected light RE from the surface of the display body 1. Under observation conditions such as observing, the first interface portion 2 of the display body 1 emits almost no reflected light RE due to the antireflection / suppression effect by the plurality of convex portions PR formed therein, and is black or Observed in dark gray.

As shown in FIG. 11, when the display body 1 is viewed by reflection observation with the light emitted from the display body 1, the incident light IL is made incident on the display body 1 at an angle satisfying the condition of the expression (1). By observing the display body 1 from the angle at which the diffracted light is emitted, the diffracted light DL from the first interface portion 2 can be observed.
As shown in FIG. 12, when the display body 1 is observed in such a positional relationship that a white light source LS such as the sun or a fluorescent lamp is on the back side of the display body 1 with respect to the observer OB, the white light source LS is emitted. Incident light IL to the display body 1 enters from the back surface of the display body 1 and reaches the observer OB as light TR transmitted through the first interface 2. At this time, the wavelength of the light TR transmitted through the first interface portion 2 is determined according to the average center distance AD of the plurality of convex portions PR formed inside the first interface portion 2, so that the first interface The display body 1 can display unique hues such as blue, red, and green by the light TR transmitted through the portion 2.

  The plurality of convex portions PR constituting the first interface portion 2 have an average center distance AD of 200 nm to 500 nm and a height of 300 nm to 500 nm. When the first interface part 2 is constituted by such a convex part PR, as shown in FIG. 10, when the display body 1 is reflected and observed, it looks black or dark gray. As shown in FIG. 11, the first interface 2 emits diffracted light under specific conditions. Furthermore, as shown in FIG. 12, when the display body 1 is observed through transmission, a unique hue can be displayed by the transmitted light. Such a structure that realizes a characteristic perceptual effect that is completely different between reflection observation and transmission observation cannot be realized with other structures, and exhibits a high anti-counterfeit effect.

When the average center distance AD of the convex portions PR is larger than 500 nm, it becomes difficult to display sufficiently dark colors such as black or dark gray when the reflection is observed, and a unique hue color is displayed when the transmission is observed. Thus, only the effect of transmitting light having a wavelength distribution that hardly changes with the color of the light source can be obtained.
It is desirable to provide the display body 1 with a plurality of first interface portions 2 having different average center distances of the convex portions PR. By changing the average distance between the centers of the protrusions PR, it is possible to display colors of different hues for each first interface portion 2 when observing through transmission. Each first interface 2 is formed by a plurality of convex portions PR having an average center-to-center distance AD of 200 nm to 500 nm and a height of 300 nm to 500 nm. When the transmission is observed, different hue colors can be displayed according to the average center distance.

  FIG. 13 is a perspective view showing a display body according to the second embodiment of the present invention. The display body 1 shown in FIG. 13 has three first interface portions 3, 4, and 5, and these first interface portions 3, 4, and 5 have an average center-to-center distance that is different for each character “TOP”. It is formed from a plurality of convex portions arranged. When the observer OB observes the display body 1, different colors are displayed for each of the characters “T”, “O”, and “P”. By providing a plurality of first interface portions with different distances, it is possible to realize a higher anti-counterfeit effect and to enhance the design.

  FIG. 14 is a diagram illustrating an example where a plurality of first interface portions having different average center-to-center distances are alternately arranged adjacent to each other. As shown in FIG. 14, first interface portions 3, 4, 5 having different average center-to-center distances are alternately arranged adjacent to each other, and, for example, the letter “T” is formed by the first interface portions 3, 4, 5. By doing so, it is also possible to display so-called mixed colors. In this case, each of the first interface portions may be formed in a minute region included in a rectangle having a side of 3 μm or more and 300 μm or less, and regularly arranged adjacent to each other. When the letter “T” in which a plurality of minute first interface portions are arranged adjacently is observed with the naked eye, it is not possible to distinguish each of the first interface portions from the first interface portion adjacent thereto. It is possible or difficult. Therefore, when the character “T” is observed with the naked eye, each shape of the first interface portion can be prevented from being recognized by the observer. That is, it becomes difficult to recognize the outer shape of each of the first interface portions with the naked eye, and the mixed light can be displayed by the light of a plurality of wavelengths by mixing the transmitted light from the plurality of adjacent first interface portions. By using such a method, the number of colors that can be displayed increases, and the design is improved.

  As an arrangement example of the plurality of first interface portions, a method of arranging in a checkered pattern (check pattern shape) or a stripe shape (strip shape) in which two types of first interface portions having different average center-to-center distances are alternately arranged. Alternatively, there is a method in which three or more types of first interface portions are arranged in order so that they appear at the same rate and the same area within a predetermined region. Here, when one side of the first interface portion is 3 μm or less, it is difficult to form the convex portions with sufficiently high density and shape accuracy.

As a metal thin film layer, it is preferable that the layer thickness in a flat surface is the range of 30 nm or more and 100 nm or less. A metal such as aluminum, silver, or gold can be formed into a thin film with high accuracy by following the relief structure by a vapor deposition method such as a vacuum evaporation method or a sputtering method.
An example of the metal thin film layer 12 is shown in FIG. The metal thin film layer 12 shown in FIG. 15 has a flat surface FL formed with a layer thickness T1 by a vapor deposition method, and the side surface portion of the relief structure DS is formed with a layer thickness T2 that is relatively thinner than the layer thickness T1. Has been. If the height of the relief structure DS is high, the layer thickness T2 becomes thinner. Therefore, the first interface portion where the relief structure DS is provided is more likely to transmit light compared to the flat surface FL, a diffraction grating, a light scattering structure, and the like described later.

  An example of light reflection characteristics and transmission characteristics with respect to the metal thin film layer 12 is shown in FIG. As shown in FIG. 16, the reflected light and the transmitted light are in an inversely proportional relationship. By setting the layer thickness of the flat surface FL of the metal thin film layer 12 in the range of 30 nm or more and 100 nm or less, not only the reflected light component but also the transmitted light component can be obtained at the first interface portion that is thinner than the layer thickness. Thus, the perceptual effect as described above can be realized in both reflection observation and transmission observation.

Next, the second interface 20 shown in FIGS. 1, 2, and 10 to 13 will be described.
The second interface portion 20 is a region other than the first interface portion arranged in the display body 1. There may be a plurality of the second interface portions 20 or there may not be one. The second interface portion 20 is a region that differs in structure and optical properties from the first interface portion. The second interface region may have a different structure from the first interface region, or may be a flat surface on which no structure is formed.

An example of a structure that can be used for the second interface 20 is a diffraction grating GR as shown in FIG. This diffraction grating GR has a structure in which grating lines are arranged at intervals of about 1 to 2 μm, and a typical height is about 100 nm. In addition, the diffraction grating GR shown in FIG. 17 emits a rainbow-colored spectral color by diffraction, and displays an image whose color or pattern changes according to the observation conditions such as the position of the light source and the observation angle of the observer. Or a function of displaying a stereoscopic image. The pitch of the diffraction grating that can be employed in the second interface is typically larger than 500 nm, and it is preferable that the anti-reflection effect is not likely to occur due to the concave-convex structure of the diffraction grating.
The diffraction grating emits a rainbow-colored spectral color by diffraction in both reflection observation and transmission observation, so that no significant difference is observed when the display 1 is observed on the front and back.

Moreover, as a structure employable for the 2nd interface part 20, the light-scattering structure 21 as shown, for example in FIG. 18 is mentioned. The light scattering structure 21 is typically a structure in which a plurality of irregular shapes having different sizes, shapes, and heights are irregularly arranged. The light incident on the light scattering structure 21 is irregularly reflected in all directions, and appears white or cloudy when reflected. Typically, the light scattering structure 21 is typically a structure having a width of 3 μm or more and a height of 1 μm or more, which is larger than the concavo-convex structure formed at the diffraction grating or the first interface portion. Moreover, the size, arrangement interval, and shape are not uniform. Therefore, the effect of scattering light is obtained. When a concavo-convex structure having a certain degree of directivity is adopted as the light scattering structure 21, it is possible to realize a light scattering property having directivity that emits scattered light strongly only in a desired direction.
The light scattering structure 21 also appears white or cloudy regardless of reflection observation or transmission observation, so that no significant difference is observed when the display 1 is observed on the front and back.

Further, the second interface portion 20 may be a flat surface on which no concavo-convex structure is formed.
Adopting the second interface portion 20 as a part of the display body 1 and combining the second interface portion 20 with the first interface portion 2 or 3, 4, 4, the design of the image expressed by the display body 1 Further improvement can be achieved, and the effect of preventing forgery can be further improved.
The second interface portion 20 may be formed with a structure other than the above-described structure that exhibits optical characteristics different from those of the first interface portion 2 or the first interface portions 3, 4, and 5.

Next, the usage method of the display body 1 is demonstrated.
The display body 1 described above can be affixed as a label to a light-transmitting article via a light-transmitting adhesive, adhesive, or the like for the purpose of preventing counterfeiting, for example. Examples of the light-transmitting article include various admission tickets and banknotes using a plastic substrate, and a package sheet and case. As described above, the display body 1 is difficult to counterfeit or imitate itself. Therefore, when this label is supported on an article, it is difficult to counterfeit or imitate the genuine article with label.

19 is a plan view showing an example of a labeled article, and FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. 19 and 20 illustrate a light-transmissive concert admission ticket 100 as an example of a labeled article. This admission ticket 100 contains the base material 50 which has a light transmittance. The base material 50 is made of plastic such as PET or PC. A printed layer 40 is formed on one main surface of the substrate 50. The display body 1 mentioned above is being fixed to the surface in which the printing layer 40 of the base material 50 was formed through the adhesion layer which has a light transmittance, for example. For example, the display body 1 is prepared as an adhesive sticker or a transfer foil, and is fixed to the substrate 50 by sticking the display body 1 to the printing layer 40. Printing is not provided in a place where the display body 1 is fixed so as not to block light transmission.
The admission ticket 100 includes a display body 1. Therefore, forgery or imitation of this admission ticket 100 is difficult.

  In FIG. 19 and FIG. 20, an admission ticket is illustrated as an article including the display body 1, but the article including the display body 1 is not limited to this. For example, the article including the display body 1 may be cards such as an IC (integrated circuit) card, a wireless card, and an ID (identification) card. Alternatively, the article including the display body 1 may be a plastic banknote or a stamp. Alternatively, the article including the display body 1 may be a tag to be attached to an article to be confirmed as an authentic product. Alternatively, the article including the display body 1 may be a package body that contains an article to be confirmed to be genuine or a part thereof.

Moreover, in the admission ticket 100 shown in FIG.19 and FIG.20, although the display body 1 is affixed on the base material 50 via the printing layer 40, the display body 1 is made to support a base material by another method. Can do. For example, the display body 1 may be embedded in the base material, or the display body 1 may be fixed to the back surface of the base material, that is, the surface opposite to the display surface.
The display body 1 may be used for purposes other than forgery prevention. For example, the display body 1 can be used as a toy, a learning material, or a decoration.

  DESCRIPTION OF SYMBOLS 1 ... Display body, 2 ... 1st interface part, 3 ... 1st interface part, 4 ... 1st interface part, 5 ... 1st interface part, 11 ... Light transmission layer, 12 ... Metal thin film layer, 20 ... 2nd interface Part 21 ... light scattering structure 30 ... optical thin film 40 ... printing layer 50 ... plastic base material 100 ... admission ticket 111 ... light transmissive base material 112 ... light transmissive resin layer AD ... average center D: optical thin film thickness, DL: diffracted light, DLb: first order diffracted light, DLg: first order diffracted light, DLr: first order diffracted light, DS: relief structure, FL: flat surface, GR: diffraction grating, IF ... interface, IL ... incident light, LS ... white illumination light, NL ... normal line, OB ... observer, PR ... convex part, TR ... transmitted light, RE ... reflected light, RL ... specular reflected light or 0th order diffracted light, T1 ... layer thickness of flat part, T2 ... layer thickness of side face of convex part, α ... incident angle, βb ... injection angle, βg ... injection angle, βr ... injection angle, θ …Angle of incidence

Claims (6)

A display body formed from a laminate formed by laminating a light transmission layer on a metal thin film layer having both light reflectivity and light transmittance,
It consists of a plurality of convex portions protruding from the metal thin film layer toward the light transmissive layer or a plurality of concave portions recessed from the light transmissive layer toward the metal thin film layer, and the convex portion or the concave portion is 200 nm or more and 500 nm or less. A plurality of first interface portions arranged in a grid pattern with an average center-to-center distance, and a relief structure forming layer is formed at the interface portion between the metal thin film layer and the light transmission layer by the first interface portion. And
The layer thickness on the flat surface of the metal thin film layer is in the range of 30 nm or more and 100 nm or less, and is thicker than the layer thickness of the metal thin film layer in the side surface portion of the convex portion or the concave portion,
The display unit according to claim 1, wherein the first interface emits light having a different wavelength according to the average center-to-center distance as incident light on the surface opposite to the light source.   The display body according to claim 1, wherein an average center-to-center distance of the convex portion or the concave portion is different in each of the plurality of first interface portions.   The display body according to claim 2, wherein an image of a pattern, a character, a symbol, or the like is displayed by the plurality of first interface portions having different average center distances between the convex portions or the concave portions.   The average distance between the centers of the protrusions or the recesses is such that the principal wavelength of light transmitted through each of the plurality of first interface portions is mixed in a region included in a rectangle composed of four sides of 3 μm or more and 300 μm or less. The display body according to any one of claims 1 to 3, wherein three or more kinds of first interface portions different from each other in a range of 200 nm to 500 nm are regularly arranged adjacent to each other.   2. The display body according to claim 1, wherein angles at which the convex portions or the concave portions are arranged are different from each other in the plurality of first interface portions configured by rectangles having four sides of 3 μm or more and 300 μm or less. .   The label according to claim 1, wherein the display body according to claim 1 is supported by an article made of a light-transmitting base material via a light-transmitting adhesive layer. Goods.

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