WO2016047122A1 - Structural color display - Google Patents

Abstract

Provided are: a structural color display capable of preventing an image (especially the hue thereof) displayed using structural colors from changing depending on the observation angle of observers; and an image display object using same. This image display device (10) upon which images are displayed using structural colors comprises at least: an image display sheet (1) having a structural color expression area (R1) being an area in which structural colors are expressed; and an incident/reflected light limiting unit (2) arranged on the image display side of the structural color expression area (R1) and selectively transmitting incident light and reflected light, said incident light being incident, at a pre-set angle, to a surface (S1) in the structural color expression area (R1) positioned on the image display side and said reflected light being incident light that has been reflected by part of the structural color expression area (R1).

Description

Structural color display

The present invention relates to a structural color display and an image display using the same.

In the technical field of image display devices, devices that display images using structural colors are already known. Examples of this type of image display device include those described in Patent Document 1 and Patent Document 2.

JP 2007-11112 A JP 2009-139800 A

Many structural color displays that display an image using a structural color display a desired image using visible light having a wavelength determined by Bragg's law. For this reason, the structural color display according to the prior art has a problem that the displayed image (particularly its color) changes depending on the observation angle of the observer. This point will be briefly described with reference to FIG. Hereinafter, “structural color display” is also simply referred to as “image display device”.

FIG. 12 is a schematic diagram for explaining a problem in the image display device according to the prior art. FIGS. 12A and 12B are diagrams schematically illustrating a case where images displayed on the image display device 20 according to the related art are observed at different angles. As shown in FIG. 12A and FIG. 12B, the distance of light traveling in the image display sheet 1 (that is, the optical path length) varies depending on the observation angle of the observer. For this reason, the wavelength of the light which interferes changes and the color (namely, wavelength of reflected light) of the image displayed with the image display apparatus 20 changes. In FIG. 12, “3a” indicates incident light, and “3b” indicates reflected light (structural color).

The present invention has been made in view of such circumstances, and a structural color capable of preventing an image (particularly the color) displayed using the structural color from changing depending on the viewing angle of the observer. An object is to provide a display and an image display using the display.

In order to solve the above problems, an aspect of the present invention is an image display device that displays an image with a structural color, the image display sheet having a structural color expression region that is a region that expresses the structural color, Incident light that is placed on the image display side of the structural color expression region and is incident at a predetermined angle with respect to the surface of the structural color expression region located on the image display side, and the structure of the incident light The structural color display includes at least an incident / reflected light limiting unit that selectively transmits reflected light reflected by a part of the color expression region.

The structural color display according to one aspect of the present invention can prevent an image displayed using the structural color from changing depending on the observation angle of the observer. Note that the observation angle referred to in one embodiment of the present invention is an observation angle of a person who views the display device, and is a concept different from “a viewing angle in a liquid crystal display”.

1 is a conceptual cross-sectional view illustrating a configuration of an image display device according to a first embodiment of the present invention. It is a schematic diagram for demonstrating the expression mechanism of the structural color in the image display apparatus which concerns on 1st Embodiment of this invention. It is a conceptual sectional view showing the composition of the image display device concerning a 2nd embodiment of the present invention. It is a schematic diagram for demonstrating the sheet | seat thickness change in the image display apparatus which concerns on 2nd Embodiment of this invention. It is a conceptual sectional view showing the composition of the image display device concerning a 3rd embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning a 4th embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning a 5th embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning a 6th embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning a 7th embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning an 8th embodiment of the present invention. It is a conceptual sectional view showing the composition of the image display device concerning a 9th embodiment of the present invention. It is a schematic diagram for demonstrating the subject in the image display apparatus which concerns on a prior art. It is the schematic which shows the principle of structural color expression of a colloid crystal. It is the schematic which shows the principle of structural color expression of a multilayer structure. It is a figure which shows the outline | summary of a structural color measuring apparatus. It is a figure which shows the spectral distribution of the light source used for structural color measurement. It is a figure which shows the measurement position of the structural color (chromaticity and brightness | luminance) in Experimental example 1 and 2. FIG. In Experimental example 1, it is an xy chromaticity diagram which shows the locus | trajectory of the chromaticity change accompanying the change of an observation angle. It is a figure which shows the observation angle dependence of the brightness | luminance in Experimental example 1. FIG. In Experimental example 2, it is an xy chromaticity diagram which shows the locus | trajectory of the chromaticity change accompanying the change of an observation angle. It is a figure which shows the observation angle dependence of the brightness | luminance in Experimental example 2. FIG. It is a figure which shows the measurement position of the structural color (chromaticity and brightness | luminance) in Experimental example 4. In Experimental example 4, it is xy chromaticity diagram which shows the locus | trajectory of chromaticity change accompanying the change of an observation angle. It is a figure which shows the observation angle dependence of the brightness | luminance in Experimental example 4. FIG. It is a figure which shows the measurement position of the structural color (chromaticity and brightness | luminance) in Experimental example 5. In Experimental example 5, it is an xy chromaticity diagram which shows the locus | trajectory of chromaticity change accompanying the change of an observation angle. It is a figure which shows the observation angle dependence of the brightness | luminance in Experimental example 5. FIG.

Embodiments according to the present invention will be described below with reference to the drawings. In each drawing, parts having the same configuration and the same function are denoted by the same reference numerals.
[First Embodiment]
Hereinafter, the configuration of the image display apparatus 10 according to the first embodiment will be described. FIG. 1 is a conceptual cross-sectional view showing a configuration of an image display device 10 according to the first embodiment of the present invention. As shown in FIG. 1, an image display device 10 is an image display device that displays an image with a structural color, and includes an image display sheet 1 having a structural color expression region R1 that is a region that exhibits a structural color, and a structure. Incident light that is installed on the image display side of the color expression region R1 and is incident on the surface S1 on the image display side at a preset angle, and reflected light that is reflected by a part of the structural color expression region R1 of the incident light And the incident / reflected light limiting unit 2 that selectively transmits the light. Hereinafter, each of the members will be described.

(Image display sheet 1)
The image display sheet 1 is a sheet-like member that can express a structural color. The image display sheet 1 includes, for example, a thin film or plate integrally formed using a resin having a preset refractive index, or a gas having a preset refractive index between two sheets disposed opposite to each other. A laminate formed by filling one of a liquid and a solid can be used. Here, examples of the substance filled between the two sheets include a voltage-responsive polymer gel whose volume changes according to the applied voltage.
In addition, the image display sheet 1 should just be able to express a structural color, for example, the material and shape are not ask | required. Moreover, the size does not ask | require. As this image display sheet 1, for example, a structure in which a resin film having a lamellar structure, a chargeable organic polymer or inorganic spherical particles are migrated and regularly aligned in a vertical and horizontal direction on a predetermined support surface Using a metal structure having a nanostructure on the surface and a substrate having protrusions and recesses formed on the surface, the protrusions and recesses are imprinted on a plurality of resin plates by a nanoimprint technique, and the replication is performed. A substrate with a plurality of resin plates bonded together, an expansion / contraction body such as a stimulus-responsive polymer gel that changes in volume according to the electric field, a periodic structure disposed in the expansion / contraction body, and a structural color A sphere and a matrix having a display layer that expresses and a reflective interface that reflects light transmitted through the display layer, a laminate in which high-refractive index layers and low-refractive index layers are alternately stacked, and a wavelength of visible light 1 / An integral multiple of 2 wavelengths It can be exemplified microstructure or the like having a regular microstructure which is periodic interval.

The image display sheet 1 has a structural color expression region R1 that is a region that expresses a structural color (a region for displaying an image). The thickness of the image display sheet 1 in the structural color expression region R1 is substantially uniform over the entire structural color expression region R1.
The structural color expression region R1 may be any size, shape, or number.
Hereinafter, the structural color expression region R1 will be described in more detail.
The structural color expression region R1 is not particularly limited as long as it is formed of a structural color material having a function of expressing a structural color based on the principle of light interference. At that time, the structure of the structural color material is as follows: (1) colloidal crystal structure in which colloidal particles are dispersed in a medium, (2) inverse opal structure, (3) multilayer structure, (4) lamellar structure, (5) Any of a thin film structure may be sufficient. The colloidal crystal structure of (1) includes a polymer gel formed by dissolving and polymerizing a monomer and a crosslinking agent in a dispersion medium of colloidal particles. A hydrophilic polymer gel (hydrogel) can be suitably used as the polymer gel. In addition, the lamellar structure (4) includes a self-aggregating lamellar structure formed by self-aggregation of a (polymer) surfactant, in addition to a lamellar structure formed by a microphase-separated structure of a block polymer.
Further, the structural color material may be a stimulus-responsive structural color material that responds to the external stimulus already described.

In adopting the structural color material, the structural color material is selected in consideration of formula (1) or formula (3) corresponding to the structure of the structural color material, which will be described later.
Stimulus-responsive structural color materials include, for example, electric fields, deformation (strain / stress), heat, electromagnetic waves (including visible light, ultraviolet rays, and X-rays), moisture / moisture, magnetism, pH change, solvent contact, and other stimuli A structural color material composed of a stimulus-responsive material that responds and changes its volume or Bragg period can be suitably used.

(Incoming / reflecting light limiting unit 2)
On the surface S1 on the image display side of the structural color expression region R1, the incident / reflected light limiting unit 2 is disposed. The incident / reflected light limiting unit 2 includes incident / reflected light transmission regions R2 (R2a to R2f), and the incident / reflected light transmission region R2 includes incident light incident at a preset angle with respect to the surface S1, and This refers to a region that selectively transmits reflected light reflected by a part of the structural color expression region R1 (for example, the surface S2) of the incident light. FIG. 1 shows incident light incident at an angle in the range of 80 ° to 90 ° with respect to the surface S1 (that is, 0 ° to 10 ° with respect to the normal of the surface S1), and An incident / reflected light limiting unit 2 having an incident / reflected light transmission region R2 (R2a to R2f) that selectively transmits reflected light reflected at an angle is illustrated.

In the incident / reflected light limiting unit 2, for example, urexite arranged so as to transmit incident light incident along the thickness direction of the image display sheet 1 and optical fibers extending along the same direction are fixed in a bundle. It is possible to use one provided with at least one of the bundled optical fibers. In the case where the one provided with at least one of the urexite and the bundled optical fiber is used as the incident / reflected light limiting unit 2, for example, the light enters the surface S1 at an angle in the range of 80 ° to 90 °. It becomes easy to selectively transmit incident light and reflected light reflected at an angle within the range. Here, “Urexite” is an ore generally called a television stone, and is an aggregate in which transparent fibrous crystals are arranged completely in parallel.
The incident / reflected light limiting unit 2 only needs to be able to selectively transmit incident light and reflected light, and may be of any material or shape. Moreover, the size does not ask | require. Similarly, the incident / reflected light transmission region R2 (R2a to R2f) may have any size, shape, or number.
Further, the “bundle optical fiber” is obtained by cutting a plurality of optical fibers in which the axes are bundled and welded in a direction perpendicular to the axis into a plate shape. When this bundled optical fiber is placed on a paper surface, characters on the paper surface appear to float.
Hereinafter, the incident / reflected light limiting portion 2 made of urexite is referred to as a “Urexite plate”, and the incident / reflected light limiting portion 2 formed of a bundle of optical fibers is referred to as a “bunched optical fiber plate”.

Also, as the bundle optical fiber, a tapered bundle optical fiber can be used. If this taper-type bundle optical fiber is used, the image in which the structural color material appears can be enlarged.

<Structure mechanism of structural color>
First, “structural colors” will be briefly described.
The structural color is a color due to light interference caused by the fine periodic structure of the object. Beautiful colors such as iridescent insects and gem opals are also due to structural colors. In recent years, a material exhibiting a structural color (hereinafter referred to as “structural color material”) in which a sub-microscale fine periodic structure is formed has been developed. There are various types of the above fine periodic structures, but typical structures include (1) colloidal crystal structure in which colloidal particles are dispersed in a medium (opal structure), (2) inverse opal structure, and (3) multilayer structure. (4) Lamella structure is known. Any of the structures (1) to (4) is characterized by having a periodic structure in which a high refractive index phase and a low refractive index phase are arranged at a predetermined period. In addition, (5) thin film structures represented by soap bubbles also emit structural colors due to light interference caused by multiple reflection.
Recently, a structural color material that can variably control the period of the periodic structure by applying an external stimulus has been developed. For example, electric field, deformation (strain / stress), heat, moisture (moisture), magnetism, pH change, solvent contact, etc. are known as stimuli (hereinafter, structural colors that change the hue of the structural color by applying stimuli) The material may be referred to as “stimulus responsive structural color material”). In any case, these stimuli change the (Bragg) period or refractive index of the periodic structure, and as a result, use the property that the structural color to be visually recognized changes.

Next, with reference to FIG. 2, a structure color expression mechanism of the image display device 10 will be briefly described.
FIG. 2 is a schematic diagram for explaining the mechanism of expression of structural colors in the image display device 10. FIG. 2 shows the image display sheet 1 having the structural color expression region R1 and the incident / reflected light limiting unit 2 arranged on the structural color expression region R1. In FIG. 2, incident light 3a incident at an angle within a range of 80 ° to 90 ° with respect to the surface S1 (that is, an incident angle is 0 ° to 10 °) and reflected at an angle within the range. A single incident / reflected light transmission region R2 (R2a) that selectively transmits the reflected light 3b is illustrated. That is, FIG. 2 shows a part of the image display device 10 in an enlarged manner.

First, light (for example, sunlight) is irradiated toward the image display sheet 1 shown in FIG. At this time, the angle of light incident on the structural color expression region R1 is limited to an angle in the range of 80 ° to 90 ° with respect to the surface S1 by the incident / reflected light transmission region R2. Here, the “angle within the range of 80 ° or more and 90 ° or less” is an angle that is set in advance in the first embodiment and can be arbitrarily selected. A part of the incident light 3a that reaches the structural color expression region R1 is reflected by the surface S1. Further, another part of the incident light 3a is reflected by the surface S2, for example. In this way, the reflected light 3b reflected by different surfaces (locations) interferes with each other, so that a structural color appears. The expressed structural color transmits through the incident / reflected light transmission region R2 and is observed (viewed) by the observer.

As described above, the angle of the light (incident light 3a) incident on the structural color expression region R1 and the angle of the light (reflected light 3b) reflected on the structural color expression region R1 are set as the incident / reflected light limiting unit 2. It can be limited (fixed) by. For this reason, even when the observation angle of the observer changes, the optical path length itself in the image display sheet 1 does not change, so the wavelength of the structural color to be expressed does not change. Therefore, according to the image display device 10 according to the first embodiment, it is possible to prevent the image displayed using the structural color from changing depending on the observation angle of the observer.

<Dependence of structural color on observation angle in case of colloidal crystal or inverted opal structure>
Next, the observation angle dependence of the structural color in the case of a colloidal crystal or an inverse opal structure will be described with reference to FIG.
The observation angle dependence of the structural color is quantitatively shown by the following formulas (1) and (3) based on the structural color expression structure. The relational expression between Expression (1) and Expression (3) is applicable even when the positional relationship between the observer and the structural color display is the same and the position of the light source is changed.

λ _peak = 2d _C [n _eff ² −sin ² θ] ^1/2 (1)
Here, λ _peak : wavelength at which the reflectance becomes maximum θ: observation angle d _C : distance between crystal planes n _eff : effective refractive index.

In the above, n _eff is calculated by the following formula (2).
n _eff = (1−φ) n _M + φn _D (2)
Where n _{M is} the refractive index of the matrix (dispersion medium, continuous phase), n _{D is} the refractive index of the colloidal particles (dispersed phase), and φ is the volume fraction of the colloidal particles in the colloidal crystal.

<Depending on viewing angle of structural color in case of multilayer structure or lamellar structure>
Finally, the observation angle dependence of the structural color in the case of a multilayer structure or a lamella structure will be described with reference to FIG.

λ _peak = 2 [d ₁ (n ₁ ² −sin ² θ) ^1/2 + d ₂ (n ₂ ² −sin ² θ) ^1/2 ] (3)
Here, d ₁ : thickness of the first phase d ₂ : thickness of the second phase n ₁ : refractive index of the first phase n ₂ : refractive index of the second phase.
In Expressions (1) and (3), λ _peak is a wavelength at which the reflectance is maximum, and a hue based on this wavelength is observed (observed, visually confirmed). In any of the above formulas (1) and (3), the structural color to be visually recognized depends on the observation angle (θ). This situation also applies to the stimuli-responsive structural color material.

<How to use>
In the image display device 10, the regions where the incident / reflected light transmission region R2 and the structural color expression region R1 overlap each function as a pixel. For this reason, in the image display apparatus 10, it arrange | positions so that the image which preset each pixel may be displayed. The image display device 10 is installed outdoors, for example. Thereby, the sun can be used as the light source. By doing so, it is possible to display an image that does not require power for displaying an image and whose color or the like does not change depending on the observation angle of the observer.
In addition, what is necessary is just to change the thickness of the image display sheet 1 in the preset area | region, when displaying an image using a some structural color. By doing so, the optical path length in the image display sheet 1 changes, so that the color of the structural color can be changed. Thus, an image can be displayed using a plurality of structural colors.

[Second Embodiment]
Hereinafter, the configuration of the image display apparatus 11 according to the second embodiment will be described. FIG. 3 is a conceptual cross-sectional view showing the configuration of the image display device 11 according to the second embodiment of the present invention. As shown in FIG. 3, the structure of the image display device 11 is substantially the same as the structure of the image display device 10 according to the first embodiment described above, but the thickness d1 of the image display sheet 1 in the structural color expression region R1 is set as follows. It differs from the image display apparatus 10 in that the sheet thickness adjusting unit 4 to be adjusted is provided. Therefore, in the second embodiment, the sheet thickness adjusting unit 4 will be mainly described, and description of other components will be omitted.

(Sheet thickness adjusting unit 4)
The sheet thickness adjusting unit 4 is disposed at a position facing the incident / reflected light limiting unit 2 with the structural color expression region R1 interposed therebetween. As the sheet thickness adjusting unit 4, for example, one including an electrode (not shown) that contacts the image display sheet 1 can be used.
In addition, the sheet thickness adjustment part 4 should just be what can adjust the thickness d1 of the image display sheet 1 in the structural color expression area | region R1, for example, the means is not ask | required. Moreover, the size does not ask | require.
For example, the sheet thickness adjusting unit 4 may apply a stimulus to the stimulus-responsive structural color material. Examples of the stimulus applied by the sheet thickness adjusting unit 4 include an electric field, deformation (strain / stress), heat, light, and a magnetic field. The sheet thickness adjusting unit 4 can adjust the thickness d1 of the image display sheet 1 in the structural color expression region R1 by the stimulation.

<Color change mechanism of structural color>
Hereinafter, means (mechanism) for changing the color of the structural color using the sheet thickness adjusting unit 4 including the electrode will be described with reference to FIG. FIG. 4 is a schematic diagram for explaining a change in sheet thickness in the image display apparatus 11 according to the second embodiment. 4A shows the state before changing the thickness of the image display sheet 1 (sheet thickness d1), and FIG. 4B shows the state after changing the sheet thickness (sheet thickness d2). ing. Moreover, the image display sheet 1 shown to Fig.4 (a) and FIG.4 (b) is a sheet | seat containing the voltage-responsive polymer gel from which a volume changes according to the applied voltage. In addition, as an electrode which comprises the sheet thickness adjustment part 4 for electric field provision, the ITO (Indium Tin Oxide) electrode which does not interfere with visual recognition of a structural color can be used.

The electrode included in the sheet thickness adjusting unit 4 is in contact with the image display sheet 1, and when a voltage is applied to the electrode, the volume of the voltage-responsive polymer gel in the structural color expression region R1 responds to the applied voltage. Decrease or increase. Thus, the thickness of the image display sheet 1 in the structural color expression region R1 is adjusted by reducing or increasing the volume of the voltage-responsive polymer gel. FIG. 4B schematically shows how the volume of the voltage-responsive polymer gel increases in response to the applied voltage and the sheet thickness increases. Note that when the applied voltage is released, the volume of the voltage-responsive polymer gel returns to the state before voltage application, and thus the sheet thickness returns to the state shown in FIG.
When the thickness of the image display sheet 1 is changed as described above, the optical path length in the image display sheet 1 changes. Thus, the color of the structural color can be changed by changing the wavelength of the interfering light.

[Third Embodiment]
Hereinafter, the configuration of the image display device 12 according to the third embodiment will be described. FIG. 5 is a conceptual cross-sectional view showing the configuration of the image display device 12 according to the third embodiment of the present invention. As shown in FIG. 5, the structure of the image display device 12 is substantially the same as the structure of the image display device 10 according to the first embodiment described above, but the image display sheet 1 has a laminated structure. Different from the display device 10. Therefore, in the third embodiment, the image display sheet 1 having this laminated structure will be mainly described, and description of other components will be omitted.

(Image display sheet 1)
The image display sheet 1 provided in the image display device 12 is a multilayer structure in which structural color expression layers 1 a to 1 c that express a structural color are stacked along the thickness direction of the image display sheet 1. The thicknesses of the structural color developing layers 1a to 1c in the structural color developing region R1 are the same. In this way, by making the image display sheet 1 a multilayer structure, incident light can be reflected at the interfaces of the structural color developing layers 1a to 1c. When light is reflected from a plurality of surfaces, the wavelength range in which interference can occur is narrowed, so that the monochromaticity of the structural color that is expressed can be enhanced.
The thickness of each of the structural color developing layers 1a to 1c may be an integral multiple of the thickness of the reference layer when any one of the structural color developing layers 1a to 1c is used as the reference layer. Even in this case, the monochromaticity of the developed structural color can be enhanced. In the third embodiment, the above-described reference layer is the structural color expression layer 1a, and the thickness of each of the structural color expression layers 1b and 1c is set to be one time the thickness of the structural color expression layer 1a.
The structural color developing layers 1a to 1c are all made of the same material. By doing so, it is possible to reduce an increase in the manufacturing cost of the image display device 12.
The material and shape of each layer of the structural color expression layers 1a to 1c are not limited. Moreover, the size does not ask | require.

[Fourth Embodiment]
Hereinafter, the configuration of the image display device 13 according to the fourth embodiment will be described. FIG. 6 is a conceptual cross-sectional view showing the configuration of the image display device 13 according to the fourth embodiment of the present invention. As shown in FIG. 6, the structure of the image display device 13 is substantially the same as the structure of the image display device 11 according to the second embodiment described above, but between the image display sheet 1 and the incident / reflected light limiting unit 2. The image display device 11 is different from the image display device 11 in that a pixel partition frame (hereinafter, also simply referred to as “frame”) 5 for partitioning a pixel region is disposed. The image display device 11 is also different in that it includes a plurality of sheet thickness adjustment units 4 (4a to 4f). Therefore, in the fourth embodiment, the frame 5 and the sheet thickness adjusting units 4a to 4f will be mainly described, and the description of the other constituent members will be omitted. The number of structural color expression regions R1 (R1a to R1f) is not limited.

(Frame 5)
The frame 5 shown in FIG. 6 is a sheet-like member that is disposed between the image display sheet 1 and the incident / reflected light limiting unit 2 and absorbs visible light. The frame 5 includes an opening that exposes each of the structural color expression regions R1a to R1f to partition the pixel region.
Note that the frame 5 only needs to have an opening that divides the pixel region, and may be of any material or shape. Moreover, the size does not ask | require. For example, the frame 5 may be formed of an insulating film having electrical insulating properties, or may be formed of a material having elasticity (such as a buffer material). Further, the frame 5 is arranged as necessary, and is not an essential member in the present invention. Further, the shape, size, and number of the openings provided in the frame 5 are not limited. Further, the color of the frame 5 is, for example, black in order to clearly partition the pixel region.

(Sheet thickness adjusters 4a to 4f)
As shown in FIG. 4, the image display device 11 according to the second embodiment described above adjusts the sheet thickness of the structural color expression region R <b> 1 with one sheet thickness adjustment unit 4. On the other hand, in the image display device 13 according to the fourth embodiment, the sheet thicknesses of the plurality of structural color expression regions R1a to R1f are adjusted by the plurality of sheet thickness adjustment units 4a to 4f. More specifically, the sheet thickness adjusting units 4a to 4f provided in the image display device 13 are arranged so as to overlap the structural color expression regions R1a to R1f. In this way, the sheet thickness can be adjusted for each pixel. For example, as shown in FIG. 6, the red structural color R, the green structural color G, and the blue structural color B are displayed for each pixel. Can do. For this reason, an image with high resolution can be displayed. Further, with the above-described configuration, the red structural color R, the green structural color G, the blue structural color B, or the intermediate color can be freely displayed by one pixel.
The sheet thickness adjusting unit 4 provided in the image display device 11 and the sheet thickness adjusting units 4a to 4f provided in the image display device 13 have the same functions, although they are different in installation position and size.

[Fifth Embodiment]
Hereinafter, the configuration of the image display device 14 according to the fifth embodiment will be described. FIG. 7 is a conceptual cross-sectional view showing the configuration of the image display device 14 according to the fifth embodiment of the present invention. As shown in FIG. 7, the structure of the image display device 14 is the same as that of the image display device 13 according to the fourth embodiment described above except that the frame 5 is arranged so as to be embedded in the image display sheet 1. The same. Therefore, details of the structure of the image display device 14 are omitted here. In the image display device 14, a plano-convex lens 6 and microlens arrays 7 and 8 to be described later can be disposed on the incident / reflected light limiting unit 2.

[Sixth Embodiment]
The configuration of the image display device 15 according to the sixth embodiment will be described below. FIG. 8 is a conceptual cross-sectional view showing the configuration of the image display device 15 according to the sixth embodiment of the present invention. As shown in FIG. 8, the structure of the image display device 15 is substantially the same as the structure of the image display device 13 according to the fourth embodiment described above, but for widening the viewing angle on the incident / reflected light limiting unit 2. It differs from the image display device 13 in that it includes a plano-convex lens 6. Therefore, in the sixth embodiment, the plano-convex lens 6 will be mainly described, and description of other components will be omitted.

(Plano-convex lens 6)
The plano-convex lens 6 is a lens for widening the aperture angle of incident light and diffusing reflected light to widen the viewing angle. The plano-convex lens 6 is a lens having a plane and a convex surface located on the back side of the plane, and is arranged so as to cover the image display side of the incident / reflected light limiting unit 2. Further, in the state where the plano-convex lens 6 is disposed, the plane faces the incident / reflected light limiting unit 2 side. By doing so, the observer can observe the displayed image at a wider angle.
The plano-convex lens 6 may be any material and shape of the plano-convex lens 6 as long as the aperture angle of incident light is widened and the reflected light is diffused to widen the viewing angle. Moreover, the size does not ask | require.

[Seventh Embodiment]
The configuration of the image display device 16 according to the seventh embodiment will be described below. FIG. 9 is a conceptual cross-sectional view showing the configuration of the image display device 16 according to the seventh embodiment of the present invention. As shown in FIG. 9, the structure of the image display device 16 is substantially the same as the structure of the image display device 15 according to the sixth embodiment described above, but for widening the viewing angle on the incident / reflected light limiting unit 2. It differs from the image display device 15 in that the microlens array 7 is provided. Therefore, in the seventh embodiment, the microlens array 7 will be mainly described, and description of other components will be omitted.

(Microlens array 7)
Similar to the plano-convex lens 6 described above, the microlens array 7 is for widening the aperture angle of incident light and diffusing reflected light to widen the viewing angle. The microlens array 7 is composed of a plurality of microlenses 7a to 7h, and the microlenses 7a to 7h are planoconvex lenses having a plane and a convex surface located on the back side of the plane. The microlens array 7 is disposed so as to cover the image display side of the incident / reflected light limiting unit 2, and in the state where the microlens array 7 is disposed, the planes of the microlenses 7 a to 7 h are configured to limit the incident / reflected light. It faces the part 2 side. By doing so, the observer can observe the image at a wider angle.
Note that the microlens array 7 only needs to widen the aperture angle of incident light and diffuse the reflected light to widen the viewing angle. For example, the material and shape of the microlenses 7a to 7h are not limited. Moreover, the size and number are not ask | required. That is, the size of the microlenses 7a to 7h does not need to match the size of the pixel region (that is, the size of the opening of the frame 5 and the structural color expression regions R1a to R1f).

[Eighth Embodiment]
Hereinafter, the configuration of the image display device 17 according to the eighth embodiment will be described. FIG. 10 is a conceptual cross-sectional view showing the configuration of the image display device 17 according to the eighth embodiment of the present invention. As shown in FIG. 10, the structure of the image display device 17 is substantially the same as the structure of the image display device 16 according to the seventh embodiment described above, but for widening the viewing angle on the incident / reflected light limiting unit 2. It differs from the image display device 16 in that the microlens array 8 is provided. Therefore, in the eighth embodiment, the microlens array 8 will be mainly described, and description of other components will be omitted.

(Microlens array 8)
Similar to the microlens array 7 described in the seventh embodiment, the microlens array 8 is for widening the viewing angle. The microlens array 8 includes a plurality of microlenses 8a to 8f, and the microlenses 8a to 8f are planoconvex lenses each having a flat surface and a convex surface located on the back side of the flat surface. The microlens array 8 is disposed so as to cover the image display side of the incident / reflected light limiting unit 2, and in the state where the microlens array 8 is disposed, the planes of the microlenses 8 a to 8 f are limited to the incident / reflected light. It faces the part 2 side. Further, the diameters of the microlenses 8a to 8f coincide with the size of the pixel region (that is, the size of the opening of the frame 5 and the structural color expression regions R1a to R1f). More specifically, the incident / reflected light limiting unit 2 according to the eighth embodiment includes a bundled optical fiber in which optical fibers extending along the thickness direction of the image display sheet 1 are fixed in a bundle. Microlenses 8a to 8f are arranged on the opening end face of the optical fiber. Further, the diameters of the microlenses 8a to 8f are the same as the diameters of the open end faces of the optical fibers. In other words, in the microlens, the diameter and pitch of the opening end face of the optical fiber are matched. By doing so, it is possible to prevent the resolution of the displayed image from being lowered, and the observer can observe the image at a wide angle.
Note that the microlens array 8 only needs to widen the opening angle of incident light and diffuse the reflected light to widen the viewing angle. For example, the material, shape, and number of the microlenses 8a to 8f are not limited.

[Ninth Embodiment]
Hereinafter, the configuration of the image display device 18 according to the ninth embodiment will be described. FIG. 11 is a conceptual cross-sectional view showing the configuration of the image display device 18 according to the ninth embodiment of the present invention. As shown in FIG. 11, the structure of the image display device 18 is substantially the same as the structure of the image display device 15 according to the sixth embodiment described above, but the opening angle of the incident light is set on the incident / reflected light limiting unit 2. It differs from the image display device 15 in that it includes a light scattering sheet 9 that spreads and diffuses reflected light. Therefore, in the ninth embodiment, the light scattering sheet 9 will be mainly described, and description of other components will be omitted.

(Light scattering sheet 9)
The light scattering sheet 9 is a sheet-like member for widening the opening angle of incident light and diffusing reflected light to widen the viewing angle. The light scattering sheet 9 is arranged so as to cover the image display side of the incident / reflected light limiting unit 2. By doing so, the observer can observe the image at a wider angle.
Note that the light scattering sheet 9 may be any material or shape as long as it can widen the opening angle of incident light and diffuse the reflected light to widen the viewing angle. Moreover, the size does not ask | require.
Moreover, the light-scattering sheet 9 is not limited to what diffuses reflected light as mentioned above. For example, the light scattering sheet 9 may have a function of diffusing both incident light and reflected light. In that case, the light scattering sheet 9 preferably has a high light transmittance while having an appropriate diffusibility. When light is diffused excessively, the luminance of the structural color that can be visually recognized decreases. Examples of the material of the light scattering sheet 9 having a function of diffusing incident / reflected light include, for example, a glass plate (ground glass) whose surface is roughened, a light scattering film, a light scattering sheet, a translucent film, tracing paper, and glassine paper. And paraffin paper.

(effect)
(1) The image display devices 10 to 18 are set in advance for the image display sheet 1 having the structural color expression region R1 and the surface S1 that is installed on the image display side of the structural color expression region R1 and is located on the image display side. At least the incident light 3a incident at an angle and the incident light 3a that selectively reflects the reflected light 3b reflected from a part of the structural color expression region R1 of the incident light 3a.
With such a configuration, the incident angle of the incident light 3a and the reflection angle of the reflected light 3b can be set to preset angles. For this reason, even when the observation angle of the observer is different, the optical path length in the image display sheet 1 does not change, and the wavelength of the interfering light does not change. Thereby, it is possible to prevent the structural colors displayed on the image display devices 10 to 18 from changing.
Moreover, if it is such a structure, if the light source of the incident light 3a will be sunlight, the electric power for displaying an image will not be required.
In addition, with the structural color display according to one embodiment of the present invention, even if the position of the light source, that is, the incident angle of light changes, an image displayed using the structural color is prevented from changing. You can also
Further, in the structural color display according to one aspect of the present invention, for example, even when incident light is multiple reflected light, that is, when a part of the incident light is reflected by an outer wall or the like installed outdoors, It is also possible to prevent luminance unevenness of an image displayed using structural colors.

(2) The incident / reflected light limiting unit 2 of the image display devices 10 to 18 reflects the incident light 3a incident on the surface S1 at an angle in the range of 80 ° to 90 ° and the angle within the angular range. The reflected light 3b is selectively transmitted.
With such a configuration, the image can be observed from a direction substantially perpendicular to the surface S1, and thus the visibility of the displayed image can be further improved. Also, since the viewing angle can be narrowed, peeping can be prevented (privacy view guard).

(3) The incident / reflected light restricting unit 2 of the image display devices 10 to 18 includes a urexite disposed so as to be able to transmit incident light 3a incident along the thickness direction of the image display sheet 1, and a thickness direction of the image display sheet 1. At least one of a bundled optical fiber in which optical fibers extending along the bundle are fixed in a bundle is provided.
Urexite and bundled optical fibers can be obtained relatively easily. Therefore, with such a configuration, the manufacturing cost of the incident / reflected light limiting unit 2 can be reduced. Therefore, the manufacturing cost of the entire image display device can be reduced.

(4) The image display device 11 includes a sheet thickness adjustment unit 4 that adjusts the thickness of the image display sheet 1 in the structural color expression region R1 at a position facing the incident reflection light limiting unit 2 with the structural color expression region R1 interposed therebetween. ing.
With such a configuration, since the thickness of the image display sheet 1 in the structural color expression region R1 can be freely adjusted, the color of the structural color to be expressed can be variously changed.

(5) The sheet thickness adjusting unit 4 of the image display device 11 includes an electrode that contacts the image display sheet 1, and the image display sheet 1 is formed of a voltage-responsive polymer gel whose volume changes according to voltage. Yes. The sheet thickness adjusting unit 4 includes a heating unit capable of heating the image display sheet 1, and the image display sheet 1 is formed of a thermoresponsive polymer gel whose volume changes according to heat. The sheet thickness adjusting unit 4 includes a light irradiation unit that can irradiate the image display sheet 1 with light, and the image display sheet 1 is formed of a photoresponsive polymer gel whose volume changes according to light.
With such a configuration, the thickness d1 of the image display sheet 1 can be freely adjusted by applying a voltage to the electrodes included in the sheet thickness adjusting unit 4. Therefore, it is possible to change the color of the structural color that is expressed in various ways, and it is possible to further increase the speed (response speed) of changing the color of the structural color. In addition, there exists an effect similar to this also by the heating with respect to the image display sheet 1, or light irradiation.

(6) The image display sheet 1 of the image display device 12 is a multilayer structure in which structural color expression layers 1a to 1c that express a structural color are stacked along the thickness direction of the image display sheet 1, and the structural color expression region R1 The thickness of each of the structural color developing layers 1a to 1c is an integral multiple of the thickness of the reference layer when any one of the laminated structural color developing layers 1a to 1c is used as the reference layer.
With such a configuration, a structural color with improved monochromaticity can be expressed.

(7) The structural color developing layers 1a to 1c of the image display device 12 are all formed of the same material.
With such a configuration, a structural color with improved monochromaticity can be produced at low cost.

(8) The image display device 15 further includes a plano-convex lens 6 which is disposed so as to cover the image display side of the incident / reflected light limiting unit 2 and has a plane and a convex surface located on the back side of the plane. The 6 plane faces the incident / reflected light limiting unit 2 side.
With such a configuration, since the incident light 3a and the reflected light 3b can be easily scattered, the viewing angle can be easily widened.

(9) The image display device 16 includes a microlens array 7 including a plurality of microlenses 7a to 7h.
With such a configuration, the incident light 3a and the reflected light 3b can be reliably scattered, so that the viewing angle can be more reliably widened.

(10) The incident / reflected light limiting unit 2 of the image display device 17 includes a bundled optical fiber in which optical fibers extending in the thickness direction of the image display sheet 1 are fixed in a bundle, and each opening of the optical fiber. Microlenses 8a to 8f are disposed on the end face, and the diameters of the microlenses 8a to 8f are the same as the diameter of the opening end face of the optical fiber.
With such a configuration, since the incident light 3a and the reflected light 3b can be easily scattered, the viewing angle can be further widened.

(11) The image display device 18 further includes a light scattering sheet 9 that scatters the incident light 3a and the reflected light 3b, which is disposed so as to cover the image display side of the incident / reflected light limiting unit 2.
With such a configuration, since the incident light 3a and the reflected light 3b can be easily scattered, the viewing angle can be easily widened.

(Modification)
(1) In the above embodiment, the incident / reflected light limiting unit 2 having a plurality of incident / reflected light transmission regions R2a to R2f has been described. However, the present invention is not limited to this. For example, the incident / reflected light limiting unit 2 may have a single incident / reflected light transmission region R2. Even in this case, the above-described effects can be achieved.

(2) In the above-described embodiment, the incident / reflected light limiting unit 2 in which the incident / reflected light transmission regions R2 (R2a to R2f) are located apart from each other has been described. However, the present invention is not limited to this. For example, the incident / reflected light transmission regions R2 (R2a to R2f) may be adjacent to each other. Even in this case, the above-described effects can be achieved.

(3) In the above embodiment, the sheet thickness adjusting unit 4 (4a to 4f) including the electrode in contact with the image display sheet 1 has been described, but the present invention is not limited to this. The sheet thickness adjusting unit 4 (4a to 4f) only needs to change the sheet thickness of the structural color expression region R1 (R1a to R1f). For example, the sheet thickness adjustment unit 4 (4a to 4f) includes a pump and the like, and the structural color expression region R1 (R1a to R1f) is added in the sheet thickness direction using the sheet thickness adjustment unit 4 (4a to 4f). The sheet thickness of the structural color expression region R1 (R1a to R1f) may be changed by applying pressure or reduced pressure. Even in this case, the above-described effects can be achieved.
Further, the sheet thickness adjusting unit 4 (4a to 4f) may be, for example, a light irradiation device capable of irradiating light or a heating device capable of applying heat. Even in this case, the above-described effects can be achieved. Here, when the sheet thickness adjusting unit 4 (4a to 4f) is a light irradiation device, the image display sheet 1 is preferably formed of, for example, a photoresponsive polymer gel. When the sheet thickness adjusting unit 4 (4a to 4f) is a heating device, the image display sheet 1 is preferably formed of, for example, a temperature-responsive polymer gel.
Further, the sheet thickness adjusting unit 4 (4a to 4f) may be an apparatus capable of imparting distortion such as bending, pulling, and compression to the image display sheet 1.

(4) In the above embodiment, the image display sheet 1 composed of the three structural color developing layers 1a to 1c has been described. However, the present invention is not limited to this. For example, the image display sheet may be a multilayer structure, and may be a structure in which two structural color developing layers are stacked, or a structure in which four or more structural color developing layers are stacked. . Even in this case, the above-described effects can be achieved.

(5) In the above embodiment, the case where the reference layer is the structural color developing layer 1a has been described, but the present invention is not limited to this. For example, the reference layer may be the structural color expression layer 1b or the structural color expression layer 1c. Even in this case, the above-described effects can be achieved.

(6) In the above embodiment, the case where the structural color developing layers 1a to 1c are all formed of the same material has been described, but the present invention is not limited to this. For example, each of the structural color developing layers 1a to 1c may be formed of different materials. Even in this case, the above-described effects can be achieved.

(7) In the above embodiment, the case where the plano-convex lens 6 and the microlens arrays 7 and 8 are used to widen the viewing angle of the displayed image has been described, but the present invention is not limited to these. . A lens other than a plano-convex lens or a microlens array may be used as long as the viewing angle of the displayed image can be widened. Even in these cases, the above-described effects can be achieved.

(8) In the above embodiment, the case where the frame 5 is provided between the image display sheet 1 and the incident / reflected light limiting unit 2 or embedded in the image display sheet 1 has been described. It is not limited. Even if the frame 5 is not provided, the above-described effects can be achieved. Further, since the frame 5 is not provided, the structural color expression regions R1a to R1f can be made wider.

(9) In the above-described embodiment, the image display apparatus that displays an image using structural colors has been described. However, the present invention is not limited to these. For example, the image display device described in the above embodiment may be incorporated in an image display medium and used as an image display object. More specifically, a poster or calendar can be created by incorporating the image display device described in the above embodiment into paper.

(10) In the above embodiment, the case where, for example, urexite or a bundled optical fiber is used as the incident / reflected light limiting unit 2 is described, but the present invention is not limited to these. For example, instead of the above-described urexite or bundled optical fiber, as the incident / reflected light limiting portion 2, a glass plate (ground glass) whose surface is roughened, a light scattering film, a light scattering sheet, a translucent film, tracing paper, Glassine paper, paraffin paper, or the like may be used. Even when these materials are used, the above-described effects can be obtained.
Further, as the incident / reflected light limiting unit 2, a Fresnel lens may be used instead of the above-described urexite or bundled optical fiber. Even when this lens is used, the above-described effects can be obtained.

(Other variations)
A configuration of a display other than the display according to the above-described modification will be described below. Even the following display can solve the problems of the present application.
・ Modification A
A display on which an image is displayed with a structural color, the display including an image display sheet that displays an image with a structural color, the image display sheet including a structural color expression region and the image of the structural color expression region A structural color display comprising an incident / reflected light limiting unit disposed on the display side of the display.

・ Modification B
Incident light incident on the incident / reflected light restricting portion within a predetermined incident angle range with respect to the surface of the structural color expression area, and reflected light reflected by a part of the structural color expression area of the incident light And a structural color display using an incident / reflected light restricting portion that selectively transmits light.

・ Modification C
A structural color display in which the incident / reflected light limiting portion is constituted by a bundle of optical fibers or a urexite plate.

・ Modification D
A structural color display in which the incident / reflected light limiting portion is a bundled optical fiber, and the bundled optical fiber is a tapered bundled optical fiber.

・ Modification E
A structural color display in which the structural color expression region is any one of a colloidal crystal structure, an inverse opal structure, a multilayer structure, and a lamella structure.

・ Modification F
A structural color display in which the structural color expression region has a Bragg period based on a multilayer structure and each layer is made of the same material.

・ Modification G
The image display sheet further includes a stimulus applying unit that applies a stimulus to the structural color expression region at a position facing the incident / reflected light limiting unit with the structural color expression region interposed therebetween, or across the structural color expression region. A stimulus-responsive structure in which the Bragg period is changed by any one of an electric field, light, deformation (strain / stress), heat, or magnetism applied by the stimulus applying unit. Structural color display composed of color materials.

・ Modification H
The image display sheet further includes a plano-convex lens having a plane and a convex surface located on the back side of the plane, and the plano-convex lens is arranged such that the plane faces the incident reflection light limiting unit side, and the convex surface A structural color display arranged to face the image display side (viewing side) and to cover the display side of the image.

・ Modification I
A structural color display in which the plano-convex lens is a microlens array composed of a plurality of microlenses.

・ Modification J
The incident / reflected light limiting portion is configured by a bundled optical fiber, the diameter of the microlens configuring the microlens array is the same as the diameter of the optical fiber configuring the bundled optical fiber, and each of the optical fibers A structural color display in which the microlens is disposed on the opening end face.

・ Modification K
A structural color display further comprising a light scattering sheet arranged to cover the image display side of the incident / reflected light restricting portion and diffusing the incident / reflected light and the reflected light.

・ Modification L
An image display object including the structural color display according to any one of Modifications A to K.

<Experimental example>
Examples of experiments are shown below.
<Outline of structural color measuring device>
FIG. 15 is a schematic diagram of the structural color measuring apparatus 30 used for demonstrating the effects of the present invention. The main part of the apparatus is composed of a light source device 31, a color luminance meter 32, a slider 33 for adjusting the light reception angle (observation angle α) of the color luminance meter 32, a test piece installation base 35, and a support base 34. . The upper surface of the support table 34 is kept horizontal, and the slider 33 is placed perpendicular to the upper surface of the support table 34. The outer periphery of the slider 33 has a semicircular arc shape, and the color luminance meter 32 can change the observation angle α with respect to the center of the test piece installation base 35 along the slider 33 in the range of 0 ° to about 40 °. The light source device 31 is on a plane perpendicular to the slider 33 including the center of the test piece installation table 35, and the incident angle (β) is set to 25 ° with respect to the center of the test piece installation table 35.

The direction indicator mark 38 is provided on the test piece mounting base 35. The direction indication mark 38 indicates the direction of the test piece mounting base 35 to be installed on the structural color measuring device 30. In each measurement, since the test piece is placed on the test piece setting table 35 in accordance with the direction indication mark 38, it is possible to correctly grasp the direction of the light source device 31 with respect to the measurement object and the direction in which the color luminance meter 32 moves. It becomes possible.

<Light source device 31>
In FIG. 15, the light source device 31 includes a box 311 and a cylinder 312 having a black inner surface, and a high color rendering fluorescent tube (not shown) is accommodated in the box 311. Of the light emitted from the fluorescent tube, only the light that has passed through the tube 312, that is, the light that is substantially parallel to the axis of the tube 312, reaches the object to be measured.
FIG. 16 shows a spectrum distribution obtained by actually measuring the light emitted from the cylinder 312 of the light source device 31 with a spectral radiance meter from the front. The spectral radiance meter is a spectral radiance meter (CS-2000A) manufactured by Konica Minolta.
The specifications of the fluorescent tube used in the light source device 31 are as follows.
Manufacturer: Mitsubishi Electric Lighting Co., Ltd.
Name: High color rendering color rendering AAA daylight white fluorescent tube Model: FL20S / N-EDL / NU
Color temperature: 5000K (Manufacturer's data sheet value)
Color rendering index (Ra): 99 (data sheet provided by manufacturer)

<Color luminance meter 32>
Chromaticity (x, y) and luminance (Lv) were measured using a two-dimensional color luminance meter (CA-2500) manufactured by Konica Minolta. In each experiment, numerical values of the chromaticity and luminance of the surface of the measurement object are obtained by the color luminance meter 32, and these are obtained on the surface image of the measurement object projected by the color luminance meter 32 in each measurement scene. A measurement area is set by surrounding a desired position in a rectangle with squares, and an average value of chromaticity and an average value of luminance are obtained in the area.

<Standard gray plate for comparison>
As a “standard gray plate for comparison”, an 18% standard reflector made by Nikon Corporation was used. This is to measure the chromaticity and luminance of the standard reflector together with the measurement object, and to judge that the measurement has proceeded correctly from the values obtained here.

<Particle type structural color sheet 36>
In some experimental examples, a sheet-like test piece (= elastomer sheet) composed of the following structural color materials was used.
In this test piece, a soft sheet in which monodispersed glass fine particles (particle diameter: 0.18 μm) having a refractive index of 1.45 are uniformly dispersed in an elastomer phase having a refractive index of 1.50 is laminated and fixed on a black rubber-like base sheet. A rectangular elastomer sheet having a thickness of about 2 mm, a vertical length of about 30 mm, and a horizontal length of about 20 mm.

This elastomer sheet is a structural color material whose hue changes depending on the viewing angle.
Hereinafter, this elastomer sheet exhibiting a structural color is referred to as a particle-type structural color sheet 36.

<Multilayer structure color plate 37>
In this experiment, in order to further investigate the effect of the incident / reflected light limiting unit 2, the following multilayer structural color plate 37 was also used.
The multilayer structural color plate 37 was prepared using the following commercially available notch filter. The specifications of the notch filter used are as follows.
Name: Notch filter Model number: NF-25C05-47-633
Manufacturer: Sigma Hikari Co., Ltd.
Characteristics: Cut wavelength 633 nm, transmission band wavelengths 475 to 597 nm and 669 to 850 nm, transmittance 90%

This notch filter reflects light of a wavelength corresponding to the incident angle of the light and transmits other light only during regular reflection. This notch filter has a multilayer structure in which two kinds of fine particles having different refractive indexes are alternately laminated, and has a property of not transmitting light in a specific wavelength range. Specifically, the notch filter has transmission band wavelengths of 475 to 597 nm and 669 to 850 nm in front view (incidence angle 0 °). Accordingly, when viewed from the front, light (red) having a wavelength of 600 to 668 nm has a characteristic of being reflected toward the front without being transmitted.

¡Multi-layered structural color plate 37 was created by applying black coating on one side of the notch filter. A black coating was applied to the back of the notch filter so that light with a transmission band wavelength (ranging from 475 to 597 nm and 669 to 850 nm) was absorbed by the black coating. In this way, the multilayer structural color plate 37 has a characteristic that the light having a wavelength corresponding to the incident angle of the light is specularly reflected and the other light is absorbed by the black paint.

In Experimental Examples 1 to 4 below, the following plates were used as specific configurations of the incident / reflected light limiting unit 2.
<Incoming / reflecting light limiting plate>
Bundled optical fiber plate OP1 (hereinafter sometimes simply referred to as OP1): thickness of about 11 mm
・ Urexite plate OP2 (hereinafter sometimes simply referred to as OP2): thickness of about 7 mm
Bundled optical fiber plate OP3 (hereinafter sometimes referred to as high performance plate OP3): about 3 mm thick
In either case, the fiber axis or crystal axis is oriented in the direction perpendicular to the plate surface. The “high performance” of the high performance plate OP3 means that the performance is higher than that of OP1. More specifically, the high performance means that the orientation is higher than that of OP1 and the light transmittance is high.

Further, in Experimental Example 5, the following light diffusion sheet DP1 was used as a specific configuration of the incident / reflected light limiting unit 2.

<Light diffusion sheet DP1>
The following translucent film was used as the light diffusion sheet DP1.
-Translucent film: (3M Company's mending tape, Scotch tape, "Scotch" is a registered trademark of 3M Company)

[Experimental Example 1]
The following experiment was conducted by combining the particle-type structural color sheet 36 and the bundled optical fiber plate OP1. Hereinafter, a description will be given with reference to FIGS. 15 and 17.
The structural color measuring device 30 was placed in a dark room, and the particle type structural color sheet 36 was fixed to a test piece mounting table 35 placed on the structural color measuring device 30. Further, OP1 was placed on a part of the upper surface of the particle type structural color sheet 36. Next, the “standard gray color plate for comparison” was pasted at the position of the measurement position P1, and on the other hand, the same sheet piece as the particle type structural color sheet 36 was pasted at the position of the measurement position P2.

After the above preparation, light is emitted from the light source device 31 to the test piece mounting table 35, and the surface of the “standard gray plate for comparison” (measurement position P1) and the surface of the particle-type structural color sheet 36 (measurement position). P3), the surface of the particle-type structural color sheet placed on OP1 (measurement position P2), the surface of OP1 by the reflected light of the particle-type structural color sheet 36 that has passed through OP1 (measurement position P4), The chromaticity and luminance at each position were measured by setting the observation angle α of the color luminance meter 32 to 0, 10, 20, 30, 40 °.

The results are shown in Table 1. Based on Table 1, the locus of the chromaticity change accompanying the change in the observation angle α is shown as an xy chromaticity diagram in FIG. 18, and the change in luminance is shown in FIG.
First, looking at the chromaticity and luminance of the “comparative standard gray color plate” (measurement position P1), these values hardly change, indicating that this experiment was performed correctly.
Next, as shown in FIG. 18, when the chromaticities (measurement positions P2, P3) on the surface of the particle-type structural color sheet 36 are observed, these are strongly dependent on the observation angle α, and α is still 10 °. Regardless, the chromaticity changes abruptly, and it is clear that the “redness” is lost at 30 °.

On the other hand, the chromaticity of the surface of OP1 (measurement position P4) due to the reflected light of the particle-type structural color sheet 36 that is transmitted through and reflected by the bundled optical fiber plate OP1 is less dependent on the observation angle and α is 30 °. The red color is still maintained.

From the above, it is clear that the bundled optical fiber plate OP1 suppresses the observation angle dependency of the chromaticity of the structural color.

When the luminance (FIG. 19) is described, the luminance of the surface of the particle-type structural color sheet 36 at the measurement positions P2 and P3 decreases sharply when the observation angle α exceeds 10 °, whereas the bundled optical fiber plate OP1 is reduced. The brightness of the surface of OP1 (measurement position P4) by the reflected light of the particle-type structural color sheet 36 that has passed through maintains a high value from the observation angle of 20 ° to the observation angle of 40 °.
This is also an effect of the bundled optical fiber plate OP1.

Note that, in any range of the observation angle α in this experimental example, the observation angle dependency of the chromaticity and luminance on the surface of the particle-type structural color sheet 36 is hardly affected by the difference between the measurement positions P2 and P3. From this point, it is apparent that the effect of suppressing the dependence of the structural color of the bundled optical fiber plate OP1 on the observation angle is not due to the difference in measurement position (P3 vs. P4).

[Experiment 2]
Hereinafter, an experiment was performed by combining the particle-type structural color sheet 36 and the urexite plate OP2.
A structural color measurement test was conducted in the same manner as in Experimental Example 1 except that a urexite plate OP2 was used instead of the bundled optical fiber plate OP1.

The results are shown in Table 2, FIG. 20 and FIG. Similar to Experimental Example 1, it can be seen that the observation angle dependency of the structural color is improved and the luminance is maintained at a high value by the urexite plate OP2.

[Experiment 3]
The bundled optical fiber plate OP1 and the high performance plate OP3 were placed adjacent to each other on the particle-type structural color sheet 36, and the following experiment was conducted for the purpose of comparing the difference in characteristics between the two. The comparison was visually.
In Experimental Example 1, OP1 and high-performance plate OP3 were placed adjacent to each other on the particle-type structural color sheet 36. At this time, the light source device 31 maintained the position in Experimental Example 1, and the observation angle dependency of the structural color of the test piece viewed through OP1 and OP3 was observed by visual observation instead of the color luminance meter 32. The position of the naked eye is substantially the same as the position of the color luminance meter 32 in Experimental Example 1.

As a result, when the observation angle α is 30 °, in the case of the bundled optical fiber plate OP1, the red saturation of the structural color is lowered (smoothed), whereas in the case of the high-performance plate OP3, the saturation is reduced. A high red color was visible.

[Experimental Example 4]
The following experiment was performed using a combination of the multilayer structural color plate 37 and the bundled optical fiber plate OP1. That is, in Experimental Example 1, the test color was changed from the particle type structural color sheet 36 to the multilayer type structural color plate 37, and the structural color was measured in the same manner as the others. The measurement positions are as shown in FIG.

The results are shown in Table 3, FIG. 23, and FIG.
Here, the multilayered structural color plate 37 used in this experiment has a characteristic that does not reflect light except for regular reflection. That is, the incident angle of light from the light source device 31 with respect to the surface of the multilayer structural color plate 37 and the angle (reflection angle) of the light reflected on the surface of the multilayer structural color plate 37 and observed by the color luminance meter 32. Unless they are equal, the surface of the multilayer structural color plate 37 has very low brightness and appears black.

Therefore, as is clear from the positional relationship among the light source device 31, the color luminance meter 32, and the test piece installation base 35 in the structural color measuring device 30 of the present experiment, in this experiment, the light irradiated from the light source device 31 has a multilayer structure. It is reflected by the surface of the color plate 37 and is not captured by the color luminance meter 32 by regular reflection (see FIG. 30). For this reason, the surface of the multilayer structural color plate 37 always shows extremely low luminance (measurement position P3).

On the other hand, in this experimental example, although the regular reflection condition is never satisfied, the upper surface (measurement position P4) of the bundled optical fiber plate OP1 always shows high brightness and clear red. it can.

That is, even if the multilayer structural color plate 37 has a very narrow angle range in which the reflected light can be visually recognized, the bundled optical fiber plate OP1 is provided on the multi-layer structural color plate 37, so that the position of the light source and the position of the observer are Even when there is no regular reflection relative to the surface of the mold structure color plate 37, the structure color of the multilayer structure color plate 37 can be visually recognized.

The above effect means that the structural color display of the present invention has less restrictions on arrangement and installation due to the position of the observer and the light source (or the angle of the light source), and has a high degree of design freedom. This greatly increases the practical value of the structural color display.

At the same time, as in Experimental Example 1, the bundled optical fiber plate OP1 exhibits the effect of suppressing the observation angle dependency even for the multilayer structural color plate 37 having a narrow angle range in which the reflected light can be visually recognized. There was found.

[Experimental Example 5]
The following experiment was conducted using a combination of the multilayer structure color plate 37 and the light diffusion sheet DP1. That is, in Experimental Example 4, the measurement was performed in the same manner except that the light diffusion sheet DP1 was used instead of the bundled optical fiber plate OP1. The measurement position is as shown in FIG.

The results are shown in Table 4, FIG. 26, and FIG.
From this result, as for the light diffusion sheet DP1, as in Experimental Example 4, the multilayer light source sheet 37 and the observer position of the multilayer structural color plate 37 having a very narrow angle range in which the reflected light can be visually recognized are multilayered. Even when there is no regular reflection position relative to the surface of the structural color plate 37, the upper surface (measurement position P4) of the multilayer structural color plate 37 always has a high brightness and a clear red color. I was able to.

Further, similarly to Experimental Example 4, it was found that the light diffusion sheet DP1 also exerts an effect of suppressing the observation angle dependency on the multilayered structural color plate 37 having a narrow angle range in which the reflected light can be visually recognized. .

The light diffusion sheet DP1 is an inexpensive material and is advantageous for practical use in terms of cost.

Although the present invention has been described with reference to a limited number of embodiments and modifications, the scope of rights is not limited thereto, and modifications of each embodiment based on the above disclosure are obvious to those skilled in the art. That is.

DESCRIPTION OF SYMBOLS 1 Image display sheet 1a-1c Structural color expression layer 2 Incident reflected light restriction | limiting part 3a Incident light 3b Reflected light (structural color)
4 Sheet thickness adjusting unit 4a to 4f Sheet thickness adjusting unit 5 Pixel division frame (frame)
6 Plano-convex lens 7 Micro lens array 7a to 7h Micro lens 8 Micro lens array 8a to 8f Micro lens 9 Light scattering sheet 10 to 18 Image display device 20 Image display device 30 Structural color measuring device 31 Light source device 311 Box 312 Tube 32 Color luminance Total 33 Slider 34 Support stand 35 Test piece installation stand 36 Particle type structural color sheet 37 Multilayer type structural color plate 38 Direction indication mark α Observation angle β Light source incident angle L _N normal P1 Measurement position of chromaticity and luminance in the experimental example P2 measurement positions chromaticity and luminance at the measurement position P4 experimental example of the chromaticity and the luminance at the measurement position P3 experimental example of the chromaticity and luminance in experimental example D ₁ of the first layer in a multilayer structure structural color material thickness D ₂ Multi-layer structure Wavelength refractive index lambda _peak reflectivity of the second layer in the first layer refractive index n ₂ multilayer structural color materials in the thickness n ₁ multilayer structural color materials of the second layer in the color material is maximum θ Observation angle D _c Distance between crystal planes in colloidal crystal structure color material D _o Stimulus responsive colloid crystal structure color material before interstitial distance D _S Stimulus responsive colloid crystal structure color material during the distance n _D colloid dispersing medium refractive index R red structural color G green structural color B blue structure (continuous phase) in the refractive index n _M colloidal crystal structural color materials of the dispersed particles in the crystal structure color material (dispersed phase) Color R1 Structural color expression region R1a to R1f Structural color expression region R2 Incident / reflected light transmission region R2a to R2f Incident / reflected light transmission region S1 surface (image display side surface)
S2 side (back side)
d1 to d2 Sheet thickness

Claims (13)

1. A structural color display in which an image is displayed by a structural color,
   An image display sheet having a structural color expression region that is a region expressing the structural color;
   Incident light that is installed on the image display side of the structural color expression region and is incident at a predetermined angle with respect to the surface of the structural color expression region located on the image display side, A structural color display comprising at least an incident / reflected light limiting unit that selectively transmits reflected light reflected by a part of the structural color expression region.
2. The incident / reflected light limiting unit includes the incident light incident at an angle within a range of 80 ° to 90 ° with respect to the surface of the structural color expression region, and the reflected light reflected at an angle within the range. The structural color display according to claim 1, wherein the structural color display is selectively transmissive.
3. The incident / reflected light limiting unit fixes a urexite disposed so as to transmit incident light incident along a thickness direction of the image display sheet and an optical fiber extending along the thickness direction of the image display sheet in a bundle shape. The structural color display according to claim 1, comprising at least one of a bundle of optical fibers.
4. A structural color display in which an image is displayed by a structural color,
   An image display sheet having a structural color expression region that is a region expressing the structural color;
   Urexite installed on the image display side of the structural color expression region and arranged to transmit incident light incident along the thickness direction of the image display sheet, and light extending along the thickness direction of the image display sheet A structural color display comprising: an incident / reflected light limiting unit including at least one of a bundle of optical fibers in which fibers are fixed in a bundle.
5. The sheet thickness adjusting unit further adjusts the thickness of the image display sheet in the structural color developing region at a position facing the incident / reflected light restricting unit across the structural color developing region. The structural color display according to claim 4.
6. The sheet thickness adjusting unit includes any one of an electrode that contacts the image display sheet, a heating unit that can heat the image display sheet, and a light irradiation unit that can irradiate the image display sheet with light.
   The image display sheet is a voltage-responsive polymer gel whose volume changes according to a voltage or an electric field applied to the electrodes, a heat-responsive polymer gel whose volume changes according to heat from the heating unit, 6. The structural color display according to claim 5, wherein the structural color display is formed of any one of photoresponsive polymer gels whose volume changes in response to light from the light irradiation unit.
7. The image display sheet is a multilayer structure in which a structural color expression layer that expresses the structural color is laminated along the thickness direction of the image display sheet,
   The thickness of each of the structural color expression layers in the structural color expression region is an integral multiple of the thickness of the reference layer when any one of the stacked structural color expression layers is used as a reference layer. The structural color display according to any one of claims 1 to 6, wherein the structural color display is characterized.
8. 8. The structural color display according to claim 7, wherein each layer of the structural color expression layer is formed of the same material.
9. A plano-convex lens having a flat surface and a convex surface located on the back surface side of the flat surface, disposed so as to cover the image display side of the incident / reflected light limiting unit;
   9. The structural color display according to claim 1, wherein the plane of the plano-convex lens faces the incident / reflected light restricting portion side.
10. The structural color display according to claim 9, wherein the plano-convex lens is a microlens array including a plurality of microlenses.
11. The incident / reflected light limiting unit includes a bundled optical fiber in which optical fibers extending along the thickness direction of the image display sheet are fixed in a bundle.
    The microlens is arranged on each opening end face of the optical fiber,
    The structural color display according to claim 10, wherein the diameter of the microlens is the same as the diameter of the opening end face of the optical fiber.
12. The light scattering sheet for diffusing the incident light and the reflected light, which is disposed so as to cover the display side of the image of the incident / reflected light limiting unit, further comprises: The structural color display according to any one of the preceding claims.
13. An image display object comprising the structural color display according to any one of claims 1 to 12.

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