WO2024147337A1

WO2024147337A1 - Optical element and light guide plate

Info

Publication number: WO2024147337A1
Application number: PCT/JP2023/047245
Authority: WO
Inventors: 幸夫谷口; 正古川; 晃次郎大川; 俊安達
Original assignee: 大日本印刷株式会社
Priority date: 2023-01-06
Filing date: 2023-12-28
Publication date: 2024-07-11

Abstract

An optical element 20 is used in the display of a 3D display object. The optical element 20 comprises a prism 30. The prism includes: a bottom surface 31; and a plurality of lens surfaces 32 which are inclined with respect to the bottom surface 31. The lens surfaces 32 are provided with an uneven shape 35.

Description

Optical elements, light guide plates

This disclosure relates to an optical element used to display a three-dimensional object, and a light guide plate having the optical element.

Optical elements used to display three-dimensional objects, such as that described in Japanese Patent No. 4611747, are known. The optical element described in Japanese Patent No. 4611747 includes multiple lens surfaces. The light from a light source is reflected by the lens surfaces, allowing a three-dimensional object to be observed.

　Patent Publication No. 4611747 only displays three-dimensional objects, and does not disclose any ideas for improving the design of the displayed objects. The present disclosure aims to improve the design of three-dimensional objects displayed by optical elements.

One embodiment of the present disclosure relates to the following [1] to [13].
[1]
An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
The optical element has an uneven surface on the lens surface.
[2]
The optical element according to [1], wherein the uneven shape is non-uniform among the plurality of lens surfaces.
[3]
An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
The prism is an optical element including a scatterer.
[4]
The optical element according to [3], wherein the scattering matter is distributed non-uniformly.
[5]
An optical element used to display a three-dimensional display object,
a prism including a base surface and a plurality of lens surfaces inclined relative to the base surface;
a scattering layer overlying the prism.
[6]
The optical element according to [5], wherein the light scattering property of the scattering layer is non-uniform.
[7]
An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
the prism includes a plurality of polygonal sections;
An optical element, wherein in a given polygonal region, the lens surfaces extend linearly in a first direction and are arranged in a second direction non-parallel to the first direction.
[8]
The optical element according to [7], wherein the lens surfaces of adjacent polygonal regions are connected.
[9]
The optical element described in [8], wherein the sum of the areas of the lens surfaces in the polygonal sections where the normal direction of the lens surfaces forms an angle of 3.7° or more with the lens surface of any of the adjacent polygonal sections is 10% or more of the sum of the areas of the lens surfaces of the entire prism.
[10]
The optical element according to any one of [1] to [9], further comprising a light modulating layer having a non-uniform color or transmittance.
[11]
An optical element used to display a three-dimensional display object,
a prism including a base surface and a plurality of lens surfaces inclined relative to the base surface;
a light modulating layer overlying the prism;
An optical element, wherein the light modulating layer is non-uniform in color or transmittance.
[12]
The optical element according to any one of [1] to [11], further comprising a reflective layer or a partially reflective layer provided so as to cover the lens surface.
[13]
The optical element according to any one of [1] to [12], wherein the lens surfaces are arranged along a certain closed curve.
[14]
A light guide plate comprising the optical element according to any one of [1] to [13].

The present disclosure makes it possible to improve the design of three-dimensional objects displayed using optical elements.

FIG. 1 is a cross-sectional view showing a first example of an optical element according to the present disclosure. FIG. 2 is an enlarged cross-sectional view showing a prism in the optical element. FIG. 3 is a cross-sectional view showing a second example of the optical element of the present disclosure. FIG. 4 is a cross-sectional view showing a third example of the optical element of the present disclosure. FIG. 5 is a cross-sectional view showing a fourth example of the optical element of the present disclosure. FIG. 6 is a cross-sectional view showing a fifth example of the optical element of the present disclosure. FIG. 7 is a cross-sectional view showing a sixth example of the optical element of the present disclosure. FIG. 8 is an enlarged view showing an example of a top view of an optical element. FIG. 9 is a diagram for explaining the difference in appearance of a displayed object when the position from which the displayed object is observed is changed. FIG. 10 is a cross-sectional view showing a first example of a light guide plate including an optical element. FIG. 11 is a cross-sectional view showing a second example of a light guide plate including an optical element. FIG. 12 is a cross-sectional view showing a third example of a light guide plate including an optical element. FIG. 13 shows an example of data of an object to be displayed using an optical element. FIG. 14 shows an example of a display object that is assumed to be displayed using optical elements. FIG. 15 shows an example of a display object that is assumed to be displayed using optical elements. FIG. 16 shows an example of an object displayed using an optical element. FIG. 17 is a diagram showing a modification of the optical element when viewed from above.

Below, an embodiment of the present disclosure will be described with reference to the drawings. The scale and aspect ratios in the drawings attached to this specification have been altered and exaggerated from the actual ones for ease of illustration and understanding.

In this specification, the terms "layer," "sheet," and "film" are not distinguished from one another solely on the basis of differences in name. For example, the term "layer" is a concept that includes members that may be called films or sheets.

　Terms used in this specification that specify shapes and geometric conditions and their degrees, such as "parallel," "orthogonal," and "same," as well as values of lengths and angles, are not limited to their strict meanings and are interpreted to include the range of degrees to which similar functions can be expected.

1 to 16 are diagrams for explaining an embodiment of the present disclosure. Each of FIG. 1 and FIG. 3 to FIG. 7 shows a different example of the optical element 20 of the present disclosure. The optical element 20 is used to display a three-dimensional display object. The optical element 20 exerts an optical effect on the incident light. The optical effect is, for example, reflection or refraction. A three-dimensional display object is displayed at a position away from the optical element 20 by the light incident on the optical element 20. The display object is displayed, for example, at a distance of 1 mm to 10 mm from the optical element 20. The display object is observed three-dimensionally even when the observation angle is changed. By changing the position of the light source that emits the light that is incident on the optical element 20, the brightly observed part of the display object can be changed. The display object can be observed more three-dimensionally. The maximum dimension of the display object is, for example, 1 cm to 10 cm.

Below, we will explain each example of the optical element 20 shown in Figures 1, 3 to 7. The same reference numerals will be used for corresponding parts in each example, and duplicate explanations will be omitted.

<First Example of Optical Element>
A first example of the optical element 20 shown in Fig. 1 will be described. In the first example, the optical element 20 has a base material 21, a prism 30, a reflective layer 23, and a scattering layer 25, in this order. The optical element 20 can display a three-dimensional display object according to the shape of the prism 30 by reflecting light by the reflective layer 23. The scattering layer 25 may be separated from the reflective layer 23 or may be in contact with the reflective layer 23.

In the first example, the optical element 20 displays a three-dimensional object near the prism 30 relative to the substrate 21 using light incident near the prism 30 relative to the substrate 21.

The substrate 21 supports the prism 30 and the reflective layer 23. The substrate 21 may be transparent or opaque. The thickness of the substrate 21 is, for example, 10 μm or more and 10 mm or less. The substrate 21 may be produced by injection molding such as insert molding and in-mold molding. The material of the substrate 21 is, for example, polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polypropylene (PP), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), acrylonitrile ethylene-propylene-diene styrene (AES), or acrylonitrile styrene acrylate (ASA).

"Transparent" means that the visible light transmittance is 40% or more, preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. Visible light transmittance is specified as the average value of the total light transmittance at each wavelength when measured in 1 nm increments within the measurement wavelength range of 380 nm to 780 nm using a spectrophotometer (Shimadzu Corporation's "UV-3600i Plus", compliant with JIS K0115). The angle of incidence when measuring visible light transmittance is set to 0° unless a particular transmission direction is specified. The angle of incidence is the angle between the normal to the incident surface and the traveling direction of the incident light, and is less than 90°.

Not limited to the illustrated example, the substrate 21 may be omitted. For example, the substrate 21 may be formed as a substrate for a transfer foil, and after the optical element 20 is created, the substrate 21 may be peeled off by a peeling layer (not shown) provided between the substrate 21 and the prism 30.

The prism 30 forms a shape that exerts an optical effect. The prism 30 may be transparent or opaque. The prism 30 includes a bottom surface 31, a plurality of lens surfaces 32, and a plurality of rise surfaces 33. The lens surfaces 32 are a part of the surfaces that constitute the prism 30, and are formed to achieve an appropriate optical effect in the prism 30. In the illustrated example, the bottom surface 31 is in contact with the substrate 21, and is the same plane over the entire prism 30. In the first example, the lens surfaces 32 are formed by curved surfaces. Each lens surface 32 has a shape corresponding to the surface shape of the display object to be displayed. The entire lens surface 32 of the prism 30 has a shape corresponding to the entire surface shape of the display object to be displayed. The lens surfaces 32 are inclined with respect to the bottom surface 31. The rise surfaces 33 connect between adjacent lens surfaces 32 or between the bottom surface 31 and the lens surface 32. The rise surfaces 33 extend perpendicular to the bottom surface 31.

The height of the prism 30, in other words the length that the rise surface 33 extends from the bottom surface 31, is, for example, 2 μm or more and 5 μm or less. The length of each lens surface 32 in a plan view, in other words the length of each lens surface 32 along the bottom surface 31, is, for example, 3 μm or more and 200 μm or less. Because the height of the prism 30 is sufficiently large, light diffracted between the lens surfaces 32 is difficult to observe. Display objects can be displayed clearly.

In the example shown in FIG. 1, the lens surface 32 is configured as a curved surface. This allows the displayed object, which is displayed by light that has been optically affected according to the shape of the lens surface 32, to be displayed in a rounded shape that is close to the actual object.

The material of the prism 30 is, for example, a thermoplastic resin such as acrylic, acrylonitrile, or vinyl resin such as polyvinyl chloride, an ultraviolet curing resin, or an ionizing radiation curing resin.

The reflective layer 23 reflects light directed toward the lens surface 32. The reflective layer 23 is provided so as to cover the lens surface 32 of the prism 30. The reflective layer 23 may be provided so as to cover the bottom surface 31 of the prism 30 as well, or may be provided so as to cover the rise surface 33. The reflective layer 23 has a surface shape similar to that of the lens surface 32 in the portion covering the lens surface 32. The reflective layer 23 has a shape corresponding to the surface shape of the display object to be displayed. The thickness of the reflective layer 23 is, for example, 0.01 μm or more and 20 μm or less. The reflective layer 23 is, for example, a reflective layer made of a metal film, or a reflective layer made of a refractive index difference with the prism 30. The material of the reflective layer 23 is, for example, a metal such as aluminum, or a dielectric such as ZnS. The reflective layer 23 can be formed by evaporating a metal or a dielectric onto the lens surface 32 of the prism 30.

The scattering layer 25 diffuses the light that passes through it. In the example shown in FIG. 1, the scattering layer 25 is provided so as to cover the prism 30 whose lens surface 32 is covered by the reflective layer 23. The scattering layer 25 contains, for example, a binder resin and light diffusing particles dispersed in the binder resin. The binder resin is a resin such as a urethane resin, an acrylic polyol resin, an acrylic resin, an ester resin, an amide resin, a butyral resin, a styrene resin, a urethane-acrylic copolymer, a vinyl chloride-vinyl acetate copolymer resin, a vinyl chloride-vinyl acetate-acrylic copolymer resin, a chlorinated propylene resin, a nitrocellulose resin, or a cellulose acetate resin. The light diffusing particles are, for example, a white pigment such as titanium oxide or a transparent resin with a refractive index different from that of the binder resin. Alternatively, the scattering layer 25 may be a layer made of a transparent resin or the like having an uneven surface.

The light scattering properties of the scattering layer 25 are non-uniform. In other words, the light scattering properties are different at least in two places of the scattering layer 25. In further other words, there is a distribution in the scattering properties of the scattering layer 25. For example, the light scattering properties of the scattering layer 25 change in accordance with the displayed object displayed by the optical element 20. As a specific example, the light scattering properties of the scattering layer 25 are weakened at positions corresponding to the parts of the displayed object that are observed to stand out in front of the observer, and the light scattering properties of the scattering layer 25 are strengthened at positions corresponding to the parts of the displayed object that are observed to be recessed from the observer. This makes it easier to view the displayed object in a three-dimensional manner.

The scattering layer 25 may be omitted. Instead of the scattering layer 25, or in combination with the scattering layer 25, the lens surface 32 may be provided with an uneven shape 35 as shown in FIG. 2. The height of the uneven shape 35 is, for example, 0.1 μm or more and 2 μm or less. By providing the uneven shape 35 on the lens surface 32, the reflective layer 23 is also provided with an uneven shape. Due to the uneven shape provided on the reflective layer 23, the reflective layer 23 reflects light while scattering it. The uneven shape 35 provided on the lens surface 32 may be non-uniform among the multiple lens surfaces 32. In other words, the shapes of the uneven shape 35 provided on at least two lens surfaces 32 may be different from each other. In other words, there is a distribution in the scattering property due to the uneven shape 35. As a result, the uneven shape provided on the reflective layer 23 becomes non-uniform, and the light scattering property of the light reflected by the reflective layer 23 also becomes non-uniform.

<Second Example of Optical Element>
A second example of the optical element 20 shown in Fig. 3 will be described. In the second example, the optical element 20 has a base material 21, a prism 30, a reflective layer 23, and a scattering layer 25 in this order, similar to the first example.

In the second example, the shape of the lens surface 32 of the prism 30 is different from that in the first example. In the second example, the lens surface 32 of the prism 30 is composed of a single plane or a combination of planes. The reflective layer 23 provided to cover the lens surface 32 is also composed of a single plane or a combination of planes. This makes it easier to display an object displayed by light that has been optically affected in accordance with the shape of the lens surface 32 in a so-called polygonal shape, as if planes were glued together.

<Third Example of Optical Element>
A third example of the optical element 20 shown in Fig. 4 will be described. In the third example, the optical element 20 has a scattering layer 25, a substrate 21, and a prism 30 in this order. The optical element 20 refracts light by the prism 30, thereby displaying a three-dimensional display object according to the shape of the prism 30. The scattering layer 25 may be separated from the substrate 21 or may be in contact with the substrate 21. The substrate 21 and the prism 30 are transparent.

In the third example, the optical element 20 uses light incident from a position closer to the substrate 21 than the prism 30 to display a three-dimensional object closer to the prism 30 than the substrate 21.

As in the first example, the scattering layer 25 may be omitted. In the third example, instead of or in addition to the scattering layer 25, or in accordance with the provision of an uneven shape on the lens surface 32, the substrate 21 or the prism 30 may contain scattering matter. The scattering matter may be, for example, particles or fibers contained in the substrate 21 or the prism 30, or a crystal structure or a refractive index modulation structure in the substrate 21 or the prism 30. For example, in the case of particles, specifically, dielectrics such as silica or titanium oxide or metals such as silver particles may be used. The scattering matter diffuses light passing through the substrate 21 or the prism 30. The scattering matter is distributed non-uniformly in the substrate 21 or the prism 30. The non-uniform distribution of the scattering matter causes the light scattering properties of the substrate 21 or the prism 30 containing the scattering matter to be non-uniform.

<Fourth Example of Optical Element>
A fourth example of the optical element 20 shown in Fig. 5 will be described. In the fourth example, the optical element 20 has a base material 21, a prism 30, a reflective layer 23, and a light modulation layer 27 in this order. The optical element 20 can display a three-dimensional display object whose color and transparency may vary depending on the position by transmitting light reflected by the reflective layer 23 to the light modulation layer 27. The light modulation layer 27 may be separated from the reflective layer 23 or may be in contact with the reflective layer 23.

The light modulation layer 27 modulates the light passing through it. For example, the color or transmittance of the light passing through the light modulation layer 27 changes. The light modulation layer 27 absorbs a portion of the light for each wavelength in the visible light range, or for the entire visible light range. This allows the light modulation layer 27 to change the color or transmittance of the light passing through it. The light modulation layer 27 may have a non-uniform color or transmittance. In other words, at least two locations in the light modulation layer 27 may have different colors or transmittances. For example, each portion of the display object displayed by the optical element 20 may be colored or made translucent. In the illustrated example, the color is different between the first position 27A and the second position 27B of the light modulation layer 27.

In the light modulation layer 27, non-uniform color means that at least one of the brightness, saturation, and hue of the color is non-uniform.

The light modulation layer 27 is a thin-film member. The light modulation layer 27 is provided, for example, by printing ink on paper. The printed ink is a different color at each position, so that the light modulation layer 27 can modulate the light passing through it. The thickness of the light modulation layer 27 is, for example, 5 μm or more and 50 μm or less.

<Fifth Example of Optical Element>
A fifth example of the optical element 20 shown in Fig. 6 will be described. In the fifth example, the optical element 20 has a base material 21, a light modulation layer 27, and a prism 30, in this order. The optical element 20 can display a three-dimensional display object whose color and transparency may vary depending on the position by refracting light transmitted through the base material 21 and the light modulation layer 27 at the prism 30. The base material 21 and the prism 30 are transparent.

Sixth Example of Optical Element
A sixth example of the optical element 20 shown in Fig. 7 will be described. In the sixth example, the optical element 20 has a light modulation layer 27, a substrate 21, and a prism 30, in this order. The optical element 20 can display a three-dimensional display object whose color and transparency may vary depending on the position by refracting light transmitted through the light modulation layer 27 and the substrate 21 at the prism 30. The substrate 21 and the prism 30 are transparent.

Although the first to sixth examples of the optical element 20 have been described, it is also possible to combine the configurations of each example as appropriate. For example, the optical element 20 may have a substrate 21, a prism 30, a reflective layer 23, a scattering layer 25, and a light modulation layer 27.

FIG. 8 shows an enlarged example of a top view of the optical element 20. The optical element 20 shown in FIG. 8 can be any of the first to sixth examples of the optical element 20. FIG. 8 shows a prism 30 in the optical element 20. The multiple lens surfaces 32 included in the prism 30 are shown in shades according to their height from the bottom surface 31. In FIG. 8, the parts of the lens surfaces 32 that are in front of the paper surface are shown in light colors, and the parts that are behind the paper surface are shown in dark colors. At the boundary between the darkest and lightest parts, there is a rise surface 33 that extends toward the paper surface.

As shown in FIG. 8, the prism 30 includes a plurality of polygonal regions 37. The polygonal regions 37 partially include the lens surfaces 32. In a polygonal region 37, the lens surfaces 32 extend linearly in a first direction d1 and are arranged in a second direction d2. The second direction d2 may be non-parallel to the first direction d1 and perpendicular to the first direction d1. The lens surfaces 32 may be arranged at equal intervals in the second direction d2. In another polygonal region 37 adjacent to a polygonal region 37, the lens surfaces 32 extend linearly in a third direction d3 and are arranged in a fourth direction d4. The third direction d3 is a direction different from the first direction d1. The fourth direction d4 may be non-parallel to the third direction d3 and perpendicular to the third direction d3. From another perspective, the polygonal region 37 is determined by the direction in which the lens surfaces 32 extend. A collection of lens surfaces 32 arranged to extend in the same direction defines one polygonal area 37. In adjacent polygonal areas 37, the lens surfaces 32 extend in different directions. In adjacent polygonal areas 37, the lens surfaces 32 are connected. In other words, the lens surfaces 32 extend continuously while bending across multiple polygonal areas 37. The boundaries of the polygonal areas 37 are defined by the bent portions of the lens surfaces 32.

The shape of each polygonal area 37 may be any shape, such as a triangle, a rectangle, or a pentagon. Triangles are particularly desirable because they can be connected without inconsistencies between multiple polygonal areas and are widely used as CAD data. The shapes of each polygonal area 37 may be different from each other. The area of one polygonal area 37 is, for example, 10 μm ² or more and 25,000,000 μm ² or less. The number of lens surfaces 32 included in one polygonal area 37 is, for example, 3 or more and 100 or less.

In each polygonal area 37, multiple lens surfaces 32 extend in the same direction. An object is displayed when light is subjected to optical effects along the lens surfaces 32. The surface of the object is displayed in a polygonal shape corresponding to each polygonal area 37. Each polygonal area 37 forms a polygon of the three-dimensional object to be displayed.

When the change in appearance is clearly recognized when the position at which the displayed object is observed is changed, the displayed object can be observed more three-dimensionally. FIG. 9 is a diagram for explaining the difference in appearance of the displayed object when the position at which the displayed object is observed is changed. As shown in FIG. 9, it is assumed that the displayed object is observed from a position about the clear vision distance L [mm] away from the optical element 20. When the position at which the displayed object is observed is changed, it is assumed that the observation position is changed by about the interpupillary distance D [mm]. When the polygon observed to emit strong light when the observation position is changed, the change in appearance is clearly recognized. From the above, when observing from a position about the clear vision distance L [mm] away, when the observation position is changed by about the interpupillary distance D [mm], if the polygon observed to emit strong light changes, the change in appearance is clearly recognized. The angle between the normal direction ndA of the lens surface 32 of the first polygonal area 37A that forms a polygon observed to emit strong light at the first position PA and the normal direction ndB of the lens surface 32 of the second polygonal area 37B that forms a polygon observed to emit strong light at the second position PB is defined as θ [rad]. In this case, the above-mentioned condition is formulated as the following relationship (i).
2×θ×L≧D/2 (i)

In general, the clear vision distance L is 250 mm, and the interpupillary distance D is 65 mm. From the relationship (i), the range of θ is as shown in the following relationship (ii).
θ≧0.065rad≒3.7° (ii)

The greater the proportion of polygonal regions 37 that satisfy relationship (ii), the greater the change in appearance when the position from which the displayed object is observed is changed, and the more three-dimensional the displayed object appears. Specifically, if the sum of the areas of the lens surfaces 32 in the polygonal regions 37 that satisfy relationship (ii) is 10% or more, and preferably 20% or more, of the area of the entire prism 30, in other words, the sum of the areas of the lens surfaces 32, the more three-dimensional the displayed object appears.

Not limited to the example shown in FIG. 8, the prism 30 does not have to include the polygonal area 37. The lens surface 32 may extend in a curved shape when viewed from above.

The optical element 20 described above may be included in the light guide plate 10. An example of a light guide plate 10 including an optical element 20 is shown in Figs. 10 to 12. The light guide plate 10 is generally configured as a rectangular parallelepiped member having a pair of main surfaces with the sides in the thickness direction being relatively smaller than the other sides, and the side surface defined between the pair of main surfaces includes four faces. The thickness of the light guide plate 10, in other words the length between the pair of main surfaces of the light guide plate 10, is, for example, 100 μm or more and 5 cm or less.

The light guide plate 10 has the above-mentioned light exit surface 11 formed by one of the main surfaces, a back surface 12 formed by the other main surface opposite the light exit surface 11, and a side surface extending between the light exit surface 11 and the back surface 12. One of the side surfaces forms the light entrance surface 13. A light source 5 is provided facing the light entrance surface 13. Light entering the light guide plate 10 from the light entrance surface 13 travels inside the light guide plate 10 towards the opposite surface 14 opposite the light entrance surface 13.

<First Example of Light Guide Plate>
In a first example of the light guide plate 10 shown in Fig. 10, the optical element 20 is disposed inside the light guide plate 10. In the first example, light from the light source 5 travels inside the light guide plate 10 while being reflected by the light exit surface 11 and the back surface 12 of the light guide plate 10. When the light enters the prism 30 of the optical element 20, it is optically acted on along the shape of the lens surface 32 of the prism 30. As a result, the light enters the light exit surface 11 at an angle less than the critical angle for total reflection and exits from the light exit surface 11. The exiting light displays a three-dimensional display object due to the shape of the lens surface 32.

<Second Example of Light Guide Plate>
In the second example of the light guide plate 10 shown in FIG. 11, the prism 30 of the optical element 20 is integrated with the light guide plate 10. In the optical element 20, the substrate 21 is omitted. The lens surface 32 of the prism 30 is integrated with the rear surface 12 of the light guide plate 10. Not limited to the illustrated example, the lens surface 32 may be integrated with the light output surface 11 of the light guide plate 10. In the second example, the light from the light source 5 travels inside the light guide plate 10 while being reflected by the light output surface 11 and the rear surface 12 of the light guide plate 10. When the light is incident on the lens surface 32 on the front surface of the light guide plate 10, the light is subjected to an optical action along the shape of the lens surface 32 of the prism 30. As a result, the light is incident on the light output surface 11 at an angle less than the critical angle of total reflection and is output from the light output surface 11. The output light displays a three-dimensional display object due to the shape of the lens surface 32.

<Third Example of Light Guide Plate>
In the third example of the light guide plate 10 shown in FIG. 12, the prism 30 of the optical element 20 is integrated with the light guide plate 10. In FIG. 12, three light guide plates 10 are shown, namely, a first light guide plate 10A, a second light guide plate 10B, and a third light guide plate 10C. A first light source 5A is arranged facing the light entrance surface of the first light guide plate 10A. A second light source 5B is arranged facing the light entrance surface of the second light guide plate 10B. A third light source 5C is arranged facing the light entrance surface of the third light guide plate 10C. The lights emitted by the first light source 5A, the second light source 5B, and the third light source 5C may be different colors. For example, the first light source 5A emits red light, the second light source 5B emits green light, and the third light source 5C emits blue light. Each light guide plate has a configuration similar to that of the light guide plate of the second example. As in the second example, the light from the first light source 5A travels inside the first light guide plate 10A while being reflected by the light exiting surface and the back surface of the first light guide plate 10A, and is optically acted on along the shape of the first lens surface 32A of the first prism 30A. The light from the second light source 5B travels inside the second light guide plate 10B while being reflected by the light exiting surface and the back surface of the second light guide plate 10B, and is optically acted on along the shape of the second lens surface 32B of the second prism 30B. The light from the third light source 5C travels inside the third light guide plate 10C while being reflected by the light exiting surface and the back surface of the third light guide plate 10C, and is optically acted on along the shape of the third lens surface 32C of the third prism 30C. The light that has been optically acted on along the shape of the lens surface of the prism is incident on the light exiting surface at less than the total reflection critical angle and is emitted from the light exiting surface. The emitted light displays a three-dimensional display object due to the shape of the lens surface. In the plan view of the first light guide plate 10A, the second light guide plate 10B, and the third light guide plate 10C, the positions where the lens surfaces are provided do not overlap each other, but are shifted. The light from each light guide plate 10 is unlikely to be optically affected by the other light guide plates. This allows a three-dimensional display object to be displayed by light of multiple colors. Alternatively, in the plan view of the first light guide plate 10A, the second light guide plate 10B, and the third light guide plate 10C, some of the positions where the lens surfaces are provided may overlap each other. This allows a three-dimensional display object to be displayed by light in which multiple colors are mixed. For example, a full-color three-dimensional display object can be displayed.

An example of a method for manufacturing the optical element 20 will be described.

Data for the object to be displayed using the optical element 20 is prepared. Figure 13 shows data for the shape of a pot as an example of data for the object to be displayed. The data for the object to be displayed is three-dimensional. In other words, the data for the object to be displayed includes not only planar information but also height information. The data for the object to be displayed is created using CAD (Computer Aided Design).

Data on the shape of the lens surface to be created is created from the data on the display object. To prevent the formation of steep slopes on the lens surface, the height information of the data on the display object is compressed. This makes it easy to form the lens surface. The height information of the data on the display object is, for example, 1/3. The data on the display object is divided into fixed heights to form strip data. The height information of the strip data is, for example, 2 μm to 5 μm. In the part where the display object is displayed in three dimensions, in other words, the part containing the height information of the strip data, the height information of the uneven shape is added to the height information of the strip data. The height of the uneven shape information is, for example, 0.1 μm to 2 μm. The strip data information to which the uneven shape information has been added is gradated. Specifically, of the strip data information to which the uneven shape information has been added, the lowest height information is set to 0, and the highest height information is set to 255. The distance between the lowest and highest height information is divided by 255, and the numerical values between the lowest and highest height information are determined. The strip data is gradated by these numerical values.

A prism master is created on a glass substrate based on the gradational band data. A resist is applied onto the glass substrate. The resist is exposed by irradiating it with a laser. The intensity of the irradiated laser is changed based on the gradational band data. For example, the higher the numerical value of the gradational band data, the stronger the exposure intensity is. In this way, a first prism master is created with a shape based on the gradational band data. The shape of the first prism master is based on the data of the display object. A second master is created by, for example, plating the first prism master with nickel and then peeling it off.

The shape of the second prism original plate is replicated on the UV-curable resin placed on the substrate. For example, the second prism original plate is pressed against the UV-curable resin before hardening that is placed on the substrate. The UV-curable resin takes on a shape that reflects the shape of the second prism original plate. The UV-curable resin is hardened by irradiating it with UV rays. The hardened UV-curable resin becomes a prism. Lens surfaces and rise surfaces are formed according to the shape of the prism original plate. A prism is created on the substrate.

Metal is evaporated so as to cover the lens surface. The evaporated metal is, for example, aluminum. The evaporated metal has a thickness of, for example, 0.01 μm or more and 20 μm or less. The evaporated metal forms a reflective layer.

The above steps allow the first example of optical element 20 to be manufactured.

After creating a prism on the substrate, a light modulation layer created by printing ink on paper based on the data of the display object may be aligned with the lens surface. This allows the fourth to sixth examples of the optical element 20 to be manufactured.

FIG. 14 is a simulation of an example of an object that is assumed to be displayed using a conventional optical element. In the optical element that displays the object shown in FIG. 14, the base material and prism do not contain any scattering material, the lens surface is not provided with an uneven shape, and the optical element does not have a scattering layer. Light is irradiated from a direction that forms an angle of 15° with respect to the front direction of the optical element.

When light is irradiated onto an optical element and is subjected to an optical effect on the lens surface, it is possible to display a three-dimensional object. The object is observed from the front, in other words, from the normal direction of the optical element. In the optical element that displays the object shown in the example of Figure 14, the light irradiated onto the optical element is not scattered sufficiently, which reduces the design quality of the object.

FIG. 15 is a simulation of an example of an object that is assumed to be displayed using the optical element 20 of this embodiment. In the optical element 20 of this embodiment that displays the object shown in FIG. 15, the base material 21 and the prism 30 contain scattering material, and/or the lens surface 32 is provided with an uneven shape, and/or the optical element 20 has a scattering layer 25. As with the example shown in FIG. 14, light is irradiated from a direction that forms an angle of 15° with respect to the front direction.

The light irradiated to the optical element 20 is subjected to an optical effect at the lens surface 32, thereby displaying a three-dimensional display object. The display object is observed from the front direction, in other words, from the normal direction of the optical element 20. Since the optical element 20 contains a scattering element, the light irradiated to the optical element 20 is sufficiently scattered. As can be seen from a comparison of Figures 14 and 15, scattering the light with the optical element 20 can improve the design of a three-dimensional display object displayed using the optical element 20. With the light being sufficiently scattered, the display object can be easily observed from different angles.

FIG. 16 is an example of a three-dimensional display object that was actually observed using the optical element 20 of this embodiment. The display object shown in FIG. 16 is displayed by illuminating the optical element 20 with light from indoor lighting, rather than a light source in a specific direction. As shown in FIG. 16, by using the optical element 20 of this embodiment, a three-dimensional display object with a highly aesthetic design can be displayed.

When the lens surface 32 has an uneven shape 35, the uneven shape 35 is non-uniform among the multiple lens surfaces 32. The light scattering properties of the uneven shape 35 can be changed to match the displayed object displayed using the optical element 20. This can further improve the design of the displayed object.

If the substrate 21 or the prism 30 contains scattering matter, the scattering matter is distributed non-uniformly in the substrate 21 or the prism 30. The light scattering properties of the scattering matter can be changed to match the displayed object displayed using the optical element 20. This can further improve the design of the displayed object.

When the optical element 20 has a scattering layer 25, the scattering properties of the scattering layer 25 are non-uniform. The light scattering properties of the scattering layer 25 can be changed to match the displayed object that is displayed using the optical element 20. This can further improve the design of the displayed object.

The prism 30 includes a polygonal area 37. The surface of the displayed object is displayed in a polygonal shape corresponding to the polygonal area 37. The displayed object is displayed in a polygonal shape. This can further improve the design of the displayed object. Furthermore, the shape of the lens surface 32 of the prism 30 can be calculated by a simple calculation, which makes it easier to create data on the shape of the lens surface 32. The manufacturing costs of the optical element 20 can be reduced.

The lens surfaces 32 of adjacent polygonal regions 37 are connected. Since there is no step between the lens surfaces 32 of adjacent polygonal regions 37, no unnecessary diffraction occurs, and the displayed object can be clearly observed. This prevents deterioration of the design of the displayed object.

The sum of the areas of the lens surfaces 32 in polygonal sections 37 in which the normal direction of the lens surface 32 forms an angle of 3.7° or more with the normal direction of the lens surface 32 of any adjacent polygonal section 37 is 10% or more of the sum of the areas of the lens surfaces 32 of the entire prism 30. Polygonal sections 37 in which the normal direction forms an angle of 3.7° or more with the normal direction of any adjacent polygonal section 37 correspond to parts of a displayed object where the change in appearance becomes clear when the observation position is changed. By having a sufficient number of such polygonal sections 37, the change in appearance becomes clear when the observation position of the displayed object is changed, and the displayed object can be observed in a more three-dimensional manner. The design of the displayed object can be further improved.

The optical element 20 has a light modulation layer 27 that is non-uniform in color or transmittance. The color and transmittance of the light modulation layer 27 can be changed to match the object displayed using the optical element 20. This can further improve the design of the displayed object.

The optical element 20 has a reflective layer 23 that is provided to cover the lens surface 32. By reflecting light at the reflective layer 23, an object can be displayed in the same direction as the light is incident on the optical element 20.

The optical element 20 of this embodiment is used to display a three-dimensional object. The optical element 20 includes a prism 30 including a bottom surface 31 and a plurality of lens surfaces 32 inclined relative to the bottom surface 31. The lens surfaces 32 are provided with an uneven shape 35. Alternatively, the prism 30 includes scattering material. Alternatively, the prism 30 further includes a scattering layer 25 superimposed on the prism 30. Alternatively, the prism 30 further includes a light modulation layer 27 with non-uniform color or transmittance. According to the optical element 20 of this embodiment, the design of the displayed object can be improved by scattering light or adjusting the color or transmittance depending on the position.

Various modifications can be made to the above-described embodiment.

For example, in the above-described embodiment, the reflective layer 23 may be changed to a partially reflective layer. The partially reflective layer reflects a part of the incident light and transmits the other part. The reflectance of the partially reflective layer is, for example, 10% to 90%, and preferably 30% to 70%, and the transmittance of the partially reflective layer is, for example, 10% to 90%, and preferably 30% to 70%. The partially reflective layer can be produced, for example, by thinning the film thickness of the metal evaporated onto the lens surface 32. The partially reflective layer allows light to pass through the displayed object while displaying the displayed object. The displayed object is observed to be made of a transparent material such as glass. The design of the displayed object can be improved.

In the above-described embodiment, the lens surfaces 32 of the prisms 30 may be arranged along a certain closed curve as shown in FIG. 17 when observed from above. An optical element 20 having such lens surfaces 32 can display an object such as an infinite staircase, with upward or downward loops. The optical element 20 can display an object with a highly aesthetic design.

5 Light source 10 Light guide plate 20 Optical element 21 Substrate 23 Reflective layer 25 Scattering layer 27 Light modulation layer 30 Prism 31 Bottom surface 32 Lens surface 33 Rise surface 35 Concave and convex shape 37 Polygonal area

Claims

An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
The optical element has an uneven surface on the lens surface.
The optical element of claim 1, wherein the uneven shape is non-uniform among the lens surfaces.
An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
The prism is an optical element including a scatterer.
The optical element of claim 3, wherein the scattering matter is distributed non-uniformly.
An optical element used to display a three-dimensional display object,
a prism including a base surface and a plurality of lens surfaces inclined relative to the base surface;
a scattering layer overlying the prism.
The optical element of claim 5, wherein the light scattering properties of the scattering layer are non-uniform.
An optical element used to display a three-dimensional display object,
A prism including a base surface and a plurality of lens surfaces inclined with respect to the base surface,
the prism includes a plurality of polygonal sections;
An optical element, wherein in a given polygonal region, the lens surfaces extend linearly in a first direction and are arranged in a second direction non-parallel to the first direction.
The optical element of claim 7, wherein the lens surfaces are connected in adjacent polygonal regions.
The optical element of claim 8, wherein the sum of the areas of the lens surfaces in the polygonal regions in which the normal direction of the lens surfaces forms an angle of 3.7° or more with the normal direction of the lens surfaces of any of the adjacent polygonal regions is 10% or more of the sum of the areas of the lens surfaces of the entire prism.
The optical element according to claim 1, 3, 5 or 7, further comprising a light modulating layer having a non-uniform color or transmittance.
An optical element used to display a three-dimensional display object,
a prism including a base surface and a plurality of lens surfaces inclined relative to the base surface;
a light modulating layer overlying the prism;
An optical element, wherein the light modulating layer is non-uniform in color or transmittance.
The optical element according to claim 1, 5, 7 or 11, further comprising a reflective layer or a partially reflective layer provided to cover the lens surface.
The optical element according to claim 1, 3, 5, 7 or 11, wherein the lens surfaces are arranged along a closed curve.
A light guide plate including the optical element according to claim 1, 3, 5, 7 or 11.