Display device

Abstract

To provide a display device whose structure can be simplified, and with which it is possible to show various display patterns on a transparent display board.SOLUTION: A display device (1f) comprises: a plurality of light sources (10m) including a light source that emits light of a first wavelength; a display unit that includes, on the front and / or back plane of a single display board (20), a first display pattern (30c) that corresponds to light of the first wavelength and a second display pattern (30d) that does not correspond to light of the first wavelength; and a turn-on control circuit that switches a light source between the plurality of light sources that is to be turned on, and thereby switches each of the plurality of display patterns (30c, 30d) to be displayed and hidden independently of each other. The wavelength range of light that is scattered in the first display pattern (30c) when light of the first wavelength has entered the first display pattern (30c) overlaps at least partly the wavelength range of light that is scattered by the first display pattern (30c) when white light has entered the display board (20).SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] A display device has been proposed that has a display unit in which display panels that display patterns such as pictures, letters, or symbols that are illuminated by light entering from the side are stacked and a plurality of stacked display panels are arranged (see, for example, Patent Document 1). Stacking is also called multi-layering. This display device is capable of displaying a plurality of display patterns on a transparent display unit by arranging a plurality of stacked display panels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-211498 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional display devices, each independent display panel can only display one type of display pattern, which means that the variety of display patterns that the display device can display is insufficient.Furthermore, in order to increase the number of display patterns, it is necessary to use stacked display panels, which results in a complex structure.

[0005] An object of the present disclosure is to provide a display device that can simplify its configuration and that can display a variety of display patterns on a transparent display panel. [Means for solving the problem]

[0006] The display device of the present disclosure displays a display object. outfit Place Anda display unit that has a plurality of light sources that respectively emit light of different wavelengths and a transparent display plate, and that has a plurality of display patterns, each having a peak wavelength of scattered light that is different from one another, on at least one of the front and back surfaces of a single display plate to display the display target in response to the light emitted by the light sources, and that puts the display pattern in a visible display state when the light source emits light that is scattered by the display pattern, and puts the display pattern in a transparent non-display state when the light source does not emit light that is scattered by the display pattern; and a lighting control circuit that controls the plurality of light sources to switch the wavelength of light that enters the single display plate by switching which light source to be turned on, thereby independently switching between display and non-display of each of the plurality of display patterns, wherein the plurality of light sources include a light source that emits light of a first wavelength from the light of different wavelengths, and the plurality of display patterns are formed by transparent ink containing a plurality of types of light scattering particles that scatter light that is different from one another, and the light of the first wavelength is scattered more significantly by the first display pattern than by the second display pattern. The display pattern has a plurality of divided minute regions, and the wavelengths of light scattered in adjacent regions of the plurality of regions are different. It is characterized by: [Effects of the Invention]

[0007] According to the display device of the present disclosure, it is possible to simplify the configuration and display a variety of display patterns on a transparent display panel. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating a configuration of a display device according to an embodiment. [Figure 2] FIG. 2 is a perspective view schematically illustrating the configuration of the display device shown in FIG. [Figure 3] 2 is a side view showing a display pattern of the display device shown in FIG. 1 and light traveling inside a display panel. FIG. [Figure 4] FIG. 10 is a front view schematically showing another example of a display pattern of the display device according to the embodiment. [Figure 5]1 is a side view showing a display pattern of a display device according to an embodiment and light traveling inside a display panel. [Figure 6] 1(a) and 1(b) are a front view and a side view schematically showing the configuration of a display device according to a first embodiment. [Figure 7] 1(a) and 1(b) are a front view and a side view schematically showing the configuration of a display device according to a first modification of the first embodiment. [Figure 8] 10(a) and 10(b) are a front view and a side view schematically showing the configuration of a display device according to a second modification of the first embodiment. [Figure 9] 10(a) and 10(b) are a front view and a side view schematically showing the configuration of a display device according to a third modification of the first embodiment. [Figure 10] 10(a) and 10(b) are a front view and a side view schematically showing the configuration of a display device according to a fourth modification of the first embodiment. [Figure 11] 10(a) and 10(b) are a front view and a side view schematically showing the configuration of a display device according to a fifth modification of the first embodiment. [Figure 12] 10(a) and 10(b) are front views schematically illustrating the configuration of a display device according to a sixth modification of the first embodiment. [Figure 13] 13 is a front view including a partially enlarged view showing a display device according to a sixth modification of the first embodiment. FIG. [Figure 14] 13A and 13B are diagrams showing examples of decoration of each display pattern according to Modification 6 of Embodiment 1. [Figure 15] FIG. 13 is a diagram showing an example of decoration of a plurality of display patterns according to a sixth modification of the first embodiment. [Figure 16] 13 is a front view including another example of an enlarged partial view showing the display device according to the sixth modification of the first embodiment. FIG. [Figure 17] 13(a) and 13(b) are front views schematically illustrating the configuration of a display device according to a seventh modification of the first embodiment. [Figure 18] 13(a), 13(b), 13(c), and 13(d) are perspective views schematically illustrating the configuration of a display device according to an eighth modification of the first embodiment. [Figure 19]10(a) and 10(b) are a front view and a side view schematically showing the configuration of a display device according to a second embodiment. [Figure 20] 10(a) and 10(b) are a side view and a perspective view schematically showing the configuration of a display device according to a third embodiment. [Figure 21] 10 is a side view showing the structure of a light distribution control element and a display panel of a display device according to Embodiment 3, and light rays. FIG. [Figure 22] 10 is a side view showing the structure of a light distribution control element and a display panel of a display device according to Embodiment 3, and light rays. FIG. [Figure 23] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a first modification of the third embodiment, and light rays. FIG. [Figure 24] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a second modification of the third embodiment, and light rays. FIG. [Figure 25] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a second modification of the third embodiment, and light rays. FIG. [Figure 26] 10(a) and 10(b) are a side view and a perspective view showing the structure of a light distribution control element and a display panel of a display device according to a third modification of the third embodiment, and light rays. [Figure 27] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a third modification of the third embodiment, and light rays. FIG. [Figure 28] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a third modification of the third embodiment, and light rays. FIG. [Figure 29] 13 is a side view schematically showing the configuration of a light distribution control element and a display panel of a display device according to a fourth modification of the third embodiment. FIG. [Figure 30] 10(a) and 10(b) are a side view and a perspective view showing the structure of a light distribution control element and a display panel of a display device according to a fifth modification of the third embodiment. [Figure 31] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a fifth modification of the third embodiment, and light rays. FIG. [Figure 32]13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a fifth modification of the third embodiment, and light rays. FIG. [Figure 33] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a fifth modification of the third embodiment, and light rays. FIG. [Figure 34] 13(a) and 13(b) are a side view and a perspective view showing the structure of a light distribution control element and a display panel of a display device according to a sixth modification of the third embodiment. [Figure 35] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a sixth modification of the third embodiment, and light rays. FIG. [Figure 36] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a sixth modification of the third embodiment, and light rays. FIG. [Figure 37] 13 is a side view showing the structure of a light distribution control element and a display panel of a display device according to a sixth modification of the third embodiment, and light rays. FIG. [Figure 38] 13A and 13B are a side view and a perspective view of a light distribution control element and a display panel of a display device according to a sixth modification of the third embodiment. [Figure 39] FIG. 10(a) is a perspective view showing a part of the configuration of a display device according to a fourth embodiment, and FIG. 10(b) is a perspective view showing a schematic configuration of the display device according to the fourth embodiment. [Figure 40] FIG. 10 is a side view schematically showing the configuration of a display device according to a fifth embodiment. [Figure 41] FIG. 13 is a diagram schematically illustrating a configuration of a display device according to a sixth embodiment. [Figure 42] FIG. 22 is a diagram schematically illustrating a configuration of a display device according to a first modification of the sixth embodiment. [Figure 43] FIG. 22 is a diagram schematically illustrating a configuration of a display device according to a second modification of the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Display devices according to embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and the embodiments can be appropriately combined and modified.

[0010] The figure shows the coordinate axes of an XYZ Cartesian coordinate system. The X-axis and Y-axis are the coordinate axes in the horizontal and vertical directions (or the vertical and horizontal directions) of the human field of vision when viewing the display device. The Z-axis is the coordinate axis in the thickness direction of the display panel. In addition, in the figure, the same or similar components are given the same symbols.

[0011] Overview of the embodiment Fig. 1 is a diagram schematically showing the configuration of a display device 100 according to an embodiment. Fig. 2 is a perspective view schematically showing the configuration of the display device 100 shown in Fig. 1. Fig. 3 is a side view schematically showing the configuration of the display device 100 shown in Fig. 1.

[0012] The display device 100 includes a light source 10 and a display unit 40. The display unit 40 includes a transparent display panel 20 that guides light, and a display target. The display target is, for example, a display pattern 30 or a plurality of display patterns (for example, as shown in FIG. 6(a) described later) that are replaceably provided on the display panel 20. The light source 10 is a light source that emits directional light. The display panel 20 is a rectangular plate-like member having a front surface (i.e., front face) 201 as a first surface, a back surface (i.e., rear face) 202 as a second surface opposite the front surface 201, and four side surfaces 203 connecting the front surface and the rear surface. However, the shape of the display panel 20 is not limited to the shape shown in the figure. The first surface may be the rear surface, and the second surface may be the front surface.

[0013] When the lighting control circuit 90, which is a control device that controls the operation of the light source 10, turns on the light source 10, light L0 emitted from the light source 10 enters the interior of the display board 20, is guided, and exits the display board 20 via the display pattern 30, causing the display pattern 30 to be in a display state. In FIG. 3 , the light L0 is scattered by the display pattern 30 provided on the back surface 202 of the display board 20 and exits the display board 20 from the front surface 201 of the display board 20. However, the front surface 201 and the back surface 202 of the display board 20 may be reversed. The display state is a visible state in which a person can see the display pattern 30. The non-display state is a state in which the light source 10 is not turned on, and the display pattern 30 is not or barely visible to a person. In the non-display state, the display unit 40 is transparent.

[0014] The light source 10 includes, for example, one or more light-emitting elements. The multiple light-emitting elements may be arranged one-dimensionally in the X-axis direction, for example. The light-emitting element is, for example, a solid-state light source. The solid-state light source is a directional light source. The solid-state light source is, for example, a semiconductor light source. The light-emitting element is, for example, a light-emitting diode (LED). The solid-state light source may be an organic electroluminescence light source or a laser diode. The solid-state light source may also have a structure that emits light by irradiating excitation light onto a phosphor coated on a flat surface. The light source may be any of a white light source that emits white light, a full-color light source that emits light of red (R), green (G), and blue (B), and a monochromatic light source.

[0015] The display unit 40 includes, for example, a single display panel 20 and a display pattern 30. The display panel 20 is a member filled with a refractive material. The display panel 20 may be stacked, or multiple display panels 40 may be arranged horizontally, vertically, or both when viewed from the front. Stacking is also referred to as multi-layering. The display panel 20 is a transparent member. In this application, "transparent" refers to the property of allowing light to pass through, including being substantially transparent. The display panel 20 is made of a plastic such as acrylic. Examples of plastic that can be used include PMMA (polymethyl methacrylate) and PC (polycarbonate). The display panel 20 may also be made of glass. A display pattern 30 is provided on at least one of the front surface 201 and the back surface 202 of the display panel 20. The display pattern 30 may be a single-color or multi-color pattern.

[0016] The light source 10 is disposed opposite the side surface 203 of the display board 20. However, if a structure that allows light to enter the interior of the display board 20 (described in the third embodiment below) is adopted, the position of the light source 10 is not limited to the position shown in the figure. The light emitted from the light source 10 enters the side surface 203 of the display board 20 and is guided inside the display board 20.

[0017] When forming the display pattern 30 on the display board 20 (e.g., when decorating the display board 20), the display pattern 30 is printed by applying ink to at least one of an area on the front surface 201 of the display board 20 corresponding to the planned formation portion of the display pattern 30 (here, a rightward arrow mark) and an area on the back surface 202 of the display board 20 corresponding to the planned formation portion of the display pattern 30. The ink is, for example, a transparent ink. The transparent ink contains, for example, light-scattering particles. The printing method is, for example, silkscreen printing. When printing on the front surface 201 of the display board 20, the display pattern 30 is likely to be soiled or damaged, so it is preferable to print on the back surface 202 of the display board 20. Here, the front surface 201 of the display board 20 is the surface of the display board 20 that constitutes the display unit 40 and that faces a person observing the display unit 40.

[0018] The painted portions of the display pattern 30 are printed as a dot pattern, and the background is made transparent when the display pattern 30 is not lit, thereby increasing transparency.

[0019] The color density of the display pattern 30 may be adjusted by designing the dot diameter, pitch, or both. However, to increase the resolution, it is desirable to make the pitch as small as possible. To make the color darker, the dot area per unit area should be increased. To make the color lighter, the dot area per unit area should be decreased.

[0020] FIG. 4 is a front view schematically illustrating another configuration of the display pattern of the display device 101 according to the embodiment. FIG. 4 illustrates an example in which transparent ink is not applied to an area of ​​the front surface 201 or the back surface 202 of the display panel 20 of the display unit 40a corresponding to a planned formation area of ​​the display pattern 30a (here, a rightward arrow mark), and transparent ink is applied to an area other than this area (i.e., a peripheral area), which is a background area. Light guided inside the display panel 20 is scattered by light-scattering particles contained in the transparent ink. Some of the scattered light does not satisfy the total reflection condition at the boundary of the front surface 201 of the display panel 20 and is emitted to the outside through the front surface 201 of the display panel 20. The display pattern 30a is displayed according to the above principle. When the light source 10 is turned on, the viewer can view the display pattern 30a because the peripheral area of ​​the display pattern 30a emits light. When the light source 10 is turned off, the peripheral area of ​​the display pattern 30a cannot be viewed, and as a result, the display pattern 30a cannot be viewed.

[0021] Since transparent ink does not adhere well to glass, when transparent ink is used to form the display pattern 30a, it is preferable to use a plastic such as acrylic for the display plate 20.

[0022] Furthermore, if the light source 10 is a laser light source, speckles can be generated when the display pattern 30a is emitting light, which can further improve the visibility of the display pattern 30a.

[0023] As a method for decorating the display pattern on the display board 20, a method of applying prism processing to a portion of the back surface 202 of the display board 20 where the display pattern 30b is to be formed may be employed. FIG. 5 is a side view schematically showing the display pattern 30b of the display device 102 according to the embodiment. Light guided inside the display board 20 is reflected by an inclined portion (i.e., a prism-shaped portion) formed by prism processing on the back surface 202. A portion of the light reflected by the inclined portion does not satisfy the condition for total reflection at the front surface 201 of the display board 20 (i.e., the boundary with air) and is emitted to the outside through the front surface 201 of the display board 20. The display pattern 30b is in a display state according to this principle. The display pattern 30b is visible when the light source 10 is turned on, and is invisible when the light source 10 is turned off. Note that the number of elongated convex shapes in the X-axis direction formed by prism processing is not limited to the number shown in the figure. Furthermore, the shape of the processed display pattern 30b is not limited to a prism shape, and it may be other structures having a surface facing in a direction different from the surface on which the display pattern 30b is formed.

[0024] First Embodiment 6(a) and 6(b) are front and side views illustrating a schematic configuration of the display device 1 according to the first embodiment. The display unit 40c of the display device 1 includes two directional light sources 10c and 10d and two display patterns 30c and 30d provided on the display board 20 and configured to be independently display-controllable. The light sources 10c and 10d and the display patterns 30c and 30d are arranged in corresponding positions. Light L1 emitted from the light source 10c enters the interior of the display board 20 from the side surface 203, is guided, and exits from the front surface 201 of the display board 20 via the display pattern 30c, thereby displaying only the display pattern 30c. Light L2 emitted from the light source 10d enters the interior of the display board 20 from the side surface 203, is guided, and exits from the front surface 201 of the display board 20 via the display pattern 30d, thereby displaying only the display pattern 30d.

[0025] In other words, the display device 1 is provided with a plurality of display patterns provided on the front surface 201 or the back surface 202 of the display board 20, and at least one light source corresponds to each display pattern. The plurality of display patterns do not overlap with each other, for example, when the decorated areas of the display board 20 are viewed in the Y-axis direction. For example, the light source 10c is arranged on the surface of the display board 20 on which the display pattern 30c is provided, such that the area where light is guided inside the display board 20 includes only the area where the display pattern 30c is provided (i.e., does not include the area decorated with the display pattern 30d). For example, the light source 10d is arranged on the surface of the display board 20 on which the display pattern 30d is decorated, such that the area where light is guided inside the display board 20 includes only the area decorated with the display pattern 30d (i.e., does not include the area decorated with the display pattern 30c).

[0026] In order to reduce the distance between display patterns 30c and 30d on display board 20, it is preferable to increase the directivity of light L1, L2 emitted from light sources 10c, 10d. The spread angle of light L1 emitted from light source 10c corresponding to display pattern 30c is preferably set narrow enough to prevent light L1 from entering the area of ​​adjacent display pattern 30d. The spread angle of light L2 emitted from light source 10d corresponding to display pattern 30d is preferably set narrow enough to prevent light L2 from entering the area of ​​adjacent display pattern 30c. In order to increase the directivity, for example, laser light sources that emit highly directional laser light may be used as light sources 10c, 10d.

[0027] According to the display device 1, a single display panel 20 can be used to independently display a plurality of display patterns.

[0028] Furthermore, since a plurality of display patterns can be displayed using one display panel 20, the structure of the display device 1 can be simplified.

[0029] Furthermore, by forming the plurality of display patterns 30c and 30d by printing, deformation and processing of the display plate 20 is not required.

[0030] The number of display patterns and the number of light sources may be three or more.

[0031] First Modification of First Embodiment 7(a) and 7(b) are front and side views schematically illustrating the configuration of a display device 1a according to Variation 1 of Embodiment 1. FIGS. 7(a) and 7(b) illustrate an example in which cylindrical lenses 50c and 50d are provided as optical elements between the light sources 10c and 10d and the display board 20. The cylindrical lenses 50c and 50d are, for example, lenses filled with a refractive material. The cylindrical lenses 50c and 50d have curvature only in the long-side direction (X-axis direction) of the side surface 203 of the display board 20. The cylindrical lenses 50c and 50d can narrow the spread angle of the light beams L1 and L2 emitted from the light sources 10c and 10d in the X-axis direction. Anamorphic aspherical lenses or rotationally symmetric lenses may be used instead of the cylindrical lenses 50c and 50d.

[0032] According to the display device 1a, the directivity of the light beams L1 and L2 can be improved. Also, light sources other than laser light sources can be used as the light sources 10c and 10d. In all other respects, the display device 1a is the same as the display device 1 described above.

[0033] Second Modification of First Embodiment 8(a) and 8(b) are front and side views illustrating a schematic configuration of a display device 1b according to Modification 2 of Embodiment 1. FIGS. 8(a) and 8(b) illustrate an example in which anamorphic lenses 50e and 50f are provided as optical elements between the light sources 10e and 10f and the display board 20. The anamorphic lenses 50e and 50f are, for example, lenses filled with a refractive material. The anamorphic lenses 50e and 50f have a curvature in the long-side direction (X-axis direction) of the side surface 203 of the display board 20 and also in the thickness direction (Z-axis direction) of the side surface 203 of the display board 20. The anamorphic lenses 50e and 50f can narrow the divergence angle of the light beams L1 and L2 emitted from the light sources 10e and 10f. The optical element may be, for example, a hollow reflector, as long as it focuses light beams diverging at least in the long-side direction of the side surface of the display board 20.

[0034] According to the display device 1b, the directivity of the light beams L1 and L2 can be improved. Also, light sources other than laser light sources can be used as the light sources 10e and 10f. In all other respects, the display device 1b is the same as the display device 1.

[0035] Third Modification of First Embodiment 9(a) and 9(b) are a front view and a side view schematically illustrating the configuration of a display device 1c according to Modification 3 of Embodiment 1. The display device 1c differs from the display device 1 shown in FIGS. 6(a) and 6(b) in that the light source 10g is arranged to face the side surface 204 opposite to the side surface 203. In other respects, the display device 1c is the same as the display device 1 shown in FIGS. 6(a) and 6(b).

[0036] According to the display device 1c, the light sources 10d and 10g can be arranged facing different side surfaces 203 and 204 of the display board 20, which increases the degree of freedom in the installation positions of the light sources 10d and 10g. In all other respects, the display device 1c is the same as the display device 1 described above.

[0037] Fourth Modification of First Embodiment 6(a) and (b) to 9(a) and (b), examples have been described in which the directionality of light traveling inside the display board 20 is high, and as a result, the distance between two display patterns can be narrowed. In Variation 4 of Embodiment 1, a case will be described in which a boundary surface 23 that can change the traveling direction of light inside the display board 20 is provided between two display patterns 30c and 30d.

[0038] 10(a) and 10(b) are a front view and a side view schematically illustrating the configuration of a display device 1d according to Variation 4 of Embodiment 1. The boundary surface 23 is formed of a material with a refractive index different from that of the display panel 20. The boundary surface 23 is, for example, a cavity that is a region with a low refractive index. Means for providing a boundary surface that changes the direction of travel of light in part of the gap may, for example, be to subject the boundary surface to a reflective finish. Alternatively, the boundary surface may be optically polished. Alternatively, the boundary surface may be subjected to a scattering finish. Alternatively, the boundary surface may be subjected to an absorbing finish. By providing a region with a refractive index lower than that of the display panel 20, light is totally reflected at the boundary due to the difference in refractive index, preventing light from entering the region with the low refractive index.

[0039] According to the display device 1d, the display patterns 30h and 30i are separated by the boundary surface 23, so that even if light sources 10h and 10i with low directivity are used, the display patterns 30h and 30i can be independently controlled.

[0040] If the boundary surface 23 between the areas decorated with the display patterns 30h and 30i on the display board 20 is formed as a hollow, it is possible to reduce the weight of the display device 1d. Furthermore, in this case, it is possible to improve wind resistance against winds blowing perpendicular to the display device. In all other respects, the display device 1d is the same as the display device 1 described above.

[0041] Fifth Modification of First Embodiment 11(a) and 11(b) are a front view and a side view, respectively, that schematically show the configuration of a display device 1e according to Variation 5 of Embodiment 1. Figures 11(a) and 11(b) show an example in which a display panel 20 is divided into four grid-like sections by boundary surfaces 23 and 24. When the arrangement of the light-emitting surfaces makes it difficult to achieve total reflection due to differences in refractive index at the boundary surfaces 23 and 24, the direction of travel of light rays is changed by performing a reflective, scattering, or absorbing process on the boundary surfaces.

[0042] In the display device 1e, light sources 10h, 10i, 10j, and 10k irradiate light L1, L2, L3, and L4 onto display patterns 30h, 30i, 30j, and 30k, respectively. Because the display patterns 30h, 30i, 30j, and 30k are partitioned by boundary surfaces 23 and 24, it is possible to independently control the display of the display patterns 30h, 30i, 30j, and 30k even when a light source with low directivity is used.

[0043] The weight of the display device 1e can be reduced if the boundary surfaces 23 and 24 are formed as hollows in the display panel 20. In all other respects, the display device 1e is the same as the display device 1 described above.

[0044] Sixth Modification of First Embodiment 6(a) and (b) to 11(a) and (b) above, examples have been shown in which the positions of the display patterns are different in order to independently control the display of multiple display patterns on a single display board 20. However, multiple display patterns may be independently controlled on a single display board 20 by varying the wavelength of light emitted from light-emitting elements corresponding to the display patterns and entering the interior of the display board 20.

[0045] 12(a) and 12(b) are front views schematically illustrating the configuration of a display device 1f according to Variation 6 of Embodiment 1. In Fig. 12(a) and 12(b), in order to independently control the display of a plurality of display patterns 30c, 30d on a single display board 20, a light source 10m emits a plurality of types of light with different wavelengths.

[0046] The display patterns 30c and 30d are formed using transparent ink containing multiple types of light scattering particles that scatter light at different peak wavelengths. In other words, the transparent ink used contains light scattering particles that have wavelength selectivity in scattering light.

[0047] The wavelength range of light emitted from the light-emitting element corresponding to the display pattern 30c (or 30d) and entering the display board 20 overlaps with the wavelength range scattered by the transparent ink of the same display pattern 30c (or 30d) when white light is incident on the display board 20.

[0048] The spectrum of light emitted from the light-emitting element corresponding to display pattern 30c (or 30d) and entering display board 20 is different from, and does not overlap with, the spectrum scattered by the transparent ink when white light enters another non-corresponding display pattern 30d (or 30c). In other words, light emitted from the light-emitting element corresponding to display pattern 30c and entering display board 20 is scattered by display pattern 30c but not by display pattern 30d, and light emitted from the light-emitting element corresponding to display pattern 30d and entering display board 20 is scattered by display pattern 30d but not by display pattern 30c.

[0049] When there are two types of display patterns 30c, 30d, one of the display patterns 30c, 30d may be provided on the front surface 201, and the other on the back surface 202. In this way, when the display patterns 30c, 30d are formed on both the front surface 201 and the back surface 202 of the display board 20, the output light from the light-emitting element corresponding to the display pattern on the back surface 202 may be made larger than the output light from the light-emitting element corresponding to the display pattern on the front surface 201, so that the luminance of the display pattern on the front surface 201 and the luminance of the display pattern on the back surface 202 are equivalent.

[0050] Multiple display patterns 30c, 30d may be printed overlapping one another on the same surface. FIG. 13 is a front view including a partially enlarged view of a display device 1f. In this case, as shown in the partially enlarged view of FIG. 13, regions R1, R2, each partitioned to be sufficiently small relative to the size of the display pattern, may be printed so as to be alternately arranged. FIG. 14 is a diagram showing an example of decoration of each display pattern 30c, 30d. FIG. 15 is a diagram showing an example of decoration of multiple display patterns. FIG. 16 is a front view including another partially enlarged view of a display device 1f. As shown in FIG. 16, regions R1, R2 may be, for example, a grid of squares arranged so that adjacent regions are different colors. Regions R1, R2 may be a grid of rectangles, triangles, and circles arranged so that adjacent regions are different colors. Furthermore, in the overlapping portions of the multiple display patterns 30c, 30d, the spectrum scattered by the transparent ink when white light enters may include all or part of the spectrum of light emitted from the light-emitting elements corresponding to the overlapping display patterns 30 and entering the display board 20. Furthermore, the light emitted from the light source 10m may enter from any of the side surfaces of the display board 20. However, the number of multiple display patterns is not limited to two, and three or more types may be used. In the case of three or more types, sufficiently small partitioned regions may be arranged. For example, in the case of three types, hexagonal regions may be arranged so that adjacent regions are different colors.

[0051] According to the display device 1f, it is possible to independently control the display of a plurality of display patterns 30c, 30d on a single display board 20.

[0052] Furthermore, the display device 1f allows for a simplified structure while ensuring a variety of display pattern designs.

[0053] Furthermore, by forming the plurality of display patterns 30c and 30d by printing, deformation and processing of the display plate 20 is not required.

[0054] Furthermore, it is possible to independently control the display of a plurality of display patterns 30c and 30d in the same area.

[0055] In the case of Variation 6, for example, if the visibility of the multiple display patterns 30c and 30d is poor due to the difference in the density of the two colors, the visibility may be improved by adjusting the diameter or pitch of the dots, or both. However, to increase the resolution, it is desirable to make the pitch as small as possible.

[0056] Seventh Modification of First Embodiment 17(a) and 17(b) are front views schematically illustrating the configuration of a display device 1g according to Variation 7 of Embodiment 1. FIGS. 17(a) and 17(b) illustrate an example in which a wavelength-selecting filter 11n is provided between a light source 10n and a side surface 203 of the display board 20 to differentiate the wavelengths of light that enter the display board 20 corresponding to the display patterns 30c and 30d. In this example, the colors of the display patterns 30c and 30d may be a single color or multiple different colors. Furthermore, the colors of the light emitted from the light-emitting elements corresponding to the display patterns 30c and 30d and that enter the display board 20 may be a single color or multiple different colors. Furthermore, the multiple display patterns 30c and 30d may overlap each other on the display board 20.

[0057] The effects of the display device 1g are similar to those of the display device 1f.

[0058] Eighth Modification of First Embodiment By controlling the lighting of the light sources with the lighting control circuit 90, the lighting of the display patterns can be individually controlled, enabling dynamic display on the display board 20. For example, the current of the light source corresponding to at least one display pattern can be controlled, and the light can be flashed or the light intensity can be varied to create a highlighting effect.

[0059] Furthermore, if a plurality of display devices are controlled in a coordinated manner, the present invention can be applied to, for example, guidance displays on expressways or guidance displays on roads under construction.

[0060] FIGS. 18(a), (b), (c), and (d) are perspective views schematically illustrating the configuration of a display device according to Variation 8 of Embodiment 1. FIGS. 18(a), (b), (c), and (d) illustrate an example in which multiple display devices are stacked, with each display pattern partially overlapping and controlled to be illuminated in a time-division manner. FIGS. 18(a), (b), and (c) show stacked display devices a, b, and c, respectively. Display devices a, b, and c are decorated with display patterns a1, a2, and a3, display patterns b1, b2, and b3, and display patterns c1, c2, and c3, respectively. FIG. 18(d) shows display devices a, b, and c stacked in the z-axis direction. Here, display patterns a3 and b1, and display patterns b3 and c1 overlap in the same position on the XY plane when viewed from the -Z-axis direction. For example, when the display pattern is an arrow, by controlling the lighting of the arrow in a time-division manner with some parts overlapping, the arrow can be observed to be continuously (smoothly) lit, without being intermittently lit. Among the plurality of display units (display patterns a1, a2, and a3, or display patterns b1, b2, and b3, or display patterns c1, c2, and c3), the display patterns (display patterns a3 and b1, and display patterns b3 and c1) of adjacent display units (display unit A and display unit B, or display unit B and display unit C) may be arranged to be in contact with and overlap each other. Note that, assuming that the display patterns are viewed from the -Z-axis direction, they may overlap in the Z-axis direction. In other words, the display patterns may overlap in a direction perpendicular to the display panel.

[0061] The expressiveness and visibility of the display are improved by displaying a dynamic image on the display board 20. Furthermore, the flashing of light or varying intensity of light emission has the effect of highlighting the image.

[0062] Second Embodiment In the above embodiment, the display pattern 30 has been described as being used to decorate the display board 20. However, the display section 40d may be configured by attaching the film 25 having the display pattern 30 to the front surface 201 or the back surface 202 of the display board 20. The film 25 of the second embodiment can also be applied to the other embodiments.

[0063] 19(a) and 19(b) are a front view and a side view schematically showing the configuration of a display device 2 according to embodiment 2. Fig. 19(a) and 19(b) show an example in which a decorated film 25 is attached to a display board 20.

[0064] The film 25 is a plastic film made of, for example, acrylic or other plastic. The display board 20 is made of, for example, acrylic or other plastic. The display board 20 may also be made of glass. The film 25 is attached to the display board 20, for example, with an adhesive. By making the refractive indexes of the film 25, the adhesive, and the display board 20 approximately the same, total reflection is less likely to occur at the interface between the film and the adhesive, and at the interface between the adhesive and the display board 20. A plurality of display boards 20 to which the film 25 is attached may be arranged in the X-axis direction, the Y-axis direction, or both. Furthermore, the display boards 20 to which the film 25 is attached may be stacked in the Z-axis direction. Furthermore, it is preferable to use an adhesive that allows the film 25 to be peeled off.

[0065] Moreover, the display pattern 30 of the display unit shown in any one of FIGS. 6 to 17 may be formed by the film 25.

[0066] According to the display device 2, the display pattern 30 can be easily replaced by simply replacing the film 25.

[0067] Furthermore, although it is relatively difficult to directly process the curved display panel 20, when the film 25 is used, it is easy to form the display pattern 30 on the curved display panel 20, and the display device 2 is easy to manufacture.

[0068] Third Embodiment In the above embodiments, a case has been described in which light emitted from a light source enters the interior of display board 20 from side surface 203 or 204 of display board 20. In embodiment 3, a case will be described in which light emitted from a light source enters the interior from front surface 201 or back surface 202 of display board 20 via a light distribution control element, which is an incident optical element (i.e., a refractive optical element) attached to front surface 201 or back surface 202 of display board 20. The structure of embodiment 3 can be applied to other embodiments.

[0069] The display device according to the third embodiment may have a structure in which a plurality of display panels 20 each equipped with a light distribution control element are arranged in the X-axis direction, the Y-axis direction, or both of these directions. The display device according to the third embodiment may also have a structure in which display panels 20 each equipped with a light distribution control element are stacked in the Z-axis direction.

[0070] Figures 20(a) and 20(b) are a side view and a perspective view schematically showing the configuration of a display device 3 according to embodiment 3. Figure 21 is a side view showing the structure of light distribution control element 60 and display panel 20 of display device 3, and light rays LTC1, LTT1, and LTB1. Figure 22 is a side view showing the structure of light distribution control element 60 and display panel 20 of display device 3, and light rays LBC1, LBT1, and LBB1.

[0071] In display device 3, light distribution control element 60 is bonded to display board 20 at adhesive interface 60a. Light emitted from light source 10 enters display board 20 via light distribution control element 60, and is guided inside display board 20 in the -Y-axis direction and ±Z-axis directions.

[0072] The display board 20 is made of a transparent plastic such as PMMA. For example, the length of the display board 20 in the X-axis direction is 300 mm, and the length of the display board 20 in the Y-axis direction is 600 mm. The thickness of the display board 20 in the Z-axis direction is 6 mm. The display pattern 30 may be formed on either the front surface 201 or the back surface 202 of the display board 20.

[0073] Light source 10 has, for example, a plurality of 1 mm square light emitting diodes (LEDs). The LEDs are arranged in the X-axis direction. Light source 10 is also disposed at a position shifted toward display board 20 with respect to optical axis AX of light distribution control element 60. This makes it possible to guide the light from light source 10 inside display board 20 in the -Y-axis direction with high efficiency. This point will be described in detail later.

[0074] Light distribution control element 60 is formed of, for example, a transparent plastic such as PMMA, and is installed with its optical axis AX tilted at an angle β of 40 degrees, for example, with respect to the Y-axis direction, which is a direction parallel to front surface 201 of display board 20. By minimizing the difference in refractive index between display board 20 and light distribution control element 60 at adhesive interface 60a, it is possible to reduce interfacial reflection.

[0075] Fig. 21 shows the behavior of light rays emitted from the end portion of light source 10 in the -Z-axis direction. Fig. 21 shows, by a dashed-dotted line, a light ray LTT1 emitted from the end portion of light source 10 in the -Z-axis direction generally in the -Y-axis direction, by a solid line, a light ray LTC1 emitted from the end portion of light source 10 in the -Z-axis direction generally parallel to the optical axis AX, and by a dashed line, a light ray LTB1 emitted from the end portion of light source 10 in the -Z-axis direction generally in the +Z-axis direction.

[0076] The light ray LTT1 is emitted from the end of the light source 10 in the -Z-axis direction, is refracted at the incident surface T1, and is totally reflected at the optical surface T1a, traveling in a direction roughly parallel to the optical axis AX. The traveling light ray is totally reflected at the rear surface 202 of the display panel 20, traveling in the -Y-axis direction. Note that the optical surface T1b may be tilted toward the optical axis AX so that a portion of the light ray LTT1 reaches the rear surface 202. However, it is necessary to determine the tilt angle of the optical surface T1b with respect to the optical axis AX so as to satisfy the condition for total reflection at the rear surface 202. By tilting the optical surface T1b toward the optical axis AX, the length of the adhesive interface 60a in the Y-axis direction can be shortened.

[0077] Light ray LTC1 is emitted from the end of light source 10 in the -Z-axis direction in a direction generally parallel to optical axis AX, is refracted by convex surface 60b, and travels as a light ray generally parallel to optical axis AX. A portion of the traveling light ray is totally reflected by optical surface B1b, and after reaching the rear surface 202 of display board 20, is totally reflected again and travels in the -Y-axis direction. Most of light ray LTC1 is totally reflected by the rear surface 202 of display board 20, and travels in the -Y-axis direction.

[0078] Light ray LTB1 is emitted from the end of light source 10 in the -Z-axis direction generally in the +Z-axis direction, refracted at incident surface B1, and totally reflected at optical surface B1b, traveling as a parallel beam at an angle of approximately 13 degrees with respect to optical axis AX. A portion of the traveling light ray LTB1 is totally reflected at optical surface B1b and then totally reflected at the rear surface 202 of display panel 20, traveling in the -Y-axis direction. Most of the light ray LTB1 is totally reflected at the rear surface 202 of display panel 20, traveling in the -Y-axis direction. Optical surface B1b is tilted toward the optical axis AX. This is because, since light ray LTB1 travels at an angle of approximately 13 degrees with respect to optical axis AX, tilting the optical surface B1b to shorten the length of adhesive interface 60a in the Y-axis direction does not affect the travel of light ray LTB1. In Figures 21 and 22, optical surface B1b is tilted by more than 13 degrees with respect to optical axis AX. For example, the optical surface B1b is inclined at approximately 18 degrees with respect to the optical axis AX.

[0079] Fig. 22 shows the behavior of light rays emitted from the end portion of light source 10 in the +Z-axis direction. Fig. 22 shows light ray LBT1 emitted from the end portion of light source 10 in the +Z-axis direction generally in the -Y-axis direction by a dashed line, light ray LBC1 emitted from the end portion of light source 10 in the +Z-axis direction in a direction generally parallel to the optical axis AX by a solid line, and light ray LBB1 emitted from the end portion of light source 10 in the +Z-axis direction generally in the +Z-axis direction by a dashed line.

[0080] Light ray LBT1 is emitted from the end of light source 10 in the +Z-axis direction generally in the -Y-axis direction, is refracted at incident surface T1, and is totally reflected at optical surface T1a, traveling at an angle with respect to optical axis AX (i.e., in a direction gradually approaching optical axis AX). The traveling light ray is totally reflected at rear surface 202 of display panel 20, and travels in the -Y-axis direction.

[0081] The light ray LBC1 is emitted from the end of the light source 10 in the +Z-axis direction in a direction roughly parallel to the optical axis AX, is refracted, focused, and diffused by the convex surface 60b, and is totally reflected by the rear surface 202 of the display panel 20 to travel in the -Y-axis direction.

[0082] Light ray LBB1 is emitted from the end of light source 10 in the +Z-axis direction, is refracted at incident surface B1, and is totally reflected at optical surface B1b, becoming a light ray tilted with respect to optical axis AX (i.e., traveling in a direction gradually approaching optical axis AX). A portion of the traveling light ray LBB1 is totally reflected at rear surface 202 of display board 20 and travels in the -Y-axis direction. Most of light ray LBB1 is totally reflected at optical surface B1b, and then totally reflected at rear surface 202 of display board 20 and travels in the -Y-axis direction.

[0083] As such, it is necessary to take into account the light rays emitted from the end of the light source 10 in the -Z-axis direction and the end in the +Z-axis direction. Optical surface B1a shortens the length of the adhesive interface 60a in the Y-axis direction by tilting the light rays with respect to the optical axis AX. In addition, optical surface B1b needs to be designed so that the light rays emitted from the end in the -Y-axis direction satisfy the total reflection condition on the back surface 202 of the display panel 20. Here, for example, when the refractive index n1 of PMMA is 1.49, the refractive index n2 of air is 1, and α is the critical angle, the total reflection condition with the air interface can be calculated using the following formula: sin(α)=1 / 1.49 From this equation, α≈42.15 degrees is obtained. Therefore, when the rear surface 202 of the display panel 20 is used as the reference, 90-α=90-42.15≒47.8 In other words, when the light reaches the rear surface 202 of the display panel 20 at an inclination angle of 47.8 degrees or less with respect to the rear surface 202, the total reflection condition is satisfied.

[0084] Therefore, in the examples of FIGS. 21 and 22, the optical axis AX of the light distribution control element 60 is tilted by β=40 degrees with respect to the Y axis, but this angle β can be changed.

[0085] First Modification of Third Embodiment FIG. 23 is a side view showing the structures and light rays of light distribution control element 61 and display panel 20 of display device 3a according to Variation 1 of Embodiment 3. FIG. 23 shows the case where β=43 degrees. With β=43 degrees, optical surface T2b is slightly tilted toward optical axis AX to shorten adhesive interface 61a of light distribution control element 61 in the Y-axis direction (i.e., the end of optical surface T2b in the −Y-axis direction is moved in the +Y-axis direction). The length of adhesive interface 61a in the Y-axis direction can be set appropriately. It is necessary to prevent light ray L61b refracted at convex surface 61b, which is the incident surface of light distribution control element 61, from being refracted at optical surface T2b and emitted in the −Y-axis direction. In other words, it is necessary to ensure that the light ray refracted at convex surface 61b reaches front surface 201 of display panel 20 and is directed toward front surface 201 by total reflection at rear surface 202. From the above, it is considered preferable that the angle β between display panel 20 and optical axis AX is 43 degrees or less when light distribution control element 61 and display panel 20 are made of PMMA.

[0086] Furthermore, when display panel 20 is made of glass, it is necessary to take into consideration refraction at the adhesive interface. Note that when light distribution control element 61 is made of glass, the characteristics of each surface are the same as when it is made of PMMA.

[0087] Second Modification of Third Embodiment Fig. 24 is a side view showing the structures of light distribution control element 62 and display panel 20 of display device 3b according to Variation 2 of Embodiment 3, and light ray L62b. Fig. 24 shows the case where β = 29 degrees, as an example of a case where angle β is smaller than 40 degrees. Light distribution control element 62 has substantially the same shape as that shown in Figs. 21 and 22, but differs from those shown in Figs. 21 and 22 in angle β of optical axis AX with respect to the Y axis and the height of light distribution control element 62. Light ray L62b refracted at convex surface 62b, which is the incident surface of light distribution control element 62, reaches front surface 201 of display panel 20 and is directed toward front surface 201 due to total reflection at back surface 202.

[0088] 21 and 22, if the thickness of the display panel 20 is changed from 6 mm to 5 mm, it becomes difficult to guide light in the −Y-axis direction with high efficiency. However, in the example of Fig. 24, by tilting the optical surface T1b with respect to the optical axis AX (i.e., by moving the end of the optical surface T1b in the +Y-axis direction in the −Y-axis direction), it becomes possible to guide light with high efficiency even with a thickness of 5 mm.

[0089] Fig. 25 is a side view showing the structure of light distribution control element 62 and display board 20 of display device 3b2, and light ray L62bT. Fig. 25 shows the case where the thickness of display board 20 is 5 mm. Optical surface T3b has a larger inclination with respect to optical axis AX than optical surface T1b shown in Fig. 24. Therefore, in the example of Fig. 25, the length of adhesive interface 60a in the Y-axis direction is short.

[0090] Even if the angle β is smaller than 29 degrees, it is possible to guide light highly efficiently inside the display board 20, but as the length of the adhesive interface 62a increases, the displayable area of ​​the display board 20 becomes narrower, so it is preferable that the adhesive interface 62a be short in the Y-axis direction. Therefore, it is preferable that the angle β be 29 degrees or more.

[0091] Third Modification of Third Embodiment 26(a) and 26(b) are a side view and a perspective view schematically showing the configuration of a display device 3c according to embodiment 3. Fig. 27 is a side view showing the structure of a light distribution control element 70 and a display panel 20 of the display device 3c, and light rays.

[0092] The display panel 20 is made of a transparent plastic such as PMMA. The display panel 20 is 300 mm long in the X-axis direction and 600 mm long in the Y-axis direction. The thickness in the Z-axis direction is 5 mm. The display pattern 30 may be formed on either the front surface 201 or the back surface 202. The light source 10 has, for example, a plurality of 1 mm square LEDs, which are arranged in the X-axis direction.

[0093] Light distribution control element 70 is formed of a transparent plastic such as PMMA, and is installed with its optical axis AX tilted at an angle β=40 degrees, for example, with respect to display panel 20. By adhering it so as to eliminate the refractive index difference at adhesive interface 70a, it is possible to reduce interfacial reflection.

[0094] A light ray LCT2 emitted from the center of the light source 10 generally in the -Y axis direction is indicated by a dashed line, and a light ray LCB2 emitted from the center of the light source 10 generally in the +Z axis direction is indicated by a broken line.

[0095] After being emitted from the light source 10, the light ray LCT2 is refracted by the curved surface (e.g., a free-form surface) of the incident surface T2, suppressing the spread of the light, and is totally reflected by the optical surface T2a. The totally reflected light ray LCT2 becomes a light ray that is roughly parallel to the optical axis AX, and some of the light ray LCT2 is totally reflected by the optical surface T2b and then by the rear surface 202 of the display panel 20, and travels in the -Y axis direction. Most of the light ray LCT2 is totally reflected by the optical surface T2a, and then totally reflected by the rear surface 202, and travels in the -Y axis direction.

[0096] The optical surface T2b is parallel to the optical axis AX, but since the parallelism of the light ray LCT2 is low, part of the light ray LCT2 reaches the optical surface T2b.

[0097] After being emitted from the light source 10, the light ray LCB2 is refracted by the curved surface (e.g., a free-form surface) of the incident surface B2, suppressing the spread of the light, and is totally reflected by the optical surface B2a. The totally reflected light ray LCB2 is inclined at approximately 13 degrees with respect to the optical axis AX, becoming a substantially parallel light ray, and some of the light ray LCB2 is totally reflected by the optical surface B2b and then by the rear surface 202 of the display panel 20, traveling in the -Y-axis direction. Most of the light ray LCB2 is totally reflected by the optical surface B2a, and then by the rear surface 202, traveling in the -Y-axis direction. The optical surface B2b is inclined at 18 degrees with respect to the optical axis AX in order to shorten the length of the adhesive interface 70a in the Y-axis direction.

[0098] Fig. 28 is a side view that schematically shows the configuration of light distribution control element 70 and display board 20 of display device 3c. Fig. 28 shows the behavior of light rays emitted from the ends of light source 10 in the ±Z-axis directions. Light ray LT2 emitted from the end of light source 10 in the -Z-axis direction is shown by a dashed line, and light ray LB2 emitted from the end of light source 10 in the +Z-axis direction is shown by a broken line. It can be seen that both light rays are guided inside display board 20 in the -Y-axis direction.

[0099] Unlike the light distribution control element 60 of FIG. 21 , the light distribution control element 70 does not have a convex surface 60b. The light distribution control element 70 guides light rays emitted from the light source 10 to the display board 20 via the incident surface T2 and the incident surface B2. In addition, the recess 70b, which forms the boundary between the incident surface T2 and the incident surface B2, is offset in the −Z-axis direction from the optical axis AX of the light distribution control element 70. This increases the number of light rays emitted from the light source 10 that enter the incident surface B2 rather than the incident surface T2, thereby shortening the length of the adhesive interface 70a in the Y-axis direction. With this shape, when the light distribution control element 70 is inclined at β=40 degrees with respect to the front surface 201 of the display board 20, it becomes possible to guide light rays in the −Y-axis direction even if the thickness of the display board 20 is 5 mm.

[0100] Fourth Modification of Third Embodiment FIG. 29 is a side view schematically illustrating the configuration of light distribution control element 71 and display panel 20 of display device 3d according to Variation 4 of Embodiment 3. FIG. 29 illustrates a case where angle β of optical axis AX of light distribution control element 70 is 29 degrees. FIG. 29 illustrates light ray LT3 emitted from the end of light source 10 in the −Z-axis direction by a dashed line, and light ray LB3 emitted from the end of light source 10 in the +Z-axis direction by a broken line. Light ray LC3 emitted from the center of light source 10 by a solid line. It can be seen that both light rays are guided inside display panel 20 in the −Y-axis direction. With the configuration of FIG. 29, it can be seen that light can be guided inside display panel 20 in the −Y-axis direction with high efficiency, as with the display devices shown in FIGS. 21 and 22, even when angle β is 29 degrees.

[0101] The configuration in Fig. 29 differs from that in Fig. 28 in that the shapes of incident surface B2 and optical surface B2a of light distribution control element 70 are changed. Light ray LC3 emitted from the center of light source 10 in the +Z-axis direction is totally reflected by optical surface B3a, and then travels in the -Y-axis direction at an angle of approximately 14 degrees with respect to optical axis AX.

[0102] Even when β is 29 degrees or less, it is possible to guide light inside the display panel 20 with high efficiency, but it is preferable to shorten the length of the adhesive interface 71a in the Y-axis direction and widen the image display area of ​​the display panel 20.

[0103] 21 and 22, even when the angle β between the optical axis AX of the display board 20 and the light distribution control element 70 is 43 degrees, the light emitted by the light source 10 is guided inside the display board 20 in the -Y-axis direction with high efficiency.

[0104] According to the display devices of embodiment 3 and its variants 1 to 4, when it is difficult to install the light source 10 at a position opposite the side surface 203 of the display board 20, light can be incident inside the display board 20.

[0105] Furthermore, by laminating film 25 to a transparent member (for example, glass) such as a show window of an existing store, laminating light distribution control element 70 thereon, and arranging a light source, it becomes possible to install a display device on the existing transparent member. Therefore, an effect is obtained in that a new display device can be installed without renovating existing facilities.

[0106] The structure in which a display device is newly installed by laminating film 25 on a transparent member and arranging a light source therein can also be applied to other modifications of the third embodiment and other embodiments.

[0107] Fifth Modification of Third Embodiment (Light Source: 1 mm Square) Figures 30(a) and (b) are a side view and a perspective view schematically illustrating the configuration of a display device 3e according to embodiment 3. Figures 31, 32, and 33 are side views showing the structure and light rays of light distribution control element 72 and display panel 20 of display device 3e. In Modifications 1 to 4 of embodiment 3, the light distribution control element was formed with a configuration including multiple incident surfaces, but Modification 5 is different in that it has only one incident surface. This makes it possible to reduce the size of the light distribution control element compared to Modifications 1 to 4.

[0108] In display device 3e, light distribution control element 72 is bonded at adhesive interface 72a to display board 20. Light emitted from light source 10 enters display board 20 via light distribution control element 72 and is guided inside display board 20 in the −Y-axis direction and ±Z-axis directions.

[0109] The display board 20 is made of a transparent plastic such as PMMA. For example, the length of the display board 20 in the X-axis direction is 300 mm, and the length of the display board 20 in the Y-axis direction is 600 mm. The thickness of the display board 20 in the Z-axis direction is 5 mm, for example. The display pattern 30 may be formed on either the front surface 201 or the back surface 202 of the display board 20.

[0110] Light source 10 has, for example, a plurality of 1 mm square LEDs. The LEDs are arranged in the X-axis direction. The center of light source 10 is disposed on optical axis AX of light distribution control element 72.

[0111] Light distribution control element 72 is formed from a transparent plastic such as PMMA, and is installed with its optical axis AX tilted at an angle β of 11.5 degrees, for example, with respect to the Y-axis direction, which is a direction parallel to front surface 201 of display board 20. The length of incident surface IS72 in a direction perpendicular to optical axis AX, that is, in a direction parallel to the double-headed arrow indicating the length of light source 10 in FIG. 31 (1 mm in the figure), is 2 mm, for example. By minimizing the difference in refractive index between display board 20 and light distribution control element 72 at adhesive interface 72a, it is possible to reduce interfacial reflection.

[0112] 31 shows the behavior of light rays emitted from the end of light source 10 in the -Z-axis direction. Light ray LT51a1 is emitted from the end of light source 10 in the -Z-axis direction at an angle of -60 degrees relative to the plane formed by optical axis AX and the X-axis, approximately in the -Y-axis direction. Light ray LT51a2, light ray LT51a3, light ray LT51a4, and light ray LT51a5 are shown by dashed dotted lines, in the order of emission at angles in the +RX direction relative to light ray LT51a1. Light ray LT51a5 is emitted approximately in the -Y-axis direction at an angle of +60 degrees relative to the plane formed by optical axis AX and the X-axis. Here, clockwise rotation around the X-axis is defined as +RX rotation, clockwise rotation around the Y-axis is defined as +RY rotation, and clockwise rotation around the Z-axis is defined as +RZ rotation.

[0113] The behavior of each light ray will be explained. Light ray LT51a1 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT51a2 is totally reflected twice by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT51a3 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT51a4 is guided within light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT51a5 is totally reflected by bottom surface BS72 of light distribution control element 72, then totally reflected by top surface TS72, and further totally reflected by back surface 202 of display panel 20, and travels in the -Y-axis direction.

[0114] Light ray LT51a4 passes near the junction between lower surface BS72 of light distribution control element 72 and front surface 201 of display board 20, and reaches back surface 202 directly. If twice the distance D51 in the Y-axis direction from the junction between lower surface BS72 and front surface 201 to where light ray LT51a4 reaches back surface 202 is shorter than distance D72a in the Y-axis direction of adhesive interface 72a, light ray LT51a4 will be refracted at upper surface TS72 of light distribution control element 72 and emitted to the outside, and therefore, in terms of light utilization efficiency, it is preferable that twice the distance D51 in the Y-axis direction be longer than distance D72a in the Y-axis direction of adhesive interface 72a.

[0115] The angle γ formed between front surface 201 of display board 20 and lower surface BS72 of light distribution control element 72 is 13.5 degrees. The angle β formed between front surface 201 of display board 20 and optical axis AX is 11.5 degrees. Therefore, lower surface BS72 of light distribution control element 72 is inclined by 2 degrees in the +RX rotation direction with respect to optical axis AX. Note that if angle γ satisfies the following formula (1) or formula (2), light can be efficiently guided within display board 20. If adhesive interface 72a is to be narrowed in consideration of light leakage due to scattering by the adhesive layer at adhesive interface 72a, it is preferable to make angle γ small. Furthermore, if installation stability is important, it is preferable to make angle γ large in order to widen adhesive interface 72a. 7.5 degrees<γ<14.1 degrees…(1) β-4 degrees < γ < β+2.6 degrees … (2)

[0116] The dimensions of light distribution control element 72 in Fig. 31 (Modification 5) are, for example, a length W72 in the Y-axis direction of 23.9 mm and a length D72 in the Z-axis direction of 3.3 mm. For example, the length W60 in the Y-axis direction of Fig. 21 is 32.3 mm and the length D60 in the Z-axis direction of 17.2 mm; the length W61 in the Y-axis direction of Fig. 23 is 26.4 mm and the length D61 in the Z-axis direction of 14.8 mm; the length W62 in the Y-axis direction of Fig. 24 is 34.2 mm and the length D62 in the Z-axis direction of 11.8 mm; the length W70 in the Y-axis direction of Fig. 27 is 46.1 mm and the length D70 in the Z-axis direction of 26.7 mm; and the length W71 in the Y-axis direction of Fig. 29 is 50.1 mm and the length D71 in the Z-axis direction of 18.9 mm. It can be seen that the size of light distribution control element 72 in Fig. 31 (Modification 5) can be made smaller than the sizes of light distribution control elements 72 in Modifications 1 to 4.

[0117] 32 shows the behavior of light rays emitted from the center of light source 10. Light ray LC51b1 is emitted from the center of light source 10 at an angle of −60 degrees relative to the plane formed by optical axis AX and X axis, approximately in the −Y axis direction, followed by light ray LC51b2, light ray LC51b3, and light ray LC51b4, which are emitted in this order at angles in the +RX direction relative to light ray LC51b1, as shown by solid lines. Light ray LC51b4 is emitted at an angle of +60 degrees relative to the plane formed by optical axis AX and X axis, approximately in the −Y axis direction. Light ray LC51b3 is emitted at an angle parallel to optical axis AX.

[0118] The behavior of each ray will be explained. Light ray LC51b1 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display board 20, and travels in the -Y axis direction. Light ray LC51b2 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display board 20, and travels in the -Y axis direction. Light ray LC51b3 is guided within light distribution control element 72, then totally reflected by rear surface 202 of display board 20, and travels in the -Y axis direction. Light ray LC51b4 is totally reflected by lower surface BS72 of light distribution control element 72, then totally reflected by upper surface TS72, and then totally reflected by rear surface 202 of display board 20, and travels in the -Y axis direction.

[0119] 33 shows the behavior of light rays emitted from the +Z-axis direction end of light source 10. The dashed lines show light ray LB51c1, which is emitted from the +Z-axis direction end of light source 10 at an angle of -60 degrees relative to the plane formed by optical axis AX and the X-axis, approximately in the -Y-axis direction, followed by light ray LB51c2, light ray LB51c3, and light ray LB51c4, which are emitted at an angle in the +RX direction relative to light ray LB51c1. Light ray LB51c4 is emitted approximately in the -Y-axis direction at an angle of +60 degrees relative to the plane formed by optical axis AX and the X-axis.

[0120] The behavior of each ray will be explained. Light ray LB51c1 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB51c2 is totally reflected by upper surface TS72 of light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB51c3 is guided within light distribution control element 72, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB51c4 is totally reflected by lower surface BS72 of light distribution control element 72, then totally reflected by upper surface TS72, and then totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction.

[0121] The above is for the case where the thickness of display board 20 is 5 mm, but the thickness can also be 4 mm. In that case, the size of light distribution control element 72 can be, for example, 27.5 mm in the Y-axis direction (length W72) and 4.3 mm in the Z-axis direction (length D72). Although the size of light distribution control element 72 becomes slightly larger, it is possible to increase the light utilization efficiency even when display board 20 is made thinner.

[0122] 32, the top surface TS72 of the light distribution control element 72 is shaped so that on the +Y-axis direction side, an incident ray of light at angle AI51a (for example, an absolute value of 35.4 degrees) is totally reflected at angle AO51a (for example, an absolute value of 12.2 degrees) in a direction that reduces the angle with respect to the optical axis AX, and on the −Y-axis direction side, an incident ray of light at angle AI51b (for example, an absolute value of 6.3 degrees) is totally reflected at angle AO51b (for example, an absolute value of 11.1 degrees) in a direction that increases the angle with respect to the optical axis AX. Here, angle AO51b may be larger than angle AI51b so that the light ray is incident on rear surface 202 of display board 20 at an incident angle that satisfies the total reflection condition. As a result, light rays with a large emission angle relative to the optical axis AX are totally reflected by the rear surface 202 of the display board 20 at a smaller angle relative to the optical axis AX, and light rays with a small emission angle relative to the optical axis AX are totally reflected by the rear surface 202 of the display board 20 at a larger angle relative to the optical axis AX. In other words, it is possible to efficiently make the light emitted from the light source 10 incident on the rear surface 202 of the display board 20 at an incident angle that satisfies the condition for total reflection on the rear surface 202 of the display board 20.

[0123] Furthermore, by shaping the -Y-axis side of the upper surface TS72 of the light distribution control element 72 so that angle AO51b is larger than angle AI51b, the point of contact between the upper surface TS72 and the front surface 201 of the display panel 20 moves in the +Y-axis direction, making it possible to shorten the distance D72a in the Y-axis direction of the adhesive interface 72a, thereby improving light utilization efficiency.

[0124] Sixth Modification of Third Embodiment (Light Source: 3 mm Square) From the above, it has been found that modification 5 makes it possible to reduce the size of light distribution control element 72 and the thickness of display board 20. Therefore, modification 6 shows an example of light distribution control element 73 when the light source size is increased.

[0125] 34(a) and 34(b) are a side view and a perspective view schematically showing the configuration of a display device 3f according to embodiment 3. Figs. 35, 36, and 37 are side views showing the structure and light rays of a light distribution control element 73 and a display panel 20 of the display device 3f.

[0126] In display device 3f, light distribution control element 73 is bonded at adhesive interface 73a to display board 20. Light emitted from light source 10b enters display board 20 via light distribution control element 73 and is guided inside display board 20 in the -Y-axis direction and ±Z-axis directions.

[0127] The display board 20 is made of a transparent plastic such as PMMA. For example, the length of the display board 20 in the X-axis direction is 300 mm, and the length of the display board 20 in the Y-axis direction is 600 mm. The thickness of the display board 20 in the Z-axis direction is 5 mm, for example. The display pattern 30 may be formed on either the front surface 201 or the back surface 202 of the display board 20.

[0128] Light source 10b has, for example, a plurality of 3 mm square LEDs. The LEDs are arranged in the X-axis direction. The center of light source 10b is disposed on optical axis AX of light distribution control element 73. By using LEDs that are 3 mm square, it is possible to increase the amount of light emitted compared to when the LEDs are 1 mm square.

[0129] Light distribution control element 73 is formed of, for example, a transparent plastic such as PMMA, and is installed with its optical axis AX tilted at an angle β of, for example, 11.5 degrees with respect to the Y-axis direction, which is a direction parallel to front surface 201 of display board 20. The length of incident surface IS73 in a direction perpendicular to optical axis AX (a direction parallel to the length of light source 10b) is, for example, 4 mm. By minimizing the difference in refractive index between display board 20 and light distribution control element 73 at adhesive interface 73a, it is possible to reduce interfacial reflection.

[0130] Figure 35 shows the behavior of light rays emitted from the end of light source 10b in the -Z-axis direction. Light ray LT53a1 is emitted from the end of light source 10b in the -Z-axis direction at an angle of -60 degrees relative to the plane formed by optical axis AX and the X-axis, approximately in the -Y-axis direction. Light ray LT53a2, light ray LT53a3, light ray LT53a4, and light ray LT53a5 are shown by dashed dotted lines, in the order of emission at an angle in the +RX direction relative to light ray LT53a1. Light ray LT53a5 is emitted approximately in the -Y-axis direction at an angle of +60 degrees relative to the plane formed by optical axis AX and the X-axis. Here, clockwise rotation around the X-axis is defined as +RX rotation, clockwise rotation around the Y-axis is defined as +RY rotation, and clockwise rotation around the Z-axis is defined as +RZ rotation.

[0131] The behavior of each light ray will be explained. Light ray LT53a1 is totally reflected by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT53a2 is totally reflected twice by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT53a3 is totally reflected by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT53a4 is guided within light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LT53a5 is totally reflected by bottom surface BS73 of light distribution control element 73, then totally reflected by top surface TS73, and further totally reflected by back surface 202 of display panel 20, and travels in the -Y-axis direction.

[0132] Light ray LT53a4 passes near the junction between lower surface BS73 of light distribution control element 73 and front surface 201 of display board 20, and reaches back surface 202 directly. If twice the distance D53 in the Y-axis direction from the junction between lower surface BS73 and front surface 201 to where light ray LT53a4 reaches back surface 202 is shorter than distance D73a in the Y-axis direction of adhesive interface 73a, light ray LT53a4 will be refracted at upper surface TS73 of light distribution control element 73 and emitted to the outside, and therefore, in terms of light utilization efficiency, it is preferable that twice the distance D53 in the Y-axis direction be longer than distance D73a in the Y-axis direction of adhesive interface 73a.

[0133] The angle formed between front surface 201 of display panel 20 and lower surface BS73 of light distribution control element 73 is angle γb=10.9 degrees. The angle β formed between front surface 201 of display panel 20 and optical axis AX is 11.5 degrees. Therefore, lower surface BS73 of light distribution control element 72 is inclined by 0.6 degrees in the -RX rotation direction with respect to optical axis AX. By making angle γb smaller, distance D73a in the Y-axis direction of adhesive interface 73a is shortened, and light is prevented from being refracted at upper surface TS73 of light distribution control element 73 and emitted to the outside.

[0134] The dimensions of light distribution control element 73 in Fig. 31 (Variation 6) are, for example, a length W73 in the Y-axis direction of 30.2 mm and a length D73 in the Z-axis direction of 6.1 mm. For example, the length W60 in the Y-axis direction of Fig. 21 is 32.3 mm and the length D60 in the Z-axis direction of 17.2 mm; the length W61 in the Y-axis direction of Fig. 23 is 26.4 mm and the length D61 in the Z-axis direction of 14.8 mm; the length W62 in the Y-axis direction of Fig. 24 is 34.2 mm and the length D62 in the Z-axis direction of 11.8 mm; the length W70 in the Y-axis direction of Fig. 27 is 46.1 mm and the length D70 in the Z-axis direction of 26.7 mm; and the length W71 in the Y-axis direction of Fig. 29 is 50.1 mm and the length D71 in the Z-axis direction of 18.9 mm. It can be seen that the length in the Z-axis direction of light distribution control element 73 in Variation 6 can be made smaller than in Variations 1 to 4. Furthermore, considering that the length in the Y-axis direction is approximately 14% longer than the shortest length in Figure 23, but the length in the Z-axis direction is less than half, it can be seen that even though the size of light source 10b is tripled, the size of light distribution control element 73 can be made smaller than in variants 1 to 4.

[0135] Figure 36 shows the behavior of light rays emitted from the center of light source 10b. Light ray LC53b1 is emitted from the center of light source 10b at an angle of -60 degrees relative to the plane formed by optical axis AX and X axis, approximately in the direction of the -Y axis. Light ray LC53b2, light ray LC53b3, and light ray LC53b4 are shown in solid lines, in that order, emitted at an angle in the +RX direction relative to light ray LC53b1. Light ray LC53b4 is emitted at an angle of +60 degrees relative to the plane formed by optical axis AX and X axis, approximately in the direction of the -Y axis. Light ray LC53b3 is emitted at an angle parallel to the optical axis AX.

[0136] The behavior of each ray will be explained. Light ray LC53b1 is totally reflected by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LC53b2 is totally reflected by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LC53b3 is guided within light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction. Light ray LC53b4 is totally reflected by lower surface BS73 of light distribution control element 73, then totally reflected by upper surface TS73, and then totally reflected by rear surface 202 of display plate 20, and travels in the -Y axis direction.

[0137] 37 shows the behavior of light rays emitted from the end of light source 10b in the +Z axis direction. Light ray LB53c1 is emitted from the end of light source 10b in the +Z axis direction at an angle of −60 degrees relative to the plane formed by optical axis AX and the X axis, approximately in the −Y axis direction. Light ray LB53c2, light ray LB53c3, and light ray LB53c4 are shown in dashed lines, in that order, emitted at an angle in the +RX direction relative to light ray LB53c1. Light ray LB53c4 is emitted approximately in the −Y axis direction at an angle of +60 degrees relative to the plane formed by optical axis AX and the X axis.

[0138] The behavior of each ray will be explained. Light ray LB53c1 is totally reflected by upper surface TS73 of light distribution control element 73, then totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB53c2 is guided within light distribution control element 73, is totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB53c3 is totally reflected by lower surface BS73 of light distribution control element 73, then totally reflected by upper surface TS73, and again totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction. Light ray LB53c4 is totally reflected by lower surface BS73 of light distribution control element 73, then totally reflected by upper surface TS73, and again totally reflected by rear surface 202 of display plate 20, and travels in the -Y-axis direction.

[0139] 36 , the top surface TS73 of the light distribution control element 73 is shaped so that, on the +Y-axis direction side, an incident ray of light has an angle AI53a (for example, an absolute value of 35.4 degrees) that is totally reflected at an angle AO53a (for example, an absolute value of 16.2 degrees) in a direction that reduces the angle with respect to the optical axis AX, and the top surface TS73 of the light distribution control element 73 has a shape that, on the -Y-axis direction side, an incident ray of light has an angle AI53b (for example, an absolute value of 4.0 degrees) that is totally reflected at an angle AO53b (for example, an absolute value of 26.3 degrees) in a direction that increases the angle with respect to the optical axis AX. Here, angle AO53b may be larger than angle AI53b so that the light ray is incident on rear surface 202 of display board 20 at an incident angle that satisfies the total reflection condition. As a result, light rays with a large emission angle with respect to the optical axis AX are totally reflected by the rear surface 202 of the display board 20 at a smaller angle with respect to the optical axis AX, and light rays with a small emission angle with respect to the optical axis AX are totally reflected by the rear surface 202 of the display board 20 at a larger angle with respect to the optical axis AX. In other words, it is possible to efficiently make the light emitted from the light source 10b incident on the rear surface 202 of the display board 20 at an incident angle that satisfies the condition for total reflection with respect to the rear surface 202 of the display board 20.

[0140] In other words, light distribution control element 73, which is a refractive optical element, reflects first light that reaches a first region of top surface TS73 that is closer to light source 10b at a first exit angle that is smaller than the first angle of incidence, which is the angle of incidence of the first light, and reflects second light that reaches a second region of top surface TS73 that is farther from light source 10b than the first region at a second exit angle that is larger than the second angle of incidence, which is the angle of incidence of the second light. In this case, the first angle of incidence is larger than the second angle of incidence, and the first light and second light are guided by reflection to a second surface that is the front or back surface opposite the first surface (front or back surface).

[0141] Furthermore, by shaping the -Y-axis direction side of top surface TS73 of light distribution control element 73 so that angle AO53b is larger than angle AI53b, the point of contact between top surface TS73 and front surface 201 of display board 20 moves in the +Y-axis direction. This makes it possible to shorten distance D73a of adhesive interface 73a in the Y-axis direction, thereby improving light utilization efficiency.

[0142] 38(a) and 38(b) show an example of a side view and a perspective view of a light distribution control element 73 and a display panel 20 of a display device 3f according to a sixth modification of embodiment 3. The difference is that a light-shielding cover SH73 is provided to cover the light distribution control element 73.

[0143] Due to installation accuracy of light source 10b or shape error of light distribution control element 73, there is a possibility that unnecessary light will be emitted from upper surface TS73 of light distribution control element 73. Therefore, by providing a light-shielding cover SH73 so as to cover light distribution control element 73, it is possible to prevent the unnecessary light from turning into glare (bright light) and entering the viewer's eyes.

[0144] The light-shielding cover SH73 extends in the +X-axis direction, and is preferably black to block light, but may be any other color as long as it can block light. Furthermore, since the light distribution control element 73 is outside the display area, it is preferable that it is not visible to the viewer, and therefore the presence of the light-shielding cover SH73 is desirable.

[0145] A light-shielding cover or light-shielding sheet may also be provided on the +Z side of display board 20. This makes it impossible to observe light distribution control element 73 from the +Z axis direction side, and also makes it possible to block unnecessary light emitted from rear surface 202 of display board 20. Note that the same effect can be obtained in variant example 5 by providing a light-shielding cover.

[0146] Fourth Embodiment In the above embodiment, the display unit 40 of the display device has been described as having a single display panel 20. However, the display unit 40 may also have a visibility-enhancing member, which is a substantially transparent member for improving visibility, in addition to the display panel 20. The structure of embodiment 4 can also be applied to the other embodiments.

[0147] Fig. 39(a) is a perspective view showing a part of the configuration of the display device 4 according to embodiment 4, and Fig. 39(b) is a perspective view showing a schematic configuration of the display device 4 according to embodiment 4. The visibility improving member 80 is preferably installed behind the display board 20 so as not to impair the visibility of the display pattern 30. The visibility improving member 80 may be, for example, a transparency adjusting member having a lower transmittance than a normal transparent body.

[0148] The transparency adjusting member is, for example, processed as a neutral density filter. Alternatively, the transparency adjusting member may be a polymer dispersed liquid crystal. The neutral density filter may be either a transmissive or reflective type, but a transmissive type is preferred, as it has the advantage of being less affected by total reflection. The transmittance of the transparency adjusting member is, for example, 60% or less.

[0149] The visibility improving member 80 may be, for example, a diffusion plate having a diffusion treatment applied to its front surface, back surface, or both the front surface and back surface. Note that when the display board 20 is laminated, it is also possible to provide the visibility improving member 80.

[0150] According to the display device 4, by applying a dimming filter to the transparency adjusting member that constitutes the visibility improving member 80, the brightness (luminance) of the background is reduced and the contrast ratio of the display board 20 is improved, thereby improving the visibility of the display pattern 30.

[0151] Furthermore, when the transparency adjusting member constituting the visibility improving member 80 is made of polymer dispersed liquid crystal, the contrast ratio of the background decreases, and the visibility of the display pattern 30 improves.

[0152] When a visibility improving member 80 made of a transparent body that has been subjected to a diffusion process is used, the visibility of the display pattern 30 is improved by lighting the display pattern 30 against a blurred background.

[0153] Fifth Embodiment In the above embodiment, an example in which the display unit 40 includes a single display panel 20 has been described. However, the display unit 40 may also include stacked display panels 20. However, when stacked display panels 20 are included, moire may occur due to periodic decoration in the multiple display patterns 30. The periodic structure may be, for example, dots in printing. To reduce moire, for example, the display patterns 30 (e.g., decorative areas) of the stacked display panels 20 may be decorated so that they do not overlap each other when viewed from the observation position. Furthermore, to reduce moire, the planar periods of the decorations in the multiple display panels 20 may be matched, and the decorated surfaces may overlap (i.e., the display patterns may be overlapped so that they are in contact with each other). The structure of embodiment 5 can also be applied to the other embodiments.

[0154] FIG. 40 is a side view schematically illustrating the configuration of a display device 5 according to embodiment 5. FIG. 40 shows an example in which display panels 20 are stacked to minimize the effect of moire on visibility. For example, if the thickness of the display panel 20 (i.e., the length of the short side of the side surface 203 in the Z-axis direction) is 4 mm or less, as shown in FIG. 40 , the effect of moire on visibility is minimal if two display patterns 30 are stacked on top of each other with the decorative surface facing inward, resulting in a total of three layers. This is because, by matching the planar periods, no spatial periodic shift occurs between the two overlapping decorative surfaces (i.e., two display patterns in contact with each other), and therefore moire is not visible. Furthermore, the third display pattern 30 (i.e., the topmost display pattern 30 in FIG. 40 ) is positioned 4 mm away from the other display patterns, and therefore some spatial periodic shift occurs, but the effect on visibility is minimal.

[0155] The display device 5 includes the stacked display panels 20 and the plurality of display patterns 30, and is therefore capable of displaying a variety of display patterns.

[0156] Furthermore, since the decorative surfaces of the two display patterns 30 are overlapped, the influence of moire on visibility can be suppressed.

[0157] Sixth Embodiment In the above-described embodiments, examples have been described in which the display device is mainly composed of a light source and a display unit. In the sixth embodiment, the display device includes a sensor unit disposed behind the display unit 40 in addition to the light source 10 and the display unit 40.

[0158] Fig. 41 is a diagram schematically illustrating the configuration of a display device according to embodiment 6. The display device shown in Fig. 41 includes a light source 10, a display unit 40, and a sensor unit that detects the presence of an object (e.g., a finger 606) in a position close to the display board 20 of the display unit 40. The display device according to embodiment 6 is applicable to a non-contact type control panel, which is an operating device for operating equipment or facilities.

[0159] The sensor unit of the display device according to the sixth embodiment includes, for example, a sensor light source 602 that emits light (sensor light), a light receiving unit 603 that has a light receiving element that detects the light, and a bandpass filter 601 that passes light in a predetermined wavelength band. The display panel 20 that constitutes the display unit 40 is made of a material that transmits the light emitted from the sensor light source 602.

[0160] The sensor light source 602 is, for example, a semiconductor laser. The light emitted from the sensor light source 602 is not visible light but, for example, near-infrared light (for example, wavelength 850 nm). An optical element such as a lens may be provided immediately after the sensor light source 602.

[0161] The light receiving unit 603 receives light coming from the direction of the display unit 40. The light receiving unit 603 is, for example, a photodiode, a CCD (Charge Coupled Device) image sensor, or a CMOS (Complementary Metal Oxiside Semiconductor) image sensor. An optical element such as a lens may be provided immediately in front of the light receiving unit 603.

[0162] The bandpass filter 601 selectively transmits light in the wavelength band of the sensor light source 602. The bandpass filter 601 may be, for example, specified to transmit light having a full width at half maximum of 50 nm or less centered on the peak wavelength of the sensor light source 602.

[0163] In the display device of Figure 41, light is emitted from a sensor light source 602, passes through a bandpass filter 601, passes through the display board 20 from the back to the front, is reflected by a finger 606, which is an object, passes through the display board 20 from the front to the back, and passes through the bandpass filter 601, and then enters a light receiving unit 603.

[0164] Fig. 42 is a diagram schematically illustrating the configuration of a display device according to Variation 1 of Embodiment 6. The display device illustrated in Fig. 42 includes a sensor light source 602, a light receiving unit 603, a bandpass filter 601, and a beam splitter 604. By including beam splitter 604, the optical axis of sensor light source 602 and the optical axis of light receiving unit 603 can be aligned.

[0165] In the display device of Figure 42, light is emitted from a sensor light source 602, passes through a beam splitter 604 and a bandpass filter 601, passes through the display board 20 from the back to the front, is reflected by a finger 606 which is an object, passes through the display board 20 from the front to the back, passes through the bandpass filter 601, and is reflected by the beam splitter 604, and enters a light receiving unit 603.

[0166] FIG. 43 is a diagram schematically illustrating a configuration of a display device according to Modification 2 of Embodiment 6. The display device illustrated in FIG. 43 includes a sensor light source 602, a light receiving unit 603, a bandpass filter 601a, and a dichroic mirror 605. The dichroic mirror 605 transmits light in the visible wavelength band (e.g., 380 nm to 780 nm) and reflects light in the wavelength band of the sensor light source 602. Depending on the color displayed on the display unit 40 or the combination of the wavelengths used by the display unit 40 and the sensor light source 602, the dichroic mirror 605 can deflect light to make optical components such as the sensor light source 602 and the light receiving unit 603 less visible to the observer (at the position of the finger 606). Furthermore, if the display unit 40 and the dichroic mirror 605 are transparent, a see-through structure can be achieved, allowing objects behind them (such as other display units and guide signs) to be visible.

[0167] In the display device of Figure 43, light is emitted from sensor light source 602, passes through bandpass filter 601a, is reflected by dichroic mirror 605, passes through display board 20 from the back to the front, is reflected by finger 606, which is the object, passes through display board 20 from the front to the back, is reflected by dichroic mirror 605, and passes through bandpass filter 601a, and then enters light receiving unit 603.

[0168] When a finger 606 is brought close to the display board 20 of any of the display devices in FIGS. 41 to 43, light emitted from the sensor light source 602 is reflected by the finger 606, and the reflected light is received by the light receiving unit 603. The control unit 610 can determine whether or not an input operation has been performed by the finger 606 based on a change in the intensity of the detected light in the light receiving unit 603. The control unit 610 may determine whether or not an input operation has been performed by the finger 606 by ToF (Time of Flight). The control unit 610 may perform lighting control and switching control of the display pattern 30 based on the determination of the input. The control unit 610 is configured with a processing circuit. The processing circuit may be configured with a processor that executes a program as software stored in a memory.

[0169] It is desirable that the color of the display pattern 30 on the display board 20 has a sufficiently large contrast ratio in brightness with respect to the color of the bandpass filters 601, 601a. ​​For example, when the light emitted from the sensor light source 602 is near-infrared light, the color of the bandpass filters 601, 601a is black. In contrast, the color of the display pattern 30 is a high-brightness color such as white.

[0170] The display device of any of Figures 41 to 43 employs a structure that integrates a configuration for displaying information with a sensor section that detects an object such as a finger 606 in a non-contact manner, and is therefore expected to save space.

[0171] Furthermore, by using any of the display devices shown in FIGS. 41 to 43, the structure of the sensor unit can be made invisible from the outside, which allows for improved design.

[0172] The configuration of the sensor section of any of the display devices shown in FIGS. 41 to 43 can be applied to any of the above-described embodiments. [Explanation of symbols]

[0173] 1, 1a~1g, 2, 3, 3a~3c, 3b2, 4, 5 display device, 10, 10c, 10d, 10e, 10f, 10h, 10i, 10m, 10n light source, 20 display board, 30, 30c, 30d, 30h, 30i, 30j, 30k display pattern, 40, 40c, 40d display, 201 front, 202 back, 203, 204 side, L0~L4, L6, L7 light.

Claims

1. In a display device for displaying a display object, a plurality of light sources each emitting light of a different wavelength; a display unit having a transparent display plate, configured to have a plurality of display patterns with different peak wavelengths of scattered light on at least one of the front and back surfaces of the single display plate in order to display the display target in response to light emitted by the light source, the display pattern being in a visible display state when the light source is emitting light scattered by the display pattern, and the display pattern being in a transparent non-display state when the light source is not emitting light scattered by the display pattern; a lighting control circuit that controls the plurality of light sources so as to switch between light sources to be turned on among the plurality of light sources, thereby switching the wavelength of light incident on the single display panel and independently switching between display and non-display of each of the plurality of display patterns; Equipped with the plurality of light sources include a light source that emits light of a first wavelength among the light of different wavelengths, the plurality of display patterns are formed by transparent ink containing a plurality of types of light scattering particles having different peak wavelengths of scattered light, and the light of the first wavelength is scattered more significantly by the first display pattern than by the second display pattern; the display pattern has a plurality of divided minute regions, The wavelengths of light scattered in adjacent regions among the plurality of regions are different. A display device characterized by:

2. The replaceable display pattern is provided on a film attached to at least one of the front and back surfaces of the display plate with an adhesive, The display panel, the adhesive, and the film have similar refractive indices.

2. The display device according to claim 1.

3. The plurality of display patterns are formed by transparent ink containing a plurality of types of light scattering particles that scatter light with different peak wavelengths.

3. The display device according to claim 1 or 2.

4. Further comprising a refractive optical element bonded to the display panel, The light emitted from the light source passes through the refractive optical element and enters the inside of the display panel from the front or rear surface of the display panel, and is guided in a direction along the front or rear surface, The refractive optical element is a first incident surface that refracts light emitted toward the display panel; a first reflecting surface having a curved shape that reflects light refracted by the first incident surface; a second reflecting surface having a planar shape extending from the first reflecting surface; a second incident surface that refracts light emitted to the opposite side of the display panel; a third reflecting surface having a curved shape that reflects the light refracted by the second incident surface; a fourth reflecting surface having a flat shape extending from the third reflecting surface; have 4. The display device according to claim 1, wherein the display device is a display device having a plurality of light sources.

5. The angle of the second reflecting surface relative to the surface of the display plate is smaller than the angle of the optical axis of the refractive optical element relative to the surface of the display plate.

5. The display device according to claim 4.

6. Further comprising a refractive optical element bonded to the display panel, The light emitted from the light source passes through the refractive optical element and enters the inside of the display panel from the front or rear surface of the display panel, and is guided in a direction along the front or rear surface, the refractive optical element has an incident surface onto which light emitted from the light source is incident, an upper surface, a lower surface opposite to the upper surface, and an adhesive interface opposite to the upper surface; The adhesive interface is bonded to a first surface, which is the front surface or the back surface, of the display panel; The upper surface is a free-form surface.

3. The display device according to claim 1 or 2.

7. The refractive optical element is configured such that, among the light emitted from the end portion on the upper surface side of the light source, the light passes through the contact point on the light source side of the adhesive interface and travels toward a second surface which is the back surface or the front surface opposite the first surface, The distance in a first direction, which is a direction parallel to the second surface, from the contact point on the light source side to the position of the second surface of the display panel that first reaches after passing through the adhesive interface is twice longer than the length of the adhesive interface in the first direction.

7. The display device according to claim 6.

8. The refractive optical element is When the angle between the incident light and the optical axis of the refractive optical element is defined as an incident angle, and the angle between the emitted light and the optical axis of the refractive optical element is defined as an emission angle, a first light beam reaching a first region of the upper surface closer to the light source is reflected at a first exit angle that is smaller than a first incident angle that is an incident angle of the first light beam; reflecting second light reaching a second region of the upper surface that is farther from the light source than the first region at a second exit angle that is larger than a second incident angle that is an incident angle of the second light; the first angle of incidence is greater than the second angle of incidence; The first light and the second light are guided by the reflection to a second surface, which is the back surface or the front surface opposite to the first surface.

8. The display device according to claim 6 or 7.

9. a light-shielding cover provided to cover the refractive optical element; The display device according to any one of claims 6 to 8.

10. a plurality of the light sources and a plurality of the display units are stacked; The display patterns of adjacent display sections among the plurality of display sections are arranged so as to contact and overlap each other, the plurality of display patterns are arrows, The plurality of display patterns are independently controlled to be illuminated in a time-division manner.

3. The display device according to claim 1 or 2.

11. The light source has two light sources, The display unit has two of the above-mentioned displays, The two display units are stacked, The display patterns of the two display units are arranged so as to overlap each other in a direction perpendicular to the display units.

3. The display device according to claim 1 or 2.

12. a sensor unit on at least one of the front and back surfaces of the display board that detects an object present on the opposite side of the one surface of the display board; The sensor unit a sensor light source that emits sensor light; a light receiving unit that detects the sensor light that has passed through the display plate from the one surface to the opposite side of the one surface, been reflected by the object, passed through the display plate from the opposite side of the one surface to the one surface, and been reflected by a dichroic mirror; The dichroic mirror reflects light in the wavelength band of the sensor light source and transmits light in the visible light wavelength band between the display panel and the sensor light source and light receiving unit.

12. The display device according to claim 1, wherein the display device is a display device having a plurality of light sources.

13. Visible light that is incident on the surface of the dichroic mirror opposite to the display panel and that is emitted from the surface of the dichroic mirror facing the display panel travels straight and is incident on the display panel.

13. The display device according to claim 12.

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