Display device

Abstract

The invention provides a display device capable of being thinned. This aerial image display device (100) is provided with: a housing (110); a beam splitter (120) formed on the surface of the housing (110); a retro-reflective sheet (130) disposed so as to face the beam splitter (120), the retro-reflective sheet (130) having formed therein a notch or an opening for generating a pattern of an original image of the aerial image; a light source (140) that irradiates the retro-reflective sheet (130) from the rear surface side; and a metamaterial layer (150), which is disposed between the beam splitter (120) and the retroreflective sheet (130), and which has a refractive index of less than 1. The aerial image (P) of the pattern (Q) irradiated by the light source (140) is displayed at a floating distance (Lb) above the housing (110) (Lb > Lx).

Description

Technical Field

[0001] The present invention relates to a display device having a function of displaying an image in the air using retroreflection. Background Art

[0002] Aerial Imaging by Retro - Reflection (AIRR) using retroreflection is known. For example, Patent Document 1 discloses a display device including a semi - transparent and semi - reflective mirror, an image output device that outputs light to one surface of the semi - transparent and semi - reflective mirror, and a retro - reflection member that is disposed between the image output device and the semi - transparent and semi - reflective mirror and has a plurality of openings formed therein. In addition, Patent Document 2 discloses an aerial display device including: a planar light emitter having a light - emitting portion; a retro - reflection sheet disposed on the light - emitting surface side of the planar light emitter and having a plurality of through - holes representing a pattern for aerial display at positions corresponding to the light - emitting portions; and a semi - transparent and semi - reflective mirror disposed on the light - emitting surface side of the retro - reflection sheet.

[0003] [Prior Art Documents]

[0004] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid - Open No. 2018 - 81138

[0006] [Patent Document 2] Japanese Patent Application Laid - Open No. 2022 - 140264 Summary of the Invention

[0007] As an AIRR - type aerial display system, there is a system that uses an LED as a light source and displays a fixed display pattern in the air. In order to achieve miniaturization and thinning, such a display device is configured such that the optical components face each other. One structural example is shown in Figure 1 FIG.

[0008] Figure 1 (A) of FIG. is a schematic top view of a conventional aerial image display device, Figure 1 (B) of FIG. is a schematic cross - sectional view taken along line A - A thereof. The aerial image display device 10 includes: a beam splitter 30 mounted on the surface of a rectangular housing 20; a retro - reflection sheet 40 disposed inside the housing 20 so as to face the beam splitter 30; and a light source 50 such as an LED. A cut or opening 42 is formed in the retro - reflection sheet 40, and the cut 42 generates a pattern (fixed display pattern) Q that becomes the original image of the aerial image P. Figure 1 The aerial image P in (A) of FIG. illustrates an icon indicating the on / off of the power supply of the device.

[0009] When irradiated from the back side of the retroreflective sheet 40 with the light source 50, the light that has passed through the notch 42 is retroreflected between the retroreflective sheet 40 and the beam splitter 30, and the aerial image P of the pattern Q is displayed above the housing 20. The suspension distance L1 of the aerial image P is equivalent to the distance L2 from the beam splitter 30 to the retroreflective sheet 40 (or the pattern Q). If the distance L2 is reduced in order to thin the height H of the housing 20, the suspension distance L1 of the aerial image P becomes shorter, and there is a problem that the feeling of floating of the aerial image P becomes weaker.

[0010] An object of the present invention is to solve such a conventional technical problem and provide a display device capable of achieving thinning while maintaining the suspension distance of the aerial image.

[0011] The display device of the present invention capable of displaying an aerial image using retroreflection includes: an optical component that transmits a part of the incident light and reflects the remaining light; a retroreflective component that is arranged to face the optical component and has a notch or opening formed with a pattern for generating an original image of the aerial image; a light source that irradiates the retroreflective component from the back side; and a transparent intermediate layer that is arranged between the optical component and the retroreflective component and is made of a substance having a refractive index less than 1.

[0012] In one mode, the transparent intermediate layer is made of a metamaterial. In one mode, the aerial image is displayed above the optical component at a suspension distance corresponding to the refractive index of the transparent intermediate layer. In one mode, the optical component is a semi-transmissive semi-reflective mirror, a beam splitter, or a polarization beam splitter.

[0013] [Advantages of the Invention]

[0014] According to the present invention, by providing an intermediate layer having a refractive index less than 1 between the optical component and the retroreflective component, it is possible to reduce the refraction angle of the light transmitted through the optical component and form the aerial image at a farther distance. Therefore, it is possible to reduce the distance between the optical component and the retroreflective component to achieve thinning of the display device, and on the other hand, it is possible to increase the suspension distance of the aerial image. [Brief Description of the Drawings]

[0015] Figure 1 (A) is a top view of a conventional aerial image display device, Figure 1 (B) is a schematic cross-sectional view taken along line A-A thereof.

[0016] Figure 2 is a top view of the aerial image display device according to an embodiment of the present invention.

[0017] Figure 3 is a diagram showing simulation results of an aerial image generated by a conventional aerial image display device and simulation results of an aerial image generated by the aerial image display device according to this embodiment. Detailed implementation mode

[0018] The display device of the present invention displays an aerial image using retroreflection in a three-dimensional space even without wearing special glasses or the like. It should be noted that the drawings referred to in the following description of the embodiments include displays exaggerated for easy understanding of the invention and do not directly represent the shape and scale of an actual product.

[0019] [Embodiment]

[0020] Next, the embodiments of the present invention will be described in detail. Figure 2 is a schematic cross-sectional view of the aerial image display device according to the embodiment of the present invention, and this cross-sectional view corresponds to Figure 1 the cross-section along line A-A of (A) in

[0021] The aerial image display device 100 of the present embodiment is configured to include, for example: a rectangular housing 110, a beam splitter 120 mounted on the surface of the housing 110, a retroreflective sheet 130 mounted in the housing 110 so as to face the beam splitter 120, a light source 140 disposed on the back side of the retroreflective sheet 130, and a metamaterial layer 150 disposed so as to fill the space between the beam splitter 120 and the retroreflective sheet 130.

[0022] The beam splitter 120 is an optical component that transmits a part of the incident light and reflects the remaining light, that is, an optical component that separates the incident light into transmitted light and reflected light at a certain ratio. The beam splitter 120 is, for example, a semi-transmissive semi-reflective mirror. In addition, in the case of using polarized light, the beam splitter 120 uses a polarization beam splitter.

[0023] The retroreflective sheet 130 is disposed so as to face the beam splitter 120. The retroreflective sheet 130 is an optical component that reflects light in the same direction as the incident light, and is composed of, for example, prism-type retroreflective elements such as triangular pyramid-type retroreflective elements and cube corner retroreflective elements, and bead-type retroreflective elements.

[0024] The shape and size of the retroreflective sheet 130 are not particularly limited, and a notch or opening for forming a pattern Q for generating an original image that becomes the aerial image P is formed in the retroreflective sheet 130. For example, as shown in (A) of Figure 1 , the pattern Q is an icon indicating the on / off of the power supply. However, the type (characters, icons, etc.) and number of patterns formed on the retroreflective sheet 130 are arbitrary.

[0025] A light source 140 is disposed on the back side of the retroreflective sheet 130. The light source 140 is not particularly limited. For example, it is a display light source such as an LED light source or a liquid crystal, a projection light source such as a projector, or the like. In the case of using an LED light source, for example, a plurality of LEDs may be arranged in a line or a plane to irradiate the entire back surface of the retroreflective sheet 130 efficiently and without omission. In addition, a diffusion plate or a diffusion sheet may be used in combination to uniformly irradiate the back side of the retroreflective sheet 130.

[0026] A transmissive transparent material having a refractive index less than 1, i.e., a metamaterial layer 150, is filled or disposed between the beam splitter 120 and the retroreflective sheet 130. The metamaterial layer 150 is formed with a substantially constant film thickness such that its upper surface is in contact with the beam splitter 120 and its bottom surface is in contact with the retroreflective sheet 130. However, the film thickness and shape of the metamaterial layer 150 are not particularly limited.

[0027] A metamaterial refers to an artificial substance or artificial material that performs actions not present in natural substances. Here, it has the property of having a refractive index less than 1. Metamaterials usually periodically arrange fine structures and patterns, thereby enabling control of the refraction of light. Constituent elements of general metamaterials include, for example, metals, dielectrics, magnetic materials, carbon nanotubes, metal nanowires, silicon, or plastics. By sandwiching the metamaterial layer 150, the refraction angle of the light transmitted through the beam splitter 120 can be made smaller than when there is an air layer without the metamaterial layer 150.

[0028] Next, the operation of the aerial image display device 100 of the present embodiment will be described. Light from the light source 140 irradiates the back side of the retroreflective sheet 130, and the irradiated light passes through the cuts or openings formed in the retroreflective sheet 130, thereby generating a pattern Q that is the original image of the aerial image P. A part of the light transmitted through the notches or openings is reflected by the beam splitter 120 via the metamaterial layer 150. Then, the light retroreflected by the retroreflective sheet 130 is transmitted through the beam splitter 120 via the metamaterial layer 150, and the aerial image Q of the pattern P is imaged again.

[0029] By filling the metamaterial layer 150 between the beam splitter 120 and the retroreflective sheet 130, the refraction angle of the light transmitted through the beam splitter 120 becomes smaller compared to when the space is an air layer, and the aerial image P can be imaged at a distance, that is, the suspension distance Lb can be increased.

[0030] As a comparative example, Figure 2The aerial image P1 shown is the imaging position when there is no metamaterial layer 150 between the beam splitter 120 and the retroreflector 130 and the space is set as an air layer. At this time, the suspension distance La is equivalent to the distance Lx between the beam splitter 120 and the retroreflector 130 (or pattern Q) (La = Lx). On the other hand, the aerial image P is the imaging position when the space of the distance Lx between the beam splitter 120 and the retroreflector 130 is filled with the metamaterial layer 150, and its suspension distance Lb is larger than the suspension distance La when there is no metamaterial layer 150 (Lb > La). The suspension distance Lb is roughly determined according to the refractive index of the metamaterial layer 150.

[0031] Thus, even if the interval Lx between the beam splitter 120 and the retroreflector 130 is shortened, that is, the thinning of the housing is achieved, the suspension distance Lb of the aerial image P can be extended, and a sense of floating can be obtained.

[0032] In addition, in another aspect of the present embodiment, the light source 140 may also be configured to include a polarizing plate or a polarization filter, and the back side of the retroreflector 130 is irradiated with polarized light. In this case, a λ / 4 film is provided as a retardation film on the front side of the retroreflector 130, and a polarization beam splitter is used for the beam splitter 120. The polarization beam splitter transmits a part of the light in a certain polarization state and reflects the remaining part. The polarization state of the polarizing plate or the polarizing film is determined in relation to the polarization state of the polarization beam splitter.

[0033] Figure 3 The upper side shows the simulation result of the aerial image generated by the conventional liquid crystal display device, and the lower side shows the simulation result of the aerial image generated by the liquid crystal display device of the present embodiment. In the conventional liquid crystal display device, there is an air layer between the retroreflector and the polarization beam splitter, and the aerial image generated at the suspension distance equal to the thickness of the air layer is visually recognized from the eye point.

[0034] In contrast, in the liquid crystal display device of the present embodiment, a transparent body with a refractive index smaller than 1, that is, a metamaterial layer, is buried instead of the air layer, thereby displaying an aerial image whose imaging position extends compared to the air layer, and an aerial image with a larger suspension distance compared to the air layer is visually recognized from the eye point.

[0035] The aerial image display device of the present embodiment can be applied to the display of information of all devices and user input. For example, it can be applied to computer devices, in-vehicle electronic devices, ATMs in banks, ticket vending machines at stations, input buttons of elevators, etc.

[0036] As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to specific embodiments, and various modifications and changes can be made within the scope of the gist of the invention described in the claims.

[0037] [Explanation of Reference Numerals]

[0038] 100: Aerial image display device

[0039] 110: Housing

[0040] 120: Beam splitter

[0041] 130: Retroreflective sheet

[0042] 140: Light source

[0043] 150: Metamaterial layer

[0044] P: Aerial image

[0045] Q: Pattern (original image)

Claims

1. A display device capable of displaying an aerial image by utilizing retro-reflection, the display device comprising: An optical component that transmits a portion of incident light and reflects the remaining light; A retro-reflective component is arranged in a manner opposite to the optical component and is formed with a notch or opening of a pattern for generating an original image of an aerial image; a light source, irradiating the retro-reflective component from the back side; as well as The transparent intermediate layer is disposed between the optical component and the retroreflective component and is made of a material having a refractive index less than 1.

2. The display device according to claim 1, The transparent intermediate layer is made of metamaterial.

3. The display device according to claim 1, The aerial image is displayed above the optical component at a floating distance corresponding to the refractive index of the transparent intermediate layer.

4. The display device according to claim 1, The optical component is a semi-transparent mirror, a beam splitter or a polarizing beam splitter.

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