Display device

Abstract

The invention provides a display device which suppresses stray light and improves visibility and contrast of an aerial image. This aerial image display device (100) is provided with: a beam splitter (110); a retroreflective sheet (120) which is disposed so as to face the beam splitter (110) and in which a cutout or an opening for generating a pattern (Q) of an original image of the aerial image is formed; a transparent member (e.g., acrylic acid) (130) disposed between the beam splitter (110) and the retroreflective sheet (120); and a light source (140) that irradiates the retroreflective sheet (120) from the rear surface side. The aerial image (P) of the pattern (Q) irradiated by the light source (140) is displayed above the beam splitter (110) while floating.

Description

Technical Field

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

[0002] Aerial Imaging by Retro-Reflection (AIRR) is known. For example, Patent Document 1 discloses a display device including a semi-transparent mirror, an image output device that outputs light toward one side of the semi-transparent mirror, and a retro-reflective component that is disposed between the image output device and the semi-transparent mirror and has a plurality of openings. In addition, Patent Document 2 discloses an aerial display device including: a planar light-emitting body having a light-emitting portion; a retro-reflective sheet disposed on the emission surface side of the planar light-emitting body and having a plurality of through holes representing a graphic to be displayed in the air at a position corresponding to the light-emitting portion; and a semi-transparent mirror disposed on the emission surface side of the retro-reflective sheet.

[0003] [Prior art literature]

[0004] [Patent Document]

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

[0006] [Patent Document 2] Japanese Patent Application Publication No. 2022-140264 Summary of the invention

[0007] As an AIRR-type aerial display system, there is a system that uses LED as a light source to display a fixed display pattern in the air. In order to achieve miniaturization and thinness, such a display device is arranged in a manner in which each optical component faces each other. Figure 1 A structural example thereof is shown in FIG.

[0008] Figure 1 (A) is a schematic stereoscopic diagram of a conventional aerial image display device. Figure 1 (B) is a schematic cross-sectional view thereof. The aerial image display device 10 includes, for example, a beam splitter 30 disposed on the surface of a rectangular housing 20; a retroreflective sheet 40 disposed inside the housing 20 in a manner opposite to the beam splitter 30; and a light source 50 such as an LED disposed on the back side of the retroreflective sheet 40.

[0009] The retroreflective sheet 40 is an optical member or optical element that reflects light in the same direction as the incident light, and has cutouts or openings S. The cutouts or openings S generate a pattern (fixed display pattern) Q that becomes an original image of the aerial image P. Figure 1 The aerial image P in (A) shows, for example, an icon indicating the rewind direction of playback.

[0010] When the retroreflective sheeting 40 is irradiated from the back side by the light source 50 , the light having passed through the slit S is retroreflected between the retroreflective sheeting 40 and the beam splitter 30 , and an aerial image P of the pattern Q is displayed above the beam splitter 30 .

[0011] However, the conventional aerial image display device 10 has the following problems. Figure 2 (A) is a diagram illustrating the cross-sectional structure of the retroreflective sheet 40 and the surface reflection of the retroreflective sheet 40 and the internal surface reflection generated inside. The retroreflective sheet 40 is configured to include: a pattern forming portion 42 formed of a light-transmitting material, a metal layer 44 (such as Al, etc.) formed on the inclined surface of the pattern forming portion 42, an optical adhesive 46 applied to the upper surface of the pattern forming portion 42, and a phase plate (such as a λ / 4 plate) 48 attached to the optical adhesive 46. The metal layer 44 functions as a reflective layer, and the thickness including the optical adhesive 46 and the phase plate 48 is, for example, 1 mm or less.

[0012] Light L1: Light incident on the retroreflective sheet 40 is reflected multiple times by the metal layer 44, and the reflected light is reflected in the same direction as the incident light. Such light L1 is light that conforms to the optical characteristics of the retroreflective sheet 40 and is desired light.

[0013] Light L2: A portion of the light incident on the retroreflective sheet 40 is reflected by the surface of the phase plate 48, and the reflected light is regularly reflected at a reflection angle equal to the incident angle. Such light L2 does not conform to the optical characteristics of the retroreflective sheet 40 and is undesirable light.

[0014] Light L3: A portion of the light incident on the retroreflective sheet 40 is reflected by the metal layer 44, then is internally reflected by the phase plate 48, and is reflected again by the metal layer 44. Such light L3 is a light having a large optical path difference between the incident light and the reflected light and does not conform to the optical characteristics of the retroreflective sheet 40, and is undesirable light.

[0015] When the unwanted light L2, L3 is generated by the retro-reflective sheet 40, as shown in FIG. Figure 2 As shown in (B), stray light (or virtual image) V of pattern Q is generated, and a pseudo aerial image W caused by the stray light (or virtual image) V is generated. As a result, Figure 3 As shown in (A) and (B) of FIG. 1 , within the range where the user observes the aerial image P, a plurality of virtual images V and pseudo aerial images W are reflected in the periphery thereof, and the visibility and contrast of the aerial image P are reduced.

[0016] An object of the present invention is to solve such conventional technical problems and to provide a display device that suppresses stray light or false aerial images and improves the visibility and contrast of aerial images.

[0017] The display device of the present invention can utilize retroreflection to display an aerial image, and the display device includes: an optical component that separates incident light into reflected light and transmitted light; a retroreflective component that is opposite to the optical component and has a pattern formed by a notch or an opening; a light source that is disposed on the back side of the retroreflective component; and a transparent component that is disposed between the optical component and the retroreflective component and is composed of a material with a refractive index greater than 1.

[0018] In one embodiment, the transparent component has a substantially rectangular shape, the upper surface of the transparent component contacts the optical component, and the bottom surface contacts the retro-reflective component. In one embodiment, the transparent component is made of a material whose refractive index difference with the retro-reflective component is substantially zero or below a certain value. In one embodiment, when the retro-reflective component includes a phase component on the surface, the transparent component is made of a material whose refractive index difference with the phase component is substantially zero or below a certain value. In one embodiment, the transparent component is made of an acrylic material. In one embodiment, the optical component is a semi-transparent mirror, a beam splitter, or a polarizing beam splitter.

[0019] [Effects of the invention]

[0020] According to the present invention, by arranging a transparent component with a refractive index greater than 1 between the optical component and the retroreflective component, the refractive index difference between the transparent component and the retroreflective component can be reduced, and reflection at the interface between the transparent component and the retroreflective component can be suppressed. Thus, the generation of stray light and false aerial images can be suppressed, and the visual recognition and contrast of the aerial image can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (A) is a stereoscopic diagram of a conventional aerial image display device. Figure 1 (B) is a schematic cross-sectional view thereof.

[0022] Figure 2 (A) is a diagram illustrating the cross-sectional structure of the retroreflective sheet and the surface reflection and internal surface reflection of the retroreflective sheet. Figure 2 (B) is a diagram for explaining the generation of stray light (virtual image) and a pseudo aerial image in a conventional aerial image display device.

[0023] Figure 3 FIG. 1 is a diagram schematically showing an aerial image and a pseudo aerial image in a conventional aerial image display device.

[0024] Figure 4 (A) is a schematic cross-sectional view of an aerial image display device according to an embodiment of the present invention, Figure 4 (B) is a diagram for explaining the generation of an aerial image in the aerial image display device of this embodiment. DETAILED DESCRIPTION

[0025] The display device of the present invention displays an aerial image using retroreflection in three-dimensional space even without wearing special glasses, etc. It should be noted that the drawings referred to in the following description of the embodiments include exaggerated displays for easy understanding of the invention and do not directly represent the shape and size of the actual product.

[0026] [Example]

[0027] Next, embodiments of the present invention will be described in detail. Figure 4 (A) is a schematic cross-sectional view of an aerial image display device according to an embodiment of the present invention, Figure 4 (B) is a diagram for explaining the generation of an aerial image. The aerial image display device 100 of this embodiment is configured to include, for example: a beam splitter 110 disposed on the surface of a rectangular housing or frame; a retro-reflective sheet 120 disposed opposite to the beam splitter 110; a transparent member 130 having a refractive index greater than 1 disposed between the beam splitter 110 and the retro-reflective sheet 120; and a light source 140 disposed on the back side of the retro-reflective sheet 120.

[0028] The beam splitter 110 is an optical component or an optical element that separates incident light into reflected light and transmitted light. The beam splitter 110 uses, for example, a half mirror, and when using polarized light, a polarizing beam splitter is used.

[0029] The retroreflective sheet 120 is arranged to face the beam splitter 120. The retroreflective sheet 130 is an optical component or optical element that reflects light in the same direction as the incident light, and is composed of, for example, a prism-type retroreflective element such as a triangular pyramid-type retroreflective element, a full-cube corner retroreflective element, or a bead-type retroreflective element. Figure 2 The retroreflective sheet 40 shown in (A) is similarly configured, that is, it has a pattern forming portion 42 formed of a light-transmitting material, a metal layer 44 formed on the inclined surface of the pattern forming portion 42, an optical adhesive 46 applied to the upper surface of the pattern forming portion 42, and a phase plate (e.g., a λ / 4 plate) 48 attached to the optical adhesive 46. However, the retroreflective sheet 120 is not limited to such a structure, and it is also possible not to have a phase plate 48 on the surface.

[0030] The shape and size of the retro-reflective sheet 120 are not particularly limited, and a notch or opening for generating a pattern Q of an original image that becomes the aerial image P is formed in the retro-reflective sheet 120. Figure 1 As shown in (A), the pattern Q is an icon indicating the reverse direction of reproduction. However, the type (characters, icons, etc.) and number of patterns formed on the retroreflective sheet 120 are arbitrary.

[0031] A light source 140 is arranged on the back side of the retroreflective sheet 120. The light source 140 is not particularly limited, and may be, for example, an LED light source, a display light source such as a liquid crystal, a projection light source such as a projector, etc. In the case of using an LED light source, for example, a plurality of LEDs may be arranged in a linear or planar shape, and the entire back side of the retroreflective sheet 120 may be efficiently and completely irradiated. In a certain embodiment, a diffuser and a diffuser may be used together to uniformly irradiate the back side of the retroreflective sheet 120. Furthermore, the light source 140 may also be arranged to include a polarizing plate or a polarizing film, and the back side of the retroreflective sheet 120 may be irradiated with polarized light. In this case, a polarizing beam splitter is used as the beam splitter 110, a λ / 4 film is provided on the surface of the retroreflective sheet 120, and the polarization state of the polarizing plate or the polarizing film is determined in relation to the polarization state of the polarizing beam splitter.

[0032] A light-transmitting transparent member 130 having a refractive index greater than 1 is disposed between the beam splitter 110 and the retroreflective sheet 120. Preferably, the transparent member 130 is made of a material having a refractive index similar to that of the retroreflective sheet 120, and the difference in refractive index between the transparent member 130 and the retroreflective sheet 120 is infinitely reduced. In the case where a phase plate 48 is formed on the surface of the retroreflective sheet 120, a material having a refractive index similar to that of the phase plate 48 is selected. The similar refractive index means that the difference in refractive index between the two is infinitely small. For example, in the case of forming a λ / 4 plate (or a λ / 4 film), if the refractive index of the λ / 4 plate is about 1.5, an acrylic material is selected as a material having a refractive index of about 1.5 in the transparent member 130. In addition, in addition to using an acrylic material, the transparent member 130 can also use other plastic materials (for example, PC (refractive index 1.584, polystyrene (refractive index 1.592), PET (refractive index 1.576)) according to the refractive index of the retroreflective sheet 120 and the phase plate 48.

[0033] The transparent member 130 has a substantially rectangular shape, and has a beam splitter 110 formed on its upper surface and a retro-reflective sheet 120 formed on its back surface. The beam splitter 110 may be formed as a film on the upper surface of the transparent member 130, or may be attached by an optical adhesive. In addition, the retro-reflective sheet 120 may also be attached to the back surface of the transparent member 120 by, for example, an optical adhesive.

[0034] Next, the operation of the aerial image display device 100 of this embodiment will be described. Figure 4As shown in (B), light from the light source 140 irradiates the back side of the retroreflective sheet 120, and the irradiated light passes through the cutout or opening formed in the retroreflective sheet 120 to generate a pattern Q as the original image of the aerial image P. The light that passes through the cutout or opening is partially reflected by the beam splitter 110 via the transparent member 130, and the reflected light is retroreflected by the retroreflective sheet 120. The retroreflected light passes through the beam splitter 110 via the transparent member 130, and the aerial image Q of the pattern P is formed above the beam splitter 110.

[0035] By embedding a transparent member 130 having a refractive index greater than 1 between the beam splitter 110 and the retroreflective sheet 120, the difference in refractive index between the transparent member 130 and the retroreflective sheet 120 can be minimized compared to when the space is an air layer, and regular reflection of light incident on and emitted from the retroreflective sheet 120 on the surface of the retroreflective sheet 120 and internal surface reflection generated inside the sheet can be reduced. Ideally, if the refractive index of the transparent member 130 and the retroreflective sheet 120 is equal, the transparent member 130 and the retroreflective sheet 120 can be regarded as the same optically seamless member. Therefore, it is possible to suppress the occurrence of optical problems such as Figure 2 The unwanted light L2 and L3 shown in (A) and (B) caused by the reflection generated on the surface of the retroreflective sheet 120 can suppress the generation of the virtual image and stray light V of the pattern Q. As a result, the generation of the pseudo aerial image W can be suppressed and the visual recognizability and contrast of the aerial image P can be improved.

[0036] Furthermore, by interposing the transparent member 130 having a refractive index greater than 1, the refraction angle of the light passing through the beam splitter 110 becomes larger than that in the air layer, and the floating distance of the aerial image P becomes slightly smaller. Therefore, when displaying an aerial image with a large floating distance, the thickness of the transparent member 130 needs to be considered.

[0037] The aerial image display device of this embodiment can be applied to the display of information and user input of all devices, for example, it can be applied to computer devices, vehicle-mounted electronic devices, ATMs in banks, ticket purchasing machines in stations, etc., input buttons in elevators, etc.

[0038] As mentioned above, although the preferred embodiment of the present invention is described in detail, the present invention is not limited to the specific embodiment, and various modifications and changes can be made within the scope of the gist of the invention described in the claims.

[0039] [Explanation of Reference Numerals]

[0040] 100: Aerial image display device

[0041] 110: Beam splitter

[0042] 120: Retro-reflective sheet

[0043] 130: Transparent parts

[0044] 140: Light source

[0045] P: Aerial Image

[0046] Q: Pattern (original image)

Claims

1. A display device capable of displaying an aerial image by utilizing retro-reflection, the display device comprising: Optical components that separate incident light into reflected light and transmitted light; A retro-reflective component, which is opposite to the optical component and has a pattern formed by a notch or an opening; A light source is disposed on the back side of the retro-reflective component; as well as The transparent component is disposed between the optical component and the retro-reflective component and is made of a material having a refractive index greater than 1.

2. The display device according to claim 1, The transparent member has a substantially rectangular shape, and an upper surface of the transparent member is in contact with the optical member, and a bottom surface of the transparent member is in contact with the retro-reflective member.

3. The display device according to claim 1, The transparent member is made of a material whose refractive index difference with the retroreflective member is substantially zero or equal to or less than a certain value.

4. The display device according to claim 1, When the retroreflective member includes a phase member on the surface, the transparent member is made of a material having a refractive index difference with the phase member of substantially zero or a certain value or less.

5. The display device according to claim 1, The transparent member is made of acrylic material.

6. 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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