Airborne display device

Abstract

To provide an aerial display device capable of improving display quality.SOLUTION: An aerial display device includes: a display element 20 for displaying an image; an optical element 40 that is arranged so as to receive light from the display element 20, reflects the light from the display element 20 to an opposite side to the display element 20, and forms an aerial image in the air; a polarization element 50 that is arranged so as to receive light from the optical element 40 and allows linearly polarized light to pass through; and a housing 60 that is configured to surround the optical element 40 and secures the display element 20 and the optical element 40 so as to be spaced apart from each other. A polarization axis of the polarization element 50 is parallel to a polarization axis of the display element 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an aerial display device. [Background technology]

[0002] Aerial display devices capable of displaying images and videos as aerial images are being researched and are expected to be a new human-machine interface. For example, an aerial display device may include a two-sided corner reflector array in which two-sided corner reflectors are arranged in an array, reflecting light emitted from the display surface of a display element and forming a real image in the air. The display method using a two-sided corner reflector array is aberration-free and can display a real image (aerial image) in a plane-symmetrical position.

[0003] Patent Document 1 discloses an optical element in which a transparent rectangular prism protruding from the surface of a transparent flat plate is used as a two-sided corner reflector, and multiple rectangular prisms are arranged in an array on a plane. Patent Document 2 discloses an optical element in which each of the first and second light control panels is formed by arranging multiple planar light reflecting parts perpendicularly inside a transparent flat plate, and the first and second light control panels are arranged so that their planar light reflecting parts are orthogonal to each other. The optical elements of Patent Documents 1 and 2 generate an aerial image by reflecting light emitted from a display element twice on orthogonal reflective surfaces.

[0004] The display devices using optical elements described in Patent Documents 1 and 2 can recognize an aerial image by observing the optical element from an oblique direction, but it is difficult to recognize a good aerial image by observing it from the direction normal to the optical element. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-191404 [Patent Document 2] Japanese Patent Publication No. 2011-175297 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention provides an aerial display device capable of improving display quality. [Means for solving the problem]

[0007] According to a first aspect of the present invention, an aerial display device is provided, comprising: a display element for displaying an image; an optical element positioned to receive light from the display element and reflecting the light from the display element to the opposite side of the display element to form an aerial image in the air; a polarizing element positioned to receive light from the optical element and transmitting linearly polarized light; and a housing configured to surround the optical element and to fix the display element and the optical element with a gap between them, wherein the polarization axis of the polarizing element is parallel to the polarization axis of the display element.

[0008] According to a second aspect of the present invention, an aerial display device according to the first aspect is provided, wherein the housing includes a bottom plate having an opening, and the display element is arranged such that light from the display element passes through the opening.

[0009] According to a third aspect of the present invention, an aerial display device according to the first or second aspect is provided, wherein the optical element includes a planar substrate and a plurality of optical elements provided below the substrate, each extending in a first direction and arranged in a second direction perpendicular to the first direction, and each of the plurality of optical elements is inclined with respect to the normal direction of the substrate and has an incident surface and a reflective surface that are in contact with each other.

[0010] According to a fourth aspect of the present invention, an aerial display device according to any of the first to third aspects is provided, wherein the display element, the optical element, and the polarizing element are arranged parallel to each other.

[0011] According to a fifth aspect of the present invention, an aerial display device according to any one of the first to fourth aspects is provided, further comprising an orientation control element disposed between the display element and the optical element, which transmits a portion of the light from the display element.

[0012] According to the sixth aspect of the present invention, there is provided an aerial display device according to the fifth aspect, wherein the alignment control element includes a plurality of transparent members and a plurality of light shielding members arranged alternately, and the plurality of light shielding members are inclined with respect to the normal direction of the alignment control element.

[0013] According to the seventh aspect of the present invention, there is provided an aerial display device according to the fifth or sixth aspect, wherein the display element and the alignment control element are arranged parallel to each other.

[0014] According to the eighth aspect of the present invention, there is provided an aerial display device according to any one of the first to seventh aspects, further including an illumination element that emits light, wherein the display element is arranged to receive light from the illumination element and is constituted by a liquid crystal display element.

Effects of the Invention

[0015] According to the present invention, it is possible to provide an aerial display device capable of improving display quality.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is an exploded view of an aerial display device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the aerial display device shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view of the aerial display device taken along line A-A' of FIG. 2. [Figure 4] FIG. 4 is a side view of the main part of the aerial display device. [Figure 5] FIG. 5 is a side view of the display element shown in FIG. 1. [Figure 6] FIG. 6 is a cross-sectional view showing the housing extracted. [Figure 7A] FIG. 7A is a plan view of the alignment control element shown in FIG. 1. [Figure 7B] FIG. 7B is a cross-sectional view of the alignment control element taken along line B-B' of FIG. 7A. [Figure 8]Figure 8 is a perspective view of the optical element shown in Figure 1. [Figure 9] Figure 9 is a block diagram of the aerial display device. [Figure 10] Figure 10 is a perspective view illustrating the reflection of light in an optical element. [Figure 11] Figure 11 is a side view of the XZ plane illustrating the reflection of light in an optical element. [Figure 12] Figure 12 is a side view of the YZ plane illustrating the reflection of light in an optical element. [Figure 13] Figure 13 illustrates the angular conditions of the incident and reflective surfaces in an optical element. [Figure 14] Figure 14 is a schematic diagram illustrating the behavior of ambient light. [Figure 15] Figure 15 is a schematic diagram illustrating the behavior of the display light. [Modes for carrying out the invention]

[0017] The embodiments will be described below with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and proportions in each drawing are not necessarily the same as those in reality. Furthermore, even when the same part is represented between drawings, the relationship between dimensions and proportions may be represented differently. In particular, the embodiments shown below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not determined by the shape, structure, arrangement, etc. of the components. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant descriptions are omitted.

[0018] [1] Configuration of the aerial display device 1 Figure 1 is an exploded view of an aerial display device 1 according to an embodiment of the present invention. In Figure 1, the X direction is the direction along one side of the aerial display device 1, the Y direction is the direction perpendicular to the X direction in the horizontal plane, and the Z direction is the direction perpendicular to the XY plane (also called the normal direction). Figure 2 is a plan view of the aerial display device 1 shown in Figure 1. Figure 3 is a cross-sectional view of the aerial display device 1 along line AA' in Figure 2. Figure 4 is a side view of the main part of the aerial display device 1.

[0019] The aerial display device 1 is a device that displays images (including videos). The aerial display device 1 displays an aerial image in the air above its own light-emitting surface. The light-emitting surface of the aerial display device 1 refers to the surface of the uppermost component among the multiple components that make up the aerial display device 1. An aerial image is a real image formed in the air.

[0020] The aerial display device 1 comprises an illumination element (also called a backlight) 10, a display element 20, an orientation control element 30, an optical element 40, a polarizing element 50, and a housing 60. The illumination element 10, the display element 20, the orientation control element 30, the optical element 40, and the polarizing element 50 are arranged in this order along the Z direction and are arranged parallel to each other. The illumination element 10, the display element 20, and the orientation control element 30 are fixed in desired positions by fixing members (not shown) so as to be spaced apart from each other.

[0021] The illumination element 10 emits illumination light and directs this illumination light toward the display element 20. The illumination element 10 comprises a light source unit 11, a light guide plate 12, and a reflective sheet 13. The illumination element 10 is, for example, a side-light type illumination element. The illumination element 10 constitutes a surface light source. The illumination element 10 may be configured so that the light intensity peaks in an oblique direction at an angle θ1, as described later.

[0022] The light source unit 11 is positioned to face the side of the light guide plate 12. The light source unit 11 emits light toward the side of the light guide plate 12. The light source unit 11 includes a plurality of light-emitting elements, such as white LEDs (Light Emitting Diodes). The light guide plate 12 guides the illumination light from the light source unit 11 and emits the illumination light from its upper surface. The reflective sheet 13 reflects the illumination light emitted from the bottom surface of the light guide plate 12 back toward the light guide plate 12. The illumination element 10 may have optical elements (including a prism sheet and a diffusion sheet) on the upper surface of the light guide plate 12 to improve its optical properties.

[0023] The display element 20 is a transmissive display element. The display element 20 is composed of, for example, a liquid crystal display element. The driving mode of the display element 20 is not particularly limited, and TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, or homogeneous mode can be used. The display element 20 receives illumination light emitted from the illumination element 10. The display element 20 transmits the illumination light from the illumination element 10 and performs light modulation. Then, the display element 20 displays a desired image on its display surface.

[0024] Figure 5 is a side view of the display element 20 shown in Figure 1. The display element 20 comprises a liquid crystal panel 20A, a polarizing plate 20B, and a polarizing plate 20C. The liquid crystal panel 20A includes two transparent substrates, a liquid crystal layer sandwiched between the two transparent substrates, and a number of switching elements corresponding to the pixels. A polarizing plate 20B is provided on the illumination element 10 side of the liquid crystal panel 20A, and a polarizing plate 20C is provided on the alignment control element 30 side of the liquid crystal panel 20A.

[0025] Polarizers 20B and 20C are linear polarizers and have a polarization axis. The polarization axis has the same meaning as the transmission axis. Polarizers 20B and 20C transmit linearly polarized light (linearly polarized light component) that has a vibration plane parallel to the polarization axis, among light that has vibration planes in random directions. Polarizers 20B and 20C are arranged, for example, so that their polarization axes are orthogonal to each other, i.e., in a orthogonal nicol state. The relationship of the polarization axes of polarizers 20B and 20C is set appropriately according to the driving mode and the display mode (either normally black or normally white).

[0026] The display element 20 emits display light consisting of linearly polarized light parallel to the polarization axis of the polarizing plate 20C on the top surface. In this embodiment, the polarization axis of the polarizing plate 20C on the top surface is referred to as the polarization axis of the display element 20. As shown in Figure 1, the polarization axis of the display element 20 is set in the Y direction. The display element 20 may be equipped with an optical element on the upper surface of the polarizing plate 20C to improve its optical properties.

[0027] The orientation control element 30 has the function of reducing unwanted light. Unwanted light is light components that do not contribute to the generation of an aerial image and includes light components that are transmitted through the optical element 40 in the normal direction. The orientation control element 30 is configured to block light components outside a predetermined angular range centered on an oblique direction at an angle θ1 with respect to the normal direction. The detailed configuration of the orientation control element 30 will be described later.

[0028] The optical element 40 reflects light incident from the bottom side to the top side. It also reflects incident light obliquely incident from the bottom side, for example, in the front direction (normal direction). The detailed configuration of the optical element 40 will be described later. The optical element 40 forms an aerial image 2 in the air. The aerial image 2 is parallel to the element plane of the optical element 40. The element plane refers to a hypothetical plane extending in the in-plane direction of the optical element 40. The term "element plane" has the same meaning as "in-plane." The same meaning applies to the element planes of other elements. An observer 3, positioned in front of the optical element 40, can see the aerial image 2.

[0029] The polarizing element 50 is a linear polarizer and has a polarization axis. The polarizing element 50 transmits linearly polarized light (linearly polarized light component) that has a vibration plane parallel to the polarization axis, among light that has vibration planes in random directions. The polarization axis of the polarizing element 50 is set in the Y direction. That is, the polarization axis of the polarizing element 50 is set parallel to the polarization axis of the display element 20. The polarizing element 50 may be bonded to the upper surface of the optical element 40 using a transparent adhesive, or it may be placed at a desired distance from the optical element 40. When the optical element 40 and the polarizing element 50 are placed at a desired distance, the polarizing element 50 is fixed by a fixing member (not shown).

[0030] Figure 6 is a cross-sectional view showing the housing 60. The housing 60 has a rectangular box shape. The housing 60 is composed of one bottom plate and four side plates. A rectangular opening 60A is provided in the bottom plate of the housing 60. The opening 60A is for allowing light emitted from the orientation control element 30 to pass through. The laminate consisting of the illumination element 10, the display element 20, and the orientation control element 30 is fixed to the bottom plate of the housing 60 using fixing members (not shown). The orientation control element 30 is exposed through the opening 60A.

[0031] The housing 60 is configured to surround the optical element 40. The housing 60 has a step 60B at its top for fixing the optical element 40. The optical element 40 is fixed to the housing 60 by being placed on the step 60B of the housing 60. The housing 60 has the function of holding the orientation control element 30 and the optical element 40 at a desired distance apart.

[0032] The housing 60 is preferably made of a material capable of reducing light reflection. For example, the housing 60 is made of black resin. Figure 6 shows a magnified view of the inner surface of the housing 60. For example, the inner surface of the housing 60 is roughened. A roughened surface can reduce light reflection.

[0033] [1-1] Configuration of the orientation control element 30 Figure 7A is a plan view of the orientation control element 30 shown in Figure 1. Figure 7B is a cross-sectional view of the orientation control element 30 along the line BB' in Figure 7A.

[0034] The substrate 31 is configured in a rectangular planar shape. The substrate 31 transmits light.

[0035] Multiple transparent members 33 are provided on the base material 31, each extending in the Y direction and aligned in the X direction. Additionally, multiple light-shielding members 34 are provided on the base material 31, each extending in the Y direction and aligned in the X direction. The multiple transparent members 33 and the multiple light-shielding members 34 are arranged alternately so that adjacent members are in contact with each other.

[0036] Multiple transparent members 33 and multiple light-shielding members 34 are provided on a base material 32. The base material 32 is configured in a rectangular planar shape. The base material 32 transmits light.

[0037] The transparent member 33 extends in an oblique direction at an angle θ1 with respect to the normal direction of the base material 31 in the XZ cross-section. The transparent member 33 has a parallelogram shape with its side surface inclined at an angle θ1 in the XZ cross-section. The transparent member 33 transmits light.

[0038] The light-shielding member 34 extends in an oblique direction at an angle θ1 with respect to the normal direction of the base material 31 in the XZ cross-section. The light-shielding member 34 is a parallelogram with its side surface inclined at an angle θ1 in the XZ cross-section. The light-shielding member 34 blocks light.

[0039] The two adjacent light-shielding members 34 are arranged so that their ends slightly overlap in the Z direction.

[0040] A transparent resin is used for the base materials 31, 32, and the transparent member 33, for example, acrylic resin. For the light-shielding member 34, for example, a resin mixed with black dye is used.

[0041] The orientation control element 30 configured in this way can transmit display light such that the light intensity in the oblique direction at an angle θ1 with respect to the normal direction is at its peak. For example, the orientation control element 30 is configured to block light components outside the range of 30°±30° with respect to the normal direction. Preferably, the orientation control element 30 is configured to block light components outside the range of 30°±20° with respect to the normal direction.

[0042] As a modified example, the orientation control element 30 may be placed between the illumination element 10 and the display element 20. Alternatively, the aerial display device 1 may be configured without the orientation control element 30.

[0043] [1-2] Configuration of the optical element 40 Figure 8 is a perspective view of the optical element 40 shown in Figure 1. Figure 8 also shows an enlarged side view of a portion of the optical element 40.

[0044] The optical element 40 comprises a substrate 41 and a plurality of optical elements 42. The substrate 41 is planar in the XY plane and has a rectangular parallelepiped.

[0045] Multiple optical elements 42 are provided on the bottom surface of the base material 41. Each of the multiple optical elements 42 is composed of a triangular prism. The optical elements 42 are arranged such that three sides of the triangular prism are parallel to the XY plane, and one side is in contact with the base material 41. Each of the multiple optical elements 42 extends in the Y direction and is arranged in a line in the X direction. In other words, the multiple optical elements 42 have a sawtooth shape.

[0046] Each of the multiple optical elements 42 has an incident surface 43 and a reflecting surface 44. When viewed from the Y direction, the left side is the incident surface 43 and the right side is the reflecting surface 44. The incident surface 43 is the surface to which light from the display element 20 is incident. The reflecting surface 44 is the surface that reflects light incident on the incident surface 43 from the outside within the optical element 42. The angle between the incident surface 43 and the reflecting surface 44 is θ p It holds.

[0047] The optical element 42 is formed integrally with the base material 41, for example, from the same transparent material as the base material 41. Alternatively, the base material 41 and the optical element 42 may be formed separately, and the optical element 42 may be bonded to the base material 41 using a transparent adhesive. As the transparent material constituting the base material 41 and the optical element 42, for example, acrylic resin or glass can be used.

[0048] The optical element 40 reflects incident light internally to form a real image in the air. Furthermore, the optical element 40 forms a real image at a position directly in front of its surface.

[0049] [1-3] Block configuration of the aerial display device 1 Figure 9 is a block diagram of the aerial display device 1. The aerial display device 1 comprises a control unit 70, a storage unit 71, an input / output interface (input / output IF) 72, a display unit 73, and an input unit 74. The control unit 70, the storage unit 71, and the input / output interface 72 are connected to each other via a bus 75.

[0050] The input / output interface 72 is connected to the display unit 73 and the input unit 74. The input / output interface 72 performs interface processing for each of the display unit 73 and the input unit 74 according to a predetermined standard.

[0051] The display unit 73 includes an illumination element 10 and a display element 20. The display unit 73 displays an image.

[0052] The control unit 70 is composed of one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 70 implements various functions by executing programs stored in the memory unit 71. The control unit 70 includes a display processing unit 70A and an information processing unit 70B.

[0053] The display processing unit 70A controls the operation of the display unit 73 (specifically, the illumination element 10 and the display element 20). The display processing unit 70A controls the on and off of the illumination element 10. The display processing unit 70A transmits an image signal to the display element 20 and causes the display element 20 to display an image.

[0054] The information processing unit 70B generates the image to be displayed by the aerial display device 1. The information processing unit 70B can use the image data stored in the storage unit 71. The information processing unit 70B uses a communication function (not shown) to communicate externally. from You may obtain image data.

[0055] The storage unit 71 includes non-volatile storage devices such as ROM (Read Only Memory), HDD (Hard Disk Drive), and SSD (Solid State Drive), and volatile storage devices such as RAM (Random Access Memory) and registers. The storage unit 71 stores the program executed by the control unit 70. The storage unit 71 stores various data necessary for controlling the control unit 70. The storage unit 71 stores the image data displayed by the aerial display device 1.

[0056] The input unit 74 receives information entered by the user. The information processing unit 70B can select an image to display on the display unit 73 based on the information received by the input unit 74.

[0057] [2] Operation of the aerial display device 1 Next, the operation of the aerial display device 1 configured as described above will be explained.

[0058] [2-1] Display operation The arrows in Figure 4 indicate the optical path. As shown in Figure 4, light emitted from the display element 20 enters the orientation control element 30. Of the light emitted from the display element 20, the optical component at angle θ1 (including the optical component within a predetermined angular range centered on angle θ1) passes through the orientation control element 30. The light that has passed through the orientation control element 30 enters the optical element 40. The optical element 40 images the incident light into the air on the opposite side of the orientation control element 30, displaying an aerial image 2 in the air.

[0059] Figure 10 is a perspective view illustrating the reflection of light in the optical element 40. Figure 11 is a side view of the XZ plane illustrating the reflection of light in the optical element 40. Figure 11 shows the optical element 40 as seen by observer 3 with both eyes (i.e., the line connecting both eyes) parallel to the X direction. Figure 12 is a side view of the YZ plane illustrating the reflection of light in the optical element 40. Figure 12 shows the optical element 40 as seen by observer 3 with both eyes parallel to the Y direction.

[0060] Light emitted from an arbitrary point "o" on the element surface of the orientation control element 30 enters the incident surface 43 of the optical element 40 and reaches the reflection surface 44. Light arriving at an angle greater than the critical angle with respect to the normal direction of the reflection surface 44 is totally reflected by the reflection surface 44 and is emitted from the plane opposite to the side of the optical element 42 of the optical element 40. The critical angle is the smallest angle of incidence beyond which total reflection occurs. The critical angle is the angle with respect to the perpendicular to the incident surface.

[0061] In the XZ plane of Figure 11, light emitted from point "o" is totally reflected by the reflective surface 44 of the optical element 42, and the light is imaged in the air to generate an aerial image.

[0062] In the YZ plane of Figure 12, the light emitted from point "o" is not reflected by the reflective surface 44 of the optical element 42, and therefore does not form an image in the air, thus not contributing to the generation of an aerial image.

[0063] That is, the condition for the observer 3 to recognize the aerial image is that both eyes of the observer 3 are parallel to the X direction or in a state close thereto (for example, ±10 degrees with respect to the X direction). Further, when the observer 3 moves the viewpoint along the Y direction with both eyes parallel to the X direction or in a state close thereto, the aerial image can always be recognized.

[0064] FIG. 13 is a diagram for explaining the angular conditions of the incident surface 43 and the reflection surface 44 in the optical element 40.

[0065] Let the angle of the incident surface 43 with respect to the Z direction (direction perpendicular to the element surface) be θ2, the angle of the reflection surface 44 with respect to the Z direction be θ3, and the angle formed by the incident surface 43 and the reflection surface 44 be θ p be. angle θ p is represented by the following formula (1). θ p = θ2 + θ3 ··· (1) The light emitted from the display element 20 at an angle θ1 is incident on the incident surface 43. Let the refractive index of the material of the optical element 40 be n p , and the refractive index of air be 1. Let the incident angle on the incident surface 43 be θ4 and the refraction angle be θ5. Let the incident angle on the reflection surface 44 be θ6 and the reflection angle be θ7 (= θ6). Let the incident angle on the upper surface of the optical element 40 be θ8 and the refraction angle be θ9. The refraction angle θ9 is the exit angle. The exit angle θ9 is represented by the following formula (2). θ9 = sin -1 (n p * sin (sin -1 ((1 / n p ) * sin (90° - (θ1 + θ2)) + θ2 + 2θ3 - 90°)) ··· (2) The critical angle on the reflection surface 44 is represented by the following formula (3). Critical angle < θ6 (= θ7) Critical angle = sin -1 (1 / n p ) ··· (3) That is, the incident angle θ6 on the reflection surface 44 is set to be larger than the critical angle on the reflection surface 44. In other words, the angle θ3 of the reflection surface 44 is set such that the incident angle of the light incident on the reflection surface 44 is larger than the critical angle.

[0066] Furthermore, the light incident on the incident surface 43 is set so that it is not totally reflected at the incident surface 43. In other words, the angle θ2 of the incident surface 43 is set so that the angle of incidence of the light incident on the incident surface 43 is smaller than the critical angle.

[0067] [2-2] Detailed operation regarding polarization Next, we will describe the detailed operation of the aerial display device 1 regarding polarization.

[0068] External light enters the aerial display device 1. External light is light that enters the aerial display device 1 from outside the device. External light includes sunlight and light from indoor lighting fixtures. The plane of vibration of the external light, and the amplitude, phase, and frequency within that plane, are distributed haphazardly in all directions. External light is unpolarized natural light.

[0069] Figure 14 is a schematic diagram illustrating the behavior of ambient light. Figure 14 shows an exploded view of the aerial display device 1. In Figure 14, one side of the aerial display device 1 is omitted to facilitate understanding of the schematic diagram. The thick arrows in Figure 14 represent the behavior of light. The double-headed arrows in Figure 14 represent the polarization direction.

[0070] Let's focus on ambient light incident from an oblique angle opposite to the direction in which the light-shielding member 34 is tilted with respect to the normal direction of the element surface of the orientation control element 30, that is, ambient light incident from the upper left of the aerial display device 1. This ambient light is incident on the polarizing element 50 from above the aerial display device 1. Of the ambient light incident on the polarizing element 50, the light component parallel to the polarization axis of the polarizing element 50 (linearly polarized light) is transmitted through the polarizing element 50, and the other light components are absorbed by the polarizing element 50. The light components transmitted through the polarizing element 50 reach the orientation control element 30. The light components that reach the orientation control element 30 (point "A") are irradiated onto the light-shielding member 34 of the orientation control element 30 and absorbed by the light-shielding member 34. Therefore, the linearly polarized light transmitted through the polarizing element 50 is not reflected by the orientation control element 30.

[0071] The light component that passes through the polarizing element 50 also reaches the bottom plate of the housing 60. The light component that reaches the bottom plate of the housing 60 (point "B") is diffusely reflected due to the rough surface of the housing 60. Diffuse reflection means that light is reflected in various directions by the reflective surface. The light component diffusely reflected by the bottom plate of the housing 60 becomes unpolarized.

[0072] The light component diffusely reflected by the bottom plate of the housing 60 passes through the optical element 40 and is reflected in the Z direction, and then enters the polarizing element 50. Of the light incident on the polarizing element 50, the light component parallel to the polarization axis of the polarizing element 50 (linearly polarized light) passes through the polarizing element 50, while the other light components are absorbed by the polarizing element 50. The light component that has passed through the polarizing element 50 is emitted from the aerial display device 1 toward the observer.

[0073] We focus on the light component of the ambient light incident on the aerial display device 1 that is reflected by the bottom plate of the housing 60. We assume that the transmittance of the polarizing element 50 in the unpolarized state is 50%, and the reflectance of the housing 60 is 10%. In this case, the light component emitted from the aerial display device 1 can be reduced to 2.5% of the ambient light incident on the aerial display device 1.

[0074] Next, the behavior of the display light emitted from the display element 20 will be explained. Figure 15 is a schematic diagram illustrating the behavior of the display light. The thick arrows in Figure 15 represent the characteristics of the light. The double-headed arrows in Figure 15 represent the polarization direction.

[0075] The display light emitted from the display element 20 consists of linearly polarized light parallel to the polarization axis of the display element 20. The display light emitted from the display element 20 passes through the orientation control element 30. The light component that has passed through the orientation control element 30 passes through the optical element 40 and is reflected in the Z direction, and is incident on the polarizing element 50. The polarization axis of the display element 20 and the polarization axis of the polarizing element 50 are set parallel to each other. The light component incident on the polarizing element 50 passes through the polarizing element 50 with almost no decrease in light intensity. The light component that has passed through the polarizing element 50 is emitted from the aerial display device 1 toward the observer.

[0076] The transmittance of the polarizing element 50 in linearly polarized light parallel to the polarization axis of the polarizing element 50 is assumed to be 100%. In this case, the transmittance of the display light emitted from the display element 20 is, in principle, 100%.

[0077] [3] Effects of the embodiment According to an embodiment of the present invention, an aerial image can be displayed in the air by reflecting light emitted from the display element 20 with the optical element 40. Furthermore, an aerial image can be displayed in the direction in front of the aerial display device 1.

[0078] Furthermore, ambient light incident on the aerial display device 1 and reflected by the housing 60 passes through the polarizing element 50 twice. This reduces the intensity of ambient light emitted from the aerial display device 1. In other words, it reduces unwanted light components that do not contribute to the display of the aerial image.

[0079] Furthermore, the housing 60 is made of black resin, and the inner surface of the housing 60 is roughened. Therefore, the light component diffusely reflected by the housing 60 can be reduced. As a result, the intensity of ambient light emitted from the aerial display device 1 can be reduced.

[0080] Furthermore, a portion of the ambient light that passes through the polarizing element 50 is absorbed by the light-shielding member 34 of the orientation control element 30. In other words, it is possible to prevent a portion of the ambient light incident on the orientation control element 30 from being reflected back towards the observer. This improves the display quality of the aerial display device 1.

[0081] Furthermore, the display light emitted from the display element 20 passes through the polarizing element 50 almost unchanged. Therefore, the decrease in the light intensity of the display light emitted from the display element 20 can be suppressed. This makes it possible to realize an aerial display device 1 that can improve display quality.

[0082] Furthermore, when observer 3 views the optical element 40 with both eyes parallel to or nearly parallel to the X direction (i.e., the direction in which the multiple optical elements 42 are aligned), observer 3 can perceive the aerial image. Also, when observer 3 moves their viewpoint along the Y direction with both eyes parallel to or nearly parallel to the X direction, they can always perceive the aerial image. In other words, a field of view can be secured when both eyes of observer 3 are parallel to or nearly parallel to the X direction.

[0083] Furthermore, multiple elements constituting the aerial display device 1 can be arranged in parallel. This makes it possible to realize an aerial display device 1 that can be miniaturized in the Z direction.

[0084] In the above embodiment, the display element 20 and the optical element 40 are arranged in parallel. However, the embodiment is not limited to this, and the display element 20 may be arranged diagonally with respect to the optical element 40. The angle between the display element 20 and the optical element 40 is set to a range greater than 0 degrees and less than 45 degrees.

[0085] In the above embodiment, the left side of the optical element 42 is defined as the incident surface 43, and the right side is defined as the reflective surface 44. However, the embodiment is not limited to this, and the incident surface 43 and the reflective surface 44 may be configured in reverse. In this case, the operation of the aerial display device 1 described in the embodiment will also be reversed left and right.

[0086] In the above embodiment, a liquid crystal display element is used as an example for the display element 20, but it is not limited to this. The display element 20 can also be a self-emissive organic EL (electroluminescence) display element or a micro-LED (light-emitting diode) display element. A micro-LED display element is a display element that emits R (red), G (green), and B (blue) light, which constitute the pixels, using LEDs. When a self-emissive display element 20 is used, the illumination element 10 is not required.

[0087] The present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of Symbols]

[0088] 1...Aerial display device, 2...Aerial image, 3...Observer, 10...Illumination element, 11...Light source unit, 12...Light guide plate, 13...Reflective sheet, 20...Display element, 20A...Liquid crystal panel, 20B,20C...Polarizing plate, 30...Orientation control element, 31,32...Substrate, 33...Transparent member, 34...Light shielding member, 40...Optical element, 41...Substrate, 42...Optical element, 43...Incident surface, 44...Reflective surface, 50...Polarizing element, 60...Housing, 60A...Opening, 60B...Step, 70...Control unit, 70A...Display processing unit, 70B...Information processing unit, 71...Storage unit, 72...Input / output interface, 73...Display unit, 74...Input unit, 75...Bus.

Claims

1. A display element that displays an image, An optical element is positioned to receive light from the display element, and reflects the light from the display element to the opposite side of the display element, forming an aerial image in the air. A polarizing element is arranged to receive light from the aforementioned optical element and transmits linearly polarized light, A housing is configured to surround the optical element and to fix the display element and the optical element with a gap between them, It is equipped with, The polarization axis of the polarizing element is parallel to the polarization axis of the display element. The housing includes a bottom plate having an opening, The display element is arranged such that light from the display element passes through the opening. Aerial display device.

2. The optical element includes a planar substrate and a plurality of optical elements provided beneath the substrate, each extending in a first direction and arranged in a second direction perpendicular to the first direction. Each of the plurality of optical elements is inclined with respect to the normal direction of the substrate and has an incident surface and a reflective surface that are in contact with each other. The aerial display device according to claim 1.

3. The display element, the optical element, and the polarizing element are arranged parallel to each other. The aerial display device according to claim 1 or 2.

4. The system further comprises an orientation control element disposed between the display element and the optical element, which transmits a portion of the light from the display element. The aerial display device according to any one of claims 1 to 3.

5. The orientation control element includes a plurality of transparent members and a plurality of light-shielding members arranged alternately. The plurality of light-shielding members are inclined with respect to the direction normal to the orientation control element. The aerial display device according to claim 4.

6. The display element and the orientation control element are arranged parallel to each other. The aerial display device according to claim 4 or 5.

7. It further comprises a light-generating illuminating element, The display element is arranged to receive light from the illumination element and is composed of a liquid crystal display element. The aerial display device according to any one of claims 1 to 6.

Images