JP2024047999A - Aerial Display Device - Google Patents

Abstract

[Problem] To provide an aerial display device capable of improving display quality. [Solution] The aerial display device includes a display element 20 that displays an image, an optical element 50 that is arranged to receive light from the display element 20 and reflects the light from the display element 20 to the opposite side of the display element 20 to form an aerial image in the air, and a housing 60 that is configured to surround the periphery of the optical element 50 and fixes the optical element 50. The area of the element arranged opposite the optical element 50 is larger than the area of the optical element 50. [Selected Figure] Figure 1

Description

The present invention relates to an aerial display device.

Aerial display devices capable of displaying images and videos as aerial images are being researched, and are expected to become a new human-machine interface. For example, an aerial display device may be equipped with a two-sided corner reflector array in which two-sided corner reflectors are arranged in an array, and it reflects light emitted from the display surface of a display element to form 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.

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 dihedral corner reflector, and multiple rectangular prisms are arranged in an array on a flat surface. 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 sections vertically inside a transparent flat plate, and the first and second light control panels are arranged so that the planar light reflecting sections are orthogonal to each other. The optical elements of Patent Documents 1 and 2 reflect light emitted from a display element twice at orthogonal reflecting surfaces to generate an aerial image.

The display devices using the optical elements of Patent Documents 1 and 2 are capable of recognizing an aerial image by observing the optical element from an oblique direction, and it is difficult to recognize a good aerial image by observing the optical element from the normal direction.

JP 2011-191404 A JP 2011-175297 A

The present invention provides an aerial display device that can improve display quality.

According to a first aspect of the present invention, there is provided an aerial display device comprising: a display element for displaying an image; an optical element arranged to receive light from the display element and reflect the light from the display element to the opposite side of the display element to form an aerial image in the air; and a housing arranged to surround the periphery of the optical element and to fix the optical element, the area of the element arranged opposite the optical element being larger than the area of the optical element.

According to a second aspect of the present invention, there is provided an aerial display device according to the first aspect, further comprising an orientation control element disposed between the display element and the optical element, which transmits oblique light components of the light from the display element, and the area of the orientation control element is larger than the area of the optical element.

According to a third aspect of the present invention, there is provided an aerial display device according to the second aspect, in which the outer periphery of the orientation control element extends to the housing.

According to a fourth aspect of the present invention, there is provided an aerial display device according to the second aspect, further comprising a light absorbing layer that is provided on the bottom surface of the alignment control element, has an opening through which light from the display element passes, and absorbs light.

According to a fifth aspect of the present invention, there is provided an aerial display device according to the fourth aspect, in which the outer periphery of the light absorbing layer extends to the outer periphery of the alignment control element.

According to a sixth aspect of the present invention, there is provided an aerial display device according to the second aspect, in which the alignment control element includes a plurality of transparent members and a plurality of light blocking members arranged alternately, and the plurality of light blocking members are inclined with respect to the normal direction of the alignment control element.

According to a seventh aspect of the present invention, there is provided an aerial display device according to the second aspect, further comprising an anti-reflection layer provided on the upper surface of the alignment control element.

According to an eighth aspect of the present invention, there is provided an aerial display device according to the first aspect, further comprising a transparent support member disposed between the display element and the optical element, the area of the support member being larger than the area of the optical element.

According to a ninth aspect of the present invention, there is provided an aerial display device according to the eighth aspect, in which the outer periphery of the support member extends to the housing.

According to a tenth aspect of the present invention, there is provided an aerial display device according to the eighth aspect, further comprising a light absorbing layer that is provided on the bottom surface of the support member, has an opening through which light from the display element passes, and absorbs light.

According to an eleventh aspect of the present invention, there is provided an aerial display device according to the tenth aspect, in which the outer periphery of the light absorbing layer extends to the outer periphery of the support member.

According to a twelfth aspect of the present invention, there is provided an aerial display device according to the eighth aspect, further comprising an anti-reflection layer provided on the upper surface of the support member.

According to a thirteenth aspect of the present invention, there is provided an aerial display device according to the first aspect, in which the optical element includes a planar substrate and a plurality of optical elements disposed below the substrate, each extending in a first direction and aligned in a second direction perpendicular to the first direction, each of the plurality of optical elements being inclined with respect to the normal direction of the substrate and having an entrance surface and a reflection surface that are in contact with each other.

According to a fourteenth aspect of the present invention, there is provided an aerial display device according to the first aspect, in which the display element and the optical element are arranged parallel to each other.

The present invention provides an aerial display device that can improve display quality.

FIG. 1 is an exploded view of an aerial display device according to a first embodiment of the present invention. FIG. 2 is a plan view of the aerial display device shown in FIG. FIG. 3 is a cross-sectional view of the aerial display device taken along line AA' in FIG. FIG. 4 is a schematic side view illustrating the optical path of the aerial display device. FIG. 5A is a plan view of the alignment control element shown in FIG. FIG. 5B is a cross-sectional view of the alignment control element taken along line BB' in FIG. 5A. FIG. 6 is a schematic cross-sectional view illustrating the area of an alignment control element. FIG. 7 is a perspective view of the optical element shown in FIG. FIG. 8 is a block diagram of an aerial display device. FIG. 9 is a perspective view illustrating the state of light reflection in an optical element. FIG. 10 is a side view of the XZ plane for explaining how light is reflected in the optical element. FIG. 11 is a side view of the YZ plane for explaining how light is reflected in the optical element. FIG. 12 is a diagram for explaining the angular conditions of the incident surface and the reflecting surface in the optical element. FIG. 13 is a diagram illustrating the state of external light entering the aerial display device. FIG. 14 is a cross-sectional view of an aerial display device 1 according to a modified example. FIG. 15 is an exploded view of an aerial display device according to a comparative example. FIG. 16 is a partial cross-sectional view taken along the X direction of an aerial display device according to a comparative example. FIG. 17 is a diagram illustrating the state of external light entering the aerial display device. FIG. 18 is a diagram for explaining a display element image and an aerial image. FIG. 19 is a cross-sectional view taken along the X direction of the aerial display device according to the second embodiment of the present invention. FIG. 20 is a diagram illustrating the state of light reflected inside the aerial display device. FIG. 21 is an exploded view of an aerial display device according to the third embodiment of the present invention. FIG. 22 is a cross-sectional view taken along the X direction of the aerial display device shown in FIG. FIG. 23 is a diagram illustrating the state of external light entering an aerial display device. FIG. 24 is a cross-sectional view of an aerial display device 1 according to a modified example.

The following describes the embodiments with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as those in reality. Even when the same parts are shown in different drawings, the dimensional relationships and ratios of each may be different. In particular, the following embodiments are examples of devices and methods for embodying the technical idea of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical idea of the present invention. In the following description, elements having the same function and configuration are given the same reference numerals, and duplicate descriptions are omitted.

[1] First embodiment [1-1] Configuration of the aerial display device 1 Fig. 1 is an exploded view of the aerial display device 1 according to the first embodiment of the present invention. In Fig. 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). Fig. 2 is a plan view of the aerial display device 1 shown in Fig. 1. Fig. 3 is a cross-sectional view of the aerial display device 1 taken along line A-A' in Fig. 2. Fig. 4 is a schematic side view illustrating the optical path of the aerial display device 1.

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 emission surface. The light emission surface of the aerial display device 1 refers to the upper surface of the component that is arranged in the uppermost layer among the multiple components that make up the aerial display device 1. The aerial image is a real image that is formed in the air.

The aerial display device 1 comprises an illumination element (also called a backlight) 10, a display element 20, a light absorption layer 30, an orientation control element 40, an optical element 50, and a housing 60. The illumination element 10, the display element 20, the light absorption layer 30, the orientation control element 40, and the optical element 50 are arranged in this order along the Z direction and parallel to one another. The illumination element 10, the display element 20, and the orientation control element 40 are fixed at desired positions with a fixing member (not shown) so as to leave a desired distance between each other.

The lighting element 10 emits illumination light and outputs the illumination light toward the display element 20. The lighting element 10 includes a light source unit 11, a light guide plate 12, and a reflective sheet 13. The lighting element 10 is, for example, a side light type lighting element. The lighting element 10 constitutes a surface light source. The lighting element 10 may be configured so that the light intensity reaches a peak in an oblique direction at an angle _θ1 , which will be described later.

The light source unit 11 is disposed 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, for example, 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 reflection 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 lighting element 10 may be provided with a member (including a prism sheet and a diffusion sheet) that improves optical characteristics on the upper surface of the light guide plate 12.

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 the TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, homogeneous mode, or the like 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 optical modulation. Then, the display element 20 displays a desired image on its display surface.

The light absorbing layer 30 has a function of absorbing light and blocking light. The light absorbing layer 30 has a rectangular opening 31. The opening 31 has approximately the same area as the display surface of the display element 20 and exposes the display surface of the display element 20. The outer periphery of the light absorbing layer 30 extends to the outer periphery of the alignment control element 40. The light absorbing layer 30 is made of, for example, a resin mixed with a black dye or pigment. The light absorbing layer 30 is formed in a film shape and is attached to the bottom surface of the alignment control element 40 using a transparent adhesive. The light absorbing layer 30 is attached to the outer periphery of the display element 20 using a transparent adhesive. The light absorbing layer 30 is made of black paint, and may be formed by applying this black paint to the bottom surface of the alignment control element 40.

The orientation control element 40 has a function of reducing unnecessary light. The unnecessary light is a light component that does not contribute to generating an aerial image, and includes a light component that transmits through the optical element 50 in the normal direction. The orientation control element 40 is configured to transmit light components in a predetermined angular range centered on an oblique direction at an angle θ ₁ with respect to the normal direction, and to block light components outside the above-mentioned angular range. A detailed configuration of the orientation control element 40 will be described later.

The area of the alignment control element 40 is larger than the area of the display element 20. The length of the alignment control element 40 in the X direction is longer than the length of the display element 20 in the X direction. In FIG. 3, the right end of the alignment control element 40 is located to the right of the right end of the display element 20, and the left end of the alignment control element 40 is located to the left of the left end of the display element 20. The length of the alignment control element 40 in the Y direction is longer than the length of the display element 20 in the Y direction.

The optical element 50 reflects light incident from the bottom side to the top side. In addition, the optical element 50 reflects light incident obliquely from the bottom side, for example, in the front direction (normal direction). The detailed configuration of the optical element 50 will be described later.

The area of the optical element 50 is larger than that of the display element 20 and smaller than that of the alignment control element 40. The length in the X direction of the optical element 50 is longer than that of the display element 20 and shorter than that of the alignment control element 40. In FIG. 3, the right end of the optical element 50 is located between the right end of the display element 20 and the right end of the alignment control element 40, and the left end of the optical element 50 is located between the left end of the display element 20 and the left end of the alignment control element 40. The length in the Y direction of the optical element 50 is longer than that of the display element 20 and shorter than that of the alignment control element 40.

The optical element 50 forms an aerial image 2 in the air. The aerial image 2 is parallel to the element surface of the optical element 50 and is a two-dimensional image. The element surface refers to a virtual plane on which the optical element 50 extends in the in-plane direction. The element surface has the same meaning as in-plane. The element surfaces of the other elements have the same meaning. An observer 3 standing in front of the optical element 50 can view the aerial image 2.

The housing 60 has a rectangular frame shape and has four side panels. The side panels of the housing 60 have an inverted L-shaped cross section. A rectangular opening 61 is provided in the upper part of the housing 60, and a step is provided along the periphery of the opening 61. The optical element 50 is placed on the step in the upper part of the housing 60 and fitted into the opening 61. The housing 60 and the optical element 50 are bonded together with a transparent adhesive.

The area of the opening at the bottom of the housing 60 is set to be the same as the area of the alignment control element 40. The alignment control element 40 is fitted into the opening at the bottom of the housing 60. The housing 60 and the alignment control element 40 are bonded together with a transparent adhesive.

It is desirable that the housing 60 be made of a material capable of reducing light reflection. The housing 60 is made of, for example, black resin. For example, the inner surface of the housing 60 is roughened. The roughened surface can reduce light reflection.

The bottom of the housing 60 may have any configuration. The housing 60 may be configured in a box shape capable of housing the lighting element 10, the display element 20, the light absorbing layer 30, the orientation control element 40, and the optical element 50, that is, may be configured as a box having a bottom plate disposed below the lighting element 10.

[1-1-1] Configuration of the alignment control element 40 Fig. 5A is a plan view of the alignment control element 40 shown in Fig. 1. Fig. 5B is a cross-sectional view of the alignment control element 40 taken along the line BB' in Fig. 5A.

The substrate 41 is configured to be planar in the XY plane and has a rectangular parallelepiped shape. The substrate 41 transmits light.

On the substrate 41, a plurality of transparent members 43 are provided, each extending in the Y direction and aligned in the X direction. Also, on the substrate 41, a plurality of light-shielding members 44 are provided, each extending in the Y direction and aligned in the X direction. The plurality of transparent members 43 and the plurality of light-shielding members 44 are alternately arranged such that adjacent ones are in contact with each other.

A substrate 42 is provided on the plurality of transparent members 43 and the plurality of light-shielding members 44. The substrate 42 is configured to be planar in the XY plane and has a rectangular parallelepiped shape. The substrate 42 transmits light.

The transparent member 43 extends in an oblique direction at an angle θ ₁ in the XZ plane with respect to the normal direction of the base material 41. The transparent member 43 is a parallelogram with side surfaces inclined at an angle θ ₁ in the XZ plane. The transparent member 43 transmits light.

The light blocking member 44 extends in an oblique direction at an angle θ ₁ with respect to the normal direction of the base material 41 in the XZ plane. The light blocking member 44 is a parallelogram with side surfaces inclined by an angle θ ₁ in the XZ plane. The light blocking member 44 blocks light. The thickness of the light blocking member 44 is set to be thinner than the thickness of the transparent member 43.

Two adjacent light blocking members 44 are positioned so that their ends slightly overlap in the Z direction.

Glass or transparent resin (including acrylic resin) is used for the base materials 41 and 42 and the transparent member 43. For example, resin mixed with black dye or pigment is used for the light blocking member 44.

The alignment control element 40 may be constructed by omitting one or both of the substrates 41 and 42. The function of the alignment control element 40 can be realized if multiple transparent members 43 and multiple light-shielding members 44 are arranged alternately.

The orientation control element 40 configured in this manner can transmit the display light so that the light intensity in the oblique direction at an angle θ ₁ with respect to the normal direction becomes a peak. For example, the orientation control element 40 is configured to block light components other than the range of 30°±30° with respect to the normal direction. Desirably, the orientation control element 40 is configured to block light components other than the range of 30°±20° with respect to the normal direction.

Figure 6 is a schematic cross-sectional view illustrating the area of the alignment control element 40. In this embodiment, the alignment control element 40, which is an element facing the optical element 50, is set to have a length in at least the X direction that is longer than the length of the optical element 50 in the X direction.

Point "o'" in FIG. 6 is an arbitrary position of the light emitted from the orientation control element 40. Point "o''" in FIG. 6 is the position where the light emitted from the optical element 50 is focused, and is the position where the aerial image 2 is formed. The arrow extending from point "o'' represents the chief ray. The chief ray is a ray that passes through the center of the radially expanding light components.

The length I of the orientation control element 40 in the X direction is expressed by the following formula (1).
I≦x+2*x′=x+2*y′*tan _θ e (1)
x'=y'*tan θ _e
x: length of opening 61 of housing 60 in the X direction y: distance from optical element 50 to aerial image 2 x': distance from optical element 50 to an end of housing 60 in the X direction y': distance from optical element 50 to orientation control element 40 _θe : emission angle of chief ray (angle between the perpendicular to orientation control element 40 and the chief ray)

The length x of the opening 61 in the X direction is a design value that is designed based on the specifications required for the aerial display device 1. The distance y from the optical element 50 to the aerial image 2 is a design value that is designed based on the specifications required for the aerial display device 1. The distance y' from the optical element 50 to the orientation control element 40 is a design value that is optimally designed based on the distance y.

The longer the length I of the orientation control element 40 in the X direction, the larger the size of the housing 60. Therefore, from the perspective of reducing the size of the housing 60, "I = x + 2 * x'" is most desirable.

In addition, the length of the orientation control element 40 in the Y direction is set to be longer than the length of the optical element 50 in the Y direction.

[1-1-2] Configuration of the Optical Element 50 Fig. 7 is a perspective view of the optical element 50 shown in Fig. 1. Fig. 7 also shows an enlarged view of a portion of the optical element 50. The enlarged view in Fig. 7 is a side view in the XZ plane.

The optical element 50 includes a substrate 51 and a plurality of optical elements 52. The substrate 51 is configured to be planar in the XY plane and has a rectangular parallelepiped shape.

A plurality of optical elements 52 are provided on the bottom surface of the substrate 51. Each of the plurality of optical elements 52 is formed as a triangular prism. The optical element 52 is arranged so that three side surfaces of the triangular prism are parallel to the XY plane, and one side surface is in contact with the substrate 51. The plurality of optical elements 52 each extend in the Y direction and are arranged side by side in the X direction. In other words, the plurality of optical elements 52 have a sawtooth shape in the XZ plane.

Each of the multiple optical elements 52 has an incident surface 53 and a reflective surface 54. When viewed from the Y direction, the left side surface is the incident surface 53, and the right side surface is the reflective surface 54. The incident surface 53 is a surface onto which light from the display element 20 is incident. The reflective surface 54 is a surface that reflects light that has been incident on the incident surface 53 from the outside, within the optical element 52. The incident surface 53 and the reflective surface 54 form an angle θ _p .

The substrate 51 and the optical element 52 are made of a transparent material. The optical element 52 is, for example, formed integrally with the substrate 51 using the same transparent material as the substrate 51. The substrate 51 and the optical element 52 may be formed separately, and the optical element 52 may be adhered to the substrate 51 using a transparent adhesive. The transparent material constituting the substrate 51 and the optical element 52 may be glass or a transparent resin (including an acrylic resin).

The optical element 50 configured in this way internally reflects incident light and forms a real image in the air. The optical element 50 also forms an aerial image at a position directly in front of the element surface.

[1-1-3] Block configuration of the aerial display device 1 Figure 8 is a block diagram of the aerial display device 1. The aerial display device 1 includes 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.

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.

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

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 realizes 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.

The display processing unit 70A controls the operation of the display unit 73 (specifically, the lighting element 10 and the display element 20). The display processing unit 70A controls the on and off of the lighting element 10. The display processing unit 70A transmits an image signal to the display element 20, causing the display element 20 to display an image.

The information processing unit 70B generates an image to be displayed by the aerial display device 1. The information processing unit 70B can use image data stored in the memory unit 71. The information processing unit 70B may also acquire image data from outside using a communication function (not shown).

The storage unit 71 includes non-volatile storage devices such as a ROM (Read Only Memory), a HDD (Hard Disk Drive), and a SSD (Solid State Drive), and volatile storage devices such as a RAM (Random Access Memory) and a register. The storage unit 71 stores programs executed by the control unit 70. The storage unit 71 stores various data necessary for the control of the control unit 70. Furthermore, the storage unit 71 stores data for images displayed by the aerial display device 1.

The input unit 74 includes, for example, a touch panel or buttons, and receives information input by the user. The information processing unit 70B can select an image to be displayed on the display unit 73 based on the information received by the input unit 74.

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

[1-2-1] Display operation The arrows in Fig. 4 indicate light paths. As shown in Fig. 4, light emitted from an arbitrary point "o" of the display element 20 is incident on the orientation control element 40. Of the light emitted from the display element 20, a light component at an angle _θ1 (including a light component in a predetermined angle range centered on the angle _θ1 ) is transmitted through the orientation control element 40. The light transmitted through the orientation control element 40 is incident on the optical element 50. The optical element 50 forms an image of the incident light in the air on the opposite side to the orientation control element 40, and displays an aerial image 2 in the air.

Figure 9 is a perspective view illustrating how light is reflected in the optical element 50. Figure 10 is a side view of the XZ plane illustrating how light is reflected in the optical element 50. Figure 10 is a view of the optical element 50 when both eyes of the observer 3 (i.e., the line connecting both eyes) are parallel to the X direction. Figure 11 is a side view of the YZ plane illustrating how light is reflected in the optical element 50. Figure 11 is a view of the optical element 50 when both eyes of the observer 3 are parallel to the Y direction.

Light emitted from any point "o'" of the orientation control element 40 enters the incident surface 53 of the optical element 50 and reaches the reflecting surface 54. Light that reaches the reflecting surface 54 at an angle greater than the critical angle with respect to the normal direction of the reflecting surface 54 is totally reflected by the reflecting surface 54 and is emitted from the flat surface opposite the side on which the optical element 50's optical elements 52 are formed. The critical angle is the smallest incident angle above which total reflection occurs. The critical angle is the angle with respect to the normal to the incident surface.

In the XZ plane of FIG. 10, the light emitted from point "o'" is totally reflected by the reflecting surface 54 of the optical element 52, and the light is focused in the air to generate an aerial image.

In the YZ plane of FIG. 11, the light emitted from point "o'" is not reflected by the reflecting surface 54 of the optical element 52, and the light does not form an image in the air, so it does not contribute to the generation of an aerial image.

In other words, the condition for observer 3 to be able to recognize the aerial image is that both eyes of observer 3 are parallel to the X direction or close to it (for example, ±10 degrees with respect to the X direction). Also, if observer 3's eyes are parallel to the X direction or close to it and the viewpoint is moved along the Y direction, the aerial image can always be recognized.

Figure 12 is a diagram explaining the angular conditions of the incident surface 53 and the reflecting surface 54 of the optical element 50.

The angle of the incident surface 53 with respect to the Z direction (the direction perpendicular to the element surface) is θ ₂ , the angle of the reflecting surface 54 with respect to the Z direction is θ ₃ , and the angle between the incident surface 53 and the reflecting surface 54 is θ _p . The angle θ _p is expressed by the following equation (2).
θ _p = θ ₂ + θ ₃ ... (2)

Light emitted from orientation control element 40 at angle θ ₁ is incident on incident surface 53. The refractive index of the material of optical element 50 is n _p , and the refractive index of air is 1. The incident angle at incident surface 53 is θ ₄ , and the refraction angle is θ _5. The incident angle at reflecting surface 54 is θ ₆ , and the reflection angle is θ ₇ (=θ ₆ ). The incident angle at the top surface of optical element 50 is θ ₈ , and the refraction angle is θ _9. The refraction angle θ ₉ is the emission angle. The emission angle θ ₉ is expressed by the following equation (3).
θ ₉ =sin ⁻¹ (n _p *sin(sin ⁻¹ ((1/n _p ) *sin(90°-(θ ₁ +θ ₂ )))) + θ ₂ + 2θ ₃ -90°)) ... (3)

The critical angle at the reflecting surface 54 is expressed by the following formula (4).
Critical angle < θ ₆ (= θ ₇ )
Critical angle = sin ⁻¹ (1/n _p ) (4)

That is, the angle of incidence _θ6 on the reflecting surface 54 is set to be larger than the critical angle on the reflecting surface 54. In other words, the angle _θ3 of the reflecting surface 54 is set so that the angle of incidence of light incident on the reflecting surface 54 is larger than the critical angle.

Moreover, the angle θ2 of the incident surface 53 is set so that the light incident on the incident surface 53 is not totally reflected by the incident surface 53. In other words, the angle _θ2 of the incident surface 53 is set so that the angle of incidence of the light incident on the incident surface 53 is smaller than the critical angle.

The angle between the element surface of the optical element 50 and the surface of the aerial image 2, and the distance between the element surface of the optical element 50 and the surface of the aerial image 2 can be adjusted by optimally setting the angle θ ₁ of light incident on the optical element 50, the refractive index of the optical element 50, the angle θ ₂ of the incident surface 53 of the optical element 50, and the angle θ ₃ of the reflecting surface 54 of the optical element 50.

[1-2-2] Effects of external light Next, the effects of external light incident on the aerial display device 1 will be described. External light is incident on the aerial display device 1. External light is light that is incident on the aerial display device 1 from outside the aerial display device 1. External light includes sunlight and light from indoor lighting fixtures. External light is unpolarized natural light.

Figure 13 is a diagram explaining the state of external light entering the aerial display device 1.

External light that is incident on the area of the aerial display device 1 occupied by the display element 20 in a plan view (including the area of the orientation control element 40 at point "A" in Figure 13) passes through the optical element 50 and enters the orientation control element 40. The external light that is incident on the orientation control element 40 is absorbed by the light blocking member 44 included in the orientation control element 40. Therefore, the external light that is incident on the area of the aerial display device 1 occupied by the display element 20 is reflected inside the aerial display device 1, and can be prevented from being emitted from the top surface of the aerial display device 1.

External light that is incident on an area of the aerial display device 1 other than the area occupied by the display element 20 in a plan view (including the area of point "B" in FIG. 13 of the orientation control element 40) passes through the optical element 50 and enters the orientation control element 40. The external light that is incident on the orientation control element 40 is absorbed by the light blocking member 44 included in the orientation control element 40. Therefore, external light that is incident on an area of the aerial display device 1 other than the area occupied by the display element 20 is reflected inside the aerial display device 1, and can be prevented from being emitted from the top surface of the aerial display device 1.

As a result, deterioration in the quality of the aerial image 2 displayed by the aerial display device 1 due to external light entering the aerial display device 1 can be suppressed.

Furthermore, light incident on the aerial display device 1 from below is absorbed by the light absorbing layer 30. This makes it possible to prevent deterioration in the quality of the aerial image 2 displayed by the aerial display device 1 due to light incident on the aerial display device 1 from below.

14 is a cross-sectional view of a modified aerial display device 1. The display element 20 and the alignment control element 40 may be bonded with a transparent adhesive 21.

[1-4] Comparative Example Next, an aerial display device 1A according to a comparative example will be described.
Fig. 15 is an exploded view of the aerial display device 1A according to the comparative example. Fig. 16 is a partial cross-sectional view of the aerial display device 1A according to the comparative example taken along the X direction.

The aerial display device 1A includes an illumination element 10, a display element 20, an orientation control element 40, an optical element 50, and a housing 60. The illumination element 10, the display element 20, the orientation control element 40, and the optical element 50 are arranged in this order along the Z direction and parallel to each other.

The aerial display device 1A of the comparative example does not have the light absorbing layer 30 shown in the first embodiment. The area of the alignment control element 40 is approximately the same as the area of the display element 20. The area of the optical element 50 is larger than the area of the alignment control element 40. The length of the optical element 50 in the X direction is longer than the length of the alignment control element 40 in the X direction.

The housing 60 has a rectangular shape and has four side panels and a bottom panel. The housing 60 is made of, for example, black resin. A rectangular opening 62 is provided in the bottom panel of the housing 60. The opening 62 passes light emitted from the display element 20. The area of the opening 62 is approximately the same as the area of the alignment control element 40.

Figure 17 is a diagram explaining the state of external light entering the aerial display device 1A.

External light that is incident on the area of the aerial display device 1A occupied by the display element 20 in a plan view (including the area of the orientation control element 40 at point "A" in Figure 17) passes through the optical element 50 and enters the orientation control element 40. The external light that is incident on the orientation control element 40 is absorbed by the light blocking member 44 included in the orientation control element 40. Therefore, the external light that is incident on the area of the aerial display device 1A occupied by the display element 20 is reflected inside the aerial display device 1A, and is prevented from being emitted from the top surface of the aerial display device 1A.

Of the external light incident on the aerial display device 1A, the light components that reach the bottom plate of the housing 60 are diffusely reflected by the bottom plate of the housing 60. The light components diffusely reflected by the housing 60 are reflected by the optical element 50 toward the observer and are visible to the observer.

Figure 18 is a diagram explaining the display element image and the aerial image. The display element image is an image displayed on the display surface of the display element 20. The aerial image is a real image formed by the optical element 50.

In addition to the display element image, the aerial image contains a double frame formed due to external light. The frame shifted to the right in Figure 18 is seen based on the external light diffusely reflected to the right at point "B" in Figure 17. The frame shifted to the left in Figure 18 is seen based on the external light diffusely reflected to the left at point "B" in Figure 17. In this way, when external light is diffusely reflected inside the aerial display device 1A, the quality of the aerial image generated by the aerial display device 1A deteriorates.

In contrast, in the first embodiment, the component surface (the upper surface of the orientation control element 40) that is arranged opposite the optical element 50 is expanded. This makes it possible to suppress reflection of external light inside the aerial display device.

[1-5] Effects of the First Embodiment In the first embodiment, the aerial display device 1 includes a display element 20 that displays an image, an orientation control element 40 that is arranged to receive light from the display element 20 and transmits oblique light components of the light from the display element 20, an optical element 50 that is arranged to receive light from the orientation control element 40 and reflects the light from the orientation control element 40 to the opposite side of the orientation control element 40 to form an aerial image in the air, and a housing 60 that is configured to surround the periphery of the optical element 50 and fixes the optical element 50. The area of the element (the orientation control element 40 in this embodiment) that is arranged opposite the optical element 50 is set to be larger than the area of the optical element 50. That is, an element having a uniform surface is arranged as an element that faces the optical element 50.

External light is incident on the aerial display device 1 depending on the usage environment. The external light is light that is unnecessary for forming the aerial image 2. According to the first embodiment, it is possible to prevent the external light that is incident on the aerial display device 1 from being reflected inside the aerial display device 1 and being emitted from the aerial display device 1. This makes it possible to prevent deterioration in the quality of the aerial image 2 generated by the aerial display device 1. As a result, it is possible to realize an aerial display device 1 that is capable of improving display quality.

In addition, a light absorbing layer 30 is provided on the bottom surface of the alignment control element 40, and the light absorbing layer 30 has an opening 31 through which light from the display element 20 passes. This allows the light absorbing layer 30 to absorb light components that are not necessary for displaying the aerial image 2. This makes it possible to prevent the quality of the aerial image 2 from deteriorating.

The aerial display device 1 can display an aerial image in the air by reflecting light emitted from the display element 20 by the optical element 50. The aerial display device 1 can also display an aerial image in the front direction.

When the observer 3 looks at the optical element 50 with both eyes parallel to or close to the X direction (i.e., the direction in which the multiple optical elements 52 are arranged), the observer 3 can see an aerial image. When the observer 3 moves the viewpoint along the Y direction with both eyes parallel to or close to the X direction, the observer 3 can always see an aerial image. When the observer 3's eyes are parallel to or close to the X direction, a wider viewing angle can be achieved.

In addition, the multiple elements that make up the aerial display device 1 can be arranged in parallel. This makes it possible to realize an aerial display device 1 that can be made smaller in size in the Z direction.

In the first embodiment, the orientation control element 40 is disposed opposite the optical element 50. The area of the orientation control element 40 is set to be larger than the area of the optical element 50. In another configuration of the aerial display device 1, when the element opposite the optical element 50 is an element other than the orientation control element 40, the area of the element disposed opposite the optical element is set to be larger than the area of the optical element. This makes it possible to obtain the effect of this embodiment.

[2] Second Embodiment In the second embodiment, an anti-reflection layer 80 is provided on the upper surface of the element facing the optical element 50 .

Figure 19 is a cross-sectional view along the X direction of an aerial display device 1 according to a second embodiment of the present invention. Figure 19 corresponds to the cross-sectional view at the position of line A-A' in Figure 2. The aerial display device 1 according to the second embodiment includes an anti-reflection layer 80 in addition to the configuration of the first embodiment.

The anti-reflection layer 80 is provided on the alignment control element 40. The area of the anti-reflection layer 80 is the same as the area of the alignment control element 40. The anti-reflection layer 80 has the function of suppressing the reflection of light incident on the anti-reflection layer 80. The anti-reflection layer 80 is made of a transparent material, and is, for example, made by stacking multiple layers with different refractive indices. The anti-reflection layer 80 is also called a reflection suppression layer.

Figure 20 is a diagram explaining the state of light reflected inside the aerial display device 1. The configuration example in Figure 20 does not include an anti-reflection layer 80, and the upper surface of the alignment control element 40 faces the optical element 50.

External light incident on the aerial display device 1 passes through the optical element 50. A portion of the light that passes through the optical element 50 is reflected by the upper surface of the orientation control element 40. A portion of the light that is repeatedly reflected between the optical element 50 and the orientation control element 40 (return light in FIG. 20) passes through the optical element 50 and is emitted toward the observer. Therefore, the quality of the aerial image 2 may deteriorate due to internal reflection of the external light.

In contrast, in this embodiment, an anti-reflection layer 80 is provided on the surface facing the optical element 50. This makes it possible to suppress internal reflection of external light that has passed through the optical element 50. This improves the quality of the aerial image 2.

[3] Third embodiment In the third embodiment, a transparent support member 32 is disposed so as to face the entire surface of the optical element 50. Furthermore, a light absorbing layer 30 is disposed on the bottom surface of the support member 32. The support member 32 and the light absorbing layer 30 are utilized to prevent external light from being diffusely reflected inside the aerial display device 1 and emitted toward the observer.

[3-1] Configuration of the aerial display device 1 Fig. 21 is an exploded view of the aerial display device 1 according to the third embodiment of the present invention. Fig. 22 is a cross-sectional view along the X direction of the aerial display device 1 shown in Fig. 21. Fig. 22 corresponds to the cross-sectional view at the position of the line A-A' in Fig. 2.

The aerial display device 1 comprises an illumination element 10, a display element 20, an orientation control element 40, a light absorbing layer 30, a support member 32, an optical element 50, and a housing 60. The illumination element 10, the display element 20, the orientation control element 40, the light absorbing layer 30, the support member 32, and the optical element 50 are arranged in this order along the Z direction and parallel to one another. The illumination element 10, the display element 20, and the orientation control element 40 are fixed at desired positions with a fixing member (not shown) so as to leave a desired distance between each other.

The area of the alignment control element 40 is approximately the same as the area of the display element 20. The length of the alignment control element 40 in the X direction is approximately the same as the length of the display element 20 in the X direction. The length of the alignment control element 40 in the Y direction is approximately the same as the length of the display element 20 in the Y direction.

The light absorbing layer 30 has a rectangular opening 31. The opening 31 has the same area as the alignment control element 40 and exposes the alignment control element 40. The light absorbing layer 30 is provided on the bottom surface of the support member 32 and is attached to the bottom surface of the support member 32. The outer periphery of the light absorbing layer 30 extends to the outer periphery of the support member 32.

The support member 32 is provided above the alignment control element 40 and is adhered to the alignment control element 40 using, for example, a transparent adhesive. The support member 32 is made of a transparent material and transmits light. The support member 32 is made of glass or a transparent resin (including acrylic resin).

The area of the support member 32 is larger than the area of the alignment control element 40. The length of the support member 32 in the X direction is longer than the length of the alignment control element 40 in the X direction. In FIG. 22, the right end of the support member 32 is located to the right of the right end of the alignment control element 40, and the left end of the support member 32 is located to the left of the left end of the alignment control element 40. The length of the support member 32 in the Y direction is longer than the length of the alignment control element 40 in the Y direction.

The optical element 50 is disposed opposite the support member 32. The area of the optical element 50 is larger than that of the orientation control element 40 and smaller than that of the support member 32. The length in the X direction of the optical element 50 is longer than that of the orientation control element 40 and shorter than that of the support member 32. In FIG. 22, the right end of the optical element 50 is located between the right end of the orientation control element 40 and the right end of the support member 32, and the left end of the optical element 50 is located between the left end of the orientation control element 40 and the left end of the support member 32. The length in the Y direction of the optical element 50 is longer than that of the orientation control element 40 and shorter than that of the support member 32.

The area of the opening at the bottom of the housing 60 is set to be the same as the area of the support member 32. The support member 32 is fitted into the opening at the bottom of the housing 60. The housing 60 and the support member 32 are bonded together with a transparent adhesive.

[3-2] Influence of External Light Next, we will explain the influence of external light incident on the aerial display device 1. Figure 23 is a diagram explaining the state of external light incident on the aerial display device 1.

External light that is incident on the area of the aerial display device 1 occupied by the display element 20 in a plan view (including the area of the orientation control element 40 at point "A" in Figure 23) passes through the optical element 50 and enters the orientation control element 40. The external light that is incident on the orientation control element 40 is absorbed by the light blocking member 44 included in the orientation control element 40. Therefore, the external light that is incident on the area of the aerial display device 1 occupied by the display element 20 is reflected inside the aerial display device 1, and can be prevented from being emitted from the top surface of the aerial display device 1.

External light that is incident on the aerial display device 1 in a plan view other than the area occupied by the display element 20 (including the area of point "B" in Figure 23 of the support member 32) passes through the optical element 50 and enters the support member 32. The light that is incident on the support member 32 is absorbed by the light absorbing layer 30. Therefore, external light that is incident on the aerial display device 1 in an area other than the area occupied by the display element 20 is reflected inside the aerial display device 1, and is prevented from being emitted from the top surface of the aerial display device 1.

As a result, deterioration in the quality of the aerial image 2 displayed by the aerial display device 1 due to external light entering the aerial display device 1 can be suppressed.

Furthermore, light incident on the aerial display device 1 from below is absorbed by the light absorbing layer 30. This makes it possible to prevent deterioration in the quality of the aerial image 2 displayed by the aerial display device 1 due to light incident on the aerial display device 1 from below.

[3-3] Modifications Fig. 24 is a cross-sectional view of a modified aerial display device 1. The display element 20 and the alignment control element 40 may be bonded with a transparent adhesive 21. The alignment control element 40 and the support member 32 may be bonded with a transparent adhesive 22.

[3-4] Advantages of the Third Embodiment According to the third embodiment, it is possible to suppress deterioration of the quality of the aerial image 2 displayed by the aerial display device 1. The other advantages are the same as those of the first embodiment.

It is also possible to apply the second embodiment to the third embodiment. That is, an anti-reflection layer 80 may be further provided on the upper surface of the support member 32.

In addition, in the third embodiment, the orientation control element 40 may be omitted to configure the aerial display device 1.

[4] Other Examples In the above embodiment, the display element 20 and the optical element 50 are arranged parallel to each other. However, this is not limiting, and the display element 20 may be arranged obliquely with respect to the optical element 50. The angle between the display element 20 and the optical element 50 is set in the range of more than 0 degrees and less than 45 degrees.

In the above embodiment, the left side of the optical element 52 is defined as the incident surface 53, and the right side is defined as the reflective surface 54. However, this is not limited to this, and the incident surface 53 and the reflective surface 54 may be configured in reverse. In this case, the action of the aerial display device 1 described in the embodiment is also reversed.

In the above embodiment, a liquid crystal display element is described as an example of the display element 20, but the present invention is not limited to this. The display element 20 may be a self-luminous organic EL (electroluminescence) display element or a micro LED (Light Emitting Diode) display element. A micro LED display element is a display element that uses LEDs to emit the R (red), G (green), and B (blue) that make up a pixel. When a self-luminous display element 20 is used, the illumination element 10 is not necessary.

The present invention is not limited to the above-described embodiments, and can be modified in various ways in the implementation stage without departing from the gist of the invention. The embodiments may also be implemented in appropriate combination, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combinations selected from the multiple constituent elements disclosed. For example, if the problem can be solved and an effect can be obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the configuration from which these constituent elements are deleted can be extracted as an invention.

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, 21, 22...adhesive, 30...light absorbing layer, 31...opening, 32...support member, 40...orientation control element, 41, 42...substrate, 43...transparent member, 44...light-shielding member, 50...optical element, 51...substrate, 52...optical element, 53...incident surface, 54...reflective surface, 60...housing, 61, 62...opening, 70...control unit, 70A...display processing unit, 70B...information processing unit, 71...memory unit, 72...input/output interface, 73...display unit, 74...input unit, 75...bus, 80...anti-reflection layer.

Claims (14)

A display element for displaying an image;
an optical element that is arranged to receive light from the display element, and that reflects the light from the display element to an opposite side to the display element to form an aerial image in the air;
a housing configured to surround the periphery of the optical element and to fix the optical element;
Equipped with
An aerial display device, wherein an area of an element arranged opposite the optical element is larger than an area of the optical element. an orientation control element disposed between the display element and the optical element, the orientation control element transmitting an oblique light component of the light from the display element;
The aerial display device according to claim 1 , wherein the area of the orientation control element is larger than the area of the optical element. The aerial display device according to claim 2 , wherein an outer periphery of the orientation control element extends to the housing. The aerial display device according to claim 2 , further comprising a light absorbing layer provided on a bottom surface of the alignment control element, the light absorbing layer having an opening through which light from the display element passes, and absorbing light. The aerial display device according to claim 4 , wherein an outer periphery of the light absorbing layer extends to an outer periphery of the alignment control element. the alignment control element includes a plurality of transparent members and a plurality of light blocking members arranged alternately;
The aerial display device according to claim 2 , wherein the plurality of light blocking members are inclined with respect to a normal direction of the alignment control element. The aerial display device according to claim 2 , further comprising an anti-reflection layer provided on an upper surface of the alignment control element. a transparent support member disposed between the display element and the optical element;
The aerial display device according to claim 1 , wherein the area of the support member is larger than the area of the optical element. The aerial display device according to claim 8 , wherein an outer periphery of the support member extends to the housing. The aerial display device according to claim 8 , further comprising a light absorbing layer provided on a bottom surface of the support member, the light absorbing layer having an opening through which light from the display element passes, and absorbing light. The aerial display device according to claim 10 , wherein the outer periphery of the light absorbing layer extends to the outer periphery of the support member. The aerial display device according to claim 8 , further comprising an anti-reflection layer provided on an upper surface of the support member. The optical element includes a planar substrate and a plurality of optical elements provided under the substrate, each of the optical elements extending in a first direction and aligned in a second direction perpendicular to the first direction;
The aerial display device according to claim 1 , wherein each of the optical elements has an incident surface and a reflecting surface that are inclined with respect to a normal direction of the base material and are in contact with each other. The aerial display device according to claim 1 , wherein the display element and the optical element are arranged parallel to each other.