Floating image display device

Abstract

A floating image display device according to the present disclosure includes a display device and a reflective element that reflects image light from the display device and displays the reflected image light as a floating image. The reflective element includes a transparent substrate having a first surface and a second surface, and reflective surfaces disposed inside the transparent substrate and arranged parallel to each other at intervals such that the surface direction intersects the first surface. The reflective surfaces include a plurality of first reflective surfaces located closer to the first surface, a plurality of third reflective surfaces and a plurality of second reflective surfaces each located on the second surface side from the plurality of first reflective surfaces, the plurality of second reflective surfaces having a different arrangement direction than the plurality of first reflective surfaces and the plurality of third reflective surfaces having a different arrangement direction than the plurality of second reflective surfaces, and a plurality of fourth reflective surfaces located closer to the second surface than the plurality of second reflective surfaces and the plurality of third reflective surfaces, the plurality of fourth reflective surfaces having a different arrangement direction than the plurality of third reflective surfaces. The image light is reflected successively by the first, second, third, and fourth reflective surfaces.

Description

Floating Image Display

[0001] The present disclosure relates to a floating image display device.

[0002] 2. Description of the Related Art A floating image display device is known from the past, for example, as described in Patent Document 1.

[0003] JP 2012-014194 A

[0004] The floating image display device of the present disclosure is a floating image display device comprising: a display device; and a reflective element that displays image light emitted from the display device as a floating image of a real image by reflecting the image light in a direction different from the direction toward the display device, wherein the reflective element includes a transparent substrate having a first surface and a second surface facing each other, and reflective surfaces located inside the transparent substrate and arranged parallel to each other at intervals whose surface directions intersect with the first surface, wherein the reflective surfaces include: a plurality of first reflective surfaces located closer to the first surface; a plurality of second reflective surfaces and a plurality of third reflective surfaces that are each located closer to the second surface than the plurality of first reflective surfaces and have an arrangement direction different from that of the plurality of second reflective surfaces; and a plurality of fourth reflective surfaces located closer to the second surface than the plurality of second reflective surfaces and the plurality of third reflective surfaces and have an arrangement direction different from that of the plurality of third reflective surfaces, wherein the image light travels along an optical path in which it is sequentially reflected by the first reflective surface, the second reflective surface, the third reflective surface, and the fourth reflective surface.

[0005] Objects, features, and advantages of the present disclosure will become clearer from the following detailed description and drawings.

[0023] FIG. 1 is a perspective view showing a floating image display device according to an embodiment of the present disclosure.

[0024] FIG. 2 is a side view showing a floating image display device according to an embodiment of the present disclosure.

[0025] FIG. 3 is an exploded perspective view showing a reflective element of the floating image display device of FIG. 2.

[0026] FIG. 4 is a plan view showing a reflective element of the floating image display device of FIG. 2.

[0027] FIG. 5 is a plan view explaining an example of a cause of degradation in resolution of a floating image.

[0028] FIG. 6 is a plan view explaining a ray spacing in a conventional floating image display device.

[0029] FIG. 7 is a plan view explaining a ray spacing in a floating image display device according to an embodiment of the present disclosure.

[0030] FIG. 8 is a graph showing the relationship between the crossing angle and the average ray spacing in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device.

[0031] FIG. 9 is a graph showing the relationship between the crossing angle and the average ray spacing in consideration of the diffraction width in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device.

[0032] FIG. 10 is a graph showing the relationship between the crossing angle and the rate of change of the average ray spacing in consideration of the diffraction width and the rate of change in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device. Fig. 13 is a side view showing a floating image display device according to another embodiment of the present disclosure. Fig. 14 is an exploded perspective view showing a reflective element of the floating image display device of Fig. 12. Fig. 15 is a plan view showing another example of the reflective element of the floating image display device of Figs. 2 and 12.

[0006] Patent Document 1 describes a floating image display device that displays image light emitted from a display device as a floating image using a flat optical imaging device.

[0007] The optical imaging device of a conventional floating image display device may focus the light emitted from each pixel of the display device with a relatively large spatial spread, which may result in a reduction in the resolution of the floating image.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the drawings referred to below shows the main components of a floating image display device according to an embodiment. The floating image display device according to an embodiment may also include well-known components such as a circuit board, wiring conductors, a control IC, and a housing, which are not shown. Each of the drawings referred to below is a schematic diagram, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0009] Fig. 1 is a perspective view showing a floating image display device of the present disclosure, Fig. 2 is a side view showing a floating image display device of an embodiment of the present disclosure, Fig. 3 is an exploded perspective view showing a reflective element of the floating image display device of Fig. 2, and Fig. 4 is a plan view showing a reflective element of the floating image display device of Fig. 2. Fig. 5 is a plan view explaining an example of a cause of resolution degradation of a floating image, Fig. 6 is a plan view explaining the ray spacing in a conventional floating image display device, and Fig. 7 is a plan view explaining the ray spacing in a floating image display device according to an embodiment of the present disclosure. Fig. 8 is a graph showing the relationship between the crossing angle and the average ray spacing in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device, Fig. 9 is a graph showing the relationship between the crossing angle and the average ray spacing taking into account the diffraction width in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device, Fig. 10 is a graph showing the relationship between the crossing angle and the rate of change of the average ray spacing in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device, and Fig. 11 is a graph showing the relationship between the crossing angle and the average ray spacing taking into account the diffraction width and the rate of change in a floating image display device according to an embodiment of the present disclosure and a conventional floating image display device. Also, Fig. 15 is a plan view showing another example of a reflective element of the floating image display device of Fig. 2.

[0010] 1, the floating image display device 1 of this embodiment includes a display device 2 and a reflective element 3. The floating image display device 1 displays a real floating image F by having the reflective element 3 reflect the image light L emitted from the display device 2 in a direction different from the direction toward the display device 2. That is, the display device 2 is located on the first surface 4a side of the transparent substrate 4, and the floating image F is located on the second surface 4b side of the transparent substrate 4. This configuration can prevent the display device 2 from being visible to the user 7.

[0011] The display device 2 and the floating image F may be positioned so as to overlap in a plan view. In this case, since the display device 2 and the floating image F are positioned symmetrically with respect to the transparent substrate 4, the position of the floating image F can be adjusted by adjusting the positional relationship between the display device 2 and the transparent substrate 4. For example, the floating image F can be placed in a position that is easy for the user 7 to see.

[0012] The display device 2 has a display surface 2a (shown in FIG. 2), and displays an original image on the display surface 2a, which is displayed as a floating image F. In other words, the display device 2 emits image light L of the image displayed as the floating image F from the display surface 2a. The display surface 2a has a plurality of pixels arranged in a matrix, and emits light that constitutes the image light L from each pixel.

[0013] The display device 2 may be a transmissive display device. The transmissive display device may be a liquid crystal display device including a backlight and a liquid crystal panel. The backlight may be a direct backlight having multiple light sources arranged two-dimensionally on the rear side of the liquid crystal panel. The backlight may be an edge-lit backlight having multiple light sources arranged on the periphery of the liquid crystal panel. The edge-lit backlight may have a lens array, a light guide plate, a diffusion plate, etc. for uniformly illuminating the liquid crystal panel. The light source may be, for example, a light-emitting diode (LED) element, a cold cathode fluorescent lamp, a halogen lamp, a xenon lamp, etc. The LED element may be a mini LED element or a micro LED element.

[0014] The liquid crystal panel may be a known liquid crystal panel, such as an IPS (In-Plane Switching) type, an FFS (Fringe Field Switching) type, a VA (Vertical Alignment) type, or an ECB (Electrically Controlled Birefringence) type liquid crystal panel.

[0015] The transmissive display device is not limited to a liquid crystal display device, but may be a MEMS (Micro Electro Mechanical Systems) shutter type display device.

[0016] The display device 2 is not limited to a transmissive display device, and may be a self-luminous display device including light-emitting elements such as LED elements, organic light-emitting diode (OLED) elements, and semiconductor laser (LD) elements. The LED elements may be micro LED elements.

[0017] The floating image display device 1 includes a control unit (not shown). The control unit is connected to each component of the floating image display device 1 and controls each component. The control unit may constitute a part of the display device 2. The control unit is configured as, for example, a processor. The control unit may include one or more processors. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (ASIC). The processor may include a programmable logic device (PLD). The PLD may include an FPGA (field-programmable gate array). The control unit may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together. The control unit may include a memory unit that stores various information or programs for operating each component of the floating image display device 1. The memory unit may be configured, for example, with a semiconductor memory. The storage unit may function as a work memory for the control unit.

[0018] The reflective element 3 includes a transparent substrate 4 and a reflective surface 5 (shown in FIG. 3). The transparent substrate 4 has a first surface 4a (shown in FIG. 2) and a second surface 4b (shown in FIG. 2) located opposite the first surface 4a. The first surface 4a is also referred to as the incident surface, and the second surface 4b is also referred to as the exit surface. The reflective surface 5 is located inside the transparent substrate 4. The reflective element 3 is configured so that image light L emitted from the display device 2 enters the first surface 4a of the transparent substrate 4, is reflected by the reflective surface 5, exits from the second surface 4b of the transparent substrate 4, and is displayed as a floating image F. The first surface 4a of the transparent substrate 4 and the display surface 2a of the display device 2 may form an angle of, for example, approximately 10° to 45°. In this case, it is possible to reflect the image light L by the reflective surface 5 while suppressing an increase in the thickness of the transparent substrate 4. Note that "to" means "through," and the same applies hereinafter.

[0019] The transparent substrate 4 may be made of, for example, a transparent resin, a transparent glass, etc. The transparent resin may be, for example, an acrylic resin, an epoxy resin, a silicone resin, a polycarbonate resin, etc. The transparent glass may be, for example, a low-melting-point glass, a sol-gel glass, a borosilicate glass, a crystallized glass, quartz, a soda glass, etc.

[0020] The reflective surface 5 is configured to specularly reflect incident light. The reflective surface 5 may be the surface (one or the other principal surface) of a thin metal film 6 located inside the transparent substrate 4. The thin metal film 6 (shown in FIG. 3 ) may be made of a metal such as silver (Ag), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), platinum (Pt), or titanium (Ti), or an alloy thereof. The thin metal film 6 can be formed using a thin film formation method such as plating, vapor deposition, or CVD (Chemical Vapor Deposition). Both principal surfaces of the thin metal film 6 may have the same or approximately the same specular reflectance.

[0021] The surface direction of the reflective surface 5 (i.e., the direction in which the reflective surface 5 extends) intersects with the first surface 4a. The surface direction of the reflective surface 5 may be perpendicular or approximately perpendicular to the first surface 4a. In this case, the image light L reflected by the multiple reflective surfaces 5 can be efficiently emitted from the second surface 4b, thereby improving the light utilization efficiency of the floating image display device 1.

[0022] The reflecting surface 5 includes a plurality of first reflecting surfaces 51 , a plurality of second reflecting surfaces 52 , a plurality of third reflecting surfaces 53 , and a plurality of fourth reflecting surfaces 54 .

[0023] The multiple first reflecting surfaces 51 are located inside the transparent substrate 4 and closer to the incident surface 4a. The multiple first reflecting surfaces 51 are arranged parallel to one another at intervals. The surface direction of the first reflecting surfaces 51 intersects with the first surface 4a. The surface direction of the first reflecting surfaces 51 may be perpendicular or approximately perpendicular to the first surface 4a. In this specification, a structure in which the multiple reflecting surfaces 5 are located parallel to one another at intervals inside the transparent substrate 4 and whose surface direction intersects with the first surface 4a is referred to as a parallel arrangement structure. The multiple first reflecting surfaces 51 have a parallel arrangement structure.

[0024] The multiple second reflecting surfaces 52 are located closer to the second surface 4b than the multiple first reflecting surfaces 51. The multiple second reflecting surfaces 52 are located parallel to one another at intervals, and their surface directions intersect with the first surface 4a. That is, the multiple second reflecting surfaces 52 have a parallel arrangement structure. The surface directions of the second reflecting surfaces 52 may be perpendicular or approximately perpendicular to the first surface 4a. The multiple second reflecting surfaces 52 have an arrangement direction different from that of the multiple first reflecting surfaces 51. As shown in FIG. 4 , the first reflecting surfaces 51 and the second reflecting surfaces 52 may intersect at an acute angle in a plan view. In this specification, a plan view refers to a view from a direction perpendicular to the incident surface 4a and the exit surface 4b of the transparent substrate 4. The first reflecting surfaces 51 and the second reflecting surfaces 52 may intersect at an angle of 45° to 55° in a plan view.

[0025] The multiple third reflecting surfaces 53 are located closer to the second surface 4b than the multiple second reflecting surfaces 52. The multiple third reflecting surfaces 53 are located parallel to one another at intervals, and their surface directions intersect with the first surface 4a. That is, the multiple third reflecting surfaces 53 have a parallel arrangement structure. The surface direction of the third reflecting surfaces 53 may be perpendicular or approximately perpendicular to the first surface 4a. The multiple third reflecting surfaces 53 have an arrangement direction different from that of the multiple second reflecting surfaces 52. As shown in FIG. 4 , the second reflecting surface 52 and the third reflecting surface 53 may intersect at a right angle or approximately a right angle in a plan view. The second reflecting surface 52 and the third reflecting surface 53 may intersect at an angle of 89° or more and 91° or less in a plan view.

[0026] The multiple fourth reflecting surfaces 54 are located closer to the second surface 4b than the multiple second reflecting surfaces 52 and the multiple third reflecting surfaces 53. The multiple fourth reflecting surfaces 54 are located parallel to one another at intervals, and their surface directions intersect with the first surface 4a. That is, the multiple fourth reflecting surfaces 54 have a parallel arrangement structure. The surface direction of the fourth reflecting surfaces 54 may be perpendicular or approximately perpendicular to the first surface 4a. The multiple fourth reflecting surfaces 54 have an arrangement direction different from that of the multiple third reflecting surfaces 53. As shown in FIG. 4 , the third reflecting surface 53 and the fourth reflecting surface 54 may intersect at an acute angle in a plan view. The third reflecting surface 53 and the fourth reflecting surface 54 may intersect at an angle of 45° or more and 55° or less in a plan view. The fourth reflecting surface 54 extends along the first reflecting surface 51 in a plan view. The fourth reflecting surface 54 may extend parallel or approximately parallel to the first reflecting surface 51 in a plan view.

[0027] The intersection angle between the first surface 4a and the surface directions of the first reflecting surface 51, the second reflecting surface 52, the third reflecting surface 53, and the fourth reflecting surface 54 may be 80° to 100° (90°±10°). In this case, the intersection angle is a predetermined angle centered at 90°, and the image light L can be efficiently reflected from the first surface 4a to the second surface 4b along the shortest optical path or an optical path close to the shortest optical path. The intersection angle may be 85° to 95° or 88° to 93°, but is not limited to these ranges.

[0028] When the fourth reflecting surface 54, which is the final reflecting surface, extends parallel or approximately parallel to the first reflecting surface 51, which is the first reflecting surface, in a planar view, the incident light ray Lin (shown in FIGS. 2 and 4) incident on the reflecting element 3 from the display device 2 and the exit light ray Lout (shown in FIGS. 2 and 4) reaching the floating image F from the reflecting element 3 are parallel or approximately parallel in a planar view. In this case, as shown in FIG. 2, the display device 2 and the floating image F are positioned symmetrically in the vertical direction, and as shown in FIG. 4, the display device 2 and the floating image F are positioned so as to overlap in a planar view. An optical system that realizes a configuration with such a positional relationship may be referred to as a symmetrical optical system or a symmetrical plane optical system. Furthermore, the reflecting element 3 that achieves such a positional relationship may be referred to as a symmetrical optical element or a symmetrical plane optical element.

[0029] 5, the incident light beam Lin and the outgoing light beam Lout are parallel or nearly parallel in a plan view. This case also results in a symmetrical optical system. In the floating-image display device C, the fifth reflecting surface 55c, which is the first reflecting surface, and the sixth reflecting surface 56c, which is the last reflecting surface, intersect at a right angle (orthogonal) in a plan view.

[0030] From the above, a symmetrical optical system generally has a configuration in which the incident light ray Lin and the exit light ray Lout are parallel in a planar view (also referred to as configuration S1), and a configuration in which the first reflecting surface and the last reflecting surface are parallel or perpendicular in a planar view (also referred to as configuration S2). To facilitate the provision of configurations S1 and S2, a reflecting surface with a two-layer stacked structure, such as the reflecting element 3 of the conventional floating image display device C, or a reflecting surface with a four-layer stacked structure, such as the floating image display device 1 of this embodiment, may be provided. That is, a reflecting surface with a 2n-layer stacked structure (n is a natural number) may be provided. For example, a reflecting surface with a three-layer stacked structure makes it difficult for the incident light ray Lin and the exit light ray Lout to be parallel in a planar view, making it difficult to configure a symmetrical optical system. In addition, it becomes difficult for multiple exit light rays Lout to be focused into a single spot, which tends to reduce resolution.

[0031] A parallel array structure PA1 (shown in Figure 3) consisting of a plurality of first reflecting surfaces 51, a parallel array structure PA2 (shown in Figure 3) consisting of a plurality of second reflecting surfaces 52, a parallel array structure PA3 (shown in Figure 3) consisting of a plurality of third reflecting surfaces 53, and a parallel array structure PA4 (shown in Figure 3) consisting of a plurality of fourth reflecting surfaces 54 form a laminated structure stacked in the thickness direction of the transparent substrate 4.

[0032] In the floating image display device 1, the reflective element 3 is configured so that the image light L emitted from the display device 2 travels along an optical path in which it is sequentially reflected by the first reflective surface 51, the second reflective surface 52, the third reflective surface 53, and the fourth reflective surface 54. In FIGS. 2 and 4, the incident positions of the image light L on the first reflective surface 51, the second reflective surface 52, the third reflective surface 53, and the fourth reflective surface 54 are indicated by I1, I2, I3, and I4, respectively. The floating image display device 1 can retroreflect the light emitted from each pixel of the display device 2 in a planar view and focus the light at a single or approximately single point in space. As a result, the resolution of the floating image F can be improved. That is, the ray spacing between the incident light ray Lin incident on the reflective element 3 from the display device 2 and the outgoing light ray Lout from the reflective element 3 to the floating image F in a planar view is reduced, so that even if the ray spacing varies depending on the position of each reflective portion of the reflective element 3, the amount of variation is reduced. As a result, the imaging performance of the floating image F is improved, and the resolution of the floating image is improved.

[0033] The floating image display device 1 may be configured such that the first reflecting surface 51 and the second reflecting surface 52 intersect at 45° in a planar view, the first reflecting surface 51 and the third reflecting surface 53 intersect at 45° in a planar view, and the first reflecting surface 51 and the fourth reflecting surface 54 overlap in a planar view. In this case, it is possible to reduce the possibility that the image light L is not reflected sequentially by the first reflecting surface 51, the second reflecting surface 52, the third reflecting surface 53, and the fourth reflecting surface 54. As a result, it is possible to prevent the image light L from becoming stray light (i.e., light that travels toward the eyes of the user 7 but is not displayed as a floating image F), and it is possible to prevent the stray light from being viewed by the user 7 as a ghost image.

[0034] The multiple first reflecting surfaces 51 are arranged at a predetermined first interval G1 in a plan view. The multiple second reflecting surfaces 52 are arranged at a predetermined second interval G2 in a plan view. The multiple third reflecting surfaces 53 are arranged at a predetermined third interval G3 in a plan view. The multiple fourth reflecting surfaces 54 are arranged at a predetermined fourth interval G4 in a plan view. The first interval G1 and the fourth interval G4 may be the same or approximately the same. The second interval G2 and the third interval G3 may be the same or approximately the same.

[0035] The transparent substrate 4 (shown in FIG. 2) may have a layered structure including a first layer 41, a second layer 42, a third layer 43, and a fourth layer 44 stacked in this order. The first layer 41 includes an incident surface 4a, and the fourth layer 44 includes an exit surface 4b. A plurality of first reflecting surfaces 51, a plurality of second reflecting surfaces 52, a plurality of third reflecting surfaces 53, and a plurality of fourth reflecting surfaces 54 are located within the first layer 41, the second layer 42, the third layer 43, and the fourth layer 44, respectively.

[0036] The first layer 41, the second layer 42, the third layer 43, and the fourth layer 44 may each have a thickness of, for example, about 0.5 to 10 mm, or about 1.5 to 5.0 mm. The thicknesses of the first layer 41, the second layer 42, the third layer 43, and the fourth layer 44 may be the same as or different from one another.

[0037] Next, the effects of the floating image display device 1 will be described based on the results of optical simulations. Below, the effects of the floating image display device 1 will be described in comparison with a floating image display device (hereinafter referred to as "floating image display device C") that does not have the characteristics of the floating image display device 1. Note that, for the sake of convenience of explanation, the components of the floating image display device C may be given the same reference numerals as those given to the corresponding components of the floating image display device 1.

[0038] The floating image display device C differs from the floating image display device 1 in the configuration of the reflective element 3. The reflective element 3 of the floating image display device C is composed of a transparent substrate 4 and a lattice-shaped reflective surface 5c (shown in FIG. 5) located inside the transparent substrate 4. The lattice-shaped reflective surface 5c has a square lattice shape with a lattice spacing d in a plan view. The lattice-shaped reflective surface 5c is composed of a plurality of fifth reflective surfaces 55c and a plurality of sixth reflective surfaces 56c, and the fifth reflective surfaces 55c and the sixth reflective surfaces 56c intersect at a right angle in a plan view. The fifth reflective surface 55c is located on the side of the incident surface of the transparent substrate 4, and the sixth reflective surface 56c is located on the side of the exit surface of the transparent substrate 4. The fifth reflective surface 55c and the sixth reflective surface 56c are stacked in the thickness direction of the transparent substrate 4. Similar to the reflecting surface 5 of the floating image display device 1, the lattice-shaped reflecting surface 5c is the surface (one or the other main surface) of the metal thin film 6 located inside the transparent substrate 4, and is configured to specularly reflect incident light.

[0039] As shown in FIG. 5 , light rays ra, rb, and rc emitted from a point light source (one pixel of the display device 2) P toward the reflecting element 3 are reflected by the lattice-shaped reflecting surface 5c and then condensed into space. If the light rays ra, rb, and rc are not condensed to a single point or approximately a single point but are condensed with a spatial spread (shown by hatching in FIG. 5 ), the resolution of the floating image F formed by the image light L emitted from the display device 2 will deteriorate. If the ray spacing s between each of the light rays ra, rb, and rc in a planar view before entering the reflecting element 3 and after exiting the reflecting element 3 can be reduced, the light rays ra, rb, and rc can be accurately retroreflected in a planar view. As a result, the light rays ra, rb, and rc can be condensed substantially to a single point or very close to a single point, thereby improving the resolution of the floating image F.

[0040] Next, the ray spacing S, S used as a resolution index of the floating image F in this specification Ｃ This article explains:

[0041] FIG. 6 shows the light beam interval S in the floating image display device C. Ｃ 1 is a diagram illustrating the beam interval S Ｃis defined by the average value based on the sum of the ray intervals s for each of the two rays r1 and r2 when the rays r1 and r2 are incident on the reflecting element 3 of the floating image display device C. The two rays r1 and r2 are assumed to be parallel to each other. The two rays r1 and r2 are assumed to be incident on the reflecting element 3 with a predetermined interval (also referred to as the interval between incident rays) between them in a plan view. The ray interval S Ｃ is expressed by the formula (1).

[0042]

[0043] In equation (1), the first term represents the ray spacing s for the ray r1 in FIG. 6, and the second term represents the ray spacing s for the ray r2 in FIG. 6. As mentioned above, d is the lattice spacing of the lattice-shaped reflecting surface 5c, which was set to 5 mm in the optical simulations shown in FIGS. 8 to 11. g is a parameter representing the incident positions of the rays r1 and r2, and represents the distance from the lattice point LP of the lattice-shaped reflecting surface 5c to the position where the rays r1 and r2 are incident on the lattice-shaped reflecting surface 5c. As will be described later, the ray spacing S Ｃ By averaging with respect to the parameter g, the ray spacing S Ｃ Furthermore, the dependence of the beam spacing S on the incident position can be substantially eliminated. Ｃ By averaging with respect to the parameter g, the ray spacing S Ｃ This can substantially eliminate the dependency of the incident light beams on the spacing between the incident light beams. α is the angle of incidence of the light beams r1 and r2 with respect to the grating-like reflecting surface 5c, and β is the intersection angle between the grating-like reflecting surface 5c and the light beams r1 and r2. In the example shown in FIG. 6, α is the angle of incidence of the light beam r1 with respect to the fifth reflecting surface 55, and β is the intersection angle between the fifth reflecting surface 55 and the light beam r2. Note that α is the angle of incidence in a plan view, and β is the intersection angle in a plan view. α and β satisfy β = 90° - α, and it can also be said that β is the angle of incidence of the light beam r2 with respect to the sixth reflecting surface 56.

[0044] 7 is a diagram illustrating the ray spacing S in the floating image display device 1. The ray spacing S is defined by an average value based on the sum of the ray spacings s for each of the two rays r1 and r2 when the two rays r1 and r2 are incident on the reflecting element 3 of the floating image display device 1. The two rays r1 and r2 are parallel to each other, and are incident on the reflecting element 3 with a predetermined spacing (spacing between incident rays) in a plan view. The ray spacing S is expressed by equations (2) and (3).

[0045]

[0046]

[0047] In equation (2), the first term represents the ray spacing s for ray r1 in FIG. 7, and the second term represents the ray spacing s for ray r2 in FIG. 7. d is the first spacing G1 between adjacent first reflecting surfaces 51, which was set to 5 mm in the optical simulations shown in FIGS. 8 to 11. φ is the intersection angle between the first reflecting surface 51 and the second reflecting surface 52 in a planar view, and is also the intersection angle between the third reflecting surface 53 and the fourth reflecting surface 54 in a planar view. φ is also referred to as the plane intersection angle. g is a parameter representing the incident positions of rays r1 and r2, and represents the distance from the lattice point LP of the reflecting surface 5 to the position where rays r1 and r2 are incident on the reflecting surface 5. As will be described later, by averaging the ray spacing S with respect to the parameter g, the dependency of the ray spacing S on the incident position can be substantially eliminated. Furthermore, by averaging the ray spacing S with respect to the parameter g, it is possible to substantially eliminate the dependency of the ray spacing S on the spacing between incident rays. α is the angle of incidence of the rays r1 and r2 with respect to the first reflecting surface 51, and β is the angle of intersection between the first reflecting surface 51 and the rays r1 and r2. Note that α is the angle of incidence in a planar view, and β is the angle of intersection in a planar view. α and β satisfy β = 90° - α.

[0048] FIG. 8 shows the relationship between the intersection angle β and the beam spacing S and S ＣIn order to average the ray spacing S with respect to the incident position g, the sum of the ray spacing S when the incident position g is changed in increments of 0.1×d from 0.1×d to 0.9×d is calculated, and the calculated sum is taken as the average ray spacing S (also referred to as the average ray spacing Save). Similarly, each ray spacing S Ｃ is averaged over the incident position g, and the average ray spacing S Ｃ (Average ray spacing S Ｃ ave). Figure 8 shows the relationship between the crossing angle β and the average ray spacing S, S Ｃ In the following, the average ray spacing S and S Ｃ is simply expressed as the ray spacing S, S Ｃ FIG. 8 shows the relationship between the intersection angle β, the beam spacing S (solid line, dashed line, and dashed double-dashed line), and the beam spacing S Ｃ 8, the two-dot chain line indicates the ray spacing S when the plane crossing angle φ is 45°, the one-dot chain line indicates the ray spacing S when the plane crossing angle φ is 50°, and the solid line indicates the ray spacing S when the plane crossing angle φ is 55°.

[0049] As shown in FIG. Ｃ increases monotonically as the crossing angle β increases. Therefore, in the floating image display device C, as the crossing angle β increases, the degradation of the resolution of the floating image F becomes more pronounced. When the crossing angle β is greater than about 1° to 8°, the light ray interval S Ｃ Therefore, the floating image display device 1 can suppress the degradation of the resolution of the floating image F more than the floating image display device C at substantially any crossing angle β. By setting the plane crossing angle φ to 55°, the floating image display device 1 can suppress the degradation of the resolution of the floating image F more than the floating image display device C at substantially all crossing angles β.

[0050] The image light L incident on the reflecting element 3 is diffracted inside the reflecting element 3. Diffraction is caused by the wave properties of light and corresponds to a special case of light scattering (spatial spread of light). For example, if there is an obstacle in the light path, a phenomenon (diffraction) occurs in which light bends around the obstacle. Also, an object with a property of repeating at regular intervals, such as a diffraction grating, diffracts light in a regular diffraction pattern. The diffraction of the image light L occurs when the ray spacings S and S areＣ Therefore, the resolution of the floating image F may be deteriorated. In order to accurately evaluate the resolution of the floating image F, the light ray intervals S and S Ｃ It is necessary to take into account the effect of diffraction of the image light L. Here, the ray spacing S Ｃ The beam spacing S expressed by the formula (2) and the diffraction width Δdiff expressed by the formula (4) are multiplied to obtain the beam spacings S and S Ｃ The effect of diffraction of the image light L is taken into account.

[0051]

[0052]

[0053] In equations (4) and (5), λ is the wavelength of the light rays r1 and r2, and D is the distance (optical path length) between the reflecting element 3 and the eye of the user 7. Furthermore, u(x, y) is the amplitude of the diffracted light, Δdiff is the diffraction width (intensity), A is a constant, wx is the horizontal width of the grating interval, and wy is the vertical width of the grating interval. The grating interval d (in this embodiment, d = 5 mm) is d = wx = wy. The wavelength λ and the distance D are related to the light ray interval S Ｃ and the beam spacing S. In the optical simulations shown in Figures 9 to 11, λ may be a predetermined wavelength selected from 360 to 830 nm in the visible light wavelength range, and in this embodiment, it was set to 550 nm, which is the wavelength of green light. D may be a predetermined distance selected from, for example, 350 mm to 550 mm, and in this embodiment, it was set to 500 mm.

[0054] The minimum grating interval of the reflective element 3 in the conventional floating image display device C shown in FIG. 6 is d, and the minimum grating interval of the reflective element 3 in the floating image display device 1 of this embodiment shown in FIG. 4 is d / (√2). The influence of the diffraction width Δdiff on the resolution of the floating image F is inversely proportional to the minimum grating interval (also referred to as the aperture width a), so the resolution of the reflective element 3 of this embodiment will be slightly deteriorated as the minimum grating interval becomes smaller. If the diffraction width of the reflective element 3 of this embodiment is Δdiffp and the diffraction width of the conventional reflective element 3 is Δdiffc, then Δdiffp = (√2) × (√2) × Δdiffc, and there is an influence of the horizontal width of the grating (√2) and an influence of the vertical width of the grating (√2). As a result, due to the influence of diffraction, the ray interval S of the reflective element 3 of this embodiment is smaller than the ray interval S of the conventional reflective element 3. Ｃ That is, the resolution of the reflecting element 3 of this embodiment is slightly lower than the resolution of the conventional reflecting element 3.

[0055] FIG. 9 shows the relationship between the crossing angle β and the beam spacing S and S Ｃ 9 is a graph showing the relationship between the ray spacing S and the diffraction width Δdiff when the plane crossing angle φ is 45°. Ｃ The two-dot chain line indicates the ray spacing S when the aperture width a is set to d / (√2). Ｃ As shown in Fig. 9, when the diffraction width Δdiff is taken into consideration, when the crossing angle β is about 27° or less, the floating image display device C has a higher resolution of the floating image F than the floating image display device 1. When the crossing angle β exceeds about 27°, the floating image display device 1 has a higher resolution of the floating image F than the floating image display device C.

[0056] In FIG. 9, the ray spacing S and S Ｃ The distance between the rays S and S Ｃ In order to evaluate more accurately, the ray intervals S and S Ｃ (hereinafter, simply referred to as "change rate") must be taken into consideration. Ｃ The rate of change of the ray spacing S, S with respect to the change of the parameter g representing the incident positions of the rays r1 and r2 isＣ When the rate of change is high, the resolution of the floating image F is likely to change due to vibration of the floating image display devices 1, C (i.e., changes in the relative position between the display device 2 and the reflecting element 3), etc., and the user 7 may not be able to view the floating image F with a stable resolution. The rate of change of the ray spacing S is defined by the value obtained by dividing the ray spacing S when the parameter g is 0.1×d by the ray spacing S when the parameter g is 0.9×d. The ray spacing S Ｃ The rate of change of is similarly defined.

[0057] FIG. 10 shows the relationship between the intersection angle β and the beam spacing S and S Ｃ 10 is a graph showing the relationship between the rate of change of the beam spacing S when the plane crossing angle φ is 45°, and the dashed line shows the rate of change of the beam spacing S when the plane crossing angle φ is 45°. Ｃ As shown in FIG. Ｃ The rate of change of the beam spacing S is always 9% when the crossing angle β is in the range of 1° to 39°. The rate of change of the beam spacing S is about 2% when the crossing angle β is in the range of 1° to 18°, and increases monotonically when the crossing angle β is greater than 18°. When the crossing angle β is in the range of 1° to 35°, the rate of change of the beam spacing S is about 1% when the crossing angle β is in the range of 1° to 35°. Ｃ The rate of change is smaller than that of

[0058] FIG. 11 shows the relationship between the crossing angle β, the diffraction width Δdiff, and the ray spacing S and S Ｃ In Fig. 11, the solid line indicates the ray spacing S when the diffraction width Δdiff and the rate of change are taken into consideration when the plane crossing angle φ is 45°, and the dashed line indicates the ray spacing S when the diffraction width Δdiff and the rate of change are taken into consideration. Ｃ The two-dot chain line indicates the ray spacing S taking into consideration the diffraction width Δdiff and the rate of change when the aperture width a is set to d / (√2). Ｃ 11, when the diffraction width Δdiff and the rate of change are taken into consideration, the floating image display device 1 has a higher resolution of the floating image F than the floating image display device C when the crossing angle β is in the range of 1° to 37°. As described above, the floating image display device 1 can improve the resolution of the floating image F compared to the conventional floating image display device C.

[0059] Next, a floating image display device according to another embodiment of the present disclosure will be described. Fig. 12 is a side view showing the configuration of the floating image display device according to another embodiment of the present disclosure, Fig. 13 is an exploded perspective view showing the configuration of the reflective element of the floating image display device of Fig. 12, Fig. 14 is a plan view showing the configuration of the reflective element of the floating image display device of Fig. 12, and Fig. 15 is a plan view showing another example of the reflective element of the floating image display device of Fig. 12.

[0060] The floating image display device 1A of this embodiment is different from the floating image display device 1 in the configuration of the reflective element 3, but has the same configuration as the floating image display device 1 in other respects. Therefore, the same reference symbols as those in the floating image display device 1 are used for the similar configurations, and detailed explanations will be omitted.

[0061] As shown in Fig. 12, the floating image display device 1A includes a display device 2 and a reflective element 3. The reflective element 3 includes a transparent substrate 4 and a reflective surface 5 (shown in Fig. 13). The reflective surface 5 includes a plurality of first reflective surfaces 51, a plurality of second reflective surfaces 52, a plurality of third reflective surfaces 53, and a plurality of fourth reflective surfaces 54.

[0062] The plurality of first reflecting surfaces 51 are located inside the transparent substrate 4 and closer to the incident surface 4a. The plurality of first reflecting surfaces 51 have a parallel array structure PA1. The surface direction of the first reflecting surfaces 51 may be perpendicular or approximately perpendicular to the first surface 4a.

[0063] The plurality of second reflecting surfaces 52 are located closer to the second surface 4b than the plurality of first reflecting surfaces 51. The plurality of second reflecting surfaces 52 have a parallel array structure PA2. The surface direction of the second reflecting surfaces 52 may be perpendicular or approximately perpendicular to the first surface 4a. The plurality of second reflecting surfaces 52 have an array direction different from that of the plurality of first reflecting surfaces 51. As shown in FIG. 14 , the first reflecting surface 51 and the second reflecting surface 52 may intersect at an acute angle in a plan view. The first reflecting surface 51 and the second reflecting surface 52 may intersect at an angle of 45° or more and 55° or less in a plan view.

[0064] The plurality of third reflecting surfaces 53 are located equidistant from the first surface 4a as the plurality of second reflecting surfaces 52. The plurality of second reflecting surfaces 52 and the plurality of third reflecting surfaces 53 may be located equidistant from the second surface 4b. The plurality of third reflecting surfaces 53 have a parallel array structure PA3. The surface direction of the third reflecting surfaces 53 may be perpendicular or approximately perpendicular to the first surface 4a. The plurality of third reflecting surfaces 53 have an array direction different from that of the plurality of second reflecting surfaces 52. As shown in FIG. 14 , the second reflecting surfaces 52 and the third reflecting surfaces 53 may intersect at a right angle or approximately a right angle in a plan view. The second reflecting surfaces 52 and the third reflecting surfaces 53 may intersect at an angle of 89° or more and 91° or less in a plan view.

[0065] The plurality of fourth reflecting surfaces 54 are located closer to the second surface 4b than the plurality of second reflecting surfaces 52 and the plurality of third reflecting surfaces 53. The plurality of fourth reflecting surfaces 54 have a parallel array structure PA4. The surface direction of the fourth reflecting surfaces 54 may be perpendicular or substantially perpendicular to the first surface 4a. The plurality of fourth reflecting surfaces 54 have an array direction different from that of the plurality of third reflecting surfaces 53. As shown in FIG. 14 , the third reflecting surface 53 and the fourth reflecting surface 54 may intersect at an acute angle in a plan view. The third reflecting surface 53 and the fourth reflecting surface 54 may intersect at an angle of 45° or more and 55° or less in a plan view. The fourth reflecting surface 54 extends along the first reflecting surface 51 in a plan view. The fourth reflecting surface 54 may extend parallel or substantially parallel to the first reflecting surface 51 in a plan view. The fourth reflecting surface 54 may overlap the first reflecting surface 51 in a plan view.

[0066] Each of the plurality of first reflecting surfaces 51, the plurality of second reflecting surfaces 52, the plurality of third reflecting surfaces 53, and the plurality of fourth reflecting surfaces 54 may be a parallel array structure PA1, PA2, PA3, PA4 in which a plurality of reflecting layers are arranged in parallel via a long plate-shaped transparent substrate in a direction perpendicular to the reflecting surface 5. In other words, a long plate-shaped transparent substrate may be present between two adjacent reflecting surfaces 5. In this case, the parallel array structures PA1 to PA4 may be configured by forming a metal thin film 6 on one side surface (the surface corresponding to the reflecting surface 5) of the long plate-shaped transparent substrate and stacking a plurality of long plate-shaped transparent substrates in the direction of the side surface.

[0067] The transparent substrate 4 may be configured by stacking in the vertical direction a first parallel array structure PA1 having a plurality of first reflecting surfaces 51, a second parallel array structure PA2 having a plurality of second reflecting surfaces 52, a third parallel array structure PA3 having a plurality of third reflecting surfaces 53, and a fourth parallel array structure PA4 having a plurality of fourth reflecting surfaces 54. In this case, stacking the first to fourth parallel array structures PA1 to PA4 having similar configurations makes it easier to manufacture the transparent substrate 4.

[0068] The long plate-shaped transparent substrate may be configured to contain glass or a transparent resin. The glass may be, for example, low-melting-point glass, sol-gel glass, borosilicate glass, crystallized glass, quartz, soda glass, etc. The transparent resin may be, for example, acrylic resin, epoxy resin, silicone resin, polycarbonate resin, etc.

[0069] Each of the plurality of first reflecting surfaces 51, the plurality of second reflecting surfaces 52, the plurality of third reflecting surfaces 53, and the plurality of fourth reflecting surfaces 54 may be a parallel array structure PA1 to PA4 made of a transparent plate having a reflecting layer in a plurality of mutually parallel grooves or cavities. In this case, the plurality of first reflecting surfaces 51 are made up of a single transparent plate and a plurality of reflecting layers provided on the single transparent plate, which makes it easy to form the plurality of first reflecting surfaces 51. The same is true for the plurality of second reflecting surfaces 52, the plurality of third reflecting surfaces 53, and the plurality of fourth reflecting surfaces 54.

[0070] A method for manufacturing the parallel array structures PA1 to PA4 made of a transparent plate with a reflective layer in a plurality of parallel grooves will be described later. The parallel array structures PA1 to PA4 made of a transparent plate with a reflective layer in a plurality of parallel cavities may also be manufactured by the following manufacturing method. A reflective layer may be formed in a plurality of parallel grooves, and then the grooves may be covered and sealed with a transparent material such as a transparent resin or sol-gel glass, thereby resulting in a configuration in which a reflective layer is present in the cavities.

[0071] The transparent substrate 4 may be configured by stacking a first parallel array structure PA1 having a plurality of first reflecting surfaces 51, a second parallel array structure PA2 having a plurality of second reflecting surfaces 52, a third parallel array structure PA3 having a plurality of third reflecting surfaces 53, and a fourth parallel array structure PA4 having a plurality of fourth reflecting surfaces 54. In this case, by stacking the first to fourth parallel array structures PA1 to PA4 having similar configurations, the transparent substrate 4 can be easily manufactured.

[0072] The transparent plate may be made of glass or a transparent resin. The glass may be any of those described above, and the transparent resin may be any of those described above.

[0073] The floating image display device 1A, like the floating image display device 1, has a wide range of the crossing angle β, and the light beam interval S is determined by taking into account the diffraction width and the rate of change. Ｃ . The floating image display device 1A can improve the resolution of the floating image F compared to the floating image display device C. Furthermore, since the floating image display device 1A has the plurality of second reflecting surfaces 52 and the plurality of third reflecting surfaces 53 located in the same layer (the second layer 42a), the thickness of the transparent substrate 4 can be made thinner compared to the floating image display device 1. The floating image display device 1A can reduce the loss of the image light L inside the transparent substrate 4, thereby improving the utilization efficiency of the image light L. Therefore, the floating image display device 1A can suppress a decrease in the brightness of the floating image F caused by the loss of the image light L. Alternatively, the floating image display device 1A can reduce the brightness of the image displayed on the display surface 2a while maintaining sufficient brightness of the floating image F, thereby reducing the power consumption of the floating image display device 1.

[0074] The floating image display device 1A may be configured such that the first reflecting surface 51 and the second reflecting surface 52 intersect at 45° in a plan view, the first reflecting surface 51 and the third reflecting surface 53 intersect at 45° in a plan view, and the first reflecting surface 51 and the fourth reflecting surface 54 overlap in a plan view. In this case, it is possible to reduce the possibility that the image light L is not reflected sequentially by the first reflecting surface 51, the second reflecting surface 52, the third reflecting surface 53, and the fourth reflecting surface 54. As a result, it is possible to prevent the image light L from becoming stray light, and to prevent the stray light from being visually recognized by the user 7 as a ghost image.

[0075] The multiple first reflecting surfaces 51 are arranged at a predetermined first interval G1 in a plan view. The multiple second reflecting surfaces 52 are arranged at a predetermined second interval G2 in a plan view. The multiple third reflecting surfaces 53 are arranged at a predetermined third interval G3 in a plan view. The multiple fourth reflecting surfaces 54 are arranged at a predetermined fourth interval G4 in a plan view. The first interval G1 and the fourth interval G4 may be the same or approximately the same. The second interval G2 and the third interval G3 may be the same or approximately the same.

[0076] The transparent substrate 4 may have a layered structure in which a first layer 41a, a second layer 42a, and a third layer 43a are layered in this order. The first layer 41a includes an incident surface 4a, and the third layer 43a includes an exit surface 4b. A plurality of first reflecting surfaces 51 are located within the first layer 41a. A plurality of second reflecting surfaces 52 and a plurality of third reflecting surfaces 53 are located within the second layer 42a. A plurality of fourth reflecting surfaces 54 are located within the third layer 43a.

[0077] The first layer 41a, the second layer 42a, and the third layer 43a may each have a thickness of, for example, approximately 0.5 to 10 mm, or approximately 1.5 to 5.0 mm. The thicknesses of the first layer 41a, the second layer 42a, and the third layer 43a may be the same or different from one another. For example, the second layer 42a may be thicker than the first layer 41a and the third layer 43a. In this case, the possibility that the image light L reflected by one of the second reflecting surface 52 and the third reflecting surface 53 is reflected by the fourth reflecting surface 54 without being reflected by the other of the second reflecting surface 52 and the third reflecting surface 53 is reduced, thereby increasing the possibility that the image light L is reflected by both the second reflecting surface 52 and the third reflecting surface 53. As a result, the ray spacing S can be reduced, and the resolution of the floating image F can be improved.

[0078] The floating image display device 1, 1A may be configured such that the first interval G1 is greater than the second interval G2 (G1>G2) and greater than the third interval G3 (G1>G3) (see FIGS. 4 and 14). In this case, the image light L reflected by the first reflecting surface 51 can be prevented from being reflected again by the first reflecting surface 51 before being reflected by the second reflecting surface 52 or the third reflecting surface 53. As a result, the image light L emitted from the reflecting element 3 can be prevented from becoming stray light, and the stray light can be prevented from being visually perceived by the user 7 as a ghost image. Furthermore, by reflecting the image light L reflected by the first reflecting surface 51 by the second reflecting surface 52, the reflectivity of the image light L emitted from the reflecting element 3 can be improved (i.e., the ray interval S can be reduced), thereby improving the resolution of the floating image F. The first interval G1 may be, for example, approximately 0.1 to 1.0 mm. The second gap G2 and the third gap G3 may be approximately 1 / √2 times the first gap G1. The second gap G2 and the third gap G3 may be, for example, approximately 0.07 to 0.70 mm.

[0079] 4 and 14, the floating image display device 1, 1A may be configured such that the first reflecting surface 51 and the fourth reflecting surface 54 overlap in a planar view. In this case, the traveling direction of the image light L emitted from the reflecting element 3 can be made parallel or approximately parallel to the traveling direction of the image light L incident on the reflecting element 3 in a planar view. In other words, the image light L can be made more easily reflected retrogradely in a planar view. As a result, the ray spacing S can be made smaller, and the resolution of the floating image F can be further improved.

[0080] As shown in FIG. 15 , the floating image display device 1, 1A may be configured such that the first reflecting surface 51 and the fourth reflecting surface 54 are offset in the arrangement direction of the plurality of fourth reflecting surfaces 54 (the left-right direction in FIG. 15 ) so that the ray spacing S becomes smaller in a planar view. In other words, the fourth reflecting surface 54 may be offset relative to the first reflecting surface 51 in the arrangement direction of the plurality of fourth reflecting surfaces 54 so that the ray spacing S becomes smaller in a planar view. The offset width may be approximately 0.01 mm to 0.05 mm, but is not limited to this range. In this case, it is possible to adjust the optical path length of the image light L from the third reflecting surface 53 to the fourth reflecting surface 54 so that the image light L is retroreflected in a planar view. As a result, the ray spacing S can be made smaller, and the resolution of the floating image F can be further improved. Although Figure 15 shows a case where the transparent substrate 4 has a four-layer laminated structure (see Figures 2 and 3), the effect of the misalignment between the first reflecting surface 51 and the fourth reflecting surface 54 is the same when the transparent substrate 4 has a three-layer laminated structure (see Figures 12 and 13).

[0081] The reflective element 3 of the floating image display device 1 can be fabricated, for example, as follows. First, a flat-plate-shaped first layer precursor (precursor of the first layers 41, 41a) made of a transparent material (the above-mentioned transparent resin or transparent glass) is prepared. Next, multiple grooves are formed in the first layer precursor. Each of the multiple grooves is recessed in the thickness direction from the main surface of the first layer precursor, extends in a predetermined direction perpendicular to the thickness direction, and has an intersecting surface that intersects with the main surface of the first layer precursor. When viewed in the predetermined direction, the grooves may have, for example, a triangular or rectangular shape. Next, a metal thin film 6 is formed on the intersecting surface, and then a transparent material is filled into the grooves, thereby fabricating the first layer 41 having the reflective surface 5 (multiple first reflective surfaces 51) located therein. Note that the metal thin film 6 may be left exposed without filling each groove with a transparent material. Next, the second layer 42, the third layer 43, and the fourth layer 44, each having the reflective surface 5 located therein, are sequentially fabricated on the first layer 41, thereby fabricating the reflective element 3. Alternatively, the first layer 41, the second layer 42, the third layer 43, and the fourth layer 44, each having the reflective surface 5 located therein, may be fabricated separately and then stacked to fabricate the reflective element 3. The reflective element 3 of the floating image display device 1A can be fabricated in the same manner.

[0082] According to the floating image display device of the present disclosure, the resolution of the floating image can be improved.

[0083] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0084] The floating image display device of the present disclosure can be implemented with the following configurations (1) to (20).

[0085] (1) A floating image display device comprising: a display device; and a reflective element that displays image light emitted from the display device as a floating image of a real image by reflecting the image light in a direction different from the direction toward the display device, wherein the reflective element includes a transparent substrate having a first surface and a second surface facing each other, and reflective surfaces located inside the transparent substrate and arranged parallel to each other at intervals whose surface directions intersect with the first surface, wherein the reflective surfaces include: a plurality of first reflective surfaces located closer to the first surface; a plurality of second reflective surfaces and a plurality of third reflective surfaces that are each located closer to the second surface than the plurality of first reflective surfaces and have an arrangement direction different from that of the plurality of second reflective surfaces; and a plurality of fourth reflective surfaces located closer to the second surface than the plurality of second reflective surfaces and the plurality of third reflective surfaces and have an arrangement direction different from that of the plurality of third reflective surfaces, wherein the image light travels along an optical path in which it is sequentially reflected by the first reflective surface, the second reflective surface, the third reflective surface, and the fourth reflective surface.

[0086] (2) The floating image display device according to (1), wherein the third reflecting surfaces are located closer to the second surface than the second reflecting surfaces, and the fourth reflecting surface extends along the first reflecting surface in a plan view.

[0087] (3) The floating image display device described in (2) above, wherein the first reflecting surface and the second reflecting surface intersect at an acute angle in a planar view, the second reflecting surface and the third reflecting surface intersect at a right angle in a planar view, and the third reflecting surface and the fourth reflecting surface intersect at an acute angle in a planar view.

[0088] (4) A floating image display device according to (2) or (3), wherein the distance between adjacent first reflecting surfaces in a planar view is a first distance, the distance between adjacent second reflecting surfaces in a planar view is a second distance, and the distance between adjacent third reflecting surfaces in a planar view is a third distance, the first distance is larger than the second distance and the first distance is larger than the third distance.

[0089] (5) The floating image display device according to any one of (2) to (4) above, wherein the first reflecting surface and the fourth reflecting surface overlap in a plan view.

[0090] (6) The floating image display device according to any one of (2) to (4) above, wherein the first reflecting surface and the fourth reflecting surface are offset from each other in a plan view in the arrangement direction of the plurality of fourth reflecting surfaces.

[0091] (7) The floating image display device according to (1), wherein the plurality of third reflecting surfaces are positioned at equal distances from the plurality of second reflecting surfaces and the first surface, and the fourth reflecting surface extends along the first reflecting surface in a planar view.

[0092] (8) The floating image display device described in (7) above, wherein the first reflecting surface and the second reflecting surface intersect at an acute angle in a planar view, the second reflecting surface and the third reflecting surface intersect at a right angle in a planar view, and the third reflecting surface and the fourth reflecting surface intersect at an acute angle in a planar view.

[0093] (9) A floating image display device as described in (7) or (8) above, wherein when the distance between adjacent first reflecting surfaces in a planar view is a first distance, the distance between adjacent second reflecting surfaces in a planar view is a second distance, and the distance between adjacent third reflecting surfaces in a planar view is a third distance, the first distance is larger than the second distance and the first distance is larger than the third distance.

[0094] (10) The floating image display device according to any one of (7) to (9), wherein the first reflecting surface and the fourth reflecting surface overlap in a plan view.

[0095] (11) The floating image display device according to any one of (7) to (9), wherein the first reflecting surface and the fourth reflecting surface are offset from each other in a plan view in the arrangement direction of the plurality of fourth reflecting surfaces.

[0096] (12) The floating image display device according to any one of (1) to (11) above, wherein the display device is located on the first surface side of the transparent substrate, and the floating image is located on the second surface side of the transparent substrate.

[0097] (13) The floating image display device according to (12), wherein the display device and the floating image are positioned to overlap in a plan view.

[0098] (14) The floating image display device according to any one of (1) to (13), wherein the intersection angle between the first surface and the surface directions of the first reflecting surface, the second reflecting surface, the third reflecting surface, and the fourth reflecting surface is 80° to 100°.

[0099] (15) A floating image display device described in any one of (1) to (14) above, wherein each of the plurality of first reflecting surfaces, the plurality of second reflecting surfaces, the plurality of third reflecting surfaces, and the plurality of fourth reflecting surfaces is a parallel arrangement structure in which a plurality of reflecting layers are arranged in parallel via a long plate-shaped transparent substrate in a direction perpendicular to the reflecting surface.

[0100] (16) The floating image display device described in (15) above, wherein the transparent substrate is formed by stacking a first parallel array structure having the plurality of first reflecting surfaces, a second parallel array structure having the plurality of second reflecting surfaces, a third parallel array structure having the plurality of third reflecting surfaces, and a fourth parallel array structure having the plurality of fourth reflecting surfaces.

[0101] (17) The floating image display device according to (15) or (16) above, wherein the long plate-shaped transparent substrate contains glass or a transparent resin.

[0102] (18) A floating image display device described in any one of (1) to (14) above, wherein each of the plurality of first reflecting surfaces, the plurality of second reflecting surfaces, the plurality of third reflecting surfaces, and the plurality of fourth reflecting surfaces is a parallel array structure made of a transparent plate having a reflecting layer in a plurality of grooves or cavities parallel to each other.

[0103] (19) The floating image display device described in (18) above, wherein the transparent substrate is formed by stacking a first parallel array structure having the plurality of first reflecting surfaces, a second parallel array structure having the plurality of second reflecting surfaces, a third parallel array structure having the plurality of third reflecting surfaces, and a fourth parallel array structure having the plurality of fourth reflecting surfaces.

[0104] (20) The floating image display device according to (18) or (19) above, wherein the transparent plate includes glass or transparent resin. Industrial application fields

[0105] The floating image display device of the present disclosure allows touchless operation of floating images, and as a result can be used in various product fields such as, but not limited to, a communication device for conversation, communication, etc., accompanied by a floating image, a medical interview device in which a doctor interviews a patient through a floating image, a navigation device and operation control device for vehicles such as automobiles, an order placement and reception device and cash register device for stores, etc., an operation panel for buildings, elevators, etc., a learning device for teaching or taking classes accompanied by a floating image, an office machine for business communication, instructions, etc. accompanied by a floating image, an amusement machine for playing games accompanied by a floating image, a projection device for projecting images onto the ground, walls, etc. at amusement parks, game centers, etc., a simulator device for conducting simulation experiments, etc., using floating images at universities, medical institutions, etc., a large display that displays prices, etc. at markets, stock exchanges, etc., and a video viewing device for viewing images of floating images.

[0106] 1, 1A Floating image display device 2 Display device 2a Display surface 3 Reflective element 4 Transparent substrate 4a 1st surface (incident surface) 4b 2nd surface (output surface) 41, 41a 1st layer 42, 42a 2nd layer 43, 43a 3rd layer 44 4th layer 5 Reflective surface (lattice-shaped reflective surface) 51 1st reflective surface 52 2nd reflective surface 53 Third reflective surface 54 Fourth reflective surface 55 Fifth reflective surface 56 Sixth reflective surface 6 Metal thin film 7 User

Claims

1. A floating image display device comprising a display device and a reflection element that displays a real image as a floating image by reflecting image light emitted from the display device in a direction different from the direction toward the display device, wherein the reflection element includes a transparent substrate having a first surface and a second surface facing each other, and reflection surfaces located inside the transparent substrate and arranged in parallel with each other at intervals intersecting the first surface in a plane direction, and the reflection surfaces include a plurality of first reflection surfaces located closer to the first surface, a plurality of second reflection surfaces respectively located closer to the second surface side than the plurality of first reflection surfaces and having an arrangement direction different from that of the plurality of first reflection surfaces, a plurality of third reflection surfaces having an arrangement direction different from that of the plurality of second reflection surfaces, and a plurality of fourth reflection surfaces located closer to the second surface than the plurality of second reflection surfaces and the plurality of third reflection surfaces and having an arrangement direction different from that of the plurality of third reflection surfaces, and the image light travels along an optical path sequentially reflected by the first reflection surface, the second reflection surface, the third reflection surface, and the fourth reflection surface.

2. The floating image display device according to claim 1, wherein the plurality of third reflection surfaces are located closer to the second surface side than the plurality of second reflection surfaces, and the fourth reflection surface extends along the first reflection surface in a plan view.

3. The floating image display device according to claim 2, wherein the first reflection surface and the second reflection surface intersect at an acute angle in a plan view, the second reflection surface and the third reflection surface intersect at a right angle in a plan view, and the third reflection surface and the fourth reflection surface intersect at an acute angle in a plan view.

4. When the interval between adjacent first reflection surfaces in a plan view is defined as a first interval, the interval between adjacent second reflection surfaces in a plan view is defined as a second interval, and the interval between adjacent third reflection surfaces in a plan view is defined as a third interval, the first interval is larger than the second interval and the first interval is larger than the third interval. The floating image display device according to claim 2.

5. The floating image display device according to any one of claims 2 to 4, wherein the first reflection surface and the fourth reflection surface overlap in a plan view.

6. The floating image display device according to any one of claims 2 to 4, wherein the first reflection surface and the fourth reflection surface are shifted in the arrangement direction of the plurality of fourth reflection surfaces in a plan view.

7. The plurality of third reflecting surfaces are located at an equal distance from the plurality of second reflecting surfaces and the first surface, and the fourth reflecting surface extends along the first reflecting surface in a plan view. The floating image display device according to claim 1.

8. The first reflecting surface and the second reflecting surface intersect at an acute angle in a plan view, the second reflecting surface and the third reflecting surface intersect at a right angle in a plan view, and the third reflecting surface and the fourth reflecting surface intersect at an acute angle in a plan view. The floating image display device according to claim 7.

9. When the distance between adjacent first reflecting surfaces in a plan view is defined as a first interval, the distance between adjacent second reflecting surfaces in a plan view is defined as a second interval, and the distance between adjacent third reflecting surfaces in a plan view is defined as a third interval, the first interval is larger than the second interval, and the first interval is larger than the third interval. The floating image display device according to claim 7.

10. The first reflecting surface and the fourth reflecting surface overlap in a plan view. The floating image display device according to any one of claims 7 to 9.

11. The first reflecting surface and the fourth reflecting surface are shifted in the arrangement direction of the plurality of fourth reflecting surfaces in a plan view. The floating image display device according to any one of claims 7 to 9.

12. The display device is located on the side of the first surface of the transparent substrate, and the floating image is located on the side of the second surface of the transparent substrate. The floating image display device according to any one of claims 1 to 11.

13. The display device and the floating image are in an overlapping position in a plan view. The floating image display device according to claim 12.

14. The intersection angle between each surface direction of the first reflecting surface, the second reflecting surface, the third reflecting surface, and the fourth reflecting surface and the first surface is 80° to 100°. The floating image display device according to any one of claims 1 to 13.

15. Each of the plurality of first reflecting surfaces, the plurality of second reflecting surfaces, the plurality of third reflecting surfaces, and the plurality of fourth reflecting surfaces is a parallel arrangement structure in which a plurality of reflecting layers are arranged in parallel through a long plate-shaped transparent substrate in a direction perpendicular to the reflecting surface. The floating image display device according to any one of claims 1 to 14.

16. The floating image display device according to claim 15, wherein the transparent substrate is formed by laminating a first parallel array structure including the plurality of first reflection surfaces, a second parallel array structure including the plurality of second reflection surfaces, a third parallel array structure including the plurality of third reflection surfaces, and a fourth parallel array structure including the plurality of fourth reflection surfaces.

17. The floating image display device according to claim 15 or 16, wherein the long plate-shaped transparent substrate includes glass or a transparent resin.

18. The floating image display device according to any one of claims 1 to 14, wherein each of the plurality of first reflection surfaces, the plurality of second reflection surfaces, the plurality of third reflection surfaces, and the plurality of fourth reflection surfaces is a parallel array structure formed of a transparent plate having a reflection layer in a plurality of groove portions or cavity portions parallel to each other.

19. The floating image display device according to claim 18, wherein the transparent substrate is formed by laminating a first parallel array structure including the plurality of first reflection surfaces, a second parallel array structure including the plurality of second reflection surfaces, a third parallel array structure including the plurality of third reflection surfaces, and a fourth parallel array structure including the plurality of fourth reflection surfaces.

20. The floating image display device according to claim 18 or 19, wherein the transparent plate includes glass or a transparent resin.

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