Floating image display device and moving body

Abstract

A floating image display device according to the present disclosure comprises a display unit and an optical system. The optical system has at least a first concave mirror and a second concave mirror. The first concave mirror faces the display unit at an inclination. The second concave mirror faces the first concave mirror at an inclination and forms a floating real image. A deviation between the geometric center and the optical center on a first reflection surface of the first concave mirror is larger than a deviation between the geometric center and the optical center on a second reflection surface of the second concave mirror.

Description

Floating image display device and moving body

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

[0002] A floating image display device described in Patent Document 1 is known.

[0003] Special Publication No. 2002-511596

[0004] The floating image display device of the present disclosure comprises a display unit, an optical system having at least a first concave mirror that faces the display unit at an angle, and a second concave mirror that faces the first concave mirror at an angle and forms a floating image of a real image, wherein Δd1 is the deviation between the geometric center and the optical center on a first reflecting surface of the first concave mirror, and Δd2 is the deviation between the geometric center and the optical center on a second reflecting surface of the second concave mirror, and Δd1>Δd2.

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

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

[0024] FIG. 2 is a front view of a first concave mirror, explaining the geometric center of the first concave mirror.

[0025] FIG. 3 is a front view of a first concave mirror, explaining the geometric center of the first concave mirror.

[0026] FIG. 4 is a side view of a first concave mirror, explaining the optical center and curvature of the first concave mirror.

[0027] FIG. 5 is a side view showing a main configuration of a floating image display device, explaining the optical path of light in the floating image display device of FIG. 1.

[0028] FIG. 6 is a graph showing the relationship between Δd1, Δd2, Δd3 and the distortion of a floating image in a first direction.

[0029] FIG. 7 is a graph showing the relationship between Δd1, Δd2, Δd3 and the distortion of a floating image in a second direction.

[0029] FIG. 8 is a graph showing the relationship between Δd1, Δd2, Δd3 and the curvature of field of a floating image.

[0029] FIG. 9 is a side view of a floating image, explaining the curvature of field of the floating image. 15 is a front view of a floating image showing a simulation result of a floating image viewed by a user of the floating image display device of FIG. 1. FIG. 16 is a front view of a floating image showing a simulation result of a floating image viewed by a user of the floating image display device of FIG. 1. FIG. 17 is a front view of a floating image showing a simulation result of a floating image viewed by a user of the floating image display device of FIG. 1. FIG. 18 is a front view of a floating image showing a simulation result of a floating image viewed by a user of the floating image display device of FIG. 1. FIG. 19 is a side view showing a configuration of a main part of a floating image display device according to another embodiment of the present disclosure. FIG. 19 is a side view showing a configuration of a main part of a floating image display device, illustrating the optical path of light in the floating image display device of FIG. 15. FIG. 20 is a graph showing the relationship between Δd1 and Δd2 and the distortion of a floating image in a second direction. FIG. 21 is a graph showing the relationship between Δd1 and Δd2 and the field curvature of a floating image. FIG. 22 is a diagram showing a schematic configuration of a moving body according to an embodiment of the present disclosure.

[0006] Patent Document 1 describes a floating image display device that allows a viewer to visually recognize an image of an object as a floating image by reflecting light coming from the object with first and second concave mirrors.

[0007] There is a demand for reducing the size of floating image display devices, and there is also a demand for improving the display quality of floating image display devices.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The figures referred to below illustrate major components of a floating image display device and a moving body according to embodiments. For example, the floating image display device according to embodiments may include well-known components such as an optical system holding member and a housing, which are not shown. The figures referred to below are schematic, and the dimensional ratios and the like in the figures do not necessarily correspond to those in reality. In this specification, a Cartesian coordinate system XYZ is defined in some figures for convenience. The X-axis direction is also referred to as the first direction or width direction. The Y-axis direction is also referred to as the second direction or height direction. The Z-axis direction is also referred to as the third direction or depth direction. In the description of the embodiments below, the positive direction of the Y-axis direction is defined as upward, and terms such as upper end and lower end may be used. The height direction may be the vertical direction (i.e., the direction of gravity), but is not limited to the vertical direction and may be a direction intersecting the vertical direction.

[0009] 1 to 14 are diagrams or graphs illustrating a floating image display device according to an embodiment of the present disclosure.

[0010] 1, the floating image display device 1 of this embodiment includes a display unit 2 and an optical system 3. The floating image display device 1 displays an image on the display unit 2, and forms light of the image (also called image light) L in the air by the optical system 3, allowing a user 5 to view the image as a real floating image F. The optical system 3 may enlarge and form an image of the image displayed on the display unit 2 at a magnification of 1x or more, or may enlarge and form an image at a magnification of 2x or more.

[0011] The display unit 2 has a display surface 2a, and displays an image formed on the display surface 2a as a floating image F. In other words, the display unit 2 emits light L that is formed as a floating image F from the display surface 2a.

[0012] The display unit 2 may be configured as 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 of the backlight may be, for example, a light-emitting diode (LED) element, a cold cathode fluorescent lamp, a halogen lamp, a xenon lamp, etc.

[0013] 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.

[0014] 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.

[0015] The display unit 2 is not limited to a transmissive display device, and may be configured as a self-luminous display device. A self-luminous display device has a plurality of light-emitting elements arranged two-dimensionally. The light-emitting elements may be, for example, LED elements, organic electroluminescence (OEL) elements, organic light-emitting diode (OLED) elements, semiconductor laser (laser diode) elements, etc.

[0016] The optical system 3 has at least a first concave mirror 31 and a second concave mirror 32. The first concave mirror 31 faces the display unit 2 at an angle. The second concave mirror 32 faces the first reflecting mirror 31 at an angle.

[0017] The first concave mirror 31 has a first reflecting surface 31 a that is a concave surface. The first concave mirror 31 reflects the light L emitted from the display unit 2 in a direction different from the direction toward the display unit 2.

[0018] The second concave mirror 32 has a concave second reflecting surface 32 a. The second concave mirror 32 reflects the light L reflected by the first concave mirror 31 in a direction different from the direction toward the first concave mirror 31, and forms a floating image F of a real image.

[0019] In this embodiment, the optical system 3 further includes a convex mirror 33. The convex mirror 33 has a convex third reflecting surface 33a. The convex mirror 33 is located in the optical path of light L between the first concave mirror 31 and the second concave mirror 32. The convex mirror 33 reflects the light L reflected by the first concave mirror 31 in a direction toward the second concave mirror 32. Therefore, in this embodiment, the second concave mirror 32 reflects the light L reflected by the convex mirror 33 in a direction different from the direction toward the convex mirror 33, forming a floating real image F. Hereinafter, when the first reflecting surface 31a, the second reflecting surface 32a, and the third reflecting surface 33a are not to be distinguished from one another, they may be simply referred to as "reflecting surfaces 31a, 32a, 33a."

[0020] The first concave mirror 31 may be a free-form concave mirror whose first reflecting surface 31 a is defined by a free-form surface. The second concave mirror 32 may be a free-form concave mirror whose second reflecting surface 32 a is defined by a free-form surface. The convex mirror 33 may be a free-form convex mirror whose third reflecting surface 33 a is defined by a free-form surface.

[0021] The free-form surfaces defining the first reflecting surface 31 a, the second reflecting surface 32 a, and the third reflecting surface 33 a may be XY polynomial surfaces (also called SPS XYP surfaces) defined by the following formulas (1) and (2). The XY polynomial surfaces are expanded into polynomials of up to tenth order that are added to the reference conic surface. Therefore, in formulas (1) and (2), the sum of m and n is 10 or less. In formula (1), z is the sag of the surface parallel to the z-axis (also called the optical axis), c is the vertex curvature, and r is the radial distance (i.e., r ２ = x ２ +y ２), k is the conic constant, and C ｊ is a monomial x ｍ y ｎ is the coefficient of

[0022] The first concave mirror 31, the second concave mirror 32, and the convex mirror 33 may be aspherical mirrors. In other words, the first reflecting surface 31 a, the second reflecting surface 32 a, and the third reflecting surface 33 a may be defined by a quadric surface such as a paraboloid, an ellipsoid, or a hyperboloid.

[0023] The first concave mirror 31 has an optical center OC1. The optical center OC1 of the first concave mirror 31 may be the vertex of the curvature of the first reflecting surface 31a. If the first reflecting surface 31a is a free-form surface defined by equations (1) and (2), the vertex of the curvature of the first reflecting surface 31a may be the origin (x = y = z = 0) of the free-form surface. If the first reflecting surface 31a is defined by a quadric surface, the vertex of the curvature of the first reflecting surface 31a may be the vertex of the quadric surface.

[0024] The second concave mirror 32 has an optical center OC2, and the convex mirror 33 has an optical center OC3. The optical center OC2 of the second concave mirror 32 and the optical center OC3 of the convex mirror 33 are defined in the same manner as the optical center OC1 of the first concave mirror 31. Hereinafter, when the optical centers OC1, OC2, and OC3 are not to be distinguished from one another, they may be simply referred to as the "optical center OC."

[0025] The optical center OC1 may be a minute area on the first reflecting surface 31a that is a flat surface, or may be a point located within this minute area. The minute area may have a maximum width of approximately 10 mm or less. In this case, the increase in distortion of the floating image F can be reduced. The maximum width of the minute area may be approximately 0.1 mm to 10 mm, but is not limited to this range. Note that "to" means "to," as applied hereinafter. The maximum width of the minute area may be, for example, the diameter if the minute area is circular; the major axis if the minute area is elliptical; the length of one side or the length of the diagonal if the minute area is square; or the length of the long side or the length of the maximum diagonal if the minute area is rectangular. Furthermore, if the optical center OC1 is a point located within the minute area, the optical center OC1 may be the center point of the minute area. The same applies to the optical centers OC2 and OC3.

[0026] The first concave mirror 31 has a geometric center GC1. The geometric center GC1 of the first concave mirror 31 can be determined as follows. The tangent plane of the first reflecting surface 31a at the optical center OC1 is defined as tangent plane T (see FIG. 5). Each of FIGS. 2 to 4 shows an example of the first reflecting surface 31a viewed from the normal direction of the tangent plane T. The geometric center GC1 of the first reflecting surface 31a may be the centroid (also referred to as the center of gravity) of the first reflecting surface 31a when viewed from the normal direction of the tangent plane T. The normal direction of the tangent plane T coincides with the optical axis direction (z-axis direction) in equation (1).

[0027] The geometric center GC1 may be a minute region on the first reflecting surface 31a that is a flat surface, or may be a point located within this minute region. The minute region may have a maximum width of approximately 10 mm or less. In this case, it is possible to reduce the increase in distortion of the floating image F. The maximum width of the minute region may be approximately 0.1 mm to 10 mm, but is not limited to this range. For example, the maximum width of the minute region may be the diameter if the minute region is circular, the major axis if the minute region is elliptical, the length of one side or the length of the diagonal if the minute region is square, or the length of the long side or the length of the maximum diagonal if the minute region is rectangular. Furthermore, if the geometric center GC1 is a point located within the minute region, the geometric center GC1 may be the center point of the minute region. The same applies to the geometric centers GC2 and GC3.

[0028] As shown in Fig. 2, when the first reflecting surface 31a is circular when viewed from the normal direction of the tangent plane T, the geometric center GC1 coincides with the center of the circle. As shown in Fig. 3, when the first reflecting surface 31a is rectangular (square or oblong) when viewed from the normal direction of the tangent plane T, the geometric center GC1 coincides with the intersection of two diagonals of the rectangle. As shown in Fig. 4, when the first reflecting surface 31a is a hexagon that is approximately rectangular when viewed from the normal direction of the tangent plane T, the geometric center GC1 may be any point within a quadrangular region Q surrounded by the four diagonals of the hexagon, or may be the centroid of the quadrangular region Q.

[0029] Although tangent plane T is not an actual surface, it can be clearly illustrated in a design drawing displayed on a display device of a personal computer (PC) terminal using computer-aided design (CAD) software or the like. Hereinafter, viewing first reflecting surface 31a of first concave mirror 31 from the normal direction of tangent plane T may be referred to as a "front view." The same applies to the front view of second concave mirror 32 and convex mirror 33.

[0030] The second concave mirror 32 has a geometric center GC2, and the convex mirror 33 has a geometric center GC3. The geometric center GC2 of the second concave mirror 32 and the geometric center GC3 of the convex mirror 33 are defined in the same manner as the geometric center GC1 of the first concave mirror 31. Hereinafter, when the geometric centers GC1, GC2, and GC3 are not to be distinguished from one another, they may be simply referred to as the "geometric center GC."

[0031] As shown in FIG. 1, the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 may be positioned at different heights. The position of the first concave mirror 31 may be the position of the geometric center GC1 of the first reflecting surface 31a. The same applies to the second concave mirror 32 and the convex mirror 33. As shown in FIG. 1, the optical system 3 may be configured so that the upper end of the first reflecting surface 31a is located between the upper and lower ends of the third reflecting surface 33a, and the upper end of the third reflecting surface 33a is located between the upper and lower ends of the second reflecting surface 32a. This makes it possible to reduce the height dimension of the floating image display device 1.

[0032] The geometric center GC1 and optical center OC1 of the first concave mirror 31 do not coincide with each other, but rather differ in position, which difference in position is referred to as a deviation. The same applies to the second concave mirror 32 and the convex mirror 33. In this specification, the amount of decentering (also referred to as the amount of positional difference) of the optical center OC1 from the geometric center GC1 of the first concave mirror 31 is referred to as deviation Δd1, the amount of decentering of the optical center OC2 from the geometric center GC2 of the second concave mirror 32 is referred to as deviation Δd2, and the amount of decentering of the optical center OC3 from the geometric center GC3 of the convex mirror 33 is referred to as deviation Δd3. Hereinafter, when there is no need to distinguish between the deviations Δd1, Δd2, and Δd3, they may be simply referred to as "deviation Δd."

[0033] The deviation Δd may be the shortest distance along the reflecting surface 31 a, 32 a, 33 a between the geometric center GC and the optical center OC. The deviation Δd may also be the straight-line distance between the geometric center GC and the optical center OC. When the curvature of the region including the geometric center GC and the optical center OC on the reflecting surface 31 a, 32 a, 33 a is relatively small, the straight-line distance between the geometric center GC and the optical center OC approximately coincides with the shortest distance along the reflecting surface 31 a, 32 a, 33 a between the geometric center GC and the optical center OC.

[0034] The deviation Δd can be set, for example, by the following operation. The optical center OC1 of the first reflecting surface 31a is the vertex of the curvature of the first reflecting surface 31a, the first concave mirror 31 is a free-form concave mirror, and the optical center OC1 of the first reflecting surface 31a is the origin of the free-form surface. The same applies to the second concave mirror 32. The free-form surface can be expressed, for example, by the above formulas (1) and (2). In formula (1), if z = f(x, y), the coordinates of the origin of the free-form surface are (x, y, z) = (0, 0, f(0, 0) = 0). Using this origin as a starting point, the free-form surface can be calculated and formed as a collection of three-dimensional coordinate data in three-dimensional space based on formulas (1) and (2). Then, based on the collection of three-dimensional coordinate data, a design drawing can be clearly illustrated on a display device of a personal computer (PC) terminal using computer-aided design (CAD) program software, etc. Furthermore, a free-form concave mirror can be manufactured by, for example, cutting a metal plate such as an aluminum plate using numerical control based on the design drawing.

[0035] For example, to configure the apex of the curvature of first reflecting surface 31 a of first concave mirror 31 to be closer to display unit 2 from the geometric center GC1 of first reflecting surface 31 a (closer to the bottom end of first reflecting surface 31 a in FIG. 1 ), the number of coordinates from the origin to the top end of first reflecting surface 31 a is set to be greater than the number of coordinates from the origin to the bottom end of first reflecting surface 31 a, relative to the coordinates of the origin (0,0,0). For example, if the direction from the origin toward the top end of first reflecting surface 31 a coincides with the positive (+) direction of the y-axis in equation (1), the magnitude relationship between the number of y-coordinates in the three-dimensional coordinate data from the origin to the top end of first reflecting surface 31 a and the number of y-coordinates in the three-dimensional coordinate data from the origin to the bottom end of first reflecting surface 31 a may be set as described above. For example, if the distance between a certain y coordinate and its adjacent y coordinate in the three-dimensional coordinate data is 100 μm (0.1 mm), a deviation Δd of 1 mm corresponds to a difference in the number of 10 y coordinates.

[0036] The surface shape of the first reflecting surface 31a may be measured as follows. For example, a rod-shaped, needle-shaped, or other contact probe whose tip contacts the first reflecting surface 31a is repeatedly scanned along the x direction of the first reflecting surface 31a, and the displacement of the tip of the contact probe in the z direction is measured, thereby measuring the surface shape of the first reflecting surface 31a in the x direction. When repeatedly scanning along the x direction, for example, the scan may be shifted by approximately 1 μm to 10 mm in the y direction for each scan. That is, the interval in the y direction between a certain scan and the next scan may be approximately 1 μm to 10 mm, but is not limited to this range. Furthermore, a similar method may be used to repeatedly scan the first reflecting surface 31a along the y direction multiple times. This allows the entire surface shape of the first reflecting surface 31a, i.e., the three-dimensional surface shape, to be measured.

[0037] The surface shape of the first reflecting surface 31a may also be measured as follows. The first reflecting surface 31a is irradiated with electromagnetic waves, and the irradiation position of the electromagnetic waves on the first reflecting surface 31a is repeatedly scanned, for example, along the x direction of the first reflecting surface 31a. The time difference between the start of the electromagnetic wave irradiation and the reception of the reflected wave is measured, thereby measuring the surface shape of the first reflecting surface 31a in the x direction. When scanning repeatedly along the x direction, the same procedure as described above may be used. When scanning repeatedly along the y direction, the same procedure may be used. This allows the entire surface shape of the first reflecting surface 31a, i.e., the three-dimensional surface shape, to be measured. The electromagnetic waves may include light rays such as laser light. The electromagnetic waves may be monochromatic laser light with a uniform phase. In this case, high-precision measurement of the surface shape of the first reflecting surface 31a is possible. The element or device emitting laser light may be a semiconductor laser element, a YAG laser device, or the like.

[0038] The surface shape of the first reflecting surface 31a may also be measured as follows: While irradiating a portion or the entire first reflecting surface 31a with electromagnetic waves, the positions of the first concave mirror 3 and the electromagnetic wave irradiation device are changed relative to each other, and multiple reflected images are captured by an image receiving device such as a camera. Based on the multiple reflected images, the entire surface shape of the first reflecting surface 31a is identified. For example, a light-section method using a two-dimensional laser displacement meter, or a so-called profiler, may also be used. The light-section method is a method for quickly and accurately capturing a continuous two-dimensional cross-sectional shape of an object using a strip-shaped laser beam. By processing the highly precise profiled two-dimensional cross-sectional shape using an image processing system, highly accurate three-dimensional cross-sectional shape data can be obtained. Alternatively, a pattern projection method may be used, in which multiple stripe-patterned light beams are repeatedly irradiated from multiple directions onto an object whose position changes due to intermittent rotation, etc., and the three-dimensional surface shape is captured based on the reflected light.

[0039] The surface shape of the second reflecting surface 32a of the second concave mirror 32 may also be measured in a similar manner using the method described above. Furthermore, if the optical system 3 includes an optical element such as a convex mirror other than the first concave mirror 31 and the second concave mirror 32, the surface shape of that optical element may also be measured in a similar manner using the method described above.

[0040] The first concave mirror 31 has a first curvature S31a and a second curvature S31b. The first curvature S31a and the second curvature S31b will be described below with reference to FIG.

[0041] FIG. 5 schematically illustrates a cross section of the first concave mirror 31 taken along a plane passing through the optical center OC1 of the first reflecting surface 31a and extending along the optical axis of the first reflecting surface 31a. The plane extending along the optical axis may be parallel to the YZ plane. As shown in FIG. 5 , the tangent plane of the first reflecting surface 31a at the optical center OC1 is defined as tangent plane T. Furthermore, points located at both ends (upper and lower ends) of the first reflecting surface 31a are defined as points E1 and E2, respectively. The intersection of a perpendicular line extending from point E1 to the tangent plane T with the tangent plane T is defined as point H1, and the intersection of a perpendicular line extending from point E2 to the tangent plane T with the tangent plane T is defined as point H2. Furthermore, the distance between the optical center OC1 and point H1 is defined as L1, the distance between the optical center OC1 and point H2 is defined as L2, the distance between point E1 and point H1 is defined as D1, and the distance between point E2 and point H2 is defined as D2. In this case, the first curvature S31a is defined by D1 / L1, and the second curvature S31b is defined by D2 / L2. The first curvature S31a is the curvature of a portion of the first concave mirror 31 located toward the upper side (a portion above the optical center OC1) and is also referred to as the upper curvature. The second curvature S31b is the curvature of a portion of the first concave mirror 31 located toward the lower side (a portion below the optical center OC1) and is also referred to as the lower curvature.

[0042] The second concave mirror 32 has a first curvature S32a and a second curvature S32b. The first curvature S32a and the second curvature S32b of the second concave mirror 32 are defined in the same manner as the first curvature S31a and the second curvature S31b of the first concave mirror 31. The first curvature S32a is the curvature of a portion of the second concave mirror 32 located toward the upper side, and is also referred to as the upper curvature. The second curvature S32b is the curvature of a portion of the second concave mirror 32 located toward the lower side, and is also referred to as the lower curvature.

[0043] The convex mirror 33 has a first curvature S33a and a second curvature S33b. The first curvature S33a and the second curvature S33b of the convex mirror 33 are defined in the same manner as the first curvature S31a and the second curvature S31b of the first concave mirror 31. The first curvature S33a is the curvature of a portion of the convex mirror 33 located toward the upper side, and is also referred to as the upper curvature. The second curvature S33b is the curvature of a portion of the convex mirror 33 located toward the lower side, and is also referred to as the lower curvature.

[0044] The deviation Δd1 may be normalized to a maximum value of 1 by the length of the first reflecting surface 31a along the tangent plane T in the cross-sectional view of FIG. 5 (i.e., the length equivalent to L1 + L2). The deviations Δd2 and Δd3 may also be normalized in the same manner as the deviation Δd1. In the following description, unless otherwise specified, the deviation Δd refers to the normalized deviation Δd. Furthermore, a deviation Δd with a unit (mm) refers to a non-normalized deviation Δd, and a deviation Δd without a unit (mm) refers to the normalized deviation Δd. Furthermore, when the deviation Δd is non-zero, it may be said that the deviation Δd exists or that the deviation Δd is present.

[0045] The existence of the deviation Δd1 makes it possible to change the first curvature (upper curvature) S31a and the second curvature (lower curvature) S31b of the first concave mirror 31 independently of one another. As a result, the direction, angle of incidence, and angle of reflection of light reflected by the first reflecting surface 31a of the first concave mirror 31 can be adjusted and set together, thereby achieving effects such as a reduction in the size of the optical system 3, an increase in the brightness of the floating image F, a reduction in distortion of the floating image F, a reduction in the field curvature of the floating image F, and a reduction in light leakage. The existence of the deviation Δd2 makes it possible to change the first curvature S32a and the second curvature S32b of the second concave mirror 32 independently of one another. As a result, the direction, angle of incidence, and angle of reflection of light reflected by the second reflecting surface 32a of the second concave mirror 32 can be adjusted and set together, thereby achieving the same effects as those described above. The existence of the deviation Δd3 makes it possible to change the first curvature S33a and the second curvature S33b of the convex mirror 33 independently of each other. As a result, the direction, incident angle, and reflection angle of the light reflected by the third reflecting surface 33a of the third concave mirror 33 can be adjusted and set together, achieving the same effect as above. Furthermore, the existence of at least two of the deviations Δd1, Δd2, and Δd3 enhances the above effect.

[0046] The floating image display device 1 is configured so that the deviation Δd 1 of the first concave mirror 31 is larger than the deviation Δd 2 of the second concave mirror 32 .

[0047] The floating image display device 1 has a deviation Δd1 in the first concave mirror 31. As shown in FIGS. 1 and 6 , the optical center OC1 of the first reflecting surface 31a may be located closer to the display unit 2 than the geometric center GC1 of the first reflecting surface 31a. In this case, the upper curvature S31a of the first concave mirror 31 (the curvature of the portion of the first concave mirror 31 closer to the convex mirror 33) can be increased. As a result, as shown in FIG. 6 , light L' reflected by the portion of the first concave mirror 31 closer to the convex mirror 33 can be incident on the third reflecting surface 33a of the convex mirror 33 at a deep angle of incidence (small angle of incidence). Light L' is reflected by the third reflecting surface 33a of the convex mirror 33 at a small angle of reflection. That is, light L' reflected by the third reflecting surface 33a of the convex mirror 33 is directed toward the lower end of the second concave mirror 32. As a result, the second concave mirror 32 that reflects the light L' reflected by the convex mirror 33 can be disposed close to the first concave mirror 31. Therefore, the optical system 3 can be made smaller in size in the height direction, and the floating image display device 1 can be made smaller in size in the height direction.

[0048] Furthermore, by increasing the upper curvature S31a of the first concave mirror 31, it is possible to reduce the risk that light L' reflected at a portion of the first concave mirror 31 closer to the convex mirror 33 will not enter the convex mirror 33 and will propagate into the space above the convex mirror 33. As a result, it is possible to improve the brightness uniformity of the floating image F. The brightness uniformity is expressed as {(minimum brightness of floating image F) / (maximum brightness of floating image F)} × 100 (%). Furthermore, it is possible to improve the light utilization rate of the floating image display device 1. As a result, it is possible to improve the brightness of the floating image F. Alternatively, it is possible to reduce the brightness of the image displayed on the display unit 2 while maintaining sufficient brightness of the floating image F, thereby reducing the power consumption of the floating image display device 1.

[0049] As shown in FIGS. 1 and 6 , the optical center OC3 of the third reflecting surface 33a may be located closer to the first concave mirror 31 than the geometric center GC3 of the third reflecting surface 33a. For example, the convex mirror 33 may have a deviation Δd3 in which the optical center OC3 is shifted from the geometric center GC3 toward the lower end of the convex mirror 33. In this case, the first curvature (upper curvature) S33a of the convex mirror 33 is greater than the second curvature (lower curvature) S33b. As a result, as shown in FIG. 6 , light L″ reflected from a portion of the first concave mirror 31 closer to the display unit 2 can be made to enter the portion of the third reflecting surface 33a of the convex mirror 33 with a shallower angle of incidence (larger angle of incidence), and the reflected light L″ can be directed toward the upper end of the second concave mirror 32. In order to reduce leakage of light L'' to the outside from the upper end of the second concave mirror 32, the convex mirror 33 can be moved closer to the first concave mirror 31 and the second concave mirror 32. As a result, the optical system 3 can be made smaller in the depth direction (Z direction), and the floating image display device 1 can be made smaller in the depth direction.

[0050] As shown in FIGS. 1 and 6 , the optical center OC2 of the second reflecting surface 32a may be located closer to the first concave mirror 31 than the geometric center GC2 of the second reflecting surface 32a. For example, the second concave mirror 32 may have a deviation Δd2 in which the optical center OC2 is closer to the lower end of the second concave mirror 32 from the geometric center GC2. In this case, the first curvature (upper curvature) S32a of the second concave mirror 32 is greater than the second curvature (lower curvature) S32b. As a result, as shown in FIG. 6 , light L″ reflected at the upper curvature S33a of the third reflecting surface 33a of the convex mirror 33 can be captured at the upper curvature S32a of the second concave mirror 32, reducing leakage to the outside. As a result, reductions in brightness and brightness uniformity of the floating image F can be reduced.

[0051] The deviation Δd2 is smaller than the deviation Δd1. That is, the deviation Δd1 is larger than the deviation Δd2. The second concave mirror 32 is an optical element that forms the floating image F, and if the deviation Δd2 is large, it is more likely to have an effect on increasing the distortion of the floating image F and reducing the brightness uniformity. Therefore, the deviation Δd2 is relatively smaller than the deviation Δd1. Furthermore, the second concave mirror 32 is an optical element that forms the floating image F, and in order to enlarge the floating image F, the size of the second concave mirror 32 may be larger than the size of the first concave mirror 31. In this case, if the deviation Δd2 is large, it is more likely to have an effect on increasing the distortion of the floating image F and reducing the brightness uniformity. Therefore, the deviation Δd2 is relatively smaller than the deviation Δd1.

[0052] The deviation Δd1 is a normalized value, and may be greater than 0 and less than 0.3, or greater than 0 and less than 0.25, in order to reduce the distortion of the floating image F, but is not limited to these ranges. Also, as shown in FIGS. 7 and 8, the deviation Δd1 may be in the range of 8 mm to 20 mm, or in the range of 10 mm to 20 mm, in order to reduce the distortion of the floating image F.

[0053] In order to reduce the increase in the distortion of the floating image, the deviation Δd2 is a normalized value and may be greater than 0 and less than 0.2, or greater than 0 and less than 0.15, but is not limited to these ranges. Furthermore, the deviation Δd2 may be greater than or equal to 0. A large deviation Δd2 is likely to increase the distortion of the floating image F and affect the reduction in brightness uniformity, so the deviation Δd2 may be 0. Furthermore, as shown in FIGS. 7 and 8, the deviation Δd2 may be 10 mm or less in order to reduce the distortion of the floating image F.

[0054] The size of the first concave mirror 31 and the second concave mirror 32 may be the maximum diameter of the reflecting surfaces 31 a, 32 a or the average diameter of the reflecting surfaces 31 a, 32 a. Furthermore, the size of the first concave mirror 31 and the second concave mirror 32 may be the maximum diameter of the reflecting surfaces 31 a, 32 a when viewed from the front, or the average diameter of the reflecting surfaces 31 a, 32 a when viewed from the front.

[0055] The first concave mirror 31 reflects the light L emitted from the display unit 2 in a direction different from the direction toward the display unit 2. Therefore, the optical axis direction of the first reflecting surface 31a is inclined with respect to the display surface 2a, which is likely to cause aberrations at the virtual image plane 4 of the floating image F. By increasing the deviation Δd1 of the first concave mirror 31, it is possible to reduce aberrations caused by the positional relationship between the display unit 2 and the first concave mirror 31. Of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 that constitute the optical system 3, the first concave mirror 31 has the longest optical path length from the virtual image plane 4. Therefore, even if the deviation Δd1 of the first concave mirror 31 is increased, there is little direct impact on distortion of the floating image F, field curvature, and the like.

[0056] The floating image display device 1 may be configured so that the deviation Δd 3 of the convex mirror 33 is larger than the deviation Δd 2 of the second concave mirror 32 .

[0057] Since the deviation Δd3 is larger than the deviation Δd2, the upper curvature S32a of the convex mirror 33 (the curvature of the upper portion of the convex mirror 33) can be increased, as shown in Fig. 6. This makes it easier for the convex mirror 33 to reflect the light L" incident on the upper portion of the convex mirror 33 in a direction that forms a relatively small angle with the height direction (Y-axis direction). As a result, the second concave mirror 32 that reflects the light L" reflected by the convex mirror 33 can be disposed close to the convex mirror 33. In other words, the convex mirror 33 can be disposed close to the second concave mirror 32. Therefore, the optical system 3 can be made smaller in the depth direction, and the floating-image display device 1 can be made smaller in the depth direction.

[0058] Of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 that constitute the optical system 3, the second concave mirror 32 has the shortest optical path length from the virtual image plane 4. Since the deviation Δd2 is smaller than the deviation Δd3, it is possible to reduce the bias of aberration at the virtual image plane 4, and to reduce the distortion of the floating image F.

[0059] The floating image display device 1 may be configured so that the deviation Δd3 of the convex mirror 33 is smaller than the deviation Δd1 of the first concave mirror 31. If the deviation Δd3 is larger than the deviation Δd1, it becomes difficult to correct the above-mentioned aberration that is likely to occur in the first concave mirror 31 in the optical system 3. By making the deviation Δd3 smaller than the deviation Δd1, it becomes possible to correct the aberration that is likely to occur in the first concave mirror 31 and reduce distortion of the floating image F.

[0060] As shown in FIGS. 7 and 8, the deviation Δd3 may be 10 mm or less in order to reduce the distortion of the floating image F.

[0061] The floating image display device 1 may be configured such that the curvature of the convex mirror 33 is smaller than either the curvature of the first concave mirror 31 or the curvature of the second concave mirror 32. The convex mirror 33 is more likely to magnify the light L than the first concave mirror 31 and the second concave mirror 32, and is more likely to increase the distortion of the floating image F. By making the curvature of the convex mirror 33 smaller than the curvatures of the first concave mirror 31 and the second concave mirror 32, the distortion of the floating image F can be reduced. Note that the curvature of the convex mirror 33 may be the average value of the first curvature S33a and the second curvature S33b, or may be the smaller of the first curvature S33a and the second curvature S33b. The same applies to the curvature of the first concave mirror 31 and the second concave mirror 32.

[0062] 7 is a graph showing the relationship between the deviation Δd and the maximum distortion of the floating image F in the X-axis direction (width direction). In FIG. 7, the deviation Δd is an unnormalized deviation Δd, the solid line is a straight line approximating the relationship between the maximum distortion of the floating image F in the width direction and the deviation Δd2, and the dashed line is a straight line approximating the relationship between the maximum distortion of the floating image F in the width direction and the deviation Δd3. Details of the maximum distortion of the floating image F will be described later (see FIG. 11).

[0063] 7, the four data (●) with different values ​​of deviation Δd1 correspond to Device No. 2, Device No. 3, Device No. 4, and Device No. 1, in order of increasing deviation Δd1. The configurations of Devices Nos. 1 to 4 will be described later. The four data (◆) with different values ​​of deviation Δd2 correspond to Device No. 3, Device No. 4, Device No. 1, and Device No. 2, in order of decreasing deviation Δd2. The four data (□) with different values ​​of deviation Δd3 correspond to Device No. 3, Device No. 4, Device No. 1, and Device No. 2, in order of decreasing deviation Δd3. The four data (▲) with different values ​​of the difference (Δd3 - Δd2) obtained by subtracting deviation Δd2 from deviation Δd3 correspond to Device No. 3, Device No. 4, Device No. 1, and Device No. 2, in order of decreasing difference. 1 and device No. 2. These correspondences also apply to FIGS.

[0064] As shown in Figure 7, by reducing the deviation Δd2 (◆) of the second concave mirror 32, the distortion of the floating image F in the width direction can be reduced. Furthermore, by reducing the deviation Δd3 (□) of the convex mirror 33, the distortion of the floating image F in the width direction can be reduced. Note that by reducing the difference (▲) obtained by subtracting the deviation Δd2 from the deviation Δd3, the distortion of the floating image F in the width direction can be reduced, but when the deviation Δd3 is smaller than the deviation Δd2, the distortion of the floating image F in the width direction increases. Since the first concave mirror 31 has the longest optical path length from the floating image F among the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 that make up the optical system 3, the deviation Δd1 (●) of the first concave mirror 31 has little effect on the distortion of the floating image F in the width direction.

[0065] 8 is a graph showing the relationship between the deviation Δd and the maximum distortion of the floating image F in the Y-axis direction (height direction). In Fig. 8, the deviation Δd is an unnormalized deviation Δd, the solid line is a straight line approximating the relationship between the maximum distortion of the floating image F in the height direction and the deviation Δd2, and the dashed line is a straight line approximating the relationship between the maximum distortion of the floating image F in the height direction and the deviation Δd3. Details of the maximum distortion of the floating image F will be described later (see Fig. 11).

[0066] As shown in Figure 8, by reducing the deviation Δd2 (◆) of the second concave mirror 32, the distortion of the floating image F in the height direction can be reduced. Furthermore, by reducing the deviation Δd3 (□) of the convex mirror 33, the distortion of the floating image F in the height direction can be reduced. Note that by reducing the difference (▲) obtained by subtracting the deviation Δd2 from the deviation Δd3, the distortion of the floating image F in the height direction can be reduced, but when the deviation Δd3 is smaller than the deviation Δd2, the distortion of the floating image F in the height direction becomes larger. Since the first concave mirror 31 has the longest optical path length from the floating image F among the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 that make up the optical system 3, the deviation Δd1 (●) of the first concave mirror 31 has little effect on the distortion of the floating image F in the height direction.

[0067] 9 is a graph showing the relationship between the deviation Δd and the field curvature of the floating image F. In FIG. 9, the deviation Δd is an unnormalized deviation Δd, the solid line is a straight line approximating the relationship between the field curvature of the floating image F and the deviation Δd2, and the dashed line is a straight line approximating the relationship between the field curvature of the floating image F and the deviation Δd3. As shown in FIG. 10, the field curvature refers to the phenomenon in which the floating image F curves in the Z-axis direction (depth direction). As the field curvature increases, it becomes difficult for the user 5 to focus their eyes on the entire floating image F, reducing the visibility of the floating image F. For example, when the user 5 focuses on the center of the floating image F and views the floating image F, the center of the floating image F appears clear, but the peripheral portion of the floating image F appears blurred. As shown in FIG. 10, the field curvature in monocular vision is determined by the maximum value FC of the distortion of the floating image F in the depth direction.

[0068] As shown in Figure 9, reducing the deviation Δd2 (◆) of the second concave mirror 32 can reduce the field curvature of the floating image F. Furthermore, reducing the deviation Δd3 (□) of the convex mirror 33 can reduce the field curvature of the floating image F. Note that reducing the difference (▲) obtained by subtracting the deviation Δd2 from the deviation Δd3 can reduce the field curvature of the floating image F, but if the deviation Δd3 is smaller than the deviation Δd2, the field curvature of the floating image F increases. Of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 that make up the optical system 3, the first concave mirror 31 has the longest optical path length from the floating image F, and therefore the deviation Δd1 (●) of the first concave mirror 31 has little effect on the field curvature of the floating image F.

[0069] Next, configuration examples of the floating image display device 1 (device Nos. 1 to 4) will be described. Below, for device Nos. 1 to 4, the size (length of the line segment connecting points H1 and H2 in FIG. 5) (unit: mm), geometric center (unit: mm), optical origin (unit: mm), and Δd1 (unit: mm) of the first concave mirror 31 are shown, the size, geometric center, optical origin, and Δd3 of the convex mirror 33 are shown, and the size, geometric center, optical origin, and Δd2 of the second concave mirror 32 are shown. The geometric center is half the size of the mirror (first concave mirror 31, second concave mirror 32, or convex mirror 33), the optical origin is the distance from the reference when the edge of the mirror (for example, the bottom edge) is used as the reference (L2 shown in FIG. 5), and Δd1 to Δd3 are the values ​​(absolute values) of (geometric center - optical origin). - Device No. 1 First concave mirror 31...size: 132.42, geometric center: 66.21, optical origin: 36.39, Δd1: 29.82 Convex mirror 33...size: 81.42, geometric center: 40.71, optical origin: 51.49, Δd3: 10.78 Second concave mirror 32...size: 254.00, geometric center: 127.00, optical origin: 113.69, Δd2: 13.3 Device No. 2 First concave mirror 31...size: 107.95, geometric center: 53.975, optical origin: 56.77, Δd1: 2.795 Convex mirror 33...size: 111.64, geometric center: 55.82, optical origin: 80.28, Δd3: 24.46 Second concave mirror 32...size: 247.90, geometric center: 123.95, optical origin: 139.1, Δd2: 15.15 Device No. 3 First concave mirror 31...size: 67.74, geometric center: 33.87, optical origin: 43.7, Δd1: 9.83 Convex mirror 33...size: 42.10, geometric center: 21.05, optical origin: 21.8, Δd3: 0.75 Second concave mirror 32...size: 161.70, geometric center: 80.85, optical origin: 80.15, Δd2: 0.70 Device No. 4 First concave mirror 31...size: 165.60, geometric center: 82.8, optical origin: 100.5, Δd1: 17.70 Convex mirror 33...size: 69.00, geometric center: 34.5, optical origin: 27.3, Δd3: 7.20 Second concave mirror 32...size: 251.10, geometric center: 125.55, optical origin: 127.6, Δd2: 2.05

[0070]

[0071] Table 1 shows the configurations of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 in devices No. 1 to 4. In Table 1, the optical origin of the first concave mirror 31 refers to the distance L2 between the lower point H2 of points H1 and H2 and the optical center OC1, when the size of the first concave mirror 31 is set to "1" (see FIG. 5). Therefore, when the optical origin is less than 0.5, the optical center OC1 can be said to be located below (on the side of point H2) the point of intersection of the perpendicular line from the geometric center GC1 to the tangent plane T with the tangent plane T. Furthermore, when the optical origin is greater than 0.5, the optical center OC1 can be said to be located above (on the side of point H1) the point of intersection of the perpendicular line from the geometric center GC1 to the tangent plane T with the tangent plane T. The same applies to the optical origins of the second concave mirror 32 and the convex mirror 33. In Table 1, deviations Δd1 to Δd3 refer to normalized deviations.

[0072]

[0073] Table 2 shows the curvatures of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 in devices Nos. 1 to 4.

[0074] 11 to 14 are simulation results showing the floating image F viewed by the user 5 of devices No. 1 to 4, respectively. In FIGS. 11 to 14, in order to facilitate visual understanding of the distortion of the floating image F, the floating image F is depicted as a floating image with a grid pattern, and coordinate axes indicating the direction and amount of distortion are shown, along with an ideal rectangular floating image IF without distortion. In FIGS. 11 to 14, the solid lines indicate the floating image F viewed by the user 5, and the dashed lines indicate the ideal rectangular floating image IF without distortion. The distortion of the floating image F can include distortion in the planar direction (XY plane direction) and distortion in the depth direction (Z axis direction), but FIGS. 11 to 14 only show distortion in the planar direction.

[0075] As shown in Figures 11 to 14, distortion of the floating image F is likely to occur in the outer periphery of the floating image F, and is particularly likely to be large at the four corners of the floating image F (lower right corner LR, upper right corner UR, lower left corner LL, and upper left corner UL). Tables 4 to 7 show the distortion from the floating image IF at the corners LR, UR, LL, and UL of the floating image F shown in Figures 8A to 8D, respectively. As shown in Tables 3 to 6, the floating image display device 1 can reduce the distortion at the corners LR, UR, LL, and UL to within 5%. Note that when it is said that the distortion is "within 5%," it means that the absolute value of the distortion is within 5%.

[0076] The + (plus) direction in the X-axis direction is the right direction in FIGS. 11 to 14 , and the − (minus) direction in the X-axis direction is the left direction in FIGS. 11 to 14 . The + (plus) direction in the Y-axis direction is the upward direction in FIGS. 11 to 14 , and the − (minus) direction in the Y-axis direction is the downward direction in FIGS. 11 to 14 . The distortion of the floating image F is defined as a positive value when the floating image F is distorted outward from the ideal floating image IF in both the X-axis direction and the Y-axis direction, and a negative value when the floating image F is distorted inward from the ideal floating image IF. For example, at the lower right corner LR, the outward direction in the X-axis direction (rightward: expanding direction) is defined as the + (plus) direction, the inward direction in the X-axis direction (leftward: shrinking direction) is defined as the − (minus) direction, the outward direction in the Y-axis direction (downward: expanding direction) is defined as the + (plus) direction, and the inward direction in the Y-axis direction (upward: shrinking direction) is defined as the − (minus) direction. The same applies to the upper right corner UR, the lower left corner LL, and the upper left corner UL. The same also applies to the following tables showing the distortion of the floating image F.

[0077] The distortion at the corners LR, UR, LL, and UL is calculated as follows. The distortion at the corners LR, UR, LL, and UL in the X-axis direction is defined by the offset length in the X-axis direction relative to the length LX of the top edge of the rectangular floating image IF. Because the rectangular floating image IF has the same length of top and bottom edges, the distortion in the X-axis direction is defined using the length LX of the top edge as a reference. For example, the distortion at the corner UR in the X-axis direction is defined by the offset length ΔXUR in the X-axis direction from the upper right corner CUR of the floating image IF relative to the length LX of the top edge. In other words, the distortion at the corner UR in the X-axis direction is defined by (ΔXUR / LX)×100(%). Because the corner UR is distorted inward of the aerial image IR in the X-axis direction, the value is negative (-). The distortion at the corners LR, LL, and UL in the X-axis direction is defined similarly. When the floating image IF has a shape other than a rectangle, the reference length in the X-axis direction may be the average length or the maximum length.

[0078] The distortion of the corners LR, UR, LL, and UL in the Y-axis direction is defined by the displacement length in the Y-axis direction relative to the length LY of the right side of the rectangular floating image IF. Since the length of the left side and the length LY of the right side of the rectangular floating image IF are the same, the distortion in the Y-axis direction is defined using the length LY of the right side as a reference. For example, the distortion of the corner UR in the Y-axis direction is defined by the displacement length ΔYUR in the Y-axis direction from the upper right corner CUR of the floating image IF relative to the length LY of the right side. In other words, the distortion of the corner UR in the Y-axis direction is defined by (ΔYUR / LY) × 100 (%). Because the corner UR is distorted inward of the floating image IF in the Y-axis direction, the value is negative (-). The distortion of the corners LR, LL, and UL in the Y-axis direction is defined similarly. When the floating image IF has a shape other than a rectangle, the reference length in the Y-axis direction may be the average length or the maximum length.

[0079]

[0080]

[0081]

[0082]

[0083] Tables 3 to 6 show the distortion of the floating image F at the corners LR, UR, LL, and UL in device Nos. 1 to 4. As shown in Tables 3 to 6, according to the floating image display device 1 of this embodiment, at the corners LR, UR, LL, and UL where distortion of the floating image F is likely to occur, distortion in both the X-axis direction and the Y-axis direction can be reduced to within 5%.

[0084]

[0085] Table 7 shows the maximum distortion and field curvature of the floating image F in devices No. 1 to 4. The maximum distortion (X) indicates the maximum absolute value of the distortion of the corners LR, UR, LL, and UL in the X-axis direction, and the maximum distortion (Y) indicates the maximum absolute value of the distortion of the corners LR, UR, LL, and UL in the Y-axis direction. As shown in Table 7, according to the floating image display device 1 of this embodiment, the distortion in both the X-axis and Y-axis directions at the corners LR, UR, LL, and UL can be reduced to within 5%, while the field curvature can be reduced to within 7 mm.

[0086] A floating image display device according to another embodiment of the present disclosure will now be described. Figures 15 to 18 are diagrams or graphs illustrating a floating image display device according to another embodiment of the present disclosure. The floating image display device of this embodiment differs from the floating image display device of the above-described embodiment in the configuration of the optical system, but otherwise has the same configuration, so the same reference numerals as in the floating image display device of the above-described embodiment will be used for the similar configuration, and detailed description will be omitted.

[0087] 15, the floating image display device 1A of this embodiment includes a display unit 2 and an optical system 6. The optical system 6 has a first concave mirror 61 and a second concave mirror 62.

[0088] The first concave mirror 61 has a first reflecting surface 61 a that is a concave surface. The first concave mirror 61 reflects the light L emitted from the display unit 2 in a direction different from the direction toward the display unit 2.

[0089] The second concave mirror 62 has a concave second reflecting surface 62a. The second concave mirror 62 reflects the light L reflected by the first concave mirror 31 in a direction different from the direction toward the first concave mirror 61, forming a real floating image F. Hereinafter, when there is no need to distinguish between the first reflecting surface 61a and the second reflecting surface 62a, they may be simply referred to as "reflecting surfaces 61a, 62a."

[0090] The first concave mirror 61 may be a free-form concave mirror whose first reflecting surface 61 a is defined by a free-form surface. The second concave mirror 62 may be a free-form concave mirror whose second reflecting surface 62 a is defined by a free-form surface. The free-form surfaces that define the reflecting surfaces 61 a and 62 a may be defined by the above-mentioned formulas (1) and (2).

[0091] The first concave mirror 61 and the second concave mirror 62 may be aspherical mirrors. In other words, the reflecting surfaces 61 a and 62 a may be defined by a quadric surface such as a paraboloid, an ellipsoid, or a hyperboloid.

[0092] The first concave mirror 61 has an optical center OC1, and the second concave mirror 62 has an optical center OC2. The optical center OC1 of the first concave mirror 61 and the optical center OC2 of the second concave mirror 62 are defined in the same manner as the optical center OC1 of the first concave mirror 31 and the optical center OC2 of the second concave mirror 32, respectively. Hereinafter, when the optical centers OC1 and OC2 are not to be distinguished from each other, they may be simply referred to as "optical centers OC."

[0093] The first concave mirror 61 has a geometric center GC1, and the second concave mirror 62 has a geometric center GC2. The geometric center GC1 of the first concave mirror 61 and the geometric center GC2 of the second concave mirror 62 are defined in the same manner as the geometric center GC1 of the first concave mirror 31 and the geometric center GC2 of the second concave mirror 32, respectively. Hereinafter, when the geometric centers GC1 and GC2 are not distinguished from each other, they may be simply referred to as the "geometric center GC." Hereinafter, viewing the first concave mirror 61 (first reflecting surface 61a) from the normal direction of the tangent plane T may be referred to as the "front view." The same applies to the front view of the second concave mirror 62.

[0094] The geometric center GC1 and optical center OC1 of the first concave mirror 61 may or may not coincide with each other. The same applies to the second concave mirror 62. In this specification, the amount of decentering of the optical center OC1 from the geometric center GC1 of the first concave mirror 61 is referred to as deviation Δd1, and the amount of decentering of the optical center OC2 from the geometric center GC2 of the second concave mirror 62 is referred to as deviation Δd2. Hereinafter, when there is no need to distinguish between the deviation Δd1 and the deviation Δd2, they may be simply referred to as "deviation Δd."

[0095] The deviation Δd may be the shortest distance along the reflecting surfaces 61 a, 62 a between the geometric center GC and the optical center OC. The deviation Δd may also be the straight-line distance between the geometric center GC and the optical center OC. When the curvature of the region including the geometric center GC and the optical center OC on the reflecting surfaces 61 a, 62 a is relatively small, the straight-line distance between the geometric center GC and the optical center OC approximately coincides with the shortest distance along the reflecting surfaces 61 a, 62 a between the geometric center GC and the optical center OC.

[0096] The first concave mirror 61 has a first curvature S61a and a second curvature S61b. The first curvature S61a is the curvature of a portion of the first concave mirror 61 far from the display unit 2 (the portion on the opposite side of the display unit 2 from the optical center OC1). The second curvature S61b is the curvature of a portion of the first concave mirror 61 closer to the display unit 2 (the portion on the display unit 2 side from the optical center OC1). The first curvature S61a and second curvature S61b of the first concave mirror 61 are defined in the same way as the first curvature S31a and second curvature S31b of the first concave mirror 31.

[0097] The second concave mirror 62 has a first curvature S62a and a second curvature S62b. The first curvature S62a is the curvature of an upper portion of the second concave mirror 62 (a portion above the optical center OC2). The second curvature S62b is the curvature of a lower portion of the second concave mirror 62 (a portion below the optical center OC2). The first curvature S62a and the second curvature S62b of the second concave mirror 62 are defined in the same manner as the first curvature S32a and the second curvature S32b of the second concave mirror 32. The floating image display device 1A may be configured such that the curvature of the second concave mirror 62 is smaller than the curvature of the first concave mirror 61. The second concave mirror 62 is an optical element that forms a floating image F. The curvature of the second concave mirror 62 is smaller than the curvature of the first concave mirror 61, thereby reducing distortion of the floating image F. The curvature of the second concave mirror 62 may be the average value of the first curvature S62a and the second curvature S62b, or may be the smaller of the first curvature S62a and the second curvature S62b. The same applies to the curvature of the first concave mirror 61.

[0098] The deviation Δd1 and the deviation Δd2 may be normalized so that their maximum values ​​are 1. The normalization of the deviation Δd1 and the deviation Δd2 is similar to the normalization described above. In the following description, unless otherwise specified, the deviation Δd refers to the normalized deviation Δd.

[0099] By making the deviation Δd1 different from "0", it is possible to change the first curvature S61a and the second curvature S61b of the first concave mirror 61 independently of each other. By making the deviation Δd2 different from "0", it is possible to change the first curvature S62a and the second curvature S62b of the second concave mirror 62 independently of each other.

[0100] The floating image display device 1A is configured so that the deviation Δd1 of the first concave mirror 61 is larger than the deviation Δd2 of the second concave mirror 62.

[0101] In the floating image display device 1A, if the light L reflected by the first reflecting surface 61a enters the display unit 2 (causing vignetting of the light L), there is a risk that a portion of the floating image F will be missing or that stray light will be generated, which will degrade the display quality of the floating image display device 1A. The vignetting of the light L can be reduced by increasing the angle θ (see FIG. 16 ) between the display surface 2a and the tangent plane T of the first reflecting surface 61a, but in that case, the difference in the optical path length between the display surface 2a and the first reflecting surface 61a for each light ray (light ray included in the light L) will increase, which will likely cause aberrations in the virtual imaging plane 4 of the floating image F.

[0102] In the floating image display device 1A, the deviation Δd1 in the first concave mirror 61 allows the first curvature S61a of the first concave mirror 61 (the curvature of the portion of the first concave mirror 61 far from the display unit 2) to be increased. As a result, vignetting of the light L can be reduced without increasing the angle θ between the display surface 2a and the tangent plane T of the first reflecting surface 61a. Therefore, distortion of the floating image F can be reduced and the brightness uniformity of the floating image F can be improved. Furthermore, since the display unit 2 can be disposed close to the first concave mirror 61, the floating image display device 1A can be made smaller.

[0103] In the floating image display device 1A, the deviation Δd2 is smaller than the deviation Δd1. That is, the deviation Δd1 is larger than the deviation Δd2. The second concave mirror 62 is an optical element that forms the floating image F, and if the deviation Δd2 is large, it is more likely to have an effect on increasing the distortion of the floating image F and reducing the brightness uniformity. Therefore, the deviation Δd2 is relatively smaller than the deviation Δd1. Furthermore, the second concave mirror 62 is an optical element that forms the floating image F, and in order to enlarge the floating image F, the size of the second concave mirror 62 may be larger than the size of the first concave mirror 61. In that case, if the deviation Δd2 is large, it is more likely to have an effect on increasing the distortion of the floating image F and reducing the brightness uniformity. Therefore, the deviation Δd2 is relatively smaller than the deviation Δd1.

[0104] The deviation Δd1 is a normalized value that may be greater than 0 and less than 0.3, or greater than 0 and less than 0.25, but is not limited to these ranges, in order to reduce the distortion of the floating image F from becoming large. The deviation Δd2 is a normalized value that may be greater than 0 and less than 0.2, or greater than 0 and less than 0.15, but is not limited to these ranges, in order to reduce the distortion of the floating image F from becoming large.

[0105] Furthermore, the deviation Δd2 may be equal to or greater than 0. If the deviation Δd2 is large, it is likely to have an effect on increasing the distortion of the floating image F and decreasing the brightness uniformity, so the deviation Δd2=0 may be acceptable.

[0106] The size of the first concave mirror 61 and the second concave mirror 62 may be the maximum diameter of the reflecting surfaces 61 a, 62 a or the average diameter of the reflecting surfaces 61 a, 62 a. Furthermore, the size of the first concave mirror 61 and the second concave mirror 62 may be the maximum diameter of the reflecting surfaces 61 a, 62 a when viewed from the front, or the average diameter of the reflecting surfaces 61 a, 62 a when viewed from the front.

[0107] 17 is a graph showing the relationship between the deviation Δd and the maximum distortion of the floating image F in the Y-axis direction (height direction). In FIG. 17, the deviation Δd is a deviation Δd that shows an actual value that has not been normalized, the solid line is a straight line that approximates the relationship between the maximum distortion of the floating image F in the height direction and the deviation Δd2, and the dashed line is a straight line that approximates the relationship between the maximum distortion of the floating image F in the height direction and the difference obtained by subtracting the deviation Δd2 from the deviation Δd1 (i.e., Δd1-Δd2). The maximum distortion of the floating image F is as described above.

[0108] 17, the five data (●) with different values ​​of deviation Δd1 correspond to device No. 9, device No. 5, device No. 8, device No. 6, and device No. 7, in order from smallest to largest deviation Δd1. The configurations of device Nos. 5 to 9 will be described later. The five data (◆) with different values ​​of deviation Δd2 correspond to device No. 8, device No. 9, device No. 5, device No. 6, and device No. 7, in order from smallest to largest deviation Δd2. The four data (△) with different values ​​of the difference (Δd1 - Δd2) obtained by subtracting deviation Δd2 from deviation Δd1 correspond to device No. 7, device No. 6, device No. 5, device No. 9, and device No. 8, in order from smallest to largest difference. These correspondences are also true in FIG. 18.

[0109] 17, by reducing the deviation Δd2 (◆), the distortion of the floating image F in the height direction can be reduced. Furthermore, by reducing the difference (△) obtained by subtracting the deviation Δd2 from the deviation Δd1, the distortion of the floating image F in the height direction can be reduced, but when the deviation Δd1 is smaller than the deviation Δd2, the distortion of the floating image F in the height direction becomes larger. Since the first concave mirror 61 has the longest optical path length from the floating image F among the first concave mirror 61 and the second concave mirror 62 that constitute the optical system 6, the deviation Δd1 (●) of the first concave mirror 61 has little effect on the distortion of the floating image F in the width direction.

[0110] Fig. 18 is a graph showing the relationship between the deviation Δd and the field curvature of a floating image F. In Fig. 18, the deviation Δd is a deviation Δd that indicates an actual value that has not been normalized, the solid line is a straight line that approximates the relationship between the field curvature of the floating image F and Δd2, and the broken line is a straight line that approximates the relationship between the field curvature of the floating image F and the difference (i.e., Δd1-Δd2) obtained by subtracting the deviation Δd2 from the deviation Δd1. The field curvature is as described above.

[0111] 18, by reducing the deviation Δd2 (◆), the field curvature of the floating image F can be reduced. Furthermore, by increasing the difference (△) obtained by subtracting the deviation Δd2 from the deviation Δd1 within a positive range, the field curvature of the floating image F can be reduced. Since the first concave mirror 61 has the longest optical path length from the floating image F among the first concave mirror 61 and the second concave mirror 62 that constitute the optical system 6, the deviation Δd1 (●) of the first concave mirror 61 has little effect on the field curvature of the floating image F.

[0112]

[0113] Next, configuration examples of the floating image display device 1A (device Nos. 5 to 9) will be described. The following shows the size (corresponding to the length of the line segment connecting points H1 and H2 in FIG. 5) (unit: mm), geometric center (unit: mm), optical origin (unit: mm), and Δd1 (unit: mm) of the first concave mirror 61 of device Nos. 5 to 9, and the size, geometric center, optical origin, and Δd2 of the second concave mirror 62. The geometric center is half the size of the mirror (first concave mirror 61 or second concave mirror 62), the optical origin is the distance from the reference when the edge of the mirror (for example, the left edge in the case of the first concave mirror 61, and the bottom edge in the case of the second concave mirror 62) is used as the reference, and Δd1 to Δd3 are the values ​​(absolute values) of (geometric center - optical origin). - Device No. 5 First concave mirror 61...size: 193.30, geometric center: 96.65, optical origin: 80.00, Δd1: 16.65 Second concave mirror 62...size: 359.10, geometric center: 179.55, optical origin: 165.70, Δd2: 13.85 Device No. 6 First concave mirror 61...size: 177.70, geometric center: 88.85, optical origin: 50.10, Δd1: 38.85 Second concave mirror 62...size: 352.80, geometric center: 176.40, optical origin: 216.30, Δd2: 39.90 Device No. 7 First concave mirror 61...size: 191.90, geometric center: 95.95, optical origin: 54.40, Δd1: 41.55 Second concave mirror 62...size: 363.90, geometric center: 181.95, optical origin: 240.50, Δd2: 58.55 Device No. 8 First concave mirror 61...size: 195.20, geometric center: 97.60, optical origin: 64.30, Δd1: 33.30 Second concave mirror 62...size: 364.50, geometric center: 182.25, optical origin: 182.70, Δd2: 0.45 Device No. 9 First concave mirror 61...size: 104.60, geometric center: 52.3, optical origin: 65.80, Δd1: 13.50 Second concave mirror 62...size: 192.70, geometric center: 96.35, optical origin: 93.00, Δd2: 3.35

[0114] Table 8 shows the configurations of the first concave mirror 61 and the second concave mirror 62 in Devices No. 5 to 9. The optical origin of the first concave mirror 61 refers to the distance between point H2 and the optical center OC1 when the size of the first concave mirror 61 is defined as "1" (see FIG. 5). Therefore, when the optical origin of the first concave mirror 61 is less than 0.5, the optical center OC1 is located closer to the display unit 2 than the geometric center GC1. When the optical origin of the first concave mirror 61 is greater than 0.5, the optical center OC1 is located farther from the display unit 2 than the geometric center GC1. When the optical origin of the second concave mirror 62 is less than 0.5, the optical center OC2 is located below the geometric center GC2. When the optical origin of the second concave mirror 62 is greater than 0.5, the optical center OC1 is located above the geometric center GC2.

[0115] Devices No. 5 to 9 have the effects of miniaturizing the optical system 6, improving the brightness uniformity of the floating image F, reducing distortion of the floating image F, etc.

[0116] Other configuration examples of the floating image display devices 1 and 1A will be described below.

[0117] The second concave mirrors 32, 62 may be larger than the first concave mirrors 31, 61. In this case, it becomes easier for the user 5 to visually recognize the floating image F that is enlarged relative to the image displayed on the display unit 2. Furthermore, when the second concave mirrors 32, 62 are relatively large, the second reflecting surface 32a is made large enough to cover the spread of the light rays contained in the light L, which makes it easier to reduce the decrease in brightness of the floating image F.

[0118] The size of the first concave mirror 31, 61 may be defined by the maximum diameter of the first reflecting surface 31 a, 61 a passing through the geometric center GC1 in a front view (see FIGS. 2 to 4). The size of the second concave mirror 32, 62 may be defined by the maximum diameter of the second reflecting surface 32 a, 62 a passing through the geometric center GC2 in a front view.

[0119] When the first reflecting surface 31a, 61a is circular in front view, the size of the first concave mirror 31, 61 may be the diameter of the circle (see FIG. 2). When the first reflecting surface 31a, 61a is elliptical in front view, the size of the first concave mirror 31, 61 may be the length of the major axis of the ellipse. When the first reflecting surface 31a, 61a is rectangular in front view, the size of the first concave mirror 31, 61 may be the length of the diagonal of the rectangle (see FIG. 3). The same applies to the size of the second concave mirror 32, 62.

[0120] The size of the first concave mirrors 31, 61 may be, for example, approximately 150 mm to 200 mm. The size of the second concave mirrors 32, 62 may be, for example, approximately 200 mm to 350 mm. The size of the convex mirror 33 may be, for example, approximately 100 mm to 150 mm. The size of the convex mirror 33 may be specified in the same manner as the sizes of the first concave mirrors 31, 61 and the second concave mirrors 32, 62.

[0121] The size of the first concave mirror 31, 61 may be defined by the area of ​​the first reflecting surface 31 a, 61 a or the area of ​​the first reflecting surface 31 a, 61 a in a front view. The size of the second concave mirror 32, 62 may be defined by the area of ​​the second reflecting surface 32 a, 62 a or the area of ​​the second reflecting surface 32 a, 62 a in a front view. The size of the convex mirror 33 may be defined by the area of ​​the third reflecting surface 33 a or the area of ​​the third reflecting surface 33 a in a front view.

[0122] The floating image display devices 1 and 1A each include a controller, which is connected to each component of the floating image display devices 1 and 1A and controls each component.

[0123] The controller may have, for example, a function to turn the display unit 2 on and off, a function to send an image signal to the display unit 2, and a function to adjust the brightness, chromaticity, frame frequency, etc. of an image displayed on the display unit 2. If the display unit 2 has a heat dissipation member or a cooling member, the controller may have a function to adjust the temperature of the heat dissipation member or the cooling member.

[0124] The controller may be configured to include one or more processors. The processor may include a general-purpose processor configured to load a specific program and 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 a field-programmable gate array (FPGA). The controller may be a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors are configured to work together.

[0125] As shown in FIG. 19 , the floating image display device 1, 1A may be mounted on a moving body (i.e., a vehicle) 10 such as a vehicle, ship, or aircraft. Examples of vehicles include automobiles, industrial vehicles, railroad vehicles, residential vehicles, and fixed-wing aircraft that travel on runways. Examples of automobiles include passenger cars, trucks, buses, motorcycles, and trolleybuses. Examples of industrial vehicles include agricultural and construction vehicles. Examples of industrial vehicles include forklifts and golf carts. Examples of agricultural industrial vehicles include tractors, cultivators, transplanters, binders, combines, and lawn mowers. Examples of construction industrial vehicles include bulldozers, scrapers, excavators, crane trucks, dump trucks, and road rollers. Vehicles may also include human-powered vehicles. Examples of ships include marine jets, boats, and tankers. Examples of aircraft include fixed-wing aircraft and rotary-wing aircraft.

[0126] The moving body 10 equipped with the floating image display device 1, 1A can allow the user 5 (for example, the driver of the moving body 10) to visually recognize a floating image F with little distortion. The floating image F may include information about the state of the moving body 10 (for example, the speed, acceleration, posture, etc. of the moving body 10), the surrounding situation of the moving body 10, etc.

[0127] The floating image display device 1, 1A may be configured to include a camera that captures an image of the face of the user 5. The controller may detect the eye position of the user 5 based on the image data output from the camera. The controller may deform the image displayed on the display unit 2 based on the detected eye position. In this case, even if the eye position of the user 5 moves, it is possible to reduce distortion of the floating image F visually recognized by the user 5. When the floating image display device 1, 1A is mounted on a mobile object 10, the camera may be located in various places such as a rearview mirror, an instrument panel, a steering wheel, or a dashboard.

[0128] The floating image display device 1 may include a drive unit that moves at least one of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33. The floating image display device 1A may include a drive unit that moves at least one of the first concave mirror 61 and the second concave mirror 62. The controller may control the drive unit to move at least one of the first concave mirror 31, the second concave mirror 32, and the convex mirror 33 of the floating image display device 1 based on the detected eye position of the user 5, or may control the drive unit to move at least one of the first concave mirror 61 and the second concave mirror 62 of the floating image display device 1A. In this case, even when the eye position of the user 5 moves, it is possible to reduce distortion of the floating image F viewed by the user 5. The drive unit may include, for example, a motor, a piezoelectric element, etc.

[0129] A configuration in which a portion of the edge of the first concave mirror 31 and a portion of the edge of the second concave mirror 32 are in contact with each other is also possible. For example, in the configurations of Figures 1 and 6, a configuration in which the upper edge of the first concave mirror 31 and the lower edge of the second concave mirror 32 are in contact with each other is also possible. In this case, the floating image display device 1 is further miniaturized in the height direction. Furthermore, since there is no gap between the upper edge of the first concave mirror 31 and the lower edge of the second concave mirror 32, leakage of image light L from the gap can be reduced. As a result, a decrease in the brightness of the floating image F can be reduced.

[0130] The first concave mirror 31 may include a resin body and a reflective layer on a surface of the body corresponding to the first reflective surface 31a, and the second concave mirror 32 may include a resin body and a reflective layer on a surface of the body corresponding to the second reflective surface 32a. In this case, the first concave mirror 31 and the second concave mirror 32 can be made lighter than when the first concave mirror 31 and the second concave mirror 32 are made of a metal such as aluminum, thereby reducing the weight of the floating image display device 1. The reflective layer may be an aluminum layer, a silver layer, or the like. The aluminum layer has a high light reflectance of approximately 80% to 95%, although the light reflectance varies depending on the formation method, such as electropolishing, alloying, etc. The silver layer has a high light reflectance of approximately 90% to 93%.

[0131] The floating image display device 1, 1A may be mounted on a head-up display (HUD). The HUD may be mounted on the moving body 10. Part of the configuration of the HUD may be shared with other components of the moving body 10. For example, the windshield 11 of the moving body 10 may also be used as the second concave mirror 32, 62.

[0132] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments. Various modifications, improvements, etc. are possible within the scope of the gist of the present disclosure. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the invention of the present disclosure. For example, functions contained in each component, etc., can be rearranged so as not to cause logical contradictions, and multiple components, etc., can be combined into one or separated. In other words, it should be noted that a person skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. It should also be noted that these modifications, alterations, or alterations are included within the scope of the present disclosure.

[0133] According to the present disclosure, it is possible to reduce the size of a floating image display device and improve the display quality of the floating image display device.

[0134] The present disclosure can be implemented with the following configurations (1) to (15).

[0135] (1) A floating image display device comprising: a display unit; and an optical system having at least a first concave mirror that reflects light emitted from the display unit in a direction different from the direction toward the display unit; and a second concave mirror that reflects the light reflected by the first concave mirror in a direction different from the direction toward the first concave mirror and forms a floating image of a real image, wherein Δd1 is the deviation between the geometric center and the optical center of a first reflecting surface of the first concave mirror, and Δd2 is the deviation between the geometric center and the optical center of a second reflecting surface of the second concave mirror, where Δd1 > Δd2.

[0136] (2) The floating image display device according to the above configuration (1), wherein the optical center of the first reflecting surface is located at a position closer to the display unit with respect to the geometric center of the first reflecting surface.

[0137] (3) The floating image display device according to the above configuration (1) or (2), wherein the optical center of the second reflecting surface is located at a position closer to the first concave mirror with respect to the geometric center of the second reflecting surface.

[0138] (4) The optical center of the first reflecting surface is the vertex of the curvature of the first reflecting surface, and the optical center of the second reflecting surface is the vertex of the curvature of the second reflecting surface. A floating image display device according to any one of the above configurations (1) to (3).

[0139] (5) The floating image display device according to any one of the above configurations (1) to (4), wherein the first concave mirror and the second concave mirror are free-form concave mirrors, the optical center of the first reflecting surface is the origin of the free-form surface, and the optical center of the second reflecting surface is the origin of the free-form surface.

[0140] (6) The floating image display device according to any one of the above configurations (1) to (5), wherein the size of the second concave mirror is larger than the size of the first concave mirror, and the curvature of the second concave mirror is smaller than the curvature of the first concave mirror.

[0141] (7) The floating image display device according to any one of the above configurations (1) to (6), wherein the optical system has a convex mirror in the optical path between the first concave mirror and the second concave mirror, which reflects the light reflected by the first concave mirror in a direction toward the second concave mirror, and when the deviation between the geometric center and the optical center of the third reflecting surface of the convex mirror is Δd3, Δd3>Δd2.

[0142] (8) The floating image display device according to the above configuration (7), wherein the optical center of the third reflecting surface is located at a position closer to the first concave mirror with respect to the geometric center of the third reflecting surface.

[0143] (9) The floating image display device according to the above configuration (7) or (8), wherein the optical center of the third reflecting surface is the apex of the curvature of the third reflecting surface.

[0144] (10) The floating image display device according to any one of the above configurations (7) to (9), wherein the convex mirror is a free-form convex mirror, and the optical center of the third reflecting surface is the origin of the free-form surface.

[0145] (11) The floating image display device according to any one of the above configurations (7) to (10), wherein the curvature of the convex mirror is smaller than the curvature of both the first concave mirror and the second concave mirror.

[0146] (12) The floating image display device according to any one of the above configurations (7) to (11), wherein Δd1>Δd3>Δd2.

[0147] (13) The floating image display device according to any one of the above configurations (1) to (12), wherein a part of an edge of the first concave mirror and a part of an edge of the second concave mirror are in contact with each other.

[0148] (14) The floating image display device according to any one of the above configurations (1) to (13), wherein the first concave mirror comprises a body made of resin and a reflective layer on a surface of the body corresponding to the first reflective surface, and the second concave mirror comprises a body made of resin and a reflective layer on a surface of the body corresponding to the second reflective surface.

[0149] (15) A moving object comprising the floating image display device according to any one of the above configurations (1) to (14). Industrial application fields

[0150] 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 and communication with floating images, a medical interview device in which a doctor interviews a patient through floating images, a navigation device and driving control device for vehicles such as automobiles, an order placement and reception device and cash register device for stores, an operation panel for buildings, elevators, etc., a learning device for teaching or taking classes with floating images, an office machine for business communication and instructions with floating images, an amusement machine for playing games with floating images, a projection device for projecting images onto the ground or wall surface at an amusement park or game center, a simulator device for conducting simulation experiments with floating images at universities, medical institutions, etc., a large display that displays prices at markets or stock exchanges, an image viewing device for viewing images of floating images, etc.

[0151] REFERENCE SIGNS LIST 1, 1A Floating image display device 2 Display unit 2a Display surface 3 Optical system 31 First concave mirror 31a First reflecting surface 32 Second concave mirror 32a Second reflecting surface 33 Convex mirror 33a Third reflecting surface 4 Virtual image plane 5 User 6 Optical system 61 First concave mirror 61a First reflecting surface 62 Second concave mirror 62a Second reflecting surface 10 Mobile object 11 Windshield F Floating image

Claims

1. A floating image display device comprising: a display unit; an optical system having at least a first concave mirror that faces the display unit at an angle; and a second concave mirror that faces the first concave mirror at an angle and forms a floating image of a real image; wherein, when the deviation between the geometric center and the optical center of a first reflecting surface of the first concave mirror is Δd1 and the deviation between the geometric center and the optical center of a second reflecting surface of the second concave mirror is Δd2, Δd1 > Δd2.

2. The floating image display device according to claim 1, wherein the optical center of the first reflecting surface is located at a position closer to the display unit with respect to the geometric center of the first reflecting surface.

3. A floating image display device according to claim 1 or 2, wherein the optical center of the second reflecting surface is located at a position closer to the first concave mirror with respect to the geometric center of the second reflecting surface.

4. A floating image display device according to any one of claims 1 to 3, wherein the optical center of the first reflecting surface is the apex of the curvature of the first reflecting surface, and the optical center of the second reflecting surface is the apex of the curvature of the second reflecting surface.

5. A floating image display device according to any one of claims 1 to 4, wherein the first concave mirror and the second concave mirror are free-form concave mirrors, the optical center of the first reflecting surface is the origin of the free-form surface, and the optical center of the second reflecting surface is the origin of the free-form surface.

6. A floating image display device according to any one of claims 1 to 5, wherein the size of the second concave mirror is larger than the size of the first concave mirror, and the curvature of the second concave mirror is smaller than the curvature of the first concave mirror.

7. A floating image display device according to any one of claims 1 to 6, wherein the optical system has a convex mirror in the optical path between the first concave mirror and the second concave mirror, which reflects the light reflected by the first concave mirror in a direction toward the second concave mirror, and when the deviation between the geometric center and the optical center of the third reflecting surface of the convex mirror is Δd3, Δd3 > Δd2.

8. The floating image display device according to claim 7, wherein the optical center of the third reflecting surface is located at a position closer to the first concave mirror with respect to the geometric center of the third reflecting surface.

9. The floating image display device according to claim 7 or 8, wherein the optical center of the third reflecting surface is the apex of the curvature of the third reflecting surface.

10. A floating image display device according to any one of claims 7 to 9, wherein the convex mirror is a free-form convex mirror, and the optical center of the third reflecting surface is the origin of the free-form surface.

11. The floating image display device according to any one of claims 7 to 10, wherein the curvature of the convex mirror is smaller than the curvature of both the first concave mirror and the second concave mirror.

12. The floating image display device according to any one of claims 7 to 10, wherein Δd1>Δd3>Δd2.

13. The floating image display device according to any one of claims 1 to 12, wherein a part of the edge of the first concave mirror and a part of the edge of the second concave mirror are in contact with each other.

14. A floating image display device as described in any one of claims 1 to 13, wherein the first concave mirror comprises a body made of resin and a reflective layer on a surface of the body corresponding to the first reflective surface, and the second concave mirror comprises a body made of resin and a reflective layer on a surface of the body corresponding to the second reflective surface.

15. A moving object comprising the floating image display device according to any one of claims 1 to 14.

Images