Aerial Image Display Device

Abstract

The present invention provides an aerial image display device that can display aerial images with higher resolution than conventional devices. [Solution] An aerial image display device comprising: an image forming unit that emits a first image light; an optical element that transmits a portion of the incident light and reflects the remainder to form a second image light separated from the first image light; a light-gathering unit that focuses a portion of the second image light; a first retroreflective element provided at the light-gathering position of the light-gathering unit; and a second retroreflective element to which the remainder of the second image light is incident. The light-gathering unit comprises a light-gathering optical system that focuses a portion of the second image light and a support that supports the light-gathering optical system. The light-gathering optical system forms a first aerial image by imaging the second image light incident on itself onto the surface of the first retroreflective element and by imaging the second image light reflected by the first retroreflective element. The second retroreflective element overlaps with the support in the field of view as seen from the optical element side and retroreflectively reflects the second image light incident on itself to form a second aerial image.

Description

Technical Field

[0001] The present invention relates to an aerial image display device.

Background Art

[0002] Conventionally, display devices that display images or videos in the air have attracted attention as non-contact user interfaces and digital signage that provide a high sense of presence. In the following description, an image or video displayed in the air is referred to as an "aerial image". Also, a display device capable of displaying an aerial image is referred to as an "aerial image display device".

[0003] As an aerial image display device, a configuration using a retroreflective element is known (see, for example, Patent Document 1). In the aerial image display device described in Patent Document 1, an image displayed on the display device is reflected by an optical element having a beam splitter function, then incident on a retroreflective element, and a retroreflected light beam that exits in the same direction as the incident light beam is transmitted through the optical element having the beam splitter function to form an aerial image.

[0004] However, in the aerial image display device described in Patent Document 1, it is known that the resolution of the displayed image tends to decrease due to the characteristics of the retroreflective element.

[0005] Therefore, in order to achieve high resolution, a configuration using an optical element (such as a lens) having a condensing function is known (see Patent Document 2). In Patent Document 2, an image displayed on the display device is incident on the reflection surface of the retroreflective element through an optical element having a condensing function, so that it is incident on a relatively narrow range on the reflection surface of the retroreflective element. In Patent Document 2, it is stated that the aerial image can be made high-resolution by the above configuration.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, as shown in Patent Document 2, simply installing an optical element (such as a lens) with a light-gathering function has limited effect on improving resolution, and there remains the problem that resolution may not improve under certain conditions. Therefore, there was a need for a display device that could reliably produce high-resolution aerial images.

[0008] The present invention has been made in view of these circumstances, and aims to provide an aerial image display device that can display aerial images with higher resolution than conventional devices, and that achieves an expanded aerial display area and a wider field of view while exhibiting optimal imaging performance for the light-gathering optical element by using multiple retroreflective elements. [Means for solving the problem]

[0009] To solve the above problems, one aspect of the present invention includes the following aspects.

[0010] [1] An aerial image display device comprising: an image forming unit that emits a first image light; an optical element that transmits a portion of the incident light and reflects the remainder to form a second image light separated from the first image light; a focusing optical system that focuses a portion of the second image light; a first retroreflective element provided at the focusing position of the focusing optical system; and a second retroreflective element to which the remainder of the second image light is incident, wherein the focusing optical system forms a first aerial image by imaging the second image light incident on itself onto the surface of the first retroreflective element and by imaging the second image light reflected by the first retroreflective element, and the second retroreflective element retroreflectively reflects the second image light incident on itself to form a second aerial image.

[0011] [2] The aerial image display device according to [1], wherein the optical element is a reflective polarizer.

[0012] [3] The aerial image display device according to [2], having a quarter-wave plate in the optical path between the first retroreflective element and the focusing optical system.

[0013] [4] An aerial image display device according to [2] or [3], having an aerial image display device according to [2] or [3], wherein the optical element has an absorbing polarizing plate on the optical path opposite to the focusing optical system that absorbs polarization in the direction of vibration reflected by the optical element.

[0014] [5] The aerial image display device according to any one of [1] to [3], wherein the optical axis of the focusing optical system is inclined with respect to the principal ray axis of the second image light incident on the focusing optical system.

[0015] [6] The aerial image display device according to [5], having an anti-reflective plate in the optical path between the first retroreflective element and the focusing optical system.

[0016] [7] The aerial image display device according to any one of [1] to [3], wherein the focusing optical system causes a portion of the second image light to be reduced and imaged onto the first retroreflective element.

[0017] [8] An aerial image display device according to any one of [1] to [3], further comprising a third retroreflective element into which a third image light, which is the remainder obtained when the second image light is separated from the first image light, is incident.

[0018] [9] The aerial image display device according to any one of the items [1] to [3], wherein the optical element emits the first image light transmitted through the optical element as a second image light.

[0019]

[10] The aerial image display device according to any one of the items [1] to [9], wherein the second retroreflective element is positioned closer to the optical element than the first retroreflective element in the field of view as seen from the optical element side.

[0020]

[11] An aerial image display device according to

[10] , having a support member for supporting the light condensing optical system, wherein the second retroreflective element overlaps with the support member in the field of view as viewed from the optical element side.

[0021]

[12] An aerial image display device according to any one of [1] to

[11] , having a second light condensing optical system that forms an image of the second image light incident on itself on the surface of the second retroreflective element and forms a second aerial image by forming an image of the second image light reflected by the second retroreflective element.

Advantages of the Invention

[0022] According to the present invention, it is possible to provide an aerial image display device that can display an aerial image with higher resolution than before and can realize an enlargement of the aerial display area and a wider viewing angle.

Brief Description of the Drawings

[0023] [Figure 1] FIG. 1 is an explanatory diagram showing an aerial image display device 10A according to the first embodiment. [Figure 2] FIG. 2 is an explanatory diagram for explaining problems occurring in the retroreflective element. [Figure 3] FIG. 3 is an explanatory diagram for explaining the effects of the aerial image display device 10A. [[ID=2,7]] [Figure 4] FIG. 4 is an explanatory diagram showing an aerial image display device, 10B according to a modification. [Figure 5] FIG. 5 is an explanatory diagram of an aerial image display device 10C according to the second embodiment. [Figure 6] FIG. 6 is an explanatory diagram of an aerial image display device 10D according to the third embodiment. [Figure 7] FIG. 7 is an explanatory diagram of an aerial image display device 10E according to the fourth embodiment. <00001,05>FIG. 8 is an explanatory diagram of an aerial image display device 10F according to the fifth embodiment. [Figure 9] FIG. 9 is an explanatory diagram of an aerial image display device 10G according to the sixth embodiment.

Mode for Carrying Out the Invention

[0024] [First Embodiment] The aerial image display device according to the first embodiment will be described below with reference to Figures 1 to 4. Note that in all the following drawings, the dimensions and proportions of each component have been appropriately altered for clarity.

[0025] Figure 1 is an explanatory diagram showing an aerial image display device 10A according to the first embodiment. The aerial image display device 10A includes an image forming unit 1, an optical element 2, a light concentrating unit 3, a first retroreflective element 4A, and second retroreflective elements 4B, 4C. The aerial image display device 10A forms a second image light L2 from a first image light L1 emitted from the image forming unit 1, and forms an aerial image AI by imaging the second image light L2 in the air.

[0026] <Image Forming Section> The image forming unit 1 has a plurality of pixels P1 that emit a first image light L1. The plurality of pixels P1 are arranged, for example, in a matrix, and by emitting the first image light L1, they form the original image I1 of the aerial image AI.

[0027] The image forming unit 1 can employ various configurations as long as it is capable of emitting the first image light L1. For example, the image forming unit 1 may be a self-emissive display panel (display device), or a known display device formed by a combination of a light source and a light modulator that modulates the light emitted from the light source may be used.

[0028] As the light source for the above-mentioned display device, known light sources such as mercury lamps, laser light sources, and LEDs can be used. As the optical modulation device for the above-mentioned display device, known optical modulation devices such as liquid crystal panels and DMDs (Digital Micro-mirror Devices) can be used.

[0029] The first image light L1 emitted by the image forming unit 1 may be monochromatic, or it may be multiple colors including, for example, the three primary colors red (R), green (G), and blue (B). If the first image light L1 includes multiple colors, the image forming unit 1 may be a single display device, or it may use a different display device for each color of light emitted, and emit each color of light superimposed on the optical path.

[0030] The image forming unit 1 may have a projection optical system (not shown).

[0031] The first image light L1 emitted from the image forming unit 1 is incident on the optical element 2. Figure 1 shows the first image light L1 emitted from one pixel (point light source) of the image forming unit 1.

[0032] <Optical elements> The optical element 2 has the function of transmitting a portion of the incident light and reflecting the remainder. The optical element 2 divides the first image light L1 emitted from the image forming unit 1 to form the second image light L2. In the aerial image display device 10A, the light component reflected by the optical element 2 is used as the second image light L2.

[0033] As the optical element 2, known beam splitters and reflective polarizers can be used.

[0034] The second image light L2 emitted from the optical element 2 is incident on the light-gathering unit 3.

[0035] <Light-gathering section> The light-gathering unit 3 is an optical system that magnifies and focuses the second image light L2 incident from the optical element 2 side, and also magnifies the light incident from the retroreflective element 4 side. The light-gathering unit 3 focuses a portion of the second image light L2 emitted from the optical element 2 toward the first retroreflective element 4A. In Figure 1, the light-gathering unit 3 is shown focusing the image light L21 toward the first retroreflective element 4A.

[0036] The light-gathering unit 3 includes a light-gathering optical system 31 that focuses a portion of the second image light L2, and a support member 32 that supports the light-gathering optical system 31.

[0037] The focusing optical system 31 focuses a portion of the second image light L2 (image light L21) toward the first retroreflective element 4A and forms an image on the surface (reflective surface 4a) of the first retroreflective element 4A.

[0038] The focusing optical system 31 may consist of a single optical element or multiple optical elements (multiple lenses). Furthermore, the focusing optical system 31 can employ a lens array.

[0039] The support 32 is positioned on the axial outer circumference of the condensing optical system 31 and supports the condensing optical system 31. Examples of the support 32 include well-known lens barrels and lens brackets.

[0040] <First and second retroreflective elements> The first retroreflective element 4A and the second retroreflective elements 4B and 4C are all optical elements that retroreflect the incident second image light L2. The first retroreflective element 4A is located at the focusing position of the focusing optical system 31 of the focusing unit 3. The second retroreflective elements 4B and 4C are located closer to the optical element 2 than the first retroreflective element 4A in the field of view as seen from the optical element 2 side, and are located at the position where the remaining portion of the second image light L2 that did not enter the focusing unit 3 (image light L22) is incident.

[0041] The first retroreflective element 4A and the second retroreflective elements 4B and 4C each have a plurality of cells 41 that perform retroreflection.

[0042] Known configurations can be used for the first retroreflective element 4A and the second retroreflective elements 4B and 4C. These retroreflective elements can, for example, have a configuration in which a large number of corner cubes are arranged on the reflective surface (corner cube type or prism lens type), or a configuration in which a large number of glass beads are arranged on the reflective surface (glass bead type).

[0043] The multiple corner cubes and glass beads of the retroreflective element each correspond to cells that perform retroreflection in the retroreflective element. A corner cube configuration is preferred for the first retroreflective element 4A and the second retroreflective elements 4B and 4C. In Figure 1, the first retroreflective element 4A and the second retroreflective elements 4B and 4C are shown as being of the corner cube type.

[0044] The first retroreflective element 4A and the second retroreflective elements 4B and 4C may have the same configuration or different configurations.

[0045] The image light L21 reflected by the first retroreflective element 4A is again incident on the focusing optical system 31. At this time, the image light L21 retroreflectively reflected by the first retroreflective element 4A passes through the focusing optical system 31 from the retroreflective element 4 side, following the same optical path as when it passed through the focusing optical system 31 from the optical element 2 side. If the focusing optical system 31 has lens aberrations, the aberration when passing through the focusing optical system 31 from the optical element 2 side and the aberration when passing through the focusing optical system 31 from the first retroreflective element 4A side cancel each other out. As a result, the lens aberrations in the focusing optical system 31 are reduced in the second image light L2 emitted from the focusing optical system 31.

[0046] The image light L21, focused by the focusing optical system 31, is incident on the optical element 2. Of the image light L21 incident on the optical element 2, the component that passes through the optical element 2 is imaged at the focusing position of the focusing optical system 31.

[0047] Furthermore, the image light L22 reflected by the second retroreflective elements 4B and 4C enters the optical element 2. Of the image light L22 that enters the optical element 2, the component that passes through the optical element 2 is imaged at a spatial position symmetrical to the image forming unit 1 across the optical element 2.

[0048] The image light L21 formed by the light-gathering optical system 31 and the image light L22 formed by the second retroreflective elements 4B and 4C form a single aerial image AI.

[0049] The user U of the device can acquire various information by viewing the aerial image AI.

[0050] Figure 2 is an explanatory diagram illustrating the problems that arise in retroreflective elements. Figure 2 shows a perspective view (Figure 2(a)) and a cross-sectional view (Figure 2(b)) of cell 41 of a corner cube-shaped retroreflective element 4. Similar problems also arise in retroreflective elements in which numerous glass beads are arranged on the reflective surface.

[0051] As shown in Figure 2(a), the cell 41 of the retroreflective element 4 is a triangular pyramidal shape with three reflective surfaces 41a, 41b, and 41c. Each of the reflective surfaces 41a, 41b, and 41c is a right-angled triangle, and the right angles of each reflective surface meet to form the vertex of the triangular pyramidal shape.

[0052] The incident light IL entering such a cell 41 is reflected sequentially by, for example, the reflective surfaces 41a, 41b, and 41c, and the reflected light RL is emitted in the same direction as the incident light IL. At this time, the optical path of the incident light IL and the optical path of the reflected light RL are shifted (optical path shift) due to reflections occurring within the cell 41. The amount of shift W1 between the incident light IL and the reflected light RL is larger the larger the cell 41 is.

[0053] On the other hand, as shown in Figure 2(b), when incident light IL is incident on the cell 41 of the retroreflective element 4, the incident light IL is diffracted by the cell 41 when it is reflected. As a result, the reflected light RL emitted from the cell 41 has a broadened shape as diffracted light. The amount of broadening W2 of the reflected light RL depends on the diffraction angle, so it becomes larger as the cell 41 becomes smaller.

[0054] In conventional aerial image display devices with retroreflective elements, the resolution of the aerial image was reduced due to these optical path shifts and diffractions.

[0055] In contrast, in the aerial image display device 10A, the diffraction distance, which is the distance from the image forming unit 1 to the retroreflective element 4, is shortened optically by using the focusing optical system 31 to focus a portion of the second image light L2 (image light L21) onto the first retroreflective element 4A.

[0056] Furthermore, by positioning the second retroreflective elements 4B and 4C closer to the optical element 2 than the first retroreflective element 4A in the field of view from the optical element 2 side, the diffraction distance, which is the distance from the image forming unit 1 to the retroreflective element 4, is shortened.

[0057] As a result, the aerial image display device 10A can improve the resolution of both the image light L21 that passes through the focusing optical system 31 and the image light L22 that does not pass through the focusing optical system 31, thereby forming a high-resolution aerial image AI.

[0058] Furthermore, the aerial image display device 10A uses a focusing optical system 31 that magnifies and focuses the image light L21 incident from the optical element 2 side, while simultaneously reducing and focusing the light incident from the first retroreflective element 4A side. As a result, the focusing lens 3 acts as a reduction optical system for the retroreflective image light L21, suppressing the ray shift caused by the size (pitch size) of the cells 41 of the retroreflective element 4, as shown in Figure 2(a). This suppresses the spreading of the point image formed by the focusing optical system 31, thus resolving the issue of reduced resolution.

[0059] Furthermore, as shown in Figure 2(b), the diffracted and scattered light generated on the retroreflective element 4 is focused to the position of the aerial image by the focusing optical system 31. This eliminates the problem of reduced resolution caused by the spreading of light generated by the diffracted light etc. generated by the retroreflective element 4.

[0060] Furthermore, the size of the original image I1 may be changed by optical elements arranged in the optical path from the image forming unit 1 to the retroreflective element 4, so as to satisfy the following equation (A). [Pixel size] × α ≥ [Cell size] ... (A) (In the formula, α represents the magnification factor due to the optical elements arranged in the optical path from the image forming unit 1 to the first retroreflective element 4A.)

[0061] In other words, as shown in Figure 1, when the focusing optical system 31 forms an image of the image light L21 (intermediate image I2) on the reflective surface 4a of the first retroreflective element 4A, the pixels P2 of the intermediate image I2 are set to be equal to or greater than the size of the cell 41.

[0062] Here, "pixel size" refers to the width of a pixel in the direction of the subpixel arrangement when one pixel is formed by three subpixels of RGB colors. "Subpixel size" refers to the width of a subpixel in the direction of the above arrangement. Furthermore, "cell size" refers to half the size of one side of the cell if the retroreflective element is a corner cube type, the size of one side of the cell if it is a full corner cube type, and the diameter of the bead if it is a bead type.

[0063] Figure 3 is an explanatory diagram illustrating the effects of the aerial image display device 10A. Figure 3(a) is a diagram comparing the size of a pixel P1 in the image forming unit 1 (original image I1) with that of a cell 41, and Figure 3(b) is a diagram comparing the size of a pixel P2 in the intermediate image I2 with that of a cell 41. Pixel P1 has RGB subpixels SP1, and pixel P2 has RGB subpixels SP2.

[0064] For example, as shown in Figure 3(a), when comparing the size of a pixel P1 in the image forming unit 1 with the size of a cell 41, the device configuration is such that the cell 41 is larger than the pixel P1 ([size of pixel P1 Wa] < [size of cell 41 Wb]). If the image light emitted from the pixel P1 of the image forming unit 1 enters the cell 41 while maintaining the size relationship as shown in Figure 3(a), there is a risk that the cell 41 will experience an optical path shift greater than the size of the pixel P1. In that case, problems such as the image light displaying a certain pixel overlapping with the image light displaying adjacent pixels may occur, leading to a decrease in the resolution of the resulting aerial image.

[0065] On the other hand, as shown in Figure 3(b), the first image light L1 and the second image light L2 are magnified by the optical elements arranged in the optical path from the image forming unit 1 to the retroreflective element 4, resulting in the pixels P2 of the intermediate image I2 being equal to or larger than the size of the cell 41 ([size of pixel P2 Wc] ≥ ​​[size of cell 41 Wb]). The [size of pixel P2 Wc] can be determined from the size of pixel P1 and the magnification ratio of the optical elements arranged in the optical path from the image forming unit 1 to the first retroreflective element 4A.

[0066] In this case, even if the image light L21 undergoes a path shift in cell 41, the shift in image light L21 is likely to remain within a single pixel. Therefore, problems such as the image light displaying one pixel overlapping with the image light displaying adjacent pixels are less likely to occur.

[0067] For similar reasons, if pixel P1 has multiple sub-pixels SP1, it is preferable that it satisfies the following equation (B). [Subpixel size] × α ≥ [Cell size] ... (B) (In the formula, α represents the magnification factor due to the optical elements arranged in the optical path from the image forming unit 1 to the first retroreflective element 4A.)

[0068] If equation (B) above is satisfied, even if the image light L21 undergoes an optical path shift in cell 41, the shift in the image light L21 is likely to remain within a single subpixel. Therefore, problems such as the image light used to display one pixel overlapping with the image light used to display an adjacent pixel are less likely to occur.

[0069] Furthermore, the diffusion of light generated in the retroreflective element, such as diffraction due to aperture limitation of the retroreflective element 4 and scattering at the vertices and edges of the prism structure, can be focused into the aerial image AI by the focusing optical system. In other words, the cell 41 constituting the retroreflective element can be made smaller. It should be noted that in a normal aerial image display device, it is known that, contrary to the aerial image display device 10A, it is better to make the cell larger in order to suppress the diffusion of light due to diffraction.

[0070] Furthermore, in the aerial image display device 10A, the second retroreflective elements 4B and 4C are positioned to overlap with the support 32 in the field of view as seen from the optical element 2 side. This allows the second image light L2, which is irradiated onto the support 32 that does not transmit light, to be used in forming the aerial image AI.

[0071] The aerial image formed using image light L21 has a higher resolution than the aerial image formed using image light L22. Therefore, the aerial image AI displayed by the aerial image display device 10A has a display area capable of displaying high resolution and a display area with relatively lower resolution.

[0072] Therefore, with the aerial image display device 10A configured as described above, it is possible to display aerial image AI that includes a higher resolution display area than conventional displays and allows for diverse representations. The first retroreflective element 4A and the second retroreflective elements 4B and 4C should be selected appropriately depending on the content of the aerial image to be displayed.

[0073] Figure 4 is an explanatory diagram showing a modified aerial image display device 10B. The light-gathering optical system 31 (light-gathering unit 3) of the aerial image display device 10B reduces and combines the image light L21 on the surface of the first retroreflective element 4A. With this configuration, the aerial image display device 10B can reduce the footprint of the entire optical system and thus miniaturize the device.

[0074] [Second Embodiment] Figure 5 is an explanatory diagram of the aerial image display device 10C according to the second embodiment. In the following embodiments, components common to the previously described embodiments are denoted by the same reference numerals, and detailed descriptions are omitted.

[0075] The aerial image display device 10C includes an image forming unit 1, an optical element 2, a light concentrating unit 3, a first retroreflective element 4A, and second retroreflective elements 4B and 4C. In the aerial image display device 10C, the light component transmitted through the optical element 2 is used as the second image light L2.

[0076] A portion of the second image light L2 (image light L21) emitted from the optical element 2 is imaged onto the reflective surface 4a of the first retroreflective element 4A via the light-gathering unit 3. The image light L21 is also retroreflective by the first retroreflective element 4A and incident on the light-gathering unit 3.

[0077] The image light L21 focused by the light-gathering unit 3 is incident on the optical element 2. Of the image light L21 incident on the optical element 2, the component reflected by the optical element 2 is imaged at the focusing position of the light-gathering unit 3.

[0078] Furthermore, the image light L22 reflected by the second retroreflective elements 4B and 4C enters the optical element 2. Of the image light L22 that enters the optical element 2, the component that passes through the optical element 2 is imaged at a spatial position symmetrical to the image forming unit 1 across the optical element 2.

[0079] The image light L21 formed by the light-gathering optical system 31 and the image light L22 formed by the second retroreflective elements 4B and 4C form a single aerial image AI.

[0080] The user U of the device can acquire various information by viewing the aerial image AI. In addition, the user U will also view the background B of the optical element 2 through the optical element 2. In other words, the aerial image display device 10C is a so-called see-through type display device, which allows the user U to view an image in which the aerial image AI and background B are superimposed.

[0081] This aerial image display device 10C has a higher resolution display area than conventional displays, enabling the display of aerial images AI capable of diverse expressions. Furthermore, by allowing the user U to view the image including the background B, richer image expression becomes possible.

[0082] [Third Embodiment] Figure 6 is an explanatory diagram of the aerial image display device 10D according to the third embodiment. The aerial image display device 10D includes an image forming unit 1, an optical element 20, a light concentrating unit 3, a first retroreflective element 4A, second retroreflective elements 4B, 4C, a quarter-wave plate 5, and an absorbing polarizing plate 6.

[0083] The optical element 20 is a reflective polarizer. The optical element 20 separates the unpolarized first image light L1 into s-polarized and p-polarized light, transmits the s-polarized light, and reflects the p-polarized light as the second image light L2. If the image forming unit 1 is a liquid crystal panel and the first image light L1 is polarized light, it is preferable that the image forming unit 1 emits p-polarized light as the first image light L1.

[0084] The quarter-wave plate 5 is positioned to cover the reflective surface 4a of the first retroreflective element 4A. A known configuration can be used for the quarter-wave plate 5.

[0085] The quarter-wave plate 5 converts the incident second image light L2 (image light L21) from linearly polarized (p-polarized) to circularly polarized. The second image light L2, converted to circular polarization, is reflected an odd number of times (three times for a corner cube type, once for a glass bead type) at the fixed end of the cell 41 of the first retroreflective element 4A, and its phase shifts by 180°.

[0086] The image light L21 retroreflective within cell 41 is emitted from the first retroreflective element 4A, enters the quarter-wave plate 5 again, and is converted from circularly polarized light to linearly polarized light. At this time, because the phase of the image light L21 has shifted due to reflection within cell 41, it is converted from the original p-polarized light to s-polarized light.

[0087] The s-polarized image light L21 is focused by the light-gathering unit 3 and incident on the optical element 2. The image light L21 incident on the optical element 2 passes through the optical element 2 and forms an image at the focusing position of the light-gathering optical system 31, forming an aerial image AI.

[0088] The absorbing polarizing plate 6 is positioned on the opposite side of the optical element 2 from the light-gathering section 3. The absorbing polarizing plate 6 absorbs the polarization in the direction of vibration reflected by the optical element 20, i.e., p-polarized light, and transmits s-polarized light.

[0089] As described above, the optical element 20 is a reflective polarizer and has the function of reflecting p-polarized light and transmitting s-polarized light. However, in the aerial image display device 10D, the light is incident on the optical element 20 at an oblique angle, so the optical element 20 may not perform as designed and may transmit p-polarized light as well. In this case, by placing the absorbing polarizer 6, which absorbs p-polarized light, on the opposite side of the optical element 2 from the light-gathering unit 3, i.e., on the user U side, the p-polarized light that would otherwise pass through the optical element 20 can be absorbed by the absorbing polarizer 6.

[0090] According to the aerial image display device 10D with this configuration, it is possible to display aerial images AI that include a higher resolution display area than conventional devices and can express a variety of things, while also suppressing light loss in the optical path and improving visibility.

[0091] [Fourth Embodiment] Figure 7 is an explanatory diagram of the aerial image display device 10E according to the fourth embodiment. In the aerial image display device 10E, the optical axis 3ax of the light-gathering unit 3 is inclined with respect to the principal ray axis of the image light L21 incident on the light-gathering unit 3. In addition, the direction of the normal 4ax of the surface (reflective surface 4a) of the first retroreflective element 4A is inclined with respect to the principal ray axis of the image light L21 incident on the first retroreflective element 4A.

[0092] Furthermore, in the aerial image display device 10E, an anti-reflective plate 7 is provided in the optical path between the first retroreflective element 4A and the light-gathering unit 3. This prevents surface reflection of the first retroreflective element 4A, suppresses the generation of stray light, and improves visibility.

[0093] According to the aerial image display device 10E with this configuration, it is possible to display aerial images AI that include a higher resolution display area than conventional devices and can express a variety of views. In addition, it is possible to suppress the generation of stray light and improve visibility.

[0094] [Fifth Embodiment] Figure 8 is an explanatory diagram of the aerial image display device 10F according to the fifth embodiment. In the aerial image display device 10F, a third retroreflective element 4D is positioned at the location where the third image light L3, which is the remainder after the second image light L2 is separated from the first image light L1 in the optical element 2, is incident. The third retroreflective element 4D can have the same configuration as the first retroreflective element 4A and the second retroreflective elements 4B and 4C.

[0095] The third image light L3, incident on the third retroreflective element 4D, is retroreflective and irradiates the optical element 2. Of the third image light L3 incident on the optical element 2, the component reflected by the optical element 2 forms an image at a spatial position symmetric to the image forming unit 1 across the optical element 2. The image formed by the third image light L3 is superimposed with the images formed by the image lights L21 and L22 to form an aerial image AI.

[0096] According to the aerial image display device 10F configured as described above, it is possible to display aerial image AI that includes a higher resolution display area than conventional devices and allows for diverse representations.

[0097] [Sixth Embodiment] Figure 9 is an explanatory diagram of the aerial image display device 10G according to the sixth embodiment. The aerial image display device 10G has focusing optical systems 31A, 31B, and 31C. The focusing optical system 31A corresponds to the focusing optical system 31 described above and performs the same function.

[0098] The focusing optical systems 31B and 31C correspond to the "second focusing optical system" in this invention. The focusing optical systems 31B and 31C are supported by support members 32B and 32C, respectively. The support members 32B and 32C can have the same configuration as the support member 32 described above.

[0099] The focusing optical systems 31B and 31C each focus the second image light (image light L22) incident on them onto the surfaces of the second retroreflective elements 4B and 4C, and also focus the image light L22 reflected by 4B and 4C onto the second retroreflective elements to form a part of the aerial image AI (the second aerial image). The focusing optical systems 31B and 31C can have the same configuration as the focusing optical system 31 described above.

[0100] Retroreflective elements 33A, 33B, and 33C are positioned on the optical element 2 side of the support members 32A, 32B, and 32C, respectively. In the field of view from the optical element 2 side, the retroreflective elements 33A, 33B, and 33C overlap with the support members 32A, 32B, and 32C, respectively.

[0101] Furthermore, the focusing optical system 31B, the support 32B, and the retroreflective element 33B are positioned closer to the optical element 2 than the focusing optical system 31A, the support 32A, and the retroreflective element 33A. In addition, the focusing optical system 31A, the support 32A, and the retroreflective element 33A are positioned closer to the optical element 2 than the focusing optical system 31C, the support 32C, and the retroreflective element 33C.

[0102] In the field of view from the optical element 2 side, a portion of the support 32B and retroreflective element 33B overlaps with a portion of the support 32A and retroreflective element 33A. Also, a portion of the support 32B and retroreflective element 33B overlaps with a portion of the support 32C and retroreflective element 33C.

[0103] In this way, each support overlaps with the others, and the retroreflective elements are positioned overlapping with the support, thereby suitably reflecting the second image light L2 incident on the support towards the user U, and forming an aerial image AI.

[0104] The aerial image display device 10G with the above configuration allows for the display of aerial images (AI) with a higher resolution display area than conventional devices, enabling diverse representations. The functions of the focusing optical systems 31B and 31C enable the formation of high-resolution aerial images with respect to the image light L22. Furthermore, by using multiple focusing optical systems, high-resolution aerial images can be observed from multiple viewpoints.

[0105] The aerial image display devices of each of the embodiments described above can display aerial images with appropriate resolution depending on the displayed information. For example, they can form an aerial image using image light L21 for information requiring high resolution, such as text or detailed diagrams, and use image light L22 for areas where relatively high resolution is not required, such as background patterns. Taking advantage of these characteristics, applications as high-resolution aerial signage can be expected.

[0106] In addition, it will be possible to display high-resolution aerial images for information displays such as traffic information, map information, facility guides, and explanations of exhibits, as well as for content displays in interpersonal services such as entertainment, nursing care, and medical care.

[0107] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design, specifications, etc., without departing from the spirit of the present invention.

[0108] Furthermore, each optical element shown in the above embodiment can be replaced with an optically equivalent element. For example, although a biconvex lens was shown as the focusing lens, a concave mirror may be used as the optical element with a focusing function. In addition, a light guide optical system may be appropriately provided for bending and curving the optical path. [Explanation of Symbols]

[0109] 1…Image forming unit, 2,20…Optical elements, 3…Light concentrating unit, 3ax…Optical axis, 4…Retroreflective element, 4A…First retroreflective element, 4D…Third retroreflective element, 4B…Second retroreflective element, 5…Waveplate, 6…Absorption polarizer, 7…Anti-reflective plate, 10A,10B,10C,10D,10E,10F…Airborne image display device, 31…Light concentrating optical system, 32…Support, AI…Airborne image, L1…First image light, L2…Second image light, L3…Third image light, L21,L22…Image light

Claims

1. An image forming unit that emits a first image light, An optical element that transmits a portion of the incident light and reflects the remainder to form a second image light separated from the first image light, A focusing optical system that focuses a portion of the second image light, A first retroreflective element provided at the light-gathering position of the light-gathering optical system, The system comprises a second retroreflective element into which the remainder of the second image light is incident, The light-gathering optical system forms a first aerial image by imaging the second image light incident on itself onto the surface of the first retroreflective element, and by imaging the second image light reflected by the first retroreflective element. The second retroreflective element retroreflectively reflects the second image light incident upon itself to form a second aerial image display device.

2. The aerial image display device according to claim 1, wherein the optical element is a reflective polarizing plate.

3. The aerial image display device according to claim 2, further comprising a quarter-wave plate in the optical path between the first retroreflective element and the focusing optical system.

4. The aerial image display device according to claim 2 or 3, further comprising an absorbing polarizing plate on the optical path opposite to the condensing optical system relative to the optical element, which absorbs polarization in the vibration direction reflected by the optical element.

5. The aerial image display device according to any one of claims 1 to 3, wherein the optical axis of the focusing optical system is inclined with respect to the principal ray axis of the second image light incident on the focusing optical system.

6. The aerial image display device according to claim 5, further comprising an anti-reflective plate in the optical path between the first retroreflective element and the focusing optical system.

7. The aerial image display device according to any one of claims 1 to 3, wherein the light-gathering optical system causes a portion of the second image light to be reduced and imaged onto the first retroreflective element.

8. The aerial image display device according to any one of claims 1 to 3, further comprising a third retroreflective element into which the third image light, which is the remainder after the second image light has been separated from the first image light, is incident.

9. The aerial image display device according to any one of claims 1 to 3, wherein the optical element emits the first image light transmitted through the optical element as a second image light.

10. The aerial image display device according to any one of claims 1 to 3, wherein the second retroreflective element is positioned closer to the optical element than the first retroreflective element in the field of view as seen from the optical element side.

11. Having a support for the aforementioned light-gathering optical system, The aerial image display device according to claim 10, wherein the second retroreflective element overlaps with the support in the field of view as seen from the optical element side.

12. An aerial image display device according to any one of claims 1 to 3, further comprising a second focusing optical system that images the second image light incident on itself onto the surface of the second retroreflective element and images the second image light reflected by the second retroreflective element to form a second aerial image.

Images