Display device

Abstract

[Project] Provide a display device that makes it difficult to show the internal structure. [Solution] The display device (100) of the present invention comprises a housing (110), a display (120) housed within the housing (110), a polarizing beam splitter (130), an ND filter (140), a λ / 4 plate (150), and a retroreflective material (160). A λ / 4 plate (150) is placed on the surface of the retroreflective material (160), and an ND filter (140) is placed on the surface of the λ / 4 plate (150). Unwanted light (Lb) that does not contribute to the formation of an aerial image (P) output from the display (120) is sensitized by the ND filter (140).

Description

Technology Field

[0001] The present invention relates to a display device that displays an aerial image by retroreflection. Background Technology

[0002] Aerial Imaging by Retro-Reflection (AIRR) is known. The principle of aerial imaging (or aerial image) display using retro-reflection is to reflect light generated from a light source in the direction of a retro-reflective material by a mirror, and to re-image the light by transmitting a portion of the light that returns to the mirror. For this reason, half mirrors with reduced reflectivity or polarizing beam splitters are used as mirrors (e.g., Patent Document 1). Prior art literature

[0003] Japanese Patent No. 7604079 The problem to be solved

[0004] FIG. 1(A) is a diagram showing the schematic configuration of a conventional display device for displaying an aerial image. The display device (10) is configured to include, for example, a display (30), a polarizing beam splitter (40), a λ / 4 plate (50), and a retroreflective material (60) within a housing (20), such as a casing.

[0005] The display (30) outputs the original image of the aerial image (P), and the polarizing beam splitter (40) reflects the incident light of the original image toward the retroreflective material (60). The λ / 4 plate (50) is a phase difference film that generates a phase difference of λ / 4 and is attached to the surface of the retroreflective material (60). The light reflected from the polarizing beam splitter (40) passes through the λ / 4 plate (50) and is retroreflected from the retroreflective material (60) in the same direction as the incident light, and the retroreflected light passes through the λ / 4 plate (50) again and then passes through the polarizing beam splitter (40) to form the aerial image (P).

[0006] Here, among the light output from the display (30), the light (La) reflected from the polarizing beam splitter (40) becomes light (La') passing through the light path of the λ / 4 plate (50), retroreflective material (60), λ / 4 plate (50), and polarizing beam splitter (40), thereby forming an aerial image (P). Meanwhile, among the light output from the display (30) in an oblique direction, there is also light (Lb) that does not enter the polarizing beam splitter (40) but enters directly into the λ / 4 plate (50), and such light (Lb) becomes, for example, light (Lb') reflected from the surface of the λ / 4 plate (50) and does not contribute to forming an aerial image (P). When such light (Lb') reaches the eyes of the observer (U), the internal structure, such as the optical system inside the housing, appears bright, and there was a problem that the contrast of the aerial image (P) was reduced.

[0007] In addition, as shown in FIG. 1(B), among the light (Lc) incident on the retroreflective material (60) after passing through the λ / 4 plate (50), scattered light (Lc') is generated that is not retroreflected and is repeatedly reflected between the reflective part (metal layer of Al) (62) of the retroreflective material (60) and the λ / 4 plate (50). This scattered light (Lc') is also unnecessary light that does not contribute to the formation of an image in the air (P), and thus causes the same problem as above. In addition, light (La) exemplifies the desirable retroreflected light (La').

[0008] The present invention aims to solve these conventional problems and provide a display device that improves contrast in the air by making it difficult to see the internal structure. means of solving the problem

[0009] A display device according to the present invention is capable of displaying an aerial image using retroreflection, and comprises a light source, a polarizing beam splitter disposed at a position where light from the light source is incident, a retroreflective material, a λ / 4 plate disposed on the surface of the retroreflective material, and a photosensitive filter disposed on the surface of the λ / 4 plate, wherein the retroreflective material receives light reflected from the polarizing beam splitter through the photosensitive filter and the λ / 4 plate, and the polarizing beam splitter transmits light retroreflected from the retroreflective material through the λ / 4 plate and the photosensitive filter to form the aerial image.

[0010] Additionally, the display device according to the present invention is capable of displaying an aerial image using retroreflection and comprises a light source, a half mirror disposed at a position where light from the light source is incident, a retroreflective material, and a polarizing plate disposed on the surface of the retroreflective material. The retroreflective material receives light reflected from the half mirror through the polarizing plate, and the half mirror transmits light retroreflected from the retroreflective material through the polarizing plate to form the aerial image. Effects of the invention

[0011] According to the present invention, a photosensitive filter is placed on the surface of a λ / 4 plate, thereby reducing light that does not contribute to the formation of an aerial image from a light source, and thereby suppressing the bright appearance of the internal structure, so that the contrast between the aerial image and the background can be improved. Additionally, according to the present invention, a polarizing plate is placed on the surface of a retroreflective material, thereby reducing light that does not contribute to the formation of an aerial image from a light source, and thereby suppressing the bright appearance of the internal structure, so that the contrast between the aerial image and the background can be improved. Brief explanation of the drawing

[0012] FIG. 1(A) is a diagram showing the schematic configuration of a conventional display device for displaying an aerial image, and FIG. 1(B) is a diagram illustrating scattered light generated from a retroreflective material. FIG. 2 is a diagram showing the schematic configuration of a display device for displaying an aerial image according to the first embodiment of the present invention. FIG. 3(A) is a diagram illustrating the reduction of unwanted light when an ND filter is placed on a polarizing beam splitter of a conventional structure, and FIG. 3(B) illustrates the reduction of unwanted light according to the present embodiment. FIG. 4 is a diagram showing the schematic configuration of a display device for displaying an aerial image according to a second embodiment of the present invention. Specific details for implementing the invention

[0013] Next, embodiments of the present invention will be described. The display device according to the present embodiment displays an image in the air using retroreflection, while ensuring that the inside of the housing does not appear bright, thereby improving the external design of the display device and also improving the visibility and brightness of the image in the air. It should be noted that the drawings referenced in the following description of the embodiments include exaggerated representations to facilitate understanding of the invention and do not represent the actual shape or scale of the product.

[0014] Examples

[0015] Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a diagram showing the schematic configuration of a display device according to a first embodiment of the present invention. The display device (100) of the present embodiment is configured to include a housing (110), a display (120) as a light source disposed within the housing (110), a polarizing beam splitter (130), an ND filter (140), a λ / 4 plate (150), and a retroreflective material (160), and displays an aerial image (P) floating in the air from the housing (110).

[0016] The housing (110) is not particularly limited in shape or material, but is, for example, a rectangular casing and accommodates optical elements such as a display (120), a polarizing beam splitter (130), and a retroreflective material (160) in its internal space. On the upper surface of the housing (110), an opening or window (112) through which light from the polarizing beam splitter (130) passes is formed at a position facing the polarizing beam splitter (130). The opening (112) is appropriately selected according to the size of the aerial (P) or the display (120). Additionally, the opening (112) may be a cavity, or the opening (112) may be covered by a cover or sheet made of a material capable of transmitting light.

[0017] The display (120) is a light source for generating an original image of an aerial image (P). The display (120) is not particularly limited, but is, for example, an LED or organic EL display, a projector, an LED unit in which a plurality of LEDs are arranged two-dimensionally, etc. In the first embodiment, the display (120) outputs light that is generally linearly polarized toward the polarizing beam splitter (130). In addition, the angle formed by the normal (optical axis) of the display surface of the display (120) and the main surface of the polarizing beam splitter (130) is, for example, 45 degrees.

[0018] The polarizing beam splitter (130) selectively reflects a component of linear polarization vibrating in a certain direction and transmits a component orthogonal to said linear polarization component. The polarizing beam splitter (130) has a transmission axis set to reflect light received from the display (120) and, on the other hand, transmit light received from the retroreflective material (160).

[0019] The retroreflective material (160) is an optical element that reflects light in the same direction as the incident light, and its configuration is not particularly limited, but is composed of, for example, a triangular pyramidal retroreflective element, a full cube corner-shaped retroreflective element, etc. The retroreflective material (160) is, for example, a rectangular sheet-shaped or film-shaped member and is disposed on the bottom surface of the housing (110).

[0020] The λ / 4 plate (150) is an optical element in the form of a sheet or film that generates a phase difference of λ / 4 between incident light and output light. The λ / 4 plate (150) is, for example, attached to the retroreflective surface of the retroreflective material (160) or placed in close proximity to the surface of the retroreflective material (160). The λ / 4 plate (150), for example, emits light converted into circular polarization when incident with linearly polarized light vibrating in a certain direction, or emits light converted into linear polarization when incident with circularly polarized light.

[0021] The ND (Neutral Density) filter (140) is a photosensitive filter that evenly reduces light of all incident wavelengths. The ND filter (140) has a planar shape generally identical to that of the λ / 4 plate (150) and, for example, is attached to the surface of the λ / 4 plate (150) or placed in close proximity to the surface.

[0022] Next, the operation of the display device (100) of the present embodiment is described. The display (120) outputs an original image of the air (P), and the polarizing beam splitter (130) reflects the light of the original image incident from the display (120) toward the retroreflective material (160). The light reflected from the polarizing beam splitter (130) has its light intensity reduced by passing through the ND filter (140), and then passes through the λ / 4 plate (150) and is incident on the retroreflective material (160). The light incident on the retroreflective material (160) is retroreflected therein in the same direction as the incident light, and the retroreflected light passes through the λ / 4 plate (150) again and then passes through the ND filter (140) again to have its light intensity reduced. The retroreflected light passing through the ND filter (140) passes through the polarizing beam splitter (130) to form an aerial image (P).

[0023] Here, among the light output from the display (120), the light (La) incident on the polarizing beam splitter (130) is retroreflected from the retroreflective material (160) and is a desirable light (La') that forms an aerial image (P). Meanwhile, the light (Lb) output from the display (120) in an oblique direction and incident on the λ / 4 plate (150) without being incident on the polarizing beam splitter (130) is an unnecessary light that does not contribute to the formation of an aerial image (P). This light (Lb) becomes light (Lb') with reduced light intensity by passing through the ND filter (140) twice. Since the amount of light (Lb') is reduced, when an observer (U) observes an aerial image (P), even if the light (Lb') reaches the observer's (U) eyes, the internal structure of the housing (110) is suppressed from appearing bright, thereby improving the contrast between the aerial image (P) and its background. Additionally, although not shown here, scattered light generated from a retroreflective material (160) as shown in FIG. 1 (B) is also extinguished by the ND filter (140), so the internal structure of the housing (110) is suppressed from appearing bright.

[0024] In the above embodiment, the ND filter (140) is configured to be placed on the upper surface of the λ / 4 plate (150), but it is not limited thereto, and the ND filter (140) may be placed on the lower surface (or the reverse surface) of the λ / 4 plate (150). That is, the ND filter (140) is placed between the λ / 4 plate (150) and the retroreflective material (160). Even if the ND filter (140) is placed on the lower surface of the λ / 4 plate (150), the same effect as in the above embodiment can be obtained, and unwanted light (Lb) that does not form an image of the aerial image (P) is reduced by the ND filter (140), so that the internal structure of the housing (110) is not seen brightly, and the contrast between the aerial image (P) and its background is improved. In addition, the method of mounting the ND filter (140) is arbitrary; for example, the ND filter (140) may be attached to the surface of the retroreflective material (160), and the λ / 4 plate (150) may be attached to the surface of the ND filter (140).

[0025] FIG. 3(A) shows the reduction of unwanted light when an ND filter is mounted on a polarizing beam splitter of a conventional structure, and FIG. 3(B) shows the reduction of unwanted light when an ND filter is mounted on the surface of a λ / 4 plate as in the present embodiment.

[0026] In a conventional structure, a λ / 4 plate (210) is placed on the surface of a retroreflector (200), a polarizing beam splitter (220) is placed parallel to it and facing it, and an ND filter (230) is placed on the upper surface of the polarizing beam splitter (220). The polarizing beam splitter (220) reflects light (La) incident from a light source not shown toward the retroreflector (200), and the light (La') retroreflected from the retroreflector (200) passes through the polarizing beam splitter (220) and the ND filter (230) to form an aerial image. Meanwhile, unwanted light (Ld) that does not contribute to the formation of an image in the air (including light scattered from the retroreflective material (200) or light reflected from the surface of the λ / 4 plate (210)) is emitted to the outside by passing through the polarizing beam splitter (220) and the ND filter (230). Since the unwanted light (Ld) passes through the ND filter (230) only once, the amount of light reduced is relatively small.

[0027] In this embodiment, by attaching an ND filter (230) to the surface of the λ / 4 plate (210), the unwanted light (Le) that does not contribute to the formation of an image in the air from the light source passes through the ND filter (230) twice, so the amount of light reduced increases, and therefore the internal structure of the housing (110) is more suppressed from appearing bright, and thus the contrast in the air is improved. In this way, attaching the ND filter (230) to the surface side of the retroreflective material (200) causes the unwanted light to pass through the ND filter (230) twice, so the unwanted light can be reduced more compared to the conventional structure, leading to an improvement in the contrast in the air.

[0028] Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram showing the schematic configuration of a display device according to the second embodiment, and the same reference numerals are assigned to the same configuration as in the first embodiment. The display device (100A) of the second embodiment has a light source (120A) that outputs unpolarized light as a source image (P) of the air, a half mirror (300) used instead of the polarizing beam splitter (130) of the first embodiment, and an ND filter (310) attached to the surface of a retroreflective material (160) after removing the λ / 4 plate, and relates to an unpolarized optical system.

[0029] A half mirror (300) is an optical element that separates incident light into reflected light and transmitted light. Additionally, a polarizing plate (310) is an optical element that transmits light polarized in a specific direction. The half mirror (300) receives random light from a light source (120A) and reflects a portion of the incident light toward a retroreflective material (160). A portion of the light reflected from the half mirror (300) is incident on the retroreflective material (160) through the polarizing plate (310), and the light retroreflected thereon is incident on the half mirror (300) again through the polarizing plate (310), and the light (La') that passes through the half mirror (300) forms an aerial image (P).

[0030] Meanwhile, light (Lb) that does not contribute to the formation of an aerial image (P) output from a light source (120A) is, for example, not directly incident on a half mirror (300) but is incident on a retroreflective material (160) through a polarizing plate (310), and scattered light is generated therefrom. Since the amount of light (Lb) is reduced when passing through the polarizing plate (310), the scattered light (Lb') becomes weak light, and the internal structure of the optical system inside the housing is suppressed from appearing bright to the observer (U), thereby improving the contrast of the aerial image (P).

[0031] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. Explanation of the symbols

[0032] 100, 100A: Display device 110: Housing 120: Display 130: Polarizing beam splitter 140: ND filter 150: λ / 4th edition 160: Retroreflective 300: Half Mirror 310: Polarizer

Claims

Claim 1 A display device capable of displaying an aerial image using retroreflection, comprising a light source, a polarizing beam splitter disposed at a position where light from the light source is incident, a retroreflective material, a λ / 4 plate disposed on the surface of the retroreflective material, and a photosensitive filter disposed on the surface of the λ / 4 plate, wherein the retroreflective material receives light reflected from the polarizing beam splitter through the photosensitive filter and the λ / 4 plate, and the polarizing beam splitter transmits light retroreflected from the retroreflective material through the λ / 4 plate and the photosensitive filter to form the aerial image. Claim 2 In claim 1, the photosensitive filter is a display device that is an ND filter. Claim 3 A display device according to claim 1, wherein the λ / 4 plate and the photosensitive filter are laminated on the surface of the retroreflective material. Claim 4 In claim 1 or 3, the photosensitive filter is a display device attached to the upper or lower surface of the λ / 4 plate. Claim 5 A display device capable of displaying an aerial image using retroreflection, comprising a light source, a half mirror disposed at a position where light from the light source is incident, a retroreflective material, and a polarizing plate disposed on the surface of the retroreflective material, wherein the retroreflective material receives light reflected from the half mirror through the polarizing plate, and the half mirror transmits light retroreflected from the retroreflective material through the polarizing plate to form the aerial image.

Images