Display device

Abstract

To provide a display device that improves the visibility and contrast of an aerial image.SOLUTION: An aerial image display device 100 according to the present invention includes: a light source 110 such as a display; a beam splitter 120 which separates incident light into transmission light and reflection light at a fixed ratio; and a retroreflective member 130 which has a chevron shape. An aerial image 140 is displayed with light La retroreflected by the retroreflective member 130. On the other hand, the specularly reflected light Lb is directed in the direction away from the aerial image 140. As a result, such a situation that a user observes a pseudo aerial image by the specularly reflected light Lb is suppressed and the visibility and contrast of the aerial image 140 are improved.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a display device that displays an image in the air using retroreflection. [Background technology]

[0002] Aerial imaging by retroreflection (AIRR) is known. For example, Patent Document 1 discloses a display device using two retroreflection members so that an image formed in the air can be observed from a wider angle. Patent Document 2 discloses a display device that suppresses deterioration of contrast and visibility by positioning a light source and a retroreflection member so that light regularly reflected by the retroreflection member does not enter the observation range. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-107165 A [Patent Document 2] Patent Publication No. 2022-150245 Summary of the Invention [Problem to be solved by the invention]

[0004] Fig. 1 is a schematic cross-sectional view showing the configuration of a conventional aerial image display device. The aerial image display device 10 includes a light source (e.g., a display that outputs an image) 20, a beam splitter 30 that separates incident light into reflected light and transmitted light at a predetermined ratio, and a retroreflective member 40.

[0005] The image emitted from the light source 20 is reflected by the beam splitter 30, and the reflected light travels to the retroreflective member 40. The retroreflective member 40 is an optical member that reflects light in the same direction as the incident light, and is composed of, for example, a corner cube type retroreflective element, a triangular pyramid type retroreflective element, a bead type retroreflective element, or the like. The light reflected by the retroreflective member 40 travels again to the beam splitter 30, and the light that passes through the beam splitter 30 is converged and then diffused again, and is imaged as an aerial image 50 in front of the observer's eyes. The aerial image 50 is formed at a position symmetrical to the light source 20 with respect to the surface of the beam splitter 30. The aerial image 50 that the user can observe is limited to the range where the retroreflective member 40 can be seen through the beam splitter 30 from the user's viewpoint.

[0006] Fig. 2(A) is a top view of a corner cube type retroreflective member, Fig. 2(B) is a top view showing one corner cube, and Fig. 2(C) is a schematic cross-sectional view of the retroreflective member. As shown in Fig. 2(B), one corner cube has a concave shape formed by joining the right-angled vertices of three right-angled isosceles triangles (the right-angled vertices are at the deepest part). Incident light Lin is reflected three times by each face of the corner cube, and the reflected light Lout is emitted in the same direction as the incident light Lin. At this time, an optical path difference D occurs between the incident light Lin and the reflected light Lout.

[0007] 3(A) is a cross-sectional view showing a specific example of the configuration of a retroreflective member. The retroreflective member 40 includes a patterned portion 42 made of a light-transmitting material, a reflective layer 44 (e.g., Al) formed on the inclined surface of the patterned portion 42, an adhesive 46 applied to the upper surface of the patterned portion 42, and a phase plate (e.g., a λ / 4 plate) 48 formed on the adhesive 46. The reflective layer 44 functions as a reflective layer, and the thickness including the adhesive 46 and the phase plate 48 is approximately 1 mm or less.

[0008] The light incident on the retroreflective member 40 is reflected multiple times by the reflective layer 44, and as shown in Fig. 3(B), the reflected light Lout is emitted in the same direction as the incident light Lin. The reflected light La retroreflected according to the optical characteristics of the retroreflective member 40 is the intended light (or desired light).

[0009] On the other hand, a part of the light incident on the retroreflective member 40 is reflected, for example, by the surface of the phase plate 48 (reflected light L1). Such reflected light L1 is specular light reflected with a relationship of incident angle θ=reflection angle θ as shown in Fig. 3(C), and this is light that does not depend on the optical properties of the retroreflective member 40, that is, unintended light Lb.

[0010] 4 is a diagram illustrating the problems with the conventional aerial image display device. As described above, when unintended reflected light Lb occurs due to specular reflection by the retroreflective member 40, a pseudo aerial image is generated due to the specular reflection Lb, and the pseudo aerial image is reflected within the range where the user observes the aerial image 60, reducing the visibility and contrast of the aerial image 60.

[0011] An object of the present invention is to solve such conventional problems and to provide a display device with improved visibility and contrast of aerial images. [Means for solving the problem]

[0012] The display device of the present invention is capable of displaying an aerial image by utilizing retroreflection, and includes a light source that outputs the image, an optical element that separates incident light into reflected light and transmitted light at a certain ratio, and a retroreflective element that reflects the light incident from the optical element, wherein light representing the image is incident on the retroreflective element via the optical element, and the aerial image is displayed by the light reflected by the retroreflective element, and the retroreflective element is inclined so that light resulting from direct reflection of a portion of the light incident from the optical element is directed away from the aerial image.

[0013] In one embodiment, the retroreflective member includes a first reflective surface and a second reflective surface that intersects with the first reflective surface at a certain angle. In one embodiment, the retroreflective member is inclined with respect to the main surface of the optical component. In one embodiment, the retroreflective member is inclined so that light resulting from specular reflection of a portion of the light incident on the optical component is outside the user's field of view. Effect of the Invention

[0014] According to the present invention, the retroreflective member is inclined so that a portion of the light incident from the optical member is reflected specularly away from the aerial image, thereby preventing the user from observing a pseudo aerial image caused by specular reflection within the range in which the aerial image is observed, thereby improving the visibility and contrast of the aerial image. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a conventional aerial image display device that uses retroreflection. [Diagram 2] 1A and 1B are diagrams illustrating the optical properties of a corner cube type retroreflective member. [Diagram 3] Figure 3(A) is a cross-sectional view showing an example of the configuration of a retroreflective member, Figure 3(B) is a schematic diagram showing the relationship between incident light and reflected light in a mirror, etc., and Figure 3(C) is a schematic diagram showing the relationship between incident light and reflected light in a retroreflective plate. [Figure 4] 1A and 1B are diagrams illustrating problems with a conventional aerial image display device. [Diagram 5] 1 is a perspective view showing a schematic configuration of an aerial image display device according to a first embodiment of the present invention. [Figure 6] FIG. 1 is a diagram showing a schematic diagram of the relationship between each part of a conventional aerial image display device and an optical path. [Figure 7] 1 is a diagram showing a schematic diagram of the relationship between each part and an optical path of an aerial image display device according to a first embodiment of the present invention. [Figure 8] 8(A) is a cross-sectional view taken along line YY in FIG. 7(C), and FIG. 8(B) is a cross-sectional view taken along line Y1-Y1 in FIG. 10(C). [Figure 9] FIG. 13 is a diagram showing a modified example of the first embodiment. [Figure 10] 10 is a diagram showing a schematic diagram of the relationship between each part and an optical path of an aerial image display device according to a second embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The display device according to the present invention displays an image in the air by the AIRR method. The display device according to the present invention can be applied to a user input interface using an aerial image. It should be noted that the drawings referred to in the following description of the embodiments include exaggerated representations to facilitate understanding of the invention, and do not directly represent the shape and scale of the actual product. EXAMPLES

[0017] Next, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 5 is a perspective view showing the configuration of an aerial image display device according to a first embodiment of the present invention. As shown in the figure, the aerial image display device 100 of this embodiment is configured to include a light source 110 such as a display that displays an image, a beam splitter (or half mirror) 120 that separates incident light into transmitted light and reflected light at a certain ratio, and a mountain-shaped retroreflective member 130, and displays an aerial image 140 of an image output to the light source 110 by the AIRR method.

[0018] A characteristic feature of this embodiment is that the retroreflective member 130 does not provide a flat surface but has a mountain-like shape, thereby preventing unintended reflected light Lb generated by the retroreflective member 130 from entering the field of view of the aerial image 140 as much as possible.

[0019] Fig. 6 is a perspective view, a front view, a top view, and a side view showing the relationship between each part of the conventional aerial image display device shown in Fig. 4 and the incident light / reflected light, Fig. 7 is a perspective view, a front view, a top view, and a side view showing the relationship between each part of the aerial image display device of the first embodiment and the incident light / reflected light, and Fig. 8(A) is a cross-sectional view taken along line YY in Fig. 7(C). The operation of the aerial image display device of this embodiment will be described with reference to these figures.

[0020] As shown in Fig. 6, in a conventional aerial image display device 10, a light source 20 and a retroreflective member 40 are disposed below a beam splitter 30. The retroreflective member 40 has a substantially flat main surface, and an aerial image 50 is displayed by light La that is reflected in the same direction as the incident light. Meanwhile, light Lb specularly reflected by the retroreflective member 40 travels in the direction of the aerial image 50 because the main surface of the retroreflective member 40 is flat. If the specularly reflected light Lb enters the range (field of view) where the user can observe the aerial image 50, a pseudo aerial image will be seen.

[0021] In contrast, in the aerial image display device 100 of this embodiment, the retroreflective member 130 has a mountain-shaped reflective surface as shown in Fig. 7. Except for the configuration of the retroreflective member 130, the other configurations are the same as those of the conventional aerial image display device 10.

[0022] Here, the beam splitter 120 is disposed with its main surface parallel to the XY plane. As shown in Fig. 7(C), the beam splitter 120 is rectangular in the XY plane, and has a first side 120X in the X direction and a second side 120Y in the Y direction. In addition, when the normal direction of the light source 110, for example, the display surface of a display, is taken as the optical axis, the direction of the optical axis projected onto the XY plane is the X direction, which is parallel to the first side 120X.

[0023] In one embodiment, the retroreflective member 130 has a first reflecting surface 130A having a generally flat rectangular shape, a second reflecting surface 130B having a generally flat rectangular shape, and an apex 130C where the first reflecting surface 130A and the second reflecting surface 130B intersect. The first reflecting surface 130A and the second reflecting surface 130 may be formed by folding one retroreflective member, or may be formed by bonding two retroreflective members with an adhesive or the like. In addition, the first reflecting surface 130A and the second reflecting surface 130B may be configured to be symmetrical with respect to the apex 130C, or may be configured to be asymmetrical, for example.

[0024] Retroreflective member 130 is disposed so that the direction of top edge 130C projected onto the XY plane is the X direction, i.e., parallel to the optical axis in the XY plane, and top edge 130C is inclined in the Z direction with respect to the main surface of beam splitter 120. As a result, as shown in the YY line cross section of FIG. 8(A), first reflecting surface 130A and second reflecting surface 130B are inclined from top edge 130C toward the side so as to move away from the main surface of beam splitter 120. In addition, intersection angle α between first reflecting surface 130A and second reflecting surface 130B is set so that all or a part of specularly reflected light Lb is directed in a direction outside the range in which the user can observe aerial image 140.

[0025] When light source 110 outputs an image, light representing the image is emitted in the optical axis direction, and the light is reflected by beam splitter 120 and retroreflective member 130, and then passes through beam splitter 120 to display aerial image 140. Retroreflective member 130 has reflective surfaces 130A and 130B folded in a mountain shape, and due to its optical properties, the reflected light is emitted in the same direction as the incident light. In other words, reflected light La retroreflected by retroreflective member 130, i.e., intended reflected light La, generates aerial image 140 in the same manner as retroreflective member 40 of the conventional aerial image display device 10 shown in FIG. 6.

[0026] On the other hand, a part of the light incident from beam splitter 120 is specularly reflected by retroreflective member 130, but since first and second reflecting surfaces 130A, 130B are inclined from top edge 130C toward the side, the angle of incidence of the light incident on first and second reflecting surfaces 130A, 130B is larger than when first and second reflecting surfaces 130A, 130B are not inclined toward the side. Therefore, the reflection angle of reflected light Lb due to specular reflection at first and second reflecting surfaces 130A, 130B becomes larger, and unintended light Lb due to specular reflection is directed in a direction away from aerial image 140. As a result, it becomes difficult to observe a pseudo aerial image due to specular reflection within the range where the user observes aerial image 140, and the visibility and contrast of aerial image 140 can be improved.

[0027] In the above embodiment, the direction of apex 130C projected onto the XY plane is the X direction, that is, the same direction as the optical axis of light source 110, but retroreflective member 130 may be rotated, for example, by 90 degrees in the horizontal direction. In this case, in aerial image display device 100A shown in Fig. 9, the direction when apex 130C is projected onto the XY plane is the Y direction, which is perpendicular to the optical axis of light source 110. Even in such a configuration, light Lb specularly reflected by retroreflective member 130 is directed in a direction away from aerial image 140, making it difficult for the user to observe the pseudo aerial image.

[0028] Next, a second embodiment of the present invention will be described. Fig. 10 is a diagram showing the configuration of an aerial image display device 100B according to the second embodiment, and the same components as those in the first embodiment shown in Fig. 7 are given the same reference numerals.

[0029] In the second embodiment, the retroreflective member 150 provides a generally flat main surface, but as shown in the Y1-Y1 line cross section of FIG. 8(B), the retroreflective member 150 is inclined at an angle α with respect to the main surface of the beam splitter 120. The direction of the inclination may be opposite. In other words, the retroreflective member 150 corresponds to either the first reflecting surface 130A or the second reflecting surface 130B in the first embodiment. The angle α is set so that when a portion of the light incident from the beam splitter 120 is specularly reflected by the retroreflective member 150, the specularly reflected light Lb is directed in a direction away from the field of view of the aerial image 140. This improves the visibility and contrast of the aerial image 140.

[0030] Thus, according to this embodiment, the light reflected specularly by the retroreflective member is directed away from the aerial image, thereby preventing the user from observing a pseudo aerial image caused by specular reflection within the range in which the user observes the aerial image, thereby improving the visibility and contrast of the aerial image.

[0031] The shapes and sizes of the beam splitter and retroreflective member shown in the above examples are merely examples, and other shapes and sizes may be used. In addition, the retroreflective member has been shown to have a mountain-shaped configuration having first and second reflecting surfaces, but may be configured to have three or more reflecting surfaces, such as a triangular pyramid or a square pyramid. Furthermore, the angle of the mountain-shaped shape of the retroreflective member and the inclination angle α of the retroreflective member are appropriately selected in the optical design of the aerial image.

[0032] The aerial image display device of this embodiment can be applied to user interfaces. For example, the aerial image can be applied to computer devices, in-vehicle electronic devices, ATMs at banks, ticket vending machines at stations, elevator input buttons, etc.

[0033] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention described in the claims. [Explanation of symbols]

[0034] 100, 100A, 100B: Aerial image display device 110: Light source 120: Beam splitter 130, 150: Retroreflective material 130A: First reflecting surface 130B: Second reflective surface 130C: Top 140: Aerial footage

Claims

1. A display device capable of displaying an aerial image using retroreflection, A light source that outputs an image; an optical member that separates incident light into reflected light and transmitted light at a constant ratio; A retroreflective member that reflects light incident from the optical member, Light representing the image is incident on the retroreflective member via the optical member, and the aerial image is displayed by the light reflected by the retroreflective member. A display device in which the retroreflective member is inclined so that light resulting from specular reflection of a portion of the light incident on the optical member is directed in a direction away from the aerial image.

2. The display device according to claim 1 , wherein the retroreflective member includes a first reflective surface and a second reflective surface intersecting the first reflective surface at a certain angle.

3. The display device according to claim 1 , wherein the retroreflective member is inclined with respect to a main surface of the optical component.

4. The display device according to claim 1 , wherein the retroreflective member is inclined so that light resulting from specular reflection of a portion of the light incident on the optical member falls outside the user's field of view.

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