Display device

Abstract

To provide a display device that makes a light source less visible while maintaining the brightness of an aerial image.SOLUTION: A display device 100 for an aerial image according to the present invention includes a light source 110 which is disposed to be inclined on one side of a reference line L, a retroreflective member 120 which is disposed to be inclined on the other side of the reference line L, a polarizing beam splitter 130 which is arranged to face the light source 110 and the retroreflective member 120, and a transmission film 140 which is formed on the polarizing beam splitter 130. The transmission film 140 includes a region 140A with low transmittance and a region 140B with high transmittance. The region 140A with low transmittance makes the light source 110 less visible within a range where the aerial image is visible.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a display device having a function of displaying an image in the air by utilizing retroreflection. [Background technology]

[0002] Aerial imaging by retroreflection (AIRR) is known. For example, Patent Document 1 discloses an aerial image display device that positions a light source and a retroreflection member so that light specularly reflected by the retroreflection member does not enter the observation range. Patent Document 2 discloses an aerial image display device that changes the tilt angle of the display light source and the tilt angle of the beam splitter to prevent the original image of the display light source from entering the aerial image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-150245 [Patent Document 2] Japanese Patent Publication No. 2022-180814 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the technologies used in AIRR display devices to create floating images is the use of a polarized beam splitter and a retroreflector. With this method, the original image is transmitted and reflected by the polarized beam splitter and the retroreflector, and then the floating image is formed at the end of the transmitted and reflected image. Therefore, depending on the angle from which the floating image is viewed, the original image (display light source or LED light source) can be seen by the viewer, which can make it difficult to decide whether to look at the floating image or the light source, creating a sense of discomfort.

[0005] Fig. 1(A) is a perspective view showing an example of a conventional aerial image display device. The aerial image display device 10 houses an optical system, such as a light source and a retroreflective member, inside a housing 20 with a polarizing beam splitter mounted on its surface, and displays an aerial image Q (numbers 1, 2, 3, 4, and 5) above the housing 20. However, depending on the angle from which the aerial image Q is viewed, the light source (original image P) inside the housing 20 becomes visible.

[0006] In Patent Document 2, the angle of the display light source is limited so that the viewer cannot see the original image, but this method has problems such as limiting the tilt of the aerial image and increasing the thickness of the product.

[0007] 1(B), a decorative sheet (transmitting film) 30 that can transmit light with a certain transmittance is formed on the surface of the housing 20, and conceals the interior of the housing 20 while projecting the aerial image Q. However, with this method, the decorative sheet 30 has the same transmittance, and if the transmittance of the decorative sheet 30 is low, the brightness of the aerial image Q decreases. Conversely, if the transmittance of the decorative sheet 30 is increased, the decrease in brightness of the aerial image Q can be suppressed, but there is a trade-off in that the concealment of the interior of the housing 20 decreases.

[0008] The present invention aims to solve such conventional problems and provide a display device that makes the light source less visible while maintaining the brightness of the aerial image. [Means for solving the problem]

[0009] The display device of the present invention is capable of displaying an aerial image using retroreflection, and comprises a light source arranged at an angle to one side of a reference line, a retroreflective member arranged at an angle to the other side of the reference line, a polarizing beam splitter arranged to face the light source and the retroreflective member, and a transmissive film formed on the polarizing beam splitter, the transmissive film having an area of ​​low transmittance that makes it difficult to see the light source within the range in which the aerial image is visible.

[0010] In one embodiment, the transmission film includes a region in which the transmittance gradually increases from the low transmittance region. In one embodiment, the low transmittance region is a region in which at least a portion of the aerial image is visible and the aerial image is not missing. In one embodiment, the low transmittance region is determined based on the position where a line connecting an edge of the aerial image and an edge of the light source intersects with the transmission film. In one embodiment, the reference line is orthogonal to a major surface of the polarizing beam splitter, an angle formed between the reference line and an optical axis orthogonal to the major surface of the light source is less than 90 degrees, and an angle formed between the reference line and an optical axis orthogonal to the major surface of the reflecting member is less than 90 degrees. [Effects of the Invention]

[0011] According to the present invention, by forming a transmission film on a polarizing beam splitter having an area of ​​low transmittance that makes the light source difficult to see in the range where the aerial image is visible, it is possible to make the light source difficult to see while maintaining the brightness of the aerial image. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an example of a conventional aerial image display device. [Figure 2] 2A and 2B are diagrams showing the configuration of an aerial image display device according to an embodiment of the present invention, in which FIG. 2A is a diagram showing a schematic cross section of each part constituting the display device, and FIG. 2B is a diagram explaining the relationship between the observation range of the aerial image in the display device of FIG. 2A and the area of ​​low transmittance of the transmission film. [Figure 3] 1 is a perspective view showing an example of the external configuration of an aerial image display device according to an embodiment of the present invention; [Figure 4] 10A and 10B are diagrams illustrating another example of the configuration of the transmission film according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The aerial image display device of the present invention does not restrict the position or angle of light sources such as displays or LEDs, but uses a transparent film (decorative sheet) to make the original image (light source) difficult to see within the range where the aerial image is visible, while minimizing the reduction in brightness of the aerial image. [Example]

[0014] Next, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings include exaggerated representations to facilitate understanding of the invention, and do not directly represent the shape and scale of the actual product.

[0015] FIG. 2(A) is a diagram showing a schematic cross section of each part constituting a display device according to an embodiment of the present invention, and FIG. 2(B) is a diagram explaining the relationship between the observation range of an aerial image in the display device of FIG. 2(A) and the area of ​​low transmittance of the transmission film.

[0016] The aerial image display device 100 of this embodiment is configured to include a light source 110, a retroreflective member 120, a polarizing beam splitter 130, and a transmissive film (decorative sheet) 140. Although these members are not shown here, they can be attached to, for example, a case or a housing.

[0017] The light source 110 is not particularly limited as long as it has the function of emitting a video or image, and may be, for example, a display light source such as a liquid crystal display device, an organic EL display device, or a projection display device, or an LED light source. A display light source has, for example, a rectangular emission surface and emits an image in the normal direction (optical axis direction) of the emission surface. A display light source may be, for example, the screen of a mobile terminal such as a smartphone, or the screen of a personal computer or a projector. An LED light source includes, for example, multiple LEDs (light-emitting elements) and emits a video or image by emitting light from the LEDs.

[0018] The light source 110 illustrated here has a generally rectangular shape and is disposed so as to be tilted at a certain angle with respect to a reference line L that is perpendicular to the main surface of the polarizing beam splitter 130. One end E of the light source 110 is close to the reference line L and is tilted so as to face the direction of the polarizing beam splitter 130.

[0019] The retroreflective member 120 is an optical member that reflects light in the same direction as the incident light, and is composed of, for example, prism-type retroreflective elements such as triangular pyramid-type retroreflective elements and full cube-corner-type retroreflective elements, or bead-type retroreflective elements. For example, if the light emitted from the light source 110 is polarized light, a phase difference film (e.g., a λ / 4 film) is formed on the surface of the retroreflective member 120.

[0020] The retroreflective member 120 is, for example, in the form of a sheet or thin plate having a generally rectangular shape, and one end F thereof is located below end E of the light source 110 and close to the reference line L, and is arranged at a certain angle so as to face the direction of the polarizing beam splitter 130. In other words, the light source 110 is arranged on one side of the reference line L, and the retroreflective member 120 is arranged on the other side, the angle formed between the reference line L and the optical axis perpendicular to the principal surface of the light source 110 is less than 90 degrees, and the angle formed between the reference line L and the optical axis perpendicular to the principal surface of the retroreflective member 120 is less than 90 degrees, and the two are arranged in a generally inverted V shape.

[0021] The polarizing beam splitter 130 is an optical element that separates incident light into transmitted light and reflected light, and is capable of reflecting light of a specific polarization direction and transmitting light of other polarization directions. The polarizing beam splitter 130 is, for example, configured as a roughly rectangular sheet or thin plate, and is disposed so that its main surface is perpendicular to the reference line L, and is disposed above the light source 110 and the retroreflective member 120 so as to face them. The polarizing beam splitter 130, for example, reflects light of a certain polarization direction emitted from the light source 110 toward the retroreflective member 120, and transmits light of a certain polarization direction retroreflected from the retroreflective member 120.

[0022] The transmission film 140 has, for example, a rectangular shape and is formed on the polarizing beam splitter 130. The transmission film 140 is either the same size as the polarizing beam splitter 130 or large enough to cover most of the polarizing beam splitter 130. A distinctive feature of this embodiment is that the transmission film 140 does not have a uniform transmittance as a whole, but rather has a partially changed transmittance, thereby making it difficult to see the light source 110 (original image) within the range where the aerial image is visible, while suppressing a decrease in the luminance of the aerial image.

[0023] The transmission film 140 illustrated in FIG. 2(A) is configured so that the transmittance is low in a region 140A to the left of a boundary B near a reference line L, and high in a region 140B to the right of the boundary B. The transmission film 140 may be configured from a single film, or may be configured from a laminate of multiple films. The transmission film 140 may be configured, for example, by attaching an ND filter (neutral density filter) to polycarbonate (PC) having a uniform transmittance to form the region 140A with low transmittance, or may be configured from a single layer of polycarbonate or an ND filter including a region with low transmittance and a region with high transmittance.

[0024] Light emitted from the light source 110 is reflected by the polarizing beam splitter 130, and the reflected light is incident on the opposing retroreflective member 120. The retroreflective member 120 reflects the light in the same direction as the incident direction, and the reflected light passes through the polarizing beam splitter 130 and the transmission film 140, where the transmitted light forms an image. As a result, an aerial image Q is generated, as shown in FIG. 2(B). The aerial image Q is generated at a position symmetrical to the light source 110 (original image P) with respect to the main surface of the polarizing beam splitter 130.

[0025] The range H in which the aerial image Q can be seen is limited to the range in which the retroreflective member 120 can be seen from the observer's viewpoint via the polarizing beam splitter 130. Viewpoint U2 represents the eye position when the aerial image Q is viewed from the front, viewpoint U1 represents the leftmost eye position from which the entire aerial image Q can be seen, and viewpoint U3 represents the rightmost eye position from which the entire aerial image Q can be seen. If the eye position moves further left than viewpoint U1 or further right than viewpoint U3, the retroreflective member 120 cannot be seen completely in the direction of the aerial image Q, and therefore the entire aerial image Q cannot be seen. In other words, range H shown in FIG. 2(B) represents the range in which at least a portion of the aerial image Q can be seen.

[0026] The region 140A of low transmittance of the transmission film 140 is formed in a range H where at least a part of the aerial image Q is visible so that the aerial image is not lost. That is, the range where the transmittance is low is the region to the left of the point (boundary B) where the dash-dotted line H1 connecting the right end of the aerial image Q and the right end of the light source 110 intersects with the transmission film 140. The range where the transmittance is high is the other region to the right of the boundary B.

[0027] When the aerial image Q is viewed from viewpoint U3, the light source 110 (original image P) is present in the line of sight. Therefore, if the transmittance of the transmissive film 140 is high, the light source 110, i.e., the original image P, will be visible, reducing the visibility of the aerial image Q. For this reason, in this embodiment, a low-transmittance region 140A is provided in the transmissive film 140 to attenuate the transmission of the light source 110 in the line of sight of viewpoint U3, making the light source 110 less visible and improving the visibility of the aerial image Q. However, if the transmittance of the low-transmittance region 140A is reduced more than necessary, the luminance of the aerial image Q will also be reduced. Therefore, the transmittance of the low-transmittance region 140A is set to a level that does not affect the visibility of the aerial image Q.

[0028] When the aerial image Q is viewed from viewpoints U1 and U2, the light source 110 is not present in the line of sight, but the high transmittance region 140B is present in the line of sight, thereby suppressing a decrease in the luminance of the aerial image Q. Note that if the transmission film 140 only has the low transmittance region 140A (i.e., does not have the high transmittance region 140B), the change in luminance of the aerial image Q will be significantly large. Therefore, in this embodiment, the transmission film 140 has the low transmittance region 140A and the high transmittance region 140B.

[0029] 3 is a perspective view showing an example of the external configuration of an aerial image display device 100 of this embodiment. As shown in the figure, the display device 100 includes a housing 150, inside which a light source 110 and a retroreflective member 120 are disposed, and a laminate of a polarizing beam splitter 130 and a transmissive film 140 is attached to the surface of the housing 150. The transmissive film 140 includes, at a boundary B, a region 140A with low transmittance and a region 140B with high transmittance.

[0030] In the conventional display device 10A shown in Figure 1(B), the light source (original image P) inside the housing 10 is visible depending on the direction from which the user views, making it difficult to see the aerial image Q. However, in this embodiment, the low transmittance area 140A makes it difficult to see the light source (original image P) inside the housing 150, thereby improving the visibility of the aerial image Q.

[0031] In the above embodiment, the transmittance of the transmission film is changed at boundary B, but if the change in transmittance becomes rapid, the change in luminance of the aerial image Q also becomes large. For this reason, as shown in Figures 4(A) to 4(C), the transmittance of the transmission film may be gradually changed linearly from boundary B to a predetermined point B1, or may be changed in steps, or may be changed so as to gradually increase in a curve, thereby reducing or mitigating the change in luminance of the aerial image Q.

[0032] 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]

[0033] 100:Display device 110: Light source 120: Retroreflective material 130: Polarizing beam splitter 140:Transparent film (decorative sheet) 140A: Low transmittance area 140B: High transmittance area 150: Cabinet

Claims

1. A display device capable of displaying an aerial image using retroreflection, a light source disposed at an angle to one side of a reference line; A retroreflective member disposed at an angle to the other side of the reference line; a polarizing beam splitter arranged to face the light source and the retroreflective member; a transmission film formed on the polarizing beam splitter, The display device, wherein the transmission film has an area of ​​low transmittance that makes it difficult to see the light source within the range in which the aerial image is visible.

2. The display device according to claim 1 , wherein the transmission film includes a region in which the transmittance gradually increases from the region in which the transmittance is low.

3. The display device according to claim 1 , wherein the region of low transmittance is a region in which at least a part of the aerial image is visible and the aerial image is not lost.

4. The display device according to claim 3 , wherein the region of low transmittance is determined based on a position where a line connecting an end of the aerial image and an end of the light source intersects with the transmission film.

5. 2. The display device according to claim 1, wherein the reference line is perpendicular to a main surface of the polarizing beam splitter, an angle formed between the reference line and an optical axis perpendicular to the main surface of the light source is less than 90 degrees, and an angle formed between the reference line and an optical axis perpendicular to the main surface of the reflecting member is less than 90 degrees.

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