Display device

Abstract

A display device (2) is provided with: a transparent display (30) which has a display surface (38) for that displays an image on a front surface (30a) and which transmits background light; and a reflective polarizing plate (26) which is disposed so as to face the display surface (38) of the transparent display (30), the reflective polarizing plate (26) transmitting a part of display light representing an image emitted from the display surface (38) of the transparent display (30), and reflecting another part of the display light toward the transparent display (30).

Description

display device

[0001] The present disclosure relates to a display device having a transparent display.

[0002] Transparent displays that transmit background light are known. A display surface for displaying an image is formed on the front surface of the transparent display. However, due to the internal structure of the transparent display, it is not possible to extract the display light representing the image displayed on the display surface to the rear side of the transparent display, so it is not possible to display an image on the rear side of the transparent display.

[0003] In the field of display devices, there is a need to use the above-mentioned transparent display from the viewpoint of design and to display images on both the front and rear surfaces of the display device. As a display device that meets such needs, for example, a display device described in Patent Document 1 has been proposed.

[0004] The display device described in Patent Document 1 uses two transparent displays, i.e., a first transparent display and a second transparent display, and the back surfaces of the first transparent display and the second transparent display are attached back to back. Different images are displayed on the display surfaces of the first transparent display and the second transparent display.

[0005] International Publication No. 2023 / 181464

[0006] The present disclosure provides a display device that can display images on both the front and rear surfaces with a simple configuration.

[0007] The display device of the present disclosure comprises a transparent display having a display surface for displaying an image on the front side and transmitting background light, and an optical element arranged opposite the display surface of the transparent display, which transmits a portion of display light representing the image emitted from the display surface of the transparent display and reflects another portion of the display light toward the transparent display.

[0008] According to the display device of the present disclosure, it is possible to display images on both the front and rear surfaces with a simple configuration.

[0009] FIG. 1 is a perspective view showing the front side of a display device according to embodiment 1. FIG. 2 is a perspective view showing the rear side of a display device according to embodiment 1. FIG. 3 is a schematic cross-sectional view of the display device according to embodiment 1 taken along line III-III in FIG. 1. FIG. 4 is an exploded perspective view showing a transparent display panel unit of the display device according to embodiment 1. FIG. 5 is a schematic view for explaining the bidirectional viewing function of the display device according to embodiment 1. FIG. 6 is a schematic view for explaining the glare reduction function of the display device according to embodiment 1. FIG. 7 is a view for explaining an application example of the display device according to embodiment 1. FIG. 8 is a schematic cross-sectional view of a display device according to a modified example of embodiment 1. FIG. 9 is a schematic cross-sectional view of a display device according to embodiment 2. FIG. 10 is a schematic cross-sectional view of a display device according to embodiment 3.

[0010] (Findings that Form the Basis of the Present Disclosure) The present inventors have found that the following problems arise with the techniques described in the "Background Art" section.

[0011] The display device described in Patent Document 1 above requires two transparent displays, which makes the configuration of the control device for controlling the display content on each display surface of the two transparent displays complex, resulting in the problem that the configuration of the display device becomes large.

[0012] Therefore, after extensive research, the inventors have devised a display device that can display images on both the front and back surfaces with a simple configuration using a single transparent display.

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of well-known matters or redundant explanation of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following explanation and to facilitate understanding by those skilled in the art.

[0014] The inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0015] (Embodiment 1) [1-1. Configuration of Display Device] First, the configuration of a display device 2 according to embodiment 1 will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view showing the front side of the display device 2 according to embodiment 1. Fig. 2 is a perspective view showing the rear side of the display device 2 according to embodiment 1. Fig. 3 is a schematic cross-sectional view of the display device 2 according to embodiment 1 taken along line III-III in Fig. 1. Fig. 4 is an exploded perspective view showing a transparent display panel unit 10 of the display device 2 according to embodiment 1.

[0016] In each drawing, the left-right direction of the display device 2 is the X-axis direction, the front-rear direction of the display device 2 is the Y-axis direction, and the up-down direction of the display device 2 is the Z-axis direction. In this specification, "rear" means the positive side of the Y-axis, and "front" means the negative side of the Y-axis. In this specification, "up" means the positive side of the Z-axis, and "down" means the negative side of the Z-axis. In this specification, "front" means the surface on the negative side of the Y-axis, and "rear" means the surface on the positive side of the Y-axis.

[0017] As shown in FIGS. 1 and 2, the display device 2 includes a frame 4, a pair of legs 6 and 8, and a transparent display panel unit 10.

[0018] The frame body 4 is formed in a rectangular frame shape when viewed in the XZ plane, and is disposed so as to cover the outer periphery of the transparent display panel unit 10 .

[0019] The pair of legs 6, 8 are stands for supporting the frame body 4 and the transparent display panel unit 10 from below, and are placed on, for example, a table, a counter, or the floor. The pair of legs 6, 8 extend downward from both ends of the lower end of the frame body 4, respectively.

[0020] The transparent display panel unit 10 is formed in the shape of a rectangular panel when viewed in the XZ plane. The transparent display panel unit 10 is a transparent display panel unit that transmits background light and can display images (e.g., images 12 and 14) on both its front surface 10a and its back surface 10b opposite the front surface 10a. In this embodiment, the transmittance of the transparent display panel unit 10 is, for example, approximately 43%.

[0021] In this specification, the term "image" may refer to either a still image or a moving image, or may refer to video content including both still images and moving images. In addition, in this specification, the term "transparent" is a concept that includes not only complete transparency, which transmits all visible light, but also semi-transparency, which transmits part of visible light.

[0022] 1 , when viewed from a person standing on the front surface 10a side of the transparent display panel unit 10 (i.e., the front surface side of the display device 2), an object 16 standing on the back surface 10b side of the transparent display panel unit 10 (i.e., the back surface side of the display device 2) can be seen through the transparent display panel unit 10. That is, background light representing the object 16 standing behind the transparent display panel unit 10 can be seen through the transparent display panel unit 10.

[0023] 2 , an object 18 present on the front surface 10a of the transparent display panel unit 10 can be seen by a person present on the rear surface 10b of the transparent display panel unit 10, passing through the transparent display panel unit 10. That is, background light representing an object 18 present in the background of the transparent display panel unit 10 can be seen by passing through the transparent display panel unit 10.

[0024] As shown in FIGS. 1 and 2, an image 12 and an image 14 are displayed on the transparent display panel unit 10. As shown in FIG.

[0025] The image 12 is, for example, an image showing the character string "ABCD," and is an image presented to a person standing on the front surface 10a side of the transparent display panel unit 10. Therefore, as shown in Fig. 1, the image 12 is displayed in the correct orientation when viewed from a person standing on the front surface 10a side of the transparent display panel unit 10. On the other hand, as shown in Fig. 2, the image 12 is displayed in a mirror-inverted state when viewed from a person standing on the rear surface 10b side of the transparent display panel unit 10.

[0026] The image 14 is an image showing, for example, the character string "EFGH," and is an image presented to a person standing on the rear surface 10b side of the transparent display panel unit 10. Therefore, as shown in Fig. 2, the image 14 is displayed in the correct orientation when viewed from a person standing on the rear surface 10b side of the transparent display panel unit 10. On the other hand, as shown in Fig. 1, the image 14 is displayed in a mirror-inverted state when viewed from a person standing on the front surface 10a side of the transparent display panel unit 10.

[0027] 3 and 4, the transparent display panel unit 10 includes an anti-reflection film 20, a cover glass 22, an absorptive polarizing plate 24, a reflective polarizing plate 26 (an example of an optical member), a λ / 4 plate 28, and a transparent display 30. The anti-reflection film 20, the cover glass 22, the absorptive polarizing plate 24, the reflective polarizing plate 26, the λ / 4 plate 28, and the transparent display 30 are layered in this order from the front surface 10a side toward the rear surface 10b side of the transparent display panel unit 10. For convenience of explanation, the frame 4 and legs 8 are not shown in FIG. 3.

[0028] The anti-reflection film 20 is a transparent film that suppresses reflection of external light on the front surface of the cover glass 22, and is attached to the front surface of the cover glass 22. The anti-reflection film 20 also has the function of suppressing shattering of the cover glass 22.

[0029] The cover glass 22 is a colorless, transparent or colored, transparent glass plate that protects the transparent display 30 and keeps the transparent display 30 flat. Note that the cover glass 22 does not have the function of controlling the polarization state of light incident on the front or back surface of the cover glass 22.

[0030] The absorptive polarizer 24 is disposed opposite the back surface of the cover glass 22. That is, the absorptive polarizer 24 is disposed on the opposite side of the transparent display 30 with the reflective polarizer 26 in between. The absorptive polarizer 24 has a transmission axis 32 that is parallel to, for example, the Z-axis direction. As a result, of the light incident on the absorptive polarizer 24, the absorptive polarizer 24 transmits a first polarized component having a polarization direction parallel to the transmission axis 32, and absorbs a second polarized component having a polarization direction orthogonal to the polarization direction of the first polarized component. Note that the state of the light of the first polarized component that has passed through the absorptive polarizer 24 is linearly polarized light.

[0031] Here, the first polarization component refers to the vector component in the Z-axis direction when any light is vector-decomposed into the Z-axis direction and the X-axis direction, and the second polarization component refers to the vector component in the X-axis direction when any light is vector-decomposed into the Z-axis direction and the X-axis direction.

[0032] In this specification, "parallel" does not only mean completely parallel, but also means that when they are substantially parallel, there is an error of, for example, a few degrees. Furthermore, in this specification, "orthogonal" does not only mean completely orthogonal, but also means that when they are substantially orthogonal, there is an error of, for example, a few degrees.

[0033] The reflective polarizer 26 is disposed opposite the back surface of the absorptive polarizer 24. That is, the reflective polarizer 26 is disposed between the absorptive polarizer 24 and the λ / 4 plate 28. The reflective polarizer 26 has a transmission axis 34 parallel to, for example, the Z-axis direction. The transmission axis 34 of the reflective polarizer 26 is parallel to (in the same direction as) the transmission axis 32 of the absorptive polarizer 24. As a result, the reflective polarizer 26 transmits, of the light incident on the reflective polarizer 26, a first polarization component having a polarization direction parallel to the transmission axis 34, and reflects a second polarization component having a polarization direction orthogonal to the polarization direction of the first polarization component. Note that the first polarization component transmitted through the reflective polarizer 26 and the second polarization component reflected by the reflective polarizer 26 are linearly polarized light.

[0034] That is, the reflective polarizing plate 26 functions as a half mirror, and the transmittance and reflectance of the reflective polarizing plate 26 are both preferably 30 to 85%, more preferably 30 to 70%. When the transmittance is X% and the reflectance is Y%, the relationship Y≦100%−X holds. The distance between the reflective polarizing plate 26 and the display surface 38 (described below) of the transparent display 30 is preferably 5 mm or less.

[0035] The λ / 4 plate 28 is disposed opposite the rear surface of the reflective polarizer 26. That is, the λ / 4 plate 28 is disposed between the reflective polarizer 26 and the transparent display 30. The λ / 4 plate 28 is a retardation plate that converts linearly polarized light (the first polarized component or the second polarized component) incident on the λ / 4 plate 28 into circularly polarized light and converts circularly polarized light incident on the λ / 4 plate 28 into linearly polarized light. The angle between the slow axis 36 of the λ / 4 plate 28 and the transmission axis 34 of the reflective polarizer 26 is 45°. This allows the λ / 4 plate 28 to generate a phase difference of ¼ of the wavelength λ (i.e., a phase difference of 90°) between the orthogonal polarized components of the light incident on the λ / 4 plate 28. The thickness of the λ / 4 plate 28 (i.e., its size in the Y-axis direction) is, for example, 30 to 40 μm.

[0036] In this specification, the above-mentioned "the angle between the slow axis 36 and the transmission axis 34 is 45°" does not only mean that the angle is exactly 45°, but also means that the angle is substantially 45°, including an error of, for example, several degrees.

[0037] The transparent display 30 is a transparent display that transmits background light and is configured, for example, by a top-emission transparent OLED (organic light-emitting diode) panel. A display surface 38 for displaying an image (e.g., image 12 and image 14 shown in FIG. 1 ) is formed on a front surface 30 a of the transparent display 30. Display light representing the image displayed on the display surface 38 is extracted from the front surface 30 a side of the transparent display 30.

[0038] Furthermore, when the transparent display 30 is used alone, the internal structure of the transparent display 30 makes it impossible to extract display light representing an image displayed on the display surface 38 to the rear surface 30b (i.e., the surface opposite to the front surface 30a) of the transparent display 30, and therefore an image cannot be displayed on the rear surface 30b of the transparent display 30. However, in this embodiment, as described below, a portion of the display light extracted to the front surface 30a of the transparent display 30 is reflected by the reflective polarizing plate 26, thereby making it possible to display an image also on the rear surface 30b of the transparent display 30.

[0039] A portion of the display light representing an image displayed on the display surface 38 of the transparent display 30 is emitted from the display surface 38, passes through the reflective polarizing plate 26, and reaches the eyes of a person present on the front surface 10a side of the transparent display panel unit 10. This allows a person present on the front surface 10a side of the transparent display panel unit 10 to view the image displayed on the display surface 38 of the transparent display 30 on the front surface 10a of the transparent display panel unit 10 through the reflective polarizing plate 26.

[0040] Furthermore, another portion of the display light emitted from the display surface 38 of the transparent display 30 is reflected by the reflective polarizing plate 26 toward the transparent display 30, then passes through the transparent display 30, and reaches the eyes of a person present on the rear surface 10b side of the transparent display panel unit 10. This allows a person present on the rear surface 10b side of the transparent display panel unit 10 to view the image displayed on the display surface 38 of the transparent display 30 on the rear surface 10b of the transparent display panel unit 10 (i.e., the rear surface 30b of the transparent display 30) via reflection by the reflective polarizing plate 26. Note that, as described above, because the display light is reflected by the reflective polarizing plate 26, the display orientation of the image is reversed left and right between the front surface 10a and the rear surface 10b of the transparent display panel unit 10.

[0041] Below, we will explain the characteristic functions of the display device 2, namely, the function of displaying images on both the front surface 10a and the back surface 10b of the transparent display panel unit 10 (hereinafter referred to as the ``bidirectional viewing function''), and the function of reducing reflections of external light on the transparent display panel unit 10 (hereinafter referred to as the ``reflection reduction function'').

[0042] First, the bidirectional viewing function of the display device 2 will be described with reference to Fig. 5. Fig. 5 is a schematic diagram for explaining the bidirectional viewing function of the display device 2 according to embodiment 1. For convenience of explanation, the anti-reflection film 20 and the cover glass 22 are omitted from Fig. 5.

[0043] The display light emitted from the display surface 38 of the transparent display 30 is natural light containing light of all polarization directions. For convenience of explanation, Fig. 5 illustrates the polarization components contained in the display light as a first polarization component polarized in the Z-axis direction and a second polarization component polarized in the X-axis direction.

[0044] 5 , the display light emitted from the display surface 38 of the transparent display 30 passes through the λ / 4 plate 28 as it is and then enters the reflective polarizing plate 26. Of the display light that has entered the reflective polarizing plate 26, a first polarized component having a polarization direction parallel to the transmission axis 34 passes through the reflective polarizing plate 26, and a second polarized component having a polarization direction perpendicular to the transmission axis 34 is reflected by the reflective polarizing plate 26.

[0045] The first polarized light component that has passed through the reflective polarizer 26 is incident on the absorptive polarizer 24. At this time, the first polarized light component having a polarization direction parallel to the transmission axis 32 passes through the absorptive polarizer 24 and is extracted to the front surface 10a side of the transparent display panel unit 10. As a result, a person standing on the front surface 10a side of the transparent display panel unit 10 can view the image displayed on the display surface 38 of the transparent display 30 on the front surface 10a of the transparent display panel unit 10 through the reflective polarizer 26.

[0046] On the other hand, the linearly polarized light (second polarization component) reflected by the reflective polarizer 26 is incident on the λ / 4 plate 28 and converted into circularly polarized light. The circularly polarized light that exits the λ / 4 plate 28 passes through the transparent display 30 and is extracted to the rear surface 10b side of the transparent display panel unit 10. This allows a person on the rear surface 10b side of the transparent display panel unit 10 to view an image displayed on the display surface 38 of the transparent display 30 on the rear surface 10b of the transparent display panel unit 10 via reflection by the reflective polarizer 26.

[0047] In this manner, images can be displayed on both the front surface 10 a and the rear surface 10 b of the transparent display panel unit 10 .

[0048] Next, the glare reduction function of the display device 2 will be described with reference to Fig. 6. Fig. 6 is a schematic diagram for explaining the glare reduction function of the display device 2 according to embodiment 1. For convenience of explanation, the anti-reflection film 20 and the cover glass 22 are omitted from Fig. 6.

[0049] The external light incident on the front surface 10a of the transparent display panel unit 10 from outside the display device 2 is natural light containing light of all polarization directions. For convenience of explanation, Fig. 6 illustrates the polarization components contained in the external light as a first polarization component polarized in a direction parallel to the Z-axis direction and a second polarization component polarized in a direction parallel to the X-axis direction.

[0050] 6 , external light incident on the front surface 10 a of the transparent display panel unit 10 is incident on the absorptive polarizer 24. Of the external light incident on the absorptive polarizer 24, a first polarized component having a polarization direction parallel to the transmission axis 32 is transmitted through the absorptive polarizer 24, and a second polarized component having a polarization direction perpendicular to the transmission axis 32 is absorbed by the absorptive polarizer 24.

[0051] The first polarized light component that has passed through the absorptive polarizer 24 is incident on the reflective polarizer 26. At this time, the first polarized light component having a polarization direction parallel to the transmission axis 34 is transmitted through the reflective polarizer 26 and is incident on the λ / 4 plate 28. Here, by arranging the absorptive polarizer 24 opposite the front surface of the reflective polarizer 26, the second polarized light component contained in the external light is not reflected by the reflective polarizer 26 and extracted to the front surface 10a side of the transparent display panel unit 10. This makes it possible to prevent the front surface 10a of the transparent display panel unit 10 from appearing as a mirror due to reflection of external light when viewed from a person standing on the front surface 10a side of the transparent display panel unit 10.

[0052] Furthermore, the linearly polarized light (first polarization component) that passes through the reflective polarizer 26 and enters the λ / 4 plate 28 is converted into first circularly polarized light. A portion of the first circularly polarized light passes through the transparent display 30. Another portion of the first circularly polarized light is reflected by the transparent display 30, becomes second circularly polarized light having a polarization direction opposite to that of the first circularly polarized light, and enters the λ / 4 plate 28.

[0053] The second circularly polarized light incident on the λ / 4 plate 28 is converted into linearly polarized light (a second polarization component with a polarization direction parallel to the X-axis direction). The second polarization component exiting the λ / 4 plate 28 is reflected by the reflective polarizer 26. Thereafter, the linearly polarized light (second polarization component) and the second circularly polarized light are attenuated as they are repeatedly reflected between the transparent display 30 and the reflective polarizer 26. As a result, external light is not extracted to the front surface 10a of the transparent display panel unit 10 after being reflected by the transparent display 30, and reflection of external light on the display surface 38 of the transparent display 30 can be suppressed.

[0054] In this way, the external light incident on the front surface 10a of the transparent display panel unit 10 is extracted to the front surface 10a side of the transparent display panel unit 10, thereby reducing the glare of the external light.

[0055] [1-2. Application Examples of the Display Device] An application example of the display device 2 according to the first embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining an application example of the display device 2 according to the first embodiment.

[0056] 7A, the display device 2 is applied to a real-time automatic translation system, for example, when a customer 40 and a store clerk 42, who speak different native languages, converse in a store. In this real-time automatic translation system, for example, the customer 40 who is present on the front surface 10a side of the transparent display panel unit 10 speaks in English, and the store clerk 42 who is present on the rear surface 10b side of the transparent display panel unit 10 speaks in Japanese.

[0057] 7B, when a customer 40 speaks in English to a store clerk 42 through the transparent display panel unit 10, the English sentence spoken by the customer 40 (e.g., "Hello.") is displayed in the correct orientation as seen from the customer 40 on the transparent display panel unit 10 as an image 12. At the same time, the sentence automatically translated from the English spoken by the customer 40 into Japanese (e.g., "Hello.") is displayed in a left-right inverted manner as an image 14 on the transparent display panel unit 10 as seen from the customer 40.

[0058] As a result, as shown in Fig. 7(b), the customer 40 can see the English sentence he or she spoke in the image 12 displayed on the transparent display panel unit 10 while looking at the face of the store clerk 42 through the transparent display panel unit 10. Also, as shown in Fig. 7(c), the store clerk 42 can see the sentence that has been automatically translated from the English spoken by the customer 40 into Japanese in the image 14 displayed on the transparent display panel unit 10 while looking at the face of the customer 40 through the transparent display panel unit 10. For ease of explanation, the sentences shown in the images 12 and 14 are omitted from Figs. 7(b) and 7(c).

[0059] 7C, when the store clerk 42 speaks to the customer 40 in Japanese through the transparent display panel unit 10, the Japanese sentence spoken by the store clerk 42 (e.g., "Thank you") is displayed in the correct orientation as image 14 on the transparent display panel unit 10 as seen from the store clerk 42. At the same time, the sentence automatically translated from the Japanese spoken by the store clerk 42 into English (e.g., "Thank you") is displayed in a left-right inverted state as image 12 on the transparent display panel unit 10 as seen from the store clerk 42.

[0060] 7(c), the store clerk 42 can see the Japanese sentence he or she spoke in the image 14 displayed on the transparent display panel unit 10 while looking at the face of the customer 40 through the transparent display panel unit 10. Also, as shown in FIG. 7(b), the customer 40 can see the Japanese sentence spoken by the store clerk 42, which has been automatically translated into English, in the image 12 displayed on the transparent display panel unit 10 while looking at the face of the store clerk 42 through the transparent display panel unit 10.

[0061] [1-3. Effects] As described above, in the present embodiment, by using the reflective polarizing plate 26, part of the display light emitted from the display surface 38 of the transparent display 30 is transmitted through the reflective polarizing plate 26, and another part of the display light is reflected by the reflective polarizing plate 26 toward the transparent display 30. This makes it possible to display images on both the front surface 10a and the back surface 10b of the transparent display panel unit 10 (i.e., the front surface and the back surface of the display device 2) with a simple configuration using a single transparent display 30.

[0062] In addition, in this embodiment, by using an absorbing polarizing plate 24, it is possible to prevent the front surface 10a of the transparent display panel unit 10 from appearing like a mirror due to reflection of external light when viewed from a person on the front surface 10a side of the transparent display panel unit 10.

[0063] In addition, in this embodiment, by using the λ / 4 plate 28, external light is not extracted to the front surface 10a of the transparent display panel unit 10 after being reflected by the transparent display 30, and external light can be prevented from being reflected on the display surface 38 of the transparent display 30.

[0064] [1-4. Modification] The configuration of a display device 2A according to a modification of embodiment 1 will be described with reference to Fig. 8. Fig. 8 is a schematic cross-sectional view of the display device 2A according to a modification of embodiment 1. Fig. 8 is a schematic cross-sectional view of the display device 2A taken along a cutting line corresponding to line III-III in Fig. 1.

[0065] As shown in Fig. 8, in a display device 2A according to the modified example, the arrangement of the cover glass 22 in the transparent display panel unit 10A is different from that of the display device 2 shown in Fig. 3. Specifically, the cover glass 22 is arranged between the absorptive polarizer 24 and the reflective polarizer 26.

[0066] As described above, the cover glass 22 does not have the function of controlling the polarization state of light incident on the front or back surface of the cover glass 22. Furthermore, the arrangement order of the absorptive polarizer 24, the reflective polarizer 26, and the λ / 4 plate 28 is the same as that of the display device 2 shown in Fig. 3. Therefore, even with the configuration of the display device 2A according to the modified example, the same effect as that of the display device 2 shown in Fig. 3 can be obtained.

[0067] (Embodiment 2) [2-1. Configuration of Display Device] The configuration of a display device 2B according to embodiment 2 will be described with reference to Fig. 9. Fig. 9 is a schematic cross-sectional view of display device 2B according to embodiment 2. Fig. 9 is a schematic cross-sectional view of display device 2B taken along a cutting line corresponding to line III-III in Fig. 1. In this embodiment, the same components as those in embodiment 1 above are denoted by the same reference numerals, and their description will be omitted.

[0068] 9 , in a display device 2B according to embodiment 2, the configuration of a transparent display panel unit 10B is different from that of embodiment 1. Specifically, the transparent display panel unit 10B has an anti-reflection film 20, a cover glass 22, an absorptive polarizer 24, a reflective polarizer 26, and a transparent display 30, but does not have the λ / 4 plate 28 described in embodiment 1. The anti-reflection film 20, the cover glass 22, the absorptive polarizer 24, the reflective polarizer 26, and the transparent display 30 are layered in this order from the front surface 10a side toward the back surface 10b side of the transparent display panel unit 10B.

[0069] In the display device 2B according to the second embodiment, similarly to the first embodiment, a reflective polarizing plate 26 is used, so that part of the display light emitted from the display surface of the transparent display 30 passes through the reflective polarizing plate 26, and another part of the display light is reflected by the reflective polarizing plate 26 toward the transparent display 30. This makes it possible to display images on both the front surface 10a and the back surface 10b of the transparent display panel unit 10B with a simple configuration using a single transparent display 30.

[0070] Furthermore, as in the above-described first embodiment, by using the absorbing polarizing plate 24, it is possible to prevent the front surface 10a of the transparent display panel unit 10B from appearing as a mirror due to reflection of external light when viewed from a person standing on the front surface 10a side of the transparent display panel unit 10B.

[0071] Furthermore, by omitting the generally expensive λ / 4 plate 28, the manufacturing cost of the display device 2B can be reduced compared to the first embodiment.

[0072] [2-2. Modification] The configuration of a display device 2C according to a modification of embodiment 2 will be described with reference to Fig. 10. Fig. 10 is a schematic cross-sectional view of the display device 2C according to a modification of embodiment 2. Fig. 10 is a schematic cross-sectional view of the display device 2C taken along a cutting line corresponding to line III-III in Fig. 1.

[0073] As shown in Fig. 10, in a display device 2C according to a modified example, the arrangement of the cover glass 22 in the transparent display panel unit 10C is different from that of the display device 2B shown in Fig. 9. Specifically, the cover glass 22 is arranged between the absorptive polarizer 24 and the reflective polarizer 26.

[0074] As described above, the cover glass 22 does not have the function of controlling the polarization state of light incident on the front or back surface of the cover glass 22. Furthermore, the arrangement order of the absorptive polarizer 24 and the reflective polarizer 26 is the same as that of the display device 2B shown in Fig. 9. Therefore, even with the configuration of the display device 2C according to the modified example, the same effect as that of the display device 2B shown in Fig. 9 can be obtained.

[0075] (Embodiment 3) The configuration of a display device 2D according to embodiment 3 will be described with reference to Fig. 11. Fig. 11 is a schematic cross-sectional view of the display device 2D according to embodiment 3. Fig. 11 is a schematic cross-sectional view of the display device 2D taken along a cutting line corresponding to line III-III in Fig. 1. In this embodiment, the same components as those in embodiment 1 above are denoted by the same reference numerals, and their description will be omitted.

[0076] 11 , in a display device 2D according to embodiment 3, the configuration of a transparent display panel unit 10D is different from that of embodiment 1. Specifically, the transparent display panel unit 10D has an anti-reflection film 20, a cover glass 22, a reflective polarizing plate 26, and a transparent display 30, but does not have the absorptive polarizing plate 24 and the λ / 4 plate 28 described in embodiment 1. The anti-reflection film 20, the cover glass 22, the reflective polarizing plate 26, and the transparent display 30 are layered in this order from the front surface 10a side toward the back surface 10b side of the transparent display panel unit 10D.

[0077] In the configuration of the display device 2D according to the third embodiment, similarly to the first embodiment, by using the reflective polarizing plate 26, part of the display light emitted from the display surface of the transparent display 30 is transmitted through the reflective polarizing plate 26, and another part of the display light is reflected by the reflective polarizing plate 26 toward the transparent display 30. This makes it possible to display images on both the front surface 10 a and the back surface 10 b of the transparent display panel unit 10D with a simple configuration using a single transparent display 30.

[0078] In this embodiment, a reflective polarizing plate 26 is used as the optical sheet, but this is not limited to this. For example, a half mirror formed by vapor deposition sputtering of a metal layer may be used, or a nano-laminate film (for example, Picasus (registered trademark) manufactured by Toray Industries, Inc.) in which multiple transparent resin layers with different refractive indices are stacked may be used.

[0079] (Additional Notes) (Technology 1) A display device comprising: a transparent display having a display surface for displaying an image on the front side and transmitting background light; and an optical element arranged opposite the display surface of the transparent display, the optical element transmitting a portion of display light representing the image emitted from the display surface of the transparent display and reflecting another portion of the display light toward the transparent display.

[0080] According to Technology 1, the optical member is disposed opposite the display surface of the transparent display, so that part of the display light emitted from the display surface of the transparent display passes through the optical member, and another part of the display light is reflected by the optical member toward the transparent display. This makes it possible to display images on both the front and back surfaces of the display device with a simple configuration using a single transparent display.

[0081] (Technology 2) The display device according to Technology 1, wherein the transmittance and reflectance of the optical member are both 30 to 70%.

[0082] According to Technique 2, by setting the transmittance and reflectance of the optical member in the range of 30 to 70%, it is possible to improve the visibility of the images displayed on both the front and rear surfaces of the display device.

[0083] (Technology 3) The display device according to Technology 1 or 2, wherein the distance between the optical member and the transparent display is 5 mm or less.

[0084] According to the third technique, it is possible to suppress the occurrence of moire caused by interference between the pixels of the transparent display and the light and dark pattern consisting of light-emitting and non-light-emitting areas of the transparent display.

[0085] (Technology 4) The display device according to any one of Technologies 1 to 3, wherein the optical member is a reflective polarizing plate that transmits a first polarized component and reflects a second polarized component having a polarization direction perpendicular to the polarization direction of the first polarized component.

[0086] According to the fourth technique, the configuration of the optical member can be simplified.

[0087] (Technology 5) The display device according to Technology 4, further comprising an absorptive polarizer disposed on the opposite side of the transparent display with the optical member therebetween, the absorptive polarizer transmitting the first polarized light component and absorbing the second polarized light component.

[0088] According to Technology 5, by placing an absorptive polarizing plate on the opposite side of the transparent display with an optical member in between, it is possible to prevent the front surface of the display device from appearing as a mirror due to reflection of external light when viewed from a person in front of the display device.

[0089] (Technology 6) The display device according to Technology 5, further comprising a λ / 4 plate disposed between the optical member and the transparent display, wherein the angle formed between the slow axis of the λ / 4 plate and the transmission axis of the absorptive polarizer is 45°.

[0090] According to the sixth technique, by disposing a λ / 4 plate between the optical member and the transparent display, it is possible to suppress reflection of external light on the display surface of the transparent display.

[0091] (Other Embodiments) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

[0092] Therefore, other embodiments will be exemplified below.

[0093] In the above-described first embodiment and the modified example of the first embodiment, the transparent display panel unit 10 (10A) includes the anti-reflection film 20, the cover glass 22, the absorptive polarizer 24, the reflective polarizer 26, the λ / 4 plate 28, and the transparent display 30. However, the absorptive polarizer 24 may be omitted, or either or both of the anti-reflection film 20 and the cover glass 22 may be omitted. Note that, when the cover glass 22 is omitted and the transparent display panel unit 10 (10A) includes the anti-reflection film 20, the anti-reflection film 20 can suppress reflection of external light at any interface of the transparent display panel unit 10 (10A).

[0094] In the above-described second embodiment and the modified example thereof, the transparent display panel unit 10B (10C) includes the anti-reflection film 20, the cover glass 22, the absorptive polarizer 24, the reflective polarizer 26, and the transparent display 30. However, one or both of the anti-reflection film 20 and the cover glass 22 may be omitted. For example, in the transparent display panel unit 10C shown in FIG. 10 , the anti-reflection film 20 may be omitted, and the absorptive polarizer 24, the cover glass 22, the reflective polarizer 26, and the transparent display 30 may be stacked in this order from the front surface 10a side to the rear surface 10b side of the transparent display panel unit 10C. Note that, if the cover glass 22 is omitted and the transparent display panel unit 10B (10C) includes the anti-reflection film 20, the anti-reflection film 20 can suppress reflection of external light at any interface of the transparent display panel unit 10B (10C).

[0095] In addition, in each of the above embodiments, the transparent display 30 is configured as a transparent OLED panel, but this is not limited to this, and the transparent display 30 may be configured as any transparent self-luminous panel, such as a transparent micro LED panel.

[0096] As described above, the embodiments have been described as examples of the technology in the present disclosure, and for that purpose, the accompanying drawings and detailed description have been provided.

[0097] Therefore, the components shown in the accompanying drawings and detailed description may include not only essential components for solving the problem, but also components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that these non-essential components are shown in the accompanying drawings or detailed description should not be interpreted as immediately indicating that these non-essential components are essential.

[0098] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

[0099] The display device of the present disclosure is applicable as a display used in, for example, a real-time automatic translation system.

[0100] 2, 2A, 2B, 2C, 2D Display device 4 Frame 6, 8 Legs 10, 10A, 10B, 10C, 10D Transparent display panel unit 10a, 30a Front surface 10b, 30b Back surface 12, 14 Image 16, 18 Object 20 Anti-reflection film 22 Cover glass 24 Absorptive polarizer 26 Reflective polarizer 28 λ / 4 plate 30 Transparent display 32, 34 Transmission axis 36 Slow axis 38 Display surface 40 Customer 42 Store clerk

Claims

1. A transparent display having a display surface on the front for displaying images and that transmits background light, The transparent display comprises an optical member disposed opposite the display surface of the transparent display, which transmits a portion of the display light representing the image emitted from the display surface of the transparent display, and reflects the other portion of the display light toward the transparent display, The display light emitted from the display surface of the transparent display is natural light. Display device.

2. The transmittance and reflectance of the optical element are both 30-70%. The display device according to claim 1.

3. The distance between the optical element and the transparent display is 5 mm or less. The display device according to claim 1.

4. The optical element is a reflective polarizer that transmits a first polarization component and reflects a second polarization component in a polarization direction perpendicular to the polarization direction of the first polarization component. The display device according to any one of claims 1 to 3.

5. The display device further includes an absorbing polarizing plate positioned on the opposite side of the transparent display with the optical member in between, the absorbing polarizing plate which transmits the first polarization component and absorbs the second polarization component. The display device according to claim 4.

6. The display device further comprises a λ / 4 plate disposed between the optical element and the transparent display, The angle between the slow axis of the λ / 4 plate and the transmission axis of the absorbing polarizer is 45°. The display device according to claim 5.