Transparent display device

Abstract

A transparent display device includes a transparent display panel and a first protective plate. The transparent display panel comprises a plurality of pixels. The pixels have a spacing P1 in a first direction and a spacing P2 in a second direction. Each pixel includes a light-emitting element. The first protective plate is located on a first surface of the transparent display panel. The top surface of the light-emitting element is spaced apart from the top surface of the first protective plate by a distance T1. By adjusting the spacing P1, spacing P2, and distance T1, the back-side light leakage problem of the transparent display device can be improved.

Description

Technical Field

[0001] This invention relates to a transparent display device. Prior Technology

[0002] Transparent displays are an advanced display technology that allows users to see the environment behind the screen while displaying content. They are lightweight, energy-efficient, and offer high image quality without obstructing the view.

[0003] Transparent displays have applications across multiple industries. In retail, they are commonly used for interactive window displays or product showcases, often combined with digital information overlay. In the automotive and aviation sectors, transparent displays serve as head-up displays on windshields, providing real-time navigation and safety data. Furthermore, transparent displays are being used in smart homes, museums, medical devices, and wearable technologies, offering innovative solutions for information presentation while seamlessly integrating with the surrounding environment. Summary of the Invention

[0004] This invention provides a transparent display device that can improve the problem of light leakage from the back side.

[0005] At least one embodiment of the present invention provides a transparent display device, including a transparent display panel and a first protective plate. The transparent display panel has a first surface and a second surface opposite to the first surface. The transparent display panel includes a plurality of pixels arranged in an array along a first direction and a second direction. The pixels have a spacing P1 in the first direction. The pixels have a spacing P2 in the second direction. Each pixel includes at least one light-emitting element. The first protective plate is located on the first surface of the transparent display panel. The first protective plate is located above the light-emitting elements, and the light-emitting elements are separated from the top surface of the first protective plate by a distance T1. The spacing P1, spacing P2, distance T1, and the refractive index n of the first protective plate conform to the conditions in Table 1.

[0006] At least one embodiment of the present invention provides a transparent display device, including a transparent display panel and a first protective plate. The transparent display panel has a first surface and a second surface opposite to the first surface. The transparent display panel includes a plurality of pixels, and the pixels have a pixel pitch in a first direction. Each pixel includes at least one light-emitting element. The first protective plate is located on the first surface of the transparent display panel. The light-emitting element is spaced apart from the top surface of the first protective plate by a distance T1. The protective plate has a refractive index n. The transparent display device conforms to the following (Mathematical Formula 1), (Mathematical Formula 2), and (Mathematical Formula 3), where ma is an integer less than 5: = (Mathematical formula 1); - 20˚= (Mathematical formula 2); (Mathematical formula 3) Simple Explanation of the Diagram

[0007] Figure 1A is a cross-sectional schematic diagram of a transparent display device 10 according to an embodiment of the present invention. Figure 1B is a partially enlarged cross-sectional view of the transparent display device in Figure 1A. Figure 1C is a top view of the transparent display device in Figure 1A. Figure 1D shows the brightness distribution of back-side light leakage of the transparent display device in Figure 1A from various viewing angles. Figures 2A to 2H show simulation data graphs illustrating the relationship between the difference between the incident angle θbm corresponding to the dark pattern of the transparent display device in some embodiments and the critical angle θC2 of the second protective plate, and mmax. Figures 3A, 4A and 5A are schematic cross-sectional views of a single-sided transparent display device according to some embodiments of the present invention. Figures 3B, 4B, and 5B show the irradiance distribution of back-side light leakage of the single-sided transparent display device in Figures 3A, 4A, and 5A at various viewing angles. Figure 6 is a light path diagram of the light emitted by one pixel of a single-sided transparent display device according to an embodiment of the present invention. Figures 7A, 7B, 8A, 8B, 9A, and 9B are data diagrams of the light leakage path length and corresponding emission angle of the dark texture area of ​​a single-sided transparent display device according to some embodiments of the present invention. Figure 10 is a data graph showing the variation of pixel pitch and total thickness of a single-sided transparent display device according to some embodiments of the present invention. Figures 11A to 11D are graphs showing the pixel pitch and T1 / T2 of a single-sided transparent display device according to some embodiments of the present invention. Figure 12 is a graph showing the tilt angle (theta) and back-side light leakage brightness of some single-sided transparent display devices according to an embodiment of the present invention when the azimuth angle (phi) is 0°. Figures 13A to 13C are experimental data graphs of distance T1 and pixel pitch of a transparent display device according to some embodiments of the present disclosure. Figures 14A to 14C are schematic cross-sectional views of a transparent display device according to some embodiments of the present disclosure. Implementation

[0008] Figure 1A is a schematic cross-sectional view of a transparent display device 10 according to an embodiment of the present invention. Referring to Figure 1A, the transparent display device 10 includes a transparent display panel 300, a first protective plate 100, and a second protective plate 200. The transparent display panel 300 has a first surface 302 and a second surface 304 opposite to the first surface 302. The first protective plate 100 is located on the first surface 302 of the transparent display panel 300, while the second protective plate 200 is located on the second surface 304 of the transparent display panel 300. In other words, the transparent display panel 300 is located between the first protective plate 100 and the second protective plate 200.

[0009] Figure 1A omits the detailed structure of the transparent display panel 300. The transparent display panel 300 will be further described below with reference to Figures 1B and 1C. Figure 1B is a partially enlarged cross-sectional view of the transparent display device 10 of Figure 1A. Figure 1C is a top view of the transparent display device 10 of Figure 1A. Referring to Figures 1B and 1C, the transparent display panel 300 includes a substrate 310, a circuit structure 320, multiple pixel PXs, and encapsulating adhesive 340. The substrate 310, circuit structure 320, multiple pixel PXs, and encapsulating adhesive 340 are located between the first protective plate 100 and the second protective plate 200.

[0010] In some embodiments, the substrate 310, the first protective plate 100, and the second protective plate 200 all comprise a transparent material. For example, the materials of the substrate 310, the first protective plate 100, and the second protective plate 200 include glass, quartz, organic polymers, or other suitable materials. In some embodiments, the substrate 310, the first protective plate 100, and the second protective plate 200 are rigid substrates, flexible substrates, or stretchable substrates. In some embodiments, the refractive indices of the substrate 310, the first protective plate 100, and the second protective plate 200 are all in the range of 1.4 to 1.6, for example, 1.4, 1.45, 1.5, 1.55, 1.56, 1.57, 1.58, or 1.6. In some embodiments, the substrate 310, the first protective plate 100, and the second protective plate 200 have the same or approximately the same refractive index.

[0011] In this embodiment, the circuit structure 320 is located on the substrate 310, and the second protective plate 200 is bonded to the substrate 310 by a transparent adhesive layer 202. However, this disclosure is not limited thereto. In other embodiments, the substrate 310 may be omitted, and the circuit structure 320 may be formed on the second protective plate 200.

[0012] The circuit structure 320 includes an insulating structure 322 and conductive layers 324 and 326 located within the insulating structure 322. The insulating structure 322 includes one or more insulating layers. The number of conductive layers 324 and 326 in the insulating structure 322 can be adjusted according to actual needs. In this embodiment, the conductive layer 324 is the bottommost conductive layer in the transparent display panel 300. More specifically, the conductive layer 324 is the conductive layer in the insulating structure 322 that is closest to the substrate 310 and the second protective plate 200.

[0013] The transparent display panel 300 includes a plurality of pixels PX arranged in an array along a first direction D1 and a second direction D2, while the first protective plate 100, the transparent display panel 300, and the second protective plate 200 are stacked along a third direction D3. In some embodiments, the first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other.

[0014] Each pixel PX has a spacing P1 in a first direction D1 and a spacing P2 in a second direction. The spacings P1 and P2 determine the resolution of the transparent display panel 300. Each pixel PX includes at least one light-emitting element 330. The pixel PX is disposed above the substrate 310 and bonded to the circuit structure 320. For example, the circuit structure 320 includes a pixel control circuit for controlling the light-emitting element 330, and the light-emitting element 330 is electrically connected to the aforementioned pixel control circuit. In some embodiments, the pixel control circuit includes a thin-film transistor, a capacitor, or other electronic components. In some embodiments, the light-emitting element 330 includes a micro-light-emitting diode, an organic light-emitting diode, or other light-emitting elements.

[0015] Encapsulating adhesive 340 covers the light-emitting element 330. The first protective plate 100 is bonded to the encapsulating adhesive 340. In some embodiments, other materials, such as color filter elements, color conversion elements (e.g., quantum dot materials, fluorescent materials, phosphorescent materials, etc.), adhesive layers, etc., are also included between the first protective plate 100 and the encapsulating adhesive 340, but this disclosure is not limited thereto.

[0016] Referring to Figures 1A, 1B, and 1C, the transparent display panel 300 includes a transmissive area TA and a non-transmissive area NTA. The non-transmissive area NTA is, for example, a mesh, and conductive layers 324, 326 and the light-emitting element 330 are located within the non-transmissive area NTA. Ambient light EL can pass through the non-transmissive area NTA of the transparent display panel 300. Specifically, ambient light EL can sequentially pass through the first protective plate 100, the transparent display panel 300, and the second protective plate 200, and vice versa.

[0017] Referring to Figure 1A, in this embodiment, one of the pixels PX (or the light-emitting element 330) emits light L towards the first protective plate 100. The light L is reflected at the interface between the top surface 102 of the first protective plate 100 and the air, and then propagates towards the second protective plate 200. In some embodiments, after the light L is reflected at the interface between the top surface 102 of the first protective plate 100 and the air, it passes through the first protective plate 100, the transparent display panel 300, and the second protective plate 200, reaching the interface between the bottom surface 204 of the second protective plate 200 and the air, where it is refracted. The portion of the light L that is not reflected by the top surface 102 (not shown) leaves the transparent display device 10 from the top surface 102, and the user US views the image displayed by the transparent display device 10 from the top surface 102.

[0018] In some embodiments, the reflected light L is blocked by other pixels PX, resulting in multiple dark lines forming on the bottom surface 204 of the second protective plate 200. In Figure 1A, the inferred path DL of the light L when it is not blocked is indicated by dashed lines.

[0019] In this embodiment, the orthographic projection m0 of one of the pixels PX onto the bottom surface 204 of the second protective plate 200 forms a first dark ripple m1 to a third dark ripple m3 between the projection m0 onto the side edge 204a of the bottom surface 204 of the second protective plate 200. In this embodiment, the third dark ripple m3 is closest to the side edge 204a of the bottom surface 204; therefore, the third dark ripple m3 can also be called the mmax-th dark ripple. In other embodiments, the number of dark ripples can be adjusted according to requirements; therefore, the mmax-th dark ripple closest to the side edge 204a may also be the second, fourth, fifth, etc., dark ripple. mmax is a positive integer greater than 1.

[0020] θ1 is the reflection angle (or incident angle) of the light ray L emitted by pixel PX corresponding to the first dark ripple m1 on the top surface 102 of the first protective plate 100. θ2 is the reflection angle (or incident angle) of the light ray L emitted by pixel PX corresponding to the second dark ripple m2 on the top surface 102 of the first protective plate 100. θ3 is the reflection angle (or incident angle) of the light ray L emitted by pixel PX corresponding to the third dark ripple m3 on the top surface 102 of the first protective plate 100. This continues if more dark ripples are generated. In this embodiment, θm is the reflection angle (or incident angle) of the light ray L emitted by pixel PX corresponding to the mmaxth dark ripple on the top surface 102 of the first protective plate 100. In this embodiment, the third dark ripple m3 is the mmaxth dark ripple; therefore, θ3 is θm.

[0021] The predicted path DL of the ray corresponding to the first dark fringe m1 enters the interface between the bottom surface 204 and the air at an incident angle θb1 and exits the interface at an exit angle θb1*. The predicted path DL of the ray corresponding to the second dark fringe m2 enters the interface between the bottom surface 204 and the air at an incident angle θb2 and exits the interface at an exit angle θb2*. The predicted path DL of the ray corresponding to the third dark fringe m3 enters the interface between the bottom surface 204 and the air at an incident angle θb3 and exits the interface at an exit angle θb3*. And so on, the predicted path of the ray corresponding to the mmaxth dark fringe enters the interface between the bottom surface 204 and the air at an incident angle θbm (in this embodiment, an incident angle θb3) and exits the interface at an exit angle θbm* (in this embodiment, an exit angle θb3*).

[0022] The exit angles θb1*, θb2*, and θb3* are greater than the incident angles θb1, θb2, and θb3, respectively. In this embodiment, the incident angles θb1, θb2, and θb3 are equal to or approximately equal to the reflection angles θ1, θ2, and θ3, respectively.

[0023] In some embodiments, the pixel pitch of pixel PX (e.g., pitches P1 and P2 in Figure 1C) is 700 micrometers, distance T1 is 1300 micrometers, and distance T2 is 700 micrometers. The resulting reflection angles θ1, θ2, θ3, and θ4 are 15.07 degrees, 26.3 degrees, 38.93 degrees, and 47.12 degrees, respectively. When 47.12 degrees is greater than the critical angle θC1 of the first protective plate 100, the dark fringe corresponding to reflection angle θ4 will disappear due to total internal reflection. The emission angles θb1*, θb2*, and θb3* correspond to angles of 23.11 degrees, 45.72 degrees, and 71.58 degrees, respectively. These angles are for illustrative purposes only and are not intended to be limiting. The reflection angle and emission angle corresponding to the dark fringe can be changed by adjusting the distance T1 and / or the pixel pitch. In this paper, the critical angle θC1 of the first protective plate 100 refers to the angle at which total internal reflection occurs at the interface between the first protective plate 100 and the air, while the critical angle θC2 of the second protective plate 200 refers to the angle at which total internal reflection occurs at the interface between the second protective plate 200 and the air.

[0024] Referring to Figures 1A and 1B, the top surface of the light-emitting element 330 is spaced apart by a distance T1 with respect to the top surface 102 of the first protective plate 100, while the bottom conductive layer 324 is spaced apart by a distance T2 with respect to the bottom surface 204 of the second protective plate 200. In some embodiments, since the thickness of the circuit structure 320 and the light-emitting element 330 is very small, the interference of the thickness of the circuit structure 320 and the light-emitting element 330 on the light path can be ignored. In some embodiments, the total thickness of the circuit structure 320 is 1 micrometer to 100 micrometers, and the total thickness of the light-emitting element 330 is 10 micrometers to 100 micrometers.

[0025] In some embodiments, in addition to forming multiple dark patterns between the orthographic projection m0 and the side edge 204a of the bottom surface 204 of the second protective plate 200, a first dark pattern m1', a second dark pattern m2', and a third dark pattern m3' arranged in sequence are also formed between the orthographic projection m0 and the other side edge 204b of the bottom surface 204. The number of dark patterns between the orthographic projection m0 and the other side edge 204b can also be adjusted as needed.

[0026] In some embodiments, as viewed from the arc-shaped observation surface OS, dark fringes represent regions where the back-side light leakage intensity is 0 or approximately 0. To improve the back-side light leakage problem, the more dark fringes, the better (i.e., the larger mmax, the better), and the closer the reflection angle (equal to reflection angle θ3 in this embodiment) at the top surface 102 corresponding to the mmax dark fringes and the incident angle θbm (in this embodiment, incident angle θb3) at the bottom surface 204 are to the critical angle or 90 degrees, the better. In some embodiments, the difference between the reflection angle θm and the incident angle θbm and the critical angle θC2 of the second protective plate 200 (or the critical angle θC1 of the first protective plate 100) is less than 20 degrees. In some embodiments, the critical angle θC2 of the second protective plate 200 is equal to the critical angle θC1 of the first protective plate 100. In some embodiments, the critical angle θC1 of the first protective plate 100 and the critical angle θC2 of the second protective plate 200 are 30 to 50 degrees, for example, 38 to 46 degrees. In this embodiment, mmax is less than 4, but this disclosure is not limited to this.

[0027] Figure 1D shows the brightness distribution of back-side light leakage of the transparent display device in Figure 1A from various viewing angles. As can be seen from Figure 1D, since the non-transparent area below pixel PX contains vertically distributed stripes and horizontally distributed stripes, the first dark stripe m1, m1', the second dark stripe m2, m2', and the third dark stripe m3, m3' will also appear as stripes.

[0028] Figures 2A to 2H show simulation data graphs illustrating the relationship between the difference between the incident angle θbm corresponding to the dark pattern of the transparent display device in some embodiments and the critical angle θC2 of the second protective plate, and the number of dark patterns mmax. Figures 2A to 2H show the difference between the incident angle θb(mmax) corresponding to the mmaxth dark pattern and the incident angle θb(mmax-1) corresponding to the mmaxth dark pattern and the critical angle θC2 of the second protective plate 200, where the incident angles θb(mmax) and θb(mmax-1) are the incident angles of the predicted forward path DL (refer to Figure 1A) at the bottom surface 204. In the simulation experiments of Figures 2A to 2H, the first and second protective plates have the same refractive index and critical angle. In the simulation experiments of Figures 2A to 2D, when the refractive index n of the second protective plate 200 is 1.4, the critical angle θC2 of the second protective plate 200 is 45.58 degrees. In the simulation experiments shown in Figures 2E to 2H, when the refractive index n of the second protective plate 200 is 1.6, the critical angle θC2 of the second protective plate 200 is 38.68 degrees. In the simulation experiments shown in Figures 2A to 2H, the pixel spacing is, for example, the spacing P1 and spacing P2 shown in Figure 1C.

[0029] In the simulation experiment shown in Figure 2A, with a pixel pitch of 100 micrometers and a distance T1 (refer to Figure 1B) of 100 micrometers, mmax is 2, the incident angle θb2 corresponding to the second dark fringe is 45 degrees, and the incident angle θb1 corresponding to the first dark fringe is 26.5 degrees. In the simulation experiment shown in Figure 2E, with a pixel pitch of 100 micrometers and a distance T1 (refer to Figure 1B) of 100 micrometers, mmax is 1, and the incident angle θb1 corresponding to the first dark fringe is 26.5 degrees.

[0030] In Figure 2E, due to total internal reflection, the second dark fringe will not appear. The incident angle θb(2) corresponding to the second dark fringe (Figure 1A) is shown to be greater than the critical angle θC2 of the second protective plate 20°, that is, greater than 38.68 degrees. In Figures 2A to 2H, when total internal reflection occurs, the incident angle θb(m) is substituted with zero. This means that the difference between the incident angle θb(m) and the critical angle θC2 is equal to the critical angle θC2, which means that the corresponding dark fringe will not form.

[0031] Figures 3A, 4A, and 5A are schematic cross-sectional views of a transparent display device according to some embodiments of the present invention. Figures 3A, 4A, and 5A omit the transparent display panel in the transparent display device, and the distances T1 and T2 are changed by adjusting the thickness of the first protective plate 100 and the thickness of the second protective plate 200.

[0032] In the embodiments shown in Figures 3A to 5A, a 16.1-inch transparent display device is used for simulation, where the pixel pitches P1 and P2 (see Figure 1C) are both 700 micrometers, and both the first protective plate 100 and the second protective plate 200 include glass. In the embodiment of Figure 3A, the distance T1 is 2.0 mm, and the distance T2 is 0.5 mm. In the embodiment of Figure 4A, the distance T1 is 2.0 mm, and the distance T2 is 2.5 mm. In the embodiment of Figure 5A, the distance T1 is 5.0 mm, and the distance T2 is 2.5 mm.

[0033] Figures 3B, 4B, and 5B are irradiance distribution diagrams of back-side light leakage of a single light-emitting element 330 in the transparent display device of Figures 3A, 4A, and 5A at various viewing angles. In Figures 3B, 4B, and 5B, the irradiance is normalized. From Figures 3B to 5B, it can be seen that increasing the number of dark fringes on one side (i.e., the mmax value) and making the emission angle θbm* corresponding to the mmax-th dark fringe closer to 90 degrees can improve the back-side light leakage problem.

[0034] Figure 6 is an optical path diagram of the light emitted by one of the pixels PX0 of a transparent display device according to an embodiment of the present invention. Referring to Figure 6, the light L emitted by pixel PX0 arrives at the top surface 102 of the first protective plate 100 at an incident angle and is reflected at the top surface 102 of the first protective plate 100 at a reflection angle θa. Since the aforementioned incident angle is equal to the reflection angle θa, it is represented by θa in Figure 5.

[0035] For the reflected ray L to be able to be occluded by another pixel PXa, the following must be satisfied (mathematical formula A). (Mathematical formula A)

[0036] In mathematical formula 1, ma represents the nth pixel next to pixel PX0 that ray L is occluded by. For example, ma = 1 means ray L is occluded by the first pixel next to pixel PX0, ma = 2 means ray L is occluded by the second pixel next to pixel PX0, and ma = mmax means ray L is occluded by the mmaxth pixel next to pixel PX0. When ma = mmax, θa is close to the critical angle θC1, critical angle θC2, or 90 degrees, i.e., θa = θm. In some embodiments, ma is an integer less than 5, such as 1, 2, 3, or 4. Additionally, in mathematical formula A, the pixel spacing is, for example, spacing P1 or spacing P2 in Figure 1C, while the distance T1 can be referred to in Figure 1B.

[0037] On the other hand, the total path D of the ray L from pixel PX0 to the bottom surface 204 can be calculated by the following (mathematical formula B). (Mathematical expression B)

[0038] In mathematical formula B, the incident angle θa' is, for example, equal to the reflection angle θa. In this disclosure, the light leakage path length in the dark freckle area is defined as the length of light ray L from pixel PX0, reflected by the top surface 102 to pixel PXa, plus the length of the inferred path DL of light ray from pixel PXa to the bottom surface 204. Table A calculates the light leakage path length in the dark freckle area of ​​the transparent display device of some embodiments, and the incident angle θa' / reflection angle θa corresponding to the dark freckle, using (mathematical formula A) and (mathematical formula B). Referring also to Figures 1A to 1C, in the embodiments of Table A, the distance T1 is 1300 micrometers, the distance T2 is 700 micrometers, the refractive index of the first protective plate 100 and the second protective plate 200 is 1.56, and the critical angle θC1 of the first protective plate 100 and the critical angle θC2 of the second protective plate 200 are 47 degrees, and the pixel spacing P1 and spacing P2 are 700 micrometers. Table A Length of light leakage path in dark texture area The incident angle θa' / reflection angle θa corresponding to the dark pattern The exit angle from the bottom surface 204 into the air The first dark pattern 3417.5 μm 15 degrees 23.8 The second dark pattern 3747.99 μm 28.3 degrees 47.7 The third dark pattern 4241.97 μm 38.9 degrees 78.4 Fourth dark pattern 3747.99 μm 47.1 degrees

[0039] In Table A, the angle of incidence of the fourth dark fringe at the interface between the bottom surface 204 and the air is greater than the critical angle θC2 for total internal reflection. Since total internal reflection will occur whenever the angle of incidence is greater than the critical angle θC2, the fourth dark fringe will not form. That is to say, in the embodiment in Table A, the third dark fringe is the mmaxth dark fringe, and θm is 38.9 degrees.

[0040] The back-side light leakage intensity distribution was measured using an Eldim optical viewing angle meter, and the results are shown in Figure 1D. The measurement results confirm that a fourth dark fringe will not form.

[0041] On the other hand, since the reflection angle θa is equal to the incident angle θa', we can obtain (mathematical formula C). (Mathematical formula C)

[0042] Simplifying (mathematical expression C) yields (mathematical expression D). = (Mathematical expression D)

[0043] The distance d1 between the occluded pixel and the luminous pixel corresponding to the mmax-th dark fringe is equal to the pixel spacing multiplied by mmax. Meanwhile, d2, substituted with the pixel spacing, yields (mathematical expression E). = (Mathematical expression E)

[0044] Simplifying (mathematical expression E), we can obtain (mathematical expression F). = (Mathematical expression F)

[0045] On the other hand, by substituting mmax for ma and θm for θa in (mathematical expression A) and rearranging them, we can obtain (mathematical expression G). = (Mathematical expression G)

[0046] In addition, in order to increase , Ideally, the angle should be as close as possible to the critical angle θC1 of the first protective plate or the critical angle θC2 of the second protective plate. Taking the critical angle θC1 of the first protective plate as an example, combined with (mathematical formula A), we can obtain (mathematical formula H). (Mathematical expression H)

[0047] In (mathematical formula H), n is the refractive index of the first protective plate 100, and T1min refers to... Just equal to The thickness of the first protective plate 100 corresponding to that time. On the other hand, based on some experimental results, and A difference of less than 20 degrees can improve the problem of light leakage at the back. For example, referring to Figure 1D, the measured width of the dark ripples is approximately 10 degrees. This is the measurement result when the light-shielding width of the pixel array is 100µm and the pixel pitch is 700µm. Generally, the light-shielding width of transparent displays is designed to be between 100µm and 200µm. Therefore, the estimated maximum width of the dark ripples is twice 10 degrees, i.e., 20 degrees. and The difference is less than 20 degrees. Therefore, this disclosure is based on... and The maximum value T1max of the thickness of the first protective plate 100 is calculated based on the difference being less than 20 degrees, as shown in (Mathematical Formula I). (Mathematical Formula I)

[0048] In (Mathematical Expression I), for -20 degrees.

[0049] Based on the above, when the thickness T1 of the first protective plate 100 falls between T1max and T1min, the difference between the reflection angle θa and θC1 corresponding to the mmaxth dark ripple is less than 20 degrees. In other words, referring to Figure 1A, the difference between the incident angle θbm corresponding to the dark ripple closest to the bottom surface 204a of the second protective plate 200 at the bottom surface 204 and the critical angle θC2 of the second protective plate 200 at the bottom surface 204 is less than 20 degrees. Referring to Figure 5, when the critical angle θC1 of the first protective plate 100 is equal to the critical angle θC2 of the second protective plate 200, it also means that the difference between the incident angle θa' corresponding to the mmaxth dark ripple and θC2 is less than 20 degrees.

[0050] Figures 7A, 7B, 8A, 8B, 9A, and 9B are data diagrams showing the light leakage path length and corresponding exit angle of the dark ridge area of ​​a transparent display device according to some embodiments of the present invention. In Figures 7A to 9B, the light leakage path length of the dark ridge area is calculated using (Mathematical Formula B), while the corresponding exit angle is first calculated using (Mathematical Formula A) to obtain the incident angle θa' corresponding to the dark ridge (refer to Figure 6), and then the exit angle of the light after leaving the second protective plate is calculated using the refractive indices of the first protective plate, the second protective plate, and air. It should be noted that in the dark ridge area, the light is actually blocked by the non-transparent area in the transparent display panel; therefore, the exit angle here is only a simulated angle (as shown in Figure 1A, the angle of the inferred path DL). In reality, no light or only a small amount of light leaves the second protective plate at such an exit angle. Furthermore, in Figures 7A to 9B, one circle represents one dark ridge.

[0051] In Figures 7A, 8A, and 9A, the transparent display device conforms to the configuration in Table B. Table B [distance] [T1] 1600 micrometers 1300 micrometers 1000 micrometers 700 micrometers [distance] [T2] 400 micrometers 700 micrometers 1000 micrometers 1300 micrometers [T2 / T1] 4.0 1.9 1.0 0.5

[0052] In Figures 7B, 8B, and 9B, the transparent display device conforms to the configuration in Table C. Table C [distance] [T1] 3200 micrometers 2600 micrometers 2000 micrometers 1400 micrometers [distance] [T2] 800 micrometers 1400 micrometers 2000 micrometers 2600 micrometers [T2 / T1] 4.0 1.9 1.0 0.5

[0053] Figure 10 is a data graph showing the variation of pixel pitch and total thickness of a transparent display device according to some embodiments of the present invention. In Figure 10, the vertical axis represents the total thickness of the sum of distances T1 and T2, while the horizontal axis represents the pixel pitch (e.g., pitch P1 or pitch P2 in Figure 1C). In Figure 10, with a fixed distance T1 and pixel pitch, the value of distance T2 is calculated using (Mathematical Formula F) and (Mathematical Formula G). For example, adding the obtained distance T2 to distance T1 yields the total thickness shown in Figure 9.

[0054] In Figure 10, a transparent display device with a distance T1 of 5600 micrometers can be used, for example, in automotive display panels; a transparent display device with a distance T1 of 2800 micrometers can be used, for example, in large-size splicing display panels; a transparent display device with a distance T1 of 1400 micrometers can be used, for example, in notebook computers or desktop computers; and a single-sided transparent display device with a distance T1 of 700 micrometers can be used, for example, in Retina displays. However, this disclosure is not limited to these. Transparent display devices with different distances T1 can also be applied to other types of display devices.

[0055] Figures 11A to 11D are data diagrams of pixel pitch and T1 / T2 of a single-sided transparent display device according to some embodiments of the present invention. In Figures 11A to 11C, the T1 / T2 values ​​are calculated using (Mathematical Formula F) and (Mathematical Formula G).

[0056] Figure 12 is a graph showing the tilt angle (theta) versus back-side light leakage brightness of some transparent display devices according to an embodiment of the present invention when the azimuth angle (phi) is 0°. In Figure 12, the pixel pitch of the transparent display devices in Experimental Examples 1, 2, and 3 is 700 micrometers, and the first and second protective plates are made of glass with a refractive index of 1.51. The configurations of Experimental Examples 1, 2, and 3 are shown in Tables D, E, and F, respectively. Table D [Experimental Example] [1] Pixel spacing 700 micrometers Distance from T1 1350 micrometers Distance from T2 1800 micrometers Distance T1 / Pixel Spacing 1.92 Total backside light leakage brightness 12113 nits Front total brightness 125469 nits Backside light leakage percentage 9.65% Table E [Experimental Example] [2] Pixel spacing 700 micrometers Distance from T1 1350 micrometers Distance from T2 700 micrometers Distance T1 / Pixel Spacing 1.92 Total backside light leakage brightness 10,000 nits Front total brightness 111085 nits Backside light leakage percentage 9.0% Table F [Experimental Example] [3] Pixel spacing 700 micrometers Distance from T1 900 micrometers Distance from T2 700 micrometers Distance T1 / Pixel Spacing 1.28 Total backside light leakage brightness 6677 nits Front total brightness 80918 nits Backside light leakage percentage 8.2%

[0057] As shown in Figure 12, the emission angles corresponding to the dark patterns of the transparent display devices in Experimental Examples 1, 2, and 3 are as shown in Table G. Table G The angle of attack corresponding to the first dark pattern The angle of attack corresponding to the second dark pattern The angle of attack corresponding to the third dark pattern Experimental Example 1 23.0 degrees 45.8 degrees 73.2 degrees Experimental Example 2 23.0 degrees 45.8 degrees 73.2 degrees Experimental Example 3 34.4 degrees 73.3 degrees

[0058] As can be seen from Tables D to F and Figure 12, the total brightness of back-side light leakage will change significantly with the change of distance T1 / pixel spacing, and the number of dark lines can also be changed by adjusting the distance T1 / pixel spacing.

[0059] Figures 13A to 13C are experimental data diagrams of the distance T1 and pixel pitch of a transparent display device according to some embodiments of the present disclosure. In Figures 13A to 13C, the structure of the transparent display device is shown in Figure 1A, wherein the first protective plate 100 and the second protective plate 200 have the same refractive index. In Figures 13A to 13C, the pixel pitch is, for example, the pitch P1 or pitch P2 in Figure 1C. From Figures 13A to 13C, it can be observed that the number of dark lines on one side (i.e., the mmax value) is related to the refractive index of the protective plate and the ratio of the distance T1 to the pixel pitch (i.e., the ratio of the distance T1 to the pixel pitch). Related to, and among them The higher the slope (corresponding to the slope of the data lines in Figures 13A to 13C), the larger the mmax tends to be.

[0060] Table H shows experimental data for some examples disclosed herein. In the experiments in Table H, the structure of the transparent display device is shown in Figure 1A, where the refractive index of the first protective plate 100 is equal to the refractive index of the second protective plate 200. The refractive indices n of the first protective plate 100 and the second protective plate 200 were adjusted, and the corresponding values ​​for the number of dark fringes on different sides (i.e., mmax values) were calculated. The results are shown in Table H. Table H [First Protection Plate]

[0100] [With the second protective plate]

[0200] [Refractive index] [n] [n=1.4] [n=1.45] [n=1.5] [n=1.55] [n=1.6] [m, max , =1] 0.49 0.52 0.56 0.59 0.62 [m, max =2] 1.04 1.14 1.25 1.36 1.48 [m, max =3] 1.47 1.57 1.68 1.78 1.87 [m, max =4] 1.91 2.09 2.27 2.45 2.65 [m, max =5] 2.42 2.6 2.77 2.95 3.12

[0061] Table I presents experimental data for some examples disclosed herein. In the experiments in Table I, the structure of the transparent display device is shown in Figures 14A to 14C, wherein in the structures of Figures 14B and 14C, the second protective plate comprises a multi-layer structure. Furthermore, in the experiments in Table I, the refractive index of the first protective plate 100 and the second protective plate 200 is 1.51, and the pixel pitch of the pixel PX is 700 micrometers. Back-side light leakage brightness was tested at different tilt angles with an azimuth angle of 0°. The back-side light leakage brightness was measured using an Eldim optical viewing angle detector. The results are shown in Table I. Table I [Structure of a transparent display device] [Image] [14A] [Image] [14B] [Image] [14B] [picture] [14C] [picture] [14A] [T1(] [millimeters] [)] 1.3 1.3 1.3 1.3 1.7 [T2(] [millimeters] [)] 0.7 X1=0.7 X2=1.1 X1=0.7 X2=0.4 X1=0.7 X2=0.4 X3=1.1 0.7 [Positive Perspective] [(0, 0)] [brightness] [ (nits)] 1000 1000 1000 1000 1000 [Backside light leakage brightness] [(nits)] [Pitch angle] [=0˚] 9.22 12.38 12.25 8.25 12.49 [Pitch angle] [=-5˚] 16.15 20.29 18.42 12.69 48.27 [Pitch angle] [=-10˚] 16.3 22.17 17.06 11.39 44.49 [Pitch angle] [=-15˚] 17.77 22.01 15.68 10.42 32.45 [Pitch angle] [=-20˚] 11.47 15.49 10.78 6.69 32.34 [Pitch angle] [=-25˚] 22.77 25.6 13.54 9.03 38.20 [Pitch angle] [=-30˚] 23.44 30.4 14.61 9.72 30.06 [Pitch angle] [=-35˚] 27.8 35.29 13.01 9.51 16.20 [Pitch angle] [=-40˚] 16.3 19.9 10.49 7.09 22.18 [Pitch angle] [=-45˚] 44.59 52.22 14.67 10.21 23.58 [Pitch angle] [=-50˚] 60.25 64.98 16.6 11.12 22.68 [Pitch angle] [=-55˚] 73.05 85.78 18.55 14.69 20.80 [Pitch angle] [=-60˚] 59.07 62.33 17.53 12.42 23.37 [Pitch angle] [=-65˚] 43.61 50.81 17.96 14.63 31.77 [Pitch angle] [=-70˚] 179.37 205.12 53.41 44.39 43.04 [Pitch angle] [=-75˚] 251.21 269.4 81.9 67.16 42.03 [Pitch angle] [=-80˚] 347.29 351.47 118.76 95.98 31.91 [Pitch angle] [=-85˚] 324.69 420.48 135.99 101.57 104.43

[0062] Table I shows that the change in distance T2 has no significant effect on the emission angle of the dark fringes.

[0063] Based on the above experimental results, this disclosure proposes some transparent display devices in which the spacing P1 (refer to Figure 1C), spacing P2 (refer to Figure 1C), distance T1 (refer to Figure 1A), and the refractive index n of the first protective plate meet the conditions in Table 1, which can effectively improve the problem of back-side light leakage. Table 1 [P1] [P2] [T1] [n] 550 micrometers 550 micrometers 1524 micrometers 1.51 560 micrometers 560 micrometers 1551 micrometers 1.51 570 micrometers 570 micrometers 1579 micrometers 1.51 580 micrometers 580 micrometers 1607 micrometers 1.51 590 micrometers 590 micrometers 1634 micrometers 1.51 600 micrometers 600 micrometers 1662 micrometers 1.51 610 micrometers 610 micrometers 1690 micrometers 1.51 620 micrometers 620 micrometers 1717 micrometers 1.51 630 micrometers 630 micrometers 1745 micrometers 1.51 640 micrometers 640 micrometers 1773 micrometers 1.51 650 micrometers 650 micrometers 1801 micrometers 1.51 660 micrometers 660 micrometers 1828 micrometers 1.51 670 micrometers 670 micrometers 1856 micrometers 1.51 680 micrometers 680 micrometers 1884 micrometers 1.51 690 micrometers 690 micrometers 1911 micrometers 1.51 700 micrometers 700 micrometers 1939 micrometers 1.51

[0064] 10: Transparent display device 100: First protective plate 102: Top 200: Second protection board 202: Transparent adhesive layer 204: Bottom 204a, 204b: Side 300: Transparent display panel 302: First Page 304: Second page 310:Substrate 320: Circuit Structure 322: Insulation structure 324, 326: Conductive layers 340: Encapsulating adhesive D1: First Direction D2: Second Direction D3: Third direction DL: Predicting the route forward EL: Ambient Light L: Light m0: Orthographic projection m1, m1': The first dark pattern m2, m2': The second dark pattern m3, m3': The third dark line OS: Arc-shaped observation surface P1, P2: Spacing PX0, PX, PXa: pixel T1, T2: Distance TA: Penetration Zone US: User NTA: Non-penetrating zone θ1, θ2, θ3, θa: Reflection angles θb1, θb2, θb3, θa': incident angle θb1*, θb2*, θb3*: Exit angles θC1, θC2: Critical angles

Claims

1. A transparent display device, comprising: A transparent display panel has a first surface and a second surface opposite to the first surface. The transparent display panel includes a plurality of pixels arranged in an array along a first direction and a second direction, wherein the pixels have a spacing P1 in the first direction and a spacing P2 in the second direction, and each pixel includes at least one light-emitting element. A first protective plate is located on the first surface of the transparent display panel, wherein the first protective plate is positioned above the at least one light-emitting element, and the at least one light-emitting element is separated from the top surface of the first protective plate by a distance T1. The spacing P1, the spacing P2, the distance T1, and the refractive index n of the first protective plate conform to the conditions in Table 1: Table 1 P1 P2 T1 n 550 μm 550 μm 1524 μm 1.51 560 μm 560 μm 1551 μm 1.51 570 μm 570 μm 1579 μm 1.51 580 μm 580 μm 1607 μm 1.51 590 micrometers 1634 micrometers 1.51 600 micrometers 1662 micrometers 1.51 610 micrometers 1690 micrometers 1.51 620 micrometers 1717 micrometers 1.51 630 micrometers 1745 micrometers 1.51 640 micrometers 1773 micrometers 1.51 650 micrometers 1801 micrometers 1.51 660 micrometers 1828 micrometers 1.51 670 micrometers 1856 micrometers 1.51 680 micrometers 1884 micrometers 1.51 690 micrometers 1911 micrometers 1.51 700 micrometers 1939 micrometers 1.51 2. The transparent display device as claimed in claim 1, wherein the at least one light-emitting element comprises a micro light-emitting diode, and the transparent display panel comprises an encapsulating adhesive that covers the at least one light-emitting element.

3. The transparent display device as described in claim 1, further comprising: A second protective plate is located on the second surface of the transparent display panel, and the transparent display panel is located between the first protective plate and the second protective plate, wherein an ambient light passes through the first protective plate, the transparent display panel and the second protective plate in sequence.

4. The transparent display device as claimed in claim 3, wherein the transparent display panel further includes a substrate, wherein the pixels are disposed above the substrate, and the substrate is located between the pixels and the second protective plate.

5. The transparent display device as claimed in claim 3, wherein light emitted from one of the pixels is reflected at the top surface of the first protective plate and forms multiple dark lines at the bottom surface of the second protective plate, wherein the difference between the incident angle θbm of one of the dark lines closest to the bottom surface of the second protective plate at the bottom surface of the second protective plate and the critical angle θC2 of the interface between the second protective plate and the air is less than 20 degrees.

6. A transparent display device, comprising: A transparent display panel having a first surface and a second surface opposite to the first surface, wherein the transparent display panel includes a plurality of pixels and the pixels have a pixel pitch in a first direction, wherein each pixel includes at least one light-emitting element; a first protective plate located on the first surface of the transparent display panel, and the at least one light-emitting element is spaced apart from the top surface of the first protective plate by a distance T1, the first protective plate having a refractive index n, and the transparent display device conforming to the following (Mathematical Formula 1), (Mathematical Formula 2) and (Mathematical Formula 3), where ma is an integer less than 5: = (Mathematical Formula 1); -20˚= (Mathematical Formula 2); (Mathematical Formula 3).

7. The transparent display device as described in claim 6, further comprising: A second protective plate is located on the second surface of the transparent display panel, and the transparent display panel is located between the first protective plate and the second protective plate, wherein an ambient light passes through the first protective plate, the transparent display panel and the second protective plate in sequence.

8. The transparent display device as claimed in claim 6, wherein the refractive index n of the first protective plate is 1.5, and the distance T1 / spacing P1 is 0.56, 1.25, 1.68, 2.27, or 2.

77.

9. The transparent display device as claimed in claim 6, wherein the refractive index n of the first protective plate is 1.45, and the distance T1 / spacing P1 is 0.52, 1.14, 1.57, 2.09, or 2.

6.

10. The transparent display device as claimed in claim 6, wherein the refractive index n of the first protective plate is 1.55, and the distance T1 / spacing P1 is 0.59, 1.36, 1.78, 2.45, or 2.95.

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