Transparent display

Abstract

To provide a transparent display with which it is possible to prevent light irradiated with when a light source is turned on from leaking to the reverse side of the display.SOLUTION: The transparent display is constructed such that a plurality of LEDs 4 are arranged between multiple sets of electrodes 2, 3 arranged in array form on a transparent substrate 1, and a plurality of openings 20 where the electrodes 2, 3 are not located, are provided in array form so as to enable light to pass through the plurality of openings 20. On an optical path in a direction leading from a section of the reverse side of the LEDs 4 facing a space between the electrodes 2, 3 toward the transparent substrate 1, a light-shielding layer 11 is located in a target region including a region that shields the optical path, so that irradiation with light in a direction leading from the reverse side of the LEDs 4 toward the transparent substrate 1 is blocked by the light-shielding layer 11 and the irradiation light of the LEDs 4 is prevented from leaking to the reverse side of the display.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transmissive display, and is particularly suitable for use in a transmissive display in which a plurality of light sources are arranged between a plurality of sets of electrodes arranged in an array on a transparent substrate, and a plurality of openings are provided in which no electrodes are arranged, thereby allowing light to pass through the plurality of openings. [Background technology]

[0002] Conventionally, transmissive displays have been known that are different from general displays in that they allow the viewer to see through to what is behind them. Transmissive displays have multiple light sources arranged in an array on a transparent substrate, and multiple openings where no electrodes are arranged are provided, allowing light to pass from the back side of the display to the front side through the openings. The ratio of the area of ​​the openings to the area of ​​one pixel is called the aperture ratio, and the larger the aperture ratio, the more background light can be taken in, resulting in a display that appears almost transparent.

[0003] There are various types of transmissive displays, among which transmissive LED displays can achieve a high transmittance of 70% or more, and are therefore expected to be used in a variety of applications. When configuring a transmissive LED display, it is preferable to use a technology called micro LED, in which LEDs used as light sources are miniaturized and arranged in an array. Displays using micro LEDs are disclosed in, for example, Patent Documents 1 to 3.

[0004] Fig. 7 is a simplified diagram showing the structure of the light-emitting section of a transmissive LED display. Fig. 7(a) shows the light-emitting section of the transmissive LED display as viewed from the front side, and Fig. 7(b) shows the light-emitting section of the transmissive LED display as viewed from the back side. As shown in Fig. 7, a plurality of LEDs 101 are arranged in an array, and a plurality of openings 102 are arranged in an array adjacent to the plurality of LEDs 101. Each of the plurality of LEDs 101 is arranged between an anode electrode 103 and a cathode electrode 104.

[0005] However, in the transmissive LED display configured as above, there is a problem that the light of the LED 101 emitted to project information on the front surface leaks to the back surface through the gap between the anode electrode 103 and the cathode electrode 104. That is, as shown in FIG. 7(b), when the transmissive LED display is viewed from the back surface side, a part of the LED 101 is visible through the gap between the anode electrode 103 and the cathode electrode 104. In the transmissive LED display, not only the substrate disposed on the front side of the LED 101 is made of a transparent substrate, but also the substrate disposed on the back side of the LED 101 is made of a transparent substrate. Therefore, when the LED 101 is turned on, light leaks from the back surface of the LED 101 through the gap between the electrodes 102 and 103 to the back surface of the display. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-052156 [Patent Document 2] JP 2022-093393 A [Patent Document 3] WO2023-127585 publication Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve such problems, and aims to prevent light emitted when a light source is turned on in a transmissive display from leaking to the back surface of the display. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a transmissive display in which a plurality of light sources are arranged between a plurality of sets of electrodes arranged in an array on a transparent substrate, and a plurality of openings in which no electrodes are arranged are provided in an array so that light can be transmitted through the plurality of openings.A light-shielding layer is arranged in a target area including an area that blocks the optical path from a portion of the back surface of the light source facing the gap between the electrodes toward the transparent substrate. Effect of the Invention

[0009] According to the present invention configured as described above, in a transmissive display, when a light source is turned on, light irradiated from the back surface of the light source toward the transparent substrate is blocked by a light-shielding layer, thereby preventing the light irradiated by the light source from leaking to the back surface of the display. [Brief description of the drawings]

[0010] [Figure 1] 1A to 1C are diagrams illustrating an example of the configuration of a light-emitting structure with a leakage prevention function that is applied to the transmissive LED display according to this embodiment. [Diagram 2] 1A to 1C are diagrams illustrating the light blocking effect of the light emitting structure with leakage prevention function according to the present embodiment. [Diagram 3] 1A to 1C are diagrams illustrating an example of a manufacturing process of the light emitting structure with leakage prevention function according to the present embodiment. [Figure 4] 1 is a diagram showing an example of an array arrangement of light-emitting structures with leakage prevention functions according to an embodiment of the present invention; [Diagram 5] 10A and 10B are diagrams illustrating another example of an array arrangement of the light-emitting structures with leakage prevention functions according to the present embodiment. [Figure 6]11A and 11B are diagrams showing modified examples of the light-emitting structure with leakage prevention function including a light-shielding layer according to the present embodiment. [Figure 7] 1A and 1B are diagrams showing the structure of a light-emitting part of a transmissive LED display. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of the present invention will be described below with reference to the drawings. The transmissive display of this embodiment is a transmissive display in which a plurality of light sources are arranged between a plurality of sets of electrodes arranged in an array on a transparent substrate, and a plurality of openings are provided in which no electrodes are arranged, so that light can be transmitted through the plurality of openings. This allows background light to be transmitted from the rear surface to the front surface of the display, so that the back of the display can be seen through from the front side.

[0012] In this embodiment, a structure for preventing light leakage to the back surface is applied to a light emitting structure of a transmissive LED display using micro LED elements as an example of a light source. In the following description, the term "light emitting structure with leakage prevention function" refers to a light emitting structure including the light leakage prevention structure of this embodiment, and is distinguished from a light emitting structure that does not include the light leakage prevention structure.

[0013] Fig. 1 is a diagram showing a configuration example of a light emitting structure 10 with a leakage prevention function applied to a transmissive LED display according to this embodiment. Fig. 1 shows a cross-sectional configuration of the light emitting structure 10 with a leakage prevention function when the transmissive LED display is viewed from the side, with the upper part of the figure showing the front surface of the display and the lower part of the figure showing the back surface of the display. Fig. 1 shows two light emitting structures 10 with a leakage prevention function arranged side by side, but in reality, more light emitting structures 10 with a leakage prevention function are arranged in an array (see Figs. 4 and 5, which will be described later).

[0014] As shown in Fig. 1, one light-emitting structure 10 with leakage prevention function has a pair of an anode electrode 2 and a cathode electrode 3 arranged at a predetermined interval on a transparent substrate 1, and an LED 4 is disposed between and electrically connected to the electrodes 2, 3. In the example of Fig. 1, two electrode pads 6 are disposed in two contact holes 5 formed in two insulating layers 8, 9 on the electrodes 2, 3, and the LED 4 is mounted by a conductive adhesive 7 formed on the electrode pads 6.

[0015] Between two adjacent light-emitting structures 10 with leakage prevention function, an opening 20 is provided where the electrodes 2, 3 are not arranged. The opening 20 is configured to allow light to pass from the back surface to the front surface of the transmissive LED display, so that the back of the transmissive LED display can be seen from the front side.

[0016] In this embodiment, a light-shielding layer 11 is provided for the light-emitting structure configured as above. This light-shielding layer 11 is a light leakage prevention structure. The light-shielding layer 11 is disposed in a target area including a region that blocks the light path on the light path from a portion of the back surface of the LED 4 facing the gap between the electrodes 2 and 3 toward the transparent substrate 1. In the example of FIG. 1, the light-shielding layer 11 is disposed in a target area that includes a region that blocks the light path and covers the gap between the electrodes 2 and 3 on the front side of the gap.

[0017] The light-shielding layer 11 should have high light-shielding properties so that it can block even high-energy emitted light. For example, it should have an optical density (OD value), which is an index showing the amount of light transmitted (transmittance), of "3" or more (transmittance of 0.1% or less). This is in consideration of the fact that the OD value of the black matrix formed in the backlight of a liquid crystal display device to prevent light leakage and RGB color mixing is set to approximately "3."

[0018] Fig. 2 is a diagram showing the light blocking effect of the light emitting structure 10 with leakage prevention function according to this embodiment configured as described above, in comparison with a conventional light emitting structure. Fig. 2(a) shows the conventional light emitting structure, and Fig. 2(b) shows the light emitting structure 10 with leakage prevention function according to this embodiment. As shown in Fig. 2, when the LED 4 is turned on, light is emitted not only from the front surface of the LED 4 but also from the back surface.

[0019] In the case of the conventional light-emitting structure shown in Fig. 2(a), light irradiated from the back surface of the LED 4 toward the transparent substrate 1 leaks through the gap between the electrodes 2 and 3 to the back surface of the transparent substrate 1. In contrast, in the case of the light-emitting structure 10 with leakage prevention function of this embodiment shown in Fig. 2(b), light irradiated from the back surface of the LED 4 toward the transparent substrate 1 is blocked by the light-shielding layer 11 arranged to cover the gap between the electrodes 2 and 3. Therefore, the light irradiated from the back surface of the LED 4 is prevented from leaking through the gap between the electrodes 2 and 3 to the back surface of the transparent substrate 1.

[0020] Fig. 3 is a diagram showing an example of a manufacturing process of the light emitting structure 10 with leakage prevention function shown in Fig. 1. Note that the materials and steps described below are merely examples and are not limited to these.

[0021] First, an anode electrode 2 and a cathode electrode 3 are formed on a transparent substrate 1 (step S1). The electrodes 2 and 3 can be made of materials such as Au, Ag, Cu, AgMg, Al, and ITO. The process mainly uses a photolithography process. The arrangement of the electrodes 2 and 3 is not limited to a simple matrix or active matrix, and may be an irregular arrangement.

[0022] Next, a first insulating layer 8 is formed on the transparent substrate 1 by vapor deposition, sputtering, spin coating, or the like so as to cover the electrodes 2 and 3 (step S2). Examples of materials that can be used for the first insulating layer 8 include SiNx, SiOx, and acrylic resin.

[0023] Next, a light-shielding layer 11 is formed on the first insulating layer 8 in a target area covering the gap between the electrodes 2 and 3 (step S3). For example, a light-shielding material is applied on the first insulating layer 8 by deposition or spin coating, and the light-shielding layer 11 is formed in the target area covering the area between the anode electrode 2 and the cathode electrode 3 by a photolithography process. For example, a photosensitive resin containing a black pigment, chromium oxide, or the like can be used as the light-shielding material.

[0024] Next, a second insulating layer 9 is formed on the first insulating layer 8 by deposition, sputtering, spin coating, or the like so as to cover the light-shielding layer 11 (step S4). Examples of materials that can be used for the second insulating layer 9 include SiNx, SiOx, and acrylic resin. Since the second insulating layer 9 also serves the role of planarization, it is desirable for the film thickness to be thicker than that of the first insulating layer 8.

[0025] Next, contact holes 5 are formed on the electrodes 2 and 3 by photolithography and etching (step S5). Furthermore, electrode pads 6 are formed in the contact holes 5 mainly by photolithography, and the electrode pads 6 are electrically connected to the electrodes 2 and 3 (step S6). Examples of materials that can be used for the electrode pads 6 include Au, Ag, Cu, AgMg, Al, and ITO.

[0026] Finally, after forming a conductive adhesive 7 on the electrode pad 6, the LED 4 is mounted (step S7). For example, solder, ACF (anisotropic conductive film), or a material in which conductive particles are dispersed in resin can be used as the conductive adhesive 7. Mounting is performed by placing the LED 4 in the correct position, and then reflowing the adhesive if solder is used, or by applying pressure and heat to solidify the adhesive if other materials are used.

[0027] Fig. 4 is a schematic diagram showing an example of an array arrangement of the light emitting structure 10 with leakage prevention function, in comparison with an array arrangement of a conventional light emitting structure. Fig. 4(a) shows the array arrangement of the conventional light emitting structure, as viewed from the backside of the light emitting structure. Fig. 4(b) shows the array arrangement of the light emitting structure 10 with leakage prevention function, as viewed from the backside of the light emitting structure 10 with leakage prevention function.

[0028] In the conventional array arrangement of light-emitting structures shown in FIG. 4(a), one pixel is composed of three subpixels each having an LED 4 (red LED, green LED, and blue LED) for each of RGB, and a light-emitting structure is provided for each subpixel. In addition, an opening 20 is provided between adjacent subpixels and between adjacent pixels. In FIG. 4(a), the electrode pattern is such that a plurality of LEDs 4 arranged in a line are lit collectively (all lit), and the opening 20 is also provided between the lines. No light-shielding layer 11 is provided between the anode electrode 2 and the cathode electrode 3, and a part of the back surface of the LED 4 is visible through the gap between the electrodes 2 and 3 from the back side of the light-emitting structure. For this reason, light irradiated from the back surface of the LED 4 toward the transparent substrate 1 leaks through the gap between the electrodes 2 and 3 to the back side.

[0029] In the array arrangement of this embodiment shown in Fig. 4(b), the light-emitting structure itself is the same as that in Fig. 4(a). That is, one pixel is composed of three subpixels each having an LED 4 for each of RGB, and an opening 20 is formed between adjacent subpixels, between adjacent pixels, and between lines. In the case of Fig. 4(b), a light-emitting structure 10 with leakage prevention function is provided for each subpixel. In each light-emitting structure 10 with leakage prevention function, a light-shielding layer 11 is disposed in a target area covering the gap between the anode electrode 2 and the cathode electrode 3, which makes it possible to significantly suppress light leakage to the back surface.

[0030] Although an example of a configuration with sub-pixels in which three RGB LEDs 4 are arranged in one pixel has been shown here, a configuration without sub-pixels in which one LED 4 is arranged in one pixel may also be used.

[0031] Here, in order to enhance the effect of preventing light leakage, the length of the target area where the light-shielding layer 11 is disposed in the direction connecting the anode electrode 2 and the cathode electrode 3 (L direction in the figure) may be equal to or greater than the distance between the electrodes 2 and 3. However, the upper limit of the length is the length at which the adjacent target areas do not overlap. In other words, the upper limit of the length is the length at which the light-shielding layers 11 adjacent to each other in the L direction in FIG. 4(b) do not overlap each other. Also, the width of the target area where the light-shielding layer 11 is disposed in the direction perpendicular to the direction connecting the anode electrode 2 and the cathode electrode 3 (W direction in the figure) may be equal to or greater than the narrower of the width of the electrodes 2 and 3 or the width of the LED 4. However, the upper limit of the width is the width at which the adjacent target areas do not overlap each other. In other words, the upper limit of the width is the width at which the light-shielding layers 11 adjacent to each other in the W direction in FIG. 4(b) do not overlap each other.

[0032] It should be noted that the length of the light-shielding layer 11 in the L direction may be set to the length that protrudes from the electrodes 2, 3 into the opening 20, and the width of the light-shielding layer 11 in the W direction may be set to the width that protrudes from the electrodes 2, 3 into the opening 20, but in that case, a part of the opening 20 will be shielded by the light-shielding layer 11, decreasing the aperture ratio of the pixel. Therefore, it is desirable to prevent the part of the light-shielding layer 11 that protrudes from the electrodes 2, 3 into the opening 20 from becoming too wide. Regardless of the length or width of the light-shielding layer 11, it is preferable that the target area for disposing the light-shielding layer 11 is an area that does not protrude from the electrodes 2, 3 into the opening 20.

[0033] Although Fig. 4 shows an electrode pattern in which a plurality of LEDs 4 arranged in a line are lit collectively, the light emitting structure 10 with leakage prevention function of this embodiment can be applied to other electrode patterns. For example, it can be applied to a case in which a plurality of LEDs 4 are arranged in a matrix as shown in Fig. 5. In the example of array arrangement shown in Fig. 5, the anode electrode 2 and the cathode electrode 3 protruding like branches from the electrodes 2A and 3A crossing each other vertically and horizontally are connected to the LED 4. In this case as well, a light shielding layer 11 is placed in the gap between the anode electrode 2 and the cathode electrode 3.

[0034] 1 shows a configuration in which the target area for disposing the light-shielding layer 11 includes an area that blocks the optical path and covers the gap between the electrodes 2 and 3 on the front side of the gap, but the light-shielding layer 11 may be located in any layer of the cross section of the light-emitting structure as long as the area includes an area that blocks the optical path. The light-emitting structure to which the light-shielding layer 11 is applied is not limited to the one shown in FIG. 6 shows several modified examples of a light-emitting structure with a leakage prevention function that includes the light-shielding layer 11.

[0035] Fig. 6(a) shows a configuration example of a light-emitting structure 10A with leakage prevention function in which a light-shielding layer 11 is arranged in a target area that blocks the gap between two electrode pads 6 connected to an anode electrode 2 and a cathode electrode 3 in a light-emitting structure in which the height of the electrode pads 6 is lower than that of the light-emitting structure 10 with leakage prevention function shown in Fig. 1 and the second insulating layer 9 is eliminated. In this configuration example as well, the target area in which the light-shielding layer 11 is arranged includes an area that blocks the optical path, and is an area that covers the gap between the electrodes 2 and 3 on the front side of the gap.

[0036] Fig. 6(b) shows a configuration example of a light-emitting structure 10B with a leakage prevention function in which a light-emitting structure in which the contact hole 5, electrode pad 6, and insulating layers 8 and 9 shown in the light-emitting structure 10 with a leakage prevention function in Fig. 1 are eliminated, and a conductive adhesive 7 is directly formed on the electrodes 2 and 3 to mount an LED 4, and a light-shielding layer 11 is disposed in a target area to close the gap between the anode electrode 2 and the cathode electrode 3. Note that in light-emitting structures similar to those in Fig. 1 and Fig. 6(a), a light-shielding layer 11 may be disposed in a target area to close the gap between the electrodes 2 and 3.

[0037] Fig. 6(c) shows a configuration example of a light-emitting structure 10C with a leakage prevention function, in which a light-shielding layer 11 is arranged on the back surface of the transparent substrate 1 in a light-emitting structure similar to that in Fig. 6(b). In this case, the target area in which the light-shielding layer 11 is arranged includes an area that blocks the optical path, and is an area that covers the gap between the electrodes 2 and 3 on the back side of the gap. Note that the light-shielding layer 11 may be arranged on the back surface of the transparent substrate 1 in a light-emitting structure similar to that in Fig. 1 or Fig. 6(a).

[0038] Fig. 6(d) shows a configuration example of a light-emitting structure 10D with a leakage prevention function, in which a light-shielding layer 11 is arranged on the back surface of the LED 4 in the same light-emitting structure as Fig. 6(b). Note that a light-shielding layer 11 may be arranged on the back surface of the LED 4 in the same light-emitting structure as Fig. 1 or Fig. 6(a).

[0039] As described above in detail, in this embodiment, in the light emitting structure of the transmissive LED display using the micro LED elements, the light shielding layer 11 is disposed in a target area including an area blocking the light path from a portion of the back surface of the LED 4 facing the gap between the electrodes 2 and 3 toward the transparent substrate 1. As a result, when the LED 4 is turned on, the light irradiated from the back surface of the LED 4 toward the transparent substrate 1 is blocked by the light shielding layer 11, so that it is possible to prevent the light irradiated by the LED 4 from leaking to the back surface of the display.

[0040] In the above embodiment, a configuration in which the light-shielding layer 11 is applied to a transmissive LED display using micro LED elements is described. However, the light-emitting structure with leakage prevention function of this embodiment can be applied to any transmissive display having a structure in which light emitted from a light source leaks through the gap between electrodes.

[0041] In addition, the above-mentioned embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited thereby. In other words, the present invention can be implemented in various forms without departing from the gist or main characteristics thereof. [Explanation of symbols]

[0042] 1 Transparent substrate 2 Anode electrode 3. Cathode Electrode 4 LED (light source) 10, 10A, 10B, 10C, 10D Light-emitting structure with leakage prevention function 11 Light blocking layer 20 Opening

Claims

1. A transmissive display comprising: a plurality of light sources disposed between a plurality of sets of electrodes arranged in an array on a transparent substrate; and a plurality of openings provided with no electrodes, so that light can be transmitted through the plurality of openings; A transmissive display characterized in that a light-shielding layer is disposed in a target area including an area that blocks an optical path from a portion of the back surface of the light source facing the gap between the electrodes toward the transparent substrate.

2. 2. The transmissive display according to claim 1, wherein the target area includes an area that blocks the optical path and covers the gap between the electrodes.

3. 3. The transmissive display according to claim 2, wherein the length of the target area in the direction connecting the electrodes is equal to or greater than the distance between the electrodes, and the length is such that the target area does not overlap with adjacent target areas.

4. The transmissive display according to claim 2, characterized in that the width of the target area in a direction perpendicular to the direction connecting the electrodes is equal to or greater than the narrower of the width of the electrode or the width of the light source, and does not overlap with adjacent target areas.

5. 2. The transmissive display according to claim 1, wherein the target area includes an area that blocks the optical path and is an area that closes the gap between the electrodes.

6. 2. The transmissive display according to claim 1, wherein the light-shielding layer has an optical density of 3 or more.

7. 7. The transmissive display according to claim 1, wherein a micro LED element is used as the light source.

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