Light emitting device

Abstract

The invention provides a light-emitting device with further improved light-emitting efficiency. A light emitting device includes: an LED element disposed on a substrate; a wall portion provided on the substrate around the LED element; and at least one or more reflecting parts which have a tapered shape that tapers toward the side opposite to the substrate, and which are provided between the LED element and the wall part.

Description

Technical Field

[0001] The invention relates to a light emitting device. Background Art

[0002] In recent years, micro-light emitting diode (LED) displays have attracted much attention as a new display technology. Micro-LED displays are display devices that use miniaturized LED elements as pixels and arrange them in an array on the display surface. Micro-LED displays can display images with high contrast and high response speed by individually controlling the light emission of the LED elements of each pixel.

[0003] For example, Patent Document 1 listed below discloses a micro LED display device in which LED elements arranged on a display substrate are separated from each other by partition walls having a light-shielding property.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-205417 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] However, when a p-type semiconductor and an n-type semiconductor are stacked in the height direction to form an LED element, light emitted from the LED element is mainly emitted from the side direction of the LED element. In the micro LED display device disclosed in Patent Document 1, a light-shielding partition wall is provided in the side direction of the LED element, so it is difficult to effectively use the light emitted in the side direction of the LED element.

[0009] Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a novel and improved light-emitting device capable of further improving the light-emitting efficiency by more effectively utilizing the light emitted from an LED element.

[0010] [Technical means to solve the problem]

[0011] In order to solve the above-mentioned problem, according to a certain aspect of the present invention, there is provided a light-emitting device, which comprises: an LED element, which is arranged on a substrate; a wall portion, which is arranged on the substrate around the LED element; and at least one reflecting portion, which has a conical shape that tapers toward a side opposite to the substrate and is arranged between the LED element and the wall portion.

[0012] [Effects of the Invention]

[0013] As described above, according to the present invention, the light emitted from the LED element can be more effectively used, thereby further improving the light emission efficiency of the light emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic cross-sectional view showing the cross-sectional structure of a light emitting device according to one embodiment of the present invention.

[0015] Figure 2 It is a schematic cross-sectional view showing a first planar structure of the light emitting device of this embodiment.

[0016] Figure 3 It is a schematic cross-sectional view showing a second planar structure of the light-emitting device of this embodiment.

[0017] [Explanation of Symbols]

[0018] 1: Light-emitting device

[0019] 10, 10R, 10G, 10B: pixels

[0020] 100: Substrate

[0021] 110: LED components

[0022] 120: Reflection part

[0023] 130: Wall

[0024] 140, 140R, 140G, 140B: Phosphor DETAILED DESCRIPTION

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this specification and the accompanying drawings, components having substantially the same functional structure are denoted by the same reference numerals, and repeated description is omitted.

[0026] <1. Cross-sectional structure>

[0027] First, refer to Figure 1 A cross-sectional structure of a light emitting device according to one embodiment of the present invention will be described. Figure 1 is a schematic cross-sectional view showing the cross-sectional structure of the light emitting device 1 of this embodiment. Figure 1 The structure of a cross section of the light emitting device 1 cut in a direction perpendicular to the display surface is shown.

[0028] like Figure 1As shown, the light emitting device 1 includes: a substrate 100, an LED element 110, a reflective portion 120, a wall portion 130, and phosphors 140R, 140G, and 140B. For example, the light emitting device 1 is a full-color display device based on a red green blue (RGB) color model using a red pixel 10R, a green pixel 10G, and a blue pixel 10B.

[0029] In addition, when the red pixel 10R, the green pixel 10G, and the blue pixel 10B are not distinguished from each other, they are also collectively referred to as pixels 10. Similarly, when the phosphors 140R, the phosphors 140G, and the phosphors 140B are not distinguished from each other, they are collectively referred to as phosphors 140.

[0030] The substrate 100 is a support body for the pixels 10, and the pixels 10 are arranged in an array on the main surface of the substrate 100. In addition, although not shown in the figure, a driving circuit for driving each of the pixels 10 individually and a control circuit for controlling the driving of each of the pixels 10 are arranged on the substrate 100. The substrate 100 may be, for example, a glass substrate, a glass epoxy substrate, an epoxy substrate, a polyimide substrate, or a (meth) acrylic substrate, or may be a flexible substrate including polyester or polyethersulfone.

[0031] The LED element 110 is provided for each pixel 10 arranged in an array on the main surface of the substrate 100. For example, the LED element 110 may be provided for each pixel 10 arranged in a matrix.

[0032] The LED element 110 includes a pn junction formed by a p-type semiconductor and an n-type semiconductor, and emits light by applying a forward voltage. Specifically, by applying a forward voltage to the electrodes of the LED element 110, electrons and holes are injected from the electrodes into the LED element 110. As a result, the LED element 110 is recombined by the injected electrons and holes crossing the forbidden band near the pn junction, and energy roughly equivalent to the band gap can be emitted as light during the recombination. The LED element 110 can emit ultraviolet light with a wavelength of about 300nm, for example. The ultraviolet light emitted from the LED element 110 is converted into red light, green light, or blue light by the phosphor 140R, the phosphor 140G, and the phosphor 140B.

[0033] The LED element 110 may include a pn junction of a compound semiconductor such as InGaN, GaN, or AlGaN. Alternatively, the LED element 110 may form a pn junction by stacking compound semiconductors in a direction perpendicular to the main surface of the substrate 100 .

[0034] The wall portion 130 is provided on the main surface of the substrate 100 between the pixels 10, and extends in a wall shape in a direction perpendicular to the main surface of the substrate 100. The wall portion 130 can separate the pixels 10 from each other by being provided in a lattice shape between the pixels 10. The wall portion 130 can include, for example, an organic resin such as epoxy resin, (meth) acrylic resin, polyurethane, polyester, polyimide, polyolefin, or polysiloxane. In addition, the wall portion 130 can also contain a black pigment in order to impart light-shielding properties.

[0035] In addition, the wall portion 130 is provided to extend to a position higher than the height of the LED element 110. Thus, the pixel 10 can fill the phosphor 140 between the wall portions 130 so as to cover the LED element 110, and thus the ultraviolet light emitted from the LED element 110 can be efficiently converted into red light, green light, or blue light by the phosphor 140.

[0036] The reflective portion 120 has a tapered shape that tapers toward the side opposite to the substrate 100, and is provided on the main surface of the substrate 100 between the LED element 110 and the wall portion 130. The surface of the reflective portion 120 includes a metal, or includes a material having different refractive indexes on the surface and inside, thereby reflecting light emitted in the side direction of the LED element 110 toward the side opposite to the substrate 100. Thus, the reflective portion 120 does not allow the substrate 100 and the wall portion 130 to absorb the light emitted from the LED element 110, but allows more light to enter the fluorescent body 140, thereby further improving the light emission efficiency of the pixel 10.

[0037] For example, the reflector 120 may be a conical structure including a metal material such as silver, copper or aluminum. In addition, the reflector 120 may be a conical structure of an organic resin coated with a metal material such as silver, copper or aluminum. Furthermore, the reflector 120 may be a structure in which organic resins with different refractive indices are stacked inside and on the surface.

[0038] exist Figure 1 In the embodiment, the reflective portion 120 is disposed on both sides in a manner of sandwiching the LED element 110, but at least one reflective portion 120 only needs to be disposed between the LED element 110 and the wall portion 130. It is preferred that the reflective portion 120 can also be disposed in a manner of planarly surrounding the LED element 110 on the main surface of the substrate 100 as described later. In this case, the reflective portion 120 can be disposed in a manner of continuously surrounding the LED element 110 or in a manner of discretely surrounding the LED element 110.

[0039] The height of the reflecting portion 120 may be substantially the same as the height of the LED element 110. The height of the reflecting portion 120 is preferably lower than the height of the LED element 110. The reason for this is that by setting the reflecting portion 120 at substantially the same height as the LED element 110, most of the light emitted from the side direction of the LED element 110 can be reflected. That is, making the height of the reflecting portion 120 higher than the height of the LED element 110 is not preferred because it has few cost advantages. Specifically, even if the height of the reflecting portion 120 is higher than the height of the LED element 110, the increase in the luminous efficiency of the pixel 10 is small relative to the increase in manufacturing cost, and the reflecting portion 120 becomes larger, thereby reducing the amount of phosphor 140 filled between the wall portions 130, which is not preferred.

[0040] Furthermore, the reflective portion 120 may not be provided in a tapered shape if it can reflect light emitted from the side direction of the LED element 110 toward the side opposite to the substrate 100. That is, the reflective portion 120 may be provided in an inclined manner so that the side facing the LED element 110 is away from the LED element 110 toward the side opposite to the substrate 100. In the above case, the side of the reflective portion 120 not facing the LED element 110 may be inclined in any direction, or may be not inclined but perpendicular to the main surface of the substrate 100.

[0041] The phosphor 140 is filled between the wall portions 130 in a manner covering the LED element 110 and the reflective portion 120, and converts the light emitted from the LED element 110 into red light, green light, or blue light. For example, the phosphor 140R is a fluorescent substance that emits red fluorescence by absorbing ultraviolet rays, the phosphor 140G is a fluorescent substance that emits green fluorescence by absorbing ultraviolet rays, and the phosphor 140B is a fluorescent substance that emits blue fluorescence by absorbing ultraviolet rays. The phosphor 140 can be a well-known inorganic or organic fluorescent substance. In addition, the phosphor 140 can be a phosphorescent substance or a quantum dot that can control the wavelength of the emitted light according to the size.

[0042] The upper part of the fluorescent body 140 and the wall portion 130 is sealed by a transparent film or a transparent substrate (not shown). The red light, green light, and blue light emitted from each pixel 10 are transmitted through the transparent film or the transparent substrate and emitted to the outside.

[0043] According to the above structure, the light emitting device 1 of this embodiment can make more light emitted from the LED element 110 enter the fluorescent body 140, thereby further improving the light emitting efficiency of the pixel 10. Therefore, the light emitting device 1 can effectively utilize the space between the LED element 110 and the wall portion 130 through the reflective portion 120, while further improving the light emitting efficiency of the pixel 10.

[0044] In the light emitting device 1, the wall portion 130 for partitioning the pixels 10 and the reflective portion 120 for reflecting the light emitted from the LED element 110 are separately formed. Therefore, the light emitting device 1 can partition the pixels 10 with the wall portion 130 which is more space efficient and simple, so the amount of the phosphor 140 filled between the wall portions 130 can be increased. In addition, the light emitting device 1 can efficiently reflect the light emitted from the LED element 110 to the phosphor 140 by using the smaller reflective portion 120.

[0045] <2. Plane structure>

[0046] Next, refer to Figure 2 as well as Figure 3 , the planar structure of the light emitting device 1 of this embodiment is described. Figure 2 1 is a schematic plan view showing a first plan structure of the light emitting device 1 according to the present embodiment. Figure 3 1 is a schematic plan view showing a second planar structure of the light emitting device 1 according to the present embodiment.

[0047] like Figure 2 as well as Figure 3 As shown, in the light emitting device 1, pixels 10 are arranged in a matrix in a so-called Bayer arrangement. Walls 130 are arranged in a grid pattern in mutually orthogonal longitudinal and lateral directions. In each pixel 10, a rectangular LED element 110 is arranged.

[0048] (First Plane Structure)

[0049] like Figure 2 As shown in FIG. 1 , in the first planar structure, the reflective portion 120 is provided in a manner of surrounding the outer periphery of the LED element 110. Specifically, the reflective portion 120 may be provided in a manner of continuously surrounding the outer periphery of the rectangular planar LED element 110 in a frame shape. By surrounding the entire periphery of the LED element 110 across one circumference, the reflective portion 120 may allow more light emitted from the side direction of the LED element 110 to be directed toward the side opposite to the substrate 100 (i.e., relative to the substrate 100). Figure 2 The paper surface is reflected in the front direction).

[0050] (Second Plane Structure)

[0051] like Figure 3As shown, in the second planar structure, the reflective portions 120 are respectively arranged to extend in a manner facing each side of the LED element 110 and are separated from each other. Specifically, the reflective portions 120 can be respectively arranged in a straight line shape at four positions facing each side of the rectangular planar shape of the LED element 110. The reflective portions 120 can be formed by a simplified manufacturing process by being arranged in a manner separated from each other around the LED element 110. Even in this case, the reflective portions 120 can allow the light emitted from the side direction of the LED element 110 to be fully directed to the side opposite to the substrate 100 (i.e., relative to the substrate 100). Figure 3 In addition, the reflective parts 120 can be separated from each other to make the phosphor more uniformly filled between the LED element 110 and the wall part 130. Therefore, according to the second planar structure, the reflective part 120 can improve the luminous efficiency of the phosphor 140.

[0052] The preferred embodiments of the present invention are described in detail with reference to the accompanying drawings, but the present invention is not limited to the examples described above. It is obvious that anyone with ordinary knowledge in the technical field to which the present invention belongs can think of various variations or modifications within the scope of the technical ideas described in the claims, and it should be understood that these also belong to the technical scope of the present invention.

[0053] In the above description, the light emitting device 1 of the present embodiment is described as a full-color display device based on the RGB color model, but the present invention is not limited to the above example. The light emitting device 1 of the present embodiment may also be a light emitting device such as a lamp, a light source, or a lighting device in which the LED elements 110 are not arranged as pixels 10, but include individual LED elements 110, a wall portion 130, and a reflective portion 120.

Claims

1. A light emitting device, comprising: The light emitting diode element is disposed on the substrate; a wall portion, disposed on the substrate around the light emitting diode element; as well as At least one reflecting portion has a tapered shape that tapers toward a side opposite to the substrate, and is provided between the light emitting diode element and the wall portion.

2. The light emitting device according to claim 1, wherein: The reflecting parts are respectively arranged on both sides in a manner of sandwiching the light emitting diode element.

3. The light emitting device according to claim 2, wherein: The reflecting portion is provided so as to surround the entire circumference of the light emitting diode element.

4. The light emitting device according to any one of claims 1 to 3, wherein: The height of the reflecting portion is lower than the height of the light emitting diode element.

5. The light emitting device according to any one of claims 1 to 3, wherein: In the reflecting portion, at least a surface thereof includes metal.

6. The light emitting device according to any one of claims 1 to 3, wherein: A fluorescent material is filled in a space partitioned by the wall around the light emitting diode element, and the fluorescent material emits fluorescence due to the light emitted from the light emitting diode element.

7. The light emitting device according to any one of claims 1 to 3, wherein: The light emitting diode element is provided in plurality for each pixel arranged on the substrate. The wall portion separates the light emitting diode elements from each other for each of the pixels.

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