Light-emitting device

Abstract

To provide a light-emitting device with improved luminous efficiency.SOLUTION: A light-emitting device includes an LED element provided on a substrate, a wall portion provided on the substrate around the LED element, and at least one reflector having a tapered shape narrowing toward the side opposite the substrate and provided between the LED element and the wall portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, micro LED (Light Emitting Diode) displays have been attracting 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 light-shielding partition walls. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-205417 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when an LED element is formed by stacking p-type and n-type semiconductors in the height direction, the light emitted from the LED element is mainly emitted from the side of the LED element. In the micro LED display device disclosed in the above Patent Document 1, a light-shielding partition is provided on the side of the LED element, making it difficult to effectively use the light emitted on the side of the LED element.

[0006] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a new and improved light-emitting device that can increase the light-emitting efficiency by more effectively utilizing the light emitted from the LED element. [Means for solving the problem]

[0007] In order to solve the above problems, according to one aspect of the present invention, there is provided a light emitting device comprising an LED element provided on a substrate, a wall portion provided on the substrate around the LED element, and at least one reflector portion having a tapered shape narrowing toward the side opposite the substrate and provided between the LED element and the wall portion. Effect of the Invention

[0008] As described above, according to the present invention, it is possible to more effectively utilize the light emitted from the LED element, thereby further increasing the luminous efficiency of the light emitting device. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a cross-sectional configuration of a light-emitting device according to one embodiment of the present invention. [Diagram 2] 2 is a schematic cross-sectional view showing a first planar configuration of the light emitting device according to the embodiment. FIG. [Diagram 3] 4 is a schematic cross-sectional view showing a second planar configuration of the light emitting device according to the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0011] <1. Cross-sectional configuration> First, a cross-sectional configuration of a light-emitting device according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the cross-sectional configuration of a light-emitting device 1 according to this embodiment. Fig. 1 shows the cross-sectional configuration of the light-emitting device 1 cut in a direction perpendicular to the display surface.

[0012] 1, the light emitting device 1 includes a substrate 100, an LED element 110, a reflecting 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 an RGB color model using a red pixel 10R, a green pixel 10G, and a blue pixel 10B.

[0013] When the red pixel 10R, the green pixel 10G, and the blue pixel 10B are not distinguished from one another, they are collectively referred to as pixels 10. Similarly, when the phosphors 140R, 140G, and 140B are not distinguished from one another, they are collectively referred to as phosphors 140.

[0014] The substrate 100 is a support for the pixels 10, and the pixels 10 are provided in an array on a main surface of the substrate 100. Although not shown, the substrate 100 is also provided with a drive circuit for individually driving each of the pixels 10, and a control circuit for controlling the drive of each of the pixels 10. 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 made of polyester, polyethersulfone, or the like.

[0015] 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.

[0016] The LED element 110 is composed of a pn junction in which a p-type semiconductor and an n-type semiconductor are joined, and emits light when a forward voltage is applied. Specifically, when a forward voltage is applied 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 injected electrons and holes exceed the forbidden band near the pn junction and recombine, and the LED element 110 can emit energy approximately equivalent to the band gap as light at the time of recombination. The LED element 110 may emit ultraviolet light with a wavelength of approximately 300 nm, for example. The ultraviolet light emitted from the LED element 110 is converted into red light, green light, or blue light by the phosphors 140R, 140G, and 140B.

[0017] The LED element 110 may be configured with a pn junction of a compound semiconductor such as InGaN, GaN, or AlGaN. The LED element 110 may also have a pn junction formed by stacking compound semiconductors in a direction perpendicular to the main surface of the substrate 100.

[0018] The wall portions 130 are provided on the main surface of the substrate 100 between the pixels 10, and extend in a wall-like manner in a direction perpendicular to the main surface of the substrate 100. The wall portions 130 are provided in a lattice shape between the pixels 10, and can separate the pixels 10 from one another. The wall portions 130 may be made of an organic resin, such as, for example, an epoxy resin, a (meth)acrylic resin, a polyurethane, a polyester, a polyimide, a polyolefin, or a polysiloxane. The wall portions 130 may also contain a black pigment to impart light blocking properties.

[0019] Moreover, the wall portion 130 is provided so as to extend to a position higher than the height of the LED element 110. With this, in the pixel 10, the phosphor 140 can be filled between the wall portions 130 so as to cover the LED element 110, and therefore 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.

[0020] The reflecting section 120 has a tapered shape that narrows 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 section 130. The reflecting section 120 can reflect light emitted in the side direction of the LED element 110 to the side opposite to the substrate 100 by having a surface made of metal or by having a surface and an interior made of a material having different refractive indexes. This allows the reflecting section 120 to allow more light emitted from the LED element 110 to be incident on the phosphor 140 without being absorbed by the substrate 100 and the wall section 130, thereby further improving the light emission efficiency of the pixel 10.

[0021] For example, the reflecting section 120 may be a tapered structure made of a metal material such as silver, copper, or aluminum. The reflecting section 120 may also be a tapered organic resin structure whose surface is coated with a metal material such as silver, copper, or aluminum. Furthermore, the reflecting section 120 may be a structure in which organic resins having different refractive indices are laminated between the inside and the surface.

[0022] 1, the reflecting portion 120 is provided on both sides of the LED element 110, but it is sufficient that at least one reflecting portion 120 is provided between the LED element 110 and the wall portion 130. However, preferably, the reflecting portion 120 may be provided so as to surround the LED element 110 in a planar manner on the main surface of the substrate 100, as described later. In this case, the reflecting portion 120 may be provided so as to surround the LED element 110 continuously or discretely.

[0023] The height of the reflecting portion 120 may be approximately the same as the height of the LED element 110. However, it is preferable that the height of the reflecting portion 120 is lower than the height of the LED element 110. This is because the reflecting portion 120 is provided at approximately the same height as the LED element 110, and most of the light emitted from the side direction of the LED element 110 can be reflected. In other words, it is not preferable to make the height of the reflecting portion 120 higher than the height of the LED element 110 because there is little merit in terms of cost. Specifically, even if the height of the reflecting portion 120 is made higher than the height of the LED element 110, the increase in the light emission efficiency of the pixel 10 is small relative to the increase in manufacturing cost, and the increase in the reflecting portion 120 reduces the amount of filling of the phosphor 140 between the wall portions 130, which is not preferable.

[0024] Note that the reflecting section 120 does not have to be tapered as long as it can reflect the light emitted from the side direction of the LED element 110 to the opposite side of the substrate 100. That is, the reflecting section 120 only needs to be provided with a side surface facing the LED element 110 inclined away from the LED element 110 toward the opposite side of the substrate 100. In such a case, the side surface of the reflecting section 120 not facing the LED element 110 may be inclined in any direction, or may be perpendicular to the main surface of the substrate 100 without being inclined.

[0025] The phosphor 140 is filled between the wall parts 130 so as to cover the LED element 110 and the reflector 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 material that emits red fluorescence by absorbing ultraviolet light, the phosphor 140G is a fluorescent material that emits green fluorescence by absorbing ultraviolet light, and the phosphor 140B is a fluorescent material that emits blue fluorescence by absorbing ultraviolet light. The phosphor 140 may be a known inorganic or organic fluorescent material. The phosphor 140 may also be a phosphorescent material, or may be a quantum dot that can control the wavelength of light emitted depending on the size.

[0026] The phosphor 140 and the upper portion of the wall portion 130 are sealed with 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.

[0027] According to the above configuration, the light emitting device 1 according to this embodiment can allow more light emitted from the LED element 110 to be incident on the phosphor 140, thereby improving the light emitting efficiency of the pixel 10. Therefore, the light emitting device 1 can improve the light emitting efficiency of the pixel 10 while effectively utilizing the space between the LED element 110 and the wall portion 130 by the reflector 120.

[0028] In the light emitting device 1, the wall section 130 that separates the pixels 10 and the reflecting section 120 that reflects the light emitted from the LED element 110 are configured separately. Therefore, the light emitting device 1 can separate the pixels 10 with more space-efficient and simple wall section 130, and therefore the amount of phosphor 140 filled between the wall section 130 can be increased. Also, the light emitting device 1 can efficiently reflect the light emitted from the LED element 110 to the phosphor 140 by the smaller reflecting section 120.

[0029] <2.Plane configuration> Next, the planar configuration of the light emitting device 1 according to this embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a schematic plan view showing a first planar configuration of the light emitting device 1 according to this embodiment. Fig. 3 is a schematic plan view showing a second planar configuration of the light emitting device 1 according to this embodiment.

[0030] 2 and 3, in the light emitting device 1, the pixels 10 are arranged in a matrix in a so-called Bayer array. Walls 130 are provided between the pixels 10, extending in a lattice pattern in vertical and horizontal directions perpendicular to each other. An LED element 110 having a rectangular planar shape is provided in each pixel 10.

[0031] (First Plane Configuration) 2, in the first planar configuration, the reflecting portion 120 is provided so as to surround the outer periphery of the LED element 110. Specifically, the reflecting portion 120 may be provided so as to continuously surround the outer periphery of the LED element 110 having a rectangular planar shape in a frame shape. By surrounding the entire periphery of the LED element 110, the reflecting portion 120 can reflect more of the light emitted from the side direction of the LED element 110 to the opposite side to the substrate 100 (i.e., the front direction in the paper plane of FIG. 2).

[0032] (Second Plane Configuration) As shown in FIG. 3, in the second planar configuration, the reflecting portions 120 are provided so as to extend opposite to each side of the LED element 110 and spaced apart from each other. Specifically, the reflecting portions 120 may be provided in a linear shape at four positions opposite to each side of the LED element 110 having a rectangular planar shape. The reflecting portions 120 are provided around the LED element 110 and spaced apart from each other, so that they can be formed in a simplified manufacturing process. Even in such a case, the reflecting portion 120 can sufficiently reflect the light emitted from the side direction of the LED element 110 to the opposite side of the substrate 100 (i.e., the front direction with respect to the paper surface of FIG. 3). In addition, the reflecting portions 120 are spaced apart from each other, so that the phosphor can be filled more uniformly between the LED element 110 and the wall portion 130. Therefore, according to the second planar configuration, the reflecting portion 120 can improve the luminous efficiency of the phosphor 140.

[0033] Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0034] Although the light emitting device 1 according to the present embodiment has been described above as a full-color display device based on the RGB color model, the present invention is not limited to such an example. The light emitting device 1 according to the present embodiment may be a light emitting device such as a lamp, light source, or lighting device that includes a single LED element 110, a wall portion 130, and a reflector 120, without the LED elements 110 being arranged as pixels 10. [Explanation of symbols]

[0035] 1...light-emitting device, 10, 10R, 10G, 10B...pixels, 100...substrate, 110...LED element, 120...reflection portion, 130...wall portion, 140, 140R, 140G, 140B...phosphor

Claims

1. An LED element provided on a substrate; A wall portion provided on the substrate around the LED element; At least one reflecting portion having a tapered shape narrowing toward an opposite side to the substrate and provided between the LED element and the wall portion; A light emitting device comprising:

2. The light emitting device according to claim 1 , wherein the reflecting portions are provided on both sides of the LED element.

3. The light emitting device according to claim 2 , wherein the reflector is provided so as to surround the entire periphery of the LED element.

4. 4. The light emitting device according to claim 1, wherein the height of the reflecting portion is smaller than the height of the LED element.

5. 4. The light emitting device according to claim 1, wherein at least a surface of the reflecting portion is made of a metal.

6. 4. The light emitting device according to claim 1, wherein a space separated from said LED element by said wall portion is filled with a phosphor that emits fluorescence when exposed to light emitted from said LED element.

7. The LED elements are provided in a plurality for each pixel arranged on the substrate, 4. The light emitting device according to claim 1, wherein the wall portions separate the LED elements from each other for each pixel.

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