KR20080061489A - Light source for backlight and backlight and liquid crystal display having the same - Google Patents

Abstract

A light source for backlight, a backlight and an LCD having the same are provided to apply a material layer having a refractive index, bigger than a refractive index of a GaN layer, onto an LED device including the GaN layer, thereby improving efficiency of an external proton of the LED device. Plural LED(Light Emitting Diode) devices(200) are mounted on a substrate(100). A transparent electrode layer(310) is prepared on the plural LED devices. A full-reflection preventing layer(400) is interposed between at least the plural LED devices and the transparent electrode layer. A transparent substrate is prepared on the transparent electrode layer. A buffer layer(500) is prepared on the substrate of an area among the plural LED devices. The LED device comprises a P type semiconductor layer(210), an active layer(220) and an N type semiconductor layer(230). The active layer is manufactured by using a GaN film.

Description

LIGHT SOURCE FOR BACKLIGHT AND BACKLIGHT AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

1 is an exploded perspective view of a backlight light source according to an embodiment of the present invention, Figure 2 is a cross-sectional conceptual view of a backlight light source according to an embodiment.

3 is a plan view of the LED device according to an embodiment.

4 is a conceptual diagram illustrating a texturing pattern of an LED device according to an embodiment.

5 is a plan conceptual view of an LED device according to a modification of the embodiment;

6 is a cross-sectional conceptual view of a light source for a backlight according to an embodiment.

7 and 8 are cross-sectional conceptual view of a light source for a backlight according to a modification of the embodiment.

9 is an exploded perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment.

<Explanation of symbols for the main parts of the drawings>

100: substrate 200: LED element

300: transparent cover layer 310: transparent electrode layer

400: total reflection prevention film 500: buffer layer

600: backlight

The present invention relates to a backlight light source and a backlight, and a liquid crystal display including the same. A backlight light source and a backlight capable of improving light extraction efficiency of a flexible LED including a plurality of LED elements and a liquid crystal display including the same. It is about.

Since the liquid crystal display does not emit light by itself, its sharpness is reduced in a dark place. Therefore, the liquid crystal display device has a light source such as a backlight. Conventionally, a cold cathode fluorescent lamp (CCFL) is used as a light source, but the use of LED packages capable of high life, low power consumption, light weight, and thickness has recently increased.

However, the LED device in the LED package has a disadvantage of low light extraction efficiency. That is, only about 20 to 40% of the amount of light generated inside the LED device has been emitted to the outside of the LED device. This is because some of the light generated inside the LED device is not totally reflected inside the LED device and is emitted. In addition, when manufacturing an LED by packaging an LED device, a problem arises that the light extraction efficiency of the LED is further lowered by the light-transmitting molding part provided on the LED device.

Accordingly, the present invention has been made to solve the above problems, and a light transmitting material having a refractive index greater than the refractive index of the LED device is disposed on the LED device, or between the LED device and the transparent conductive film provided thereon, Provides a backlight light source and backlight that can improve the light extraction efficiency of the LED device by reducing the total internal reflection by reducing the critical angle of the interface of the LED device by disposing a transparent material having a refractive index between the transparent conductive film and a liquid crystal display device including the same It is for that purpose.

A substrate according to the present invention, a plurality of LED elements mounted on the substrate, a transparent electrode layer provided on the plurality of LED elements, a total anti-reflection film provided between at least the plurality of LED elements and the transparent electrode layer, and on the transparent electrode layer It provides a light source for a backlight comprising a transparent substrate provided in.

It is preferable to further include a buffer layer provided on the substrate in the region between the plurality of LED elements.

As the total reflection prevention film, it is effective to use a material film having a refractive index larger than that of the semiconductor layer of the LED device. Of course, the total reflection prevention film has a refractive index smaller than the refractive index of the semiconductor layer of the LED element, it is possible to use a material film having a refractive index larger than the transparent electrode layer.

It is effective to provide a texturing pattern on the LED element surface in contact with the total reflection prevention film. The texturing pattern may include a pyramid-shaped protrusion, and the total reflection prevention layer may fill at least a portion of an area between the protrusions or may be provided along the texturing pattern.

The LED element preferably includes a P-type semiconductor layer connected to the substrate, an N-type semiconductor layer connected to the total reflection prevention film, and an active layer provided between the P-type semiconductor layer and the N-type semiconductor layer.

Preferably, the N-type semiconductor layer uses a GaN film, and the total reflection prevention film uses TiO ₂ . The N-type semiconductor layer may use a GaN film, the transparent electrode layer may use ITO, and the total reflection prevention film may use ZnO ₂ .

It is effective that the substrate is a flexible substrate.

In addition, mounting a plurality of LED elements on the substrate according to the present invention, forming a buffer layer on the substrate in the region between the LED element, forming a total anti-reflection film on at least the LED element, and It provides a method of manufacturing a light source for a backlight comprising the step of forming a transparent electrode layer on the total reflection prevention film and attaching a transparent substrate on the transparent electrode layer.

It is preferable to use a material film having a refractive index larger than that of the semiconductor layer of the LED device as the total reflection prevention film, or a material film having a refractive index smaller than that of the semiconductor layer of the LED device and having a refractive index larger than that of the transparent electrode layer. Do.

In addition, there is provided a substrate according to the present invention, an LED device having an N-type semiconductor layer and a P-type semiconductor layer and mounted such that the P-type semiconductor layer is in contact with the substrate, and a material having a higher refractive index than the N-type semiconductor layer. And a total reflection prevention film provided on the N-type semiconductor layer of the LED device, a transparent electrode layer provided on the total reflection prevention film, and a cover layer provided on the transparent electrode layer.

In addition, a LED device comprising a substrate according to the present invention, an N-type semiconductor layer and a P-type semiconductor layer, the P-type semiconductor layer is mounted so as to contact the substrate, a transparent electrode layer provided on the LED element, and It provides a light source for backlight having a refractive index between the refractive index of the N-type semiconductor layer and the refractive index of the transparent electrode layer, a total reflection prevention film provided between the N-type semiconductor layer and the transparent electrode layer and a cover layer provided on the transparent electrode layer. .

A light source for emitting light according to the present invention, an optical sheet provided on the light source, and a housing member for accommodating the backlight light source and the optical sheet, the backlight light source includes a substrate and the substrate. A backlight including a plurality of LED elements mounted on the substrate, a transparent electrode layer provided on the plurality of LED elements, a total reflection prevention film provided between at least the plurality of LED elements and the transparent electrode layer, and a transparent substrate provided on the transparent electrode layer. to provide.

Here, the total reflection prevention film is a material film having a refractive index larger than the refractive index of the semiconductor layer of the LED device, or a material film having a refractive index smaller than the refractive index of the semiconductor layer of the LED device, and having a refractive index larger than the transparent electrode layer. It is preferable.

A liquid crystal display panel for displaying an image according to the present invention, and a backlight for irradiating light to the liquid crystal display panel, the backlight includes a substrate, a plurality of LED elements mounted on the substrate, and the plurality of LED elements. Provided is a liquid crystal display including a transparent electrode layer provided thereon, a total reflection prevention film provided between at least the plurality of LED elements and the transparent electrode layer, and a transparent substrate provided on the transparent electrode layer.

As the total reflection prevention film, it is effective to use a material film having a refractive index greater than the refractive index of the semiconductor layer of the LED device, or to use a material film having a refractive index smaller than the refractive index of the semiconductor layer of the LED device and having a refractive index larger than that of the transparent electrode layer. to be.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you.

1 is an exploded perspective view of a backlight light source according to an embodiment of the present invention, Figure 2 is a cross-sectional conceptual view of a backlight light source according to an embodiment.

3 is a schematic conceptual view of an LED device according to an embodiment, and FIG. 4 is a conceptual view illustrating a texturing pattern of the LED device according to an embodiment. 5 is a schematic plan view of an LED device according to a modified example of the embodiment.

6 is a cross-sectional conceptual view of a backlight light source according to an embodiment, and FIGS. 7 and 8 are cross-sectional conceptual views of a backlight light source according to a modified example of the embodiment.

1 to 8, a backlight light source according to the present embodiment includes a substrate 100, a plurality of LED elements 200 mounted on the substrate 100 and having a texturing pattern 231. The transparent cover layer 300 provided on the LED device 200 and including the transparent electrode layer 310, and the total reflection prevention film 400 provided between the LED device 200 and the transparent cover layer 300 are provided. The apparatus further includes a buffer layer 500 provided on the sidewall surface of the LED device 200.

The substrate 100 uses an insulating or conductive substrate having flexibility. That is, the substrate 100 may be a polymer substrate made of a polymer material or a metal substrate made of a thin metal thin film. The backlight light source according to the present embodiment may have a flexible characteristic. Of course, the present invention is not limited thereto, and a printed circuit board may be used as the substrate 100. 6, a conductive reflective film 150 may be formed on the substrate 100. The conductive reflective film may reflect the light irradiated from the LED device 200 toward the substrate 100 in the front direction, and may supply power to the plurality of LED devices 200. In addition, conductive wires (not shown) for supplying power to the LED device 200 may be formed above or below the substrate 100, and power input pads receiving power from the outside are provided at both ends of the conductive wires. It may be arranged. In the case of using a flexible conductive substrate as the substrate 100, power may be directly supplied to the LED device 200 through the substrate 100, an insulating layer is formed on the substrate 100, and wiring is performed on the substrate 100. By forming a power supply may be supplied to the LED device 200 via a wiring. In addition, the wiring of the substrate 100 and the conductive reflective film 150 may be formed through a printing method such as screen printing.

A plurality of LED elements 200 are mounted on the substrate 100 having the above-described flexible characteristics. A buffer layer 500 is formed in the sidewall surface region of the mounted LED device 200. At this time, the buffer layer protects the LED device and prevents unwanted electrical connection of the plurality of LED devices. As the buffer layer 500, it is preferable to use a light-transmitting insulating film. The buffer layer 500 is formed by mounting a plurality of LED elements 200 on the substrate 100 and then filling a region between the plurality of LED elements 200 with a light-transmitting insulating layer.

As shown in FIGS. 2 and 6, the LED device 200 includes a P-type semiconductor layer 210, an active layer 220 provided on the P-type semiconductor layer 210, and N provided on the active layer 220. Type semiconductor layer 230. In this case, the P-type semiconductor layer 210, the N-type semiconductor layer 230, and the active layer 220 may be manufactured using a gallium nitride based thin film (eg, a GaN film). Here, the active layer 220 is preferably manufactured in a quantum well structure. Of course, the present invention is not limited thereto, and various structures for improving the internal quantum efficiency of the LED device 200 may be applied. Here, the internal quantum efficiency refers to the efficiency of light generated by combining electrons and holes in the active layer 220. That is, the internal quantum efficiency indicates how many bonds emit light by combining the amount of electrons and holes in the active layer 220 to 100. Each of the plurality of LED elements 200 mounted on the substrate 100 may be connected in series or in parallel. In addition, a plurality of LED element groups connected in series may be connected in parallel, respectively, or a plurality of LED element groups connected in parallel may be connected in series. The LED device 200 may use an LED device that emits white light. Of course, the present invention is not limited thereto, and an LED device emitting red light, green light, and blue light may be used.

The buffer layer 500 may be provided in the sidewall surface region of the active layer 220 and the P-type semiconductor layer 210 of the LED device 200.

As shown in FIGS. 3 and 5, an N-type electrode 240 is formed on the N-type semiconductor layer 230. Of course, although not shown, a P-type electrode may be formed under the P-type semiconductor layer 210.

As shown in the figure, the N-type semiconductor layer 230 includes a texturing pattern 231. The texturing pattern 231 includes a protrusion in which a portion of the N-type semiconductor layer 230 protrudes in a pyramid shape. That is, as shown in FIG. 4, the texturing pattern 230 includes protrusions having a triangular pyramid shape or a rectangular pyramid shape. The texturing pattern 231 may be disposed in the form of a dot, or may be arranged in a line shape, as shown in FIG. 5. It is preferable to form a texturing pattern 231 having a protrusion projecting in the form of a pyride and a recess removed in the form of a pyramid by etching a portion of the N-type semiconductor layer 230 through a texturing process. Of course, the present invention is not limited thereto, and the texturing pattern 231 may be manufactured by forming a pyramid-shaped nanopattern (projection) on the N-type semiconductor layer 230 through a texturing process. The texturing pattern 231 may be provided on the P-type semiconductor layer 210.

 As such, by forming the texturing pattern 231 on the N-type semiconductor layer 230, the amount of light generated by the active layer 220 and transmitted through the N-type semiconductor layer 230 may be increased. That is, conventionally, the interface between the N-type semiconductor layer 230 and the transparent electrode layer 310 provided on the upper surface is manufactured in a parallel shape, the light totally reflected at the interface is increased to the outside of the LED device 200 There has been a problem of reducing the amount of light emitted (ie external quantum efficiency). However, as described above, the texturing pattern 231 is formed on the N-type semiconductor layer 230 to deform the interface shape between the N-type semiconductor layer 230 and the transparent electrode layer 310 into a zigzag shape, thereby reducing the amount of light totally reflected at the interface. Can be reduced. As a result, the amount of light emitted to the outside of the LED device 200 can be increased. Here, the external quantum efficiency refers to the light extraction efficiency described in the conventional problem, and refers to the amount of light emitted to the outside of the LED device 200 among the light generated by the LED device 200.

In this embodiment, the total reflection prevention film 400 may be further formed between the N-type semiconductor layer 230 and the transparent electrode layer 310 to further improve the external quantum efficiency. Total reflection occurs at the interface between two materials with different refractive indices. In other words, total reflection is a phenomenon in which light is advanced from a medium having a large refractive index to a medium having a small refractive index, and is reflected at an interface between two media when the incident angle of light has an angle greater than a critical angle. Due to this phenomenon, some of the light generated in the active layer 220 of the LED device 200 cannot be emitted to the outside through the N-type semiconductor layer 230 and is totally reflected to be lost in the LED device 200, thereby causing the LED device 200 to be lost. Decreases the external quantum efficiency.

In this embodiment, in order to reduce the total reflection, a material having a refractive index greater than that of the N-type semiconductor layer 230 is used as the total reflection prevention film 400 or a transparent electrode layer smaller than the refractive index of the N-type semiconductor layer 230 ( A material having a refractive index greater than that of 310 is used. Using a material having a refractive index larger than that of the N-type semiconductor layer 230 as the total reflection prevention film 400, a medium having a small refractive index (N-type semiconductor layer 230) to a medium having a high refractive index (total reflection prevention film 400). It allows light to travel and suppresses total internal reflection. In addition, two media having a large difference in refractive index using a material having a refractive index smaller than the refractive index of the N-type semiconductor layer 230 and larger than the refractive index of the transparent electrode layer 310 as the total reflection prevention film 400 (the N-type semiconductor layer 230). Since the buffer material is inserted between the and the transparent electrode layer 310, the total reflection may be reduced by reducing the critical angle by reducing the difference in refractive index between the layers.

In addition, since the total reflection prevention film 400 is located in the light output direction of the LED device 200, it is preferable to have a light transmissive property, and because it is provided under the transparent electrode layer 310, it is preferable to have conductivity. The refractive index of the GaN film used as the N-type semiconductor layer 230 is about 2.3. Thus, the total reflection prevention film 400 uses a material whose refractive index is greater than 2.3. In the present embodiment, it is preferable to use TiO ₂ having a refractive index of 2.7 as the total reflection prevention film 400. In addition, when ITO having a refractive index of 1.7 is used as the transparent electrode layer 310, the total reflection prevention film uses a material having a refractive index larger than 1.7 and smaller than 2.3. In this embodiment, it is preferable to use ZnO ₂ having a refractive index of 2.0 as the total reflection prevention film 400.

First, when TiO ₂ is used as the total reflection prevention film 400, the light generated in the active layer 220 of the LED device 200 proceeds into the total reflection prevention film 400 through the N-type semiconductor layer 230. At this time, as described above, since the light proceeds from the low refractive index medium to the high refractive index medium between the N-type semiconductor layer 230 and the total reflection prevention film 400, total reflection does not occur. Light travels from the high refractive index medium to the low refractive index medium between the total anti-reflection film 400 and the transparent electrode layer 310, and the total internal reflection is generated at the interface between the total anti-reflection film 400 and the transparent electrode layer 310 because the difference in refractive index of each medium is large. Can be. As such, when total reflection occurs at the boundary between the total anti-reflection film 400 and the transparent electrode layer 310, the totally reflected light does not return to the inside of the LED device 200, but rather into the total anti-reflection film 400, which is a high refractive index medium. Total reflection. That is, the total reflection prevention film 400 plays a role of an optical waveguide and can diffuse light widely.

In addition, when ZnO ₂ is used as the total reflection prevention film 400, the luminous efficiency may be improved by reducing the amount of light totally reflected back to the LED device 200 by changing the critical angle.

 For example, when the refractive index of the N-type semiconductor layer 230 is 2.5 and the refractive index of the transparent electrode layer 310 provided on the LED device 200 is 1.7, the N-type semiconductor layer according to Snell's law When the angle of light incident on the interface between the 230 and the transparent electrode layer 310 (the incident angle of the light) exceeds 42.84 degrees (about 43 degrees), the total reflection is performed at the interface between the N-type semiconductor layer 230 and the transparent electrode layer 310. do. Therefore, when the N-type semiconductor layer 230 and the transparent electrode layer 310 are in contact with each other, the critical angle thereof is 43 degrees. That is, only the light within 43 degrees exits the LED element.

However, ZnO ₂ is positioned as the total reflection prevention film 400 between the N-type semiconductor layer 230 and the transparent electrode layer 310 as follows. According to Snell's law, the critical angle between the N-type semiconductor layer 230 and the total reflection prevention film 400 is 53 degrees. Therefore, the light within 53 degrees can exit the LED device 200, thereby increasing the amount of light that can be output compared to the existing 43 degrees. And, according to Snell's law, the critical angle between the total reflection prevention film 400 and the transparent electrode layer 310 is 58 degrees. As such, the total reflection prevention film 400 using ZnO ₂ may be placed between the N-type semiconductor layer 230 and the transparent electrode layer 310 to have a large critical angle, thereby increasing the amount of light emitted from the LED device 200. .

As shown in FIG. 6, the total reflection prevention film 400 is formed along a step of the texturing pattern 231 of the N-type semiconductor layer 230. Of course, as shown in FIG. 7, the region between the texturing patterns 231 of the N-type semiconductor layer 230 may be completely filled with the total reflection prevention film 400, and as shown in FIG. 8, the N may be completely covered with the total reflection prevention film 400. A portion of the region between the texturing patterns 231 of the type semiconductor layer 230 may be buried. In this case, it is preferable to form the total reflection prevention film 400 so that 50% of the height of the texturing pattern is embedded.

The total reflection prevention film 400 is preferably formed on the N-type semiconductor layer 230 through a sputtering method or a coating method. In the above description, the texturing pattern 231 is provided on the N-type semiconductor layer 230 of the LED device 200 in which the total reflection prevention film 400 is provided. However, the present exemplary embodiment is not limited thereto, and even when the texturing pattern 231 is not formed on the N-type semiconductor layer 230, the conductive anti-reflection film 400 is formed on the N-type semiconductor layer to extract light efficiency. (External quantum efficiency) can be improved.

The transparent cover layer 300 is provided on the total reflection prevention film 400. The transparent cover layer 300 includes a transparent electrode layer 310 coated on the total reflection prevention film 400 and a transparent substrate 320 provided on the transparent electrode layer 310.

As described above, the transparent electrode layer 310 preferably uses ITO. Although not shown, an external power pad is provided on one side of the transparent electrode layer 310 to receive power from the outside. It is preferable to use a polymer substrate as the transparent substrate 320. The transparent substrate 320 may be formed of a material having a refractive index similar to that of the transparent electrode layer 310. Similarity here means that the difference is less than about 20%. In this embodiment, polyethylene naphthalate (PEN) is used as the transparent substrate 320. Of course, the present invention is not limited thereto, and the transparent substrate 320 may be manufactured using various polymer materials.

In the above-described embodiment, a backlight light source in which a plurality of LED elements are mounted on a flexible substrate has been described. However, the present invention is not limited thereto, and the present invention can also be applied to a backlight light source in which a single LED element is mounted on a non-flexible insulating substrate or a conductive substrate.

Hereinafter, the liquid crystal display device having the above-described backlight light source will be described.

9 is an exploded perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment.

Referring to FIG. 9, the liquid crystal display according to the present exemplary embodiment includes a backlight 2000 including a backlight light source 600, a liquid crystal display panel 1200, a mold frame 1400, and an upper accommodating member 1100. do.

In the above, the liquid crystal display panel 1200 includes a common electrode substrate 1210 and a thin firm transistor (TFT) substrate 1220. The driving circuit unit 1300 is connected to one side of the liquid crystal display panel 1200. In this case, the driving circuit unit 1300 may include a printed circuit board 1310 that receives and provides an external data signal and a power signal, and a flexible printed circuit board that connects the printed circuit board 1310 and the liquid crystal display panel 1200. (1320). In the present exemplary embodiment, a control IC 1211 for applying a data signal to a data line is mounted on the thin film transistor substrate 1220 of the liquid crystal display panel 1200 as shown in FIG. 9. Of course, the present invention is not limited thereto, and the control IC 1211 may be mounted on the printed circuit board 1310 or the flexible printed circuit board 1320. Although not shown in the drawing, a gate stage unit is provided at one side of the thin film transistor substrate 1220 to receive a gate signal from the printed circuit board 1310 and supply the gate signal to the gate line.

The backlight 2000 of this embodiment includes a light source 600 for backlight and a plurality of optical sheets 700. In addition, the backlight light source 600 and the optical sheet 700 are accommodated in the lower accommodating member 800.

The backlight light source 600 includes a flexible substrate 100 on which an LED element having a texturing pattern is provided in a light emitting direction, a total reflection prevention film 400 provided on the flexible substrate 100, and a total reflection prevention film 400. It includes a cover layer 300 provided in. In order to protect the LED device on the flexible substrate 100, a buffer layer 500 is further provided on a portion of the region between the total reflection prevention film 400 and the flexible substrate 100. It is preferable that a reflective film is provided on an upper portion of the flexible substrate 100, and conductive wires are provided on a lower portion thereof to be electrically connected to the LED device. As a result, the backlight may not include a separate reflective film.

The optical sheet 700 includes a diffusion sheet and a brightness enhancement sheet. In this case, the diffusion sheet directs the light incident from the backlight light source 600 toward the front of the liquid crystal display panel 1200, diffuses the light to have a uniform distribution in a wide range, and irradiates the liquid crystal display panel 1200. . The brightness enhancing sheet transmits light parallel to its transmission axis and reflects light perpendicular to the transmission axis.

In the present embodiment, a mold frame 1400 is provided to fix and support the backlight light source and the optical sheet inside the lower housing member 800. The liquid crystal display panel 1200 is disposed on the mold frame 1400. An upper accommodating member 1100 is provided above the liquid crystal display panel 1200 such that the liquid crystal display panel 1200 is not separated.

As described above, the present invention can improve the external quantum efficiency of the LED device by applying a material film having a refractive index larger than the refractive index of the GaN film on the LED device including the GaN film.

In addition, the present invention is disposed between the LED element and the transparent electrode layer to reduce the total reflection of light generated in the boundary region of the LED element and the upper layer by placing a material having a refractive index smaller than the refractive index of the LED element and larger than the refractive index of the transparent electrode layer to reduce external quantum The efficiency can be improved.

Moreover, this invention can arrange | position a some LED element between flexible board | substrates, and can manufacture the light source for backlight which has flexibility.

Although the invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the invention is not limited thereto, but is defined by the claims that follow. Accordingly, one of ordinary skill in the art may variously modify and modify the present invention without departing from the spirit of the following claims.

Claims (18)

Board; A plurality of LED elements mounted on the substrate; A transparent electrode layer provided on the plurality of LED elements; A total reflection prevention film provided between at least the plurality of LED elements and the transparent electrode layer; And Light source for a backlight comprising a transparent substrate provided on the transparent electrode layer. The method according to claim 1, And a buffer layer provided on the substrate in a region between the plurality of LED elements. The method according to claim 1, The total reflection prevention film is a light source for a backlight using a material film having a refractive index larger than the refractive index of the semiconductor layer of the LED device. The method according to claim 1, The total reflection preventing film has a refractive index smaller than the refractive index of the semiconductor layer of the LED device, and uses a material film having a refractive index larger than the transparent electrode layer. The method according to claim 1, And a texturing pattern provided on the LED element surface in contact with the total reflection prevention film. The method according to claim 5, The texturing pattern includes a pyramid-shaped protrusion, and the total reflection prevention layer fills at least a portion of the area between the protrusions or is provided along the texturing pattern. The method according to claim 1, The LED device includes a P-type semiconductor layer connected to the substrate, an N-type semiconductor layer connected to the total reflection prevention film, and an active layer provided between the P-type semiconductor layer and the N-type semiconductor layer. The method according to claim 7, The N-type semiconductor layer is a GaN film, and the total reflection prevention film is TiO ₂ light source. The method according to claim 7, The N-type semiconductor layer is a GaN film, the transparent electrode layer is ITO, the total reflection prevention film is ZnO ₂ light source. The method according to claim 1, The substrate is a light source for a backlight is a flexible substrate. Mounting a plurality of LED elements on a substrate; Forming a buffer layer on a substrate in the region between the LED elements; Forming a total reflection prevention film on at least the LED element; Forming a transparent electrode layer on the total reflection prevention film; And Method of manufacturing a light source for a backlight comprising the step of attaching a transparent substrate on the transparent electrode layer. The method according to claim 11, For the backlight using a material film having a refractive index larger than the refractive index of the semiconductor layer of the LED device as the total reflection prevention film, or a material film having a refractive index smaller than the refractive index of the semiconductor layer of the LED device, and having a refractive index larger than the transparent electrode layer. Method of making the light source. Board; An LED device having an N-type semiconductor layer and a P-type semiconductor layer, and mounted such that the P-type semiconductor layer is in contact with the substrate; A total reflection prevention film including a material having a larger refractive index than the N-type semiconductor layer and provided on the N-type semiconductor layer of the LED device; A transparent electrode layer provided on the total reflection prevention film; And Light source for a backlight comprising a cover layer provided on the transparent electrode layer. Board; An LED device having an N-type semiconductor layer and a P-type semiconductor layer, and mounted such that the P-type semiconductor layer is in contact with the substrate; A transparent electrode layer provided on the LED element; A total reflection prevention film having a refractive index between the refractive index of the N-type semiconductor layer and the transparent electrode layer and provided between the N-type semiconductor layer and the transparent electrode layer; And Light source for a backlight comprising a cover layer provided on the transparent electrode layer. A light source for backlight to emit light; An optical sheet provided on the light source; A storage member for storing the backlight light source and the optical sheet; The backlight light source includes a substrate, a plurality of LED elements mounted on the substrate, a transparent electrode layer provided on the plurality of LED elements, a total reflection preventing film provided between at least the plurality of LED elements, and the transparent electrode layer, and the transparent layer. A backlight comprising a transparent substrate provided on the electrode layer. The method according to claim 15, The total reflection prevention film is a backlight using a material film having a refractive index larger than the refractive index of the semiconductor layer of the LED device, or a material film having a refractive index smaller than the refractive index of the semiconductor layer of the LED device, and having a refractive index larger than the transparent electrode layer. A liquid crystal display panel which displays an image; And A backlight for irradiating light to the liquid crystal display panel; The backlight includes a substrate, a plurality of LED elements mounted on the substrate, a transparent electrode layer provided on the plurality of LED elements, at least a total reflection preventing film provided between the plurality of LED elements and the transparent electrode layer, and the transparent electrode layer. A liquid crystal display device comprising the prepared transparent substrate. The method according to claim 17, The total reflection prevention film is a liquid crystal display using a material film having a refractive index larger than the refractive index of the semiconductor layer of the LED device or a material film having a refractive index smaller than the refractive index of the semiconductor layer of the LED device and having a refractive index larger than the transparent electrode layer. Device.

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