KR102632553B1 - Back light unit - Google Patents

Abstract

The present invention relates to backlight units. According to an embodiment of the present invention, a backlight unit includes a circuit board, at least one light emitting diode chip mounted on the circuit board, a plurality of reflective members disposed on the light emitting diode chip, and a light diffusion member. The light diffusion member has an incident surface through which light is incident and an exit surface through which light is emitted, and is disposed on an upper part of the circuit board. A plurality of reflective members are stacked on top of each other and reflect part of the light emitted from the top surface of the light emitting diode chip. Additionally, the incident surface of the light diffusion member covers the side surface of the light emitting diode chip, the side surface of the reflective member, and the top surface of the reflective member.

Description

Backlight unit{BACK LIGHT UNIT}

The present invention relates to backlight units.

A display device that is a light-receiving device without its own light source requires a separate light source device that can illuminate the entire screen from the back. A lighting device for such a display device is generally referred to as a backlight unit.

In general, backlight units are classified into edge-type and direct-type based on the way the light source that emits light, such as an LED chip, is arranged.

The edge-type backlight unit is a method in which a light source is placed on the side of a light diffusion member that guides light. However, the edge-type backlight unit has limitations in thinning the bezel of the display device because the light-emitting diode chip is arranged along the side of the light diffusion member. Additionally, the edge-type backlight unit generally has a problem in that it cannot be operated individually because a plurality of light emitting diode chips mounted on a circuit board are connected in series.

The direct backlight unit is a method of illuminating the front of the display panel by arranging a light source at the bottom of the light diffusion member. However, since the direct backlight unit has a light emitting diode chip disposed below the light diffusion member, there is a limit to reducing the thickness of the backlight unit and the display device.

The problem to be solved by the present invention is to provide a backlight unit that can reduce the thickness of a display device.

In addition, another problem to be solved by the present invention is to provide a backlight unit capable of local dimming and reduction of the thickness of the display device.

Another problem to be solved by the present invention is to provide a backlight unit with improved light efficiency by reducing the distance between the light diffusion member and the light emitting diode chip.

A backlight unit according to an embodiment of the present invention includes a circuit board, at least one light emitting diode chip mounted on the circuit board, a plurality of reflective members disposed on the light emitting diode chip, and a light diffusion member. The light diffusion member has an incident surface through which light is incident and an exit surface through which light is emitted, and is disposed on an upper part of the circuit board. A plurality of reflective members are stacked on top of each other and reflect part of the light emitted from the upper surface of the light emitting diode chip. Additionally, the incident surface of the light diffusion member covers the side surface of the light emitting diode chip, the side surface of the reflective member, and the top surface of the reflective member.

The backlight unit according to an embodiment of the present invention forms a cavity in the light diffusion member, and the thickness can be reduced by placing the light emitting diode chip in the cavity of the light diffusion member.

In the backlight unit according to an embodiment of the present invention, light emitting diode chips can be evenly disposed throughout the light diffusion member, enabling local dimming as well as thickness reduction.

1 to 3 are exemplary diagrams showing a backlight unit according to a first embodiment of the present invention.
Figure 4 is an exemplary diagram showing a light emitting diode chip and a reflective member according to the first embodiment.
Figure 5 is an exemplary diagram showing a light emitting diode chip and a reflective member according to a second embodiment.
Figure 6 is an exemplary diagram showing a backlight unit according to a second embodiment of the present invention.
Figure 7 is an exemplary diagram showing a backlight unit according to a third embodiment of the present invention.
Figure 8 is an exemplary diagram showing a backlight unit according to a fourth embodiment of the present invention.
Figure 9 is an exemplary diagram showing a backlight unit according to a fifth embodiment of the present invention.
10 to 13 are exemplary diagrams showing a backlight unit according to a sixth embodiment of the present invention.
Figure 14 is an exemplary diagram showing a backlight unit according to a seventh embodiment of the present invention.
Figure 15 is an exemplary diagram showing a backlight unit according to an eighth embodiment of the present invention.
Figure 16 is an exemplary diagram showing a backlight unit according to the ninth embodiment of the present invention.
Figure 17 is an exemplary diagram showing a backlight unit according to the tenth embodiment of the present invention.
Figure 18 is an exemplary diagram showing a backlight unit according to the 11th embodiment of the present invention.
Figure 19 is an exemplary diagram showing a backlight unit according to the twelfth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments introduced below are provided as examples to ensure that the idea of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And in the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Throughout the specification, like reference numbers indicate like elements and similar reference numbers indicate corresponding similar elements.

A backlight unit according to an embodiment of the present invention includes a circuit board, at least one light emitting diode chip mounted on the circuit board, a plurality of reflective members disposed on an upper portion of the light emitting diode chip, and a light diffusion member. The light diffusion member has an incident surface through which light is incident and an exit surface through which light is emitted, and is disposed on an upper part of the circuit board. The plurality of reflective members are stacked on each other and reflect a portion of light emitted from the upper surface of the light emitting diode chip. Additionally, the incident surface of the light diffusion member covers the side surface of the light emitting diode chip, the side surface of the reflective member, and the top surface of the reflective member.

The plurality of reflective members may have different areas. For example, the plurality of reflective members have a smaller area as the distance from the top surface of the light emitting diode chip increases.

The plurality of reflective members may be Distributed Bragg Reflectors (DBR). Alternatively, the plurality of reflective members may be made of metal.

At least one reflective member among the plurality of reflective members may be made of a different material from the other reflective members.

Additionally, at least one reflective member among the plurality of reflective members may have a different thickness from the other reflective members.

The plurality of reflective members may be a translucent resin containing a reflective material.

According to one embodiment, the incident surface of the light diffusion member may be in close contact with a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.

The backlight unit may further include a wavelength conversion member.

For example, the wavelength conversion member may cover the side and top surfaces of the light emitting diode chip. At this time, the incident surface of the light diffusion member may be in close contact with a side surface of the wavelength conversion member, a side surface of the reflective member, and a top surface of the reflective member.

Alternatively, the wavelength conversion member may cover a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member. At this time, the incident surface of the light diffusion member may be in close contact with the side and top surfaces of the wavelength conversion member.

The emission surface of the light diffusion member may be flat.

Alternatively, the emission surface of the light diffusion member may further include a convex portion that is convex in an upward direction. At this time, the convex portion is located on top of each light emitting diode chip.

The curvatures of the incident surface and the exit surface of the light diffusion member may be different from each other.

The light refractive index of the incident surface and the emission surface of the light diffusion member may be different from each other.

According to another embodiment, the incident surface of the light diffusion member may be spaced apart from a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.

The backlight unit may further include a sealing member disposed between the light emitting diode chip and an incident surface of the reflective member and the light diffusion member.

Additionally, the backlight unit may further include a reflective sheet disposed below the light diffusion member.

Additionally, the backlight unit may further include a light diffusion material dispersed within the light diffusion member.

Additionally, the backlight unit may further include a diffusion sheet disposed on an upper portion of the light diffusion member.

Additionally, the backlight unit may further include a wavelength conversion sheet disposed on top of the light diffusion member.

This will be described in detail below with reference to the drawings.

1 to 3 are exemplary diagrams showing a backlight unit according to a first embodiment of the present invention.

Figure 1 is a top plan view briefly showing the backlight unit 100 according to the first embodiment. Additionally, FIG. 2 shows the backlight unit 100 with the light diffusion member 110 and the light emitting diode chip 130 separated, and FIG. 3 is a cross-sectional view of FIG. 1 .

Referring to FIG. 1 , the backlight unit 100 according to the first embodiment includes a light diffusion member 110, a circuit board 120, a light emitting diode chip 130, and a reflective member 140.

The light diffusion member 110 is made of a transparent material. For example, the light diffusion member 110 may include one of an acrylic resin such as polymethyl methacrylate (PMMA), polyethylene terephthlate (PET), poly carbonate (PC), and polyethylene naphthalate (PEN) resin.

According to an embodiment of the present invention, at least one cavity 111 is formed on the lower surface of the light diffusion member 110. The cavity 111 is formed on the lower surface of the light diffusion member 110, but does not have a structure that penetrates to the upper surface. Additionally, the cavity 111 has a structure that corresponds to the outer shape of the light emitting diode chip 130 and the reflective member 140 disposed inside the light diffusion member 110.

The cavity 111 of the light diffusion member 110 accommodates the light emitting diode chip 130 and the reflective member 140 disposed on the upper surface of the light emitting diode chip 130.

Although not shown in the embodiment of the present invention, the backlight unit 100 includes optical sheets located on the light diffusion member 110 to diffuse and converge light.

A circuit board 120 on which a light emitting diode chip 130 is mounted is disposed below the light diffusion member 110. The circuit board 120 is electrically connected to the light emitting diode chip 130 and supplies power so that the light emitting diode chip 130 emits light.

Referring to this embodiment, the upper surface of the light diffusion member 110 includes a convex portion 113. The convex portion 113 is a portion of the upper surface of the light diffusion member 110 that is convex upward. For example, the convex portion 113 has a hemispherical structure. The convex portion 113 is located at the top of the light emitting diode chip 130. Referring to FIG. 3, the convex portion 113 surrounds the side and top surfaces of the light emitting diode chip 130. Additionally, the convex portion 113 is formed to surround each of the plurality of light emitting diode chips 130. The inner surface forming the cavity 111 of the light diffusion member 113 is an incident surface where the light of the light emitting diode chip 120 is incident. Additionally, the upper surface of the light diffusion member 113 is an exit surface through which light is emitted to the outside.

The emission surface of the light diffusion member 110 is composed of a flat surface and a curved surface forming the convex portion 113. As shown in FIG. 2, the light diffusion member 110 has different curvatures of the incident surface and the exit surface.

According to this embodiment, the light emitted from the light emitting diode chip 130 is refracted while passing through the entrance surface of the concave structure inside the light diffusion member 110, spreads widely, and is primarily scattered. Additionally, when the light incident on the light diffusion member 110 is emitted to the outside of the light diffusion member 110, it is refracted by the structure of the convex portion 113 and is secondaryly scattered. That is, light spreads evenly to the upper part of the light diffusion member 110 due to the structure of the incident surface that is concave inside the light diffusion member 110 and the convex portion 113 that is convex toward the top. Since the light is emitted while spreading evenly from the convex portions 113, the light emitted from each convex portion 113 may intersect in the space between adjacent convex portions 113. Therefore, the backlight unit 100 according to the present embodiment divides the space between each light emitting diode chip 130 by the light diffusion member 110 including an internally concave entrance surface and an exit surface having a convex portion 113. It can prevent dark spots from occurring in the upper part.

Additionally, since the light diffusion member 110 has an emission surface curvature due to the convex portion 113, the phenomenon of total reflection of light at the emission surface can be reduced. In the backlight unit 100 of this embodiment, the total reflection phenomenon of light is reduced, and thus light extraction efficiency is improved. The light emitting diode chip 130 is mounted on the circuit board 120 and positioned in the cavity 111 of the light diffusion member 110. If a plurality of cavities 111 are formed in the light diffusion member 110, a light emitting diode chip 130 may be disposed in each cavity 111.

According to an embodiment of the present invention, the light emitting diode chip 130 emits light through the top and side surfaces. The structure of the light emitting diode chip 130 will be described in detail later.

In this embodiment, the side surface of the light emitting diode chip 130 is in close contact with the entrance surface, which is the inner surface forming the cavity 111 of the light diffusion member 110. Light emitted from the side of the light emitting diode chip 130 is directly incident on the incident surface of the light diffusion member 110. Here, the light emitted from the side of the light emitting diode chip 130 is generated in the active layer (not shown) of the light emitting diode chip 130 and passes directly through the side of the light emitting diode chip 130 or is reflected by the reflective member 140. This is the light that passes through the side of the light emitting diode chip 130.

A reflective member 140 composed of a single layer or multiple layers is formed on the upper surface of the light emitting diode chip 130. For example, the first to third reflective members 141 to 143 are sequentially stacked on the upper surface of the light emitting diode chip 130.

According to this embodiment, a second reflective member 142 having an area smaller than the first reflective member 141 is disposed on the first reflective member 141. For example, the first reflective member 141 may be formed to cover the entire surface of the light emitting diode chip 130. At this time, the second reflective member 142 is located within the area of the first reflective member 141. Additionally, a third reflective member 143 having an area smaller than that of the second reflective member 142 is disposed on the second reflective member 142 . At this time, the third reflective member 143 is located within the area of the second reflective member 142.

The first to third reflective members 141 to 143 formed in this way reflect part of the light passing through the upper surface of the light emitting diode chip 130 and reflect the cavity 111, which is the incident surface of the light diffusion member 110. It can be made to be incident on the inner surface.

In this embodiment, the top and side surfaces of the reflective member 140 are in close contact with the inner surface forming the cavity 111 of the light diffusion member 110. Light passing through the reflective member 140 is incident on the inner surface of the light diffusion member 110 that is in close contact with the reflective member 140.

That is, among the inner surfaces of the light diffusion member 110, the inner side that is in close contact with the side surface of the light emitting diode chip 130 contains light emitted from the side surface of the light emitting diode chip 130 and the first to third reflection members 141. Light reflected by the member 143 is incident. In addition, among the inner surfaces of the light emitting diode chip 130, light passing through the reflective member 140 is incident on the upper surface that is in close contact with the reflective member 140, excluding the inner side.

The light reflectance of the first to third reflective members 141 to 143 may vary depending on material, thickness, area, etc. Accordingly, by adjusting the light reflectance of the first reflective member 141 and the third reflective member 143, the amount of light directed toward the inner side of the light diffusion member 110 can be adjusted. Here, the inner side of the light diffusion member 110 is a part of the light diffusion member 110 that is in close contact with the side of the light emitting diode chip 130, and is further in close contact with the side of the first reflection member 141. Therefore, by adjusting the light reflectance of the first reflection member 141 and the third reflection member 143, the light emitted from the upper surface of the light diffusion member 110 through the inner side of the light diffusion member 110 and the light diffusion member 110 are adjusted. The ratio of light emitted from the upper surface of the light diffusion member 110 can be adjusted through the inner upper surface of 110. Furthermore, by using the reflective member 140, the ratio of light emitted from the flat emission surface of the light diffusion member 110 and the emission surface corresponding to the convex portion 113 is adjusted, so that the emission of the light diffusion member 110 The light uniformity of the entire surface can be controlled.

The first to third reflective members 141 to 143 may be formed of any material capable of reflecting at least part of the light. The first to third reflective members 141 to 143 may be made of Distributed Bragg Reflectors (DBR). For example, DBR may be composed of one layer of one of SiO ₂ , TiO ₂ , SiN, and TiN. Alternatively, the DBR may have a structure in which at least two of each layer made of SiO ₂ , TiO ₂ , SiN, and TiN are stacked once or repeatedly. Alternatively, the first to third reflective members 141 to 143 may be made of metal such as Ag or Al. Alternatively, some of the first to third reflection members 141 to 143 may be made of metal, and other reflection members may be made of DBR. In an embodiment of the present invention, a structure in which the reflective member is composed of three layers is used as an example for explanation, but the number of layers of the reflective member may be changed depending on the thickness of the reflective member, material, and light quantity control.

In the light emitting device 100 according to this embodiment, the light diffusion member 110, the light emitting diode chip 130 through which light is emitted, and the reflection member 140 are in close contact with each other. Accordingly, the light emitted from the light emitting diode chip 130 and the reflection member 140 is directly irradiated to the light diffusion member 110 without passing through another medium.

The light diffusion member 110 may be formed by injection molding. The light diffusion member 110 is made by injecting the material of the light diffusion member into a mold designed to have a cavity 111 with an inner surface of a shape corresponding to the structure of the light emitting diode chip 130 and the reflection member 140 and then pressing it. can be formed. The light emitting diode chip 130 and the reflective member 140 may be inserted into the cavity 111 of the injection molded light diffusion member 110. At this time, since the cavity 111 is formed in a structure corresponding to the light emitting diode chip 130 and the reflective member 140, the light emitting diode chip 130 and the reflective member 140 are placed in the cavity 111 of the light diffusion member 110. ) can be fixed.

Conventional edge-type backlight units have limitations in thinning the bezel of the display device because the light-emitting diode chips are arranged along the side of the light diffusion member. Additionally, the edge-type backlight unit generally has a problem in that it cannot be operated individually because a plurality of light emitting diode chips mounted on a circuit board are connected in series.

Additionally, since the conventional direct-type backlight unit has a light emitting diode chip disposed below the light diffusion member, there is a limit to reducing the thickness of the backlight unit and the display device.

However, in the backlight unit 100 according to an embodiment of the present invention, the light emitting diode chip 130 is not located below the light diffusion member 110, but is located inside the light diffusion member 110 through the cavity 111. Therefore, the thickness of the backlight unit 100 and the display device can be reduced. Additionally, the backlight unit 100 according to an embodiment of the present invention can implement local dimming that individually controls the light emitting diode chip 130 through the circuit board 120. Additionally, according to an embodiment of the present invention, the backlight unit 100 can easily control the light reflectance of the reflective member 140 using the size, number of layers, material, etc. of the reflective member 140. Accordingly, the backlight unit 100 of this embodiment is easy to control the light necessary to ensure that the uniformity of the light emitted through the upper surface of the light diffusion member 110 and the light emitted into the upper part of the cavity 1110 is 90% or more. Furthermore, since the backlight unit 100 can emit light uniformly, spotting of a display device (not shown) to which the backlight unit 100 is applied can be minimized.

In addition, in the backlight unit 100 of this embodiment, the surface of the light emitting diode chip 130 from which light is emitted, the surface of the reflection member 140, and the light diffusion member 110 are in close contact with each other. Such a backlight unit 100 improves light extraction efficiency and light diffusion member ( 110), light uniformity on the upper surface can be improved.

Figure 4 is an exemplary diagram showing a light emitting diode chip and a reflective member according to the first embodiment.

The light emitting diode chip 10 of this embodiment is an example of a light emitting diode chip of a backlight unit (100 in FIGS. 1 to 3). The light emitting diode chip 10 of this embodiment has a horizontal structure in which electrodes of both polarities are formed at the bottom.

Referring to FIG. 4, the light emitting diode chip 10 includes a substrate 11, a light emitting structure 12, a transparent electrode layer 16, a first electrode pad 17, a second electrode pad 18, and a reflective layer 19. may include.

The substrate 11 is not particularly limited as long as it is a transparent substrate. For example, the substrate 11 may be a sapphire or SiC substrate. Additionally, the substrate 11 may be a growth substrate suitable for growing gallium nitride-based compound semiconductor layers, such as a patterned sapphire substrate (PSS).

The light emitting structure 12 is disposed below the substrate 11. The light emitting structure 12 includes a first conductive semiconductor layer 13, a second conductive semiconductor layer 15, and an active layer interposed between the first conductive semiconductor layer 13 and the second conductive semiconductor layer 15. Includes (14). Here, the first conductivity type and the second conductivity type are opposite conductivity types, and the first conductivity type may be n-type and the second conductivity type may be p-type, or vice versa.

The first conductive semiconductor layer 13, the active layer 14, and the second conductive semiconductor layer 15 may be formed of a gallium nitride-based compound semiconductor material. The first conductive semiconductor layer 13 and the second conductive semiconductor layer 15 may be formed as a single layer as shown in FIG. 4. Alternatively, at least one of the first conductivity type semiconductor layer 13 and the second conductivity type semiconductor layer 15 may be formed in a multilayer structure. The active layer 14 may be formed in a single quantum well or multiple quantum well structure. Although not shown in FIG. 4, a buffer layer may be formed between the substrate 11 and the first conductive semiconductor layer 13.

The first conductivity type semiconductor layer 13, the second conductivity type semiconductor layer 15, and the active layer 14 may be formed using silver MOCVD or MBE technology. Additionally, the second conductive semiconductor layer 15 and the active layer 14 may be patterned to expose a partial area of the first conductive semiconductor layer 13 through a photo and etching process. At this time, a portion of the first conductive semiconductor layer 13 may also be patterned.

The transparent electrode layer 16 is disposed on the lower surface of the second conductive semiconductor layer 15. For example, the transparent electrode layer 16 may be formed of ITO, ZnO, or Ni/Au. The transparent electrode layer 16 has lower specific resistance than the second conductive semiconductor layer 15 and can disperse current.

The first electrode pad 17 is disposed under the first conductive semiconductor layer 13, and the second electrode pad 18 is disposed under the transparent electrode layer 16. The second electrode pad 18 is electrically connected to the second conductive semiconductor layer 15 through the transparent electrode layer 16.

The reflective layer 19 is formed to cover the lower portion of the light emitting structure 12 excluding the first electrode pad 17 and the second electrode pad 18. Additionally, the reflective layer 19 is formed to cover the side surfaces of the active layer 14 and the second conductive semiconductor layer 15 exposed by patterning to expose the first conductive semiconductor layer 13.

The reflective layer 19 formed in this way reflects light generated in the active layer 14 and traveling toward the second electrode pad 18, and directs it toward the top or side of the light emitting diode chip 10. Accordingly, all light generated from the light emitting structure 12 can be emitted only from the light emitting surface.

The reflective layer 19 may be an insulating layer made of a single or multi-layer DBR or a metal layer surrounded by an insulating layer. The position and structure where the reflective layer 19 is formed is not limited to the structure shown in FIG. 4. The position and structure of the reflective layer 19 can be changed in various ways as long as it can reflect light directed to the second electrode pad 18.

First to third reflective members 141 to 143 are disposed on the upper surface of the light emitting diode chip 10.

The first reflective member 141 is disposed on the upper surface of the substrate 11 of the light emitting diode chip 10. At this time, the first reflective member 141 may be formed to cover the entire upper surface of the substrate 11. If the first reflective member 141 is formed to have a smaller area than the substrate 11, light is directly emitted only from the portion of the substrate 11 exposed to the outside, which is significantly different from the amount of light emitted through other portions or the light diffusion member. There may be a difference.

The second reflective member 142 is disposed on the upper surface of the first reflective member 141. The second reflective member 142 has a smaller area than the first reflective member 141.

Additionally, the third reflective member 143 is disposed on the upper surface of the second reflective member 142. The third reflective member 143 has a smaller area than the second reflective member 142.

Part of the light heading toward the top of the light emitting diode chip 10 is reflected by the first reflective member 141, and the other part passes through the first reflective member 141. At this time, part of the light passing through the first reflective member 141 is emitted to the outside, and the other part is directed to the second reflective member 142. Part of the light heading from the first reflective member 141 to the second reflective member 142 is reflected by the second reflective member 142, and the other part passes through the second reflective member 142. At this time, part of the light passing through the second reflection member 142 is emitted to the outside, and the other part is directed to the third reflection member 143. Part of the light heading from the second reflection member 142 to the third reflection member 143 is reflected by the third reflection member 143, and the other part passes through the third reflection member 143. In this way, light emitted from the top of the light emitting diode chip 10 through the first to third reflective members 141 to 143 having different areas and light emitted through the side of the light emitting diode chip 10 The amount of light can be adjusted.

In addition, when the reflective member disposed on the upper surface of the light emitting diode chip 10 is not a single layer but is formed as a multi-layer structure with a gradually decreasing area, the reflectance can be adjusted using the material and thickness of each layer, thereby enabling more detailed light quantity control. This is possible.

Although omitted in the embodiment of the present invention, an ohmic contact ( An ohmic contact layer for (Ohmic contact) may be located.

Figure 5 is an exemplary diagram showing a light emitting diode chip and a reflective member according to a second embodiment.

The light emitting diode chip 20 of this embodiment is another embodiment of the light emitting diode chip of the backlight unit (100 in FIGS. 1 to 3). The light emitting diode chip 20 of this embodiment has a vertical structure with one electrode formed at the top and bottom.

When describing the light emitting diode chip 20 according to the second embodiment, description of the same components as the light emitting diode chip (10 in FIG. 4) according to the first embodiment will be omitted. For omitted descriptions, refer to the description of FIG. 4.

Referring to FIG. 5 , the light emitting diode chip 20 may include a conductive substrate 21, a light emitting structure 12, a first electrode pad 17, and a reflective layer 22.

The conductive substrate 21 not only supports the light emitting structure 12, but is also electrically connected to the second conductive semiconductor layer 15 and may also serve as a second electrode pad.

The light emitting structure 12 is located on top of the conductive substrate 21. The light emitting structure 12 has a structure in which a second conductive semiconductor layer 15, an active layer 14, and a first conductive semiconductor layer 13 are sequentially stacked on the conductive substrate 21.

A reflective layer 22 may be formed between the conductive substrate 21 and the second conductive semiconductor layer 15 to reflect light generated in the active layer 14 and emitted in the direction of the conductive substrate 21. The reflective layer 22 may be formed of a conductive material to electrically connect the conductive substrate 21 and the second conductive semiconductor layer 15. This reflective layer 22 can also serve as an ohmic contact layer between the conductive substrate 21 and the second conductive semiconductor layer 15.

A first electrode pad 17 is formed on a portion of the upper part of the first conductive semiconductor layer 13. An ohmic contact layer may also be formed between the first conductive semiconductor layer 13 and the first electrode pad 17.

The first to third reflective members 141 to 143 may be formed on the first conductive semiconductor layer 13 excluding the portion where the first electrode pad 17 is formed.

The first to third reflective members 141 to 143 may be made of DBR. If the first reflective member 141 and the third reflective member 143 are made of metal, an insulating layer is further formed to insulate the first electrode pad 17 and the first conductive semiconductor layer 13. It should be. Alternatively, the first electrode pad 17 may be omitted, and the first to third reflective members 141 to 143 may also serve as the first electrode pad 17.

In this way, it is easy to control the amount of light emitted from the top and sides of the light emitting diode chip 20 by the first to third reflection members 141 to 143. Additionally, if the first reflective member 141 and the third reflective member 143 serve as the first electrode pad 17, the first electrode pad 17 may be omitted. Accordingly, it is possible to control the location and amount of light from the light emitting diode chip 20 while simplifying the structure.

4 and 5, an example in which the reflective member 140 is formed on a light emitting diode chip having a horizontal structure and a vertical structure has been described. However, the structure of the light emitting diode chip applied to the embodiment of the present invention is not limited to FIGS. 4 and 5. The light emitting diode chip can have any structure capable of wire bonding and flip chip bonding. Additionally, the reflective member 140 may be formed on any part of the light emitting diode chip 130 that requires light quantity control.

In addition, light emitting diode chips of various structures to which the reflective member 140 is applied may be applied to other embodiments of the backlight unit in the future.

Hereafter, when various embodiments are described, parts already described in previous embodiments will be omitted or simply described. Therefore, for detailed descriptions of briefly described configurations and configurations whose descriptions are omitted, refer to previous embodiments.

Figure 6 is an exemplary diagram showing a backlight unit according to a second embodiment of the present invention.

Referring to FIG. 6, the backlight unit 200 according to the second embodiment includes a light diffusion member 110, a circuit board 120, a light emitting diode chip 130, a reflection member 140, and a wavelength conversion member 210. Includes.

The backlight unit 200 of this embodiment includes a light emitting diode chip 130 and a wavelength conversion member 210 surrounding the reflective member 140. At this time, the inner surface of the light diffusion member 110 forming the cavity 111 is formed in a structure corresponding to the wavelength conversion member 210 and is in close contact with the wavelength conversion member 210. Accordingly, the wavelength-converted light emitted through the wavelength conversion member 210 is directly incident on the light diffusion member 110.

The wavelength conversion member 210 converts the wavelength of light emitted from the light emitting diode chip 130 to emit white light or light of a specific color.

The wavelength conversion member 210 may be a transparent resin mixed with a phosphor that converts the wavelength of light. For example, the transparent resin may be transparent silicone. As the phosphor, yellow phosphor, red phosphor, green phosphor, etc. may be used.

Examples of yellow phosphors include YAG:Ce (T ₃ Al ₅ O ₁₂ :Ce) series phosphors, which are cerium (Ce)-doped yttrium (Y) aluminum (Al) garnets with a main wavelength of 530 to 570 nm, or silicates. ) series of phosphors.

Examples of red (R) phosphors include the YOX (Y ₂ O ₃ :EU) series phosphor or nitride phosphor, which is composed of a compound of yttrium oxide (Y ₂ O ₃ ) and europium (EU) with a main wavelength of 611 nm. I can hear it.

An example of a green (G) phosphor is the LAP (LaPO ₄ :Ce, Tb) series phosphor, which is a compound of phosphoric acid (PO ₄ ), lanthanum (La), and terbium (Tb) with a main wavelength of 544 nm.

Examples of blue (B) phosphors include the BAM (BaMgAl ₁₀ O ₁₇ :Eu) series, a compound of barium (Ba), magnesium (Mg), and aluminum oxide series with a main wavelength of 450 nm, and europium (EU). A phosphor may be mentioned.

Additionally, the phosphor may include the fluoride compound KSF phosphor (K ₂ SiF ₆ ), which is a Mn4+ activator phosphor that is advantageous for high color reproduction.

In this way, the wavelength of light emitted from the side of the light emitting diode chip 130 and the wavelength of light passing through the reflective member 140 are converted by the wavelength conversion member 210 surrounding the light emitting diode chip 130 and the reflective member 140. Everything can be converted.

Figure 7 is an exemplary diagram showing a backlight unit according to a third embodiment of the present invention.

Referring to FIG. 7, the backlight unit 300 according to the third embodiment includes a light diffusion member 110, a circuit board 120, a light emitting diode chip 130, a reflection member 140, and a wavelength conversion member 210. Includes.

The backlight unit 300 of this embodiment includes a wavelength conversion member 210 surrounding the light emitting diode chip 130.

In this embodiment, the wavelength conversion member 210 is formed to surround the side and top surfaces of the light emitting diode chip 130. At this time, the bottom layer of the reflective member 140 may be formed to cover the entire upper surface of the wavelength conversion member 210. Accordingly, the inner side of the light diffusion member 110 is in close contact with the side of the wavelength conversion member 210, and the inner upper surface of the light diffusion member 110 is in close contact with the reflection member 140.

Light emitted from the side of the light emitting diode chip 130 is converted to wavelength and is directed to the light diffusion member 110. Additionally, the light emitted from the top surface of the light emitting diode chip 130 is converted to wavelength and is directed to the reflective member 140. That is, since the light reflected by the reflective member 140 has already undergone wavelength conversion on the top surface of the light emitting diode chip 130, there is no need for wavelength conversion on the side of the light emitting diode chip 130. Accordingly, since the wavelength conversion member 210 located on the side portion of the light emitting diode chip 130 does not need to consider the light reflected by the reflective member 140, there is no need to increase the phosphor content or make it thicker. In other words, the wavelength conversion member 210 can achieve uniform light wavelength conversion as a whole even if its top thickness and side thickness are adjusted considering only the light emitted from the top and sides of the light emitting diode chip 130.

Figure 8 is an exemplary diagram showing a backlight unit according to a fourth embodiment of the present invention.

Referring to FIG. 8 , the backlight unit 400 according to the fourth embodiment includes a light diffusion member 110, a circuit board 120, a light emitting diode chip 130, and a reflective member 410.

According to this embodiment, the reflective member 410 may contain a reflective material 411 in a translucent resin. The light-transmitting resin forming the reflective member 410 may be a known material such as silicone resin, epoxy resin, etc. For example, the light-transmissive resin of the reflective member 410 may be a silicone resin whose refractive index difference with the light diffusion member 110 is 10% or less.

The reflective member 410 is located on the upper surface of the light emitting diode chip 130. Accordingly, the inner surface of the light diffusion member 110 is in close contact with the side surface of the light emitting diode chip 130, the side surface of the reflective member 410, and the upper surface of the reflective member 410. According to this embodiment, light emitted from the upper surface of the light emitting diode chip 130 may pass through the light-transmitting resin, be reflected by the reflective material 411, and be incident on the inner surface of the light diffusion member 110.

The reflective member 410 of this embodiment can control the amount of light reflected to be emitted from the top surface of the reflective member 410 or from the side of the light emitting diode chip 130 by adjusting the content of the reflective material 411.

Figure 9 is an exemplary diagram showing a backlight unit according to a fifth embodiment of the present invention.

Referring to FIG. 9 , the backlight unit 500 according to the fifth embodiment includes a light diffusion member 510, a circuit board 120, a light emitting diode chip 130, and a reflective member 140.

According to this embodiment, the light diffusion member 510 includes a convex portion 513 having a curved surface that is not spherical. For example, the convex portion 513 has a parabolic cross-sectional structure in which the height (h) is greater than the width (w) at both ends.

The convex portion 513 of this parabolic structure has a different curvature at each position from which light is emitted.

Additionally, the convex portion 513 has a larger area than when it has a hemispherical structure. That is, the light diffusion member 510 has a larger emission surface area due to the parabolic convex portion 513.

For example, as the height of the cross-section increases based on the width of the convex portion 513, light is refracted at different angles through a larger area of the convex portion 513, so the light may be scattered more widely.

Accordingly, the light scattered from the incident surface of the light diffusion member 510 and spread out is emitted at different angles over a larger area by the convex portion 513 of the parabolic structure, so that it can be scattered more widely.

In the backlight unit 500 according to this embodiment, light is scattered more widely in the convex portions 513 of the parabolic structure, and thus is emitted from adjacent convex portions 513 and the exit surface between the convex portions 513. The light can be better mixed.

Additionally, the backlight unit 500 according to this embodiment can control the amount of light emitted toward the top and the side of the light emitting diode chip 130 by the reflection member 140.

In this way, the backlight unit 500 can improve the uniformity of light emitted through the exit surface of the light diffusion member 510 by using the parabolic convex portion 513 and the reflective member 140.

10 to 13 are exemplary views showing a backlight unit according to a sixth embodiment of the present invention.

Referring to FIG. 10 , the backlight unit 600 according to the sixth embodiment includes a light diffusion member 610, a circuit board 120, a light emitting diode chip 130, and a reflective member 140.

According to this embodiment, the light diffusion member 610 has a structure in which the emission surface is flat. Therefore, the light diffusion member 610 according to this embodiment can be manufactured with only a simple process of flattening the upper surface without the step of molding to have a separate structure and the corresponding process. Alternatively, a light diffusion member with a separate structure needs to manufacture a mold into which the material of the light diffusion member is injected to correspond to the structure of the light diffusion member, but the light diffusion member 610 according to an embodiment of the present invention requires a separate mold. No production required. In addition, since the light diffusion member 610 according to an embodiment of the present invention only needs to have a flat upper surface, it can be formed with a simple process of flattening the upper surface no matter what structure the mold is used for.

Additionally, the light diffusion member 610 may be formed using a method other than injection molding using a mold.

For example, the light diffusion member 610 may be formed in the manner shown in FIGS. 11 to 13.

As shown in FIG. 11, first, a circuit board 120 and a light emitting diode chip 130 mounted on the circuit board 120 and having a reflective member 140 formed thereon are prepared.

Thereafter, as shown in FIG. 12, light diffusion resin 611 is applied on the circuit board 120. Light diffusion resin 611 is applied to cover the light emitting diode chip 130 and the reflective member 140. For example, the light diffusion resin 611 may be silicon resin. The light diffusion resin 611 is applied on the circuit board 120 and then cured.

Thereafter, the cured light diffusion resin 611 goes through a planarization process to become the light diffusion member 610 with a flat upper surface shown in FIG. 13.

The backlight unit 600 having this structure has a simpler manufacturing process and reduced costs compared to other light diffusion members having a separate structure for the light diffusion member 610 having a flat top structure.

In addition, the backlight unit 600 of this embodiment has a flat exit surface, which is the upper surface of the light diffusion member 610, but has an inwardly concave entrance surface, so light may be scattered on the entrance surface. Accordingly, the backlight unit 600 may emit light uniformly over the entire area of the emission surface of the light diffusion member 610.

Figure 14 is an exemplary diagram showing a backlight unit according to a seventh embodiment of the present invention.

Referring to FIG. 14, the backlight unit 700 according to the seventh embodiment of the present invention includes a housing 720, a light diffusion member 710, a circuit board 120, a light emitting diode chip 130, and a reflective member 140. ) includes.

The housing 720 has an open top structure, and a light emitting diode chip 130, a reflection member 140, and a light diffusion member 710 are disposed therein. The housing 720 may be made of a reflective material or may have a reflective material coated on its inner wall. In this case, the light emitted from the bottom and side of the light diffusion member 710 may be reflected from the inner wall of the housing 720 and re-incident into the light diffusion member 710, thereby improving the light efficiency of the backlight unit 700. You can do it. The backlight unit of another previously described embodiment also includes a housing 720.

According to this embodiment, the cavity 711 of the light diffusion member 710 has a square cross-section. Additionally, the light diffusion member 710 is formed so that the cavity 711 has a larger size than the light emitting diode chip 130 and the reflective member 140. That is, the cavity 711 of the light diffusion member 710 has a width greater than the width of the light emitting diode chip 130 and a height greater than the length from the bottom surface of the light emitting diode chip 130 to the top surface of the reflection member 140. has

Accordingly, in the backlight unit 700 of this embodiment, the light diffusion member 710 covers the light emitting diode chip 130 and the reflective member 140, but the incident surface of the light diffusion member 710 and the light emitting diode chip 130 and an empty space is formed between the reflective members 140.

In this embodiment, the cavity 711 of the light diffusion member 710 has a simple structure with a square cross-section. Therefore, manufacturing of the light diffusion member 710 is easy.

In addition, since the cavity 711 of the light diffusion member 710 is larger than the light emitting diode chip 130 and the reflective member 140, the light emitting diode chip 130 and the reflective member 140 are separated by the light diffusion member 710. can prevent damage. Or vice versa, the light diffusion member 710 can be prevented from being damaged by the light emitting diode chip 130 and the reflective member 140. That is, when the light diffusion member 710 covers the light emitting diode chip 130 and the reflective member 140, the inner wall (incident surface) of the cavity 711 of the light diffusion member 710 and the light emitting diode chip 130 or It is possible to prevent the reflective member 140 from colliding.

Figure 15 is an exemplary diagram showing a backlight unit according to an eighth embodiment of the present invention.

Referring to FIG. 15, the backlight unit 800 according to the eighth embodiment of the present invention includes a housing 720, a light diffusion member 710, a circuit board 120, a light emitting diode chip 130, and a reflective member 140. ) and a sealing member 810.

According to this embodiment, the sealing member 810 is formed between the light emitting diode chip 130, the reflective member 140, and the light diffusion member 710. That is, the sealing member 810 is formed on the circuit board 120 to cover the light emitting diode chip 130 and the reflective member 140. Such a sealing member 810 can improve the adhesion between the circuit board 120 and the light diffusion member 710.

For example, the sealing member 810 may be formed of a known light-transmissive material such as epoxy resin, silicone resin, etc. Additionally, the sealing member 810 may be formed of a material with a similar refractive index to that of the light diffusion member 710. If the sealing member 810 is made of a material that has a similar refractive index to the light diffusion member 710, the light from the light emitting diode chip 130 toward the light diffusion member 710 is transmitted at the interface between the light diffusion member 710 and the sealing member 810. Reflections can be minimized.

Figure 16 is an exemplary diagram showing a backlight unit according to the ninth embodiment of the present invention.

Referring to FIG. 16, the backlight unit 900 according to the ninth embodiment of the present invention includes a housing 720, a light diffusion member 610, a circuit board 120, a light emitting diode chip 130, and a reflective member 140. ) and a reflective sheet 910.

The reflective sheet 910 is disposed between the plurality of light emitting diode chips 130 on the upper surface of the circuit board 120. The reflective sheet 910 may reflect light emitted from the light emitting diode chip 130 toward the housing 720 so that it is incident on the light diffusion member 610 . Additionally, the reflective sheet 910 may reflect light emitted from the lower surface of the light diffusion member 610 so that it re-enters the light diffusion member 610. Accordingly, the light efficiency of the backlight unit 900 of this embodiment is improved by the reflective sheet 910.

In this embodiment, it has been described that the reflective sheet 910 is disposed on the upper surface of the circuit board 120, but the position where the reflective sheet 910 is disposed is not limited to this. When the circuit board 120 is a glass substrate that transmits light, the reflective sheet 910 may be disposed below the circuit board 120. Additionally, when the reflective sheet 910 is disposed inside the housing 720, the housing 720 may not be made of a reflective material or the reflective material coated on the inner wall of the housing may be omitted.

Figure 17 is an exemplary diagram showing a backlight unit according to the tenth embodiment of the present invention.

Referring to FIG. 17, the backlight unit 1000 according to the tenth embodiment of the present invention includes a housing 720, a light diffusion member 1010, a circuit board 120, a light emitting diode chip 130, and a reflective member 140. ) includes.

In this embodiment, the light diffusion material 1020 is dispersed inside the light diffusion member 1010. For example, the light diffusion material 1020 may be made of at least one of glass, an acrylic compound, a nylon-based compound, and a silicon-based compound.

In the backlight unit 1000 according to this embodiment, the light diffusion material 1020 is dispersed inside the light diffusion member 1010, thereby improving the uniformity of light emitted from the light diffusion member 1010.

Figure 18 is an exemplary diagram showing a backlight unit according to the 11th embodiment of the present invention.

Referring to Figure 18, the backlight unit 1100 according to the 11th embodiment of the present invention includes a light diffusion member 610, a circuit board 120, a light emitting diode chip 130, a reflection member 140, and a diffusion sheet ( 1110).

The backlight unit 1100 according to the 11th embodiment is different from the 10th embodiment in that a structure for light diffusion is disposed on the top of the light diffusion member 610 rather than inside the light diffusion member 610.

The diffusion sheet 1110 is disposed on top of the light diffusion member 610. The diffusion sheet 1110 diffuses the light incident through the light diffusion member 610 so that it is emitted in a uniform distribution over a wide range.

Therefore, the backlight unit 1100 according to this embodiment can improve light uniformity by using the diffusion sheet 1110.

The backlight units of the tenth and eleventh embodiments improve uniformity of light by using a light diffusion material dispersed inside a diffusion sheet or a light diffusion member. However, the configuration for diffusing light is not limited to this. Instead of the light diffusion material and the diffusion sheet, the backlight unit may be provided with a light diffusion member having a pattern for light diffusion formed on at least one of the upper and lower surfaces. Additionally, the backlight unit may include a configuration for diffusing light from at least two of a light diffusion material dispersed inside the light diffusion member, a light diffusion pattern formed on the surface of the light diffusion member, and a diffusion sheet.

Figure 19 is an exemplary diagram showing a backlight unit according to the twelfth embodiment of the present invention.

Referring to FIG. 19, the backlight unit 1200 according to the twelfth embodiment of the present invention includes a housing 720, a light diffusion member 610, a circuit board 120, a light emitting diode chip 130, and a reflective member 140. ) and a wavelength conversion sheet 1210.

In the backlight unit 1200 according to the twelfth embodiment, a wavelength conversion sheet 1210 is disposed on the light diffusion member 610. The wavelength conversion sheet 1210 converts the wavelength of light emitted from the light diffusion member 610 to emit white light or light of a specific color.

By using the wavelength conversion sheet 1210 disposed on the light diffusion member 610, the wavelength conversion members formed on each of the plurality of light emitting diode chips 130 can be omitted.

In the backlight units of the ninth to twelfth embodiments, one of a diffusion sheet, a reflection sheet, and a wavelength conversion sheet is disposed in a housing. However, the backlight unit of the present invention is not limited to this. The backlight unit may include at least two optical sheets among a diffusion sheet, a reflection sheet, and a wavelength conversion sheet. Additionally, the backlight unit according to an embodiment of the present invention may further include various optical sheets such as a prism sheet, a polarizing sheet, etc., as well as a diffusion sheet, a reflection sheet, and a wavelength conversion sheet.

Additionally, the light diffusion material, light diffusion pattern, and optical sheet of the backlight units of the seventh to twelfth embodiments of the present invention may be equally applied to the backlight units of the first to sixth embodiments of the present invention.

The backlight unit according to this embodiment can efficiently improve light uniformity by using a light diffusion material, a light diffusion pattern, and an optical sheet.

As described above, the specific description of the present invention has been made based on examples with reference to the accompanying drawings, but since the above-described embodiments are only explained by referring to preferred examples of the present invention, the present invention is limited to the examples only. It should not be understood, and the scope of rights of the present invention should be understood in terms of the claims and equivalent concepts described later.

11: substrate
12: Light-emitting structure
13: First conductive semiconductor layer
14: active layer
15: Second conductive semiconductor layer
16: Transparent electrode layer
17: first electrode pad
18: second electrode pad
19, 22: Reflective layer
21: conductive substrate
100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200: Backlight unit
110, 510, 610, 710, 1010: Light diffusion member
111, 711: cavity
113, 513: Convex portion
120: circuit board
10, 20, 130: light emitting diode chip
140, 410: Reflective member
141: first reflection member
142: second reflective member
143: Third reflective member
150: sealing member
210: Wavelength conversion member
411: reflective material
611: Light diffusion resin
720: housing
810: sealing member
910: reflective sheet
1020: Light diffusing material
1110: Diffusion sheet
1210: Wavelength conversion sheet

Claims (23)

circuit board;
At least one light emitting diode chip mounted on the circuit board;
a reflective member disposed on top of the light emitting diode chip; and
A light diffusion member has an incident surface through which light is incident and an exit surface through which light is emitted, and is disposed on an upper portion of the circuit board.
The reflective member has a plurality of layers repeatedly stacked, is located between the light emitting diode chip and the light diffusion member, and reflects a portion of the light emitted from the upper surface of the light emitting diode chip,
The incident surface of the light diffusion member covers a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.
In claim 1,
The reflective member includes layers with different areas,
A backlight unit in which a layer with a smaller area is located farther away from the top surface of the light emitting diode chip.
In claim 1,
A backlight unit in which the reflective member is a Distributed Bragg Reflector (DBR).
In claim 1,
A backlight unit wherein the reflective member includes a metal layer.
In claim 1,
A backlight unit wherein at least one layer of the reflective members has a different material from the other layers.
In claim 1,
A backlight unit wherein at least one layer of the reflective members has a different thickness from the other layers.
In claim 1,
A backlight unit wherein the reflective member includes a translucent resin containing a reflective material.
In claim 1,
The backlight unit wherein the incident surface of the light diffusion member is in close contact with a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.
In claim 1,
A backlight unit further comprising a wavelength conversion member covering side and top surfaces of the light emitting diode chip.
In claim 9,
The backlight unit wherein the incident surface of the light diffusion member is in close contact with a side surface of the wavelength conversion member, a side surface of the reflective member, and a top surface of the reflective member.
In claim 1,
The backlight unit further includes a wavelength conversion member covering a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.
In claim 11,
The backlight unit wherein the incident surface of the light diffusion member is in close contact with the side and top surfaces of the wavelength conversion member.
In claim 1,
A backlight unit wherein the emission surface of the light diffusion member is flat.
In claim 13,
The backlight unit wherein the emission surface of the light diffusion member further includes a convex portion that is convex in an upward direction.
In claim 14,
The convex portion is a backlight unit located on top of each light emitting diode chip.
In claim 1,
A backlight unit in which the curvatures of the incident surface and the emission surface of the light diffusion member are different from each other.
In claim 1,
A backlight unit wherein the light refractive index of the incident surface and the emission surface of the light diffusion member are different from each other.
In claim 1,
The backlight unit wherein the incident surface of the light diffusion member is spaced apart from a side surface of the light emitting diode chip, a side surface of the reflective member, and a top surface of the reflective member.
In claim 1,
The backlight unit further includes a sealing member disposed between the light emitting diode chip and the incident surface of the reflective member and the light diffusion member.
In claim 1,
A backlight unit further comprising a reflective sheet disposed below the light diffusion member.
In claim 1,
A backlight unit further comprising a light diffusion material dispersed inside the light diffusion member.
In claim 1,
A backlight unit further comprising a diffusion sheet disposed on an upper portion of the light diffusion member.
In claim 1,
A backlight unit further comprising a wavelength conversion sheet disposed on an upper portion of the light diffusion member.