KR20190090332A - Back light unit - Google Patents

Abstract

The present invention relates to a backlight unit. According to an embodiment of the present disclosure, the 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 diffusing member. The light diffusing member has an incident surface on which light is incident and an exit surface on which the light is emitted, and is disposed in the upper part of the circuit board. The plurality of reflective members is stacked on each other and reflects a part of the light emitted from the upper surface of the light emitting diode chip. Further, the incident surface of the light diffusing member covers the side surface of the light emitting diode chip, the side surface of the reflective member, and the upper surface of the reflective member. It is possible to reduce the thickness of a display device.

Description

Backlight unit {BACK LIGHT UNIT}

The present invention relates to a backlight unit.

A display device that is a light-receiving device without a self-emitting source requires a separate light source device capable of illuminating the entire screen from the back. A lighting device for such a display device is generally referred to as a backlight unit.

Generally, the backlight unit is divided into an edge type and a direct type according to the manner in which a light source emitting light is arranged, such as an LED chip.

In the edge type backlight unit, a light source is disposed on a side surface of a light diffusion member for guiding light. However, the edge type backlight unit has a limitation in thinning the bezel of the display device because the light emitting diode chip is disposed along the side surface of the light diffusing member. Further, the edge type backlight unit generally has a problem that a plurality of light emitting diode chips mounted on a circuit board are connected in series and can not be individually operated.

The direct-type backlight unit is a method of illuminating the front surface of the display panel by arranging a light source at a lower portion of the light diffusion member. However, the direct-type backlight unit has a limitation in reducing the thickness of the backlight unit and the display device because the light-emitting diode chip is disposed under the light diffusion member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backlight unit capable of reducing the thickness of a display device.

Another object of the present invention is to provide a backlight unit capable of local dimming and capable of reducing the thickness of a display device.

Another object of the present invention is to provide a backlight unit having improved light efficiency by reducing a distance between a light diffusion member and a 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 a circuit board, a plurality of reflection members disposed on the light emitting diode chip, and a light diffusion member. The light diffusion member has an incident surface on which light is incident and an exit surface on which light is emitted, and is disposed on an upper portion of the circuit substrate. The plurality of reflective members are stacked on each other and reflect a part of the light emitted from the upper surface of the light emitting diode chip. Further, the incident surface of the light diffusion member covers the side surface of the light emitting diode chip, the side surface of the reflecting member, and the upper surface of the reflecting member.

The backlight unit according to the embodiment of the present invention can reduce the thickness by forming a cavity in the light diffusion member and arranging the light emitting diode chip in the cavity of the light diffusion member.

The backlight unit according to the embodiment of the present invention can uniformly place the light emitting diode chip on the entire light diffusing member, so that the local dimming is possible in addition to the thickness reduction.

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like numbers refer to like elements throughout the specification and like reference numerals represent corresponding like 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 reflection members disposed on the light emitting diode chip, and a light diffusion member. The light diffusion member has an incident surface on which light is incident and an exit surface on which light is emitted, and is disposed on the circuit substrate. The plurality of reflection members are stacked on each other and reflect a part of the light emitted from the upper surface of the LED chip. Further, the incident surface of the light diffusion member covers the side surface of the light emitting diode chip, the side surface of the reflecting member, and the top surface of the reflecting member.

The plurality of reflective members may have different areas. For example, the plurality of reflective members are positioned with a reflective member having a small area as the distance from the top surface of the LED chip is large.

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

At least one of the plurality of reflecting members may be different in material from the other reflecting members.

Further, at least one of the plurality of reflecting members may have a thickness different from that of the other reflecting member.

The plurality of reflecting members may be a light transmitting resin containing a reflecting material.

According to an embodiment, the light 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 reflecting member, and an upper surface of the reflecting member.

The backlight unit may further include a wavelength conversion member.

For example, the wavelength conversion member may cover the side surface and the upper surface of the light emitting diode chip. At this time, the incident surface of the light diffusing member may be in close contact with the side surface of the wavelength converting member, the side surface of the reflecting member, and the top surface of the reflecting member.

Or the wavelength converting member may cover the side surface of the light emitting diode chip, the side surface of the reflecting member, and the top surface of the reflecting member. At this time, the incident surface of the light diffusion member may be in close contact with the side surface and the upper surface of the wavelength conversion member.

The light exit surface of the light diffusing member may be flat.

Alternatively, the light exit surface of the light diffusing member may further include a convex portion convex upward. At this time, the convex portion is located on each of the LED chips.

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

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

According to another embodiment, the incident surface of the light diffusing member may be spaced apart from a side surface of the light emitting diode chip, a side surface of the reflecting member, and an upper surface of the reflecting member.

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

The backlight unit may further include a reflective sheet disposed under the light diffusion member.

The backlight unit may further include a light diffusion material dispersed in the light diffusion member.

The backlight unit may further include a diffusion sheet disposed on the light diffusion member.

The backlight unit may further include a wavelength conversion sheet disposed on the light diffusion member.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 3 are views showing an example of a backlight unit according to a first embodiment of the present invention.

1 is a top plan view schematically showing a backlight unit 100 according to the first embodiment. 2 shows the backlight unit 100 in a state where the light diffusion member 110 and the LED chip 130 are separated from each other, and FIG. 3 is a sectional view of FIG.

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 acrylic resin such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), and polyethylene naphthalate (PEN) resin.

According to the 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 is not structured to penetrate to the upper surface. The cavity 111 has a structure corresponding to the outer shape of the light emitting diode chip 130 and the reflective member 140 disposed inside the light diffusion member 110.

The light emitting diode chip 130 and the reflecting member 140 disposed on the upper surface of the LED chip 130 are accommodated in the cavity 111 of the light diffusion member 110.

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

A circuit board 120 on which the 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 to supply power to the light emitting diode chip 130 to emit light.

Referring to this embodiment, the upper surface of the light diffusing member 110 includes the convex portion 113. The convex portion 113 is a convex portion upward in the upper surface of the light diffusion member 110. For example, the convex portion 113 has a hemispherical structure. The convex portion 113 is positioned on the upper portion of the light emitting diode chip 130. 3, the convex portion 113 surrounds the side surface and the upper surface of the light emitting diode chip 130. As shown in FIG. Further, the convex portion 113 is formed so as to surround each of the plurality of light emitting diode chips 130. The inner surface of the light diffusion member 113 constituting the cavity 111 is an incident surface on which the light of the LED chip 120 is incident. The upper surface of the light diffusion member 113 is an emission surface through which light is emitted to the outside.

The exit surface of the light diffusion member 110 is a curved surface that forms a plane and a 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 the present embodiment, the light emitted from the LED chip 130 is refracted while being diffused through the incident surface of the concave structure into the inside of the light diffusion member 110, and spreads and is primarily scattered. When the light incident on the light diffusion member 110 is emitted to the outside of the light diffusion member 110, the light is refracted by the structure of the convex portion 113 to be secondarily scattered. That is, light is uniformly spread to the upper portion of the light diffusion member 110 by the structure of the incident surface concaved in the light diffusion member 110 and the convex portion 113 convex upward. Light emitted from each of the convex portions 113 can be crossed in a space between adjacent convex portions 113 because the light is emitted while being evenly spread in the convex portions 113. [ Accordingly, the backlight unit 100 according to the present embodiment includes the light diffusion member 110 including the incident surface having the concave inner surface and the emitting surface having the convex portion 113, and the space between the light emitting diode chips 130 It is possible to prevent occurrence of a dark spot on the upper part.

In addition, since the light-diffusing member 110 has the curvature of the exit surface by the convex portion 113, the phenomenon that light is totally reflected on the exit surface can be reduced. Since the total reflection of light is reduced in the backlight unit 100 of the present embodiment, the light extraction efficiency is improved. The light emitting diode chip 130 is mounted on the circuit board 120 and is positioned in the cavity 111 of the light diffusion member 110. The light emitting diode chip 130 may be disposed in each of the cavities 111 if the plurality of cavities 111 are formed in the light diffusion member 110. [

According to the embodiment of the present invention, the light emitting diode chip 130 emits light through the top surface and the side surface. 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 incident surface which is the inner surface of the cavity 111 of the light diffusion member 110. The light emitted from the side surface of the light emitting diode chip 130 is directly incident on the incident surface of the light diffusion member 110. The light emitted from the side surface of the light emitting diode chip 130 is generated in the active layer of the light emitting diode chip 130 and passes through the side surface of the light emitting diode chip 130, And then passes through the side surface of the light emitting diode chip 130.

On the upper surface of the light emitting diode chip 130, a single layer or a plurality of reflective members 140 are formed. For example, a first reflective member 141 to a third reflective member 143 are sequentially stacked on the upper surface of the LED chip 130.

According to the present embodiment, a second reflective member 142 having a smaller area 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 LED chip 130. At this time, the second reflecting member 142 is located in the region of the first reflecting member 141. A third reflective member 143 having a smaller area than the second reflective member 142 is disposed on the second reflective member 142. At this time, the third reflecting member 143 is located in the region of the second reflecting member 142.

The first reflection member 141 to the third reflection member 143 formed as described above reflect a part of the light that has passed through the upper surface of the light emitting diode chip 130 and form a cavity 111 as an incident surface of the light diffusion member 110 So that it can be incident on the inner surface.

In this embodiment, the upper surface and the side surface of the reflective member 140 are in close contact with the inner surface constituting the cavity 111 of the light diffusion member 110. The light that has passed through the reflective member 140 is incident on the inner surface of the light diffusion member 110 which is in close contact with the reflective member 140.

The light emitted from the side surface of the light emitting diode chip 130 and the light emitted from the first reflection member 141 to the third reflection member 140 may be incident on the inner side surface of the light diffusion member 110 which is in close contact with the side surface of the light emitting diode chip 130, The light reflected by the member 143 is incident. The light passing through the reflective member 140 is incident on the upper surface of the inner surface of the light emitting diode chip 130, which is in close contact with the reflective member 140 except the inner surface.

The light reflectance of the first to third reflective members 141 to 143 may vary depending on the material, thickness, area, and the like. Therefore, the amount of light directed toward the inner side surface of the light diffusion member 110 can be adjusted by adjusting the light reflectance of the first reflection member 141 and the third reflection member 143. The inner surface of the light diffusion member 110 is a portion of the light diffusion member 110 which is in close contact with the side surface of the LED chip 130 and is in contact with the side surface of the first reflection member 141. The light reflected from the upper surface of the light diffusion member 110 through the inner side surface of the light diffusion member 110 is adjusted by adjusting the light reflectance of the first reflection member 141 and the third reflection member 143, The ratio of the light emitted from the upper surface of the light diffusion member 110 through the inner upper surface of the light diffusion member 110 can be adjusted. The ratio of the 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 by using the reflection member 140 so that the emission of the light diffusion member 110 The light uniformity of the entire surface can be controlled.

The first reflection member 141 to the third reflection member 143 may be formed of any material capable of reflecting at least a part of light. The first reflection member 141 to the third reflection member 143 may be DBR (Distributed Bragg Reflector). For example, the DBR can be made up 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 layers of SiO ₂ , TiO ₂ , SiN, and TiN are stacked once or repeatedly. Alternatively, the first reflection member 141 to the third reflection member 143 may be made of a metal such as Ag or Al. Or some of the first to third reflective members 141 to 143 may be made of metal, and the other reflective member may be made of DBR. In the embodiment of the present invention, the structure in which the reflecting member has three layers is described as an example, but the number of reflecting members can be changed depending on the thickness, material, and light amount control of the reflecting member.

In the light emitting device 100 according to the present embodiment, the light diffusion member 110 and the light emitting diode chip 130 and the reflection member 140, which emit light, are in close contact with each other. Therefore, 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 the other medium.

The light diffusion member 110 may be formed by an injection molding method. The light diffusion member 110 is formed by injecting the material of the light diffusion member into a mold designed to have a cavity 111 having an inner surface corresponding to the structure of the light emitting diode chip 130 and the reflection member 140, . 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. In this case, since the cavity 111 is formed in a structure corresponding to the light emitting diode chip 130 and the reflecting member 140, the light emitting diode chip 130 and the reflecting member 140 Can be fixed.

The conventional edge type backlight unit has a limitation in thinning the bezel of the display device because the light emitting diode chip is disposed along the side surface of the light diffusing member. Further, the edge type backlight unit generally has a problem that a plurality of light emitting diode chips mounted on a circuit board are connected in series and can not be individually operated.

In addition, since the conventional direct type backlight unit has a light emitting diode chip disposed under the light diffusing member, there is a limitation in reducing the thickness of the backlight unit and the display device.

However, in the backlight unit 100 according to the embodiment of the present invention, the light emitting diode chip 130 is not positioned below the light diffusion member 110 but is positioned inside the light diffusion member 110 through the cavity 111 The thickness of the backlight unit 100 and the display device can be reduced. In addition, the backlight unit 100 according to the embodiment of the present invention can implement local dimming in which the light emitting diode chips 130 are individually controlled through the circuit board 120. In addition, according to the 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. Therefore, the backlight unit 100 of the present embodiment can easily control the light necessary to make the uniformity of the light emitted through the upper surface of the light diffusion member 110 and the light emitted to the upper portion of the cavity 1110 be 90% or more. Furthermore, since the backlight unit 100 can emit light uniformly, it is possible to minimize the smearing phenomenon of the display device (not shown) to which the backlight unit 100 is applied.

In the backlight unit 100 of the present embodiment, the surface of the light emitting diode chip 130 on which light is emitted and 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 prevents light loss due to a distance between a light emitting surface and an incident surface of the light diffusing member 110 and light reflection at an interface between different media, 110 can be improved.

4 is an exemplary view showing a light emitting diode chip and a reflecting member according to the first embodiment.

The light emitting diode chip 10 of this embodiment is an embodiment of the light emitting diode chip of the backlight unit (100 of Figs. 1 to 3). The light emitting diode chip 10 of this embodiment is a horizontal structure in which both electrodes of both polarities are formed in the lower part.

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, . ≪ / RTI >

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. In addition, 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 under the substrate 11. The light emitting structure 12 includes an active layer 13 interposed between the first conductivity type semiconductor layer 13 and the second conductivity type semiconductor layer 15 and between the first conductivity type semiconductor layer 13 and the second conductivity type semiconductor layer 15, (14). Here, the first conductivity type and the second conductivity type may be opposite to each other, the first conductivity type may be n-type, 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 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. Or at least one of the first conductivity type semiconductor layer 13 and the second conductivity type semiconductor layer 15 may have a multi-layer structure. The active layer 14 may be formed of a single quantum well or a multiple quantum well structure. Although not shown in FIG. 4, a buffer layer may be formed between the substrate 11 and the first conductivity type 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 techniques. The second conductivity type semiconductor layer 15 and the active layer 14 may be patterned to expose a part of the first conductivity type semiconductor layer 13 by a photolithography and etching process. At this time, a part of the first conductivity type semiconductor layer 13 may also be patterned.

The transparent electrode layer 16 is disposed on the bottom surface of the second conductivity type 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 a lower resistivity than the second conductivity type semiconductor layer 15 and can disperse the current.

The first electrode pad 17 is disposed under the first conductivity type 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 conductivity type 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 except for the first electrode pad 17 and the second electrode pad 18. The reflective layer 19 is formed to cover the side surfaces of the active layer 14 and the second conductivity type semiconductor layer 15 exposed by patterning to expose the first conductivity type semiconductor layer 13.

The reflective layer 19 thus formed reflects light generated in the active layer 14 and proceeds toward the second electrode pad 18 so as to face the upper side or the side surface of the LED chip 10. Therefore, all the light generated in the light emitting structure 12 can be emitted only from the light emitting surface.

The reflective layer 19 may be a metal layer surrounded by an insulating layer or insulating layer made of a single layer or a multi-layer DBR. The position and structure in which the reflective layer 19 is formed are not limited to the structure shown in FIG. The position and structure of the reflective layer 19 can be variously changed if the reflective layer 19 can reflect light toward the second electrode pad 18.

The first reflective member 141 to the third reflective member 143 are disposed on the upper surface of the LED chip 10.

The first reflecting 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 reflection member 141 is formed to have a smaller area than the substrate 11, the amount of light emitted through the other portion or the light diffusion member is larger than the amount of light emitted through the other portion or the light diffusion member. There can be a difference.

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

The third reflecting member 143 is disposed on the upper surface of the second reflecting member 142. The third reflecting member 143 has an area smaller than that of the second reflecting member 142.

Light directed to the upper portion of the light emitting diode chip 10 is partially reflected by the first reflection member 141 and the other part is transmitted through the first reflection member 141. At this time, a part of the light having passed through the first reflection member 141 is emitted to the outside, and the other part is directed to the second reflection member 142. The light from the first reflecting member 141 toward the second reflecting member 142 is partially reflected by the second reflecting member 142 while the other portion passes through the second reflecting member 142. [ At this time, a 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. The light from the second reflecting member 142 toward the third reflecting member 143 is partially reflected by the third reflecting member 143 and the other part passes through the third reflecting member 143. [ As described above, light emitted from the upper portion of the light emitting diode chip 10 through the first reflective member 141 to the third reflective member 143 having different areas is emitted through the side surface of the LED chip 10 The amount of light can be adjusted.

In addition, when the reflective member disposed on the upper surface of the LED chip 10 is formed as a multi-layer structure that does not have a single layer but has a gradually reduced area, the reflectance can be adjusted by using the material and thickness of each layer, This is possible.

Although not shown in the embodiment of the present invention, an ohmic contact (not shown) is formed between the first conductivity type semiconductor layer 13 and the first electrode pad 17 and between the second conductivity type semiconductor layer 15 and the second electrode pad 18 An ohmic contact layer for ohmic contact may be located.

5 is an exemplary view illustrating 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 of Figs. 1 to 3). The light emitting diode chip 20 of this embodiment is a vertical structure in which one electrode is formed on each of the upper and lower sides.

In the description of the light emitting diode chip 20 according to the second embodiment, description of the same components as those of the light emitting diode chip 10 according to the first embodiment (10 in FIG. 4) will be omitted. The omitted description will be described with reference 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 may serve not only to support the light emitting structure 12 but also to serve as a second electrode pad by being electrically connected to the second conductive type semiconductor layer 15.

The light emitting structure 12 is located on the conductive substrate 21. The light emitting structure 12 has a structure in which the second conductivity type semiconductor layer 15, the active layer 14 and the first conductivity type 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 type semiconductor layer 15 to reflect light emitted from the active layer 14 toward 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 type semiconductor layer 15. The reflective layer 22 may also serve as an ohmic contact layer between the conductive substrate 21 and the second conductivity type semiconductor layer 15.

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

The first reflective member 141 to the third reflective member 143 may be formed on the first conductivity type semiconductor layer 13 except for the portion where the first electrode pad 17 is formed.

The first reflection member 141 to the third reflection member 143 may be DBRs. If the first reflecting member 141 and the third reflecting member 143 are formed of a metal, an insulating layer for insulating the first electrode pad 17 and the first conductive type semiconductor layer 13 is further formed . Or 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.

As described above, it is easy to control the amount of light emitted from the top and side surfaces of the light emitting diode chip 20 by the first reflecting member 141 to the third reflecting member 143. 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. Therefore, it is possible to control the position and the amount of light emitted from the light emitting diode chip 20, while simplifying the structure.

4 and 5, an example in which the reflection member 140 is formed on the light emitting diode chip having the horizontal structure and the 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 FIG. 4 and FIG. The light-emitting diode chip can be any light-emitting diode chip capable of wire bonding and flip chip bonding. Also, the reflective member 140 may be formed in any portion of the light emitting diode chip 130 where light amount control is required.

Further, the light emitting diode chip of various structures to which the reflecting member 140 is applied can be applied to other embodiments of the backlight unit thereafter.

Hereinafter, when explaining the various embodiments, portions already described in the previous embodiments will be omitted or briefly described. Therefore, a detailed description of the configuration in which the briefly described configuration and explanation are omitted will be referred to the previous embodiment.

6 is an exemplary view illustrating a backlight unit according to a second embodiment of the present invention.

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, .

The backlight unit 200 of this embodiment includes a light emitting diode chip 130 and a wavelength converting member 210 surrounding the reflecting member 140. At this time, the inner surface of the light diffusion member 110 constituting 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. Thus, the wavelength-converted light emitted through the wavelength converting member 210 is directly incident on the light diffusing member 110.

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

The wavelength conversion member 210 may be a mixture of phosphors for converting the wavelength of light into a transparent resin. For example, the transparent resin may be a transparent silicone (Silicone). As the fluorescent material, a yellow fluorescent material, a red fluorescent material, a green fluorescent material, or the like can be used.

Examples of the yellow phosphor include YAG: Ce (T ₃ Al ₅ O ₁₂ : Ce) -based phosphor or silicate (YAG), which is a yttrium (Y) aluminum (Al) garnet doped with Ce having a wavelength of 530 to 570 nm as a main wavelength ) Series phosphors.

Examples of the red (R) phosphors include YOX (Y ₂ O ₃ : EU) phosphors or nitride phosphors composed of yttrium oxide (Y ₂ O ₃ ) and europium (EU) .

Examples of the green (G) phosphor include phosphors of phosphoric acid (PO ₄ ) having a main wavelength of 544 nm and LAP (LaPO ₄ : Ce, Tb) series of compounds of lanthanum (La) and terbium (Tb).

Examples of blue (B) phosphors include barium (Ba), magnesium (Mg) and aluminum oxide based materials having a main wavelength of 450 nm, and BAM (BaMgAl ₁₀ O ₁₇ : Eu) based compounds of europium And a phosphor.

Further, the phosphor may include a fluoride compound KSF phosphor (K ₂ SiF ₆ ) which is a Mn 4+ activator phosphor favorable for high color reproduction.

The wavelength converting member 210 surrounding the light emitting diode chip 130 and the reflecting member 140 can reflect the light emitted from the side surface of the light emitting diode chip 130 and the light passing through the reflecting member 140 All can be converted.

7 is an exemplary view illustrating a backlight unit according to a third embodiment of the present invention.

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, .

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 so as to surround the side surface and the upper surface 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. The inner surface of the light diffusion member 110 is in close contact with the side surface of the wavelength conversion member 210 and the inner surface of the light diffusion member 110 is in close contact with the reflection member 140.

The light emitted from the side surface of the light emitting diode chip 130 is wavelength-converted and directed to the light diffusion member 110. The light emitted from the upper surface of the LED chip 130 is wavelength-converted and directed to the reflective member 140. That is, since the light reflected by the reflective member 140 has already been wavelength-converted on the upper surface of the light emitting diode chip 130, it is not necessary to perform wavelength conversion on the side surface of the light emitting diode chip 130. Therefore, since the wavelength converting member 210 located on the side surface of the LED chip 130 does not need to consider the light reflected by the reflecting member 140, it is not necessary to increase the phosphor content or to form a thicker layer. That is, the wavelength conversion member 210 can uniformly perform optical wavelength conversion even if the top and side thicknesses are adjusted in consideration of only the light emitted from the top and side surfaces of the LED chip 130.

8 is an exemplary view illustrating 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 reflecting member 410 may be one containing a reflecting material 411 in the light-transmitting resin. The light transmitting resin constituting the reflecting member 410 may be a known material such as a silicone resin, an epoxy resin or the like. For example, the light transmitting resin of the reflecting member 410 may be a silicone resin having a refractive index difference with respect to the light diffusing member 110 of 10% or less.

The reflective member 410 is positioned on the upper surface of the light emitting diode chip 130. Therefore, the inner surface of the light diffusion member 110 is in close contact with the side surface of the LED chip 130, the side surface of the reflective member 410, and the upper surface of the reflective member 410. The light emitted from the upper surface of the light emitting diode chip 130 passes through the light transmitting resin and can be reflected by the reflective material 411 and incident on the inner surface of the light diffusion member 110. [

The reflecting member 410 of this embodiment can control the light amount of the light that is reflected from the upper surface of the reflecting member 410 or emitted from the side surface of the light emitting diode chip 130 by adjusting the content of the reflecting material 411.

9 is a view illustrating an example of 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 the present embodiment, the light diffusion member 510 includes convex portions 513 having curved surfaces that are not spherical. For example, the convex portion 513 has a parabolic structure in which the height h of the cross section is larger than the width w of both ends.

The convex portion 513 having such a parabolic structure has different curvatures at each position where light is emitted.

Further, the convex portion 513 has a larger area than that of the hemispherical structure. In other words, the light diffusion member 510 has the emission surface having a larger area by the convex portion 513 of the parabolic structure.

For example, as the height of the cross section increases with respect to the width of the convex portion 513, the light is refracted at different angles through a wider area of the convex portion 513, so that light can be scattered more widely.

Accordingly, the light scattered at the incident surface of the light diffusion member 510 and widely spread can be emitted at different angles through a wider area by the convex portion 513 of the parabolic structure, and can be scattered more widely.

Since the backlight unit 500 according to the present embodiment diffuses light more widely in the convex portions 513 of the parabolic structure, the light emitted from the adjacent convex portions 513 and the convex portions 513 Light can be mixed better.

In addition, the backlight unit 500 according to the present embodiment can control the amount of light emitted upward in the light emitting diode chip 130 and light emitted in the lateral direction by the reflective member 140.

As described above, the convex portion 513 and the reflecting member 140 of the parabolic structure can improve the uniformity of the light emitted through the exit surface of the light diffusion member 510 by the backlight unit 500.

10 to 13 are views showing an example of 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 the present embodiment, the light diffusion member 610 has a structure in which the emission surface is flat. Accordingly, the light diffusing member 610 according to the present embodiment can be manufactured with only a simple process of planarizing the top surface without forming and having a separate structure. Or the light diffusing member having a separate structure needs to be manufactured so that the mold to which the material of the light diffusion member is injected corresponds to the structure of the light diffusion member. However, the light diffusion member 610 according to the embodiment of the present invention may be a separate mold Production is not required. In addition, since the top surface of the light diffusing member 610 according to the embodiment of the present invention is flat, it can be formed by a simple process of flattening the top surface even if it is formed of a mold of any structure.

Also, the light diffusion member 610 may be formed by a method other than an injection molding method using a metal mold.

For example, the light diffusion member 610 may be formed in the manner shown in Figs.

A light emitting diode chip 130 mounted on a circuit board 120 and a circuit board 120 and having a reflective member 140 formed thereon is prepared as shown in FIG.

Thereafter, as shown in Fig. 12, the light diffusing resin 611 is applied on the circuit board 120. Then, as shown in Fig. The light diffusion resin 611 is applied so as to cover the light emitting diode chip 130 and the reflection member 140. For example, the light-diffusing resin 611 may be a silicon resin. The light diffusing resin 611 is coated on the circuit board 120 and then cured.

Thereafter, the cured light diffusing resin 611 becomes a light diffusing member 610 having a flat top surface shown in Fig. 13 through the planarization process.

The backlight unit 600 having such a structure is simpler in manufacturing process and less cost than other light diffusion members having a separate structure in the light diffusion member 610 having a flat top surface.

In addition, in the backlight unit 600 of the present embodiment, the light-diffusing surface of the light diffusing member 610 is flat, but the incident surface is recessed internally, so that light can be scattered on the incident surface. Therefore, the backlight unit 600 can uniformly emit light over the entire region of the exit surface of the light diffusion member 610. [

14 is an exemplary view illustrating a backlight unit according to a seventh embodiment of the present invention.

14, a backlight unit 700 according to a 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 reflection member 140 ).

The housing 720 has a top open structure in which a light emitting diode chip 130, a reflective member 140, and a light diffusion member 710 are disposed. The housing 720 may be formed of a reflective material or the reflective material may be coated on the inner wall. In this case, the light emitted from the lower surface and the side surface of the light diffusion member 710 can be reflected by the inner wall of the housing 720 and re-incident on the light diffusion member 710, thereby improving the light efficiency of the backlight unit 700 . The backlight unit of another previously described embodiment also includes a housing 720. [

According to the present embodiment, the cavity 711 of the light diffusion member 710 has a rectangular cross section. The light diffusion member 710 is formed such that the cavity 711 has a larger size than the light emitting diode chip 130 and the reflection member 140. That is, the cavity 711 of the light diffusion member 710 has a width larger than the width of the light emitting diode chip 130 and is larger than the length from the lower surface of the light emitting diode chip 130 to the upper surface of the reflection member 140 .

 The backlight unit 700 of the present embodiment is configured such that the light diffusing member 710 covers the light emitting diode chip 130 and the reflecting member 140 but the incident surface of the light diffusing member 710 and the light emitting diode chip 130, And the reflective member 140 are formed.

In this embodiment, the cavity 711 of the light diffusion member 710 has a simple structure with a rectangular cross section. Therefore, the light diffusion member 710 can be easily manufactured.

Since the cavity 711 of the light diffusing member 710 is larger than the light emitting diode chip 130 and the reflecting member 140, the light emitting diode chip 130 and the reflecting member 140 are separated by the light diffusing member 710, Can be prevented from being damaged. It is possible to prevent the light diffusion member 710 from being damaged by the light emitting diode chip 130 and the reflection member 140. That is, when the light diffusion member 710 covers the light emitting diode chip 130 and the reflection 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 reflecting member 140 from being struck.

15 is an exemplary view illustrating a backlight unit according to an eighth embodiment of the present invention.

15, a backlight unit 800 according to an 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, a reflection member 140 And a sealing member 810.

According to the present embodiment, the sealing member 810 is formed between the light emitting diode chip 130 and the reflective member 140 and the light diffusion member 710. That is, the sealing member 810 is formed on the circuit board 120 so as 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 an already known transparent material such as an epoxy resin, a silicone resin, or the like. In addition, the sealing member 810 may be formed of a material having a refractive index similar to that of the light diffusion member 710. When the sealing member 810 is made of a material having a refractive index similar to that of the light diffusing member 710, light directed from the light emitting diode chip 130 to the light diffusing member 710 passes through the interface between the light diffusing member 710 and the sealing member 810 Can be minimized.

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

16, a backlight unit 900 according to a 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, a reflection 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 reflection sheet 910 may reflect the light emitted from the light emitting diode chip 130 toward the housing 720 to be incident on the light diffusion member 610. Further, the reflection sheet 910 may reflect the light emitted from the lower surface of the light diffusion member 610 to re-enter the light diffusion member 610. Therefore, the light efficiency of the backlight unit 900 of the present embodiment is improved by the reflective sheet 910. [

Although the reflective sheet 910 is disposed on the upper surface of the circuit board 120 in this embodiment, the position of the reflective sheet 910 is not limited thereto. In the case where the circuit board 120 is a glass substrate through which light is transmitted, it is also possible that the reflection sheet 910 is disposed below the circuit board 120. In addition, when the reflective sheet 910 is disposed inside the housing 720, the housing 720 may not be a reflective material or a reflective material coated on the inner wall of the housing may be omitted.

17 is an exemplary view illustrating a backlight unit according to a tenth embodiment of the present invention.

17, a backlight unit 1000 according to a 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 reflection member 140 ).

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

The backlight unit 1000 according to the present embodiment can improve the uniformity of light emitted from the light diffusion member 1010 because the light diffusion material 1020 is dispersed in the light diffusion member 1010.

18 is an exemplary view illustrating a backlight unit according to an eleventh embodiment of the present invention.

18, a backlight unit 1100 according to an eleventh 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, 1110).

The backlight unit 1100 according to the eleventh embodiment differs from the tenth embodiment in that a structure for light diffusion is disposed in the upper part of the light diffusion member 610 rather than the inside thereof.

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

Therefore, the backlight unit 1100 according to the present embodiment can improve the uniformity of light by the diffusion sheet 1110. [

The backlight unit of the tenth embodiment and the eleventh embodiment improves the uniformity of light by using the light diffusing material dispersed inside the diffusion sheet or the light diffusion member. However, the structure for diffusing light is not limited thereto. The backlight unit may have a light diffusion member in which a pattern for light diffusion is formed on at least one of the upper surface and the lower surface in place of the light diffusion material and the diffusion sheet. Further, the backlight unit may include a structure for diffusing at least two of light diffusion material dispersed inside the light diffusion member, light diffusion pattern formed on the surface of the light diffusion member, and diffusion sheet.

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

19, a backlight unit 1200 according to a 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, a reflection member 140 And a wavelength conversion sheet 1210.

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

It is possible to omit the wavelength conversion member formed in each of the plurality of light emitting diode chips 130 by the wavelength conversion sheet 1210 disposed on the top of the light diffusion member 610. [

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

The light diffusing material, the light diffusion pattern, and the optical sheet of the backlight unit of the seventh to twelfth embodiments of the present invention can be similarly applied to the backlight units of the first to sixth embodiments.

The backlight unit according to the present embodiment can efficiently improve the light uniformity by using a light diffusing material, a light diffusion pattern, an optical sheet, or the like.

Although the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It should be understood that the scope of the present invention is to be understood as the scope of the following claims and their equivalents.

11: substrate
12: light emitting structure
13: First conductive type semiconductor layer
14:
15: a second conductivity type 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,
110, 510, 610, 710, 1010:
111, 711: cavity
113, 513:
120: circuit board
10, 20, 130: light emitting diode chip
140, 410: reflective member
141: first reflection member
142: a second reflection member
143: third reflection member
150: sealing member
210: wavelength conversion member
411: Reflective material
611: light diffusing resin
720: Housing
810: Sealing member
910: reflective sheet
1020: light diffusing material
1110: diffusion sheet
1210: Wavelength conversion sheet

Claims (23)

A circuit board;
At least one light emitting diode chip mounted on the circuit board;
A plurality of reflective members disposed on the LED chip; And
And a light diffusion member having an incident surface on which light is incident and an emission surface on which light is emitted and disposed on the circuit board,
The plurality of reflective members are stacked on each other and reflect a part of the light emitted from the upper surface of the LED chip,
Wherein the incident surface of the light diffusion member covers a side surface of the light emitting diode chip, a side surface of the reflecting member, and an upper surface of the reflecting member.
The method according to claim 1,
Wherein the plurality of reflection members have different areas,
And a reflective member having a smaller area as the distance from the upper surface of the LED chip is larger.
The method according to claim 1,
Wherein the plurality of reflective members are DBRs (Distributed Bragg Reflectors).
The method according to claim 1,
Wherein the plurality of reflecting members are made of metal.
The method according to claim 1,
Wherein at least one of the plurality of reflective members is different in material from the other reflective members.
The method according to claim 1,
Wherein at least one of the plurality of reflective members is different in thickness from the other reflective member.
The method according to claim 1,
Wherein the plurality of reflective members are translucent resins containing a reflective material.
The method according to claim 1,
Wherein the light incident surface of the light diffusion member is in close contact with the side surface of the light emitting diode chip, the side surface of the reflecting member, and the top surface of the reflecting member.
The method according to claim 1,
And a wavelength conversion member covering the side surface and the upper surface of the light emitting diode chip.
The method of claim 9,
Wherein the incident surface of the light diffusing member is in close contact with a side surface of the wavelength converting member, a side surface of the reflecting member, and an upper surface of the reflecting member.
The method according to claim 1,
Further comprising a wavelength converting member covering a side surface of the light emitting diode chip, a side surface of the reflecting member, and an upper surface of the reflecting member.
The method of claim 11,
Wherein the incident surface of the light diffusing member is in close contact with a side surface and an upper surface of the wavelength converting member.
The method according to claim 1,
And the exit surface of the light diffusion member is flat.
14. The method of claim 13,
And the exit surface of the light diffusion member further includes a convex portion convex upward.
15. The method of claim 14,
And the convex portion is located on each of the light emitting diode chips.
The method according to claim 1,
Wherein the curvatures of the light incident surface and the light exit surface of the light diffusion member are different from each other.
The method according to claim 1,
Wherein a refractive index of the light-diffusing member is different from that of the light-incident surface of the light-diffusing member.
The method according to claim 1,
Wherein the light incident surface of the light diffusing member is spaced apart from a side surface of the light emitting diode chip, a side surface of the reflecting member, and an upper surface of the reflecting member.
The method according to claim 1,
And a sealing member disposed between the light emitting diode chip and the incident surface of the light diffusing member.
The method according to claim 1,
And a reflective sheet disposed under the light diffusion member.
The method according to claim 1,
And a light diffusing material dispersed inside the light diffusing member.
The method according to claim 1,
And a diffusion sheet disposed on the light diffusion member.
The method according to claim 1,
And a wavelength conversion sheet disposed on the light diffusion member.

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