KR102446576B1 - Back light unit - Google Patents

Abstract

The present invention relates to a backlight unit. A backlight unit according to an embodiment of the present invention includes a light guide plate, a circuit board, a light emitting diode chip, a reflective member, and a sealing member. The light guide plate has at least one opening penetrating from the upper surface to the lower surface. The circuit board is disposed under the light guide plate. The light emitting diode chip is mounted on a circuit board and disposed in an opening of the light guide plate. The reflective member is formed on the upper surface of the light emitting diode chip. The sealing member is positioned between at least a side surface of the light emitting diode chip and an inner wall of the opening of the light guide plate. Here, the reflective member reflects a portion of the light emitted from the upper surface of the light emitting diode chip toward the inner wall of the opening, which is the incident surface of the light guide plate. Also, in the backlight unit, the uniformity of light emitted from the upper surface of the light guide plate and light emitted from the upper portion of the opening of the light guide plate is 90% or more.

Description

backlight unit {BACK LIGHT UNIT}

The present invention relates to a backlight unit.

A display device, which is a light-receiving device without a self-luminous source, requires a separate light source device capable of illuminating the entire screen from the rear side. A lighting device for such a display device is generally referred to as a backlight unit.

In general, the backlight unit is classified into an edge type and a direct type according to a method in which a light source emitting light, such as an LED chip, is arranged.

The edge type backlight unit is a method in which a light source is disposed on a side surface of a light guide plate 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 guide plate. In addition, the edge type backlight unit generally has a problem in that a plurality of light emitting diode chips mounted on a circuit board are connected in series and thus cannot be operated individually.

The direct backlight unit illuminates the entire surface of the display panel by arranging a light source under the light guide plate. However, in the direct backlight unit, since the light emitting diode chip is disposed under the light guide plate, there is a limitation in reducing the thickness of the backlight unit and the display device.

SUMMARY OF THE INVENTION An object of the present invention is 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 reducing the thickness of a display device while enabling local dimming.

Another object of the present invention is to provide a backlight unit with easy light control so that the light uniformity is 90% or more.

According to an embodiment of the present invention, a backlight unit including a light guide plate, a circuit board, a light emitting diode chip, a reflective member, and a sealing member is provided. The light guide plate has at least one opening penetrating from the upper surface to the lower surface. The circuit board is disposed under the light guide plate. The light emitting diode chip is mounted on a circuit board and disposed in an opening of the light guide plate. The reflective member is formed on the upper surface of the light emitting diode chip. The sealing member is positioned between at least a side surface of the light emitting diode chip and an inner wall of the opening of the light guide plate. Here, the reflective member reflects a portion of the light emitted from the upper surface of the light emitting diode chip toward the inner wall of the opening, which is the incident surface of the light guide plate. Also, in the backlight unit, the uniformity of light emitted from the upper surface of the light guide plate and light emitted from the upper portion of the opening of the light guide plate is 90% or more.

In the backlight unit according to an embodiment of the present invention, an opening is formed in the light guide plate, and the light emitting diode chip is disposed in the opening of the light guide plate, so that the thickness can be reduced.

In the backlight unit according to an embodiment of the present invention, the light emitting diode chip may be evenly disposed on the entire light guide plate, so that the thickness can be reduced and local dimming is possible.

In the backlight unit according to an embodiment of the present invention, it is easy to control the light so that the uniformity of the light emitted from the upper surface of the light guide plate and the light emitted from the upper portion of the opening of the light guide plate is 90% or more. Since the backlight unit can be controlled so that the light uniformity is 90% or more, it is possible to minimize the unevenness of the display device to which the backlight unit is applied.

1 and 2 are exemplary views illustrating a backlight unit according to a first embodiment of the present invention.
3 is an exemplary view illustrating a light emitting diode chip and a reflective member according to the first embodiment.
4 is an exemplary view illustrating a light emitting diode chip and a reflective member according to a second embodiment.
5 is an exemplary view illustrating a backlight unit according to a second embodiment of the present invention.
6 is an exemplary view illustrating a backlight unit according to a third embodiment of the present invention.
7 is an exemplary view illustrating a backlight unit according to a fourth embodiment of the present invention.
8 is an exemplary view illustrating a backlight unit according to a fifth embodiment of the present invention.
9 is an exemplary view illustrating a backlight unit according to a sixth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples so that the spirit 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 the components may be exaggerated for convenience. Throughout the specification, like reference numbers refer to like elements and like reference numbers refer to corresponding like elements.

A backlight unit according to an embodiment of the present invention includes a light guide plate, a circuit board, a light emitting diode chip, a reflective member, and a sealing member. The light guide plate has at least one opening penetrating from the upper surface to the lower surface. The circuit board is disposed under the light guide plate. The light emitting diode chip is mounted on the circuit board and disposed in the opening of the light guide plate. The reflective member is formed on the upper surface of the light emitting diode chip. The sealing member is positioned between at least a side surface of the light emitting diode chip and an inner wall of the opening of the light guide plate. Here, the reflective member reflects a portion of the light emitted from the upper surface of the light emitting diode chip toward the inner wall of the opening, which is the incident surface of the light guide plate. Also, in the backlight unit, the uniformity of light emitted from the upper surface of the light guide plate and light emitted from the upper portion of the opening of the light guide plate is 90% or more.

According to an embodiment, the reflective member may include a plurality of reflective members having different areas. In addition, the reflective member having a smaller area is positioned as it moves away from the upper surface of the light emitting diode chip.

The reflective member may be formed of a distributed Bragg reflector (DBR). For example, the reflective member is made of at least one of SiO2, TiO2, SiN, and TiN.

Alternatively, the reflective member may be made of metal. For example, the reflective member is made of at least one of Al and Ag.

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

At least one reflective member of the plurality of reflective members may have a thickness different from that of other reflective members.

The sealing member may have a refractive index difference of 10% or less from the light guide plate.

The sealing member may further contain a phosphor.

According to another embodiment, the reflective member may be a light-transmitting resin containing a reflective material.

The sealing member may fill a gap between a side surface of the light emitting diode chip and an inner wall of the opening of the light guide plate. In this case, the reflective member may fill an upper portion of the light emitting diode chip and an upper portion of the sealing member in the opening of the light guide plate.

In addition, the reflective member may further contain a phosphor.

A difference in refractive index between the light-transmitting resin of the reflective member and the light guide plate may be 10% or less.

The backlight unit may further include a wavelength conversion member formed to surround side surfaces and upper surfaces of the light emitting diode chip. In this case, the reflective member may be positioned above the wavelength conversion member.

Alternatively, the backlight unit may further include a wavelength conversion member formed to surround a side surface of the light emitting diode chip, a side surface of the reflection member, and an upper surface of the reflection member.

The incident surface of the light guide plate has an inclination such that the width of the opening becomes narrower from the lower part to the upper part.

The upper surface of the light guide plate is positioned on the same line as or higher than the upper surface of the reflective member.

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

1 and 2 are exemplary views illustrating a backlight unit according to a first embodiment of the present invention.

1 is a plan view schematically illustrating a backlight unit 100 according to a first embodiment. Also, FIG. 2 is a cross-sectional view of FIG. 1 .

Referring to FIG. 1 , the backlight unit 100 according to the first embodiment includes a light guide plate 110 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 140 , and a sealing member 150 . .

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

According to an embodiment of the present invention, the light guide plate 110 has at least one opening 111 penetrating the upper and lower surfaces. The plurality of openings 111 are arranged to have regular intervals throughout the light guide plate 110 .

The light emitting diode chip 130 and the reflective member 140 disposed on the upper surface of the light emitting diode chip 130 are accommodated in the opening 111 of the light guide plate 110 . That is, the height of the upper surface of the light guide plate 110 is positioned on the same line or higher than the upper surface of the reflective member 140 .

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

A circuit board 120 on which a light emitting diode chip 130 is mounted is disposed under the light guide plate 110 . The circuit board 120 is electrically connected to the light emitting diode chip 130 to supply power so that the light emitting diode chip 130 emits light.

The light emitting diode chip 130 is mounted on the circuit board 120 and is positioned in the opening 111 of the light guide plate 110 . If a plurality of openings 111 are formed in the light guide plate 110 , the light emitting diode chip 130 may be disposed in each of the openings 111 .

According to an embodiment of the present invention, the light emitting diode chip 130 has a structure for emitting light through the upper surface and the side surface. A detailed structure of the light emitting diode chip 130 will be described in detail later.

The side surface of the light emitting diode chip 130 faces the inner wall of the opening 111 of the light guide plate 110 . Accordingly, the light emitted from the side surface of the light emitting diode chip 130 is incident on the inner wall of the opening 111 of the light guide plate 110 . That is, the inner wall of the opening 111 of the light guide plate 110 is an incident surface on which light is incident. Here, the light emitted from the side surface of the light emitting diode chip 130 means light generated in the active layer (not shown) of the light emitting diode chip 130 and passed through the side surface of the light emitting diode chip 130 .

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

According to the present exemplary embodiment, the 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 light emitting diode chip 130 . In this case, the second reflective member 142 is positioned within the area of the first reflective member 141 . Also, a third reflective member 143 having a smaller area than the second reflective member 142 is disposed on the second reflective member 142 . In this case, the third reflective member 143 is positioned within the area of the second reflective member 142 .

The first reflective member 141 to the third reflective member 143 formed as described above may reflect a portion of the light emitted from the upper surface of the light emitting diode chip 130 toward the inner wall of the opening 111 of the light guide plate 110 . have. Here, the light emitted from the upper surface of the light emitting diode chip 130 means light generated in the active layer (not shown) of the light emitting diode chip 130 and passed through the upper surface of the light emitting diode chip 130 . Accordingly, the light emitted from the side surface of the light emitting diode chip 130 and the light reflected by the first reflecting member 141 to the third reflecting member 143 are incident on the inner wall of the opening 111 of the light guide plate 110 . .

The light reflectance of the first reflective member 141 to the third reflective member 143 may vary according to a material, thickness, area, or the like. Accordingly, the amount of light directed toward the inner wall of the opening 111 of the light guide plate 110 may be adjusted by adjusting the light reflectance of the first reflective member 141 and the third reflective member 143 . Furthermore, the light emitted from the upper surface of the light guide plate 110 through the interior of the light guide plate 110 by adjusting the light reflectivity of the first reflecting member 141 and the third reflecting member 143 and the opening of the light guide plate 110 . The rate of emitted light can be adjusted. For example, in the backlight unit 100 of the present invention, the light emitted through the upper surface of the light guide plate 110 through the first reflective member 141 to the third reflective member 143 and the opening 111 of the light guide plate 110 . ), the uniformity of the emitted light may be 90% or more.

The first reflective member 141 to the third reflective member 143 may be formed of any material capable of reflecting at least a portion of light. The first reflective member 141 to the third reflective member 143 may be formed of a distributed Bragg reflector (DBR). For example, the DBR may be formed of one layer of one of SiO2, TiO2, SiN, and TiN. Alternatively, the DBR may have a structure in which at least two of the respective layers made of SiO2, TiO2, SiN, and TiN are stacked once or repeatedly. Alternatively, the first reflective member 141 to the third reflective member 143 may be formed of a metal such as Ag or Al. Alternatively, some of the reflective members of the first reflective member 141 to the third reflective member 143 may be made of metal, and other reflective members may be made of DBR. In the exemplary embodiment of the present invention, a structure in which the reflective member has three layers is described as an example, but the number of layers of the reflective member may be changed according to the thickness, material, and control of the amount of light of the reflective member.

The sealing member 150 fills the opening 111 of the light guide plate 110 to cover the light emitting diode chip 130 . In this case, the upper surface of the sealing member 150 and the upper surface of the light guide plate 110 may be positioned on the same line.

Since the sealing member 150 surrounds the light emitting diode chip 130 , it is possible to protect the light emitting diode chip 130 from external substances such as moisture and dust. In addition, the sealing member 150 may protect the light emitting diode chip 130 from external impact. The sealing member 150 may be formed of a known light-transmitting material such as an epoxy resin or a silicone resin. Furthermore, the sealing member 150 may be formed of a material having a refractive index similar to that of the light guide plate 110 . That is, the sealing member 150 is light-transmitting, and may be formed of a material having a refractive index of 10% or less as the light guide plate 110 . For example, the light guide plate 110 may be made of PMMA, and the refractive index of PMMA is about 1.49. In this case, the sealing member 150 may be made of a light-transmitting silicone resin having a refractive index of about 1.4 to 1.6. If the sealing member 150 has a refractive index similar to that of the light guide plate 110 , it is possible to minimize reflection of light directed to the light guide plate 110 at the interface between the light guide plate 110 and the sealing member 150 .

For example, the light guide plate 110 may be formed by injection molding. The light guide plate 110 may be formed by injecting the light guide plate material into a mold designed to have the opening 111 passing therethrough and then pressing the light guide plate material. The injection-molded light guide plate 110 is disposed on the circuit board 110 so that the light emitting diode chip 130 is positioned in the opening 111 . Thereafter, the backlight unit 100 may be formed by filling the sealing member 150 in the opening 111 . The manufacturing method of the backlight unit 100 is not limited thereto, and may be formed in various ways.

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 guide plate. In addition, the edge type backlight unit generally has a problem in that a plurality of light emitting diode chips mounted on a circuit board are connected in series and thus cannot be operated individually.

In addition, since the conventional direct backlight unit has a light emitting diode chip disposed under the light guide plate, there is a limitation in 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, since the light emitting diode chip 130 is not located under the light guide plate 110, but is located inside the light guide plate 110 through the opening 111, the backlight unit ( 100) and the thickness of the display device may be reduced. In addition, the backlight unit 100 according to an embodiment of the present invention may implement local dimming for individually controlling the light emitting diode chip 130 through the circuit board 120 . In addition, according to an embodiment of the present invention, the backlight unit 100 can easily control the light reflectivity of the reflective member 140 by using the size, number of layers, and material of the reflective member 140 . Accordingly, in the backlight unit 100 according to the present embodiment, it is easy to control the light required so that the uniformity of the light emitted through the upper surface of the light guide plate 110 and the light emitted through the upper portion of the opening 1110 is 90% or more. Furthermore, since the backlight unit 100 may uniformly emit light, it is possible to minimize a stain phenomenon of a display device (not shown) to which the backlight unit 100 is applied.

3 is an exemplary view illustrating 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 embodiment of the light emitting diode chip (130 of FIG. 2 ) of the backlight unit (100 of FIGS. 1 and 2 ). 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. 3 , 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. 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 a first conductivity type semiconductor layer 13 , a second conductivity type semiconductor layer 15 , and an active layer interposed 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 are opposite to each other, and the first conductivity type may be an n-type, and the second conductivity type may be a p-type, or vice versa.

The first conductivity-type semiconductor layer 13 , the active layer 14 , and the second conductivity-type semiconductor layer 15 may be formed of a gallium nitride-based compound semiconductor material. The first conductivity type semiconductor layer 13 and the second conductivity type semiconductor layer 15 may be formed as a single layer as shown in FIG. 3 . 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. 3 , 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 technology. In addition, the second conductivity-type semiconductor layer 15 and the active layer 14 may be patterned to expose a partial region of the first conductivity-type semiconductor layer 13 through photolithography and etching processes. In this case, a portion of the first conductivity type semiconductor layer 13 may also be patterned.

The transparent electrode layer 16 is disposed on the lower 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 specific resistance than the second conductivity type semiconductor layer 15 , so that the current can be dispersed.

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 . In addition, the reflective layer 19 is formed to cover side surfaces of the active layer 14 and the second conductivity type semiconductor layer 15 exposed by patterning for exposing the first conductivity type semiconductor layer 13 .

The reflective layer 19 formed in this way reflects light generated in the active layer 14 and traveling in the direction of the second electrode pad 18 so as to be directed toward the top or side of the light emitting diode chip 10 . Accordingly, all of the light generated by the light emitting structure 12 may 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 in which the reflective layer 19 is formed is not limited to the structure shown in FIG. 3 . The position and structure of the reflective layer 19 may be variously changed as long as it can reflect light directed to the second electrode pad 18 .

A first reflective member 141 to a third reflective member 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 . In this case, 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, the light is directly emitted only from the portion of the substrate 11 exposed to the outside, and the amount of light emitted through other portions or the light guide plate is significantly different. can fly

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 .

In addition, 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 .

A portion of the light directed upward 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 . In this case, a portion of the light passing through the first reflection member 141 is emitted to the outside, and the other portion is directed toward the second reflection member 142 . Light directed from the first reflective member 141 to the second reflective member 142 is partially reflected by the second reflective member 142 , and the other part passes through the second reflective member 142 . In this case, a part of the light passing through the second reflective member 142 is emitted to the outside, and the other part is directed toward the third reflective member 143 . Light directed from the second reflective member 142 to the third reflective member 143 is partially reflected by the third reflective member 143 , and the other part passes through the third reflective member 143 . In this way, the 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 and the light emitted through the side surface 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 formed not as a single layer but as a multi-layer structure with gradually smaller areas, the reflectance is adjusted using the material and thickness of each layer, thereby more finely controlling the amount of light 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.

4 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 (130 of FIG. 2 ) of the backlight unit ( 100 in FIGS. 1 and 2 ). The light emitting diode chip 20 of this embodiment has a vertical structure in which one electrode is formed on the upper and lower portions, respectively.

In the description of the light emitting diode chip 20 according to the second embodiment, the description of the same components as the light emitting diode chip according to the first embodiment (10 of FIG. 3 ) will be omitted. For the omitted description, reference will be made to the description of FIG. 3 .

Referring to FIG. 4 , 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 be electrically connected to the second conductivity-type semiconductor layer 15 to serve as a second electrode pad.

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

A reflective layer 22 that reflects light generated in the active layer 14 and emitted toward the conductive substrate 21 may be formed between the conductive substrate 21 and the second conductivity-type semiconductor layer 15 . The reflective layer 22 may be formed of a conductive material to electrically connect the conductive substrate 21 and the second conductivity-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 upper 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 reflective member 141 to the third reflective member 143 may be formed of DBR. If the first reflective member 141 and the third reflective member 143 are formed of metal, an insulating layer for insulating the first electrode pad 17 and the first conductive type semiconductor layer 13 is further formed. it should be Alternatively, the first electrode pad 17 may be omitted, and the first reflective member 141 to the third reflective member 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 side surfaces of the light emitting diode chip 20 by the first reflective member 141 to the third reflective member 143 . Also, 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, the light emission position of the light emitting diode chip 20 and the amount of light can be controlled, and the structure can be simplified.

An example in which the reflective member 140 is formed in a light emitting diode chip having a horizontal structure and a vertical structure has been described with reference to FIGS. 3 and 4 . However, the structure of the light emitting diode chip ( 130 in FIG. 2 ) applied to the embodiment of the present invention is not limited to FIGS. 3 and 4 . The light emitting diode chip 130 in FIG. 2 may be a light emitting diode chip having any structure capable of wire bonding and flip chip bonding. In addition, the reflective member 140 may be formed in any portion of the light emitting diode chip 130 that needs to control the amount of light.

In addition, the light emitting diode chip ( 130 of FIG. 2 ) having various structures to which the reflective member 140 is applied may be applied to other embodiments of the backlight unit thereafter.

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

Referring to FIG. 5 , the backlight unit 200 according to the second embodiment includes a light guide plate 110 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 140 , a wavelength conversion member 210 , and a sealing member. member 150 .

The description of the circuit board 120 , the light emitting diode chip 130 , the reflective member 140 , and the sealing member 150 among the constituent parts of the backlight unit 200 according to the second embodiment has already been described through the previous embodiments. did. Therefore, in the description of the following embodiments including this embodiment, the overlapping parts previously described will be omitted.

The backlight unit 200 according to the present embodiment includes the light emitting diode chip 130 and the wavelength conversion member 210 surrounding the reflective member 140 . The sealing member 150 is filled in the opening 111 of the light guide plate 110 to surround the wavelength conversion member 210 .

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

The wavelength conversion member 210 may be a mixture of a transparent resin and a phosphor that converts the wavelength of light. For example, the transparent resin may be transparent silicon (Silicone). As the phosphor, a yellow phosphor, a red phosphor, or a green phosphor may be used.

Examples of the yellow phosphor include YAG:Ce(T3Al5O12:Ce)-based phosphors or silicate-based phosphors, which are yttrium (Y) aluminum (Al) garnet, doped with cerium (Ce) having a wavelength of 530 to 570 nm. can be heard

Examples of the red (R) phosphor include a YOX (Y2O3:EU)-series phosphor or a nitride phosphor composed of a compound of yttrium oxide (Y2O3) and europium (EU) having a wavelength of 611 nm as a dominant wavelength.

Examples of the green (G) phosphor include phosphoric acid (Po4), lanthanum (La), and terbium (Tb), which is a compound of phosphoric acid (Po4) having a wavelength of 544 nm, and LAP (LaPo4:Ce,Tb)-based phosphors.

Examples of the blue (B) phosphor include a BAM (BaMgAl10O17:EU)-based phosphor, which is a compound of barium (Ba) and magnesium (Mg), aluminum oxide, and europium (EU), having a wavelength of 450 nm. can

In addition, the phosphor may include a fluoride compound KSF phosphor (K2SiF6), which is an Mn4+ activator phosphor advantageous for high color reproduction.

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

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

Referring to FIG. 6 , the backlight unit 300 according to the third embodiment includes a light guide plate 110 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 140 , and a wavelength conversion member 210 . do.

In the present embodiment, the wavelength conversion member 210 converts the wavelength of light and at the same time serves as a sealing member for protecting the light emitting diode chip 130 . The wavelength conversion member 210 contains a phosphor for converting a wavelength of light in a transparent resin serving as a sealing member.

As such, the backlight unit 300 can omit the sealing member, thereby simplifying the structure and reducing costs.

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

Referring to FIG. 7 , the backlight unit 400 according to the fourth embodiment includes a light guide plate 110 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 140 , a wavelength conversion member 210 , and a sealing member. member 150 .

The backlight unit 400 of the present embodiment includes the wavelength conversion member 210 surrounding the light emitting diode chip 130 .

In the present embodiment, the wavelength conversion member 210 is formed to surround the side and top surfaces of the light emitting diode chip 130 . In this case, the bottom layer of the reflective member 140 may be formed to cover the entire upper surface of the wavelength conversion member 210 .

The light emitted from the side of the light emitting diode chip 130 is wavelength-converted and directed toward the light guide plate 110 . In addition, the light emitted from the upper surface of the light emitting diode chip 130 is wavelength-converted and directed toward the reflective member 140 . That is, since the wavelength of the light reflected by the reflective member 140 has already been converted on the upper 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 surface 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 to make it thicker. That is, the wavelength conversion member 210 is capable of uniform optical wavelength conversion as a whole by adjusting the thickness of the upper portion and the side thickness in consideration of only the light emitted from the upper portion and the side surface of the light emitting diode chip 130 .

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

Referring to FIG. 8 , the backlight unit 500 according to the fifth embodiment includes a light guide plate 110 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 510 , and a sealing member 150 . .

According to this embodiment, the reflective member 510 may include a reflective material 511 in a light-transmitting resin. The light-transmitting resin constituting the reflective member 510 may be a known material such as a silicone resin or an epoxy resin. Alternatively, the light-transmitting resin constituting the reflective member 510 may be formed of a material having a refractive index similar to that of the light guide plate 110 in order to minimize reflection of light due to a difference in refractive index at the interface of the light guide plate 110 . For example, the light-transmitting resin of the reflective member 510 may be a silicone resin having a refractive index difference of 10% or less with the light guide plate 110 .

The sealing member 150 is filled only between the side surface of the light emitting diode chip 130 and the inner wall of the light guide plate 110 . In this case, the upper surface of the sealing member 150 is positioned on the same line as the upper surface of the light emitting diode chip 130 .

The reflective member 510 is positioned on the upper surface of the light emitting diode chip 130 and the upper surface of the sealing member 150 , and is formed to fill the opening 111 of the light guide plate 110 . Accordingly, the light emitted from the upper surface of the light emitting diode chip 130 may pass through the light-transmitting resin and be reflected by the reflective material 511 to be incident on the inner wall of the light guide plate 110 .

Although the upper surface of the sealing member 150 is formed to be positioned on the same line as the upper surface of the light emitting diode chip 130 , the structure of the present exemplary embodiment is not limited thereto. For example, the reflective member 510 may be formed to be positioned only on the upper portion of the light emitting diode chip 130 . In addition, the sealing member 150 may be formed to fill the space between the side surface of the light emitting diode chip 130 and the side surface of the reflective member 510 and the light guide plate 110 . In addition, the sealing member 150 and the reflective member 510 may further contain a phosphor for converting the wavelength of light.

The reflective member 510 according to the present embodiment may control the amount of light emitted from the upper surface of the light emitting diode chip 130 or reflected laterally by adjusting the content of the reflective material 511 . That is, in the backlight unit 500 of this embodiment, only by adjusting the content of the reflective material 511 of the reflective member 510 , the light emitted through the upper surface of the light guide plate 110 and the opening 111 of the light guide plate 110 . It is easy to control the amount of emitted light.

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

Referring to FIG. 9 , the backlight unit 600 according to the sixth embodiment includes a light guide plate 610 , a circuit board 120 , a light emitting diode chip 130 , a reflective member 510 , and a sealing member 150 . .

According to the present embodiment, the opening 611 of the light guide plate 610 has a structure in which the width becomes narrower from the lower part to the upper part. That is, as shown in FIG. 9 , the inner wall of the opening 611 of the light guide plate 610 is inclined toward the light emitting diode chip 130 from the bottom to the top. As described above, since the inner wall of the light guide plate 610 is formed to be inclined, the area of the inner wall of the light guide plate 610 increases. That is, the area of the incident surface on which the light is incident increases. Accordingly, since the incident area of the light guide plate 610 is increased, the light incident efficiency of the light guide plate 610 is improved.

According to the present embodiment, by improving the light incident efficiency of the light guide plate 610 , the light use efficiency of the backlight unit 600 may be improved.

As described above, the detailed description of the present invention has been made by the embodiments with reference to the accompanying drawings, but since the above-described embodiments have only been described with preferred examples of the present invention, the present invention is not limited to the embodiments. It should not be understood, and the scope of the present invention should be understood as the following claims and their equivalents.

11: Substrate
12: light emitting structure
13: first conductivity type semiconductor layer
14: active layer
15: 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: backlight unit
110, 610: light guide plate
111, 611: opening
120: circuit board (
10, 20, 130: light emitting diode chip
140, 510: reflective member
141: first reflective member
142: second reflective member
143: third reflective member
150: sealing member
210: wavelength conversion member
511: reflective material

Claims (18)

a light guide plate having at least one opening penetrating from the upper surface to the lower surface;
a circuit board disposed under the light guide plate;
a light emitting diode chip mounted on the circuit board, disposed in the opening of the light guide plate, and emitting light from a side surface and an upper surface;
a reflective member formed on the light emitting diode chip; and
a sealing member positioned between at least a side surface of the light emitting diode chip and an inner wall of the opening of the light guide plate;
includes,
A lower surface of the light emitting diode chip faces the circuit board,
The reflective member reflects a portion of the light emitted from the upper surface of the light emitting diode chip toward the inner wall of the opening, which is the incident surface of the light guide plate, and transmits the remaining light.
The method according to claim 1,
The reflective member is composed of a plurality of reflective members having different areas,
A backlight unit having a reflective member having a smaller area as it moves away from an upper surface of the light emitting diode chip.
The method according to claim 1,
The reflective member is a backlight unit made of a DBR (Distributed Bragg Reflector).
4. The method of claim 3,
The reflective member is a backlight unit made of at least one of SiO2, TiO2, SiN, and TiN.
3. The method according to claim 2,
The reflective member is a metal backlight unit.
6. The method of claim 5,
The reflective member is a backlight unit made of at least one of Al and Ag.
3. The method according to claim 2,
At least one reflective member of the plurality of reflective members is made of a material different from that of the other reflective members.
3. The method according to claim 2,
At least one reflective member of the plurality of reflective members has a thickness different from that of other reflective members.
The method according to claim 1,
The sealing member is a backlight unit having a refractive index difference of 10% or less from the light guide plate.
The method according to claim 1,
The sealing member further comprises a phosphor.
The method according to claim 1,
The reflective member is a light-transmitting resin containing a reflective material.
12. The method of claim 11,
The sealing member fills between the side surface of the light emitting diode chip and the inner wall of the opening of the light guide plate,
The reflective member is a backlight unit filling an upper portion of the light emitting diode chip and an upper portion of the sealing member in the opening of the light guide plate.
13. The method of claim 12,
The reflective member further comprises a phosphor.
12. The method of claim 11,
The light transmitting resin of the reflective member has a refractive index difference of 10% or less from that of the light guide plate.
The method according to claim 1,
Further comprising a wavelength conversion member formed to surround the side and upper surface of the light emitting diode chip,
The reflective member is a backlight unit positioned above the wavelength conversion member.
The method according to claim 1,
The backlight unit further comprising a wavelength conversion member formed to surround a side surface of the light emitting diode chip, a side surface of the reflection member, and an upper surface of the reflection member.
The method according to claim 1,
The incident surface of the light guide plate has an inclination such that the width of the opening becomes narrower from the lower part to the upper part.
The method according to claim 1,
The upper surface of the light guide plate is positioned on the same line as or higher than the upper surface of the reflective member.

Images