KR20110057802A - Back light unit, method for manufacturing thereof, and liquid crystal display using that back light unit - Google Patents

Abstract

PURPOSE: A backlight unit, manufacturing method thereof, and liquid crystal display using the same are provided to reduce the optical loss due to the separation of an optical axis between a light source unit and a light guide plate. CONSTITUTION: A light guiding plate(320) guides light which is income from a first light source unit(330). A first reflection plate(310) is arranged in the lower side of a light guide plate. An optical sheet(340) is arranged in the upper side of the light guide plate. The light guiding plate is formed in a first light source unit in order to increase the luminance of the light.

Description

Back Light Unit, Method for Manufacturing Thereof, and Liquid Crystal Display Using That Back Light Unit}

The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit of a liquid crystal display device.

Liquid crystal displays (LCDs) are light-receiving elements that do not emit light by themselves, and thus require a separate light source. Accordingly, the liquid crystal display device arranges a backlight unit serving as a light source under the liquid crystal panel, and enters the light emitted from the backlight unit into the liquid crystal panel to adjust the amount of light transmitted according to the arrangement of the liquid crystals to display an image. do.

In this case, a light emitting diode (LED) or a cold cathode fluorescent lamp (CCFL) may be used as a light source. Recently, the use of a backlight unit using a light emitting diode as a light source is increasing. .

1 is a cross-sectional view of a backlight unit used in a general liquid crystal display device. As illustrated, the backlight unit 100 may include a reflector 110, a light guide plate 120 disposed on an upper surface of the reflector plate 110, an optical sheet 130 disposed on an upper surface of the light guide plate 120, and one side of the light guide plate 120. A light source unit 140 disposed to be spaced apart by a predetermined distance to the light source unit 140, a guide panel 150 having a curved shape to cover one side of the optical sheet 130, and a lowermost part of the backlight unit 100. The cover bottom 160 is disposed on the reflective plate 110 and bonded to the guide panel 150.

As shown in FIG. 1, the reason why the light source unit 140 is configured to be spaced apart from the light guide plate 120 by the backlight unit 100 may be due to the influence of heat generated from the light source unit 140 on the optical sheet 130. In order to minimize and to solve a hot spot problem in which point defects occur in a liquid crystal panel (not shown).

However, in the conventional backlight unit 100, due to the distance between the light source unit 140 and the light guide plate 120, the light generated by the light source unit 140 does not directly enter the light guide plate 120, but passes through the air medium. Since the structure is incident on the light emitting diode 120, light reflected by the large refractive index difference at the boundary between the air and the light guide plate 120 is generated as shown in FIG. 2A, resulting in a large amount of light loss. There is a problem.

Specifically, as illustrated in FIG. 2B, when the distance between the light source unit 140 and the light guide plate 120 is 0.5 mm, the light efficiency is 91%, and when the interval is 1.0 mm, the light efficiency is 84%, and the interval is 1.5 mm. When the light efficiency is 73%, it can be seen that the light efficiency decreases as the interval increases.

In addition, in the conventional backlight unit 100, since the light source unit 140 and the light guide plate 120 are spaced apart from each other, the optical axis of the light source unit 140 and the light guide plate 120 is off ( There is also a problem that optical loss may occur due to Decenter.

Specifically, as shown in FIG. 2C, when the distance between the light source unit 140 and the light guide plate 120 is 1.0 mm and the degree of deviation of the optical axis is 0 mm, the light efficiency is 84%, and the degree of deviation of the optical axis is 0.5 under the same conditions. In the case of mm, the light efficiency is 80%, and when the degree of deviation of the optical axis is 1.0mm, the degree of light efficiency is 73%. As the degree of deviation of the optical axis increases, the light efficiency decreases.

In addition, the liquid crystal display may use an edge type LED backlight unit 100 for slimming, and the edge type LED backlight unit 100 may not implement local dimming. There is this.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a backlight unit including a light guide plate having a light source unit, a manufacturing method thereof, and a liquid crystal display device using the same.

In addition, another object of the present invention is to provide a backlight unit having an inclined top and bottom edge portions of a light guide plate in which a light source unit is built, a manufacturing method thereof, and a liquid crystal display device using the same.

Another object of the present invention is to provide a backlight unit having a reflecting plate disposed on an upper surface of a light guide plate in which a light source unit is built, a manufacturing method thereof, and a liquid crystal display device using the same.

In addition, another object of the present invention is to provide a backlight unit capable of adjusting the radiation angle of a light emitting diode constituting the light source unit, a method of manufacturing the same, and a liquid crystal display device using the same.

Another object of the present invention is to provide a backlight unit including a light guide plate in which a plurality of light sources are embedded, a manufacturing method thereof, and a liquid crystal display device using the same.

A backlight unit according to an aspect of the present invention for achieving the above object, the light guide plate for advancing the light incident from the first light source unit built in at least one side to the upper surface; A first reflector disposed on a lower surface of the light guide plate to reflect light incident through the lower surface of the light guide plate to the light guide plate; And an optical sheet disposed on an upper surface of the light guide plate to improve brightness characteristics of light propagated from the light guide plate.

According to another aspect of the present invention, a liquid crystal display device includes: a liquid crystal panel configured to display an image by adjusting light transmittance; And a backlight unit for irradiating light to the liquid crystal panel, wherein the backlight unit comprises: a light guide plate configured to advance light incident from a first light source unit built in at least one side to an upper surface; A first reflector disposed on a lower surface of the light guide plate to reflect light incident through the lower surface of the light guide plate to the light guide plate; And an optical sheet disposed on an upper surface of the light guide plate to improve brightness characteristics of light propagated from the light guide plate.

According to an aspect of the present invention, there is provided a method of manufacturing a backlight unit, including: providing a light guide plate having a light source unit built in at least one side; Disposing a first reflector on a bottom surface of the light guide plate; And arranging an optical sheet on an upper surface of the light guide plate, and the preparing of the light guide plate may include: mounting the light source unit on at least one side of a frame; Injecting a curable material into the frame; And curing the curable material by irradiating the curable material with ultraviolet rays.

According to the present invention, by incorporating the light source into the light guide plate, it is possible to reduce the light loss due to deviation of the optical axis between the light source and the light guide plate due to light reflection and mechanism tolerance due to the distance between the light source and the light guide plate, thereby improving the light efficiency. It works.

 In addition, the present invention has a top and bottom edge portion of the light guide plate in which the light source unit is built, the inclined surface, or a reflecting plate on the top surface of the light guide plate in which the light source is built, or the emission angle of the light emitting diode constituting the light source portion There is an effect that the light efficiency can be further improved by adjusting.

In addition, the present invention has an effect that local dimming can be implemented in the edge-type backlight unit by embedding a plurality of light sources in the light guide plate.

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

First embodiment

3A is a cross-sectional view of the backlight unit according to the first embodiment of the present invention, and FIG. 3B is a perspective view showing a part of the backlight unit according to the first embodiment.

3A and 3B, the backlight unit 300 according to the first embodiment of the present invention may include a light guide plate 320 in which a first reflecting plate 310 and a first light source unit 330 are embedded, and an optical unit. The seat 340, the guide panel 350, and the cover bottom 360 are included.

The first reflecting plate 310 is to prevent light loss by reflecting light incident through the lower surface of the light guide plate 320 to the light guide plate 320 and disposed on the bottom surface of the cover bottom 360. In this case, the first reflection plate 310 may be formed to be the same as or larger than the width of the light guide plate 310 to prevent light leakage of the light reflected from the light guide plate 320.

In one embodiment, the first reflector 310 may be generally in the form of a thin film or sheet, and coated with silver on a base material such as SUS, brass, aluminum, PET, or the like to increase the reflectance. 1 In order to prevent deformation due to heat generated from the light source unit 330 may be coated with titanium.

The light guide plate 320 propagates the light incident from the first light source unit 330 embedded in at least one side of the light guide plate 320 to the optical sheet 330 and is disposed on an upper surface of the first reflecting plate 310. 3A and 3B, the first light source unit 330 is shown to be embedded only on one side of the light guide plate 320, but in a modified embodiment, the first light source unit 330 corresponds to four sides of the light guide plate 320. It may be embedded in at least one of the regions.

As such, incorporating the first light source 330 into the light guide plate 320 in the present invention reduces the distance between the light guide plate 320 and the first light source 330 and between the light guide plate 320 and the first light source 330. This is to reduce the loss of light incident from the first light source unit 330 by eliminating the optical axis deviation caused by the device tolerance.

The light guide plate 320 may have at least one or more patterns (not shown) to allow the incident light to be refracted several times. In this case, the light guide plate 320 may be formed of polymethylmetharcylate (PMMA), plastic, resin, or glass resistant to heat.

The first light source unit 330 generates light and enters the light guide plate 320. As described above, the first light source unit 330 is provided in at least one side of the light guide plate 320. . In one embodiment, the first light source unit 330 may include one or more light emitting diodes. In this case, the one or more light emitting diodes may be spaced apart from each other on the PCB 332 in a package form. Is mounted.

At this time, the LED package is filled in the LED chip 333 that receives electrical energy and emits light having a short wavelength, the lead frame 334 in which the LED chip 333 is accommodated, and the lead frame 334 to download the short wavelength light. It is composed of a phosphor resin 335 that converts to emit white light.

 As described above, in the backlight unit according to the present invention, since the first light source unit 330 is embedded in the light guide plate 320, the light emitted by the LED chip 333 constituting the first light source unit 330 is Unlike the conventional backlight unit that proceeds to the light guide plate through air, the light guide plate 320 proceeds directly to the light guide plate 320 through silicon coated on the light emitting diode chip 334. In this case, since the difference in refractive index between the silicon and the light guide plate 320 is smaller than the difference in refractive index between the air and the light guide plate 320, the total reflection angle is increased at the light incident interface, thereby improving the light efficiency.

The optical sheet 340 improves the brightness and uniformity of light incident from the light guide plate 320 and irradiates the liquid crystal panel 370. In detail, the optical sheet 340 distributes the light incident from the light guide plate 320 and evenly supplies the entire surface of the image display unit of the liquid crystal panel 370 so that the image displayed on the liquid crystal panel 370 has an even distribution of luminance. At least one diffusion sheet 342 and the light incident from the diffusion sheet 342 to advance in a predetermined direction at a pitch and angle of the prism shape to increase the brightness of the image displayed on the liquid crystal panel 370 At least one prism sheet 344, and a protective sheet 346 for protecting the prism sheet 344.

Here, the laminated structure of each of the at least one diffusion sheet 342 and the prism sheet 344 may be sequential, non-sequential or alternating to improve brightness and uniformity of the light.

The guide panel 350 fixes the PCB 332 in which the first light source 330 mounted in the light guide plate 320 is mounted, and has a curved shape to cover one side of the optical sheet 340. 360 is positioned at the bottom of the backlight unit 300 to surround the first reflecting plate 310 and to be bonded to the guide panel 350. The thermal conductivity is 360 so that heat generated from the backlight unit 300 can be discharged to the outside. It may be formed of a high material.

The backlight unit 300 as described above is disposed on the bottom surface of the liquid crystal panel 370 that displays an image by adjusting the light transmittance, as shown in FIG. 3A, and irradiates light onto the liquid crystal panel 370 to illuminate the liquid crystal panel. The image may be displayed through the display 370.

As described above, in the first exemplary embodiment of the present invention, the first light source unit 330 is embedded in the light guide plate 320 so that the gap between the first light source unit 330 and the light guide plate 320 is eliminated and the first light source unit 330 is removed. Even if the optical axis between the light guide plate 320 and the light guide plate 320, it can be seen that the light efficiency is improved by 12% compared to the conventional backlight unit, as shown in Figure 3c.

Second embodiment

In the above-described first embodiment, only the first light source unit 330 is included in one side of the light guide plate 320 in order to improve the light efficiency. However, in the second embodiment, FIG. As illustrated in FIG. 2, inclined surfaces 410 and 420 may be formed at upper and lower edge portions of the light guide plate 320 in which the first light source unit 330 is built. As described above, in the second exemplary embodiment of the present invention, the light guide plate is formed in the first light source part 330 by forming the inclined surfaces 410 and 420 at the upper and lower edges of the light guide plate 320 in which the first light source part 330 is built. A large amount of light can be incident above the total reflection angle among the light traveling to the inside, thereby increasing the light efficiency.

In this case, the length l of the inclined surfaces 410 and 20 may be formed to prevent the light emitted from the first light source 330 from escaping to the outside through the upper surface of the light guide plate 320.

5 is a graph illustrating a result of comparing the light efficiency of the backlight unit according to the first embodiment and the light efficiency of the backlight unit according to the second embodiment. As shown in FIG. 5, an inclined surface is formed at an upper and lower corners of the light guide plate 320 in which the first light source unit 330 is built in the light guide plate 320, rather than the light efficiency of the backlight unit according to the first embodiment. It can be seen that the light efficiency of the backlight unit formed by road is better.

In addition, it can be seen that the light efficiency of the backlight unit having the inclination angle of 60 degrees is better than the light efficiency of the backlight unit having the angle of inclination surface of 45 degrees, and the light of the backlight unit having the angle of inclination surface of 60 degrees is better. It can be seen that the light efficiency of the backlight unit having the angle of inclination of 80 degrees is better than the efficiency.

That is, the graph shown in FIG. 5 shows that the light efficiency of the backlight unit is improved as the angle of the inclined surface formed on the upper and lower corners of the light guide plate 320 on the side where the first light source unit 330 is built is increased. have.

Third embodiment

In the above-described second embodiment, in order to further improve the light efficiency, the light guide plate 320 has been described as having an inclined surface formed on the upper and lower corners of the side where the first light source unit 330 is built, but for improving the light efficiency. In another embodiment, as illustrated in FIG. 6, the second reflecting plate 600 may be further disposed on the upper surface of the light guide plate 320 in which the first light source unit 330 is embedded.

As described above, in the second exemplary embodiment, the second reflecting plate 600 is additionally disposed on the upper surface of the light guide plate 320 on the side where the first light source unit 330 is built, thereby providing the light guide plate 320 in the first light source unit 330. Since a large amount of light may be incident at a total reflection angle or more, the light efficiency may be further improved.

In this case, the width W of the second reflecting plate 600 may be formed to prevent the light emitted from the first light source 330 from escaping to the outside through the upper surface of the light guide plate 320.

Fourth embodiment

In the above-described third embodiment, in order to further improve the light efficiency, the second reflecting plate 600 is further disposed on the upper surface of the light guide plate 320 in which the first light source unit 330 is embedded. In the fourth exemplary embodiment, as illustrated in FIG. 7, a plurality of protrusions 700 may be formed on the light guide plate 320 at upper and lower sides of the light source plate 330. Through this, as in the above-described second and third embodiments, a large amount of light may be incident from the first light source 330 into the light guide plate 320 at a total reflection angle or more, thereby improving light efficiency. have.

In this case, the width W of the region where the plurality of protrusions 700 are formed may be formed to prevent the light emitted from the first light source 330 from escaping to the outside through the upper surface of the light guide plate 320.

Fifth Embodiment

In the above-described embodiments, in order to further improve the light efficiency, the shape of the light guide plate 320 in which the first light source unit 330 is built may be modified, or the first light source unit 330 may be built in the light guide plate 320. Although the second reflective plate 600 is disposed on the upper surface of the side, or the plurality of protrusions 700 are formed on the upper and lower sides of the light guide plate 320 in which the first light source unit 330 is incorporated, the fifth embodiment In the present invention, light efficiency may be improved by adjusting the radiation angle of the first light source 330.

Specifically, as shown in FIG. 8, included in the lead frame 334 such that the emission angle of the light emitted from the light emitting diode chip 333 of the first light source 330 is greater than or equal to a critical angle (about 42 degrees). The light emitted from the first light source 330 may maintain the total reflection angle in the light guide plate 320 by adjusting the angle of the reflected cup.

9 is a graph illustrating a comparison of the light efficiency of the backlight unit according to the first embodiment with the light efficiency according to the fifth embodiment. As shown, it can be seen that the light efficiency of the backlight unit adjusted so that the emission angle of the first light source unit 330 is 90 degrees is better than the light efficiency of the backlight unit according to the first embodiment, and the first light source unit ( It can be seen that the light efficiency of the backlight unit in which the radiation angle of the first light source unit 330 is adjusted to 60 degrees is better than the light efficiency of the backlight unit in which the radiation angle of 330 is adjusted to 90 degrees.

Sixth embodiment

Meanwhile, in the above-described embodiments, only the first light source unit 330 is included in the light guide plate 320, but in the sixth embodiment, as illustrated in FIGS. 10A and 10B, the plurality of second light source units 380 may be used. May be further embedded in the light guide plate 320. Accordingly, a plurality of light source parts 380a to 380c are built in the light guide plate 320. In the sixth embodiment, the plurality of light sources 330, 380a ˜ 380c are embedded in the light guide plate 320 to implement local dimming in the edge type backlight unit.

Here, local dimming means a technique for more vividly displaying an image displayed on a liquid crystal display such as a large TV. More specifically, local dimming is a technique of dividing the liquid crystal panel into a plurality of regions and individually adjusting the backlight luminance value in each division region according to the gray level value of each division region. That is, the light emitting diodes of the backlight unit area corresponding to the part displayed brightly on the screen may be partially turned on, and the light emitting diodes corresponding to the remaining screen parts may be turned on at low luminance or completely turned off.

As described above, in the backlight unit according to the sixth exemplary embodiment of the present invention, the plurality of light source parts 330 and 380a to 380c are incorporated in the light guide plate 320 to individually store luminance values of the light source parts 330 and 380a to 380c. Will be able to adjust.

In one embodiment, the plurality of light source units 330, 380a ˜ 380c may be spaced apart by a predetermined interval in the light guide plate 320 in the lateral direction. In this case, each of the plurality of light sources 330, 380a ˜ 380c may be composed of one or more light emitting diodes, and the light emitting diodes may be side emitting light emitting diodes emitting side light emitted to the side. .

Hereinafter, a method of manufacturing a backlight unit according to the present invention will be described with reference to FIGS. 11 to 16.

First, as shown in FIG. 11A, a frame 1100 for forming the light guide plate 320 in which the first light source unit 330 is built is provided on at least one side thereof. In this case, the frame 1100 may include four sidewall frames 1120 and a bottom frame 1130 extending from lower ends of inner surfaces of the four sidewall frames 1120, and at least one of the four sidewall frames 1120. A groove 1122 may be formed in the side wall frame of the first light source unit 330. In this case, the number of the grooves 1122 is determined by the number of light emitting diodes constituting the first light source 330.

In the above-described embodiment, the grooves are formed in the sidewall frames 1120 to seat the first light source 330. In another embodiment, as shown in FIG. 11B, the frame 1100 may be formed. The side in which the first light source 330 is to be seated is formed in an open form, or in another embodiment, the side wall frame 1120 of the side on which the first light source 330 is to be seated is formed of a PCB on which the first light source is to be mounted. You could do it.

Next, as shown in FIG. 12, the first light source 330 is seated in the frame 1100. In detail, in the case of the frame 1100 of FIG. 11A, the first light source 330 is inserted into the groove 1122 formed in the side wall frame 1120, thereby inserting the first light source 330 into the frame 1100. In the case of the frame 1100 having the shape shown in FIG. 11B, the first light source 330 may be seated in the frame 1100 by disposing the first light source 330 on the open side.

Although not shown in the drawings, a plurality of second light source units 380a to 380c are added to the first light source unit 330 to implement local dimming using the edge type backlight unit as in the sixth embodiment. It may be seated in the furnace frame 1100. At this time, it is preferable that the first light source unit 330 and the second light source units 380a to 380c are spaced apart by a predetermined interval in the horizontal direction.

Next, as shown in FIG. 13, the curable material 1300 is injected into the frame 1100 on which the first light source 330 is seated. In one embodiment, the curable material may be a photocurable resin or a thermosetting resin.

Next, as shown in FIG. 14, the curable material injected into the frame 1100 is cured by irradiating light such as UV (Ultra Violet) onto the frame 1100 into which the curable material is injected.

In this case, the method may further include planarizing the surface of the curable material 1300 by closely contacting the frame 1100 using a separate frame (not shown).

Next, as shown in FIG. 15, the light guide plate 320 having the first light source unit 330 is formed by finally separating the curable material from the frame 1100.

On the other hand, as in the above-described second embodiment, in order to form the inclined surface on the upper and lower edges of the side of the light guide plate 320, the first light source unit 330 is built, the light guide plate having the first light source unit 330 ( After forming 320, as shown in FIG. 16A, an inclined surface is formed by cutting upper and lower edge portions of the light guide plate 320 in which the first light source 330 is built, or in FIG. 16B in the process of forming the light guide plate. By using the frame 1100 having the shape shown in FIG. 1, the inclined surface may be formed at upper and lower edge portions of the light guide plate 320 in which the first light source 330 is embedded.

In addition, in order to form the plurality of protrusions 700 on the upper and lower sides of the light guide plate 320 in which the first light source unit 330 is built, as in the above-described fourth embodiment, the bottom frame 1130 and the separate A plurality of protrusions 700 are formed on the upper and lower surfaces of the light guide plate 320 in which the first light source unit 330 is built, by forming a plurality of protrusion patterns in a region where the first light source unit 330 is to be seated in the frame. You may be able to.

Subsequently, although not shown, the first reflecting plate 310 is disposed on the lower surface of the light guide plate 320 in which the first light source unit 330 is embedded, and the optical film is disposed on the upper surface of the light guide plate 320 in which the first light source unit 330 is embedded. 340 is disposed, and the backlight unit 300 is formed.

On the other hand, before the optical film 340 is disposed on the upper surface of the light guide plate 320, the second light source is disposed on the upper surface of the light guide plate 320 in which the first light source unit 330 is embedded, as in the above-described third embodiment. The reflector 600 may be further disposed.

Those skilled in the art to which the present invention pertains will understand that the above-described present invention can be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

1 is a view illustrating a structure of a general backlight unit

FIG. 2A shows light loss due to refractive index difference at the light incident interface. FIG.

2B is a view illustrating light efficiency according to a distance between a light source unit and a light guide plate.

Figure 2c is a view showing the light efficiency according to the degree of optical axis deviation of the light source unit and the light guide plate.

3A and 3B illustrate a structure of a backlight unit according to a first embodiment of the present invention.

3C is a view showing a comparison of light efficiency of the backlight unit shown in FIG. 1 and the backlight unit according to the first embodiment shown in FIGS. 3A and 3B.

4 is a view illustrating a structure of a backlight unit according to a second embodiment of the present invention.

FIG. 5 is a graph showing light efficiency of the backlight unit according to the first embodiment and the backlight unit according to the second embodiment; FIG.

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

7 illustrates a structure of a backlight unit according to a fourth embodiment of the present invention.

8 is a view showing adjustment of the radiation angle of the light source unit according to the fifth embodiment of the present invention.

9 is a graph illustrating a comparison of light efficiency of the backlight unit according to the first embodiment and the backlight unit according to the fifth embodiment.

10A and 10B illustrate a structure of a backlight unit according to a sixth embodiment of the present invention.

11 to 16 illustrate a method of manufacturing a backlight unit according to an embodiment of the present invention.

Claims (10)

A light guide plate configured to advance light incident from the first light source unit embedded in at least one side to an upper surface; A first reflector disposed on a lower surface of the light guide plate to reflect light incident through the lower surface of the light guide plate to the light guide plate; And And an optical sheet disposed on an upper surface of the light guide plate to improve brightness characteristics of light propagated from the light guide plate. The method of claim 1, And wherein the light guide plate has an inclined surface formed at the upper and lower edge portions of the side where the first light source unit is built, to allow light incident from the first light source unit to be incident at an angle equal to or greater than a total reflection angle. The method of claim 1, And a second reflecting plate disposed between the upper surface of the light guide plate on which the first light source unit is embedded and the optical sheet. The method of claim 1, The first light source unit is a backlight unit, characterized in that composed of one or more light emitting diodes (Light Emitting Diode) having a radiation angle of more than a critical angle (Critical Angle). The method of claim 1, At least one second light source unit spaced apart from the first light source unit by a predetermined interval in the light guide plate in a lateral direction, The first and second light source unit is a backlight unit, characterized in that composed of one or more side emitting light emitting diodes. A liquid crystal panel which displays an image by adjusting light transmittance; And A liquid crystal display device comprising the backlight unit according to any one of claims 1 to 5 for irradiating light to the liquid crystal panel. Providing a light guide plate in which a light source unit is built in at least one side; Disposing a first reflector on a bottom surface of the light guide plate; And Disposing an optical sheet on an upper surface of the light guide plate; Preparing the light guide plate, Mounting the light source unit on at least one side of a frame; Injecting a curable material into the frame; And And curing the curable material by irradiating the curable material with ultraviolet rays. The method of claim 7, wherein the step of providing the light guide plate, And forming an inclined surface on upper and lower edge portions of the light guide plate in which the light source unit is built. According to claim 7, In the step of mounting the light source unit, And mounting a plurality of light source units in the frame, wherein the plurality of light source units are spaced apart by a predetermined interval in the transverse direction in the frame. 8. The method of claim 7, between disposing the first reflecting plate and disposing the optical sheet, And arranging a second reflecting plate between an upper surface of one side of the light guide plate in which the light source unit is embedded and the optical sheet.

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