KR20110077624A - Back light unit and liquid crystal display device using that same - Google Patents

Abstract

PURPOSE: A backlight unit and a liquid crystal display device having the same are provided to improve light efficiency by improving light diffusion performance. CONSTITUTION: A backlight unit of a liquid crystal display device comprises a bottom cover(310) which has a bottom and a side wall, a light emitting diode array(320) which emits UV or color light, a light diffusing plate(330) which is placed on the bottom cover and has a color conversion layer, and a plurality of optical sheet which improves brightness property of white light. The color conversion layer is formed on the bottom surface of the light diffusing plate.

Description

Back light unit and liquid crystal display device using that same}

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

The liquid crystal display device converts the optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell to emit light by applying a voltage to a specific molecular array of the liquid crystal and converting them into other molecular arrays. Is a display device that displays information by using modulation of light by a liquid crystal cell.

Since the liquid crystal display device is not a self-light emitting device, a backlight unit is provided under the liquid crystal display panel to display an image using light emitted from the backlight unit.

The backlight unit may be classified into a side light type and a direct light type according to the arrangement of light sources.

The metering type backlight unit arranges a plurality of light sources on the side of the light guide plate provided under the liquid crystal display panel, and converts the metering light emitted from the light source through the light guide plate into flat light to irradiate the liquid crystal display panel to reduce the thickness of the backlight unit. In other words, the liquid crystal display can be made slimmer.

The direct type backlight unit is configured to arrange a plurality of light sources under the liquid crystal display panel to directly irradiate light on the front of the liquid crystal display panel, thereby increasing the uniformity and luminance of the light emitted to the liquid crystal display panel, thereby increasing the size of the liquid crystal display device. There is an advantage.

As the light source of the backlight unit, a light emitting diode (LED) having excellent advantages such as energy saving and eco-friendliness and high response speed has been in the spotlight.

1 is a view schematically showing a structure of a general direct type backlight unit.

Referring to FIG. 1, a general direct type backlight unit 100 includes a bottom cover 110, a light emitting diode array 120, a diffusion plate 130, a lower diffusion sheet 140, a lower prism sheet 150, and an upper prism. Sheet 160, and top diffusion sheet 170.

The bottom cover 110 is formed to have a bottom surface and an inclined sidewall.

The LED array 120 is disposed on the bottom surface of the bottom cover 110 to face the diffuser plate 130 to irradiate light onto the diffuser plate 130.

The diffusion plate 130 diffuses light emitted from the light emitting diode array 120 and irradiates the lower diffusion sheet 140, and the diffusion plate 130 may include a plurality of beads (diffusion beads and haze) to diffuse light. ) Beads). A process of diffusing light incident from the light emitting diode array 120 by the diffusion plate 130 will be described with reference to FIG. 2.

2 illustrates a structure of the diffuser plate 130 and an optical path in the diffuser plate 130. As shown, when light emitted from the LED array 120 is incident on the diffusion plate 130 (200), due to the difference in refractive index between the air and the diffusion plate 130, among the light incident to the diffusion plate 130 Some are transmitted 210 and some are totally reflected 220. Thereafter, the light incident into the diffuser plate 130 is transmitted by the base material constituting the diffuser plate 130 and refracted by the plurality of beads 132 included in the diffuser plate 130 (230). . The refracted light is transmitted again (240) or total reflection (250) by the refractive index of the diffusion plate 130 and air. At this time, the transmitted light is irradiated to the lower diffusion sheet 140.

The lower diffusion sheet 140 is disposed on the diffusion plate 130 to diffuse light incident from the diffusion plate 130 and to irradiate the lower prism sheet 150.

The lower prism sheet 150 is disposed on the lower diffusion sheet 140 to collect light incident from the lower diffusion sheet 140 in the first direction. Here, the first direction may correspond to the long axis or short axis direction of the diffusion plate 130.

The upper prism sheet 160 is disposed on the lower prism sheet 150 to collect light incident from the lower prism sheet 150 in the second direction. Here, the second direction may be a direction orthogonal to the first direction.

The upper diffusion sheet 170 is disposed on the upper prism sheet 160 to diffuse light incident from the upper prism sheet 160 to emit the light to the outside.

As described above, the general direct type backlight unit 100 transmits light emitted from the LED array 120 disposed on the bottom cover 110 to the diffusion plate 130, the diffusion sheets 140 and 170, and the prism sheet 150. It is diffused and collected through the 160 to emit to the outside.

However, in the case of the direct type backlight unit 100, the difference in refractive index between the base material constituting the diffuser plate 130 and the beads 132 is small so that the diffusion function of the diffuser plate 130 may be increased or the light efficiency may be increased. There is a problem that there is a limit.

In addition, in order to increase the diffusion function and the light efficiency of the diffusion plate 130, expensive beads 132 must be used in a large amount, thereby increasing the manufacturing cost of the backlight unit and the liquid crystal display device.

Disclosure of Invention The present invention has been made in view of the above-described problems, and an object thereof is to provide a backlight unit capable of improving light efficiency by improving a diffusion function and a liquid crystal display device using the same.

In addition, another object of the present invention to provide a backlight unit and a liquid crystal display device using the same that can reduce the manufacturing cost.

Another object of the present invention is to provide a backlight unit having a reduced thickness and a liquid crystal display device using the same.

According to an aspect of the present invention, there is provided a backlight unit including: a bottom cover having a bottom surface and a side wall; A light emitting diode array disposed on a bottom surface of the bottom cover to emit ultraviolet (UV) light or color light; A diffusion plate including a color conversion layer for converting the ultraviolet light or color light into white light and disposed on the bottom cover to be spaced apart from the light emitting diode array by a predetermined distance to diffuse the white light; And a plurality of optical sheets disposed on the diffuser plate to improve luminance characteristics of white light emitted from the diffuser plate, wherein the color conversion layer is formed on a bottom surface of the diffuser plate.

 According to another aspect of the present invention, a backlight unit includes: a liquid crystal display panel for displaying an image by adjusting light transmittance; And a backlight unit irradiating light to the liquid crystal display panel, wherein the backlight unit includes a bottom cover having a bottom surface and sidewalls; A light emitting diode array disposed on a bottom surface of the bottom cover to emit ultraviolet (UV) light or color light; A diffusion plate including a color conversion layer for converting the ultraviolet light or color light into white light and disposed on the bottom cover to be spaced apart from the light emitting diode array by a predetermined distance to diffuse the white light; And a plurality of optical sheets disposed on the diffuser plate to improve luminance characteristics of white light emitted from the diffuser plate, wherein the color conversion layer is formed on a bottom surface of the diffuser plate.

According to the present invention, there is an effect that the light diffusion function and the light efficiency can be improved by forming a color conversion layer including a base material constituting the diffusion plate and a material having a large difference in refractive index in the diffusion plate.

In addition, the present invention has the effect of reducing the manufacturing cost of the backlight unit and the liquid crystal display device by minimizing the use of beads for light diffusion.

In addition, the present invention can improve the light diffusion efficiency by forming protrusions or grooves having a predetermined shape in the diffusion plate, so that the number of expensive diffusion sheets can be reduced. There is an effect that can be reduced.

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

3 is a diagram schematically illustrating a structure of a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the backlight unit 300 according to the exemplary embodiment may include a bottom cover 310, a light emitting diode array 320, a diffusion plate 330 having a color conversion layer 332 formed therein, and a lower portion thereof. A prism sheet 340, an upper prism sheet 350, and a diffusion sheet 360.

The bottom cover 310 is formed to have a bottom surface and sidewalls. The bottom cover 310 accommodates the LED array 320 and supports the diffusion plate 330, the lower prism sheet 340, the upper prism sheet 350, and the diffusion sheet 360. In addition, the bottom cover 310 may be formed of a metal material to dissipate heat generated from the light emitting diode array 320.

The light emitting diode array 320 is disposed on the bottom surface of the bottom cover 310 to emit the first color light toward the diffuser plate 330. To this end, the LED array 120 includes a printed circuit board 322 and a plurality of light sources 324.

The printed circuit board 322 is disposed on the bottom surface of the bottom cover 310 to face the diffuser plate 330. In this case, the printed circuit board 322 may include a driving power line to which driving power is supplied from the outside, and may be made of a metal material (eg, aluminum) having excellent heat dissipation characteristics. The printed circuit board 322 emits light by supplying driving power supplied from the outside through the driving power line to the plurality of light sources 324.

On the other hand, the printed circuit board 322 emits heat generated by the plurality of light sources 324 to be distributed to the bottom cover 310 to dissipate heat, and heat transfer efficiency between the printed circuit board 322 and the bottom cover 310. The higher the value, the higher the heat dissipation efficiency of the light source 324 can be. To this end, the present invention further includes a thermally conductive bonding member (not shown) formed between the printed circuit board 322 and the bottom cover 310 to transfer the heat of the printed circuit board 322 to the bottom cover 110. can do. The thermally conductive bonding member may be aluminum epoxy, ceramic epoxy, or thermally conductive sheet.

The plurality of light sources 324 may be configured as a light emitting diode package including a light emitting diode chip. As shown in the enlarged area of FIG. 3, the LED package may include a lead frame 324a, a LED chip 324b, and a molding unit 324c.

The lead frame 324a is disposed on the printed circuit board 322 and electrically connected to the driving power line. The lead frame 324a includes a plurality of lead terminals and inclined grooves. A plurality of lead terminals are electrically connected to the drive power line. The inclined groove is formed to be concave to have an inclined surface from the upper surface, and the light emitting diode chip 324b and the molding portion 324c are formed therein.

The light emitting diode chip 324b is disposed on the bottom surface of the inclined groove included in the lead frame 324a and is electrically connected to the lead terminal of the lead frame 324a. The light emitting diode chip 324b is a light emitting diode chip 324b that emits color light (for example, blue light) by emitting light by a driving power supplied from a lead terminal, or the light emitting diode chip 324b that emits ultraviolet light (UV). May be).

The molding part 324c is filled in the inclined groove to protect the light emitting diode chip 324b. The molding part 324c may be flatly filled in the inclined groove in which the light emitting diode chip 324b is installed by using a filling material such as epoxy or silicon gel having excellent light transmittance.

As described above, since the color conversion layer 332 for converting color light or ultraviolet light into white light is formed in the diffusion plate 330, it is not necessary to inject a fluorescent material into the molding part 324c. .

In the above-described embodiment, the plurality of light sources 324 are described as being packaged, but in the modified embodiment, the light emitting diode chip 324b emitting color light or ultraviolet light is mounted on the printed circuit board 322. After direct mounting, the molding part may be formed in a dome shape to protect the LED chip 324b.

The diffusion plate 330 is disposed on the bottom cover 310 so as to be spaced apart from the LED array 320 by a predetermined distance to diffuse the light incident from the LED array 320. The diffusion plate 330 may be formed of a transparent plastic material having a high refractive index. Such plastic-based materials include polycarbonate (PC), polymethyl methacrylate (PMMA), and methacrylate styrene copolymer (MS).

In the diffusion plate 330 according to the present invention, a color conversion layer 332 for converting color light or ultraviolet light incident from the light emitting diode array 320 into white light is formed therein. In this case, the color conversion layer 332 may be formed using a fluorescent material.

In the present invention, the reason for forming the color conversion layer 332 by using a fluorescent material inside the diffuser plate 330 is that the difference in refractive index between the fluorescent material and the transparent plastic-based material that is the base material for forming the diffuser plate 330 is large. This is because the light diffusion function can be improved.

That is, in the conventional case, the refractive index of the base material is about 1.58 and the refractive index of the beads included in the diffusion plate for light diffusion is about 1.45, so the refractive index difference is only about 0.13. Since the refractive index is about 1.83, the difference between the refractive indices of the base material and the fluorescent material is about 0.25, so that the light diffusing function is improved as compared with the conventional art.

Therefore, the diffusion plate 330 according to the present invention may include only a small amount of beads or no beads at all.

In one embodiment, when the light emitting diode chip 324b is a blue light emitting diode chip 324b that emits blue light, the color conversion layer 332 may be a yellow fluorescent material such as YAG (Y3AL5O12): Ce or a red and red fluorescent material. It may include. In addition, when the light emitting diode chip 324b is the UV light emitting diode chip 324b that emits ultraviolet rays, the color conversion layer 332 may include red, green, and blue fluorescent materials.

In this case, the color conversion layer 332 may be formed to a predetermined thickness on the inner bottom surface of the diffusion plate 330, which is the shortest distance from which the fluorescent material may be excited. For example, the color conversion layer 332 may be formed on the inner bottom surface of the diffusion plate 330 to have a thickness of 300 μm or less.

On the other hand, the diffusion plate 330 according to the present invention may include a plurality of protrusions formed in a predetermined shape on one surface of the diffusion plate 330 to maximize the diffusion function. Hereinafter, a diffusion plate in which a plurality of protrusions are formed will be described with reference to FIGS. 4 to 7.

4A and 4B illustrate a diffusion plate 330 in which a plurality of protrusions are formed according to the first embodiment of the present invention. 4A and 4B, in the case of the diffusion plate 330 according to the first embodiment of the present invention, a plurality of protrusions 400 having a prism shape may be formed on one surface of the diffusion plate 330. . The prism-shaped protrusion 400 may be elongated in the short axis direction of the diffusion plate 330 as shown in FIG. 4A or may be elongated in the long axis direction of the diffusion plate 330 as shown in FIG. 4B.

4A and 4B, the vertex angle of the prism-shaped protrusion 400 is shown as forming a tip, but in the modified embodiment, the vertex angle of the prism-shaped protrusion 400 may be rounded.

In one embodiment, each prism-shaped protrusion 400 has a pitch W of 5 μm to 300 μm and is formed to form an inclination angle α of 31.5 ° to 50 ° with the surface of the diffusion plate 330. Can be. At this time, the inclination angle of the protrusion 400 may be the same both sides as shown in Figures 4a and 4b, otherwise may be different from each other in the range of 31.5 ° to 50 °.

The reason why the prism-shaped protrusion 400 has a pitch of 5 μm to 300 μm is that when the pitch is smaller than 5 μm, the protrusion 400 is too small to realize a diffusion function, and when the pitch is larger than 300 μm, the protrusion ( 400 is so large that it can be visually identified.

In addition, the reason why the prism-shaped protrusion 400 forms an inclination angle of 31.5 degrees to 50 degrees with the surface of the diffusion plate 330 is, as can be seen in Table 1 and FIG. 4C below, the inclination angle is greater than 31.5 degrees. If it is small or larger than 50 DEG, the luminance and the amount of light decrease and the luminance uniformity increases.

Table 1 below is a table showing luminance, luminance uniformity, and amount of light according to the inclination angle of the surface of the protrusion 400 and the diffusion plate 330 when the pitch of the protrusion 400 is 300 μm.

5A and 5B illustrate a diffusion plate 330 in which a plurality of protrusions are formed according to a second embodiment of the present invention. 5A and 5B, in the diffuser plate 330 according to the second embodiment of the present invention, a plurality of protrusions 500 having a lenticular lens shape may have one surface of the diffuser plate 330. Can be formed on. The lenticular lens-shaped protrusion 500 may be elongated in the short axis direction of the diffusion plate 330 as shown in FIG. 5A or may be formed in the long axis direction of the diffusion plate 330 as shown in FIG. 5B. have.

In one embodiment, the lenticular lens-shaped protrusion 500 may be formed such that the pitch W and the height H have a ratio of 2: 1. For example, when the pitch of the protrusion 500 is 300 μm, the protrusion 300 may be formed such that the height of the protrusion 500 is 150 μm.

6 is a view showing a diffusion plate 330 in which a plurality of protrusions are formed according to a third embodiment of the present invention. As shown in FIG. 6A, in the diffusion plate 330 according to the third embodiment of the present invention, a plurality of protrusions 600 having a quadrangular pyramid shape may be formed on one surface of the diffusion plate 330.

In FIG. 6A, the vertex angle of the quadrangular pyramid-shaped protrusion 600 is formed as a tip, but in a modified embodiment, the vertex angle of the quadrangular pyramid-shaped protrusion 600 may be rounded.

In one embodiment, each of the rectangular pyramidal protrusions 600 has a pitch W of 5 μm to 300 μm, and forms an inclination angle α of 32.5 ° to 48.5 ° with the surface of the diffusion plate 330. Can be. At this time, the inclination angle of the protrusion 600 may be the same on both sides, as shown in Figure 6a, otherwise may be different from each other in the range of 32.5 ° to 48.5 °.

The reason why the square-shaped protrusion 600 has a pitch of 5 μm to 300 μm is that if the pitch is smaller than 5 μm, the protrusion 600 is too small to implement a diffusion function, and if the pitch is larger than 300 μm, the protrusion ( 600) is too large to be visually identified.

In addition, the reason why the rectangular pyramidal protrusion 600 forms an inclination angle of 32.5 degrees to 48.5 degrees with the surface of the diffusion plate 330 is, as can be seen in Table 2 and FIG. 6B below, the inclination angle is greater than 32.5 degrees. If it is small or larger than 48.5 °, the luminance and light amount decrease and the luminance uniformity increases.

Table 2 below is a table showing luminance, luminance uniformity, and light amount according to the inclination angle of the surface of the protrusion 600 and the diffusion plate 330 when the pitch of the protrusion 600 is 300 μm.

7 is a view showing a diffusion plate 330 in which a plurality of protrusions are formed according to a fourth embodiment of the present invention. As shown in FIG. 7, in the case of the diffusion plate 330 according to the fourth embodiment of the present invention, a plurality of protrusions 700 having a hemispherical shape may be formed on one surface of the diffusion plate 330. have.

In one embodiment, each hemispherical protrusion 700 may be formed such that the pitch W and the height H have a ratio of 2: 1. For example, when the pitch of the protrusion 700 is 300 μm, the protrusion 700 may be formed such that the height of the protrusion 700 is 150 μm.

In the above-described first to fourth embodiments, the diffusion plate 330 may be formed to have a thickness of about 1500 μm including the protrusions 400 to 700.

In the above-described first to fourth embodiments, it is described that a plurality of protrusions having a predetermined shape is formed on one surface of the diffusion plate 330 to maximize the diffusion function. However, in modified embodiments, a plurality of grooves having a predetermined shape may be formed on one surface of the diffusion plate 330 to maximize the diffusion function. Hereinafter, a diffusion plate in which a plurality of grooves are formed will be described with reference to FIGS. 8 to 11.

8A and 8B illustrate a diffusion plate 330 in which a plurality of grooves are formed according to a fifth embodiment of the present invention. 8A and 8B, in the case of the diffusion plate 330 according to the fifth embodiment of the present invention, a plurality of grooves 800 having a prism shape may be formed on one surface of the diffusion plate 330. . The prism-shaped groove 800 may be elongated in the short axis direction of the diffusion plate 330 as shown in FIG. 8A, or may be formed in the long axis direction of the diffusion plate 330 as shown in FIG. 8B.

In FIGS. 8A and 8B, the vertex angle of the prism-shaped groove 800 is shown to form a tip, but in the modified embodiment, the vertex angle of the prism-shaped groove 800 may be rounded.

In one embodiment, each prism-shaped groove 800 has a pitch W of 5 μm to 300 μm, and is formed to form an inclination angle α of 31.5 ° to 50 ° with the surface of the diffusion plate 330. Can be. At this time, the inclination angle of the groove 800 may be the same as both sides shown in Figs. 8a and 8b, but may be different from each other in the range of 31.5 ° to 50 °.

The reason why the prism-shaped groove 800 has a pitch of 5 μm to 300 μm is because if the pitch is smaller than 5 μm, the groove 800 is too small to realize a diffusion function, and if the pitch is larger than 300 μm, the groove ( 800) is too large to be visually identified.

In addition, the reason why the prism-shaped groove 800 forms an inclination angle of 31.5 degrees to 50 degrees with the surface of the diffusion plate 330 is the same as that shown in Table 1 and FIG. 4C, and the inclination angle is greater than 31.5 degrees. If it is small or larger than 50 DEG, the luminance and the amount of light decrease and the luminance uniformity increases.

9A and 9B illustrate a diffusion plate 330 in which a plurality of grooves are formed according to a sixth embodiment of the present invention. 9A and 9B, in the diffusion plate 330 according to the sixth embodiment of the present invention, a plurality of grooves 900 having a lenticular lens shape may be formed on one surface of the diffusion plate 330. Can be. The lenticular lens-shaped groove 900 may be elongated in the short axis direction of the diffusion plate 330 as shown in FIG. 9A, or may be formed in the long axis direction of the diffusion plate 330 as shown in FIG. 9B. have.

In one embodiment, each lenticular lens-shaped groove 900 may be formed such that the pitch W and the depth H have a ratio of 2: 1. For example, when the pitch of the groove 900 is 300 μm, the groove 900 may be formed such that the depth of the groove 900 is 150 μm.

10 is a view illustrating a diffusion plate 330 in which a plurality of grooves are formed according to the seventh embodiment of the present invention. As shown in FIG. 10, in the diffusion plate 330 according to the seventh embodiment of the present invention, a plurality of grooves 1000 having a quadrangular pyramid shape may be formed on one surface of the diffusion plate 330.

In FIG. 10, the vertex angle of the quadrangular pyramid-shaped groove 1000 is illustrated as forming a tip, but in the modified embodiment, the vertex angle of the quadrangular pyramid-shaped groove 1000 may be rounded.

In one embodiment, each square pyramid groove 1000 has a pitch W of 5 μm to 300 μm, and is formed to form an inclination angle α of 32.5 ° to 48.5 ° with the surface of the diffusion plate 330. Can be. In this case, the inclination angle of the groove 1000 may be the same as both sides as shown in FIG. 10, but may be different from each other within the range of 32.5 ° to 48.5 °.

The reason why the square-shaped groove 1000 has a pitch of 5 µm to 300 µm is that if the pitch is smaller than 5 µm, the groove 1000 is too small to realize a diffusion function, and if the pitch is larger than 300 µm, the groove ( 1000) is so large that it can be visually identified.

In addition, the reason why the square pyramid groove 600 forms an inclination angle of 32.5 ° to 48.5 ° with the surface of the diffusion plate 330 is the same as that shown in Table 2 and FIG. 6B, and the inclination angle is greater than 32.5 °. If it is small or larger than 48.5 °, the luminance and light amount decrease and the luminance uniformity increases.

11 is a view showing a diffusion plate 330 in which a plurality of protrusions are formed according to an eighth embodiment of the present invention. As shown in FIG. 11, in the diffusion plate 330 according to the eighth embodiment of the present invention, a plurality of grooves 1100 having a hemispherical shape may be formed on one surface of the diffusion plate 330.

In one embodiment, each hemispherical groove 1100 may be formed such that the pitch W and the depth H have a ratio of 2: 1. For example, when the pitch of the groove 1100 is 300 μm, the groove 1100 may be formed such that the depth of the protrusion 1100 is 150 μm.

As described above, in the present invention, the diffusion function of the diffusion plate 330 may be maximized by forming a pattern or a groove having a predetermined shape on one surface of the diffusion plate 330.

In addition, although not shown in the drawings, in order to maximize the diffusion function of the diffusion plate 330, the projection pattern may be formed on the opposite side where the pattern or groove is formed in the diffusion plate 330.

Referring to FIG. 3 again, the lower prism sheet 340 is disposed on the diffusion plate 330 to collect white light incident from the diffusion plate 330 in the first direction to irradiate the upper prism sheet 340. Here, the first direction may correspond to the long axis or short axis direction of the diffusion plate 330.

In the case of the present invention, unlike the conventional direct backlight unit, a separate diffusion sheet is not disposed between the diffusion plate 330 and the lower prism sheet 340, which is formed on one surface of the diffusion plate 330 as described above. This is because the protruding portion or groove may serve as a diffusion sheet disposed between the diffusion plate 330 and the lower prism sheet 340.

As such, the present invention can reduce the thickness and manufacturing cost of the backlight unit 300 because no separate diffusion sheet is disposed between the diffusion plate 330 and the lower prism sheet 340.

The upper prism sheet 350 is disposed on the lower prism sheet 340 to collect white light incident from the lower prism sheet 340 in the second direction to irradiate the diffusion sheet 360. Here, the second direction may be a direction orthogonal to the first direction. The upper prism sheet 350 may be omitted according to the structure of the backlight unit 300.

The diffusion sheet 360 is disposed on the upper prism sheet 350 and diffuses white light incident from the upper prism sheet 350 to emit to the outside (eg, a liquid crystal display panel). In this case, when the upper prism sheet 350 is omitted, the diffusion sheet 360 may be disposed on the lower prism sheet 340 to diffuse white light incident from the lower prism sheet 340 to emit to the outside.

12 illustrates a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 12, in the liquid crystal display according to the exemplary embodiment, the liquid crystal display panel 370 for displaying an image by adjusting the light transmittance and the backlight unit 300 for irradiating light to the liquid crystal display panel 370. ).

The liquid crystal display panel 370 adjusts the light transmittance of the liquid crystal layer (not shown) formed between the first substrate (not shown) and the second substrate (not shown) by using light emitted from the backlight unit 300. Display the video.

The backlight unit 300 includes a bottom cover 310, a light emitting diode array 320, a diffusion plate 330 on which a color conversion layer 332 is formed, a lower prism sheet 340, and an upper prism sheet as illustrated in FIG. 3. 350, and diffusion sheet 360. In this case, the diffusion plate 330 may have a plurality of protrusions or grooves having a predetermined shape as shown in FIGS. 4 to 11. Since each component 310 to 360 included in the backlight unit 300 is the same as that shown in FIG. 3, a detailed description thereof will be omitted.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention may include a color conversion layer 332 and the backlight unit 300 including a diffusion plate 330 having a plurality of protrusions or grooves having a predetermined shape. The brightness and image quality of the image may be improved by displaying an image by adjusting the light transmittance of uniformly incident white light without color deviation due to color dispersion.

On the other hand, those skilled in the art will understand that the present invention described above 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 schematically showing the structure of a general direct type backlight unit.

FIG. 2 is a view showing the structure of the diffuser plate shown in FIG. 1 and an optical path in the diffuser plate. FIG.

3 is a view schematically showing the structure of a direct type backlight unit according to an embodiment of the present invention.

4 to 11 show a diffusion plate according to the first to eighth embodiments of the present invention.

12 illustrates a structure of a liquid crystal display according to an exemplary embodiment of the present invention.

Claims (10)

A bottom cover having a bottom surface and sidewalls; A light emitting diode array disposed on a bottom surface of the bottom cover to emit ultraviolet (UV) light or color light; A diffusion plate including a color conversion layer for converting the ultraviolet light or color light into white light and disposed on the bottom cover to be spaced apart from the light emitting diode array by a predetermined distance to diffuse the white light; And A plurality of optical sheets disposed on the diffuser plate to improve luminance characteristics of white light emitted from the diffuser plate, And the color conversion layer is formed on a bottom surface of the diffusion plate. The method of claim 1, The color conversion layer includes a fluorescent material for converting the ultraviolet light or color light into the white light, The color conversion layer has a thickness of less than 300㎛. The method of claim 1, wherein the plurality of optical sheets, At least one prism sheet disposed on the diffusion plate to collect white light emitted from the diffusion plate; And And a diffusion sheet disposed on the prism sheet to diffuse white light incident from the prism sheet. The method of claim 1, The diffusion plate includes at least one prism shape or a prism shape groove formed on one surface of the diffusion plate, and the prism shape protrusion and the prism shape groove have a pitch of 5 μm to 300 μm. And a tilt angle of 31.5 ° to 50 ° with respect to the surface of the diffusion plate. 5. The method of claim 4, The prism-shaped protrusions and the prism-shaped grooves are elongated in the long axis direction or the short axis direction of the diffusion plate. The method of claim 1, The diffusion plate includes one or more protrusions having a lenticular lens shape or one or more grooves having a lenticular lens shape formed on one surface of the diffusion plate, and the protrusions having a lenticular lens shape have a pitch and height. And a 2: 1 ratio, and the grooves having the lenticular lens shape have a ratio of 2: 1 in pitch and depth. The method of claim 6, The projection unit having the lenticular lens shape and the groove having the lenticular lens shape are elongated in the long axis direction or the short axis direction of the diffusion plate. The method of claim 1, The diffusion plate includes one or more protrusions or triangular pyramid-shaped protrusions formed on one surface of the diffusion plate, and the triangular pyramidal protrusions and triangular pyramidal grooves have a pitch of 5 μm to 300 μm. And having an inclination angle of 32.5 ° to 48.5 ° with respect to the surface of the diffusion plate. The method of claim 1, The diffuser plate includes at least one hemispherical protrusion or at least one groove having a hemispherical shape formed on one surface of the diffuser plate, wherein the hemispherical protrusion has a ratio of pitch and height of 2: 1 and the hemisphere The groove in the shape of the backlight unit, characterized in that the ratio of the pitch and depth 2: 1. A liquid crystal display panel for adjusting an optical transmittance to display an image; And A liquid crystal display device comprising the backlight unit according to any one of claims 1 to 9 for irradiating light to the liquid crystal display panel.

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