KR100625440B1 - Diffusion sheet, protection sheet and backlight unit including the same - Google Patents

Abstract

The present invention relates to a backlight unit including beads having other beads. The backlight unit used in the liquid crystal display device including the liquid crystal display panel includes a light source unit, a diffusion sheet, and a prism sheet. The light source unit generates light of a predetermined wavelength. The diffusion sheet is positioned above the light source unit, includes first beads, and passes light generated from the light source unit. The prism sheet is positioned above the diffusion sheet and condenses the light passing through the diffusion sheet in the direction of the liquid crystal display panel. Here, each of the first beads includes at least one second bead therein. Since the backlight unit includes beads having different beads therein, the backlight unit may condense light traveling from the light guide plate at a predetermined angle or more.

Backlight Unit, Bead, LCD

Description

Diffusion sheet, protective sheet and backlight unit including same {DIFFUSION SHEET, PROTECTION SHEET AND BACKLIGHT UNIT INCLUDING THE SAME}

1A is a block diagram illustrating a general liquid crystal display.

FIG. 1B is a cross-sectional view illustrating the backlight unit of FIG. 1A.

2A is a cross-sectional view illustrating the diffusion sheet of FIG. 1A.

2B is a cross-sectional view of the protective sheet of FIG. 1A.

3 is a cross-sectional view illustrating a liquid crystal display using a backlight unit according to an exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating a backlight unit according to an exemplary embodiment of the present invention.

5A is a cross-sectional view illustrating the diffusion sheet of FIG. 4 in accordance with a preferred embodiment of the present invention.

5B is a cross-sectional view illustrating the prism sheet of FIG. 4 according to an exemplary embodiment of the present invention.

5C is a cross-sectional view of the protective sheet of FIG. 4 in accordance with a preferred embodiment of the present invention.

The present invention relates to a diffusion sheet, a protective sheet and a backlight unit including the same, and more particularly, to a diffusion sheet, a protective sheet and a backlight unit including the first bead having a second bead.

The backlight unit is a device that provides flat light to an LCD panel in a liquid crystal display (LCD).

FIG. 1A is a block diagram illustrating a general liquid crystal display, and FIG. 1B is a cross-sectional view of the backlight unit of FIG. 1A.

Referring to FIG. 1A, the LCD includes an LCD panel 100 and a backlight unit 102.

The backlight unit 102 provides flat light to the LCD panel 100.

The LCD panel 100 displays a predetermined image by using the plane light provided from the backlight unit 102.

Referring to FIG. 1B, the backlight unit 102 includes a light source unit 110, a light guide plate 116, a reflective sheet 118, and an optical film 120.

The light source unit 110 includes one or more cold cathode fluorescent lamps 112 and CCFLs and a mounting unit 114.

The cold cathode tube 112 generates light having a predetermined wavelength.

The mounting unit 114 mounts the cold cathode fluorescent lamp 112 and reflects the light generated from the cold cathode fluorescent lamp 112.

The light guide plate 116 controls the reflection conditions of the upper and lower surfaces thereof to evenly spread the light generated from the light source unit 110 over the entire light guide plate 116.

In addition, the light guide plate 116 propagates the diffused light toward the LCD panel 100.

The reflective sheet 118 reflects light passing through the light guide plate 116 toward the light guide plate 116.

The optical film 120 includes a diffusion sheet 122, a prism sheet 124, and a protective sheet 126.

The diffusion sheet 122 diffuses or condenses the light traveling from the light guide plate 116.

The prism sheet 124 collects light diffused or collected by the diffusion sheet 122.

The protective sheet 126 diffuses the light collected by the prism sheet 124 and provides the diffused light to the LCD panel 100.

2A is a cross-sectional view illustrating the diffusion sheet of FIG. 1A.

Referring to FIG. 2A, the diffusion sheet 122 may include a first diffusion part 200, a first support part 202, and a second diffusion part 204.

The diffusion parts 200 and 204 include first beads 206, and focus or diffuse light emitted from the light guide plate 116 using the first beads 206.

However, the first beads 206 cannot condense or diffuse more than a predetermined angle due to material limitations.

In addition, there is no material capable of condensing or diffusing light traveling from the light guide plate 116 above the angle.

2B is a cross-sectional view of the protective sheet of FIG. 1A.

Referring to FIG. 2B, the protective sheet 126 includes a third diffusion part 220, a second support part 222, and a fourth diffusion part 224.

The diffusion parts 220 and 224 include second beads 226, and diffuses the light collected by the prism sheet 124 using the second beads 226.

 However, the second beads 226 may not diffuse more than a predetermined angle due to material limitations.

Disclosure of Invention An object of the present invention is to provide a diffusion sheet, a protective sheet, and a backlight unit including the same, which can focus or diffuse at a predetermined angle or more.

In order to achieve the above object, the backlight unit used in the liquid crystal display device including the liquid crystal display panel according to an exemplary embodiment of the present invention includes a light source unit, a diffusion sheet and a prism sheet. The light source unit generates light of a predetermined wavelength. The diffusion sheet is positioned above the light source unit, includes first beads, and passes light generated from the light source unit. The prism sheet is positioned above the diffusion sheet, and condenses the light passing through the diffusion sheet in the direction of the liquid crystal display panel. Here, each of the first beads includes at least one second bead therein.

A diffusion sheet used in a backlight unit including a light source unit for generating light of a predetermined wavelength according to an exemplary embodiment of the present invention includes a first diffusion part, a support part, and a second diffusion part. The first diffusion part is positioned above the light source part. The support is located above the first diffusion. The second diffusion is located above the support. Here, each of the diffusions includes a plurality of first beads, and each of the first beads includes at least one second bead.

A protective sheet used in a backlight unit including a prism sheet for collecting light generated from a light source unit according to an exemplary embodiment of the present invention includes a first diffuser, a support, and a second diffuser. The first diffusion part is positioned above the prism sheet, and diffuses the light collected from the prism sheet. The support is located above the first diffusion. The second diffuser is positioned above the support, and diffuses the light transmitted through the first diffuser and the support. Here, each of the diffusions includes a plurality of first beads, and each of the first beads has at least one second bead.

Since the diffusion sheet and the protection sheet included in the backlight unit according to the present invention include beads having different beads therein, the light from the light guide plate may be focused or diffused at a predetermined angle or more.

Hereinafter, with reference to the accompanying drawings will be described in detail preferred embodiments of the diffusion sheet, the protective sheet and the backlight unit including them according to the present invention.

3 is a cross-sectional view illustrating a liquid crystal display using a backlight unit according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a liquid crystal display (LCD) includes a liquid crystal display panel 300 and a backlight unit 302.

The LCD panel 300 includes a lower polarizing film 304, an upper polarizing film 306, a lower glass substrate 308, an upper glass substrate 310, a color filter 312, a black matrix 314, and a pixel electrode 316. ), A common electrode 318, a liquid crystal layer 320, and a TFT array 322.

The color filter 312 includes color filters corresponding to red, green, and blue, and generates an image corresponding to red, green, or blue when light is applied.

The TFT array 322 switches the pixel electrode 316 as a switching element.

The common electrode 318 and the pixel electrode 316 arrange molecules of the liquid crystal layer 320 in a predetermined pattern according to a predetermined voltage applied from the outside.

The liquid crystal layer 320 is composed of predetermined molecules, and the molecules are arranged corresponding to the voltage difference between the pixel electrode 316 and the common electrode 318.

As a result, light provided from the backlight unit 302 below is incident on the color filter 312 corresponding to the molecular arrangement of the liquid crystal layer 320.

The backlight unit 302 is positioned under the LCD panel 300 and provides light, for example, white light, to the LCD panel 300.

Referring to FIG. 4, the backlight unit 302 also includes a light source unit 400, a light guide plate 406, a reflective sheet 408, and an optical film 410.

The light source unit 400 includes one or more cold cathode fluorescent lamps (402, CCFL) and a mounting unit 404.

The cold cathode fluorescent lamp 402 generates light having a predetermined wavelength.

Generally, the light is white light.

The light source unit 400 according to another embodiment of the present invention may generate light using a light emitting diode (LED) instead of the cold cathode fluorescent lamp 402.

The mounting unit 304 mounts the cold cathode fluorescent lamp 402 and reflects the light generated from the cold cathode fluorescent lamp 402.

The light guide plate 406 controls the reflection conditions of the upper and lower surfaces thereof to evenly spread the light generated from the light source unit 400 over the entire light guide plate 406.

In addition, the light guide plate 406 advances the diffused light toward the LCD panel 300.

The reflective sheet 408 reflects light passing through the light guide plate 406 toward the light guide plate 406.

The optical film 410 includes a diffusion sheet 412, a prism sheet 414, and a protective sheet 416.

The diffusion sheet 412 diffuses or condenses the light traveling from the light guide plate 406.

Detailed description thereof will be described below with reference to the accompanying drawings.

The prism sheet 414 condenses the light diffused or condensed by the diffusion sheet 412 in the normal direction of the LCD panel 300.

The protective sheet 416 diffuses the light collected by the prism sheet 414 to widen the viewing angle of the LCD panel 300, and provides the diffused light to the LCD panel 300.

In addition, the protective sheet 416 protects the prism sheet 414 and the diffusion sheet 412 which are sensitive to dust and the like.

Hereinafter, the light emission operation of the LCD will be described in detail.

Referring back to FIG. 3, the backlight unit 302 provides the LCD panel 300 with plane light that is white light.

Subsequently, the TFT array 322 switches the pixel electrode 316.

Subsequently, a predetermined voltage difference is applied between the pixel electrode 316 and the common electrode 318, so that the liquid crystal layer 320 is arranged corresponding to the red color filter, the green color filter, and the blue color filter, respectively.

In this case, the amount of light is adjusted while the plane light provided from the backlight unit 302 passes through the liquid crystal layer 320, and the plane light whose light amount is adjusted is provided to the color filter 312.

As a result, the color filter 312 implements an image with a predetermined gray scale.

Specifically, the red color filter, the green color filter, and the blue color filter form one pixel, and the red color filter, the green color filter, and the blue color filter implement a predetermined image by the combination of the light passing through. do.

5A is a cross-sectional view illustrating the diffusion sheet of FIG. 4 in accordance with a preferred embodiment of the present invention.

Referring to FIG. 5A, the diffusion sheet 412 includes a first diffusion part 500, a first support part 502, and a second diffusion part 504.

The first diffuser 500 includes first beads 506, and condenses the light from the light guide plate 406 using the first beads 506.

The first support 502 supports the first diffuser 500 and the second diffuser 504.

The second diffuser 504 includes first beads 506 and condenses the light passing through the first diffuser 500 and the first support 502 using the first beads 506. .

Here, each of the first beads 506 includes at least one second bead 508, as shown in FIG. 5A, and has a refractive index smaller than the second bead 508.

Preferably, each of the first beads 506 has a refractive index of 1.49 and the second bead 508 has a refractive index of 1.49 to 1.58.

In addition, the second bead 508 is located randomly within the first beads 506 and is random in size.

Preferably, the diameters of the first beads 506 are 20 μm and the second beads 508 have a uniform diameter of 2 μm.

According to an embodiment of the present invention, the first beads 506 are each made of polymethyl methacrylate (PMMA), and the second bead 508 is an Methyl ethylene copolymer (Methyl Meta Acrylate). Styrene copolymer, MMA styrene copolymer).

Diffusion units 500 and 504 according to another embodiment of the present invention diffuses the light from the light guide plate 406.

In this case, each of the first beads 506 includes a second bead 508 having a refractive index smaller than itself.

As described above, the diffusion sheet 412 of the present invention, unlike the beads of the conventional diffusion sheet that did not contain any beads therein, each of the first beads 506 including the second bead 508 Include.

Therefore, the diffusion sheet 412 of the present invention can concentrate or diffuse the light traveling from the light guide plate 406 more than the conventional diffusion sheet.

That is, in the conventional diffusion sheet, due to material limitations, the light propagating from the light guide plate could not be focused or diffused more than a predetermined angle.

On the other hand, the diffusion sheet 412 of the present invention includes a second bead 508 inside the first beads 506 to condense or diffuse the light from the light guide plate 406 by a predetermined angle or more.

5B is a cross-sectional view illustrating the prism sheet of FIG. 4 according to an exemplary embodiment of the present invention.

Referring to FIG. 5B, the prism sheet 414 includes a second support part 510 and a prism part 512.

The second support portion 510 includes a prism portion 512.

The prism unit 512 condenses the light collected or diffused by the diffusion sheet 412 in the normal direction of the backlight unit 302.

In addition, prismatic portions having a triangular shape are continuously formed on the prism portion 512.

5C is a cross-sectional view of the protective sheet of FIG. 4 in accordance with a preferred embodiment of the present invention.

Referring to FIG. 5C, the protective sheet 416 may include a third diffuser 520, a third support 522, and a fourth diffuser 524.

The third diffuser 520 includes third beads 526 and diffuses the light collected by the prism sheet 414 using the third beads 526.

The third support part 522 supports the third diffusion part 520 and the fourth diffusion part 524.

The fourth diffuser 524 includes third beads 526 and diffuses the light passing through the third diffuser 520 and the third support 522 using the third beads 526. .

In addition, the fourth diffusion part 524 protects the prism sheet 414 and the diffusion sheet 412 which are sensitive to dust and the like.

Here, each of the third beads 526 includes at least one fourth bead 528 as shown in FIG. 5C.

In addition, each of the third beads 526 has a larger refractive index than the fourth bead 528.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having ordinary knowledge of the present invention will be able to make various modifications, changes, additions within the spirit and scope of the present invention, such modifications, changes and Additions should be considered to be within the scope of the following claims.

As described above, since the diffusion sheet and the protection sheet included in the backlight unit according to the present invention include the first beads having a second bead therein, the light from the light guide plate may be focused or diffused at a predetermined angle or more. There are advantages to it.

Claims (18)

A backlight unit for use in a liquid crystal display device including a liquid crystal display panel, A light source unit generating light having a predetermined wavelength; A diffusion sheet positioned above the light source unit and including first beads and passing light generated from the light source unit; And Located on the diffusion sheet, and includes a prism sheet for condensing the light passing through the diffusion sheet toward the liquid crystal display panel, Each of the first beads includes at least one second bead therein. The backlight unit of claim 1, wherein the second bead has a refractive index greater than that of the first bead. The backlight unit of claim 1, wherein each of the first beads is made of polymethylmethacrylate (PMMA). 4. The backlight unit of claim 3, wherein the second bead is made of MMA styrene copolymer (MMA styrene copolymer). The method of claim 1, wherein the backlight unit, A protective sheet positioned on the prism sheet, including third beads, and diffusing light collected by the prism sheet using the third beads, And each of the third beads includes at least one fourth bead. The backlight unit of claim 5, wherein the fourth bead has a smaller refractive index than the third bead. The backlight unit of claim 1, wherein the second bead has a refractive index of 1.49 to 1.58. The backlight unit of claim 1, wherein each of the first beads has a diameter of 20 μm, and the second beads have a diameter of 2 μm. The backlight unit of claim 1, wherein the second bead has a refractive index smaller than that of the first bead. A diffusion sheet for use in a backlight unit including a light source unit for generating light of a predetermined wavelength, A first diffusion part positioned above the light source part; A support located above the first diffusion; And Including a second diffusion portion located above the support, And each of the diffusion parts includes a plurality of first beads, and each of the first beads has at least one second bead. The diffusion sheet of claim 10, wherein the second bead has a refractive index greater than that of the first beads. The diffusion sheet of claim 10, wherein each of the first beads is made of polymethyl methacrylate (PMMA). 13. The diffusion sheet of claim 12, wherein the second bead is made of MMA styrene copolymer (MMA styrene copolymer). 11. The diffusion sheet of claim 10, wherein the second bead has a refractive index of 1.49 to 1.58. The diffusion sheet of claim 10, wherein each of the first beads has a diameter of 20 μm, and the second beads have a diameter of 2 μm. The diffusion sheet of claim 10, wherein the second bead has a refractive index smaller than that of the first beads. A protective sheet for use in a backlight unit including a prism sheet for collecting light generated from a light source unit, A first diffusion part positioned on an upper portion of the prism sheet and diffusing light collected from the prism sheet; A support located above the first diffusion; And Located in the upper portion of the support, including a first diffuser and a second diffuser for diffusing light passing through the support, Each of the diffusion parts includes a plurality of first beads, and each of the first beads has at least one second bead. 18. The protective sheet of claim 17, wherein the second bead has a refractive index smaller than that of the first beads.

Images