KR20090053518A - Back light unit and comprising of liquid crystal display device - Google Patents

Abstract

The present invention includes a light source, a diffuser plate positioned on the light source, and an optical film positioned on the diffuser plate, wherein the optical film includes a backlight unit including a diffuser sheet and a micro lens film positioned on the diffuser sheet. to provide.

Backlight unit

Description

Back light unit and comprising a liquid crystal display device including the same

The present invention relates to a backlight unit and a liquid crystal display including the same.

In general, a liquid crystal display classified into a light receiving display device may include a backlight unit disposed below the liquid crystal panel to provide light to the liquid crystal panel in addition to the liquid crystal panel displaying an image.

The backlight unit may include a light source, an optical film, and the like to provide light to the liquid crystal panel. Here, the optical film may include a diffusion sheet, a prism sheet, a protective sheet, and the like.

In the conventional backlight unit having the above configuration, the light emitted from the light source can be diffused through the diffusion sheet and then focused by the prism sheet.

As such, since diffusion and condensation of the light emitted from the light source are made by a diffusion sheet, a prism sheet, and the like, which are separately manufactured, many limitations may occur in achieving reduction in manufacturing cost and light weight of the backlight unit.

Therefore, in recent years, research is being conducted to replace the diffusion sheet and the prism sheet using a micro lens sheet having both light diffusion and light collection functions.

The micro lens sheet may diffuse and focus light emitted from the light source through the micro lens formed on the substrate.

However, when a microlens sheet is used instead of the diffusion sheet and the prism sheet, there is a problem that the diffusion or condensing efficiency of the microlens sheet may be deteriorated.

Therefore, there is a problem in that the brightness or contrast ratio (CR) characteristics of the backlight unit including the micro lens sheet are deteriorated.

Accordingly, the present invention provides a backlight unit capable of improving the brightness or contrast ratio of the backlight unit and a liquid crystal display including the same.

In order to achieve the above object, the backlight unit according to an embodiment of the present invention includes a light source, a diffusion plate positioned on the light source and an optical film located on the diffusion plate, the optical film is a diffusion sheet And it may include a micro lens film located on the diffusion sheet.

In addition, in order to achieve the above object, the liquid crystal display device according to an embodiment of the present invention is a light source, a diffusion plate located on the light source, an optical film located on the diffusion plate, positioned on the optical film And a liquid crystal panel, wherein the optical film may include a diffusion sheet and a micro lens film positioned on the diffusion sheet.

In addition, in order to achieve the above object, the backlight unit according to an embodiment of the present invention includes a light source, a diffusion plate located on the light source and an optical film located on the diffusion plate, the optical film is It may include two or more micro lens films.

In addition, in order to achieve the above object, the liquid crystal display device according to an embodiment of the present invention is a light source, a diffusion plate located on the light source, an optical film located on the diffusion plate and positioned on the optical film. It includes a liquid crystal panel, the optical film may include two or more micro lens film.

In addition, in order to achieve the above object, the backlight unit according to an embodiment of the present invention includes a light source, a diffusion plate located on the light source and an optical film located on the diffusion plate, the optical film is It may include a micro lens film and a prism sheet positioned on the micro lens film.

In addition, in order to achieve the above object, the liquid crystal display device according to an embodiment of the present invention is a light source, a diffusion plate located on the light source, an optical film located on the diffusion plate and positioned on the optical film. It includes a liquid crystal panel, wherein the optical film may include a micro lens film including an embossed hemisphere and a prism sheet positioned on the micro lens film.

The backlight unit and the liquid crystal display including the same according to the present invention have an advantage of improving brightness or contrast ratio of the backlight unit.

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

<First Embodiment>

1 is a cross-sectional view illustrating a backlight unit according to a first embodiment of the present invention.

Referring to FIG. 1, the backlight unit 100 according to the first embodiment of the present invention may be provided in a liquid crystal display.

The backlight unit 100 is disposed on the light source 110, the reflector 120 positioned below the light source 110, the diffuser plate 140 positioned on the light source 110, and the diffuser plate 140. It includes an optical film 150, the optical film 150 is located on the diffusion sheet 151 and the diffusion sheet 151, a micro lens film including a substrate 156 and a micro lens unit 157 155 may include.

The light source 110 may generate light by using driving power applied from the outside, and may serve to emit the generated light upward.

The light source 110 includes a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Elextrode Fluorescent Lamp (EEFL), and a Light Emitting Diode. : LED), but is not limited thereto.

The reflector 120 is positioned under the light source 110 to reflect the light incident from the light source 110 to the front. Here, the reflector 120 may be made of a highly reflective material in order to increase the reflection efficiency and may coat silver (Ag) on the surface thereof.

The diffusion plate 140 may be positioned on the light source 110, and may diffuse or condense the light incident from the light source 110 to the top to make the luminance uniform and to widen the viewing angle. The diffusion plate 140 may be any one of an acrylic plate and a polymethyl methacrylate (PMMA), but is not limited thereto.

The optical film 150 may be disposed on the diffusion sheet 151 and the diffusion sheet 151, and may include a micro lens film 155 including a substrate 156 and a micro lens unit 157.

The diffusion sheet 151 may be positioned on the diffusion plate 140 to uniformly diffuse light onto the entire surface. The diffusion sheet 151 may be polyester or polycarbonate, but is not limited thereto.

The micro lens film 155 may include a substrate 156 and a micro lens unit 157.

The substrate 156 serves to transmit light incident from the bottom of the micro lens film 155. To this end, the substrate 156 may be made of a transparent material. At this time, the substrate 156 may be made of a thin thickness of 100 to 350㎛. Therefore, the substrate 156 can be bent like a film having excellent workability.

The micro lens unit 157 may include an embossed hemispherical surface on one surface of the substrate 156. That is, the micro lens unit 157 may protrude in an embossed hemispherical shape on one surface of the substrate 156. In this case, the micro lens unit 157 may be formed on one surface of the substrate 156 through a roll to roll manufacturing method due to the thin thickness of the substrate 156.

As described above, when the microlens 157 is formed to have an embossed hemisphere, some of the light incident from the lower portion of the microlens film 155 is uniformly refracted at all azimuth angles in the hemisphere and thus the microlens portion It is possible to penetrate 157. Therefore, some of the light incident from the bottom of the micro lens film 155 may be uniformly diffused toward the top and may be focused.

The micro lens unit 157 may be made of a transparent polymer resin to transmit light incident from the outside. Here, the polymer resin may be any one selected from the group consisting of acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate.

The micro lens film 155 may further include a protective layer 158. The protective layer 158 may be formed on the bottom surface of the micro lens film 155 to improve heat resistance of the micro lens film 155 and to diffuse light propagated from the light source 110.

The protective layer 158 may include a plurality of beads 158b in the resin 158a. Here, the resin 158a may use acrylic resin that is excellent in heat resistance and resistant to scratches. The acrylic resin may be polyacrylate or polymethacrylate. In addition, the beads 158b may be included in an amount of 10 to 50 parts by weight, preferably 30 parts by weight, based on the resin 158a.

The protective layer 158 may be formed to a thickness of 2 to 3㎛.

The protective layer 158 as described above may prevent the micro lens film 155 from being deformed by heat generated from the light source 110. That is, wrinkles may be prevented from occurring in the microlens film 155 by the heat resistant resin 158a, and even if the microlens film 155 is deformed at a high temperature, the microlens film 155 is returned to its original state at room temperature. ) The resilience to return to the shape is excellent.

As described above, in the first embodiment of the present invention, by including a diffuser plate on a light source and a micro lens film including a substrate and a micro lens unit on the diffuser plate, light incident from the light source passes through the diffuser plate. Diffused, the diffused light can be diffused and collected through the micro lens film.

Therefore, the liquid crystal display device including the backlight unit according to the first embodiment of the present invention has an advantage of improving luminance by improving light diffusion and condensing characteristics of the backlight unit.

Second Embodiment

2 is a cross-sectional view illustrating a backlight unit according to a second embodiment of the present invention.

Referring to FIG. 2, the backlight unit 200 according to the second embodiment of the present invention may be provided in the liquid crystal display device.

The backlight unit 200 includes a light source 210, a reflector plate 220 positioned below the light source 210, a diffuser plate 240 positioned on the light source 210, and a diffuser plate 240. The optical film 250 may be included, and the optical film 250 may include a first micro lens film 256 and a second micro lens film 259.

The light source 210 may generate light by using driving power applied from the outside, and may serve to emit the generated light upward.

The light source 210 includes a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Elextrode Fluorescent Lamp (EEFL), and a Light Emitting Diode. : LED), but is not limited thereto.

The reflector 220 is positioned under the light source 210 to reflect the light incident from the light source 210 to the front. Here, the reflector plate 220 may be made of a highly reflective material in order to increase the reflection efficiency, and may be coated with silver (Ag) on its surface.

The diffusion plate 240 may be positioned on the light source 210, and may diffuse or condense the light incident from the light source 210 to the top to make the luminance uniform and to widen the viewing angle. The diffusion plate 240 may be any one of an acrylic plate and a polymethyl methacrylate (PMMA), but is not limited thereto.

The optical film 250 may include a first micro lens film 256 and a second micro lens film 259.

The first micro lens film 256 may include a first substrate 251 and a first micro lens unit 252.

The first base material 251 transmits light incident from the lower portion of the first micro lens film 256. To this end, the first substrate 251 may be made of a transparent material. At this time, the first base material 251 may be made of a thin thickness of 100 to 350㎛. Therefore, the first base material 251 can be bent well like a film having excellent workability.

The first micro lens unit 252 may include an embossed hemispherical surface on one surface of the first substrate 251. That is, the first micro lens unit 252 may protrude in a hemispherical shape on one surface of the first substrate 251. In this case, the first micro lens unit 252 may be formed on one surface of the first substrate 251 through a roll to roll manufacturing method due to the thin thickness of the first substrate 251.

As described above, when the first micro lens unit 252 is formed to have an embossed hemisphere, some of the light incident from the lower portion of the first micro lens film 256 is uniformly refracted at all azimuth angles in the hemisphere. Thus, the first micro lens unit 252 may be transmitted.

Accordingly, some of the light incident from the lower portion of the first micro lens film 256 may be uniformly diffused toward the upper portion and may be collected. The first micro lens unit 252 is transparent to transmit light incident from the outside. It may be made of a polymer resin. Here, the polymer resin may be any one selected from the group consisting of acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate.

The first micro lens film 256 may further include a protective layer 253. The protective layer 253 may be formed on the bottom surface of the first micro lens film 256 to improve heat resistance of the micro lens film and to diffuse light propagated from the light source.

The protective layer 253 may include a plurality of beads 254b in the resin 254a. Here, the resin 254a may use acrylic resin that is excellent in heat resistance and resistant to scratches. The acrylic resin may be polyacrylate or polymethacrylate. In addition, the beads 254b may be included in an amount of 10 to 50 parts by weight, preferably 30 parts by weight, based on the resin 254a.

The protective layer 253 may be formed to a thickness of 2 to 3㎛.

The second micro lens film 259 may include a second substrate 257 and a second micro lens unit 258. Since the second substrate 257 and the second micro lens unit 258 may have the same configuration as the first substrate 251 and the first micro lens unit 252 described above, description thereof will be omitted.

In the second embodiment of the present invention, a structure in which the protective layer is included in the first micro lens film and the protective layer is not included in the second micro lens film is described as an example. However, the protective layer may be included in both the first micro lens film and the second micro lens film. Alternatively, the protective layer may not be included in both the first micro lens film and the second micro lens film. In addition, a protective layer may be included on one surface of either the first micro lens film or the second micro lens film.

As described above, in the second embodiment of the present invention, by including the diffuser plate on the light source and the two or more micro lens films on the diffuser plate, light incident from the light source passes through the two or more micro lens films. Can be diffused and collected.

Therefore, the LCD including the backlight unit according to the second exemplary embodiment of the present invention has an advantage of improving luminance by improving light diffusion and condensing characteristics of the backlight unit.

Third Embodiment

3 is a cross-sectional view illustrating a backlight unit according to a third embodiment of the present invention.

Referring to FIG. 3, the backlight unit 300 according to the third embodiment of the present invention may be provided in the liquid crystal display device.

The backlight unit 300 may include a light source 310, a reflection plate 320 positioned below the light source 310, a diffusion plate 340 positioned on the light source 310, and a diffusion plate 340. It may include an optical film 350.

The optical film 350 may include a micro lens film 360 and a prism sheet 370 positioned at the micro lens film 360, and further include a protective sheet 380 on the prism sheet 370. It may include.

The light source 310 may generate light by using driving power applied from the outside, and may serve to emit the generated light upward.

The light source 310 includes a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Elextrode Fluorescent Lamp (EEFL), and a Light Emitting Diode. : LED), but is not limited thereto.

The reflector 320 is positioned under the light source 310 to serve to reflect the light incident from the light source 310 to the front. Here, the reflector 320 may be made of a material having high reflectivity in order to increase reflection efficiency, and may coat silver (Ag) on the surface thereof.

The diffusion plate 340 may be positioned on the light source 310, and may diffuse or condense the light incident from the light source 310 to the top to make the luminance uniform and to widen the viewing angle.

The diffusion plate 340 may be any one of an acrylic plate and a polymethyl methacrylate (PMMA), but is not limited thereto.

The optical film 350 may include a micro lens film 360 and a prism sheet 370 positioned at the micro lens film 360, and further include a protective sheet 380 on the prism sheet 370. It may include.

The micro lens film 360 may include a substrate 361 and a micro lens unit 362.

The substrate 361 serves to transmit light incident from the bottom of the micro lens film 360. To this end, the substrate 361 may be made of a transparent material. At this time, the substrate 361 may be made of a thin thickness of 100 to 350㎛. Therefore, the substrate 361 can be bent as well as a film having excellent workability.

The micro lens unit 362 may include an embossed hemispherical surface on one surface of the substrate 361. That is, the micro lens unit 362 may protrude in an embossed hemispherical shape on one surface of the substrate 361. In this case, the micro lens unit 362 may be formed on one surface of the substrate 361 through a roll to roll manufacturing method due to the thin thickness of the substrate 361.

As described above, when the micro lens unit 362 is formed to have an embossed hemispherical surface, some of the light incident from the lower portion of the micro lens film 360 is uniformly refracted at all azimuth angles in the hemisphere and thus the micro lens unit It is possible to penetrate (362). Therefore, some of the light incident from the bottom of the micro lens film 360 may be uniformly diffused toward the top and may be focused.

The micro lens unit 362 may be made of a transparent polymer resin to transmit light incident from the outside. Here, the polymer resin may be any one selected from the group consisting of acrylic, polycarbonate, polypropylene, polyethylene, and polyethylene terephthalate.

The micro lens unit 362 may further include a protective layer 363. The protective layer 363 may be formed on the bottom surface of the micro lens film 360 to improve heat resistance of the micro lens film 360 and to diffuse light from the light source 310.

The protective layer 363 may include a plurality of beads 364b in the resin 364a. Here, the resin 364a may use acrylic resin that is excellent in heat resistance and resistant to scratches. The acrylic resin may be polyacrylate or polymethacrylate. In addition, the beads 364b may be included in an amount of 10 to 50 parts by weight, preferably 30 parts by weight, based on the resin 364a.

The protective layer 363 may be formed to a thickness of 2 to 3㎛.

The protective layer as described above may prevent the micro lens film from being deformed by the heat generated from the light source. That is, wrinkles may be prevented from occurring in the microlens film by the resin having high heat resistance, and even when the microlens film is deformed at a high temperature, the restoring force of returning to the original microlens film shape at room temperature is excellent.

The prism sheet 370 is positioned on the micro lens film 360. The prism sheet 370 may serve to condense the light incident through the micro lens film 360 upwards. Accordingly, most of the light passing through the prism sheet 370 proceeds perpendicularly to the plane of the liquid crystal panel to have a uniform luminance distribution.

4A and 4B are perspective views illustrating a prism sheet according to an embodiment of the present invention.

4A and 4B, the prism sheet 370 may include a substrate 371 and a prism pattern 372. Since the substrate 371 should be able to transmit light incident from a light source, the substrate 371 may be made of any one selected from the group consisting of a light transmissive material, for example, polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polystyrene, and polyepoxy. However, the present invention is not limited thereto.

The prism pattern 372 may serve to condense the light incident from the light source.

The prism pattern 372 may have a triangular cross section. In addition, the prism pattern 372 may be linearly formed along the length direction of the prism pattern 372, but may be formed in a triangular prism bar shape in appearance, but is not limited thereto. In the prism pattern 372, a concave portion may be formed in the protruding portion on the hill or the inclined surface of the prism pattern 372. Such protrusions or recesses are more effective in condensing light incident from the light source.

In addition, the peaks of the prism pattern 372 may be formed in a straight line, and may be formed in a curved shape having a constant or irregular amplitude. In addition, the valley of the prism pattern 372 may be formed in a straight line or a curved shape having an irregular amplitude like a mountain, but is not limited thereto.

In addition, the height of the peak of the prism pattern 372 may be formed in a regular or irregular curved shape in the longitudinal direction of the prism pattern 372, but is not limited thereto.

The protective sheet 380 is positioned on the prism sheet 370. The protective sheet 380 may be positioned on the prism sheet 370 to prevent the prism sheet 370 from being scratched and to widen the viewing angle narrowed by the prism sheet 370.

As described above, the third embodiment of the present invention includes an optical film including a diffuser plate on a light source, a micro lens film and a prism sheet on the diffuser plate, and further comprising a protective sheet on the prism sheet. Thus, light incident from the light source can be diffused and collected through the micro lens film and the prism sheet. In addition, there is an advantage that the viewing angle is wider by further including a protective sheet.

Therefore, the liquid crystal display device including the backlight unit according to the third embodiment of the present invention has the advantage of improving the light diffusion and condensing characteristics of the backlight unit to improve luminance and to enlarge a viewing angle.

5 is a cross-sectional view of a liquid crystal display including a backlight unit according to embodiments of the present invention.

Referring to FIG. 5, the liquid crystal display 500 may include a liquid crystal panel and a backlight unit 400. The backlight unit 400 may be a direct type or edge type backlight unit.

The backlight unit 400 may include a light source, a diffuser plate positioned on the light source, and an optical film positioned on the diffuser plate, as in the first embodiment described above. Here, the optical film may include a micro lens film positioned on the diffusion sheet and the diffusion sheet and including an embossed hemisphere.

Unlike this, the backlight unit 400 may include a light source, a diffusion plate positioned on the light source, and an optical film positioned on the diffusion plate, as in the above-described second embodiment. Here, the optical film may include two or more micro lens films including an embossed hemisphere.

In addition, the backlight unit 400 may include a light source, a diffuser plate positioned on the light source, and an optical film positioned on the diffuser plate, as in the above-described third embodiment. Here, the optical film may include a micro lens film including an embossed hemisphere and a prism sheet positioned on the micro lens film, and may further include a protective sheet on the prism sheet.

Hereinafter, since the backlight unit included in the liquid crystal display device is the same as the backlight unit according to the first to third embodiments, only the liquid crystal display device will be described below.

The LCD 500 includes a lower polarizing film 520a, an upper polarizing film 520b, a lower glass substrate 530a, an upper glass substrate 530b, a color filter 590, a black matrix 580, and a pixel electrode. 550, the common electrode 560, the liquid crystal layer 570, and the thin film transistor 340. The color filter 560 may correspond to R (red), G (green), and B (blue). A filter may be included, and when light is applied, an image corresponding to each of the filters may be generated.

The common electrode 560 and the pixel electrode 550 may arrange molecules of the liquid crystal layer 570 according to a predetermined voltage applied from the outside. The pixel electrode 550 may be switched by the thin film transistor 540.

The liquid crystal layer 570 may be formed of predetermined molecules, and the molecules may be arranged corresponding to the voltage difference between the pixel electrode 550 and the common electrode 560.

As a result, light incident from the backlight unit may be incident on the color filter corresponding to the molecular arrangement of the liquid crystal layer 570.

The backlight unit 400 may be disposed under the liquid crystal display 500 and may provide light to the liquid crystal panel.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the above-described technical configuration of the present invention may be embodied in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. In addition, all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention.

1 is a cross-sectional view of a backlight unit according to a first embodiment of the present invention.

2 is a cross-sectional view of a backlight unit according to a second embodiment of the present invention;

3 is a cross-sectional view of a backlight unit according to a third embodiment of the present invention.

4A and 4B are perspective views illustrating a prism sheet according to an embodiment of the present invention.

5 is a cross-sectional view of an LCD including a backlight unit according to embodiments of the present invention.

Explanation of symbols on the main parts of the drawings

110: light source 120: reflector

140: diffusion plate 150: optical film

151: diffusion sheet 155: micro lens film

156: substrate 157: micro lens unit

158: protective layer

Claims (16)

Light source; A diffusion plate positioned on the light source; And It includes an optical film located on the diffusion plate, The optical film includes a diffusion sheet and a micro lens film positioned on the diffusion sheet. The method of claim 1, The micro lens film comprises a micro lens unit including a base and an embossed hemisphere. The method of claim 2, The backlight unit further comprises a protective layer on one surface of the substrate. The method of claim 3, wherein The protective layer includes a plurality of beads and resin. Light source; A diffusion plate positioned on the light source; An optical film positioned on the diffusion plate; It includes a liquid crystal panel located on the optical film, The optical film includes a diffusion sheet and a micro lens film positioned on the diffusion sheet. Light source; A diffusion plate positioned on the light source; And It includes an optical film located on the diffusion plate, The optical film is a backlight unit comprising two or more micro lens film. The method of claim 6, The backlight unit further comprises a protective layer on one surface of the at least one micro lens film of the micro lens film. The method of claim 7, wherein The protective layer includes a plurality of beads and resin. Light source; A diffusion plate positioned on the light source; An optical film positioned on the diffusion plate; And It includes a liquid crystal panel positioned on the optical film, The optical film includes a liquid crystal display device comprising two or more micro lens film. Light source; A diffusion plate positioned on the light source; And It includes an optical film located on the diffusion plate, The optical film includes a micro lens film and a prism sheet positioned on the micro lens film. The method of claim 10, The micro lens film includes a base and a micro lens unit, The backlight unit further comprises a protective layer on one surface of the substrate. The method of claim 11, The protective layer includes a plurality of beads and resin. The method of claim 10, The prism sheet further includes a prism pattern, The peak or valley of the prism pattern is a straight line backlight unit. The method of claim 13, The peak or valley of the prism pattern is a curved backlight unit having a constant amplitude. The method of claim 10, The backlight unit further comprises a protective sheet on the prism sheet. Light source; A diffusion plate positioned on the light source; An optical film positioned on the diffusion plate; And It includes a liquid crystal panel positioned on the optical film, The optical film includes a micro lens film and a prism sheet positioned on the micro lens film.

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