KR20070021378A - Back light assembly and liquid crystal display having the same - Google Patents

Abstract

Disclosed are a backlight assembly and a display device having the same, which can reduce manufacturing costs. The lamp provides light. The first diffuser plate includes a first flat plate base portion and a plurality of lenticular lens patterns protruding from the surface of the first flat plate base portion and is disposed on the lamp to diffuse light provided from the lamp. The second diffuser plate includes a plurality of prismatic patterns having an angle of at least 100 degrees and less than 180 degrees on the surface of the second plate base portion and the second plate base portion, and are disposed on the first diffuser plate and exit from the first diffuser plate. The collected light. Accordingly, by implementing the first and second diffusion plates for diffusing and condensing the light incident from the light source, the overall brightness and the uniformity of the brightness can be improved even if the number of optical sheets is reduced.

LCD, Optical Sheet, Diffusion Plate, Lenticular Lens, Prism Pattern

Description

BACK LIGHT ASSEMBLY AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

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

FIG. 2 is a perspective view illustrating the first and second diffusion plates illustrated in FIG. 1.

FIG. 3 is a cross-sectional view illustrating a shape of a unit lenticular lens of the first diffusion plate illustrated in FIG. 1.

4 is a cross-sectional view illustrating a shape of a unit prism acid of the second diffusion plate illustrated in FIG. 1.

5 is a conceptual diagram illustrating an optical path of the second diffusion plate illustrated in FIG. 1.

FIG. 6 is a conceptual diagram illustrating a diffusion plate manufacturing apparatus for manufacturing the second diffusion plate illustrated in FIG. 1.

FIG. 7 is an enlarged view of the region A shown in FIG. 6.

8 is an exploded perspective view illustrating a display device having a backlight assembly according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

110: flat fluorescent lamp 120: reflector

130: first diffusion plate 140: second diffusion plate

200: diffuser plate manufacturing apparatus 210: tank

220: extruder 230: roller portion

310: storage container 330: inverter

400: display unit

The present invention relates to a backlight assembly and a liquid crystal display having the same, and more particularly, to a backlight assembly and a liquid crystal display having the same to reduce the manufacturing cost.

Liquid crystal display devices used in notebooks, portable terminals, and the like cannot be used in a dark place because they are non-luminous. Therefore, the backlight assembly which irradiates light uniformly to the display surface on a liquid crystal panel is used.

The backlight assembly of the liquid crystal display device should be lightweight, thin to avoid affecting the thinness of the liquid crystal, and high luminance uniformity. The backlight assembly having this feature is divided into a direct type and an edge type. The direct type backlight assembly is mainly employed in a large LCD, and the edge type backlight assembly is employed in a small LCD.

In general, the backlight assembly requires a reflector, a diffuser plate, a diffusion sheet, a prism sheet, and a dual bright enhancement film (DBEF) to uniformly radiate linear light uniformly throughout the liquid crystal panel. There is a limit to reduce the, and there is a problem that does not meet the trend that the thickness of the backlight assembly is required.

In addition, there is a problem that the manufacturing cost is increased by using a plurality of optical sheets. Among them, high brightness reinforcement film (DBEF), which reduces the loss of light and increases brightness, and prism sheet, which secures a wide viewing angle by adjusting the angle of light, occupy a large part of the manufacturing cost.

However, when the high brightness reinforcement film (DBEF) or the prism sheet is removed to reduce the manufacturing cost, there is a problem in that the brightness of the display screen is considerably reduced. Accordingly, even if the high brightness reinforcement film (DBEF) or prism sheet is removed, a backlight assembly capable of securing a certain level, for example, luminance of 500 nits or more is required.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional point, and an object of the present invention is to provide a backlight assembly having a reduced thickness while securing a predetermined level of brightness while reducing the manufacturing cost of a display device.

Another object of the present invention is to provide a liquid crystal display device having the above-described backlight assembly.

The backlight assembly according to an embodiment for realizing the object of the present invention includes a lamp, a first diffuser plate and a second diffuser plate. The lamp provides light. The first diffuser plate includes a first flat plate base portion and a plurality of lenticular lens patterns protruding from a surface of the first flat plate base portion, and is disposed on the lamp to diffuse light provided from the lamp. The second diffuser plate includes a plurality of prismatic patterns having an angle of at least 100 degrees and less than 180 degrees on a surface of the second flat plate base portion and the second flat plate base portion, and are disposed on the first diffuser plate to be disposed on the first flat plate. Condenses the light emitted from the diffuser plate.

According to another exemplary embodiment, a liquid crystal display device includes a display panel and a backlight assembly. The display panel displays an image using light. The backlight assembly includes a lamp for providing light, a first diffusion plate that emits light emitted from the lamp by first diffusion, and a second diffusion plate disposed on the second diffusion plate to collect and diffuse the first diffused light. It includes a second diffusion plate.

According to such a backlight assembly and a liquid crystal display having the same, by implementing the first and second diffusion plates for diffusing and condensing the light incident from the light source, the overall brightness and luminance uniformity are improved even if the number of optical sheets is reduced. You can.

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

1 is a cross-sectional view illustrating a backlight assembly according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating the first and second diffusion plates illustrated in FIG. 1.

1 and 2, the backlight assembly 100 includes a planar fluorescent lamp 110, a reflecting plate 120, a first diffusion plate 130, and a second diffusion plate 140.

The flat fluorescent lamp 110 includes a lamp body which is divided into a plurality of discharge spaces to generate light. Specifically, in order to emit light in the form of a plane, the lamp body has a rectangular shape as viewed from above. The lamp body generates a plasma discharge in the discharge spaces by the discharge voltage applied from the outside, and converts the ultraviolet rays generated by the plasma discharge into visible light to be emitted to the outside. Since the lamp body has a large light emitting area, the internal space is divided into a plurality of discharge spaces to improve the light emitting efficiency and uniform light emission. The lamp body includes two substrates coupled to each other to form a plurality of discharge spaces.

The reflector 120 is disposed under the flat fluorescent lamp 110 to reflect visible light provided from the flat fluorescent lamp 110. When the reflective material having excellent reflection efficiency is coated on the lower substrate of the flat fluorescent lamp 110, the reflective plate 120 may be omitted.

Referring to FIG. 2, the first diffuser plate 130 includes a first flat plate base part 132 serving as a support layer and a lenticular lens pattern 134 formed on the first flat plate base part 132. The lenticular lens pattern 134 extends in the x-axis direction parallel to the discharge space and is arranged in the y-axis direction perpendicular to the discharge space.

The first flat base portion 132 is formed of a transparent plastic plate having a thickness of 1 to 3 mm, and the material of the plastic plate is transparent and has a high refractive index polycarbonate-serises resin (PC), poly Materials such as polymethylmethacrylate-serises resin (PMMA), methacrylate-styrene copolymers (MS) and the like are used.

The second diffusion plate 140 includes a second flat plate base part 142 serving as a support layer and a prism pattern 144 formed on the second flat plate base part 142. The prism pattern 144 extends in the x-axis direction and extends in the y-axis direction. The second diffuser plate 140 is made of a transparent plastic plate having a thickness of 0.5 ± 0.05 mm, and has an intermediate value between a general optical film and an optical plate thickness. The transparent plastic plate may be made of a transparent, high refractive index polycarbonate-series resin (PC), polymethylmethacrylate-serises resin (PMMA), methacrylate-styrene copolymer Use a material such as polymer (methacrylate-styrene copolymer, MS).

3 is a cross-sectional view illustrating a shape of a unit lenticular lens of the first diffusion plate 130 illustrated in FIG. 1 .

Referring to FIG. 3, the unit lenticular lens has a pitch w of 100 μm to 200 μm, forms the same inclination angle (θ ₁ = θ ₂ ) of 44 ° to 46 ° as the surface of the first flat plate base part. The angle θ ₃ is between 88 ° and 92 °. The radius of curvature r has a thickness of 35 μm to 75 μm.

4 is a cross-sectional view illustrating the shape of the unit prism acid of the second diffusion plate 140 illustrated in FIG. 1 .

Referring to FIG. 4, the unit prism mountain 144 is defined as first and second inclination angles θ1 and θ2 formed with the second flat base portion 142, and an angle θ3 of a vertex of the unit prism mountain. The pitch w of the unit prism acid 144 is 100 µm to 200 µm. The first inclination angle θ1 and the second inclination angle θ2 are the same, and the angle θ3 of the vertex has an angle of 100 ° or more and less than 180 °. The vertex of the unit prism acid has a round shape, and the radius of curvature r of the round shape is 30 μm to 40 μm.

FIG. 5 is a conceptual diagram illustrating an optical path by a unit prism acid of the second diffusion plate illustrated in FIG. 1.

1 and 5, light diffused and scattered from the first diffuser plate 130 is incident to the second diffuser plate 140. Light incident on the second diffusion plate 140 is refracted while passing through the prism pattern 144, and is focused in a vertical direction toward the liquid crystal display panel 400.

Specifically, if the light incident on the normal of the second flat plate base portion 142 of the second diffuser plate 140 has an incident angle of 60 degrees, the light emitted by the refraction has an exit angle of approximately 30 degrees. Have Further, if the light incident on the normal has an angle of incidence of approximately 40 degrees, the light emitted by the above refraction has an emission angle of approximately 25 degrees. Further, if the light incident on the normal has an angle of incidence of approximately 30 degrees, the light emitted by the above refraction has an emission angle of approximately 19 degrees. Of course, since the vertex portion of the prism pattern 144 is rounded at a predetermined curvature, the vertex portion 144 serves to scatter incident light.

As such, the inclined surface of the prism pattern formed on the second diffusion plate according to the present invention collects the light provided from the lower part and scatters the light from the apex, thereby securing the viewing angle and improving the front brightness.

FIG. 6 is a conceptual diagram illustrating a diffusion plate manufacturing apparatus for manufacturing the second diffusion plate illustrated in FIG. 1. FIG. 7 is an enlarged view of the region A shown in FIG. 6.

6 and 7, the diffusion plate manufacturing apparatus 200 includes a tank 210, an extruder 220, and a roller unit 230.

The tank 210 accommodates the transparent plastic material before melting and solidifying from 50 ° C. to 80 ° C., and injects the received transparent plastic material into the extruder 220.

The extruder 220, including the injection hole 222 and the body 224, as the transparent plastic material is injected, is formed in a plate shape and provided to the roller unit 230.

The roller unit 230 includes first, second, third and fourth rollers 232, 234, 236, and 238. The first roller 232 rotates clockwise, and the second roller 234 rotates counterclockwise. The third roller 236 rotates clockwise, and the fourth roller 238 rotates counterclockwise. The plastic plate provided by the extruder 220 passes through a space between the first and second rollers 232 and 234 which rotate in different directions, and then rotates in the third and fourth rollers having different directions. Pass the space between (236,238). In this case, since the prism pattern is formed on the fourth roller 238 as shown in FIG. 7, the prism pattern is formed on the plastic plate passing through the space between the third and fourth rollers 236 and 238. do. The prism pattern includes a V-shaped groove having an angle of at least 100 °.

In the above, a series of processes for forming the prism acid on the surface of the plastic plate using the roller portion have been described. However, a person skilled in the art may form the prism acid on the surface using a stamper (or an implant member). Of course, a prism pattern having a shape corresponding to the prism pattern of the second diffusion plate is formed on one surface of the stamper. When the stamper is pressed onto the plastic plate provided from the extruder, the second diffusion plate having the prism pattern is formed. Are manufactured.

As such, the extrusion process and the patterning process can proceed continuously in the extrusion line without a separate step, it is possible to reduce the manufacturing cost.

8 is an exploded perspective view of a liquid crystal display having a backlight assembly according to an exemplary embodiment of the present invention.

Referring to FIG. 8, the liquid crystal display device 500 includes a flat panel fluorescent lamp 110, a first diffusion plate 130, a second diffusion plate 140, a storage container 310, an inverter 330, and a display unit ( 400). In comparison with FIG. 1, the same reference numerals are assigned to the same components for the convenience of description.

The flat plate fluorescent lamp 110 is divided into a plurality of discharge spaces to generate a lamp body, an external electrode formed to intersect the discharge spaces at both ends of the lamp body and coupled to the lamp body in contact with the external electrode Included auxiliary electrode.

Specifically, the lamp body is a rectangular plane when viewed from above, in order to emit light in the form of a plane. The lamp body generates a plasma discharge in the discharge spaces by the discharge voltage applied from the inverter 330 to the external electrode, and converts the ultraviolet rays generated by the plasma discharge into visible light to be emitted to the outside. Since the lamp body has a large light emitting area, the internal space is divided into a plurality of discharge spaces to improve the light emitting efficiency and uniform light emission. The lamp body includes a first substrate and a second substrate coupled to each other to form a plurality of discharge spaces. In FIG. 8, a flat fluorescent lamp is shown as an example of a lamp, but a person skilled in the art may also use a plurality of Cold Cathode Fluorescent Lamps (CCFLs) or External Electrode Fluorescent Lamps (EEFLs). Is self-explanatory.

In the storage container 310, a storage space for storing the flat fluorescent lamp 110 is defined.

The inverter 330 generates a discharge voltage for light emission of the flat fluorescent lamp 110.

The display unit 400 includes a liquid crystal panel 410 for displaying an image using light supplied from the flat fluorescent lamp 110 and a driving circuit unit 420 for driving the liquid crystal panel 410.

The liquid crystal panel 410 is interposed between a first substrate 412, a second substrate 414 coupled to the first substrate 412, and between the first substrate 412 and the second substrate 414. And a liquid crystal layer 416.

The first substrate 412 is a TFT substrate in which a thin film transistor (hereinafter, referred to as TFT) as a switching element is formed in a matrix form. In one example, the first substrate 412 is made of a glass material. A data line and a gate line are respectively connected to the source terminal and the gate terminal of the TFTs, and a pixel electrode made of a transparent conductive material is connected to the drain terminal.

The second substrate 414 is a color filter substrate in which RGB pixels for implementing colors are formed in a thin film form. For example, the second substrate 414 is made of glass. A common electrode made of a transparent conductive material is formed on the second substrate 414.

In the liquid crystal panel 410 having such a configuration, when power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. The arrangement of the liquid crystal molecules of the liquid crystal layer 416 interposed between the first substrate 412 and the second substrate 414 is changed by the electric field, and is supplied from the flat fluorescent lamp 110 according to the change in the arrangement of the liquid crystal molecules. The transmittance of light to be changed is displayed to display an image of a desired gray scale.

The driving circuit unit 420 may include a data printed circuit board 422 supplying a data driving signal to the liquid crystal panel 410, a gate printed circuit board 424 supplying a gate driving signal to the liquid crystal panel 410, and A data flexible printed circuit film 426 connecting the data printed circuit board 422 to the liquid crystal panel 410 and a gate flexible printed circuit film connecting the gate printed circuit board 424 to the liquid crystal panel 410. 428).

The data printed circuit board 422 is disposed on the side or the back of the storage container 310 by bending the data flexible printed circuit film 426, and the gate printed circuit board 424 is the gate flexible printed circuit. The bending of the film 428 is disposed on the side or back of the receiving container 310. The gate printed circuit board 424 may be removed by forming separate signal lines on the liquid crystal panel 410 and the gate flexible printed circuit film 428.

The liquid crystal display 500 further includes a first mold 340 disposed between the planar fluorescent lamp 110 and the first diffuser plate 130. The first mold 340 is coupled to the storage container 310 from the top of the flat fluorescent lamp 110 to fix the flat fluorescent lamp 110. The first mold 340 fixes the edges of the flat fluorescent lamp 110 while covering the external electrode region where light is not actually emitted, and the edges of the first and second diffuser plates 130 and 140 of the lens array shape. I support it. The first mold 340 may be integrally formed in a frame shape, may be formed of two pieces having a c or a "shape, or may be divided into four pieces corresponding to each side.

The liquid crystal display 500 further includes a first diffuser plate 130 having a lenticular lens pattern, a second diffuser plate 140 having a prism pattern, and a second mold 360.

The first and second diffusion plates 130 and 140 are disposed on the flat fluorescent lamp 110 and diffuse light emitted from the flat fluorescent lamp 110 to improve the uniformity of light. Since the first and second diffusion plates 130 and 140 have been described with reference to FIGS. 2 to 5, detailed description thereof will be omitted.

The first and second diffusion plates 130 and 140 may have a plate shape having a predetermined thickness, and may be spaced apart from the flat fluorescent lamp 110 at predetermined intervals. The first and second diffusion plates 130 and 140 are made of a transparent material to transmit light.

The second mold 360 is disposed between the second diffusion plate 140 and the liquid crystal panel 410. The second mold 360 fixes the edge of the second diffusion plate 140 and supports the edge of the liquid crystal panel 410. Like the first mold 340, the second mold 360 may be integrally formed in a frame shape or may have a structure divided into two or four pieces.

The liquid crystal display 500 may further include a buffer member 370 disposed between the storage container 410 and the flat fluorescent lamp 110 to support the flat fluorescent lamp 110. The buffer member 370 is disposed to correspond to an edge of the flat fluorescent lamp 110, and the flat fluorescent lamp 110 is spaced apart from the storage container 310 by a predetermined distance from the flat fluorescent lamp 110. Electrical contact between the metal storage container 310 is blocked. To this end, the buffer member 370 is made of an insulating material. In addition, the buffer member 370 is preferably made of a material having a certain degree of elasticity in order to absorb the impact applied from the outside. For example, the shock absorbing member 370 is made of silicon. The buffer member 370 is composed of two pieces having a c-shape. In contrast, the buffer member 370 is formed of four pieces corresponding to each side of the flat fluorescent lamp 110, or four pieces corresponding to four corners of the flat fluorescent lamp 110, Or it may be formed integrally of the frame shape.

The liquid crystal display 500 may further include a top chassis 380 for fixing the display unit 400. The top chassis 380 is coupled to the storage container 310 to fix the edge of the liquid crystal panel 410. In this case, the data printed circuit board 422 is bent by the data flexible printed circuit film 426 and fixed to the side or bottom of the storage container 410. The top chassis 380 is made of, for example, a metal having little deformation and excellent strength.

As described above, according to the present invention, the light provided from the flat fluorescent lamp is incident on the first diffuser plate having the lenticular lens pattern, and then diffused and scattered by the lenticular lens pattern. The diffused and scattered light is incident on the second diffuser plate having a prism pattern, and is then collected in a vertical direction by the prism pattern to be provided to the liquid crystal panel. Therefore, the front luminance increases, and the first and second diffusion plates serve as conventional optical sheets, thereby reducing the number of optical sheets required for the display device. Therefore, not only the manufacturing cost can be reduced, but also the thickness of the display device can be facilitated.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (9)

A lamp providing light; A first diffuser plate including a first flat plate base portion and a plurality of lenticular lens patterns protruding from a surface of the first flat plate base portion, the first diffuser plate disposed on the lamp to diffuse light provided from the lamp; And And a plurality of prism patterns having an angle of a vertex of 100 degrees or more and less than 180 degrees on the second flat plate base portion and the surface of the second flat plate base portion, and disposed on the first diffuser plate and emitted from the first diffuser plate. And a second diffuser plate for collecting light. The backlight assembly of claim 1, wherein the lenticular lens pattern has an inclination angle of 44 degrees to 46 degrees with respect to a surface of the first flat plate base portion, and a radius of curvature of 35 μm to 75 μm. The backlight assembly of claim 2, wherein the lenticular lens pattern is formed at a pitch of 100 μm to 200 μm. The backlight assembly of claim 1, wherein the second diffuser plate has a thickness of 0.5 mm ± 0.05 and transmittance is substantially 75% or more. The backlight assembly of claim 1, wherein the prism pattern has a pitch of about 100 μm to about 200 μm, and a vertex has a round shape. The backlight assembly of claim 5, wherein the radius of curvature of the round shape is 30 μm to 40 μm. A display panel which displays an image using light; And A lamp that provides light, a first diffusion plate that emits light emitted from the lamp by first diffusion, and a second diffusion plate disposed on the second diffusion plate to second diffuse and condense the first diffused light And a backlight assembly comprising a plate. The method of claim 7, wherein the first diffusion plate comprises a first flat plate base portion and a plurality of lenticular lens patterns protruding from the surface of the first flat plate base portion, Each of the lenticular lens patterns has an inclination angle of 44 degrees to 46 degrees with respect to a surface of the first flat plate base portion, and a radius of curvature of 35 μm to 75 μm. The display device of claim 7, wherein the second diffusion plate comprises a plurality of prism patterns each having a vertex angle of at least 100 degrees and less than 180 degrees on a surface of the second flat plate base portion and the second flat plate base portion.

Images