KR20070010408A - Liquid crystal display - Google Patents

Abstract

An LCD is provided to improve brightness and reduce a manufacturing cost by using a plurality of diffusion sheets. A liquid crystal panel displays an image. A light source(320) is disposed at the back of the liquid crystal panel, and supplies light to the liquid crystal panel. A diffusion sheet layer is disposed between the liquid crystal panel and the light source, and includes at least one first diffusion sheet having a surface facing the liquid crystal panel and including a diffusion agent layer(354), and a second diffusion sheet disposed at the back of the first diffusion sheet including an adhesion preventing layer(355) at a surface facing the diffusion agent layer provided at a surface facing the liquid crystal panel and the light source. The adhesion preventing layer has a thickness of about 1 m to 10 m.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

1 is an exploded perspective view of a liquid crystal display according to a first embodiment of the present invention;

2 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention;

3 is a cross-sectional view of a liquid crystal display device according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: liquid crystal panel 160: mold frame

300: backlight unit 310: light guide plate

320: light source 340: reflective sheet

350: diffusion sheet layer 353: diffusion sheet layer body

354: diffusing agent layer 355: adhesion prevention layer

351: first diffusion sheet 352: second diffusion sheet

356: transparent plate 360: prism sheet layer

370 reflective polarizing film

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device using a plurality of diffusion sheets.

The liquid crystal display device includes a liquid crystal layer in which liquid crystal is injected between the thin film transistor substrate and the color filter substrate. In addition, since the liquid crystal display is a non-light emitting device, a backlight unit for supplying light is disposed on the rear surface of the thin film transistor substrate. Light transmitted from the light source of the backlight unit is adjusted according to the arrangement of the liquid crystal.

The backlight unit is divided into a direct type and an edge type according to the position of the light source. The edge type is a structure in which a light source is installed on the side of the light guide plate, and is mainly applied to a relatively small liquid crystal display device such as a laptop type and a desktop computer. Such an edge type backlight unit has a good light uniformity, a long service life, and is advantageous for thinning a liquid crystal display device.

The direct type is a structure mainly developed as the size of the liquid crystal display device is enlarged. The structure directly irradiates light to the liquid crystal panel by arranging one or more light sources in a row on the lower surface of the liquid crystal panel. Such a direct type backlight unit has a merit that it is possible to use a plurality of light sources as compared to an edge type backlight unit to secure a high brightness, but has a disadvantage of uneven brightness when thinned.

In order to compensate for the disadvantages of the direct type backlight unit, a diffusion sheet layer may be disposed between the liquid crystal panel and the light source to evenly distribute light from the backlight unit to the liquid crystal panel.

A diffuser layer formed by applying a bead-shaped diffuser is provided on a surface facing the liquid crystal panel of the diffusion sheet, and an adhesion preventing layer is formed on the surface facing the light source to prevent adhesion to the underlying structure. As such, since two or more diffusion sheets, each of which is composed of several layers, are laminated and used, there is a problem in that light intensity decreases toward the upper side and the thickness of the entire diffusion sheet layer becomes thick.

Accordingly, an object of the present invention is to provide a liquid crystal display device which can improve the brightness and reduce the cost.

The object is, according to the present invention, a liquid crystal panel for displaying a screen; A light source disposed at a rear of the liquid crystal panel to supply light to the liquid crystal panel; At least one first diffusion sheet disposed between the liquid crystal panel and the light source and provided with a diffusion layer on a surface facing the liquid crystal panel; A liquid crystal display device including a diffusion sheet layer disposed behind the first diffusion sheet and having a second diffusion sheet including the diffusion layer disposed on a surface facing the liquid crystal panel and the adhesion preventing layer provided on the surface facing the light source. Is achieved by.

The adhesion preventing layer is preferably formed to a thickness of about 1㎛ ~ 10㎛.

It is preferable that the transparent plate disposed between the diffusion sheet layer and the light source is made of an acrylic material and further includes a diffusion agent therein.

A plurality of light sources may be provided over the entire rear surface of the transparent plate.

It may further include a prism sheet layer provided between the liquid crystal panel and the diffusion sheet layer, it is preferable that the adhesion preventing layer is provided on the rear surface of the prism sheet layer.

It may further include a reflective polarizing film provided between the liquid crystal panel and the diffusion sheet layer, it is preferable that the adhesion preventing layer is provided on the back of the reflective polarizing pen.

The light guide plate may further include a light guide plate disposed between the diffusion sheet layer and the light source, and the light source may be provided along at least one side of the light guide plate.

The light source may include a lamp or an LED, and a cold cathode fluorescent lamp or an external electrode fluorescent lamp is generally used as the lamp.

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

Prior to the description, in the various embodiments, components having the same configuration will be representatively described in the first embodiment using the same reference numerals, and in other embodiments, only the configuration different from the first embodiment will be described. do.

A liquid crystal display according to a first exemplary embodiment of the present invention will be described with reference to FIGS. 1 and 2 as follows.

The liquid crystal display device 1 includes a liquid crystal panel 100 and a backlight unit 300.

The liquid crystal panel 100 bonds the thin film transistor substrate 101 on which the thin film transistor 101 is formed, the color filter substrate 102 and the two substrates 101 and 102 facing the thin film transistor substrate 101 to form a cell gap. a sealant forming a cell gap, and a liquid crystal layer positioned between both substrates 101 and 102 and the sealant. The liquid crystal panel 100 forms a screen by adjusting the arrangement of the liquid crystal layer, but because it is a non-light emitting device, light must be supplied from the light source 320 located on the rear surface.

One side of the thin film transistor substrate 101 is provided with a driver for applying a driving signal. The driving unit includes a flexible printed circuit board (FPC. 145), a driving chip 143 mounted on the flexible printed circuit board 145, and a circuit board (PCB, 140) connected to the other side of the flexible printed circuit board 145. Include. The illustrated driving unit represents a chip on film (COF) method, and other known methods such as a tape carrier package (TCP) and a chip on glass (COG) are possible. In addition, the driver may be formed on the thin film transistor substrate 101 during the wiring formation process.

 The backlight unit 300 disposed on the rear surface of the liquid crystal panel 100 is disposed on the rear surface of the optical sheet and arranged in parallel to each other to emit light, and the reflection located on the rear surface of the light source 320. The sheet 340 includes a mold frame 160 supporting the liquid crystal panel 100 and optical sheets. The optical sheet includes a reflective polarizing film 370, a prism sheet layer 360, and a diffusion sheet layer 350 positioned on the rear surface of the liquid crystal panel 100.

The light source 320 is arranged in parallel to the rear of the optical sheet and the cold cathode fluorescent lamp (CCFL; Cold Cathode Flourscent Lamp) is used as the light source 320, but a hot cathode fluorescent lamp or an external electrode fluorescent lamp (EEFL) Various lamps such as Electrode Flourscent Lamp may be used.

The diffusion sheet layer 350 includes a first diffusion sheet 351 and a second diffusion sheet, and the first diffusion sheet 351 is a diffusion sheet layer body 353 composed of polymethylmethacrylate and polycarbonate, which are light transmissive resins. ) And a diffuser layer 354 formed by applying a bead-shaped diffuser to a surface of the diffusion sheet layer body 353 facing the liquid crystal panel.

The light emitted from the light source 320 is uniformly diffused while passing through the first diffusion sheet 351 to provide uniform light to the liquid crystal panel 100, thereby contributing to the improvement of luminance. Therefore, in order to increase this effect, the first diffusion sheet 351 is used by stacking several sheets.

On the back of the first diffusion sheet 351, the diffusion sheet layer body 353 and the diffusion sheet layer body 353 of the diffusion sheet layer body 353 facing the liquid crystal panel 100 are provided. The second diffusion sheet 352 including the adhesion preventing layer 355 provided on the surface facing the light source 320 is disposed. The adhesion preventing layer 355 protects the transparent plate 356 supporting the diffusion sheet layer 350, serves to prevent foreign material adsorption by static electricity, and has a thickness of 3 μm to 10 μm. The back of the second diffusion sheet 352 is provided with a transparent plate 356, the material is made of an acrylic material, and includes a diffusing agent therein. The transparent plate 356 supports the diffusion sheet layer 350 at the same time and serves to diffuse the light evenly.

Conventionally, a plurality of diffusion sheets including both the diffusion agent layer 354 and the adhesion preventing layer 355 are laminated without using the first diffusion sheet 351 and the second diffusion sheet 352, but the diffusion sheet layer 350 may be used. As the thickness becomes thicker, there is a problem in that the intensity of light directed toward the liquid crystal panel 100 is weakened. In order to solve this problem, in the present invention, the upper and lower surfaces of the plurality of first diffusion sheets 351 and the diffusion sheet layer body 353 in which the diffusion agent layer 354 is provided only on the surface of the diffusion sheet layer body 353 facing the liquid crystal panel. The diffusion sheet layer 350 in which a single number of second diffusion sheets 352 having both the diffusion agent layer 354 and the adhesion preventing layer 355 are laminated is used.

As such, by using the diffusion sheet layer 350 according to the present invention, as the thickness of the diffusion sheet layer 350 increases, the light intensity directed to the liquid crystal panel decreases.

In addition, the transparent plate may be formed by the adhesion preventing layer 355 formed on the surface of the second diffusion sheet 352 facing the light source 320 and positioned at the bottom of the diffusion sheet layer 350 to be in contact with the transparent plate 356. 356) foreign matter adsorption, moisture infiltration and moiré phenomenon is reduced. Moiré phenomenon refers to the noise of the wave pattern appearing on the screen by the light emitted from the light source 320 interferes with the pixels of the liquid crystal panel 100.

The prism sheet layer 360 is provided between the liquid crystal panel 100 and the diffusion sheet layer 350.

The prism sheet layer 360 has a triangular prism-shaped prism formed on a surface facing the liquid crystal panel 100, and the light diffused from the diffusion sheet layer 350 is perpendicular to the plane of the upper liquid crystal panel 100. At least two prism sheets are typically stacked and used to serve to condense in one direction and for uniform luminance distribution.

At this time, by forming the adhesion preventing layer 355 on the lower surface of the prism sheet layer 360, it is possible to reduce problems such as moisture penetration due to contact with the diffusion sheet layer 350, foreign matter adsorption by static electricity.

The reflective polarizing film 370 positioned on the prism sheet layer 360 is adjusted to have high luminance by performing repeated polarization transmission and reflection processes on the light collected from the prism sheet layer 360. Like the prism sheet layer 360, the adhesion preventing layer 355 may be formed on the surface of the reflective polarizing film 370 facing the light source 320, but may be omitted because it is not an essential component in the present invention.

The reflective sheet 340 disposed on the rear surface of the light source 320 reflects the light of the light source 320 and supplies the light toward the diffusion sheet layer 350. The reflective sheet 340 may be made of polyethylene terephthalate (PET) or polycarbonate (PC). The reflective sheet 340 reflects the light transmitted in the opposite direction of the liquid crystal panel 100 back toward the liquid crystal panel 100, thereby reducing the loss of light and improving the uniformity of the light transmitted in the liquid crystal panel 100 direction. Will contribute.

Typically, the backlight unit 300 and the mold frame 160 are accommodated by the lower chassis and the lower chassis may be combined with the upper chassis 150 but may not be used. The upper chassis 150 has a display window so that the display area of the liquid crystal panel 100 is exposed to the outside.

Hereinafter, the liquid crystal display device 1 according to the second embodiment of the present invention will be described with reference to FIG. 3. The second embodiment is an invention of the liquid crystal display device 1 having an edge type light source 320 structure, and the same description as that of the first embodiment is omitted in the overall configuration, and the arrangement and part of the light source 320 are omitted. I will explain mainly.

In the first exemplary embodiment, a light guide plate 310 made of polymethylmethacrylate (PMMA) having high strength and high transmittance is provided on the rear surface of the diffusion sheet layer 350 in which the transparent plate 356 is provided. . In general, the light guide plate 310 may be provided in a wedge type in which the bottom surface is inclined and the top surface is flat, or in a plate type in which both the bottom surface and the top surface are flat.

Here, the light source 320 is disposed up and down at least one along the edge of the light guide plate, and guides the light generated from the light source 320 to the rear surface of the liquid crystal panel 100.

In this case, the diffusion sheet layer 350 is used to evenly diffuse light in the light guide plate 310 to guide the back of the liquid crystal panel 100. The diffusion sheet layer 350 is positioned on the back surface of the plurality of first diffusion sheets 351 and the first diffusion sheet 351 having the diffusion agent layer 354 on the surface of the diffusion sheet layer body 353 facing the liquid crystal panel. A second diffusion sheet 352 is included. The second diffusion sheet 352 has a diffusion agent layer 354 on the surface of the diffusion sheet layer body 353 facing the liquid crystal panel 100 and a adhesion preventing layer having a thickness of 3 μm to 10 μm on the surface facing the light source 320 ( 355).

The second diffusion sheet 352 having the adhesion preventing layer 355 to prevent contact between the first diffusion sheet 351 from which the unnecessary adhesion preventing layer 355 is removed and the lower structure such as the diffusion plate 356 or the light guide plate 310. By uniformly dispersing the light is directed toward the liquid crystal panel 100 and at the same time cost reduction effect.

Although some embodiments of the invention have been shown and described, those skilled in the art will appreciate the structure of the diffusion sheet in stacking a plurality of diffusion sheets without departing from the principles or spirit of the invention. It will be appreciated that the present embodiment can be modified with the modification. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, a liquid crystal display device having reduced cost and improved luminance by changing the structure of the diffusion sheet layer is provided.

Claims (11)

A liquid crystal panel displaying a screen; A light source disposed at a rear of the liquid crystal panel to supply light to the liquid crystal panel; At least one first diffusion sheet disposed between the liquid crystal panel and the light source and having a diffusion layer disposed on a surface facing the liquid crystal panel, and disposed at a rear surface of the first diffusion sheet and facing the liquid crystal panel. And a diffusion sheet layer having a diffusion sheet and a second diffusion sheet including an adhesion preventing layer provided on a surface facing the light source. The method of claim 1 The adhesion preventing layer is formed of a liquid crystal display device having a thickness of about 1 ㎛ ~ 10 ㎛. The method of claim 1 Further comprising a transparent plate disposed between the diffusion sheet layer and the light source, And a plurality of light sources are provided over the entire rear surface of the transparent plate. The method of claim 2, The transparent plate is made of an acrylic material, characterized in that it further comprises a diffusing agent therein. The method of claim 1, And a prism sheet between the liquid crystal panel and the diffusion sheet layer. The method of claim 4, wherein And the adhesion preventing layer is formed on a rear surface of the prism sheet. The method of claim 1, And a reflective polarizing film provided between the liquid crystal panel and the diffusion sheet layer. The method of claim 6, And the adhesion preventing layer is formed on a rear surface of the reflective polarizing film. The method of claim 1 Further comprising a light guide plate disposed between the diffusion sheet layer and the light source, The light source is a liquid crystal display, characterized in that provided along at least one side of the light guide plate. The method of claim 1, The light source includes a cold cathode fluorescent lamp. The method of claim 1, And the light source comprises an LED.

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