KR20040097426A - Liquid crystal display apparatus - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) is provided to improve a light efficiency and a brightness by installing a multiple-layered film having a function of polarizing and condensing the light under an LCD panel. CONSTITUTION: A light supply unit(210) is disposed under an LCD panel(100). An optical film(230) is disposed between the LCD panel and the light supplying unit. The optical film includes the first light condenser. A multiple-layered film(240) is disposed between the LCD panel and the optical film. The multiple-layered film has a polarizer and the second condenser. In case of the light supply unit(210) supplying a light, the light is condensed by the optical film. The condensed light is polarized by the polarizer and is condensed again by the second condenser, thereby having a high brightness.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY APPARATUS}

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device for improving display quality.

In general, a liquid crystal display includes a liquid crystal panel that displays an image using light and a backlight assembly that generates the light and provides the light to the liquid crystal panel.

The backlight assembly may include a lamp for generating the light, a light guide plate for changing the path of the light and outputting the light to the liquid crystal panel, optical sheets positioned on the light guide plate to equalize the brightness of the light, and leakage from the light guide plate. It includes a reflector for reflecting the light back to the light guide plate.

The optical sheets may include a first diffusion sheet for diffusing light incident from the light guide plate, a prism sheet positioned on the first diffusion sheet and condensing the light, and an optical diffusion sheet positioned on the prism sheet and diffusing the light. 2 diffusion sheets.

The prism sheet includes a first prism sheet for collecting the light in a first direction and a second prism sheet for collecting the light in a second direction different from the first direction in a horizontal direction.

Since the liquid crystal panel positioned on the backlight assembly uses only light partially polarized by the prism sheet and the diffusion sheet from the light emitted from the lamp, the efficiency of the light is low. In addition, when the light is incident on the prism sheet and the diffusion sheet, the light is scattered or absorbed at the incident surface of the prism sheet and the diffusion sheet to generate the light loss. As a result, the luminance of the liquid crystal panel is lowered and the display quality is lowered.

An object of the present invention is to provide a liquid crystal display device for improving display quality.

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

2A and 2B are diagrams simulating the luminance distribution of the liquid crystal panel according to the position of the multilayer film shown in FIG. 1.

3 is a cross-sectional view of the multilayer film shown in FIG. 1.

4A and 4B are cross-sectional views illustrating various examples of the polarizer illustrated in FIG. 3.

5A and 5B are cross-sectional views illustrating various examples of the light collecting units illustrated in FIG. 3.

6 is a cross-sectional view showing another example of the multilayer film shown in FIG. 1.

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

100: liquid crystal panel 200: backlight assembly

210: light supply portion 220: diffusion sheet

230: optical film 240: multilayer film

According to one aspect of the present invention, a liquid crystal display device includes a liquid crystal panel for displaying an image using liquid crystal, a light supply unit for generating the light, an optical film for primary condensing the light, and It consists of a multilayer film.

The light supply part provides first light passing through the liquid crystal. The optical film has a first condensing part that first condenses the first light and emits second light, and is positioned to face the liquid crystal panel between the liquid crystal panel and the light supply part. The multilayer film has a polarizing part that emits third light having increased brightness by polarizing the second light and a second condensing part which secondly condenses the third light and emits fourth light, wherein the optical film and the It is located between the liquid crystal panels.

According to such a liquid crystal display device, by providing the multilayer film for polarizing and condensing the light directly under the liquid crystal panel, the utilization rate of the light can be increased and the luminance can be improved.

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

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display device 300 according to the present invention is positioned below the liquid crystal panel 100 and the liquid crystal panel 100 for displaying an image using light, and generates the light. And a backlight assembly 200 for providing the liquid crystal panel 100.

In more detail, the liquid crystal panel 100 includes a first substrate 110 having a thin film transistor (TFT) formed in an array, and a second substrate coupled to face the first substrate 110. (120), the liquid crystal layer 130 formed between the first and second substrates 110 and 120, a spacer 140 for maintaining a cell gap, and a sealant for encapsulating the liquid crystal layer 130 ( 150).

The first substrate 110 includes a transparent glass substrate 111 and an active layer 112 having a TFT as a switching element formed on the transparent glass substrate 111.

The active layer 112 is a gate line for transmitting a gate signal, a data line for transmitting a data signal, and is connected to the gate line and the data line and is formed in a matrix form on the transparent glass substrate 111 so that the And a TFT for applying and blocking a signal voltage to the liquid crystal layer 130.

A source side tape carrier package (TCP) (not shown) for applying a data side driving signal to the data line is attached to the source side of the first substrate 110. A gate side TCP (not shown) for applying a gate side driving signal to the gate line is attached to the gate side of the first substrate 110.

The second substrate 120 provided on the first substrate 110 is formed on the transparent glass substrate 121 and the transparent glass substrate 121 and is expressed in a predetermined color by the light to display an image. And a color filter layer 122 for displaying.

The color filter layer 122 formed by the thin film process may be prepared by blocking a plurality of color pixels expressing a predetermined color and light leaked from the plurality of color pixels by using the light provided from the backlight assembly 200. It includes a black matrix to improve the ratio (C / R). In this case, the plurality of color pixels is generated by using a photoresist having a pigment or dye of red, green and blue colors.

In the liquid crystal layer 130 interposed between the first and second substrates 110 and 120, the alignment direction of liquid crystal molecules is continuously twisted by 90 ° with respect to the first and second substrates 110 and 120. Formed into twisted nematic liquid crystals.

The spacer 140 interposed between the first and second substrates 110 and 120 maintains a constant cell gap by separating the first substrate 110 and the second substrate 120 at predetermined intervals. do. In this case, the spacer 140 is positioned in the effective display area D of the first and second substrates 110 and 120 on which the image is displayed. The spacer 140 maintains a constant cell gap of the effective display area D to make the distribution of luminance uniform.

In general, the spacer 140 may be formed on the second substrate 120 because the TFT, the data, and the gate line included in the active layer 112 may be disconnected. As the spacer 140, a column spacer forming a pattern using a mask or a ball spacer having a ball shape may be used.

The sealant 150 interposed between the first and second substrates 110 and 120 is formed at the periphery of the effective display area D. The sealant 150 may form the liquid crystal layer 130 between the first and second substrates 110 and 120 by separating the first and second substrates 110 and 120 from each other at predetermined intervals. Space is secured.

Before forming the sealant 150, the first substrate 110 removes the active layer 112 in the seal line region where the sealant 150 is formed by an exposure process. At this time, the data line and the gate line of the active layer 112 are not removed to be electrically connected to the data side and the gate side TCP.

Meanwhile, the backlight assembly 200 provided below the liquid crystal panel 100 may include a light supply unit 210 for generating the light and a diffusion sheet 220 for diffusing the light incident from the light supply unit 210. ), An optical film 230 for condensing the light diffused by the diffusion sheet 220, and a multilayer film 240 for improving luminance.

The light supply unit 210 generates the light in response to a power supplied from the outside, and emits the light toward the liquid crystal panel 100.

The diffusion sheet 220 is provided on the light supply unit 210. The diffusion sheet 220 includes a plurality of transparent beads for scattering light to uniformly diffuse the light provided from the light supply unit 210 in all directions. Thus, the diffusion sheet 220 prevents the light from being biased in a specific region, thereby exhibiting a uniform luminance distribution.

The optical film 230 is provided on the diffusion sheet 220. The optical film 230 has a plurality of first light collecting portions having a prism shape formed on an upper surface thereof to condense the light incident from the diffusion sheet 220 in a first direction and to emit the light toward the liquid crystal panel 100.

The multilayer film 240 is interposed between the optical film 230 and the liquid crystal panel 100. The multilayer film 240 polarizes the light to improve luminance, and condenses the light in a second direction different from the first direction to provide the light to the liquid crystal panel 100. That is, the multilayer film 240 passes the first polarization component among the polarization components of the light, reflects the second polarization component different from the first polarization component, and changes the light into the light having the first polarization component to emit light. Increase the efficiency

As described above, the liquid crystal display device 300 according to the present invention polarizes and condenses the light using the multilayer film 240 without providing a polarizing plate. Accordingly, it is possible to reduce the light loss generated by passing through each sheet, and to reduce the cost.

In addition, the multilayer film 240 may be disposed directly below the liquid crystal panel 100 to increase the utilization rate of the light and to increase display quality.

2A and 2B are diagrams simulating the luminance distribution of the liquid crystal panel according to the position of the multilayer film shown in FIG. 1.

2A and 2B, the luminance distribution of the liquid crystal panel according to the position of the multilayer film 240 in the liquid crystal display device is shown using the 17 ″ liquid crystal display device as an example.

2A is a diagram illustrating the luminance of the liquid crystal panel 100 after the multilayer film 240 is disposed directly below the liquid crystal panel 100. That is, after the diffusion sheet 220, the optical film 230 and the multilayer film 240 are sequentially seated on the light supply unit 210, the liquid crystal panel 100 on the multilayer film 240. Place it. Looking at the luminance distribution in this structure, the maximum luminance value is 600.6 stilbe (stib, sb), the lowest luminance value is 4.1sb.

2B is a diagram illustrating the luminance of the liquid crystal panel 100 after the multilayer film 240 is interposed between the diffusion sheet 220 and the optical film 230. That is, the diffusion sheet 220, the multilayer film 240, and the optical film 230 are sequentially seated on the light supply unit 210, and then the liquid crystal panel 100 is disposed on the optical film 230. do. Looking at the luminance distribution in this structure, the maximum luminance value is 462.4sb, the lowest luminance value is 2.9sb.

Comparing the simulation results, the luminance is higher when the multilayer film 240 is positioned directly below the liquid crystal panel 100 to be in contact with the liquid crystal panel 100. That is, the optical film 230 is disposed between the multilayer film 240 and the liquid crystal panel 100 as compared with the maximum luminance value measured when the multilayer film 240 is disposed directly below the liquid crystal panel 100. ), The maximum luminance value when measured after the measurement is reduced by about 23%.

When the optical film 230 is positioned above the multilayer film 240, the light polarized by the multilayer film 240 passes through the optical film 230, thereby causing a change in polarization direction. Since the liquid crystal panel 100 is provided with the light having a different polarization direction by the optical film 230, the light efficiency is lowered, resulting in a result as shown in FIG. 2B. In addition, since the light is partially absorbed by the optical film 230, the amount of light provided to the liquid crystal panel 100 is lost.

On the other hand, when the multilayer film 240 is located directly below the liquid crystal panel 100, the liquid crystal panel 100 is located directly above the multilayer film 240 and thus enters the liquid crystal panel 100. There is no change in the polarization direction of the light. In addition, since the multilayer film 240 reflects the light having the second polarization component, which is a polarization component in a direction different from the polarization direction of the multilayer film 240, without reflecting the light, efficiency of the light is increased.

3 is a cross-sectional view of the multilayer film shown in FIG. 1.

Referring to FIG. 3, the multilayer film 240 includes a plurality of polarizers 241 for polarizing the light incident from the optical film 230 and a plurality of prisms formed on an upper surface of the polarizer 241. The second condenser 245 is included.

The polarizer 241 passes the first polarization component among the first and second polarization components of the light and reflects the second polarization component to increase the efficiency of the light.

The plurality of second light collecting units 245 formed on the upper surface of the polarizer 241 collect the light polarized by the polarizer 241 and provide the light to the liquid crystal panel 100. The plurality of second condensing parts 245 extend in a direction perpendicular to the plurality of first condensing parts.

Each of the second light collecting parts 50 forming the plurality of second light collecting parts 245 may have a first surface 51 and a first surface inclined in a third direction with respect to the upper surface of the polarizer 241. And a second surface 52 connected to 51 and inclined in a fourth direction different from the third direction with respect to the upper surface of the polarizer 241. That is, the first and second surfaces 51 and 52 are formed at a predetermined inclination angle from the upper surface of the polarizer 241.

The first and second surfaces 51 and 52 change the direction of the light incident from the polarizer 241 to direct the light and exit the light into the liquid crystal panel 100. At this time, it is preferable that the angle θ between the first surface 51 and the second surface 52 has 90 to 120 degrees.

4A and 4B are cross-sectional views illustrating various examples of the polarizer illustrated in FIG. 3.

Referring to FIG. 4A, the polarizer 241a includes a plurality of lower sheets 41 having birefringence and a plurality of upper sheets 42 having isorefractive.

In more detail, the plurality of lower sheets 41 are formed of polyethylene naphtalate having a high birefringence. The polyethylene naphthalate has a flat planar structure, and when laminated adjacent to each other, the lamination is good, and the refractive index in the stacking direction is significantly different from that in the other directions.

The upper second sheet 42 is formed of polymethyl methacrylate (PMMA) having an isotropic structure. The PMMA is an amorphous polymer and has an isotropic orientation, and thus the refractive index is the same in all directions.

The polarizer 241a has a multilayer film structure in which the plurality of lower sheets 41 and the plurality of upper sheets 42 are alternately stacked in hundreds of layers. That is, the second upper sheet 42a included in the plurality of upper sheets 42 is stacked on the upper surface of the first lower sheet 41a among the plurality of lower sheets 41, and the plurality of lower cities 41 are stacked. ), The second upper sheet 42b included in the plurality of upper sheets 42 is stacked on the upper surface of the second lower sheet 41b.

Since the refractive indexes of the plurality of lower sheets 41 and the plurality of upper sheets 42 are different from each other, the polarizer 241a passes the first polarization component of the light and reflects the second polarization component.

Referring to FIG. 4B, the polarizer 241b has a sheet shape, and includes a plurality of birefringent materials 45 to polarize and emit the light.

5A and 5B are cross-sectional views illustrating various examples of the plurality of second light collecting units illustrated in FIG. 3.

Referring to FIG. 5A, each of the second light collecting parts 70 forming the plurality of second light collecting parts 247 may be inclined in a third direction with respect to the upper surface of the polarizer 241. And a second surface 72 inclined in a fourth direction different from the third direction with respect to the upper surface of the polarizer 241 and a third surface 73 connected to the first and second surfaces 71 and 72. It includes. In this case, the first and second surfaces 71 and 72 have a predetermined inclination angle with respect to the upper surface of the polarizer 241.

The horizontal length L2 of the third surface 73 is formed to be smaller than the projection length L1 of the second light converging part 70. Therefore, the cross section of the second light collecting part 70 has a trapezoidal shape.

Referring to FIG. 5B, each of the second light collecting parts 80 forming the plurality of second light collecting parts 248 may be inclined in a third direction with respect to the top surface of the polarizer 241. And a second surface 82 inclined in a fourth direction different from the third direction with respect to the upper surface of the polarizer 241. In this case, the first and second surfaces 71 and 72 have a predetermined inclination angle with respect to the upper surface of the polarizer 241, and a point where the first surface 81 and the second surface 82 meet each other It is formed into a curved surface. The length L3 of the curved surface has a length of 10 to 20% with respect to the projection length L1. The radius of curvature R of the circle inscribed to the first and second surfaces 81, 82 and corresponding to the curved surface has a value of 20-50% with respect to the projection length L1.

6 is a cross-sectional view showing another example of the multilayer film shown in FIG. 1.

Referring to FIG. 6, the multilayer film 250 includes the polarizer 241 for polarizing the light incident from the optical film 230 and the plurality of prisms formed on an upper surface of the polarizer 241. A second condenser 245 and a protective sheet 251 for protecting the second condenser.

Since the plurality of second light collecting parts 245 have a prism shape, they protrude from the polarizer 241 to a predetermined height. Therefore, when the liquid crystal panel 100 or other sheets are seated on the plurality of second light collecting parts 245, the plurality of second light collecting parts 245 may be damaged by friction of the contact surface. In order to prevent such damage of the plurality of second light collecting parts 245, the protective sheet 251 is attached to the plurality of second light collecting parts 245. In this case, a diffusion sheet having a light transmittance of 85% or more is used as the protective sheet 251.

As described above, according to the present invention, by providing a multilayer film that polarizes light and then condenses the light, directly below the liquid crystal panel, the utilization of light can be increased, brightness can be improved, and display quality can be improved. .

In addition, since the multilayer film may serve as both a polarizer and a prism sheet, the number of optical sheets used in the liquid crystal display may be reduced, thereby reducing light loss due to the sheet. In addition, manufacturing costs can be reduced.

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

Claims (10)

A liquid crystal panel for displaying an image using liquid crystals; A light supply unit providing first light passing through the liquid crystal; An optical film having a first condenser configured to first condense the first light and emit a second light, the optical film being positioned to face the liquid crystal panel between the liquid crystal panel and the light supply part; A polarizing part emitting polarized light by emitting the third light having increased brightness by polarizing the second light, and a second condensing part emitting second light by condensing the third light and emitting fourth light, wherein the optical film and the liquid crystal panel Liquid crystal display device comprising a multilayer film positioned between The method of claim 1, wherein the polarizing portion has a plurality of first layers having birefringence and a plurality of second layers having isorefractive properties, and the plurality of first and second layers are alternately stacked. LCD display device. The liquid crystal display of claim 1, wherein the polarizer comprises a plurality of birefringent materials. The liquid crystal display of claim 1, wherein the second condenser is formed in a direction orthogonal to the first condenser. The light emitting device of claim 1, wherein the second light converging part is a first surface inclined with respect to the polarizing part; And a second surface inclined with respect to the polarizer to meet the first surface, wherein an angle between the first surface and the second surface is 90 degrees to 120 degrees. 6. The liquid crystal display device according to claim 5, wherein the edge where the first surface and the second surface of the second light collecting portion meet each other is formed as a curved portion to improve front luminance. 7. The liquid crystal display device according to claim 6, wherein the length of the curved portion has a length of 10 to 20% of the projection length of the second condensing portion. The method of claim 1, wherein the second light collecting unit, A first surface inclined with respect to the polarizer; A second surface inclined with respect to the polarizer to meet the first surface; And And a third surface connected to the first and second surfaces and facing the polarizer, wherein an angle between the first surface and the second surface is 90 degrees to 120 degrees. The liquid crystal display device according to claim 1, further comprising a protective sheet interposed between the multilayer film and the liquid crystal panel to protect the second light collecting part. The liquid crystal display device according to claim 1, further comprising a diffusion sheet interposed between the light supply unit and the optical film to diffuse the first light to emit the fifth light.