KR20080023503A - Liquid crystal display device including optical film and optical film - Google Patents

Abstract

A light functional film and an LCD comprising the same are provided to induce total reflection of light, which is generated from a backlight assembly, through the light functional film, thereby increasing the contrast ratio of a visual field. An LCD comprises a backlight assembly, an LCD panel disposed above the backlight assembly, and a light functional film(100). The light functional film includes a transparent sheet(110) disposed on the LCD panel, a reflection pattern(120) formed in the transparent sheet, and an external light-absorbing part(130) formed within the reflection pattern. The reflection pattern induces total reflection of light passing through the LCD panel.

Description

Liquid crystal display device and optical functional film including optical functional film {LIQUID CRYSTAL DISPLAY DEVICE INCLUDING OPTICAL FILM AND OPTICAL FILM}

1 is an exploded perspective view schematically showing a liquid crystal display device according to an embodiment of the present invention.

Figure 2 is a cross-sectional view of the optical functional film for explaining the optical functional film according to an embodiment of the present invention.

3 is a perspective view of the photofunctional film of FIG. 2.

4 to 6 are cross-sectional views of optical functional films for explaining various shapes of the external light absorbing unit.

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

10: backlight assembly 12: optical sheet

13: Diffusion sheet 14: Prism sheet

15: Protection sheet 16: Light source part

17 ： reflective sheeting 20 ： liquid crystal display panel

21: Liquid crystal panel 25: Drive part

41: lower cover 42: upper cover

100: photofunctional film

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and an optical functional film capable of improving contrast ratio.

As the modern society becomes more and more information, photoelectronics related parts and devices are remarkably advanced and spread. Among them, display apparatuses for displaying images are widely used for television apparatuses, monitor apparatuses for personal computers, and the like, and thinning is progressing at the same time as these displays are enlarged.

Recently, a flat panel display such as a liquid crystal display device, a plasma display panel (PDP), and an organic light emitting diode (OLED) has been developed in place of the conventional CRT. Among them, the liquid crystal display device has a lower operating voltage than the CRT representing a conventional display device, which consumes less power, can be used in terms of weight and volume, and can be thinner. Be in the spotlight.

The liquid crystal display device includes a thin film transistor substrate, a color filter substrate, and a liquid crystal panel in which a liquid crystal layer is positioned between both substrates. Here, since the liquid crystal panel is a non-light emitting device, the backlight unit may be positioned on the rear surface of the liquid crystal panel.

Looking at the liquid crystal layer positioned between both substrates of the liquid crystal display device, the position is changed by the electric field applied to both substrates, and the amount of light passing through is changed, and a color filter can be used to express color. Typically, the pixel unit of the filter consists of three subpixels: red, green, and blue.

Although remarkably developed, there is a problem in that the display power of the image is also degraded due to color deviation in the liquid crystal display device. Even the surface of the liquid crystal display device is affected by the reflection of external light, and the problem that the color purity does not reach the cathode ray tube is not completely solved.

In such a liquid crystal display device according to the prior art, the superposition of the incident light generated in the backlight and the external ambient light occurs in the bright external conditions. As a result, the contrast ratio is lowered in the bright room condition, and the screen display capability of the liquid crystal display device is poor.

The present invention is to overcome the above problems, an object of the present invention to provide a liquid crystal display device that can reduce the effect of color deviation in the image represented by the liquid crystal display device.

Another object of the present invention is to provide a liquid crystal display device which can improve the contrast even under the condition of bright external light, and can prevent the adverse effect of light reflection on the surface.

The liquid crystal display device according to the present invention includes a backlight assembly, a liquid crystal display panel and a photofunctional film.

Since the liquid crystal display panel of the liquid crystal display device is made of a non-light emitting device that does not emit light unlike the plasma display panel (PDP) device, a backlight assembly must be provided on the back of the liquid crystal display panel. Specifically, the liquid crystal display panel includes a liquid crystal panel for forming an image and a driver for driving the liquid crystal panel. The backlight assembly may include a light source unit for irradiating light to the rear surface of the liquid crystal panel, and in addition to the light source unit, the backlight assembly may be coupled to a mold frame for supporting the side of the liquid crystal panel, a lower cover for receiving the light source unit, and a lower cover. It may include a top cover to cover the front of the.

The photofunctional film includes a transparent sheet, a reflective pattern, and an external light absorbing portion. First, the transparent sheet may be formed of a transparent material through which light emitted from the backlight assembly may pass. The reflective pattern may be irradiated from the backlight assembly to induce total reflection of light passing through the liquid crystal display panel. Light is totally reflected by the reflection pattern, and the light mixing is further improved by the total reflection to reduce color deviation. The external light absorbing part may be provided inside the reflective pattern to absorb external external ambient light.

The reflective pattern may have a cross section in a wedge shape or a trapezoidal shape in the inside of the transparent sheet, and in addition, may have a cross section of various shapes. In addition, the reflective pattern may be provided in a stripe pattern having a predetermined interval at the front or the back of the transparent sheet, but in some cases may be provided in a two-dimensionally arranged dot or a specific pattern pattern. In addition, the reflective pattern may be provided in a thin line or granular shape in the transparent sheet.

If the reflective pattern is provided in a wedge or trapezoidal shape, the side slope may be inclined at 0 degrees to 45 degrees, and may preferably have a slope of 1 degree to 5 degrees. An inclination may be formed on the side of the reflective pattern to increase the diffusion angle of light emitted from the liquid crystal panel. In this case, the reflective pattern may be variously formed in a stripe or wave shape.

The external light absorbing part provided inside the reflective pattern is formed of a light absorbing material, and preferably may fill black carbon.

However, the refractive index of the external light absorbing portion should be smaller than the refractive index of the transparent sheet so that light transmitted through the transparent sheet and reflected on the reflective pattern is totally reflected.

Hereinafter, a liquid crystal display device according to embodiments of the present invention will be described with reference to the accompanying drawings.

1 is an exploded perspective view schematically showing a liquid crystal display device according to an embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display device 1 according to the exemplary embodiment includes a backlight assembly 10, a liquid crystal display panel 20, and a photofunctional film 100.

First, since the liquid crystal display panel 20 is a non-light emitting device that does not emit light unlike the PDP device, the backlight assembly 10 is provided on the rear surface of the liquid crystal display panel 20. Specifically, the liquid crystal display panel 20 includes a liquid crystal panel 21 for forming an image and a driver 25 for driving the liquid crystal panel 21.

In addition, the backlight assembly 10 includes a backlight unit 11 for irradiating light to the rear surface of the liquid crystal panel 21. In the liquid crystal display device according to the present embodiment, in addition to the liquid crystal display panel 20, the backlight assembly 10, and the optical functional element 100, the mold frame 31 and the backlight unit 11 supporting the side portions of the liquid crystal panel 32 are provided. The upper cover 42 may be coupled to the lower cover 41 and the lower cover 41 to accommodate the upper cover 42 to cover the front surface of the liquid crystal panel 21.

Since the liquid crystal display device cannot emit light by itself, an external light source is required for light emission. In general, a liquid crystal display device provides a light by mounting a backlight unit on the back of the liquid crystal panel. Light sources used in the backlight unit include a Cold Cathode Fluorescent Lamp (CCFL), a Flat Fluorescent Lamp (FFL), and a Light Emitting Diode (LED).

The liquid crystal panel 21 is injected between the thin film transistor substrate 22, the color filter substrate 23 attached to face the thin film transistor substrate 22, and the thin film transistor substrate 22 and the color filter substrate 23. It includes a liquid crystal (not shown). The liquid crystal (not shown) is injected between the thin film transistor substrate 22 and the color filter substrate 23 and then sealed. The liquid crystal panel 21 is arranged in a matrix form of the liquid crystal cells forming a pixel unit, and forms an image by adjusting the light transmittance of the liquid crystal cells according to the image signal information transmitted from the driver 25.

A plurality of gate lines and a plurality of data lines are formed in a matrix form on the thin film transistor substrate 22, and a pixel electrode and a thin film transistor (TFT) are formed at the intersection of the gate lines and the data lines. The signal voltage applied through the thin film transistor is applied to the liquid crystal (not shown) by the pixel electrode, and the liquid crystal (not shown) is aligned according to the signal voltage to determine the light transmittance.

The color filter substrate 23 is formed with a color filter made of RGB pixels through which light passes and a common electrode made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). . The color filter substrate 23 has a smaller area than the thin film transistor substrate 22, and a portion where the color filter substrate 23 and the thin film transistor substrate 22 overlap with each other becomes a display area of the liquid crystal panel 21 and does not overlap. The peripheral area of the display area becomes the non-display area of the liquid crystal panel. One side of the thin film transistor substrate 22 is provided with a driver 25 for applying a drive signal.

The driver 25 includes a flexible printed circuit board (FPC) 26, a driving chip 27 mounted on the flexible printed circuit board 26, and a circuit board connected to the other side of the flexible printed circuit board 26. 28). The driver 25 shown illustrates a method of a chip on film (COF), and other known methods such as a taper carrier package (TCP) and a chip on glass (COG) may be used. In addition, the driver 25 may be mounted on the thin film transistor substrate 22.

The mold frame 31 is formed along the side of the liquid crystal panel 21, has a substantially rectangular shape, and supports the liquid crystal panel 21 spaced apart from the backlight unit 11.

The backlight unit 11 has a direct type and an edge type, is located on the rear surface of the liquid crystal panel 21, and includes an optical sheet 12, a light source unit 16, and a reflective sheet 17.

The optical sheets 12 are positioned on the rear surface of the liquid crystal panel 21 and include a diffusion sheet 13, a prism sheet 14, and a protective sheet 15. Here, the diffusion sheet 13 consists of a base plate and a bead-shaped coating layer formed on the base plate. The diffusion sheet 13 serves to diffuse the light from the light source unit 16 and supply the light to the liquid crystal panel 21. The diffusion sheet 13 may be used by overlapping two or three sheets. Since the diffusion sheet 13 is not supported by the light guide plate, unlike the edge type, the diffusion sheet 13 may be somewhat thicker for strength. The prism sheet 14 is formed with a triangular prism-like prism on an upper surface thereof. The prism sheet 14 collects light diffused from the diffusion sheet 13 in a direction perpendicular to the plane of the upper liquid crystal panel 21. Two prism sheets 14 are usually used, and the micro prisms formed on each prism sheet 14 are at an angle. The light passing through the prism sheet 14 proceeds almost vertically to provide a uniform luminance distribution. The uppermost protective sheet 15 protects the prism sheet 14 that is weak to scratches. The light source part 16 which irradiates light to the back surface of the liquid crystal panel 21 is arrange | positioned at the back surface of the prism sheet 14.

In addition, the optical functional film 100 is provided on the color filter substrate 23 on the liquid crystal display panel 20. Hereinafter, the optical functional film will be described in detail.

Figure 2 is a cross-sectional view of the optical functional film for explaining the optical functional film according to an embodiment of the present invention.

2, the optical functional film 100 according to an embodiment of the present invention includes a transparent sheet 110, a reflective pattern 120, and an external light absorbing unit 130.

The transparent sheet 110 may be formed of a light transmissive material through which light emitted from the backlight unit may pass. For example, the transparent sheet 110 may be formed of an ultraviolet curable resin.

The reflective pattern 120 may induce total reflection of light that is irradiated from the backlight unit and passes through the liquid crystal display panel. In this embodiment, the reflective pattern 120 is a boundary surface of the external light absorbing unit 130.

In addition, the external light absorbing part 130 may be provided inside the reflective pattern 120 to absorb external external light 210.

In addition, although not described in the present embodiment, in some cases, the reflective pattern and the transparent sheet can be protected, and the base is formed on the surface of the transparent sheet to increase the impact resistance of the liquid crystal display device and to facilitate the manufacturing process of the optical functional film. The film may be further provided, wherein the base film may be formed using a transparent material.

The external light absorbing unit 130 may be formed of a black organic material, an inorganic material, or a metal that can absorb light. In addition, as the external light absorbing unit 130, an ultraviolet curable resin containing carbon may be used.

The external light absorbing portion of the present invention may be formed by a roll molding method, a heat press method using a thermoplastic resin, or an injection molding method for filling a thermoplastic or thermosetting resin into a transparent sheet transferred to a shape opposite to the external light absorbing portion. have.

The external light absorbing part may use metal powder such as black, organic material, inorganic material, or copper oxide such as carbon black, black ink, black pigment, etc., and blend the black ink in which black powder is well dispersed into transparent resin having a controlled refractive index. Then, the patterned transparent sheet is poured and filled with the light absorbing material in the space with the pattern, and then the remaining portion is removed using a doctor blade or the like. In order to remove the external light absorbing material left on the transparent sheet, a release agent or the like may be added to the transparent resin.

The external light absorbing unit 130 constituting the optical functional sheet 100 absorbs the external environmental light 210 to prevent the external environmental light 320 from flowing into the transparent sheet, and substantially borders the external light absorbing unit 130. The reflective pattern 120 may induce incident light 220 from the backlight assembly toward the viewer through total reflection, and may reduce color deviation through mixing of RGB light. Thus, a high transmittance to visible light and a high contrast ratio can be obtained.

3 is a perspective view of the photofunctional film of FIG. 2.

Referring to FIG. 3, the cross-section of the reflective pattern in the inside of the transparent sheet has a wedge shape and is provided in a stripe shape. However, in some cases, the cross section of the reflective pattern may have a trapezoidal cross section in addition to the wedge shape inside the transparent sheet.

When the reflection pattern is provided in a wedge or trapezoidal shape, the side slope of the reflection pattern may be inclined at 0 degrees to 45 degrees, and the inclination may be formed to increase the diffusion angle of light emitted from the liquid crystal panel. In addition, by having an inclination of 1 degree to 5 degrees, an optimal total reflection effect can be obtained.

The external light absorbing part provided inside the reflective pattern is formed of a material absorbing light, and may be formed by filling black carbon. However, the refractive index of the external light absorbing portion should be smaller than the refractive index of the transparent sheet so that the light irradiated to the reflective pattern through the transparent sheet is totally reflected.

In addition, although the reflective pattern is provided in a stripe shape in this embodiment, it may be variously formed in a wave shape in some cases.

In addition, although the bottom surface of the wedge may be provided in the direction in which incident light flows in the reflective pattern 120 as shown in FIG. 3, as shown in FIG. 4, the bottom surface of the wedge is external ambient light as shown in FIG. 4. It may be formed in the inflow direction. Of course, the reflective pattern is formed inwardly from the surface of the transparent sheet in one embodiment of the present invention, but in some cases it may be formed entirely inside.

In addition, the reflective pattern 120-2 may be provided to have a trapezoidal cross section as shown in FIG. 5, and the reflective pattern 120-3 may also be provided in the transparent sheet in a granular shape as shown in FIG. 6. It may be.

In addition, the liquid crystal display device according to the present invention may further be provided with a glass sheet on the upper surface of the optical functional film in order to supplement the strength of the optical functional film. And, according to the intention of the manufacturer may further provide an antireflection film on the upper surface of the glass sheet. Specifically, the anti-reflection film is an AR / LR film, AR (Anti Reflective) film is mainly attached to the PDP (Plasma Display Panel) optical filter can prevent the surface reflection or glare of the screen. That is, the reflected light is reduced by stacking films having different refractive indices and utilizing optical interference. On the other hand, LR (Low Reflective) film is a film having a reflectance of 1% by applying a low refractive index material.

Table 1 is a comparison table showing the color deviation before and after using the optical functional film according to the present invention in the liquid crystal display device, Table 2 shows the difference in reflectance before and after using the optical functional film according to the present invention in the liquid crystal display device The comparison table shown.

Table 1

[Table 2]

Referring to Table 1, when a color deviation occurs depending on the viewing angle of the liquid crystal display device according to the viewing angle, each viewer sees a different color and eventually results in viewing a different image. It is advantageous that the deviation is small. For example, in Table 1, Δx30 represents the difference between the color coordinates x at the front and the 30 degree viewing angle, and specifically, when the optical functional film according to the present invention is employed, the color when viewed from the Δx30, that is, the 30 degree viewing angle relative to the center. The deviation value is 0.0074, and after adopting the optical functional film according to the present invention, it can be seen that the value of the color deviation is significantly reduced to 0.0055 when viewed at Δx30, that is, at a 30 degree viewing angle from the center.

In addition, referring to Table 2, the reflectance and scattering rate of the liquid crystal display device before using the optical functional film according to the present invention are 5.38% and 1.38%, respectively, and the values are more pronounced compared to the reflectance and scattering ratio of the optical functional film after use. You can see the big thing.

Therefore, in the liquid crystal display device to which the optical functional film according to the present invention is applied, the value of the color deviation is reduced, so that even when viewed from various angles, a relatively identical color can be provided, and the reflectance and scattering rate are reduced to provide a clear image and high color clarity. Can be.

The liquid crystal display device according to the present invention has an effect of reducing the influence of color deviation in the image represented by the liquid crystal display device.

In addition, the liquid crystal display device according to the present invention can be irradiated to the outside by the total reflection of the light generated from the backlight assembly using the optical functional film having a reflective pattern has the effect of increasing the contrast ratio of the field of view.

In addition, the liquid crystal display device according to the present invention includes an external light absorbing portion inside the reflective pattern, so that external environmental light is absorbed without being reflected on the liquid crystal panel, thereby increasing the contrast ratio.

As described above, although the present invention has been described with reference to limited embodiments and drawings, the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims (20)

Backlight assembly; A liquid crystal display panel provided on the backlight assembly; And Light including a transparent sheet provided on the liquid crystal display panel, a reflection pattern formed on the transparent sheet to induce total reflection of light passing through the liquid crystal display panel, and an external light absorbing portion provided inside the reflection pattern to absorb external light. Functional film; Liquid crystal display device having a. The method of claim 1, The reflective pattern is a liquid crystal display device, characterized in that provided in the wedge shape or trapezoidal shape inside the transparent sheet. The method of claim 2, The side slope of the reflection pattern is a liquid crystal display device, characterized in that 0 to 45 degrees. The method of claim 3, The inclination of the side surface of the reflective pattern is a liquid crystal display device, characterized in that 1 to 5 degrees. The method of claim 1, The reflective pattern is formed on the surface or the inside of the transparent sheet, the liquid crystal display device. The method of claim 1, The reflective pattern is a liquid crystal display device, characterized in that formed in a stripe or wave shape. The method of claim 1, The reflective pattern is a liquid crystal display device, characterized in that provided in a granular shape inside the transparent sheet. The method of claim 1, The external light absorbing unit absorbs light. The method of claim 1, The refractive index of the external light absorbing portion is less than the refractive index of the transparent sheet, the liquid crystal display device. The method of claim 1, Liquid crystal display device characterized in that the glass sheet is further provided on the upper surface of the photovoltaic film. The method of claim 10, Liquid crystal display device characterized in that the anti-reflection film is formed on the upper surface of the glass sheet. In the liquid crystal display device in the optical functional film provided on the front of the liquid crystal display panel, And a transparent pattern, a reflective pattern formed on the transparent sheet to induce total reflection of light passing through the liquid crystal display panel, and an external light absorbing part provided inside the reflective pattern to absorb external light. The method of claim 12, The reflective pattern is a photo-functional film, characterized in that provided in the wedge shape or trapezoidal shape inside the transparent sheet. The method of claim 13, The side slope of the reflective pattern is a light functional film, characterized in that 0 to 45 degrees. The method of claim 14, The side slope of the reflective pattern is a light functional film, characterized in that 1 to 5 degrees. The method of claim 12, The reflective pattern is formed on the surface or the inside of the transparent sheet, the optical functional film. The method of claim 12, The reflective pattern is a photo-functional film, characterized in that formed in a stripe or wave shape. The method of claim 12, The reflective pattern is a photo-functional film, characterized in that provided in a granular shape inside the transparent sheet. The method of claim 12, The external light absorbing portion absorbs light. The method of claim 12, The refractive index of the external light absorbing portion is smaller than the refractive index of the transparent sheet.

Images