KR20030039601A - Liquid crystal display device having a light refraction portion - Google Patents

Abstract

PURPOSE: A liquid crystal display device with a light refracting part is provided to increase the intensity of incident light in the upper and lower forward direction of an LCD panel by forming a light refracting part on a surface of an upper substrate, thereby improving the gray level inversion and the viewing angle of the upper and lower parts of the LCD panel. CONSTITUTION: A liquid crystal display device with a light refracting part includes a display unit(100), a backlight assembly(200) for supplying light to the display unit, and a mold frame(300) for receiving and fixing the display unit and the backlight assembly. The display unit includes a liquid crystal display panel and a driving circuit part(180) for supplying driving signals including display information to the LCD panel. The LCD panel includes a first substrate having first electrodes and a light refracting part for refracting the light passing through the liquid crystal to the environmental parts of the first substrate, a second substrate having second electrodes for generating electric fields with the first electrodes and facing the first substrate, and a liquid crystal layer interposed between the substrates.

Description

Liquid crystal display device having a light refraction portion {Liquid crystal display device having a light refraction portion}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which a view angle is improved by relieving or eliminating grayscale inversion by refracting light passing through a liquid crystal in the vertical direction of the liquid crystal panel.

Recently, information processing apparatuses have been rapidly developed to have various forms and functions, and faster information processing speeds. Accordingly, display apparatuses capable of displaying processed information have also been variously developed. Recently, a liquid crystal display (LCD) device, which is a flat panel display device that can realize small size, light weight, and low power consumption, has been developed and widely used. In the early stages of the development of the LCD device, it was limited to small display devices such as digital clocks and LCD screens of electronic calculators, but in recent years, the scope of application is rapidly expanding to computer monitors, wall-mounted television screens, and other large display devices. .

In general, an LCD device is a display device that uses a difference in transmittance of light that varies according to an arrangement structure of liquid crystal molecules between an upper substrate and a lower substrate. Various types of LCD devices are presented based on the type of liquid crystal, the arrangement structure, and a driving signal application method. It is. Recently, an active matrix liquid crystal display device (hereinafter referred to as AMLCD) that applies driving signals to all pixels constituting the screen individually in order to meet the tendency of increasing display information amount and thus display area. ) Is being actively researched. In particular, a thin film transistor liquid crystal display (TFT-LCD) using a thin film transistor as a switching element for controlling a driving signal of each pixel can be applied to a large area glass substrate by a low temperature process, and can be sufficiently driven even at a low voltage. It is the most widely used AMLCD because of its advantages.

Such a TFT-LCD device includes a liquid crystal display panel, which is a unit for displaying display information, a display unit including a driving circuit for driving the display information, a backlight assembly for supplying light for screen display, and fixing and accommodating the display unit and the backlight assembly. It consists of a mold frame. The liquid crystal display panel is formed of a C / F substrate having a color filter for realizing color, a switching element such as a thin film transistor, a TFT substrate having pixel electrodes, and a liquid crystal inserted between the C / F substrate and the TFT substrate. do. Currently, the most commercially available TFT-LCD apparatus has 90 vertically aligned vertical alignment layers as the liquid crystal, a nematic liquid crystal mixed with cholesteric liquid crystal, and twisted between the two substrates. ° TN type is the mainstream.

As the application range of LCD devices is expanded to large display devices, one of the problems is the viewing angle. The viewing angle is a concept representing a position range of a user who can recognize information displayed on a liquid crystal panel, and means an angle range that can recognize information displayed in up, down, left and right directions with respect to the front of the liquid crystal panel. Usually, the viewing angle range of the TFT-LCD represents an area where the contrast ratio is 10 or more and there is no gradation inversion when driven with 8 gradations. The passive matrix LCD device displays only two gradations, so the viewing angle can be determined only by the contrast ratio.However, a passive matrix LCD device or color in a graphic mode using multiple gradations can be implemented. For TFT-LCD devices, it is more important to realize good image quality than to improve contrast.

1 is a graph showing a relationship between a viewing angle and a contrast ratio of a conventional TN type TFT-LCD device.

In Fig. 1, the measurement of the viewing angle is performed by setting the angle when the eye of the user and the screen of the liquid crystal panel are in front to 0 ° and rotating the liquid crystal panel in the -90 ° to 90 ° direction in the vertical direction. The contrast ratio at level 8) was measured. In the TN type LCD device, the overall display characteristics of the liquid crystal panel are influenced by the display characteristics in the up-down direction rather than the left-right direction. The contrast ratio is a dimensionless value defined as the ratio of the luminance value of the white state to the luminance value of the black state at the front center of the liquid crystal panel, and is a quantitative value indicating how clearly the information displayed on the screen appears. to be. In this case, graph 1 is a case where a gray voltage forming a black state is applied, and graph 8 is a case where a gray voltage forming a white state is applied. Graphs 2 to 7 show a case where an intermediate gradation voltage is applied to express colors between the black state and the white state.

According to FIG. 1, in the center of the screen, the contrast ratio increases sequentially from the black state to the white state according to the increase of the gradation voltage, so that the expression color at each gradation level can be distinguished. As the position is changed up and down, it is gradually weakening. Particularly, when the viewing angle is greater than or equal to a specific value (a ₁ ), the contrast ratio of the low gray scale voltage becomes superior to the contrast ratio of the high gray voltage, and all of the information displayed on the screen is expressed in the color of the low gray voltage so that the information cannot be distinguished. (Gradation inversion phenomenon). Therefore, the viewing angle is limited to -a ₁ ° to a ₁ °, and in order to secure a wide viewing angle, it is necessary to increase the value of a ₁ , which is an angle at which grayscale inversion occurs. In general, it is known that the range of the viewing angle in consideration of gradation inversion is formed over -60 ° to 60 °.

Wide viewing angle technology to improve the gray level inversion phenomenon and to secure a wide viewing angle. A pixel is divided into a plurality of regions, and the orientation of the liquid crystal molecules is changed in each region, so that the characteristics of the pixels are included. Multi-domain segmentation technology that makes the average value of domain characteristics, Optical compensation technology to reduce the phase change with respect to the change of viewing direction by using retardation film, and the direction of the liquid crystal is applied in the plane parallel to the alignment film by applying the electric field in the horizontal direction. The twisted Plane Switch (IPS) technique, the Vertical Alignment technique using a vertical alignment layer and a liquid crystal with negative dielectric anisotropy, and the like are known.

However, the optical compensation technique has a problem that the asymmetric visual characteristics and gradation inversion characteristics remain intact, so that the viewing angle expansion effect is not much. The multi-domain segmentation technique uses several additional photolithography and rubbing processes. There is a problem that the number of processes increases and the yield decreases because it has to go through. In addition, in the multi-zone segmentation technology, when the same compensation film is applied, there is an area that is compensated and an area that is not compensated, and the effort to improve the viewing angle is improved by forming a relationship in which the gray level inversion and the viewing angle are opposed to each other. There is a problem that becomes impossible.

Accordingly, an object of the present invention is to relieve or eliminate the grayscale inversion occurring in the upper and lower portions of the liquid crystal panel by refracting the light passing through the liquid crystal toward the upper and lower directions of the liquid crystal panel while minimizing the addition of additional processes. It is to provide a liquid crystal display device that can improve the.

1 is a graph showing a relationship between a viewing angle and a contrast ratio of a conventional TN type TFT-LCD device.

2A is an exploded perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2B is a structural diagram schematically showing the structure of a unit cell formed in the liquid crystal display panel shown in FIG. 2A.

3 is a structural diagram schematically illustrating a structure of a unit cell in which a TFT substrate is formed on the liquid crystal layer.

4A to 4C and FIGS. 5A to 5C are cross-sectional views showing cross-sections of the light refractive portions according to the embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: display unit 110: color filter substrate

120 TFT substrate 130 Liquid crystal

140,150 polarizer 170 liquid crystal display panel

180: driving circuit unit 200: backlight assembly

210: Light guide plate 220: Condensing sheet

230: reflector 240: light source

300: Mold Frame

In order to achieve the above object, the present invention includes: i) a first substrate including a first electrode and having a photorefractive portion for refracting light, and opposing the first substrate to form an electric field together with the first electrode. And a liquid crystal layer disposed between the lower portion of the first substrate and the upper portion of the second substrate, wherein the optical refraction portion is configured to pass light passing through the liquid crystal to the second substrate. A display unit including a liquid crystal display panel refracted to a peripheral portion and ii) a driving circuit unit for supplying a driving signal including display information to the liquid crystal display panel; A backlight assembly supplying light for displaying the display information to the display unit; And a container configured to receive and fix the display unit and the backlight assembly.

In this case, the first substrate further includes a color filter for realizing a color on a surface facing the upper surface of the second substrate, and an over-coating layer for planarizing the first substrate. The part is directly formed on the surface of the coating layer or the first substrate on which the color filter is formed. Alternatively, the first substrate may be a TFT substrate further comprising a thin film transistor positioned on a surface opposite the upper surface of the second substrate to control a current applied to the first electrode. The photorefractive portion may be formed on a thin film transistor passivation layer or a gate passivation layer formed on the TFT substrate.

The photorefractive portions are formed of a plurality of grooves recessed in the advancing direction of light from the surface of the flat horizontal film, and the plurality of grooves are arranged parallel to each other in a direction perpendicular to the average tilt direction of the liquid crystal while maintaining a constant interval. The light incident to the groove among the light passing through the liquid crystal is refracted to both side ends of the first substrate, and the light incident to the horizontal film, which is a flat film between the grooves, goes straight to the front direction of the first substrate. At this time, the groove is composed of a concave curved surface or two inclined plane.

Therefore, according to the present invention, display characteristics can be improved at the upper and lower ends of the liquid crystal display panel by eliminating or suppressing the gray level inversion by increasing the amount of light in the upper and lower directions of the liquid crystal display panel.

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

2A is an exploded perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2B is a structural diagram schematically illustrating a structure of a unit cell formed in the liquid crystal display panel illustrated in FIG. 2A.

2A and 2B, the liquid crystal display 900 may include a display unit 100 for displaying an image, a backlight assembly 200 for supplying light to the display unit 100, and the display unit 100. And a mold frame 300 accommodating the backlight assembly 200.

The display unit 100 includes a liquid crystal display panel 170 for displaying an image and a driving circuit unit 180 for supplying a driving signal including display information to the liquid crystal display panel 170.

In an exemplary embodiment, the liquid crystal display panel 170 may include a color filter substrate 110, which is a first substrate for implementing color, and a TFT substrate 120, which is a second substrate having a switching element opposed to the color filter substrate 110. The liquid crystal 130 is positioned between the color filter substrate 110 and the TFT substrate 120.

The liquid crystal 130 uses a twisted nematic liquid crystal (hereinafter, 90 ° TN type liquid crystal) at 90 ° as an embodiment. Accordingly, the major axis direction of the liquid crystal 130 forms an angle of 90 ° with each other in the vicinity of and in the center of the TFT substrate 120 and the color filter substrate 110. Hereinafter, an average tilt direction of the vertical field horizontally aligned liquid crystal is defined as a first direction and a direction perpendicular to the second direction. Accordingly, the first direction generally coincides with the direction of the liquid crystal director located in an area adjacent to the surfaces of the TFT substrate 120 and the color filter substrate 110. In addition, one side of the front surface of the liquid crystal display panel 170 along the first direction is defined as an upper front surface of the liquid crystal display panel, and the other side opposite thereto is defined as a lower front surface of the liquid crystal display panel.

The color filter substrate 110 has a color filter 112 formed with a color pixel for realizing color, and protects the color filter 112 and an over-coating layer which is a surface protective film for flattening the surface of the substrate. 114, a common electrode 116 which is a first electrode formed on the surface of the coating layer 114, and an alignment layer 118 for aligning liquid crystals formed on the surface of the common electrode 116 are sequentially stacked. In this case, a light refraction portion 115 is formed on the surface of the coating layer 114 to refract light incident on the color filter substrate 110 to the upper and lower surfaces of the liquid crystal display panel 170. have.

The light refracting portion 115 has a groove shape excavated by a predetermined depth in the traveling direction of the light from the coating layer 114. The groove may be formed with a concave curved surface concave with respect to the traveling direction of the light, or the first inclined plane inclined in a right upward direction and the second inclined plane inclined in a left upward direction may be adjacent to each other. The light refracting portion 115 is formed such that a plurality of grooves are arranged in parallel in the second direction at regular intervals. Therefore, the light incident on the color filter substrate 110 is refracted by the light refracting portion 115 and is incident in the upper front and lower front directions of the liquid crystal display panel 170. Accordingly, the light transmittance is increased by increasing the amount of light incident on the upper and lower front surfaces of the liquid crystal display panel 170 as compared with the related art. Accordingly, display performance of the liquid crystal display may be improved by alleviating or eliminating the gray level inversion phenomenon occurring in the upper and lower surfaces of the liquid crystal display panel 170. The light refracting portion 115 is permanently described below.

The TFT substrate 120 includes a TFT (not shown), a capacitor (not shown), a switching element provided for each pixel, a gate and a data line (not shown) connecting them to each other in a matrix form, and The pixel electrode 122 is a second electrode which forms an electric field together with the common electrode 116 which is a first electrode. The TFT is connected to the source electrode and the drain electrode by a source electrode receiving a data signal that is a part of the driving signal, a drain electrode transferring the data signal from the source electrode to the pixel electrode, and a gate signal that is a part of the driving signal. It has a gate electrode for controlling. In this case, the gate electrode is formed by a bottom gate method positioned below the source electrode and the drain electrode. A passivation layer 124 is deposited on the upper surface of the TFT substrate 120 to protect the switching element and the pixel electrode 122 from external scratching or contamination. In this case, the common electrode 116 and the pixel electrode 122 are formed of an indium tin oxide (ITO) film, which is a transparent conductive film. Polarizers 140 and 150 are formed below the TFT substrate 120 and above the color filter substrate 110 to selectively pass light in a predetermined direction.

The driver circuit unit 180 is installed to include a driver IC in a peripheral portion of the TFT substrate 120. The driving circuit takes the form of a printed circuit board and the circuit components are mounted using surface mounting technology for thinning and high density mounting. In this case, the driving integrated circuit is manufactured in the form of a tape carrier package (TCP) and connected to the printed circuit board and the TFT substrate 120.

A backlight assembly 200 is provided below the display unit 100 to supply light to the liquid crystal display panel 170. The backlight assembly 200 may include a light guide plate 210 and a display unit for irradiating a light source 240 for generating light to the display unit 100 positioned above the light generated from the light source 240. Condensing sheet 220 for improving the light collecting performance of the light incident to the 100 and a reflecting plate 230 for reflecting the leakage light toward the display unit 100.

The mold frame 300 has a rectangular parallelepiped shape having an upper surface open and has four sidewalls and one bottom surface. Openings are formed on the bottom surface of the printed circuit board by bending the printed circuit board along the outer surface of the mold frame 300.

The liquid crystal display is completed by accommodating the display unit 100 and the backlight assembly 200 in the mold frame 300 and firmly fixing a bottom chassis and a top chassis (not shown).

When a driving signal is applied to the liquid crystal display device 900 having the above structure through the driving circuit unit 180, an electric field is formed between the pixel electrode 122 and the common electrode 116, and the direction of the electric field is changed. Accordingly, the liquid crystal 130 is arranged. Therefore, the degree to which the light passing through the TFT substrate 120 reaches the common electrode 116 is determined by the arrangement of the liquid crystal 130 by the electric field. In this case, the light passing through the common electrode 116 passes through the light refraction portion 115 and is respectively refracted in the direction of both side ends of the color filter substrate 110 on the surface of the light refraction portion, thereby forming an upper portion of the liquid crystal display panel. Increase the amount of light transmitted from the front and lower front surfaces. Therefore, as the amount of linear light decreases so that the transmittance in the front direction decreases, the transmittance in the upper and lower front surfaces of the liquid crystal display panel is increased, thereby improving or eliminating grayscale inversion.

The above-described embodiment has a structure in which light generated in the backlight passes through the color filter substrate via the TFT substrate and the liquid crystal layer to display an image. The image can also be displayed by.

3 is a structural diagram schematically illustrating a structure of a unit cell in which a TFT substrate is formed on the liquid crystal layer. In this embodiment, the position of the color filter substrate and the TFT substrate are shifted with respect to the liquid crystal layer as compared with the unit cell shown in FIG. 2B. Accordingly, the position of the optical refraction portion is formed on the lower surface of the TFT substrate. Except for the same structure. Therefore, the same reference numerals are used for the same members as those shown in Fig. 2B.

Referring to FIG. 3, a passivation layer 124 is provided on a bottom gate TFT substrate to prevent scratching and contamination of the thin film transistor, and a passivation layer 124 passes through the passivation layer 124. A photorefractive portion 125 is formed for refracting a light to both side ends of the TFT substrate 120. Therefore, the light supplied from the backlight assembly is first spectroscopically introduced by the color filter 122 into the liquid crystal layer, and the light passing through the liquid crystal layer is transferred onto the liquid crystal display panel 170 via the TFT substrate. To form. In this case, in the case of the top gate type in which a gate electrode is formed on the transistor as a thin film transistor of the TFT substrate, the photorefractive portion may be formed on the gate protective layer.

4A to 4C and FIGS. 5A to 5C are cross-sectional views illustrating a cross section obtained by cutting a light refraction portion in a first direction according to an embodiment of the present invention. For convenience, the light refraction portion will be described on the basis of that formed on the color filter substrate.

Referring to FIG. 4A, the light refracting portion 115 is formed as a plurality of grooves excavated in the advancing direction of light passing through the liquid crystal layer from the surface of the coating layer 114 as an embodiment. A concave curved surface 1152 formed concave with respect to the traveling direction is provided. In this case, the grooves are arranged in parallel to each other in a second direction perpendicular to the average tilt direction of the liquid crystal so that the light incident to the grooves of the light passing through the liquid crystal is refracted to both side ends of the first substrate and the groove Light incident on the coating layer 114 therebetween is directed to the front direction of the liquid crystal display panel.

The concave curved surface 1151 is formed of a first region 1151a having a positive slope in contact with a curved surface and a second region 1151b having a negative slope. The light ⓐ incident to the first zone 1151a is refracted by the curved surface and transmitted to the upper front surface of the liquid crystal display panel, and the light ⓑ incident to the second zone 1151b is refracted by the curved surface. The light is transmitted through the front lower surface of the liquid crystal display panel. Accordingly, the refractive index of the coating layer 114 should be at least 1, and the degree of refraction toward the upper front surface or the lower front surface of the liquid crystal display panel varies according to the difference in refractive index. Preferably, the refractive index of the coating layer is formed to be 1.5.

The photorefractive portions 115 are formed in parallel to each other in a second direction to have a predetermined interval so that a horizontal film 1152 in which the surface layer of the coating layer 114 is not deformed is formed between the concave curved surfaces 1151 adjacent to each other. It is. In addition, the horizontal film 1152 is formed between both side ends of the coating layer 114 in the first direction and the concave portion. The light ⓔ incident on the horizontal film 1152 is straight without being refracted and goes straight in front of the liquid crystal display panel. Therefore, although all of the light incident perpendicularly to the coating layer 114 is emitted in the front direction of the liquid crystal display panel as straight light, a part of the incident light is refracted by the refraction unit according to the present invention. Emitted in the upper front and lower front direction of. Therefore, instead of partially reducing the amount of light emitted to the front of the liquid crystal display panel, the amount of light emitted to the upper and lower front surfaces may be increased to alleviate or eliminate the gray level inversion phenomenon occurring at the upper and lower front surfaces of the liquid crystal display panel. .

Meanwhile, the concave curved surface 1151 may be formed as a curved surface having different curvatures from each other as needed. As shown in FIG. 4B, the curvature of the first region 1151a is made smaller than the curvature of the second region 1151b to further increase the amount of light emitted from the upper front surface of the liquid crystal display panel. You can. Therefore, the light can be projected to an area in which the gray level inversion effect is further required among the upper and lower surfaces of the LCD panel. When the curvature of the second zone 1151b is formed to be infinite, the light refraction portion 115 formed in a curved surface and a plane may be formed. In addition, as shown in FIG. 4C, the horizontal film 1152 may be configured to have a convex shape with respect to the traveling direction of the light, thereby further improving the concentration of the straight light.

As shown in FIG. 5A, the first slope 1151 a and the second slope sloped to the left and the first slope plane 1153 inclined to the upper right by forming the curvature of both the first zone 1151 a and the second zone 1151 b to infinity. The groove may be configured in a plane 1154. In this case, the amount of light that is refracted to the upper and lower front surfaces of the liquid crystal display panel is determined by the angle between the first and second inclined planes 1153 and 1154 to the surface of the coating layer 114. In addition, when it is necessary to strengthen the component of the straight light for the liquid crystal display panel, as shown in FIG. 5B, the horizontal portion 1155 is disposed between the first inclined plane 1153 and the second inclined plane 1154. It is formed so that the cross-section of the light refractive portion 115 has a trapezoidal shape. Accordingly, the light incident on the horizontal film 1152 and the horizontal portion 1155 becomes straight light emitted in a front direction of the liquid crystal display panel, and the first inclined plane 1153 and the second inclined plane 1154. The light emitted by) may be emitted in the upper front and lower front directions of the liquid crystal display panel to mitigate or eliminate gray level inversion. In addition, as shown in FIGS. 5A and 5C to set different amounts of light emitted in the upper and lower front directions of the liquid crystal display panel, an outermost horizontal film is formed in the upper or lower end of the coating layer 114 in the first direction. It can be formed only in any of.

4A to 4C and 5A to 5C, when the light refracting portion 115 has a predetermined curvature, the light is uniformly refracted at various angles, but is inclined plane having an infinite curvature. If formed, there is a difference that the light can be refracted only at a certain angle.

The light refractive portion 115 may be formed by patterning the coating layer 114 to have a predetermined shape in the process of forming the coating layer 114. Therefore, no additional process for forming the light refractive portion 114 is required. Accordingly, there is an advantage in that gray scale inversion can be improved without changing the conventional liquid crystal display panel manufacturing process.

In the above embodiment, in order to improve the vertical viewing angle, a plurality of grooves are formed in parallel with the second direction, but in order to improve the horizontal viewing angle, it is sufficient to change the forming direction of the groove in the first direction. Therefore, not only the vertical viewing angle but also the horizontal viewing angle can be improved through the same configuration as described above.

According to the present invention, the light refraction portion is formed on the upper substrate surface of the liquid crystal display panel without an additional process to increase the amount of light incident in the upper front and lower front directions of the liquid crystal display panel, thereby improving gray level inversion. Therefore, the display characteristics of the liquid crystal display can be improved by improving the viewing angles on the upper and lower surfaces of the liquid crystal display panel.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will 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 that you can.

Claims (13)

i) a first substrate comprising a first electrode, the first substrate having a photorefractive portion for refracting light, and a second substrate facing the first substrate and having a second electrode for forming an electric field together with the first electrode; And a liquid crystal layer positioned between the lower portion of the first substrate and the upper portion of the second substrate, wherein the optical refraction portion refracts the light passing through the liquid crystal to the peripheral portion of the first substrate; A display unit including a driving circuit unit for supplying a driving signal including display information to the liquid crystal display panel; A backlight assembly for supplying light for displaying the display information to the display unit; And And a container configured to receive and fix the display unit and the backlight assembly. The method of claim 1, wherein the first substrate further comprises a color filter for realizing color on a surface opposite the upper surface of the second substrate, and an over-coating layer for planarizing the first substrate. Liquid crystal display device characterized in that. The liquid crystal display device of claim 2, wherein the light refraction portion is formed on a surface of the coating layer. The liquid crystal display device according to claim 2, wherein the light refraction portion is formed on the first substrate. The method of claim 1, wherein the first substrate further comprises a thin film transistor positioned on a surface of the second substrate facing the upper surface of the second substrate to control a current applied to the first electrode. Liquid crystal display device. The thin film transistor of claim 5, wherein the thin film transistor includes a source electrode receiving a data signal that is a part of the driving signal, a drain electrode transferring the data signal from the source electrode to the first electrode, and a lower portion of the source electrode and the drain electrode. A bottom-gate method having a gate electrode positioned to control the connection between the source electrode and the drain electrode by a gate signal which is part of the driving signal, and a thin film transistor passivation layer for protecting the thin film transistor And the light refraction portion is formed on the thin film transistor passivation layer. The thin film transistor of claim 5, wherein the thin film transistor includes a source electrode receiving a data signal which is a part of the driving signal, a drain electrode transferring the data signal from the source electrode to the first electrode, and an upper portion of the source electrode and the drain electrode. A top gate having a gate electrode positioned to control the connection between the source electrode and the drain electrode by a gate signal which is a part of the driving signal, and a gate protection layer formed on the gate electrode to protect the thin film transistor And the light refraction portion is formed on the gate passivation layer. The liquid crystal display of claim 1, wherein the light refraction portion is formed of a plurality of grooves recessed in the advancing direction of light from the surface of the flat horizontal film, and the plurality of grooves are perpendicular to the average tilt direction of the liquid crystal while maintaining a constant interval. The light incident to the groove among the light passing through the liquid crystal in parallel with each other in the direction is refracted to both side ends of the first substrate, and the light incident to the horizontal film, which is a flat film between the grooves, faces the front of the first substrate. The liquid crystal display device which goes straight to a direction. The method of claim 8, wherein the groove has a concave curved surface formed concave with respect to the traveling direction of the light, wherein the concave curved surface is formed of a first region having a positive slope and a second region having a negative slope And the light incident to the first zone is refracted to the first side end of the first substrate, and the light incident to the second zone is refracted to the second side end facing the first side end. 10. The method of claim 9, wherein the concave curved surface is formed differently the curvature of the first zone and the second zone can be adjusted to the direction and the amount of light refracted to the first side end and the second side end differently. Liquid crystal display device. The method of claim 8, wherein the groove comprises a first inclined plane for refracting the light to the first side end of the first substrate and a second inclined plane for refracting the light to the second side end of the first substrate Liquid crystal display device. 12. The liquid crystal display device according to claim 11, wherein the groove further includes a horizontal plane intersecting with the first inclined plane and the second inclined plane and parallel to the horizontal film. 9. The liquid crystal according to claim 8, wherein the horizontal film between adjacent grooves and between the groove and the side end portion of the first substrate is a convex curved surface formed convexly in the traveling direction of light to improve the concentration of light. Display.