KR100813349B1 - Vertical alignment mode liquid crystal display - Google Patents

Abstract

The present invention discloses a vertical alignment mode liquid crystal display capable of high-speed response. According to an aspect of the present invention, there is provided a vertical alignment mode liquid crystal display device comprising: a first substrate having a pixel electrode and a thin film transistor; A second substrate facing the first substrate and having a color filter having a common electrode and a V-shaped groove; And a liquid crystal layer interposed between the first substrate and the second substrate, wherein the unit pixel electrodes disposed in each unit pixel include a plurality of electrode patterns arranged in a matrix form and a plurality of first cross shapes. And a plurality of second slits extending to be inclined from the first slits, respectively. The unit pixel electrode may include a plurality of electrode patterns arranged in a matrix form and a plurality of slits having cross shapes different in length in a first direction and in a second direction perpendicular to the first direction. It features.

Description

Vertical alignment mode liquid crystal display {VERTICAL ALIGNMENT MODE LIQUID CRYSTAL DISPLAY}

1 is a schematic cross-sectional view showing a vertical alignment mode liquid crystal display device according to a first embodiment of the present invention;

FIG. 2 is a plan view illustrating the pixel electrode illustrated in FIG. 1. FIG.

3 is an enlarged view of FIG. 2 enlarged.

4 is a schematic plan view showing a pixel electrode according to Embodiment 2 of the present invention;

FIG. 5 is an enlarged view of FIG. 4 enlarged. FIG.

Explanation of symbols on the main parts of the drawings

102: first substrate 104: second substrate

106: liquid crystal layer 110: lower glass substrate

120: insulator 130: pixel electrode

132: pixel electrode pattern 134: slit

135: first slit 136: second slit

140: lower alignment layer 150: upper glass substrate

160: color filter 162: groove

170: common electrode 180: upper alignment layer

The present invention relates to a liquid crystal display device, and more particularly, to a vertical alignment mode liquid crystal display device capable of high-speed response.

In the vertical alignment mode liquid crystal display device, a liquid crystal having negative dielectric anisotropy is interposed between the upper and lower substrates, a vertical alignment layer is formed on opposite surfaces of the upper and lower substrates, and a polarizing plate is attached to each of the rear surfaces of the upper and lower substrates. Have At this time, each of the opposing surfaces of the upper and lower substrates is provided with a liquid crystal drive electrode, and the polarization axes of the upper and lower polarizing plates are attached to be perpendicular to each other.

In the vertical alignment mode liquid crystal display, before the electric field is formed, the liquid crystal molecules are arranged perpendicular to the substrate under the influence of the vertical alignment layer. At this time, the screen becomes dark because the vertical polarizers cross vertically.

On the other hand, when an electric field is formed between the driving electrodes of the upper and lower substrates, the liquid crystal molecules are distorted to be perpendicular to the shape of the electric field according to the liquid crystal property of negative dielectric anisotropy. As a result, light is transmitted through the liquid crystal molecules, and the screen is white. At this time, since the liquid crystal molecules are rod-shaped, the refractive indices of the long axis and the short axis are different from each other as well as the dielectric constant. Therefore, the refractive index is different depending on the direction in which the liquid crystal molecules are viewed, resulting in a difference in viewing angle between the front view and the side view.

Therefore, in order to solve this problem, conventionally, a pixel electrode of a lower plate is formed in a slit shape in one unit pixel to form multiple domains when forming an electric field. In other words, when the electric field is formed between the pixel electrode and the common electrode, the direction in which the liquid crystal molecules are distorted is compensated, thereby compensating anisotropy for the long and short axes of the liquid crystal molecules.

In the case of the liquid crystal display device in the vertical alignment mode, a detailed design is required to secure dynamic stability such as control of the disclination line of the liquid crystal according to the shape of the electrode pattern of the substrate and the projection using the resin. However, there is a disadvantage in that protrusions or electrode patterns must be additionally formed using the resin. Thus, a valley vertical alignment mode has been proposed in which color filter resins are carved out to form grooves without the need for additional processing, and the vertically aligned liquid crystals are controlled under an electric field using them.

However, near the resin groove, the liquid crystal has a property to lie parallel to the resin groove with two degrees of freedom due to weak potential energy in the direction perpendicular to the resin groove in the direction of the liquid crystal director. Therefore, in the case of using a liquid crystal having an infinite pitch, the rotational direction of the liquid crystal becomes irregular due to two degrees of freedom, resulting in unstable driving, and hence, a decrease in response speed.

In order to solve this problem, the chiral dopant was added to the liquid crystal to control the rotation direction. However, in the case of using a liquid crystal having a pitch such as the addition of the chiral dopant, an unstable factor is caused in the orientation stability, the characteristics are deteriorated in terms of contrast ratio and viewing angle, and act as a disadvantage in securing a cell gap process margin. do.

Accordingly, an object of the present invention is to provide a vertical alignment mode liquid crystal display device capable of securing dynamic stability and improving a viewing angle.

One preferred embodiment of the present invention for achieving the above object is a first substrate having a pixel electrode and a thin film transistor; A second substrate facing the first substrate and having a color filter having a common electrode and a V-shaped groove; And a liquid crystal layer interposed between the first substrate and the second substrate, wherein the unit pixel electrodes disposed in each unit pixel include a plurality of electrode patterns arranged in a matrix form and a plurality of first cross shapes. A slit and a plurality of second slits extending to be inclined from the first slits, respectively, are provided.

Here, the second slit has an inclination angle of 50 to 60 ° with the first slit.

In addition, another preferred embodiment of the present invention for achieving the above object is a first substrate having a pixel electrode and a thin film transistor; A second substrate facing the first substrate and having a color filter having a common electrode and a V-shaped groove; And a liquid crystal layer interposed between the first substrate and the second substrate, wherein each unit pixel electrode disposed in each unit pixel includes a plurality of electrode patterns arranged in a matrix form, a length in a first direction, and a length in the first direction. Provided is a vertical alignment mode liquid crystal display comprising a plurality of slits having a cross shape different in length in a second direction perpendicular to the direction.

Here, the first slit having a cross shape having a length in the first direction longer than the length of the second direction and a second slit having a cross shape having a length short in the first direction than the length in the second direction are alternately arranged. . The ratio of the length in the first direction and the length in the second direction is about 1: 1.5 to 1: 2.

(Example)

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

Example 1

1 is a schematic cross-sectional view showing a vertical alignment mode liquid crystal display device according to a first embodiment of the present invention.

Referring to FIG. 1, the vertical alignment mode liquid crystal display device 100 includes a first substrate 102, a second substrate 104, and a liquid crystal layer interposed between the first substrate 102 and the second substrate 104. It consists of 106.

The first substrate 102 includes a lower glass substrate 110, an insulator 120, a pixel electrode 130, and an alignment layer 140. The insulating layer 120 and the pixel electrode 130 are sequentially disposed on the inner surface of the lower glass substrate 110, and the lower alignment layer 140 is interposed between the liquid crystal layer 106 and the pixel electrode 130.

Although not shown, a plurality of gate lines and data lines are formed on the lower glass substrate 110, and a thin film transistor is formed at a point where the gate lines and the data lines intersect.

The second substrate 104 includes an upper glass substrate 150, a color filter 160, a common electrode 170, and an alignment layer 180. Red, green, and blue color filters 160 and the common electrode 170 are sequentially disposed on the inner surface of the upper glass substrate 150.

Although not shown, the color filter 160 is divided into unit pixels by a black matrix formed on the upper glass substrate 150. In addition, an upper alignment layer 180 is interposed between the liquid crystal layer 106 and the common electrode 170.

In particular, the color filter 160 is formed with a V-shaped groove 162 at a predetermined angle. Therefore, the common electrode 170 and the upper alignment layer 180 are formed on the color filter 160 including the V-shaped groove 162. Here, the V-shaped groove 162 is formed at the same time when the color filter 160 is formed.

Therefore, before the electric field is formed, the liquid crystals of the liquid crystal layer 106 are arranged perpendicular to the glass substrates 110 and 150 due to the influence of the vertical alignment layers 140 and 180. It is twisted to be perpendicular to leak light. At this time, the distortion of the electric field occurs near the V-shaped groove 162 so that the liquid crystals form a multi-domain. As a result, the deterioration in image quality due to the refractive index anisotropy of the liquid crystal is compensated. In addition, the V-shaped groove 162 is formed at the same time when forming the color filter, it is not necessary to add a separate mask and process.

In addition, although not shown, in the vertical alignment mode liquid crystal display device 100 of the present invention, a polarizing plate is attached to each of the lower surfaces of the lower glass substrate 110 and the upper glass substrate 150 so that the polarization axes cross each other. .

FIG. 2 is a plan view illustrating the pixel electrode illustrated in FIG. 1, and FIG. 3 is an enlarged view of FIG. 2.

2 and 3, the unit pixel electrode 130 includes a plurality of electrode patterns 132 and slits 134. The electrode pattern 132 is formed in a matrix form in the unit pixel electrode 130. The groove 162 overlaps the center of each of the plurality of electrode patterns 132.

The slit 134 includes a first slit 135 and a second slit 136. The first slit 135 has a cross shape. The first slit 135 may have a cross shape having a length in a first direction and a length in a second direction perpendicular to the first direction. A plurality of second slits 136 extend from the first slits 135 to be inclined with the first slits 135. The interval between the second slits 136 is preferably within 4㎛.

The inclination direction of the second slit 136 is an arbitrary direction in which the liquid crystal is to rotate. When the inclination angle is too small, it is difficult to control the rotation direction of the liquid crystal, and when the inclination angle is too large, the angle formed with the transmission axis of the polarizing plate is small, which may cause a decrease in transmittance. Therefore, it is preferable that the second slit 136 be inclined at an angle θ of about 50 to 60 degrees with the first slit 135.

In addition, as illustrated in FIG. 2, in the unit pixel electrode 130, the liquid crystal rotation directions (arrows) of the adjacent electrode patterns 132 are symmetrical with each other by the second slit 136.

Therefore, the vertical alignment mode liquid crystal display device of the present invention can use a liquid crystal having an infinite pitch, and can also improve dynamic stability and viewing angles in up, down, left, right, and diagonal directions.

Example 2

4 is a schematic plan view illustrating a pixel electrode according to a second exemplary embodiment of the present invention, and FIG. 5 is an enlarged view of FIG. 4.

The vertical alignment mode liquid crystal display according to the present exemplary embodiment is the same as the vertical alignment mode liquid crystal display of Example 1 except for the shape of the slits formed in the unit pixel electrode.

4 and 5, the unit pixel electrode 230 includes a plurality of electrode patterns 232 and slits 234. The electrode pattern 232 is formed in a matrix form within the unit pixel electrode 230. The groove 262 overlaps the center of each of the plurality of electrode patterns 232.

The slit 234 has a cross shape. Specifically, the slit 234 has a cross-shaped first slit 235 having a length in a first direction longer than a length in a second direction and a cross-shaped material having a length shorter than a length in a second direction. The two slits 236 are alternately arranged. The slit 234 preferably has a length ratio of unidirectional length to long length of about 1: 1.5 to 1: 2.

Therefore, due to the alternating arrangement of the first slit 235 and the second slit 236, as shown in FIG. 4, the liquid crystal rotation direction (arrow) in the adjacent electrode pattern 232 is symmetrical.

Although not shown, a plurality of auxiliary slits may extend from the slits 234 to be inclined.

Accordingly, the vertical alignment mode liquid crystal display may use liquid crystals having an infinite pitch, and may improve dynamic stability and viewing angles in up, down, left, right, and diagonal directions.

Hereinbefore, the present invention has been described with reference to preferred embodiments, but those skilled in the art can variously modify and modify the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated that it can be changed.

The vertical alignment mode liquid crystal display according to the present invention controls the rotation direction of the liquid crystal by forming a slit on the pixel electrode surface. Therefore, it is possible to secure the dynamic stability by reducing the degree of freedom of the liquid crystal in the vicinity of the color filter groove, it is possible to solve the problem caused by using the liquid crystal having a pitch. In addition, the rotation direction of the liquid crystal may be adjusted according to the shape of the slit, thereby improving the viewing angle in the diagonal direction.

Claims (5)

A first substrate having a pixel electrode and a thin film transistor; A second substrate facing the first substrate and having a color filter having a common electrode and a V-shaped groove; And And a liquid crystal layer interposed between the first substrate and the second substrate. The unit pixel electrodes disposed in each unit pixel may include a plurality of electrode patterns arranged in a matrix and having the V-shaped grooves overlapped at their centers, a plurality of first slits having a cross shape, and the first slits. And a plurality of second slits extending to be inclined in the center direction. The liquid crystal display of claim 1, wherein the second slit has an inclination angle of 50 to 60 degrees with the first slit. A first substrate having a pixel electrode and a thin film transistor; A second substrate facing the first substrate and having a color filter having a common electrode and a V-shaped groove; And And a liquid crystal layer interposed between the first substrate and the second substrate, The unit pixel electrodes disposed in each unit pixel are arranged in a matrix and have a plurality of electrode patterns in which the V-shaped grooves overlap each center, a length in a first direction, and a length in a second direction perpendicular to the first direction. The vertical alignment mode liquid crystal display, characterized in that it comprises a plurality of sillets having different cross shapes. The cross-shaped first slit of which the length in the first direction is longer than the length in the second direction and the cross-shaped second slit in which the length in the first direction is shorter than the length in the second direction are defined. The vertical alignment mode liquid crystal display, characterized in that arranged alternately. The liquid crystal display of claim 3, wherein a ratio of the length in the first direction and the length in the second direction is 1: 1.5 to 1: 2.

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