KR20070081262A - Ocb mode liquid crystal display device - Google Patents

Abstract

An OCB(Optically Compensated Bend) mode LCD(Liquid Crystal Display) is provided to improve a liquid crystal molecule transfer rate from a splay state to a bend state without deterioration of an aperture ratio by making a rubbing direction of an alignment layer in an orthogonal direction with respect to a pixel area to form a slightly twist domain in an area where a noise field is generated, and using this as a transfer core. Upper and lower alignment layers are formed on surfaces of upper and lower substrates contacting a liquid crystal cell, respectively. A rubbing direction of the upper and lower alignment layers is at a predetermined angle with a gate line(11). The predetermined angle ranges from 40 to 50 degrees. The predetermined angle ranges from -40 to -50 degrees. The predetermined angle ranges from 130 to 140 degrees. The predetermined angle ranges from -130 to -140 degrees.

Description

OCB mode liquid crystal display device

1 is a plan view schematically showing a rubbing direction in an OCB mode liquid crystal display according to an embodiment of the present invention;

FIG. 2 is a plan view illustrating a form of a slit twisted domain in the OCB mode LCD of FIG. 1; FIG.

3A to 3C are plan views illustrating bend transitions in the OCB mode liquid crystal display of FIG. 1.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OCB mode liquid crystal display device, and more particularly, to an OCB mode liquid crystal display device for facilitating bend transition by the rubbing direction of the alignment layer.

Liquid crystal displays have been developed in place of CRTs based on the advantages of low weight, low voltage driving, and low power consumption. In particular, thin film transistor liquid crystal displays have various high resolution, large size, and color comparable to CRTs. Is being used.

Such a liquid crystal display has a structure in which a thin film transistor and an array substrate on which pixel electrodes are formed, and a color filter substrate on which a color filter layer and a counter electrode are formed are bonded together through a liquid crystal cell, and a liquid crystal used in a liquid crystal display generally has a twisted nema. Liquid crystals in a twisted nematic (TN) mode are mainly used.

However, the TN mode liquid crystal display device has a high image display contrast, but has a problem of low response speed and large viewing angle dependence. Therefore, an OCB (optically compensated bend) mode liquid crystal display device having a wide viewing angle and improved response speed has been proposed.

This OCB mode is implemented by transferring the molecular arrangement in the initial splay state to the molecular arrangement in the bend state, which is obtained by applying a high voltage to the liquid crystal cell having the molecular arrangement in the splay state.

However, such a transition from the splay state to the bend state is slow, and it is difficult to realize a uniform bend transition, so that a pattern capable of performing multi-orientation or acting as a transition nucleus on the pixel electrode is solved. Techniques for forming the same have been presented.

However, such multi-orientation or pattern formation on the pixel electrode complicates the entire process, resulting in a decrease in productivity, and a pattern formed on the pixel electrode must be covered by a black matrix or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an improved OCB mode liquid crystal display device which can promote the transition from the splay state to the bend state, while preventing the process simplification and lowering of the aperture ratio. The purpose.

The OCB mode liquid crystal display device of the present invention for achieving the above object, the liquid crystal cell having an initial splay orientation, the upper substrate provided on one side of the liquid crystal cell, the upper polarizing plate provided on one side of the upper substrate, and the upper substrate An upper compensation film interposed between the upper polarizing plate, a lower substrate provided on the other side of the liquid crystal cell, and provided with a pixel region defined by an intersection of a gate line and a data line, and provided on the other side of the lower substrate, and the upper polarizing plate A lower polarizing plate having an optical axis perpendicular to an optical axis of the lower polarizing plate and a lower compensation film interposed between the lower substrate and the lower polarizing plate, wherein upper and lower alignment layers are formed on respective surfaces of upper and lower substrates contacting the liquid crystal cell, and the upper and lower alignment layers Rubbing direction is preferably a direction forming a predetermined angle with the gate line.

Here, the predetermined angle is preferably within 40 ° ~ 50 °.

In addition, the predetermined angle is preferably within -40 ° ~ -50 °.

In addition, the predetermined angle is preferably within 130 ° ~ 140 °.

In addition, the predetermined angle is preferably within -130 ° ~ -140 °.

In addition, it is preferable that the rubbing direction of the upper and lower alignment layers forms 40 ° to 50 ° and -40 ° to -50 ° with the optical axis of the upper and lower polarizing plates, respectively.

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

First, the present invention is a technique of improving the transition rate by renewing the rubbing direction to the upper and lower substrates that the liquid crystal molecules in the splay state are slowly transferred to the liquid crystal molecules in the bend state, which is a conventional problem.

1 is a plan view schematically illustrating a rubbing direction of an OCB mode liquid crystal display according to an exemplary embodiment of the present invention.

Referring to the drawings, an OCB mode liquid crystal display device includes a liquid crystal cell (not shown) having an initial splay liquid crystal alignment, an upper substrate (not shown), an upper compensation film (not shown), and an upper polarizing plate (not shown) on one side of the liquid crystal cell. H) is provided sequentially.

On the other side of the liquid crystal cell, a gate line 11, a data line 12 intersecting the gate line 11, and a pixel region 13 defined by the intersection of the gate line 11 and the data line 12 are formed. A lower polarizer (not shown) having a lower substrate (not shown) and an optical axis perpendicular to the optical axes of the lower compensation film (not shown) and the upper polarizer are provided.

Since the structure of the OCB mode liquid crystal display described above is a structure of a general OCB mode liquid crystal display, a detailed description thereof will be omitted.

Upper and lower alignment layers (not shown) are formed on the surfaces of the lower and upper substrates in contact with the liquid crystal cell, respectively, and the upper and lower alignment layers are rubbed in the same direction.

Therefore, only the rubbing direction to the lower substrate will be described herein.

The rubbing direction to the lower alignment layer provided on the lower substrate is a rubbing process to form a predetermined angle with the gate line 11, the angle may be formed within 40 ~ 50 °, may be formed within 130 ~ 140 °, -40 Or less than -50 °, or -130 to -140 °.

That is, the lower alignment layer is rubbed in the diagonal direction of the pixel region 13 defined by the intersection of the gate line 11 and the data line 12.

The rubbing process of the lower alignment layer as described above is performed by using liquid crystal molecules provided in the space between the gate line 11 and the data line 12 and the pixel region 13 as the transition nucleus. 13) to quickly transfer the liquid crystal molecules in the splay state to the bend state.

In more detail, when a voltage is applied to the space between the gate line 11, the data line 12, and the pixel region 13, a noise field is inevitably caught.

When the liquid crystal molecules are aligned in the rubbing direction as described above in the space where the noise field is caught, the liquid crystal molecules oriented at a predetermined angle when a voltage is applied to the liquid crystal molecules in the direction of the noise field as shown in FIG. 2 by the influence of the noise field. As the molecules 15 rotate, the transition from the splay state to the bend state is accelerated, and the liquid crystal molecules 15 in the splay state inside the pixel region 13 are also rapidly bent under the influence of the accelerated transition rate. Will be transferred.

That is, in the region affected by the noise field, a lightly twisted domain having a somewhat twisted structure is formed according to the amount of voltage applied, and when the splay and twist orientations are mixed in this manner, the splayed and twisted orientations are oriented only in the splay state. Faster bend transitions occur than liquid crystal molecules.

3A to 3C, when a voltage is applied to the pixel region 13 as shown in FIG. 3A, the slitly twisted domain A is generated by the noise field at the corner of the pixel region 13. ) Is formed and the liquid crystal molecules in the splay state are transferred to the bend state in the inner direction as shown in FIG. 3B at a higher speed by the gliding twisted domain (A), and as time passes, the pixel as shown in FIG. The entire area will be transferred to the bend state.

According to the OCB mode liquid crystal display device having such a structure, the rubbing direction of the alignment layer is formed in a diagonal direction with respect to the pixel region, thereby forming a slitly twisted domain A in a region where a noise field is generated and using it as a transition nucleus. Therefore, the rate of transition from the splay to the bend can be improved without decreasing the aperture ratio.

Reference numeral 14 is a TFT.

 As described above, according to the OCB mode liquid crystal display device of the present invention, by forming the rubbing direction of the alignment layer in a diagonal direction with respect to the pixel area, a slitly twisted domain is formed in a region where a noise field is generated, and this is converted into a transition nucleus. By using it, it is possible to provide the effect of being able to improve the rate of liquid crystal molecular transition from the splay state to the bend state without lowering the aperture ratio.

It is to be understood that the invention is not limited to that described above and illustrated in the drawings, and that more modifications and variations are possible within the scope of the following claims.

Claims (6)

A liquid crystal cell having an initial splay orientation, an upper substrate provided on one side of the liquid crystal cell, an upper polarizing plate provided on one side of the upper substrate, an upper compensation film interposed between the upper substrate and the upper polarizing plate, and the other side of the liquid crystal cell A lower substrate having a pixel region defined by an intersection of a gate line and a data line, a lower polarizer having an optical axis disposed on the other side of the lower substrate, and having an optical axis perpendicular to an optical axis of the upper polarizer; In the OCB mode liquid crystal display including a lower compensation film interposed between the lower polarizer, An upper and lower alignment layer is formed on each surface of the upper and lower substrates in contact with the liquid crystal cell, the rubbing direction of the upper and lower alignment layer is a direction forming a predetermined angle with the gate line. The method of claim 1, The predetermined angle is an OCB mode liquid crystal display, characterized in that within 40 ° ~ 50 °. The method of claim 1, And the predetermined angle is within -40 ° to -50 °. The method of claim 1, The predetermined angle is an OCB mode liquid crystal display device, characterized in that within 130 ° ~ 140 °. The method of claim 1, And the predetermined angle is within -130 ° to -140 °. The method of claim 1, And a rubbing direction of the upper and lower alignment layers is in the range of 40 ° to 50 ° and -40 ° to -50 ° with the optical axis of the upper and lower polarizers, respectively.

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