KR100412124B1 - Apparatus for thin film transistor liquid crystal display - Google Patents

Abstract

The present invention relates to a thin film transistor liquid crystal display device, comprising: an upper substrate and a lower substrate facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes disposed on the lower substrate at predetermined intervals; A second common electrode disposed on the rear surface of the upper substrate so as to face the first common electrode; An insulating layer formed on the front surface of the lower substrate and the first common electrode and positioned between the first common electrode and having a plurality of curved concave-convex portions spaced by a predetermined distance on the lower substrate; And a pixel electrode disposed on the surface of the lower substrate between the uneven parts and the curved uneven parts positioned between the first common electrodes, and the viewing angle and the transmittance of the liquid crystal due to the vertical electric field and the lateral electric field. Improved, the curved electrode structure to implement a high electric field and a low liquid crystal cell gap is to improve the response speed of the liquid crystal.

Description

Thin Film Transistor Liquid Crystal Display {APPARATUS FOR THIN FILM TRANSISTOR LIQUID CRYSTAL DISPLAY}

The present invention relates to a thin film transistor liquid crystal display device, and more particularly, to a thin film transistor liquid crystal display device having both a twisted nematic mode and an in-plane switching mode in order to improve viewing angles and afterimage characteristics.

In general, liquid crystal displays (LCDs) have characteristics such as light weight, thinness, and low power consumption, so that they can be used for terminals or video devices of various information devices in place of cathode ray tubes (CRTs). It is used. In particular, a TFT-LCD equipped with a thin film transistor (TFT) as a switching element has excellent response characteristics and is suitable for high pixel numbers, thereby realizing high quality and large display devices.

Here, the conventional liquid crystal display device is a TWISTED NEMATIC (hereinafter referred to as TN) mode that is excellent in optical characteristics, clear black and white display, and excellent response characteristics of the liquid crystal.

In the TN mode liquid crystal display according to the related art, as illustrated in FIG. 1, a unit pixel is defined by crossing the gate line 13 and the data line 12, and a thin film transistor, which is a switching element, is formed at the intersection. 10) is arranged. The common electrode 15 is disposed on the lower substrate (not shown), and the pixel electrode 17 is disposed in the upper substrate (not shown) to overlap the common electrode 15. One end of the pixel electrode 17 is connected to a source electrode (unsigned) of the TFT 10, and a liquid crystal layer (not shown) is formed between the upper and lower substrates.

In the TN mode liquid crystal display, when a voltage is applied to both electrodes 15 and 21, liquid crystal molecules in the liquid crystal layer are arranged according to an electric field perpendicular to a substrate formed between the two electrodes to form a predetermined image.

However, the TN mode liquid crystal display according to the related art has the following problems as the liquid crystal molecules in the liquid crystal layer interposed between the upper and lower substrates have an elliptic rod shape.

In the TN mode liquid crystal display according to the related art, when an electric field is formed between the common electrode and the pixel electrode, the long axis of the liquid crystal molecules in the liquid crystal layer is parallel to the electric field (when the dielectric anisotropy of the liquid crystal is positive) or vertical (when the dielectric anisotropy of the liquid crystal is negative). Arranged to be twisted. At this time, since the liquid crystal as described above is rod-shaped, the refractive index anisotropy value when the panel of the liquid crystal display device is viewed from the front and the refractive index anisotropy value when viewed from the diagonal line are different from each other. Therefore, the conventional TN mode liquid crystal display has a problem that the viewing angle is very narrow. In order to solve the narrow viewing angle problem, an inplane switching (IPS) liquid crystal display device has been proposed. There was a problem of afterimage by back.

Accordingly, the thin film transistor liquid crystal display device according to the present invention is designed to solve the problems of the prior art, and an object of the present invention is a thin film transistor liquid crystal having a twisted nematic mode and an in-plane switching mode at the same time in order to improve the viewing angle and afterimage characteristic. In providing a display device.

1 is a plan view of a twisted nematic mode liquid crystal display according to the prior art.

2 is a plan view of a thin film transistor liquid crystal display according to a first embodiment of the present invention;

3 is a cross-sectional view of a thin film transistor liquid crystal display according to a first embodiment of the present invention.

4 is a cross-sectional view of a pixel portion of a thin film transistor liquid crystal display according to a first exemplary embodiment of the present invention.

5 is a plan view of a thin film transistor liquid crystal display according to a second exemplary embodiment of the present invention.

6 is a cross-sectional view of a pixel portion of a thin film transistor liquid crystal display according to a second exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

20; Lower substrate 21; Thin film transistor

22; Gate line 23; First common electrode

24; A gate insulating film 26; Active layer

28; Data line 28a; Source electrode

28b; Drain electrode 30; Shield

32; A second common electrode 34; Pixel electrode

36; Insulating film 38; Upper board

According to an aspect of the present invention, a thin film transistor liquid crystal display device includes: an upper substrate and a lower substrate facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes disposed on the lower substrate at predetermined intervals; A second common electrode disposed on the rear surface of the upper substrate so as to face the first common electrode; An insulating layer formed on the front surface of the lower substrate and the first common electrode and positioned between the first common electrode and having a plurality of curved concave-convex portions spaced by a predetermined distance on the lower substrate; And an insulating film including a curved concave and convex portion positioned between the first common electrode, and a pixel electrode disposed on a surface of the lower substrate between the concave and convex portions.

In addition, a thin film transistor liquid crystal display device according to a second embodiment of the present invention for achieving the above object, the upper substrate and the lower substrate facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes disposed on the lower substrate at predetermined intervals; A second common electrode disposed on the rear surface of the upper substrate so as to face the first common electrode; An insulating layer formed on a portion of the lower substrate and the first common electrode and positioned between the first common electrode and having a plurality of curved uneven parts spaced by a predetermined distance on the lower substrate; and between the first common electrode And an insulating film including a curved concave-convex portion positioned at the pixel electrode, and a pixel electrode disposed on the lower substrate surface between the concave-convex portions.

Hereinafter, the thin film transistor liquid crystal display according to the first and second embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a plan view of a thin film transistor liquid crystal display device according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view of a thin film transistor liquid crystal display device according to a first embodiment of the present invention, and FIG. 4 is a first embodiment of the present invention. 5 is a plan view of a thin film transistor liquid crystal display according to a second exemplary embodiment of the present invention, and FIG. 6 is a plan view of a thin film transistor liquid crystal display according to a second exemplary embodiment of the present invention. It is a section view.

In the thin film transistor liquid crystal display according to the first embodiment of the present invention, as shown in FIG. A thin film transistor 21 serving as a switching element, a plurality of insulating films 36, a pixel electrode 34 formed on the insulating film 36, and branches on both sides of the pixel electrode. The first common electrode 23 and the second common electrode (not shown) are included.

Meanwhile, as illustrated in FIG. 3, the thin film transistor liquid crystal display according to the present invention may be classified into a thin film transistor unit, a pixel unit, and a data unit.

First, as shown in FIG. 3, the thin film transistor unit includes a gate line 22, a gate insulating layer 24, an active layer 26, and source / drain electrodes 28a and 28b on the lower substrate 20. It is composed. In addition, the pixel portion may be divided into a plurality of via holes to partially expose the lower substrate 20, and may be formed on the insulating layer 36 having the curved concave-convex portion, and the upper portion of the insulating pixel electrode 34. The first common electrode 23 is formed on each of both sides of the pixel electrode 34, and although not shown in FIG. 3, the data line part includes a data line 28 and an insulating film 36. Here, the first common electrode 23 is entirely coated by the insulating film 36. On the other hand, the insulating film 36 is composed of a gate insulating film 24 and a protective film 30.

Here, the core technical idea of the present invention is that each of the curved pixel electrode 34 and the curved pixel electrode 34 formed on the plurality of divided insulating insulating film 36 is formed one by one, respectively A horizontal electric field (arrow) parallel to the substrates 20 and 38 applied to the liquid crystal by the first common electrode 23 and the pixel electrode 34 and the second common electrode 32 to the liquid crystal. Since the electric field is increased by the sum of the vertical electric fields perpendicular to the substrates 20 and 38, the optical characteristics such as the viewing angle and transmittance and the response speed of the liquid crystal are improved. .

The pixel portion of the thin film transistor liquid crystal display according to the first exemplary embodiment of the present invention includes an upper substrate 38 and a lower substrate 20 arranged to maintain a constant liquid crystal cell gap g, as shown in FIG. 4; A plurality of first common electrodes 23 disposed on the lower substrate 20 at predetermined intervals; A second common electrode 32 disposed on the rear surface of the upper substrate 38 so as to face the first common electrode 23; A plurality of curved shapes are formed on the front surface of the lower substrate 20 and the first common electrode 23, and are disposed between the first common electrode 23 and spaced apart by a predetermined interval on the lower substrate 20. An insulating film 36 having uneven portions; And an insulating film 36 having a curved concave-convex portion positioned between the first common electrode 23 and a pixel electrode 34 disposed on the surface of the lower substrate 20 between the concave-convex portions. Here, the first common electrode 23 is entirely coated by the insulating film 36.

In the curved insulating film 36, the angle θ between the inner surface and the lower substrate 20 is 10 to 90 degrees. In addition, the height h of the insulating film is about 3,000 to 20,000 mm based on the upper surface of the lower substrate 20.

Therefore, as described below, the common electrode 23 has a valley type (V-type) structure between the pixel electrode 34 formed on the curved insulating film 36 and the common electrode when voltage is applied. A and C portions are formed between the 23 and the pixel electrode 34 in which a horizontal electric field (arrow) is formed on the substrate 20.

Here, the lower width W1 of the curved insulating film 36 is formed not to be larger than the gap W2 between the divided insulating films 36, thereby facilitating the flow of liquid crystal during liquid crystal injection.

Meanwhile, a portion B between the second common electrode 32 formed on the upper substrate 38 and the pixel electrode 34 is formed in which a vertical electric field (arrow) perpendicular to the substrate 38 is formed. Accordingly, in the thin film transistor liquid crystal display device according to the present invention, a composite electric field is formed which is a sum of a horizontal electric field and a vertical electric field. It improves the transmittance of and serves to improve the response speed of the liquid crystal.

The distance l between the first common electrode 23 and the pixel electrode 34 is 2 to 15 μm, and the liquid crystal cell gap g between the lower substrate 20 and the upper substrate 38 is the height of the insulating film. h) up to 6 μm. In addition, since the insulating film 36 is partially removed from the lower substrate 20, deterioration due to electric field concentration on the insulating film 36 is reduced.

Meanwhile, in the thin film transistor liquid crystal display according to the second exemplary embodiment of the present invention, as shown in FIG. The thin film transistor 41 serving as a switching element disposed in the formed portion, the insulating film 56 divided into a plurality, the pixel electrode 54 formed on the insulating film 56, and the branches on both sides of the pixel electrode, respectively. The branch includes a first common electrode 43 and a second common electrode (not shown).

On the other hand, since the thin film transistor liquid crystal display according to the second embodiment of the present invention differs only in the structure of the insulating film 56 and the first common electrode 43 formed on the lower substrate 40, the description here will be omitted. Omit.

As illustrated in FIG. 6, the pixel portion of the thin film transistor liquid crystal display according to the second exemplary embodiment of the present invention includes: an upper substrate 58 and a lower substrate 40 facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes 43 disposed on the lower substrate 40 at predetermined intervals; A second common electrode 52 disposed on the rear surface of the upper substrate 58 so as to face the first common electrode 43; A plurality of bends formed on a portion of an upper surface of the lower substrate 40 and the first common electrode 43 and positioned between the first common electrode 43 and spaced apart from each other by a predetermined interval on the lower substrate 40. An insulating film 56 having a type uneven portion; And an insulating film 56 including a curved concave and convex portion positioned between the first common electrode 43 and a pixel electrode 54 disposed on the surface of the lower substrate 40 between the concave and convex portions. . Here, only a part of the first common electrode 43 is coated by the insulating film 56.

As described above, in the portion where the horizontal electric field (arrow) is formed on both substrates 40 and 58, the insulating film on the first common electrode 43 is partially removed, thereby improving the afterimage characteristic due to the electric field concentration on the insulating film. It plays a role.

Various embodiments can be easily implemented as well as self-explanatory to those skilled in the art without departing from the principles and spirit of the present invention. Accordingly, the claims appended hereto are not limited to those already described above, and the following claims are intended to cover all of the novel and patented matters inherent in the invention, and are also common in the art to which the invention pertains. Includes all features that are processed evenly by the knowledgeable.

As described above, the thin film transistor liquid crystal display according to the present invention has the following effects.

In the present invention, the electric field applied to the liquid crystal molecules of the liquid crystal layer is a composite field of a vertical electric field perpendicular to the substrate and a horizontal electric field parallel to the substrate, the field of view of the liquid crystal due to weakening of the concentration of the electric field on the insulating film by minimizing the insulating film, capacitance symmetry, and the like. Permeability is improved.

In addition, the present invention implements a high electric field and a low liquid crystal cell gap with a curved electrode structure to improve the response speed of the liquid crystal.

Claims (12)

An upper substrate and a lower substrate facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes disposed on the lower substrate at predetermined intervals; A second common electrode disposed on the rear surface of the upper substrate so as to face the first common electrode; An insulating film formed on the lower substrate between the lower substrate, the front surface of the first common electrode and the first common electrode, and having a plurality of curved concave-convex portions spaced by a predetermined interval; And And a pixel electrode disposed on the lower substrate surface between the uneven parts including the curved uneven parts of the insulating layer positioned between the first common electrodes. The method of claim 1, The height of the curved concave-convex portion of the insulating film is characterized in that the thin film transistor liquid crystal display device. The method of claim 1, And the inclination angle of one side of the curved concave-convex portion of the insulating layer and the lower substrate is 10 to 90 degrees. The method of claim 1, A thin film transistor liquid crystal display device, characterized in that the width of the lower portion of the curved concave-convex portion of the insulating film is smaller than the interval between the concave-convex portions. The method of claim 1, The thin film transistor liquid crystal display device wherein the first common electrode and the pixel electrode on the lower substrate have a spacing of 2 to 15 μm. The method of claim 1, The liquid crystal cell gap is a thin film transistor, characterized in that the maximum 6㎛. An upper substrate and a lower substrate facing each other to maintain a constant liquid crystal cell gap; A plurality of first common electrodes disposed on the lower substrate at predetermined intervals; A second common electrode disposed on the rear surface of the upper substrate so as to face the first common electrode; An insulating film formed on a portion of the upper surface of the lower substrate and the first common electrode and the lower substrate between the first common electrode and having a plurality of curved concave-convex portions spaced by a predetermined interval; And And a pixel electrode disposed on a surface of the lower substrate between the uneven parts including the curved uneven parts of the insulating layer positioned between the first common electrodes. The method of claim 7, wherein The height of the curved concave-convex portion of the insulating film is characterized in that the thin film transistor liquid crystal display device. The method of claim 7, wherein And the inclination angle of one side of the curved concave-convex portion of the insulating layer and the lower substrate is 10 to 90 degrees. The method of claim 7, wherein A thin film transistor liquid crystal display device, characterized in that the width of the lower portion of the curved concave-convex portion of the insulating film is smaller than the interval between the concave-convex portions. The method of claim 7, wherein The thin film transistor liquid crystal display device wherein the first common electrode and the pixel electrode on the lower substrate have a spacing of 2 to 15 μm. The method of claim 7, wherein The liquid crystal cell gap is a thin film transistor, characterized in that the maximum 6㎛.