KR100466395B1 - Thin film transistor lcd - Google Patents

Abstract

The present invention discloses a thin film transistor liquid crystal display device capable of preventing the occurrence of color shift when displaying a liquid crystal display device. The present invention discloses an upper and lower substrate made of a transparent insulating substrate; A gate bus line disposed in one direction on the lower substrate; A data bus line vertically intersecting with the gate bus line to define a unit pixel area; A thin film transistor disposed on an area where the gate bus line and the data bus line cross each other; A plate-shaped first relative electrode disposed in parallel with the data bus line on the unit pixel area; A slit-type pixel electrode disposed to overlap with an insulating layer on the first relative electrode; An alignment layer applied to an inner surface of a lower substrate on which the pixel electrode is formed; A slit-type second relative electrode disposed on the upper substrate; An alignment layer applied to an inner surface of the upper substrate on which the slit-type second relative electrode is disposed; And a liquid crystal layer interposed between the upper and lower substrates, wherein the slit of the second relative electrode disposed on the upper substrate has a direction parallel to the gate bus line so as to intersect with the slit of the pixel electrode disposed on the lower substrate. .

Description

Thin Film Transistor Liquid Crystal Display {THIN FILM TRANSISTOR LCD}

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 a wide viewing angle by preventing color shift occurring in different viewing angle directions.

In general, in order to improve a narrow viewing angle in a twisted nematic (TN) mode liquid crystal display, an IPS (In-Plane Switching) mode liquid crystal display in which a counter electrode is disposed on a lower substrate has been developed.

The electrode structure of the IPS mode liquid crystal display device is a structure having a wide viewing angle because a horizontal electric field is generated by applying a counter electrode made of an opaque metal and a pixel electrode made of a transparent metal on a glass substrate.

However, since the IPS mode liquid crystal display uses an opaque metal as a counter electrode, the transmittance is low and the response speed is slow because the liquid crystals are arranged horizontally. Thus, in order to improve this, a VA (Vertical Aligment) mode for arranging the arrangement of liquid crystal molecules vertically has been proposed.

In this regard, the thin film transistor liquid crystal display according to the related art will be described with reference to FIG. 1.

1 is a view for explaining the liquid crystal array and electrode structure of the VA mode liquid crystal display according to the prior art.

In the thin film transistor liquid crystal display according to the related art, as illustrated in FIG. 1, a pixel electrode 1 made of ITO or IZO metal is disposed on a lower glass substrate 10a that is a transparent insulating substrate, and the pixel is disposed. On the electrode 1, the alignment film 4a which arranges a liquid crystal in the vertical direction is apply | coated.

Moreover, the plate-shaped counter electrode 3 is arrange | positioned on the upper glass substrate 10b, and the alignment film 4b which arranges a liquid crystal in the vertical direction is apply | coated on the counter electrode 3. The upper and lower glass substrates 4a and 4b having such a structure are bonded together with the liquid crystal interposed therebetween, and the liquid crystal molecules are arranged vertically.

The VA mode liquid crystal display having such a structure has a fast response when an electric field is applied, and has a wide viewing angle.

However, since the conventional VA mode liquid crystal display has a wide viewing angle, a process for varying the liquid crystal array is required, and thus, a large number of rubbing processes are required, resulting in a decrease in manufacturing yield and an increase in manufacturing cost. There is.

In addition, since the arrangement of the liquid crystal molecules has only a single direction, the IPS mode liquid crystal display device and the VA mode liquid crystal display device described above have a liquid crystal display in which the major and minor directions of the liquid crystal are different from the cell gap d depending on the polarization angle of light. Since the value of Δn is relatively different, there is a problem that a color shift occurs according to the viewing angle direction.

Accordingly, the present invention has been made to solve the above problems of the prior art, combining the advantages of the IPS mode and VA mode has a fast response time and high transmittance, and can remove the color shift phenomenon liquid crystal It is an object to provide a display device.

1 is a view for explaining a liquid crystal array and the electrode structure of a VA mode liquid crystal display according to the prior art.

2A is a plan view showing a pixel electrode structure of an FFS-VA mode liquid crystal display device according to the present invention;

2B is a plan view showing a counter electrode structure of an upper substrate of an FFS-VA mode liquid crystal display according to the present invention;

3 is a view for explaining the liquid crystal array and electrode structure of the FFS-VA mode liquid crystal display according to the present invention.

4A is a diagram for explaining an electric field application direction between upper and lower substrates according to the present invention;

4B is a view for explaining the direction of liquid crystal molecules according to the present invention.

Fig. 5A is a plan view showing a pixel electrode structure of another embodiment of the present invention.

5B is a plan view showing a counter electrode structure of an upper substrate of another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

16: pixel electrode 17: first relative electrode

19: second relative electrode 20a: upper glass substrate

20b: lower glass substrate 21: insulating film

24a, 24b: vertical alignment layer 25: liquid crystal molecules

The present invention for achieving the above object, the upper and lower substrates made of a transparent insulating substrate; A gate bus line disposed in one direction on the lower substrate; A data bus line vertically intersecting with the gate bus line to define a unit pixel area; A thin film transistor disposed on an area where the gate bus line and the data bus line cross each other; A plate-shaped first relative electrode disposed in parallel with the data bus line on the unit pixel area; A slit-type pixel electrode disposed to overlap with an insulating layer on the first relative electrode; An alignment layer applied to an inner surface of a lower substrate on which the pixel electrode is formed; A slit-type second relative electrode disposed on the upper substrate; An alignment layer applied to an inner surface of the upper substrate on which the slit-type second relative electrode is disposed; And a liquid crystal layer interposed between the upper and lower substrates, wherein the slit of the second relative electrode disposed on the upper substrate has a direction parallel to the gate bus line so as to intersect with the slit of the pixel electrode disposed on the lower substrate. It is done.

Here, the pixel electrode, the first relative electrode, and the second relative electrode are all transparent metals of ITO or IZO.

In addition, another embodiment of the present invention is the upper and lower substrates made of a transparent insulating substrate; A gate bus line disposed in one direction on the lower substrate; A data bus line vertically intersecting with the gate bus line to define a unit pixel area; A thin film transistor disposed on an area where the gate bus line and the data bus line cross each other; A plate-shaped first relative electrode disposed in parallel with the data bus line on the unit pixel area; A slit-type pixel electrode disposed to overlap with an insulating layer on the first relative electrode; An alignment layer applied to an inner surface of a lower substrate on which the pixel electrode is formed; A slit-type second relative electrode disposed on the upper substrate; An alignment layer applied to an inner surface of the upper substrate on which the slit-type second relative electrode is disposed; And a liquid crystal layer interposed between the upper and lower substrates, wherein the slit of the pixel electrode has a '>' shaped structure having a predetermined angle so as to be symmetrical with each other along a unit pixel central axis parallel to the gate bus line. The corresponding slit of the second relative electrode of the upper substrate has a '<' shaped structure intersecting with the slit of the pixel electrode.

According to the present invention, a color shift phenomenon can be prevented by combining liquid crystal molecules with various alignment directions by combining the electrode structure of the fringe field driving mode liquid crystal display with the counter electrode of the upper substrate of the VA mode liquid crystal display.

(Example)

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

2A is a plan view showing a pixel electrode structure of an FFS-VA mode liquid crystal display device according to the present invention, and FIG. 2B is a plan view showing a counter electrode structure of an upper substrate of an FFS-VA mode liquid crystal display device according to the present invention. .

In the liquid crystal display according to the exemplary embodiment of the present invention, as illustrated in FIG. 2A, a gate bus line 11 and a data bus line 13 are vertically intersected and arranged on a lower glass substrate (not shown). A thin film transistor 15 is disposed on the region where the pixel area is defined and the gate bus line 11 and the data bus line 13 cross each other.

In addition, a plate-shaped first relative electrode 17 is disposed in parallel with the data bus line 13 on the unit pixel region, and an insulating film is interposed between the first relative electrode 17 and a slit type. The pixel electrodes 16 are arranged to overlap.

The first relative electrode 17 and the pixel electrode 16 are made of ITO metal or IZO metal, which is a transparent metal, and the slits of the pixel electrode 16 are parallel to the data bus line 13. It is formed in the direction.

On the other hand, the counter electrode structure of the upper substrate of the FFS-VA mode liquid crystal display according to the present invention, as shown in Figure 2b, the upper glass substrate (not shown) to face the pixel electrode 16 shown in Figure 2a ), The slit type second relative electrode 19 is disposed.

In addition, the slits of the slit-type second relative electrode 19 are formed in a direction parallel to the gate bus line 11 so as to vertically cross the slits of the pixel electrode 16.

3 is a view for explaining the liquid crystal array and the electrode structure of the FFS-VA mode liquid crystal display according to the present invention, the plate-like first partner of the ITO metal on the lower glass substrate 20a of the transparent insulating substrate An electrode 17 is disposed, and a slit pixel electrode 16 is disposed on the first relative electrode 17 with an insulating film 21 therebetween. In addition, an alignment film 24a for arranging liquid crystals in a vertical direction is coated on the pixel electrode 16.

A slit-type second relative electrode 19 crossing the pixel electrode 16 is disposed on the upper glass substrate 20b, and an alignment layer for arranging liquid crystals in the vertical direction on the second relative electrode 19. 24b) is applied.

The upper and lower glass substrates 24a and 24b having such a structure are bonded together with the liquid crystal interposed therebetween. Here, the liquid crystal molecules are in a VA mode arranged vertically, and the electrode structure of the lower substrate 20a is a FFS (Fringe Field Switching) mode electrode structure.

In the thin film transistor liquid crystal display device having the above structure, the liquid crystal molecules are vertically arranged before the electric field is applied, and although not shown in the drawing, the long axis of the liquid crystal molecules is compensated by the phase compensation film to form a completely dark state. .

At this time, when a voltage is applied, preferably, the first relative electrode 17 and the second relative electrode 19 have an equipotential, and have a voltage difference from the pixel electrode 16. In the electrode to which the voltage is applied, an electric field is generated between the pixel electrode 16, the first relative electrode 17, and the second relative electrode 19, respectively, so that liquid crystal molecules are variously arranged up, down, left, and right, and color in any direction. It has a wide viewing angle where no shift occurs.

FIG. 4A is a view for explaining an electric field application direction between upper and lower substrates according to the present invention. As shown in FIG. 4A, the pixel substrate 16 and the first relative electrode 17 are the same as the electrode structure of the FFS mode in the lower substrate. A strong fringe field is formed in a direction parallel to the data bus line (not shown), and an electric field generated at is parallel to the gate bus line (not shown) between the second relative electrode 19. An electric field in the direction is formed. The other up and down electric fields thus formed allow the liquid crystal molecules to rotate in four directions of up, down, left, and right to widen the viewing angle.

4B is a view for explaining the direction of the liquid crystal molecules according to the present invention. As shown, the liquid crystal molecules are arranged in four directions about the vertical polarization axes (α, β) by the FFS-VA mode structure. Able to know.

FIG. 5A is a plan view illustrating a pixel electrode structure according to another exemplary embodiment of the present invention. As shown in FIG. 5A, a second electrode disposed on the pixel electrode 26 and the upper substrate has an electrode structure as described with reference to FIGS. 2A and 2B. The structure of the counter electrode 29 is changed and arranged.

Here, the pixel electrode 26 has a '>' shaped structure in which the pixel electrode 26 is vertically symmetrical at a predetermined angle with respect to the central axis of the unit pixel parallel to the gate bus line 11.

FIG. 5B is a plan view illustrating a counter electrode structure of an upper substrate according to another embodiment of the present invention. As shown in FIG. 5B, the structure of the second counter electrode 29 corresponding to the pixel electrode 26 illustrated in FIG. In order to intersect the pixel electrode 26, the pixel electrode 26 has a '<' shaped structure that is vertically symmetrical at a predetermined angle with respect to the central axis of the unit pixel region parallel to the gate bus line 11.

The above-described FFS-VA mode liquid crystal display has both a FFS mode electrode structure generating a strong fringe field and a VA mode structure in which the liquid crystal molecules are vertically arranged to give a fast response. Speed, low transmittance, and color shift can be eliminated.

As described above, the present invention combines the VA mode electrode structure in which the counter electrode is added to the upper substrate to the electrode structure of the fringe field driving mode liquid crystal display device to remove the color shift phenomenon by varying the alignment direction of the liquid crystal molecules. It works.

In addition, it is possible to obtain transmittance, high-speed response, and high contrast ratio in the display of the liquid crystal display.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

Claims (3)

Upper and lower substrates made of a transparent insulating substrate; A gate bus line disposed in one direction on the lower substrate; A data bus line vertically intersecting with the gate bus line to define a unit pixel area; A thin film transistor disposed on an area where the gate bus line and the data bus line cross each other; A plate-shaped first relative electrode disposed in parallel with the data bus line on the unit pixel area; A slit pixel electrode disposed to overlap with an insulating layer on the first relative electrode; An alignment layer applied to an inner surface of a lower substrate on which the pixel electrode is formed; A slit-type second relative electrode disposed on the upper substrate; An alignment layer applied to an inner surface of the upper substrate on which the slit-type second relative electrode is disposed; It is configured to include a liquid crystal layer interposed between the upper and lower substrates, And a slit of the second relative electrode disposed on the upper substrate is disposed in a direction parallel to the gate bus line so as to intersect with the slit of the pixel electrode disposed on the lower substrate. The method of claim 1, And the pixel electrode, the first relative electrode and the second relative electrode are all transparent metals of ITO or IZO. Upper and lower substrates made of a transparent insulating substrate; A gate bus line disposed in one direction on the lower substrate; A data bus line vertically intersecting with the gate bus line to define a unit pixel area; A thin film transistor disposed on an area where the gate bus line and the data bus line cross each other; A plate-shaped first relative electrode disposed in parallel with the data bus line on the unit pixel area; A slit pixel electrode disposed to overlap with an insulating layer on the first relative electrode; An alignment layer applied to an inner surface of a lower substrate on which the pixel electrode is formed; A slit-type second relative electrode disposed on the upper substrate; An alignment layer applied to an inner surface of the upper substrate on which the slit-type second relative electrode is disposed; It is configured to include a liquid crystal layer interposed between the upper and lower substrates, The slits of the pixel electrodes are disposed to be inclined at a predetermined angle so as to be symmetrical with each other along a unit pixel central axis parallel to the gate bus line, and the slits of the second relative electrodes of the upper substrate corresponding to the pixel electrodes are the pixel electrodes. The liquid crystal display device of claim 1, wherein the liquid crystal display is disposed to be inclined by a predetermined angle so as to be vertically symmetrical to intersect with the slits.