KR100623443B1 - Multi-Domain Liquid Crystal Display Device - Google Patents

Abstract

The present invention relates to a liquid crystal display element having a high aperture ratio.

A multi-domain liquid crystal display device according to the present invention includes a data line to which a data signal is supplied, a pixel electrode for driving the liquid crystal, a gate line formed to intersect with the data line, a gate line formed at an intersection of the gate line and the data line, An auxiliary electrode line formed on the same plane as the gate line and overlapping the data line and the pixel electrode in the longitudinal direction to control the alignment direction of the liquid crystal by a common voltage signal; An organic insulating layer formed between the subsidiary electrode line and the data line to isolate the subsidiary electrode line from the data line, and a protective layer formed between the data line and the pixel electrode to isolate the data line from the pixel electrode.

According to the present invention, in the multi-domain liquid crystal display device according to the present invention, the data line and the counter electrode line overlap each other with the organic insulating film interposed therebetween, and the pixel area can be widened by the overlapping portion.

Description

[0001] The present invention relates to a multi-domain liquid crystal display device,             

1 is a plan view showing a conventional multi-domain liquid crystal display device.

Fig. 2 is a cross-sectional view taken along the line "A-A" in Fig. 1;

3 is a cross-sectional view taken along the line "B-B" in Fig. 1. Fig.

4 is a plan view showing a multi-domain liquid crystal display device according to an embodiment of the present invention.

5 is a cross-sectional view taken along the line "C-C" in Fig. 4. Fig.

Description of the Related Art

1: gate insulating film 2, 32: data line

3, 33: protective film 4: drain electrode

5,35: auxiliary electrode lines 6,36: pixel electrode

7n, 7n-1: Gate line 8: Drain contact

9: source electrode 10: TFT

11: gate electrode 13: auxiliary capacitor

14: auxiliary capacitor contact 31: organic insulating film

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having an increased aperture ratio.

A liquid crystal display device has advantages of small size, thinness and low power consumption, but is a flat panel display device having a disadvantage that the viewing angle is narrow. Such a liquid crystal display device is used in a notebook PC, office automation equipment, audio / video equipment, and the like. Particularly, an active matrix type liquid crystal display device using a thin film transistor (hereinafter referred to as "TFT") as a switching element is suitable for displaying a dynamic image.

An active matrix type liquid crystal display device displays an image corresponding to a video signal such as a television signal in a pixel matrix (Picture Element Matrix or Pixel Matrix) where pixels are arranged at intersections of gate lines and data lines. Each of the pixels includes a liquid crystal cell that adjusts the amount of transmitted light according to the voltage level of the data signal from the data line. The TFT is provided at the intersection of the gate line and the data line and switches the data signal to be transmitted to the liquid crystal cell in response to the scan signal from the gate line.

In order to compensate for a narrow viewing angle of a liquid crystal display device, a method for adjusting the alignment directions of liquid crystals in different directions in each of sub-pixels (sub-pixels or sub-domains) divided into two or more in one pixel Has been proposed. Such a liquid crystal display device includes a multi-domain liquid crystal display element in which an auxiliary electrode line is provided around a pixel electrode.

1, a multi-domain liquid crystal display element having a pixel electrode 6 connected to the drain electrode 4 of the TFT 10 and a subsidiary electrode line 5 formed around the pixel electrode 6 Respectively. The gate lines 7n and 7n-1 and the data lines 2 are formed on the substrate so as to intersect with each other. The TFT 10 is connected to the pixel electrode 6 through the drain electrode 8 and the source electrode 9 connected to the gate line 7n, the source electrode 9 connected to the data line 2, And an electrode (4). An active layer (not shown) is formed between the gate electrode 11 and the source electrode 9 in the TFT 10. The pixel electrode 6 is made of ITO (Indium Tin Oxide) having a high light transmittance and is formed within the intersection of the gate lines 7n and 7n-1 and the data line 2. [ The pixel electrode 6 is connected to the drain electrode 4 of the TFT 10 via the drain contact 8 and to the auxiliary capacitor 13 via the auxiliary capacitor contact 14. The pixel electrode 6 generates a potential difference with a transparent electrode (not shown) formed on the upper glass substrate by the data signal supplied via the drain contact 8. [ At this time, the liquid crystal is rotated by dielectric anisotropy, and the light supplied via the pixel electrode 6 is transmitted to the upper glass substrate. The auxiliary capacitor 13 and the front end gate line 7n-1 are connected to the gate line 7n-1 by applying a voltage during the scanning period of the preceding gate line 7n-1 and discharging the voltage charged during the scanning period, And serves as an auxiliary capacitor (Cst) for preventing the voltage variation of the pixel electrode (6). The subsidiary electrode line 5 generates a potential difference with the transparent electrode in the scanning period in which data is supplied to the pixel to adjust the alignment direction of the liquid crystal. The subsidiary electrode line 5 is supplied with a common voltage Vcom from an external common voltage generating circuit.

A structure and a manufacturing method of such a multi-domain liquid crystal display device will be described in detail with reference to FIGS. 1 and 2. FIG. 1 and 2, a gate material (a metal such as Mo, Al, Cr) is deposited on a lower glass substrate, and then patterned by photolithography. The patterned gate material layer becomes the gate lines 7n and 7n-1 and the gate electrode 11 of the TFT 10. [ A gate insulating material such as SiNx is entirely deposited on the lower glass substrate including the gate lines 7n and 7n-1, and amorphous silicon such as a-Si and n + a-Si are successively deposited on the gate insulating material. These gate insulating materials, a-Si and n + a-Si are patterned by photolithography to become the gate insulating film 1, the active layer and the n + layer, respectively. Metal materials such as Cr and Mo are deposited on the n + layer and the gate insulating film 1, and patterned. The patterned metal material layer becomes the data line 2, the auxiliary capacitor 13, the source electrode 9 and the drain electrode 4 of the TFT 10. The auxiliary capacitor 13 and the gate line 7n-1 at the front end serve as an auxiliary capacitor Cst with the gate insulating film 1 interposed therebetween as shown in FIG. The n + layer between the source electrode 9 and the drain electrode 4 patterned in the TFT 10 is removed. SiNx is entirely deposited on the lower glass substrate by CVD (Chemical Vapor Deposition) including the active layer exposed by the etching of the n + layer. In the protective film 3, the end pads of the data line 2 and the gate lines 7 and 7n-1, the drain electrode 4 of the TFT 10 and the upper side of the auxiliary capacitor 13, . After the contact hole forming step, ITO is deposited on the protective film 3 by sputtering and then patterned. The patterned ITO layer becomes the pixel electrode 6 and the subsidiary electrode line 5. On the other hand, the auxiliary electrode line 5 may be formed of a metal material differently from the pixel electrode 6. In this case, a mask is formed on the protective film 3 other than the auxiliary electrode line 5, and then a metal material is deposited to form the auxiliary electrode line 5.

However, in the conventional multi-domain liquid crystal display device, the number of the auxiliary electrode lines 5 must be formed separately from the data lines 2, and the pixel area is reduced, resulting in a small aperture ratio. Since the pixel is longer in the vertical direction than in the horizontal direction, the reduction of the aperture ratio in the vertical direction rather than the reduction of the aperture ratio in the horizontal direction significantly degrades the display quality. An inorganic material such as SiNx having a dielectric constant of about 6.7 is used as the material of the conventional protective film 3. The data line 2 and the subsidiary electrode line 5 are formed on the substrate so that coupling does not occur. Spacing. Accordingly, the aperture ratio in the longitudinal direction of the pixel is necessarily reduced by the area occupied by the data line 2 and the auxiliary electrode line 5. In addition, since a black matrix formed on the upper glass substrate overlaps the pixels at the left and right ends and the upper and lower ends of the pixel electrode 6 by about 5 mu m in order to block the leaked pixel light region, As the area is reduced, the aperture ratio is further reduced.

Accordingly, it is an object of the present invention to provide a multi-domain liquid crystal display device having an increased aperture ratio.

In order to achieve the above objects, a multi-domain liquid crystal display device according to the present invention includes a data line to which a data signal is supplied, a pixel electrode for driving the liquid crystal, a gate line formed so as to intersect with the data line, A switching element connected to the pixel electrode and formed on the same plane as the gate line and overlapped in the longitudinal direction of the data line and the pixel electrode, An organic insulating layer formed between the sub-electrode lines and the data lines to insulate the sub-electrode lines from the data lines; and a light-emitting layer formed between the data lines and the pixel electrodes, And a protective film formed to isolate the data line from the pixel electrode Being characterized in that the data line and the circulation line electrode are overlapped across the organic insulating film.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 4 and 5. FIG.

4 is a plan view of a multi-domain liquid crystal display device according to an embodiment of the present invention.

4, a multi-domain liquid crystal display device according to the present invention includes data lines 32 and gate lines 7n and 7n-1, data lines 32 and gate lines 7n and 7n-1 A pixel electrode 36 formed in the pixel region between the data lines 32 and the pixel electrodes 36 and a complementary electrode line 36 formed on the same plane as the gate lines 7n and 7n- 35). The TFT 10 is connected to the pixel electrode 36 via the gate electrode 11 connected to the gate lines 7n and 7n-1, the source electrode 9 connected to the data line 32 and the drain contact 8, And a drain electrode 4 connected to the drain electrode 4. In addition, an active layer is formed between the gate electrode 11 and the source electrode 9 in the TFT 10. The pixel electrode 36 is made of ITO having a high light transmittance and is formed within the intersection of the gate lines 7n and 7n-1 and the data line 32. [ The pixel electrode 36 is connected to the drain electrode 4 of the TFT 10 via the drain contact 8 and overlaps the front end gate line 7n-1. The pixel electrode 36 generates a potential difference with the transparent electrode formed on the upper glass substrate by the data signal supplied via the drain contact 8. At this time, the liquid crystal is rotated by dielectric anisotropy, and the light supplied via the pixel electrode 36 is transmitted to the upper glass substrate. The auxiliary electrode line 35 is disposed around the pixel electrode 36 to generate a potential difference with the pixel electrode 36 by a common voltage Vcom supplied during a scanning period in which data is supplied to the pixel to adjust the alignment direction of the liquid crystal . This subsidiary electrode line 35 is formed on the same plane as the gate lines 7n and 7n-1 and overlaps the data line 32 and the pixel electrode 36 with an organic insulating film interposed therebetween. Accordingly, the length of the pixel electrode 35 in the width direction is increased by at least the width in which the subsidiary electrode line 35 overlaps the data line 32. The overlapped portion between the auxiliary electrode line 35 and the pixel electrode 36 serves also as an auxiliary capacitor Cst for preventing the voltage fluctuation of the pixel electrode 36 and thus the capacitance of the auxiliary capacitor Cst is increased. Similarly to the gate lines 7n and 7n-1, when the subsidiary electrode line 35 is made of a metal material, the subsidiary electrode line 35 also serves as a black matrix for blocking a region in which inter-pixel light leaks. In this case, a separate black matrix is not necessary.

The structure and manufacturing method of such a multi-domain liquid crystal display device are as follows. 4 and 5, a metal material (metal such as Mo, Al, Cr) is deposited on a lower glass substrate, and then patterned by photolithography. The patterned metal material layer becomes the gate lines 7n and 7n-1, the gate electrode 11 of the TFT 10 and the subsidiary electrode line 35. [ The auxiliary electrode line 35 is made of a metal having a high light-blocking rate, and thus serves also as a black matrix. An organic material having a low dielectric constant is coated on the lower glass substrate including the gate lines 7n and 7n-1 and the auxiliary electrode line 35 by spin coating and then an amorphous silicon such as a-Si and an n + a-Si is continuously deposited. These organic materials, a-Si and n + a-Si are patterned to become the organic insulating film 31, the active layer and the n + layer, respectively. The organic insulating film 31 serves as a gate insulating film. Metal materials such as Cr and Mo are deposited on the n + layer and the organic insulating film 31, and then patterned. The patterned metal material layer becomes the data line 32, the source electrode 9 and the drain electrode 4 of the TFT 10. Here, the data line 32 is patterned on the organic insulating film 31 so as to overlap the subsidiary electrode line 35. The n + layer between the source electrode 9 and the drain electrode 4 patterned in the TFT 10 is removed. SiNx is deposited on the lower glass substrate by CVD, including the active layer exposed by the etching of the n + layer. A contact hole is formed in the protective film 33 above the drain electrode 4 of the TFT 10 and the end pad of the data line and the gate line. On the protective film 33, ITO is deposited by sputtering and then patterned. The patterned ITO layer becomes the pixel electrode 36. [ Here, the left and right end portions of the pixel electrode 36 are partially overlapped with the subsidiary electrode line 35 with the organic insulating film 31 and the protective film 33 interposed therebetween.

As described above, when the organic material is used as the gate insulating film, the data line 32 and the pixel electrode 36 may overlap with the auxiliary electrode line 35. This is because even though the data line 32 and the counter electrode line 35 overlap each other with the organic insulating film 31 interposed therebetween, the organic insulating film 31 can be thickly laminated and the dielectric constant of the organic insulating film 31 is low. And the data line 32 or between the subsidiary electrode line 35 and the pixel electrode 36. In this case, When the data line 32 and the pixel electrode 36 are overlapped with the auxiliary electrode line 35 in this way, the area of the pixel electrode 36 can be widened by the overlapping area, and the aperture ratio is increased.

As described above, in the multi-domain liquid crystal display device according to the present invention, the data line and the counter electrode line are overlapped with each other with the organic insulating film interposed therebetween, and the pixel area can be widened by the overlapped portion. In the multi-domain liquid crystal display device according to the present invention, an auxiliary electrode line is formed of a metal having a high light blocking rate at the boundary between pixels. Accordingly, the subsidiary electrode line also serves as a black matrix for preventing a leaked region of light between pixels, so that a separate black matrix is not required.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (4)

A data line to which a data signal is supplied, A pixel electrode for driving the liquid crystal, A gate line formed to cross the data line, A switching element formed at an intersection of the gate line and the data line and connected to the pixel electrode, A counter electrode line formed on the same plane as the gate line and overlapped with the data line in the longitudinal direction of the pixel electrode to generate a potential difference with the pixel electrode by a common voltage signal, An organic insulating layer formed between the subsidiary electrode line and the data line to isolate the subsidiary electrode line from the data line, And a protective film formed between the data line and the pixel electrode to insulate the data line from the pixel electrode, Wherein the data line and the counter electrode line overlap each other with the organic insulating film interposed therebetween. The method according to claim 1, Wherein the auxiliary electrode line is made of a metal material. The method according to claim 1, Wherein the auxiliary electrode line is formed to capture the periphery of the pixel electrode. The method according to claim 1, And the pixel electrode is formed to overlap the data line.

Images