CN102540535B - MVA liquid crystal display device - Google Patents

Abstract

The present invention provides an MVA pixel structure and a liquid crystal display device containing the MVA pixel structure. The MVA pixel structure is arranged on a substrate, which includes: at least two transparent conductive blocks, and a gap between the transparent conductive block and the substrate An insulating layer is provided, and the insulating layer has a first via hole, and the transparent conductive blocks are electrically connected through the first via hole with a conductive material. The domains of the MVA pixel structure provided by the present invention lead the potential to each transparent conductive (ITO) block through the conductive material through the via hole, which eliminates the metastable domain, and then eliminates the display unevenness caused by pressing and electric field, Domain stabilization is finally achieved. In addition, using the conductive material to form a storage capacitor can increase the aperture ratio of the pixel.

Description

A kind of MVA liquid crystal display device

field of invention

The invention relates to an MVA liquid crystal display device.

Background technique

Liquid crystal display devices (LCDs) have been widely used in various terminal display devices of large, medium and small sizes due to their light weight, small volume, and thin thickness. At present, the performance requirements of the market for liquid crystal display devices are developing toward characteristics such as high contrast, high brightness, low color shift, fast response, and wide viewing angle. At present, there are three main ways to meet the requirements of wide viewing angle: twisted nematic liquid crystal (TN) coupled with wide viewing angle film (WVF) liquid crystal display device, in-plane switching mode (IPS) liquid crystal display device, multi-domain vertical alignment ( MVA, multi-domain vertical) liquid crystal display device. Among them, the MVA mode liquid crystal display device has become the mainstream liquid crystal display device in the market due to its superiority in mass production and display characteristics.

In the MVA liquid crystal display device, when the voltage is turned off, that is, when the potential difference between the pixel cable electrode and the opposite electrode (also called the common electrode) is 0, the liquid crystal molecules are aligned vertically relative to the substrate plane, and when the voltage is maximum, Oriented parallel to the plane of the substrate. In addition, in the MVA type liquid crystal display device, black display is performed when the voltage is off, and white display is performed when the voltage is maximum.

Moreover, in order to improve the viewing angle characteristic, in the liquid crystal display device of the MVA system, the alignment division technique (multi-domain) of a liquid crystal molecule is combined in many cases. The alignment segmentation technique refers to a technique of dividing the liquid crystal layer into small regions, and changing the tilt direction of the liquid crystal molecules in each small region when they are aligned according to the voltage. That is, through control, the liquid crystal molecules are tilted to the right in a certain area, and tilted to the left in other areas. Thereby, the light intensity of the entire screen can be averaged, and the color change depending on the viewing angle can be significantly suppressed. The principle of the aforementioned orientation segmentation technology is that, for example, when the voltage is turned off, the orientation of the liquid crystal molecules at the boundary of each small area is not perpendicular to the plane of the substrate, but is in a state of inclination to a certain direction.

Vertically aligned (VA) liquid crystal molecules are vertically arranged in the liquid crystal layer in the liquid crystal cell relying on the surface riveting energy of the alignment film layer. When an electric field is applied to the ITO plates on both sides, the liquid crystal molecules will be deflected under the action of the electric field, and the optical path difference will be generated in conjunction with the settings of the polarizer and the backlight source, and the display can be realized by this. The main advantages of the MVA mode are high contrast and wide viewing angles.

In the current MVA display mode, the dislocation of domain distribution after pressing is an urgent problem to be solved. This dislocation of domain distribution occurs due to the change of metastable domains from the black state to the white state. The metastable domain is due to the disordered distribution of the fringe field, and mainly exists in the connection part of the transparent conductive block (ITO). The push mura can be seen as the dislocation of the domain distribution after the external force is applied. This will also cause image sticking (image stick) caused by non-common electrode dc residue to a certain extent. Currently, the usual MVA pixel structure is that the transparent conductive blocks of each domain are interconnected. This causes the problem of domain distribution misalignment. The usual solution is to use circular polarizers so that the metastable domains are not visible to the human eye. FIG. 1 is a schematic diagram of a MVA mode pixel structure in the prior art. 101 is a transparent conductive block (ITO), which is composed of three transparent conductive blocks (ITO) 101a, 101b, 101c and a connecting transparent conductive block 104 between the three conductive blocks; 102 is a protrusion (rib) on the side of the color filter ); 103 is the via hole and the storage capacitor area. The three transparent conductive blocks (ITO) 101a, 101b, 101c correspondingly form three domains, and there is a connected transparent conductive block (ITO) 104 between each domain, thus forming a metastable domain. When pressing, the dislocation of domain distribution will be formed, which will eventually cause push mura and image sticking.

Contents of the invention

The technical problem to be solved by the present invention is that the MVA pixel structure in the prior art has a metastable domain.

The inventive idea of the present invention is to remove the connecting parts between multiple ITO blocks in the pixel in the prior art and on the same layer as the multiple ITO blocks; multiple ITO blocks can be independent of each other on the same layer, but through The vias in the underlying insulating layer are point-connected with conductive material; this eliminates the metastable domain problem of prior art MVA pixel structures.

In order to solve the above-mentioned technical problems, the present invention provides an MVA liquid crystal display device, comprising a lower substrate, an upper substrate facing the lower substrate, and a liquid crystal layer sandwiched between the lower substrate and the upper substrate;

The MVA liquid crystal display device also includes an MVA pixel structure arranged on the lower substrate, the MVA pixel includes: at least two transparent conductive blocks, an insulating layer is arranged between the transparent conductive blocks and the substrate, and the The insulating layer has a first via hole, and the transparent conductive blocks are electrically connected through the first via hole with a conductive material; the side of the upper substrate facing the liquid crystal layer is provided with a color filter and a protrusion arranged on the color filter; the projection of the protrusion in a direction perpendicular to the upper substrate is circular.

As a preferred implementation manner, the insulating layer includes a gate insulating layer and a passivation layer. The MVA pixel structure further includes a thin film transistor as a pixel switch, the first via hole penetrates through the passivation layer, the conductive material is a source metal, and the source metal and the material of the source of the thin film transistor same and in the same layer.

For this preferred embodiment, the source/drain of the thin film transistor can be connected to the transparent conductive block through the first via hole; it can also be connected to the transparent conductive block through another separate via hole; directly connected to the conductive material.

Further, the MVA pixel structure also includes a common electrode that overlaps with the conductive material to generate a storage capacitor; in this way, the conductive material is used to form the storage capacitor, and it is not necessary to prepare it separately or only need to prepare a smaller storage capacitor, which improves the The opening rate. The gap regions between adjacent transparent conductive blocks can also be used to generate storage capacitors to further increase the aperture ratio.

As another preferred implementation manner, the insulating layer includes a gate insulating layer and a passivation layer. The MVA pixel structure further includes a thin film transistor as a pixel switch, the first via hole penetrates the passivation layer and the gate insulating layer, the conductive material is a gate metal, and the gate metal and the gate insulation layer The materials of the gates of the thin film transistors are the same and are in the same layer.

For this preferred embodiment, the source/drain of the thin film transistor can be connected to the transparent conductive block through the first via hole; it can also be connected to the transparent conductive block through another separate via hole; or the The source/drain of the thin film transistor may also be connected to the conductive material through another separate second via hole.

Compared with the prior art, the advantages and beneficial effects of the MVA liquid crystal display device of the present invention are: between the domains and the domains, the potential is led to each domain through a conductive material (such as the source metal or gate metal of the thin film transistor). The ITO block eliminates the metastable domain, and then eliminates the display unevenness caused by pressing and electric field, and finally realizes domain stability. In addition, using the conductive material to form a storage capacitor can increase the aperture ratio of the pixel.

Description of drawings

The drawings illustrate the embodiments of the invention and, together with the description, serve to explain the principles of the invention. Through the following detailed description in conjunction with the accompanying drawings, you can more clearly understand the purpose, advantages and features of the present invention, wherein:

FIG. 1 is a schematic diagram of an MVA pixel structure in the prior art;

FIG. 2 is a schematic diagram of the MVA pixel structure in Embodiment 1 of the present invention;

Fig. 3 is a schematic cross-sectional view of AA' of Fig. 2;

Fig. 4 is the BB ' sectional schematic diagram of Fig. 2;

FIG. 5 is a schematic diagram of the MVA pixel structure according to Embodiment 2 of the present invention;

Fig. 6 is a schematic cross-sectional view of AA' of Fig. 5;

Fig. 7 is a schematic cross-sectional view of BB' of Fig. 5;

FIG. 8 is a schematic diagram of the structure of an MVA pixel according to Embodiment 3 of the present invention;

Fig. 9 is a schematic cross-sectional view of AA' of Fig. 8;

Fig. 10 is a schematic cross-sectional view of BB' of Fig. 8;

FIG. 11 is a schematic diagram of the structure of an MVA pixel according to Embodiment 4 of the present invention;

Fig. 12 is a schematic cross-sectional view of AA' of Fig. 11;

Fig. 13 is a schematic cross-sectional view of BB' of Fig. 11;

FIG. 14 is a schematic diagram of the MVA pixel structure of an embodiment provided by the present invention with two transparent conductive blocks.

Detailed ways

In order to describe the technical contents and structural features of the present invention in detail, the following will be described in detail in conjunction with the embodiments and accompanying drawings.

Example 1

Referring to Figures 2 and 3, in Embodiment 1, the MVA pixel structure of the present invention is arranged on a lower substrate (not shown in the figure), and an upper substrate 210 is arranged on the lower substrate; between the lower substrate and the upper substrate 210 A liquid crystal layer 213 is sandwiched between them. A side of the upper substrate 210 facing the liquid crystal layer 213 is provided with a color filter (not shown in the figure) and a protrusion 202 disposed on the color filter.

The pixel electrode of each MVA pixel includes three transparent conductive blocks 201 (ITO can be used), and one protrusion 202 is provided corresponding to each transparent conductive block 201 on the side of the color filter. In this way, the molecules of the liquid crystal layer 213 between each transparent conductive block 201 and its corresponding protrusion 202 exhibit different tendencies, forming domains.

An insulating layer 212 is disposed between the transparent conductive block 201 and the lower substrate. The insulating layer 212 has a via hole 204 . The transparent conductive blocks 201 are electrically connected with the conductive material 203 through the via hole 204 in the insulating layer 212 . In conjunction with Fig. 2 and Fig. 4, it can be clearly seen that there is no connecting part between the three transparent conductive blocks 201 in the same layer as the transparent conductive block 201, and they are independent from each other in the same layer; Conductive materials 203 located in different layers are electrically connected. Thus, the metastable state between domains can be eliminated.

As a preferred implementation manner, the via hole 204 corresponding to each transparent conductive block 201 is opposite to the protrusion 202 corresponding to the transparent conductive block 201 . As shown in FIGS. 2 and 3 , viewed from a direction perpendicular to the pixel plane, the via hole 204 and the protrusion 202 completely overlap each other. Doing so can save the aperture ratio. In fact, the via holes 204 and the protrusions 202 may not be directly opposite to each other, but in doing so, both the via holes 204 and the protrusions 202 will lose the aperture ratio in the direction perpendicular to the pixel plane, that is, the light transmission direction.

As a preferred implementation manner, the conductive material 203 may be a metal material.

Example 2

As shown in FIG. 5, the pixel area of each MVA pixel is defined by scan lines 206 and data lines 207; each MVA pixel has a thin film transistor (TFT) as a pixel switch. The thin film transistor (TFT) is disposed on the lower substrate 211, including a gate on the lower substrate, a gate insulating layer 208 on the gate, a polysilicon layer on the gate insulating layer 208, and a source on the polysilicon layer. The drain electrode and the passivation layer 209 on the source and drain electrodes. The gate of the thin film transistor (TFT) is connected to the scan line 206 , its drain/source is connected to the data line 207 , and its source/drain is electrically connected to the transparent conductive block 201 . Generally, the gate of the thin film transistor (TFT) is made of the same material as the scan line 206 and is in the same layer; the source and drain of the thin film transistor (TFT) are made of the same material as the data line 207 and are in the same layer.

As a preferred embodiment, Embodiment 2 is based on Embodiment 1. The insulating layer 212 includes a gate insulating layer 208 and a passivation layer 209; the via hole 204 runs through the gate insulating layer 208 and the passivation layer 209 (such as Figure 6, Figure 7). The conductive material 203 is located at the junction of the gate insulating layer 208 and the lower substrate 211 . The conductive material 203 can be selected from gate metal, that is, the conductive material 203 can be the same as the gate material of the thin film transistor (TFT) and be in the same layer; Finished in the same process, saving costs.

In Embodiment 2, the source/drain of the thin film transistor (TFT) is electrically connected to the transparent conductive block 201 in the following manner: the source/drain of the thin film transistor (TFT) is connected to the transparent conductive block through the via hole in the passivation layer 209. block 201, this via hole can be the same as the via hole 204, or a via hole can be opened in the area outside the via hole 204 in the passivation layer 209; or the source/drain of the thin film transistor (TFT) passes through the gate The via hole in the electrode insulating layer 208 is connected to the conductive material 203 , and the via hole can be the same as the via hole 204 , or another via hole can be opened in the area of the gate insulating layer 208 other than the via hole 204 .

Example 3

As shown in FIG. 8, the pixel area of each MVA pixel is defined by scan lines 206 and data lines 207; each MVA pixel has a thin film transistor (TFT) as a pixel switch. The thin film transistor (TFT) is disposed on the lower substrate 211, including a gate on the lower substrate, a gate insulating layer 208 on the gate, a polysilicon layer on the gate insulating layer 208, and a source on the polysilicon layer. The drain electrode and the passivation layer 209 on the source and drain electrodes. The gate of the thin film transistor (TFT) is connected to the scan line 206 , its drain/source is connected to the data line 207 , and its source/drain is electrically connected to the transparent conductive block 201 . Generally, the gate of the thin film transistor (TFT) is made of the same material as the scan line 206 and is in the same layer; the source and drain of the thin film transistor (TFT) are made of the same material as the data line 207 and are in the same layer.

As a preferred implementation, Example 3 is based on Example 1. The insulating layer 212 includes a gate insulating layer 208 and a passivation layer 209; The junction of the passivation layer 209 (as shown in FIG. 9 and FIG. 10 ). The conductive material 203 can be selected from source/drain metal, that is, the conductive material 203 can be the same as the source and drain materials of the thin film transistor (TFT) and be in the same layer; 207 can be completed in the same process, saving costs.

In Embodiment 3, the source/drain of the thin film transistor (TFT) is electrically connected to the transparent conductive block 201 in the following manner: the source/drain of the thin film transistor (TFT) is connected to the transparent conductive block through the via hole in the passivation layer 209. block 201, this via hole can be the same as the via hole 204, or a via hole can be opened in the area outside the via hole 204 in the passivation layer 209; or the source/drain of the thin film transistor (TFT) is directly connected to the conductive The material 203 is connected, since the conductive material 203 is in the same layer as the source/drain of the thin film transistor (TFT) and the data line 207, it is easier to directly connect the source/drain of the thin film transistor (TFT) to the conductive material 203.

Example 4

As shown in FIG. 11 , FIG. 12 and FIG. 13 , Embodiment 4 is based on Embodiment 3, adding a common electrode 205 at the junction of the gate insulating layer 208 and the lower substrate 211 . The common electrode 205 overlaps with the conductive material 203 in the direction of light transmission to form a storage capacitor. In this way, the overlapping of the common electrode 205 and the conductive material 203 is used to form a storage capacitor, and it is unnecessary to prepare a storage capacitor or only need to prepare a smaller storage capacitor, which saves the aperture ratio.

The common electrode 205 and the conductive material 203 may overlap partially or completely, which is set according to the size of the storage capacitor to be formed.

The common electrode 205 and the conductive material 203 may also overlap in the gap area between the transparent conductive blocks 201 to form a storage capacitor.

The common electrode 205 can be made of the same material as the gate of the thin film transistor (TFT) and the scanning line 206, so that the three are in the same layer and can be completed in the same process, which saves costs.

In Embodiments 1, 2, 3 and 4, the pixel electrode of each pixel has three transparent conductive blocks 201 . The number of transparent conductive blocks in the MVA pixel structure provided by the present invention can also be 2 (as shown in FIG. 14 ), or an integer number of 4, 5 or 6. The MVA pixel structure shown in FIG. 14 is a preferred embodiment of the present invention, and two transparent conductive blocks are used to form two liquid crystal domains. Such a design can minimize the storage capacitance, thereby increasing the aperture ratio. In a specific product design, if the storage capacitor is not large enough, the gap region 214 between two transparent conductive blocks can be used as a storage capacitor, that is, both the conductive material 203 and the common electrode 205 cover the region 214, and the two overlap in the region 214 form a storage capacitor.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. In the above-described embodiments, various modifications and changes are possible to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. An MVA liquid crystal display device, comprising a lower substrate, an upper substrate facing the lower substrate, and a liquid crystal layer sandwiched between the lower substrate and the upper substrate; The MVA liquid crystal display device also includes an MVA pixel structure arranged on the lower substrate, the MVA pixel structure includes: at least two transparent conductive blocks, an insulating layer is arranged between the transparent conductive blocks and the substrate, The insulating layer has a first via hole, and the transparent conductive blocks are electrically connected through the first via hole with a conductive material; The side of the upper substrate facing the liquid crystal layer is provided with a color filter and a protrusion arranged on the color filter; the projection of the protrusion in a direction perpendicular to the upper substrate is circular. 2. The MVA liquid crystal display device according to claim 1, wherein the insulating layer comprises a gate insulating layer and a passivation layer. 3. The MVA liquid crystal display device according to claim 2, wherein the MVA pixel structure further comprises a thin film transistor as a pixel switch, the first via hole penetrates the passivation layer, and the conductive material is Source/drain metal, the source/drain metal is the same material as the source and drain of the thin film transistor and is in the same layer. 4. The MVA liquid crystal display device according to claim 3, wherein the source/drain of the thin film transistor is connected to the transparent conductive block through the first via hole; or the source/drain of the thin film transistor The drain is directly connected to the conductive material. 5 . The MVA liquid crystal display device according to claim 3 , wherein the MVA pixel structure further comprises a common electrode overlapping with the conductive material to generate a storage capacitor. 6 . The MVA liquid crystal display device according to claim 5 , wherein a storage capacitor is formed in a gap region between adjacent transparent conductive blocks. 7. The MVA liquid crystal display device according to claim 2, wherein the MVA pixel structure further comprises a thin film transistor as a pixel switch, and the first via hole penetrates the passivation layer and is insulated from the gate layer, the conductive material is gate metal, and the gate metal is the same material as the gate of the thin film transistor and is in the same layer. 8. The MVA liquid crystal display device according to claim 7, wherein the source/drain of the thin film transistor is connected to the transparent conductive block through the first via hole; or the source/drain of the thin film transistor The drain is connected to the conductive material through the second via hole.