Active matrix substrate with pre-charge components and liquid crystal display panel thereof

This application claims the priority benefit of Taiwan application serial no. 96210364, filed on Jun. 26, 2007. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

1. Field of the Invention

The present invention is related to an active matrix substrate and a display panel, and more particularly to an active matrix substrate and a liquid crystal display (LCD) panel having pre-charge components.

2. Description of Related Art

Currently existing thin-film transistor liquid crystal displays (TFT-LCDs) can be generally classified into poly silicon TFT-LCDs and amorphous silicon TFT-LCDs. Among them, the amorphous silicon TFT-LCDs are commonly adopted by the general public for the advantages, such as a low manufacturing cost and a high yield. LCDs are developed toward having large size and high resolution, and therefore, within each frame time, the charging time assigned to each pixel unit becomes shorter and shorter. When an issue of insufficient charging happens to the pixel units, the display quality of LCDs would significantly worsen.

To solve the aforementioned problem, many driving methods have been provided successively, and one of the driving methods is utilizing a dual scan pulse technique to improve the display quality of LCDs. Such technique performs writing data to each pixel unit mainly via a pre-charge scan pulse and a charge scan pulse. Because of the pre-charge scan pulse, the charge scan signal can quickly charge the pixel units so as to improve the display quality and shorten the response time of LCDs.

However, since such dual scan pulse driving technique is more complicated, TFT-LCDs need to adopt complicated driving ICs so as to achieve both good display quality and fast response time. Therefore, manufacturing LCDs by the dual scan pulse technique requires a higher cost.

The present invention is to provide an active matrix substrate to mitigate the problem of insufficient charging its pixel units.

The present invention is to provide an active matrix substrate having a feature of pre-charging the pixel units.

The present invention is to provide a liquid crystal display (LCD) panel including the active matrix substrate to mitigate the problem of bad display contrast.

The present invention is to provide an LCD panel including the active matrix substrate to improve the display quality.

The present invention provides an active matrix substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of pixel units and a plurality of pre-charge components. The scan lines, data lines and pixel units are all disposed on the substrate. The pixel units are electrically connected with the corresponding scan lines and data lines, wherein each of the pixel units includes an active device and a pixel electrode. The active device is electrically connected with the scan line and the data line, and the pixel electrode is electrically connected with the active device. Each of the pre-charge components is electrically connected with one of the scan lines and two adjacent pixel electrodes controlled by the next scan line. When each of the pre-charge components is turned on via the scan line electrically connected therewith, the two adjacent pixel electrodes electrically connected with each of the pre-charge components have the same voltage level.

The present invention further provides an LCD panel including the active matrix substrate, an opposite substrate and a liquid crystal layer. The opposite substrate is disposed above the active matrix substrate, and the liquid crystal layer is disposed between the active matrix substrate and the opposite substrate.

The present invention further provides an active matrix substrate including a substrate, a plurality of scan lines, a plurality of data lines, a plurality of common lines and a plurality of pixel units. The scan lines, data lines, common lines and pixel units are all disposed on the substrate. The common lines are arranged between two adjacent scan lines. The pixel units are electrically connected with the corresponding scan lines and data lines, wherein each of the pixel units includes a pixel electrode, an active device and a pre-charge component. In each of the pixel units, the active device is electrically connected with the scan line, the data line and the pixel electrode corresponding to the pixel unit while each of the pre-charge components is electrically connected with the preceding scan line of the pixel unit, the common line and the pixel electrode. When each of the pre-charge components is turned on via the preceding scan line, a plurality of pixel electrodes electrically connected with each of the pre-charge components have the same voltage level as the common line.

The present invention moreover provides an LCD panel including the active matrix substrate, an opposite substrate and a liquid crystal layer. The opposite substrate is disposed above the active matrix substrate, and the liquid crystal layer is disposed between the active matrix substrate and the opposite substrate.

With the plurality of pre-charge components, the pixel units in the LCD panel of the present invention can be pre-charged before liquid crystal molecules are driven so as to mitigate the problem of insufficient charging of pixel units and bad display contrast. Meanwhile, the display quality of the LCD panels is enhanced. In addition, the driving method of the LCD panel of the present invention is simpler than the conventional technique.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, several embodiments accompanied with figures are described in detail below.

FIG. 1A is a schematic cross-sectional view of a liquid crystal display (LCD) panel according to the first embodiment of the present invention.

FIG. 1B is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel in FIG. 1A .

FIG. 2 is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel according to the second embodiment of the present invention.

FIG. 3A is a schematic cross-sectional view of the LCD panel according to the third embodiment of the present invention.

FIG. 3B is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel in FIG. 3A .

FIG. 4 is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel according to the forth embodiment of the present invention.

FIG. 1A is a schematic cross-sectional view of a liquid crystal display (LCD) panel according to the first embodiment of the present invention. FIG. 1B is a schematic circuit diagram illustrating of two adjacent pixel units on the same row of the LCD panel in FIG. 1A . Referring to both FIG. 1A and FIG. 1B , an LCD panel 100 a includes an opposite substrate 200 , an active matrix substrate 300 and a liquid crystal layer 400 . The opposite substrate 200 is disposed above the active matrix substrate 300 , and the liquid crystal layer 400 is disposed between the active matrix substrate 300 and the opposite substrate 200 .

The opposite substrate 200 is, for example, a color filter array substrate which may include a substrate 210 , a black matrix layer 220 a , a plurality of color filter patterns 220 b and a common electrode 230 . The black matrix layer 220 a and the plurality of color filter patterns 220 b are disposed on the substrate 210 , while the common electrode 230 is disposed on the black matrix layer 220 a and the color filter patterns 220 b.

The active matrix substrate 300 includes a substrate 310 , a plurality of scan lines 320 a and 320 b arranged in row direction (only two scan lines shown in FIG. 1B ), a plurality of data lines 330 a and 330 b arranged in column direction (only two data lines shown in FIG. 1B ), a plurality of pixel units 340 a and a plurality of pre-charge components 350 . The scan lines 320 a , 320 b and the data lines 330 a , 330 b cross to each other to define a pixel unit 340 a . The scan lines 320 a and 320 b , the data lines 330 a and 330 b and the pixel units 340 a are all disposed on the substrate 310 . The pixel units 340 a are electrically connected with the corresponding scan lines (e.g. the scan lines 320 a or 320 b ) and the corresponding data lines (e.g. the data lines 330 a or 330 b ) respectively.

Each of the pixel units 340 a includes an active device 342 and a pixel electrode 344 . In each of the pixel units 340 a , the active device 342 is electrically connected with the corresponding scan line 320 a (or 320 b ), data line 330 a (or 330 b ) and pixel electrode 344 (as shown in FIG. 1B ). The active device 342 is a thin-film transistor (TFT), for example, and a liquid crystal capacitor C LC can be formed by the pixel electrode 344 , the liquid crystal layer 400 and the common electrode 230 . When each of the pixel units 340 a is charged, an electric field can be generated so as to drive liquid crystal molecules between the common electrode 230 and the pixel electrode 344 .

Each of the pre-charge components 350 is electrically connected with one of the scan lines 320 a and two adjacent pixel electrodes 344 controlled by the next scan line 320 b (as shown in FIG. 1B ). In other words, from the perspective view of the pixel unit 340 a , the pre-charge component 350 is electrically connected with the preceding scan line 320 a and the pixel electrodes 344 that are controlled by scan line 320 b . The pre-charge component 350 can be a TFT having a gate 350 a , a drain 350 b and a source 350 c . The gate 350 a is electrically connected with the scan line 320 a , and the drain 350 b and the source 350 c are electrically connected with the two adjacent pixel electrodes 344 controlled by the next scan line 320 b respectively.

In the present embodiment, each of the pixel units 340 a can further include a storage capacitor 346 a electrically connected with the active device 342 via the pixel electrode 344 . In the present embodiment, the storage capacitors 346 a are capacitors on the scan lines 320 a . In other words, the storage capacitor 346 a can be formed on the scan line 320 a , that is, the storage capacitor 346 a can be formed by the preceding scan line 320 a and the pixel electrode 344 of the pixel unit 340 a . However, although only the storage capacitor 346 a formed on the scan line 320 a is shown in FIG. 1B , the storage capacitor 346 a of FIG. 1B is merely illustrated as an example and not intended to limit the present invention. In addition, the storage capacitor 346 a can be arranged in the structure of metal layer/insulator layer/indium tin oxide (ITO) layer (MII), or metal layer/insulator layer/metal layer (MIM).

A driving method of the LCD panel 100 a of the first embodiment will be described accompanied with FIG. 1B hereinafter. As for the driving method of the LCD panel 101 a of the present embodiment, first, the pixel units 340 a on the same row controlled by each of the scan lines (e.g. 320 a or 320 b ) are charged so as to drive the LCD panel 100 a . Herein, the pixel units 340 a can be charged via some methods, such as column inversion driving method, dot inversion driving method or other proper driving methods.

When the pixel unit 340 a controlled by one of the scan lines 320 a is charged, the pre-charge component 350 electrically connected with the scan line 320 a is turned on via the scan line 320 a . When the pre-charge component 350 is turned on, the two adjacent pixel electrodes 344 electrically connected with the pre-charge component 350 can be conducted to each other. Thus, the charges of the two adjacent pixel electrodes 344 are shared with each other and have the same voltage level, so that the effect of pre-charging the adjacent pixel electrodes 344 can be achieved. Therefore, the pixel unit 340 a controlled by the next scan line 320 b is pre-charged by the pre-charge component 350 . Once the pixel unit 340 a has been pre-charged, it can be quickly charged to drive the liquid crystal molecules corresponding to the pixel unit 340 a.

FIG. 2 is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel according to the second embodiment of the present invention. Referring to FIG. 2 , the present embodiment is similar to the first embodiment, and the main difference between the present embodiment and the first embodiment is that a LCD panel 100 b of the second embodiment includes a plurality of common lines 360 disposed on the substrate 310 and a storage capacitor 346 b disposed in each of the pixel units 340 b.

Specifically, each of the common lines 360 is arranged between two adjacent scan lines (e.g. between scan lines 320 a and 320 b ), and the storage capacitor 346 b disposed in each of the pixel units 340 b is a capacitor on the common line 360 . In other words, the storage capacitor 346 b disposed in each of the pixel units 340 b is formed by the pixel electrode 344 and the common line 360 . That is, the storage capacitor 346 b is formed on the common line 360 , as shown in FIG. 2 . In addition, the storage capacitor 346 b can be arranged in the structure of metal layer/insulator layer/ITO layer (MII), or metal layer/insulator layer/metal layer (MIM). The driving method, structure and effect of the LCD panel 100 b in the present embodiment are similar to those in the first embodiment and thus will no longer be repeated hereinafter.

FIG. 3A is a schematic cross-sectional view of an LCD panel according to the third embodiment of the present invention. FIG. 3B is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel in FIG. 3A . Referring to both FIG. 3A and FIG. 3B , an LCD panel 100 c includes an opposite substrate 200 , an active matrix substrate 300 ′ and a liquid crystal layer 400 . The opposite substrate 200 is disposed above the active matrix substrate 300 ′, and the liquid crystal layer 400 is disposed between the active matrix substrate 300 ′ and the opposite substrate 200 .

The active matrix substrate 300 ′ includes a substrate 310 , a plurality of scan lines 320 a and 320 b (only two scan lines shown in FIG. 3B ), a plurality of data lines 330 a and 330 b (only two data lines shown in FIG. 3B ), a plurality of pixel units 340 c and a plurality of common lines 360 . The scan lines (including 320 a and 320 b ), the data lines (including 330 a and 330 b ), the pixel units 340 c and the common lines 360 are all disposed on the substrate 310 . The plurality of the pixel units 340 c are electrically connected with the corresponding scan lines (e.g. scan lines 320 a or 320 b ) and the data lines (e.g. data lines 330 a or 330 b ) respectively. The common lines 360 are disposed between two adjacent scan lines (e.g. between the scan lines 320 a and 320 b ).

Each of the pixel units 340 c includes an active device 342 , a pixel electrode 344 and a pre-charge component 348 . In each of the pixel units 340 c , the active device 342 is electrically connected with the corresponding scan line 320 b (or 320 a ), the data line 330 a (or 330 b ) and the pixel electrode 344 (as shown in FIG. 3B ). The active device 342 is a TFT, for example. Each of the pre-charge components 348 is electrically connected with the preceding scan line 320 a of the pixel unit 340 c , the pixel electrode 344 and the common line 360 . The pre-charge component 348 can be a TFT having a gate 348 a , a drain 348 b and a source 348 c . The gate 348 a is electrically connected with the preceding scan line 320 a , and the drain 348 b and the source 348 c are electrically connected with the common line 360 and the corresponding pixel electrode 344 respectively.

In the present embodiment, each of the pixel units 340 c can further include a storage capacitor 346 c electrically connected with the active device 342 via the pixel electrode 344 . The storage capacitor 346 c can be formed on the common line 360 . In addition, the storage capacitor 346 c can be arranged in the structure of metal layer/insulator layer/ITO layer (MII), or metal layer/insulator layer/metal layer (MIM).

The driving method of the LCD panel in the present embodiment is similar to the first embodiment, and the present embodiment will no longer be repeated hereinafter. The two embodiments merely differ in the method for the pre-charge component 348 to pre-charge the pixel unit 340 c.

For example, in each of the pixel units 340 c , when the pre-charge component 348 is turned on via the scan line 320 a electrically connected therewith, the pixel electrode 344 can have the same voltage level as the common line 360 , that is, the voltage level of the pixel electrode 344 can be equal to common voltage level of the common line 360 . Thus, with the pre-charge component 348 , the pixel unit 340 c is pre-charged so as to mitigate the problem of insufficient charging.

FIG. 4 is a schematic circuit diagram illustrating two adjacent pixel units on the same row of the LCD panel according to the forth embodiment of the present invention. Referring to FIG. 4 , the present embodiment is similar to the third embodiment. The difference between the present embodiment and the third embodiment is that there are a plurality of pixel units 340 d in a LCD panel 100 d of the forth embodiment.

Specifically, the storage capacitor 346 d in each of the pixel units 340 d is basically formed by the pixel electrode 344 and the scan line 320 a . That is, the storage capacitor 346 d is formed on the scan line 320 a . Although only the storage capacitor 346 d formed on the scan line 320 a is shown in FIG. 4 , the storage capacitor 346 d shown in FIG. 4 is merely illustrated as an example and not intended to limit the present invention. In addition, the storage capacitor 346 d can be arranged in the structure of metal layer/insulator layer/ITO layer (MII) or metal layer/insulator layer/metal layer (MIM). The driving method, structure and effect of the LCD panel 100 d in the present embodiment are similar to the third embodiment, which thus will no longer be repeated hereinafter.

In view of the foregoing, with a plurality of pre-charge components, the pixel units in the LCD panel are able to be pre-charged before being charged, and therefore, the display quality of the LCD panel can be enhanced. In addition, since the present invention can achieve the effect of pre-charging without adopting complicated circuits, the present invention is more simple and useful than the conventional technique.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.