Array substrate and display apparatus having the same

This application claims priority from and the benefit of Korean Patent Application No. 10-2006-0090247, filed on Sep. 18, 2006, which is hereby incorporated by reference for all purposes as if fully set forth herein.

1. Field of the Invention

The present invention relates to an array substrate and a display apparatus including the array substrate. More particularly, the present invention relates to an array substrate that may improve response speed and a display apparatus including the array substrate.

2. Discussion of the Background

In general, a liquid crystal display includes a liquid crystal display panel including a lower substrate, an upper substrate facing the lower substrate, and a liquid crystal layer interposed between the lower substrate and the upper substrate to display an image.

The liquid crystal display panel may include a plurality of gate lines, a plurality of data lines, and a plurality of pixels connected to the gate lines and the data lines, all of which are formed on the liquid crystal display panel. The liquid crystal display panel includes a gate driving circuit directly formed thereon through a thin film process. The gate driving circuit sequentially outputs a gate signal to the gate lines.

Generally, a gate driving circuit includes a shift register in which plural stages are connected to each other one after another. That is, each stage applies a gate signal to a corresponding gate line and controls the drive of a next stage.

However, the number of the gate lines increases as the liquid crystal display panel becomes larger in size and higher in resolution. When the number of gate lines increases, an active period (one horizontal scanning period, 1H period) during which pixels connected to one row are operated is shortened. As a result, the charge rate of the liquid crystal may decrease, thereby decreasing the response speed of a display apparatus.

The present invention provides an array substrate that may improve response speed and display quality.

The present invention also provides a display apparatus including the above array substrate.

Additional features of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

The present invention discloses an array substrate including a base substrate and a plurality of pixels arranged on the base substrate. Each pixel includes a gate line, a data line, a thin film transistor, a pixel electrode, and a pre-charging part. The gate line receives a gate pulse during a present 1H period (one horizontal scanning period), and the data line receives a pixel voltage having a polarity inverted at every frame. The data line is insulated from the gate line and crosses the gate line. The thin film transistor is connected to the gate line and the data line to output the pixel voltage in response to the gate pulse during the present 1H period. The pixel electrode is connected to the thin film transistor to receive the pixel voltage during the present 1H period. The pre-charging part pre-charges the pixel electrode to a common voltage that is a reference voltage of the pixel voltage in response to a previous gate pulse during a previous 1H period.

The present invention also discloses a display apparatus including an array substrate, an opposite substrate, a gate driving circuit, and a data driving circuit. The array substrate includes a base substrate and a plurality of pixels arranged on the base substrate, and an opposite substrate coupled to the array substrate and facing the array substrate. The gate driving circuit applies a gate pulse to the pixels and the data driving circuit applies a pixel voltage having a polarity inverted at every frame to the pixels. Each pixel arranged on the array substrate includes a gate line, a data line, a thin film transistor, a pixel electrode, and a pre-charging part. The gate line receives the gate pulse during a present 1H period (one horizontal scanning period), and the data line receives the pixel voltage. The data line is insulated from the gate line and crosses the gate line. The thin film transistor is connected to the gate line and the data line to output the pixel voltage in response to the gate pulse during the present 1H period. The pixel electrode is connected to the thin film transistor to receive the pixel voltage during the present 1H period. The pre-charging part pre-charges the pixel electrode to a common voltage that is a reference voltage of the pixel voltage in response to a previous gate pulse during a previous 1H period.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

FIG. 1 is a plan view showing a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a circuit diagram showing one pixel having a horizontal pixel structure shown in FIG. 1 .

FIG. 3 is a waveform diagram showing a variation of a pixel voltage according to a gate pulse in one pixel of FIG. 2 .

FIG. 4 is a layout showing a pixel on an array substrate shown in FIG. 1 .

FIG. 5 is a sectional view taken along lines I-I′ and II-II′ shown in FIG. 4 .

FIG. 6 is a plan view showing a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 7 is a circuit diagram showing one pixel having a vertical pixel structure shown in FIG. 6 .

FIG. 8 is a layout showing a pixel on an array substrate shown in FIG. 6 .

FIG. 9 is a sectional view taken along lines III-III′ and IV-IV′ shown in FIG. 8 .

FIG. 10 is a plan view showing a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 11 is a circuit diagram showing one pixel having a vertical pixel structure shown in FIG. 10 .

FIG. 12 is a waveform diagram showing a variation of a pixel voltage according to a gate pulse in one pixel of FIG. 11 .

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals in the drawings denote like elements.

It will be understood that when an element or layer is referred to as being “on” or “connected to” another element or layer, it can be directly on or directly connected to the other element or layer, or intervening element or layers may be present. In contrast, when an element is referred to as being “directly on” or “directly connected to” another element or layer, there are no intervening elements or layers present.

FIG. 1 is a plan view showing a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1 , a liquid crystal display 500 includes a liquid crystal display panel 100 to display an image, a printed circuit board 400 arranged adjacent to the liquid crystal display panel 100 , and a tape carrier package (TCP) 300 connecting the liquid crystal display panel 100 and the printed circuit board 400 .

The liquid crystal display panel 100 includes an array substrate 110 , a color filter substrate 120 facing the array substrate 110 , and a liquid crystal layer (not shown) interposed between the array substrate 110 and the color filter substrate 120 . The array substrate 110 is divided into a display area DA on which the image is displayed, a first peripheral area PA 1 , a second peripheral area PA 2 , and a third peripheral area PA 3 . The peripheral areas PA 1 , PA 2 , and PA 3 are adjacent to the display area DA.

In the display area DA of the array substrate 110 , a plurality of pixel areas is defined in a matrix configuration. Particularly, in the display area DA, the pixel areas are defined by a plurality of gate lines GL 1 ˜GLn (n is an even-number larger than 2) extending in a first direction D 1 and a plurality of data lines DL 1 ˜DLm extending in a second direction D 2 substantially perpendicular to the first direction D 1 . The color filter substrate 120 includes a plurality of color pixels (e.g. red, green, and blue pixels) corresponding to the pixel areas arranged thereon.

The first peripheral area PA 1 is adjacent to the first ends of the gate lines GL 1 ˜GLn, and a first gate driving circuit 210 is arranged in the first peripheral area PA 1 to sequentially apply a gate pulse to the gate lines GL 1 ˜GLn. The first gate driving circuit 210 includes a shift register in which plural stages are connected to each other one after another. Each stage includes an output terminal connected to a corresponding first end of a gate line GL 1 ˜GLn. Thus, each stage is sequentially turned on to sequentially apply the gate pulse to a corresponding gate line GL 1 ˜GLn.

The second peripheral area PA 2 is adjacent to the second end of the gate lines GL 1 ˜GLn, and a second gate driving circuit 220 is arranged in the second peripheral area PA 2 to sequentially apply the gate pulse to the gate lines GL 1 ˜GLn. The second gate driving circuit 220 includes a shift register having a plurality of stages connected to each other one after another. Each stage includes an output terminal connected to a corresponding second end of a gate line GL 1 ˜GLn. Thus, each stage is sequentially turned on to sequentially apply the gate pulse to a corresponding gate line GL 1 ˜GLn.

Since the first and second ends of each gate line are connected to the first gate driving circuit 210 and the second driving circuit 220 , respectively, the gate pulse is input through both ends of the gate lines, which may prevent delay of the gate pulse.

In the present exemplary embodiment, the first driving circuit 210 and the second driving circuit 220 are substantially simultaneously formed on the array substrate 110 through a thin film process. The thin film process may be the same as that applied to form the pixels. Accordingly, the first gate driving circuit 210 and the second driving circuit 220 are integrated on the array substrate 110 , so that the driving chips on which the first gate driving circuit 210 and the second gate driving circuit 220 are mounted may be removed from the liquid crystal display 500 . As a result, the productivity of the liquid crystal display 500 may be improved and the size of the liquid crystal display 500 may be decreased.

The third peripheral area PA 3 is adjacent to one end of the data lines DL 1 ˜DLm, and a first end of the TCP 300 is attached to the third peripheral area PA 3 . A second end of the TCP 300 is attached to the printed circuit board 400 . A data driving chip 310 that provides a pixel voltage to the data lines DL 1 ˜DLm is mounted on the TCP 300 . Thus, the data driving chip 310 may provide the pixel voltage to the data lines DL 1 ˜DLm in response to various control signals from the printed circuit board 400 .

First and second gate control signals output from the printed circuit board 400 are provided to the first gate driving circuit 210 and the second gate driving circuit 220 through the TCP 300 , respectively. Thus, the first gate driving circuit 210 and the second gate driving circuit 220 provide the gate pulse to the gate lines GL 1 ˜GLn in response to the first gate control signal and the second gate control signal, respectively.

As shown in FIG. 1 , the pixels arranged on the array substrate 110 have a horizontal pixel structure in which the length in the first direction D 1 is longer than a length in the second direction D 2 . In the horizontal pixel structure, three consecutive pixels arranged along the second direction D 2 corresponding to red R, green G, and blue B pixels are defined as one pixel in which one color is displayed. When compared to a vertical pixel structure, the number of data lines is decreased and the number of gate lines is increased in the horizontal pixel structure.

In a liquid crystal display 500 that employs the horizontal pixel structure, the number of data driving chips 310 outputting a data signal decreases due to the decreased number of data lines, which may improve the productivity of the liquid crystal display 500 . On the other hand, although the number of gate lines increases, since the first gate driving circuit 210 and the second gate driving circuit 220 are integrated onto the array substrate 110 through a thin film process, the number of chips in the liquid crystal display 500 may not increase.

Hereinafter, the horizontal pixel structure will be described in detail with reference to FIG. 2 , FIG. 3 , FIG. 4 , and FIG. 5 .

FIG. 2 is a circuit diagram showing one pixel having the horizontal pixel structure shown in FIG. 1 , and FIG. 3 is a waveform diagram showing a variation of the pixel voltage according to the gate pulse.

Referring to FIG. 2 , one pixel includes a first pixel Pixj corresponding to a red pixel R, a second pixel P(i+1)xj corresponding to a green pixel G, and a third pixel P(i+2)xj corresponding to a blue pixel B. Each of the first, second, and third pixels Pixj, P(i+1)xj, and P(i+2)xj has a horizontal pixel structure.

The first pixel Pixj includes an i th gate line GLi, a j th data line DLj, a storage line SL, an i th thin film transistor T 1 i , an i th pre-charging transistor T 21 , and an i th pixel electrode PEi.

The i th thin film transistor T 1 i is connected to the i th gate line GLi and the j th data line DLj. Particularly, the i th thin film transistor T 1 i includes a gate electrode connected to the i th gate line GLi, a source electrode connected to the j th data line DLj, and a drain electrode connected to the i th pixel electrode PEi.

The i th pre-charging transistor T 21 is connected between an (i−1) th gate line GLi−1 and the storage line SL. Particularly, the i th pre-charging transistor T 21 includes a gate electrode connected to the (i−1) th gate line GLi−1, a source electrode connected to the storage line SL, and a drain electrode connected to the i-th pixel electrode PEi.

The second pixel P(i+1)xj includes an (i+1) th gate line GLi+1, the j th data line DLj, the storage line SL, an (i+1) th thin film transistor T 1 ( i+ 1), an (i+1) th pre-charging transistor T 2 ( i+ 1), and an (i+1) th pixel electrode PEi+1.

The (i+1) th thin film transistor T 1 ( i+ 1) is connected to the (i+1) th gate line GLi+1, the j th data line DLj and the (i+1) th pixel electrode PEi+1. The (i+1) th pre-charging transistor T 2 ( i+ 1) is connected to the i th gate line GLi, the storage line SL, and the (i+1) th pixel electrode PEi+1.

The third pixel P(i+2)xj includes an (i+2) th gate line GLi+2, the j th data line DLj, the storage line SL, an (i+2) th thin film transistor T 1 ( i+ 2), an (i+2) th pre-charging transistor T 2 ( i+ 2), and an (i+2) th pixel electrode PEi+2.

The (i+2) th thin film transistor T 1 ( i+ 2) is connected to the (i+2) th gate line GLi+2, the j th data line DLj, and the (i+2) th pixel electrode PEi+2. The (i+2) th pre-charging transistor T 2 ( i+ 2) is connected to the (i+1) th gate line GLi+1, the storage line SL, and the (i+2) th pixel electrode PEi+2.

As shown in FIG. 2 and FIG. 3 , the first pixel Pixj pre-charges the i th pixel electrode PEi to a common voltage Vcom in response to an (i−1) th gate pulse Gi−1 applied to the (i−1) th gate line GLi−1. Particularly, when the i th pre-charging transistor T 2 i is turned on in response to the (i−1) th gate pulse Gi−1, the common voltage Vcom applied to the storage line SL is applied to the i th pixel electrode PEi through the i th precharging transistor T 2 i . Thus, the i th pixel electrode PEi is pre-charged to the common voltage Vcom during a 1H period (an (i−1) th active period Ai−1) when the (i−1) th gate pulse Gi−1 is generated.

Then, the i th thin film transistor T 1 i is turned on in response to the i th gate pulse Gi, so that an i th pixel voltage Vpi applied to the j th data line DLj is applied to the i th pixel electrode PEi during an i th active period Ai.

When a polarity of the i th pixel voltage Vpi applied to the i th pixel electrode PEi is inverted at every frame, the common voltage Vcom is applied to the i th pixel electrode PEi as a reference voltage during the (i−1) th active period Ai−1. Thus, a time when the i th pixel voltage Vpi reaches to a target voltage may be shortened during the i th active period Ai, so that a response speed of liquid crystal may be improved.

The (i+1) th pixel electrode PEi+1 of the second pixel P(i+1)xj is precharged to the common voltage Vcom in response to the i th gate pulse Gi during the i th active period Ai, and then receives an (i+1) th pixel voltage Vpi+1 in response to the (i+1) th gate pulse Gi+1 during an (i+1) th active period Ai+1.

The (i+2) th pixel electrode PEi+2 of the third pixel P(i+2)xj is pre-charged to the common voltage Vcom in response to the (i+1) th gate pulse Gi+1 during the (i+1) th active period Ai+1, and then receives an (i+2) th pixel voltage Vpi+2 in response to an (i+2) th gate pulse Gi+2 during an (i+2) th active period Ai+2.

As described above, when the polarity of the pixel voltage applied to each pixel is inverted at every frame, present pixels are pre-charged to the common voltage that is a reference voltage of a polarity in response to a previous gate pulse, and then receive a target pixel voltage. Thus, the time required for the pixel voltage of each pixel to reach the target voltage may be shortened during the active period, so that the response speed of the liquid crystal may be improved.

FIG. 4 is a layout showing a pixel on the array substrate shown in FIG. 1 , and

FIG. 5 is a sectional view taken along lines I-I′ and II-II′ shown in FIG. 4 .

The array substrate 110 includes a base substrate 111 and the pixels arranged on the base substrate 111 . Since the pixels have a same configuration, only one pixel will be described in detail with reference to FIG. 4 and FIG. 5 .

Referring to FIG. 4 and FIG. 5 , the (i−1) th gate line GLi−1 and the i th gate line GLi are arranged on the base substrate 111 extending in the first direction D 1 . In the present embodiment, the i th gate line GLi is defined as a present gate line and the (i−1) th gate line GLi−1 is defined as a previous gate line with reference to the (ixj) th pixel.

The gate electrode GE 1 of the i th thin film transistor T 1 i and the gate electrode GE 2 of the i th pre-charging transistor T 2 i are formed on the base substrate 111 . Particularly, the gate electrode GE 1 of the i th thin film transistor T 1 i is branched from the i th gate line GLi, and the gate electrode GE 2 of the i th pre-charging transistor T 2 i is branched from the (−1) th gate line GLi−1.

The (i−1) th gate line GLi−1, the i th gate line GLi, the gate electrode GE 1 of the i th thin film transistor T 1 i , and the gate electrode GE 2 of the i th pre-charging transistor T 2 i , which are arranged on the base substrate 111 , are covered by a gate insulating layer 112 .

The j th data line DLj extending in the second direction D 2 , a first storage line SL 1 , a second storage line SL 2 , and a third storage line SL 3 are arranged on the gate insulating layer 112 . The first storage line SL 1 and the second storage line SL 2 extend in the first direction D 1 . Particularly, the first storage line SL 1 is arranged adjacent to the (i−1) th gate line GLi−1 and the second storage line SL 2 is arranged adjacent to the i th gate line GLi. The third storage line SL 3 extends in the second direction D 2 and connects the first storage line SL 1 and the second storage line SL 2 .

The source electrode SE 1 and the drain electrode DE 1 of the i th thin film transistor T 1 i and the source electrode SE 2 and the drain electrode DE 2 of the i th pre-charging transistor T 21 are formed on the gate insulating layer 112 . The source electrode SE 1 of the i th thin film transistor T 1 i is branched from the j th data line DLj, and the drain electrode DEL of the i th thin film transistor T 1 i is spaced apart from the source electrode SE 1 by a predetermined distance at an upper portion of the gate electrode GE 1 . The source electrode SE 2 of the i th pre-charging transistor T 21 is branched from the first storage line SL 1 , and the drain electrode DE 2 of the i th pre-charging transistor T 2 i is spaced apart from the source electrode SE 2 by a predetermined distance at an upper portion of the gate electrode GE 2 . Thus, the i th thin film transistor T 1 i and the i th pre-charging transistor T 21 are completed on the base substrate 111 .

The j th data line DLj, the first, second, and third storage lines SL 1 , SL 2 , and SL 3 , the i th thin film transistor T 1 i , and the i th pre-charging transistor T 21 , which are arranged on the gate insulating layer 112 , are covered by a protective layer 113 . The protective layer 113 is provided with a first contact hole C 1 and a second contact hole C 2 formed therethrough to expose the drain electrode DE 1 of the i th thin film transistor T 1 i and the drain electrode DE 2 of the i th pre-charging transistor T 21 , respectively.

The i th pixel electrode PEi is formed on the protective layer 113 . The i th pixel electrode PEi includes a transparent conductive material. Also, the i th pixel electrode PEi is connected to the drain electrode DE 1 of the i th thin film transistor T 1 i through the first contact hole C 1 and is connected to the drain electrode DE 2 of the i th pre-charging transistor T 21 through the second contact hole C 2 .

According to the above, the i th pre-charging transistor T 21 is connected between the previous gate line GLi−1 and the first storage line SL 1 to pre-charge the i th pixel electrode PEi to the common voltage Vcom in response to the previous gate pulse.

As an example of the present exemplary embodiment, in the pixel having the horizontal pixel structure, the first, second, and third storage lines SL 1 , SL 2 , and SL 3 are formed from the same layer with the j th data line DLj. Thus, the source electrode SE 2 of the i th pre-charging transistor T 21 may be branched from one of the first, second, and third storage lines SL 1 , SL 2 , and SL 3 . Therefore, the process to form the i th pre-charging transistor T 21 on the array substrate 110 may be simplified.

FIG. 6 is a plan view showing a liquid crystal display according to another exemplary embodiment of the present invention, and FIG. 7 is a circuit diagram showing one pixel having a vertical pixel structure shown in FIG. 6 . In FIG. 6 , the same reference numerals denote the same elements in FIG. 1 , and thus, detailed descriptions of the same elements will be omitted.

Referring to FIG. 6 , a liquid crystal display 503 includes a liquid crystal display panel 103 to display an image, a printed circuit board 400 arranged adjacent to the liquid crystal display panel 103 , and a tape carrier package (TCP) 300 connecting the liquid crystal display panel 103 and the printed circuit board 400 .

The liquid crystal display panel 103 includes an array substrate 110 , a color filter substrate 120 facing the array substrate 110 , and a liquid crystal layer (not shown) interposed between the array substrate 110 and the color filter substrate 120 . The array substrate 110 is divided into a display area DA on which the image is displayed and a first peripheral area PA 1 and a third peripheral area PA 3 that are adjacent to the display area DA.

In the display area DA of the array substrate 110 , a plurality of pixel areas is defined in a matrix configuration. The first peripheral area PA 1 is adjacent to the first end of the gate lines GL 1 ˜GLn, and a gate driving circuit 210 is arranged in the first peripheral area PA 1 to sequentially apply a gate pulse to the gate lines GL 1 ˜GLn. The gate driving circuit 210 includes a shift register having a plurality of stages connected to each other one after another. Each stage includes an output terminal connected to a corresponding first end of a gate line GL 1 ˜GLn. Thus, each stage is sequentially turned on to sequentially apply the gate pulse to the corresponding gate line of the gate lines GL 1 ˜GLn.

The third peripheral area PA 3 is adjacent to one end of the data lines DL 1 ˜DLm, and a first end of the TCP 300 is attached to the third peripheral area PA 3 . A second end opposite to the first end of the TCP 300 is attached to the printed circuit board 400 . A data driving chip 310 that provides a pixel voltage to the data lines DL 1 ˜DLm is mounted on the TCP 300 .

As shown in FIG. 6 , each pixel arranged on the array substrate 110 has a vertical pixel structure in which the length in the second direction D 2 is longer than a length in the first direction D 1 . In the vertical pixel structure, three consecutive pixels arranged along the first direction D 1 corresponding to red R, green G, and blue B pixels are defined as one pixel on which one color information is displayed.

Thus, in a liquid crystal display 503 employing the vertical pixel structure, the number of data lines is increased and the number of gate lines is decreased when compared to the horizontal pixel structure shown in FIG. 1 .

Referring to FIG. 7 , one pixel includes a first pixel Pixj corresponding to the red pixel R, a second pixel Pix(j+1) corresponding to the green pixel G, and a third pixel Pix(j+2) corresponding to the blue pixel B. Each of the first, second, and third pixels has the vertical pixel structure.

The first pixel Pixj includes an i th gate line GLi, a j th data line DLj, a storage line SL, a j th thin film transistor T 1 j , a j th precharging transistor T 2 j , and a j th pixel electrode PEj.

The j th thin film transistor T 1 j is connected to the i th gate line GLi and the j th data line DLj. Particularly, the j th thin film transistor T 1 j includes a gate electrode connected to the i th gate line GLi, a source electrode connected to the j th data line DLj, and a drain electrode connected to the j th pixel electrode PEj.

The j th pre-charging transistor T 2 j is connected to the (−1) th gate line GLi−1 and the storage line SL. Particularly, the j th pre-charging transistor T 2 j includes a gate electrode connected to the (−1) th gate line GLi−1, a source electrode connected to the storage line SL, and a drain electrode connected to the j th pixel electrode PEj.

The second pixel Pix(j+1) includes the i th gate line GLi, a (j+1) th data line DLj+1, the storage line SL, a (j+1) th thin film transistor T 1 ( j+ 1), a (j+1) th pre-charging transistor T 2 ( j+ 1), and a (j+1) th pixel electrode PEj+1.

The (j+1) th thin film transistor T 1 ( j+ 1) is connected to the i th gate line GLi, the (j+1) th data line DLj+1, and the (j+1) th pixel electrode PEj+1. The (j+1) th pre-charging transistor T 2 ( j+ 1) is connected to the (i−1) th gate line GLi−1, the storage line SL, and the (j+1) th pixel electrode PEj+1.

The third pixel Pix(j+2) includes the i th gate line GLi, a (j+2) th data line DLj+2, the storage line SL, a (j+ 2 ) th thin film transistor T 1 ( j+ 2), a (j+2) th pre-charging transistor T 2 ( j+ 2), and a (j+2) th pixel electrode PEj+2.

The (j+2) th thin film transistor T 1 ( j+ 2) is connected to the i th gate line GLi, the (j+2) th data line DLj+2, and the (j+2) th pixel electrode PEj+2. The (j+2) th pre-charging transistor T 2 ( j+ 2) is connected to the (i−1) th gate line GLi−1, the storage line SL, and the (j+2) th pixel electrode PEj+2.

The first, second, and third pixels Pixj, Pix(j+1), and Pix(j+2) pre-charge the j th , the (j+1) th , and the (j+2) th pixel electrodes PEj, PEj+1, and PEj+2 to a common voltage, respectively, in response to an (i−1) th gate pulse Gi−1 applied to the (i−1) th gate line GLi−1. Particularly, when the j th , the (j+1) th , and the (j+2) th precharging transistors T 2 j , T 2 ( j+ 1), and T 2 ( j+ 2) are turned on by the (i−1) th gate pulse Gi−1, the common voltage applied to the storage line SL is applied to the j th , the (j+1) th , and the (j+2) th pixel electrodes PEj, PEj+1, and PEj+2 through the j th , the (j+1) th , and the (j+2) th precharging transistors T 2 j , T 2 ( j+ 1), and T 2 ( j+ 2), respectively. Thus, the j th , the +1) th , and the (j+2) th pixel electrodes PEj, PEj+1, and PEj+2 are precharged to the common voltage during a 1H period (an (i−1) th active period) when the (i−1) th gate pulse Gi−1 is generated.

Then, the j th , the (j+1) th , and the (j+2) th thin film transistors T 1 j , T 1 ( j+ 1), and T 1 ( j+ 2) are turned on during an i th active period in response to the i th gate pulse Gi in order to apply the j th , the (j+1) th , and the (j+2) th pixel voltages applied through the j th , (j+1) th , and (j+2) th data lines DLj, DLj+1, and DLj+2 to the j th , the (j+1) th , and the (j+2) th pixel electrodes PEj, PEj+1, and PEj+2, respectively.

As described above, a present pixel electrode is pre-charged to the common voltage during a previous active period, so that the time required for a pixel voltage to reach a target voltage may be shortened during a present active period. Especially, when a polarity of the pixel voltage applied to each pixel is inverted at every frame, the present pixels are pre-charged to the common voltage that is a reference voltage of a polarity, and then receives a target pixel voltage in response to a present gate pulse. Thus, the time required for the pixel voltage to reach the target voltage may be shortened during the active period, so that the response speed of the liquid crystal may be improved.

FIG. 8 is a layout showing a pixel on the array substrate shown in FIG. 6 , and FIG. 9 is a sectional view taken along lines III-III′ and IV-IV′ shown in FIG. 8 .

The array substrate 110 includes a base substrate 111 and a plurality of pixels arranged on the base substrate 111 . Since each pixel has the same configuration, only one pixel (e.g. the (ixj) th pixel) will be described in detail with reference to FIG. 8 and FIG. 9 .

Referring to FIG. 8 and FIG. 9 , the (i−1) th gate line GLi−1, the i th gate line GLi, a first storage line SL 1 , a second storage line SL 2 , and a third storage line SL 3 are formed on the base substrate 111 . The i th gate line GLi is defined as a present gate line and the (i−1) th gate line is defined as a previous gate line with reference to the (ixj) th pixel. The (i−1) th gate line GLi−1 and the i th gate line GLi extend in the first direction D 1 . The first storage line SL 1 and the second storage line SL 2 extend in the second direction D 2 parallel to each other and are arranged between the (i−1) th gate line GLi−1 and the i th gate line GLi. The third storage line SL 3 extends in the first direction D 1 and connects the first storage line SL 1 and the second storage line SL 2 .

A gate electrode GE 1 of a j th thin film transistor T 1 j and a gate electrode GE 2 of a ji th pre-charging transistor T 2 j are formed on the base substrate 111 . Particularly, the gate electrode GE 1 of the j th thin film transistor T 1 j is branched from the i th gate line GLi and the gate electrode GE 2 of the j th pre-charging transistor T 2 j is branched from the (i−1) th gate line GLi−1.

The (i−1) th gate line GLi−1, the i th gate line GLi, the first, second, and third storage lines SL 1 , SL 2 , and SL 3 , the gate electrode GE 1 of the j th thin film transistor T 1 j , and the gate electrode GE 2 of the j th pre-charging transistor T 2 j , which are arranged on the base substrate 111 , are covered by a gate insulating layer 112 . The gate insulating layer 112 is provided with a third contact hole C 3 formed therethrough in order to expose one end of the first storage line SL 1 .

Then, the j th data line DLj extending in the second direction D 2 is arranged on the gate insulating layer 112 . Also, a source electrode SE 1 and a drain electrode DEL of the j th thin film transistor T 1 j and a source electrode SE 2 and a drain electrode DE 2 of the j th pre-charging transistor T 2 j are formed on the gate insulating layer 112 . The source electrode SE 1 of the j th thin film transistor T 1 j is branched from the j th data line DLj, and the drain electrode DEL of the j th thin film transistor T 1 j is spaced apart from the source electrode SE 1 by a predetermined distance at an upper portion of the gate electrode GE 1 .

The source electrode SE 2 of the j th pre-charging transistor T 2 j is connected to the first storage line SL 1 , and the drain electrode DE 2 of the j th pre-charging transistor T 2 j is spaced apart from the source electrode SE 2 by a predetermined distance at an upper portion of the gate electrode GE 2 . The source electrode SE 2 of the j th pre-charging transistor T 2 j is connected to the first storage line SL 1 through the third contact hole C 3 formed through the gate insulating layer 112 . Thus, the j th thin film transistor T 1 j and the j th pre-charging transistor T 2 j are completed on the base substrate 111 .

The j th data line DLj, the j th thin film transistor T 1 j , and the j th pre-charging transistor T 2 j arranged on the gate insulating layer 112 are covered by a protective layer 113 . The protective layer 113 is provided with a first contact hole C 1 and a second contact hole C 2 through which the drain electrode DE 1 of the j th thin film transistor T 1 j and the drain electrode DE 2 of the j th pre-charging transistor T 2 j are exposed, respectively.

The j th pixel electrode PEj is formed on the protective layer 113 , and the j th pixel electrode PEj is connected to the drain electrode DE 1 of the j th thin film transistor T 1 j through the first contact hole C 1 and the drain electrode DE 2 of the j th pre-charging transistor T 2 j through the second contact hole C 2 .

As described above, the j th pre-charging transistor T 2 j is connected between the previous gate line GLi−1 and the first storage line SL 1 to pre-charge the j th pixel electrode PEj to the common voltage in response to the previous gate pulse.

In FIG. 8 and FIG. 9 , a structure in which the first, second, and third storage lines SL 1 , SL 2 , and SL 3 are formed from the same layer as the i th gate line GLi in a pixel having the vertical pixel structure has been described. However, in the pixel having the vertical pixel structure, the first, second, and third storage lines SL 1 , SL 2 , and SL 3 may be formed from the same layer with the j th data line DLj.

FIG. 10 is a plan view showing a liquid crystal display according to another exemplary embodiment of the present invention. In FIG. 10 , the same reference numerals denote the same elements in FIG. 6 , and thus, detailed descriptions of the same elements will be omitted.

Referring to FIG. 10 , a liquid crystal display 505 includes an array substrate 110 that is divided into a display area DA on which the image is displayed, a first peripheral area PA 1 , a second peripheral area PA 2 , and a third peripheral area PA 3 . The peripheral areas PA 1 , PA 2 , and PA 3 are adjacent to the display area DA.

In the display area DA of the array substrate 110 , a plurality of pixel areas is defined in a matrix configuration. The first peripheral area PA 1 is adjacent to the first end of the gate lines GL 1 ˜GLn, and a first gate driving circuit 210 is arranged in the first peripheral area PA 1 to sequentially apply a gate pulse to the gate lines GL 1 ˜GLn. The second peripheral area PA 2 is adjacent to the second end of the gate lines GL 1 ˜GLn, and a second gate driving circuit 220 is arranged in the second peripheral area PA 2 to sequentially apply the gate pulse to the gate lines GL 1 ˜GLn.

The third peripheral area PA 3 is adjacent to one end of the data lines DL 1 ˜DLm, and a TCP 300 is attached to the third peripheral area PA 3 . A data driving chip 310 that provides a pixel voltage to the data lines DL 1 ˜DLm is mounted on the TCP 300 .

As shown in FIG. 10 , each pixel arranged on the array substrate 110 has a vertical pixel structure of which a length in the second direction D 2 is longer than a length in the first direction D 1 . In the vertical pixel structure, three consecutive pixels arranged along the first direction D 1 corresponding to red R, green G, and blue B pixels are defined as one pixel in which one color is displayed.

In FIG. 10 , one data line is connected to two pixels that are arranged on the left and right sides thereof. Thus, in the liquid crystal display 505 shown in FIG. 10 , the number of data lines is decreased by half and the number of gate lines is increased by two times when compared to the liquid crystal display 503 shown in FIG. 6 .

FIG. 11 is a circuit diagram showing one pixel having the vertical pixel structure shown in FIG. 10 , and FIG. 12 is a waveform diagram showing a variation of a pixel voltage according to a gate pulse in one pixel shown in FIG. 11 .

Referring to FIG. 11 , one pixel includes a first pixel P L ixj corresponding to a red pixel R, a second pixel P R ixj corresponding to a green pixel G, and a third pixel P L ix(j+1) corresponding to a blue pixel B. Each of the first, second, and third pixels P L ixj, P R ixj, and P L ix(j+1) has a vertical pixel structure.

The first pixel P L ixj includes an i th gate line GLi, a j th data line DLj, a storage line SL, a j th left thin film transistor T 1 j , a j th left pre-charging transistor T 2 j , and a j th left pixel electrode PEj(L).

The j th left thin film transistor T 1 j is connected to the i th gate line GLi and the j th data line DLj. Particularly, the j th left thin film transistor T 1 j includes a gate electrode connected to the i th gate line GLi, a source electrode connected to the j th data line DLj and a drain electrode connected to the j th left pixel electrode PEj(L).

The j th left pre-charging transistor T 2 j is connected to the (i−1) th gate line GLi−1 and the storage line SL. Particularly, the j th left pre-charging transistor T 2 j includes a gate electrode connected to the (−1) th gate line GLi−1, a source electrode connected to the storage line SL, and a drain electrode connected to the j th left pixel electrode PEj(L).

The second pixel P R ixj includes an (i+1) th gate line GLi+1, the j th data line DLj, the storage line SL, a j th right thin film transistor T 3 j , a j th right pre-charging transistor T 4 j , and a j th right pixel electrode PEj(R).

The j th right thin film transistor T 3 j is connected to the (i+1) th gate line GLi+1, the j th data line DLj, and the j th right pixel electrode PEj(R). The j th right pre-charging transistor T 4 j is connected to the i th gate line GLi, the storage line SL, and the j j th right pixel electrode PEj(R).

The third pixel includes the i th gate line GLi, an (j+1) th data line DLj+1, the storage line SL, a (j+1) th left thin film transistor T 1 ( j+ 1), a (j+1) th left pre-charging transistor T 2 ( j+ 1), and a (j+1) th left pixel electrode PEj+1(L).

The (j+1) th left thin film transistor T 1 ( j+ 1) is connected to the i th gate line GLi, the (j+1) th data line DLj+1, and the (j+1) th left pixel electrode PEj+1(L). The (j+1) th left pre-charging transistor T 2 ( j+ 1) is connected to the (i−1) th gate line GLi−1, the storage line SL, and the (j+1) th left pixel electrode PEj+1(L).

As shown in FIG. 11 and FIG. 12 , the first and third pixels P L ixj and P L ix(j+1) pre-charge the j th left pixel electrode PEj(L) and the (j+1) th left pixel electrode PEj+1(L) to the common voltage Vcom in response to an (−1) th gate pulse Gi−1 applied to the (−1) th gate line GLi−1. Particularly, when the j th left pre-charging transistor T 2 j and the (j+1) th left pre-charging transistor T 2 ( j+ 1) are turned on in response to the (i−1) th gate pulse Gi−1, the common voltage Vcom applied to the storage line SL is applied to the j th left pixel electrode PEj(L) and the (j+1) th left pixel electrode PEj+1(L) through the j th left pre-charging transistor T 2 j and the (j+1) th left pre-charging transistor T 2 ( j+ 1), respectively. Thus, the j th left pixel electrode PEj(L) and the (j+1) th left pixel electrode PEj+1(L) are pre-charged to the common voltage Vcom during the 1H period (an (i−1) th active period Ai−1) when the (−1) th gate pulse Gi−1 is generated.

Then, the j th left thin film transistor T 1 j and the (j+1) th left thin film transistor T 1 ( j+ 1) are turned on in response to an i th gate pulse Gi during an i th active period Ai to apply a j th left pixel voltage Vpj(L) and a (j+1) th left pixel voltage Vpj+1(L), which are applied through the j th data line DLj and the (j+1) th data line DLj+1, to the j th left pixel electrode PEj(L) and the (j+1) th left pixel electrode PEj+1(L), respectively.

Also, the j th right pre-charging transistor T 4 j is turned on in response to the i th gate pulse Gi during the i th active period Ai, so that the common voltage Vcom is pre-charged in the j th right pixel electrode PEj(R). Then, when the j th right thin film transistor T 3 j is turned on in response to the (i+1) th gate pulse Gi+1, a j th right pixel voltage Vpj(R) is applied through the j th data line DLj to the j th right pixel electrode PEj(R) during an (i+1) th active period Ai+1.

As a result, when a time during which pixels connected to one row are turned on is defined as a 1H period, even-numbered pixels among the pixels connected to one row are turned on in response to the i th gate pulse Gi generated during an earlier H/2 period, and odd-numbered pixels are turned on in response to the (i−1) th gate pulse Gi−1 during a later H/2 period. Also, the even-numbered pixels are pre-charged to the common voltage Vcom in response to the (i−1) th gate pulse Gi−1, and the odd-numbered pixels are pre-charged to the common voltage Vcom in response to the i th gate pulse Gi.

As described above, the time required for the pixel voltage to reach the target voltage may be shortened during the present active period since the present pixel electrode is pre-charged to the common voltage during the previous active period. Particularly, when the polarity of the pixel voltage applied to each pixel is inverted at every frame, present pixels are pre-charged to the common voltage, which is a reference voltage of polarity, and then receive the target pixel voltage. Thus, the time required for the pixel voltage to reach the target voltage may be shortened during the active period, thereby improving the response speed of the liquid crystal.

In FIG. 1 , FIG. 2 , FIG. 3 , FIG. 4 , FIG. 5 , FIG. 6 , FIG. 7 , FIG. 8 , FIG. 9 , FIG. 10 , FIG. 11 , and FIG. 12 , only structures in which the gate driving circuit is directly formed on an array substrate 110 have been described. However, the gate driving circuit may be prepared in the form of a chip to be mounted on the array substrate 110 in a chip-on-glass method or on the TCP.

Although not shown in figures, the method of the present invention in which the pixel electrode is pre-charged to the common voltage may be employed in liquid crystal displays with a wide viewing angle characteristics, for example, Patterned Vertical Alignment mode liquid crystal displays, Multi-domain Vertical Alignment mode liquid crystal displays, Super-Patterned Vertical Alignment (S-PVA) mode liquid crystal displays, etc.

Particularly, the S-PVA mode liquid crystal display includes a pixel having main and sub pixels to which different sub voltages are applied in order to form a domain having different gray-scales in the pixel. Since human eyes looking at the liquid crystal display only recognize an intermediate value between the two sub voltages, a deterioration of a lateral viewing angle due to a distorted gamma curve below an intermediate gray-scale may be prevented, thereby improving the lateral visibility of the liquid crystal display.

The above S-PVA mode liquid crystal display is classified into a coupling capacitor (CC) type and a two transistor (TT) type according to a driving method thereof. In the CC-type S-PVA mode liquid crystal display, a coupling capacitor is added between a main pixel electrode and a sub pixel electrode to drop a data voltage applied to the sub pixel electrode, so that a pixel voltage that is lower than the main pixel voltage is applied as a sub pixel voltage. Meanwhile, in the TT-type S-PVA mode liquid crystal display, a main pixel voltage and a sub pixel voltage having different voltage levels are applied to a main pixel electrode and a sub pixel electrode, respectively, using two transistors that are turned on for a predetermined time interval. Thus, in case of the TT-type driving method, the time needed to charge the main and sub pixel voltages may be decreased by the H/2 period in comparison with the CC-type driving method.

Accordingly, in the S-PVA mode liquid crystal display employing the TT-type driving method, a charge rate of the liquid crystal in main and sub pixel areas may be improved since the main and sub pixel electrodes are pre-charged to the common voltage, thereby improving the response speed of the S-PVA liquid crystal display.

According to the above, the present pixel electrode is pre-charged to the common voltage that is the reference pixel voltage in response to the previous gate pulse during the previous 1H period, and the pixel voltage is applied to the present pixel in response to the present gate pulse during the present 1H period.

Thus, the time required for the pixel voltage of each pixel to reach the target voltage during the active period, in which present pixels connected to one row are operated, may be shortened, thereby improving the response speed of the liquid crystal.

Also, in conventional methods in which the present pixel is pre-charged to the previous pixel voltage, a ghost phenomenon where an image having a higher gray-scale than a desired gray-scale is displayed due to an overcharged present pixel may occur. However, according to exemplary embodiments of the present invention, the present pixel is pre-charged to the common voltage, which is used as the reference voltage of the pixel voltage. Thus, the ghost phenomenon may be prevented, thereby improving the display quality of the display apparatus.

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. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.