KR20040038250A - In-Plane Switching mode Liquid Crystal Display Device - Google Patents

Abstract

PURPOSE: An in-plane switching LCD device is provided to use a gate driver that applies different common voltages to adjacent storage lines with a source driver having the same data output signal polarity as a dot inversion system, thereby applying a higher pixel voltage to a liquid crystal. CONSTITUTION: A shift register(310) inputs a gate start pulse signal(GSP) and a left/right selection signal(L/R) from a microcomputer, is synchronized with a gate shift clock signal(GSC), and sequentially stores scanning signals(Gout1,Gout2,...,Goutn) to be applied to each gate line. A level shifter(320) shifts the scanning signals(Gout1,Gout2,...,Goutn) in response to a gate output enable signal(GOE) of the microcomputer. A buffer(330) outputs the scanning signals(Gout1,Gout2,...,Goutn) at one of a high level(VGH), a low level(VGL), the first supply voltage(VCC), and the second supply voltage(VSS), is applied with the first and second common voltages(Vcom(+),Vcom(-)), and outputs each storage line applying signal(Sout0,Sout1,Sout2,...,Soutn).

Description

In-Plane Switching mode Liquid Crystal Display Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a transverse electric field type liquid crystal display device of a dot inversion method in which power consumption is reduced.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, liquid crystal display devices (LCDs), plasma display panels (PDPs), electro luminescent displays (ELD), and vacuum fluorescent (VFD) Various flat panel display devices such as displays have been studied, and some of them are already used as display devices in various devices.

Among them, LCD is the most widely used as the substitute for CRT (Cathode Ray Tube) for the use of mobile image display device because of the excellent image quality, light weight, thinness, and low power consumption. In addition to the use of the present invention has been developed in various ways such as a television and a computer monitor for receiving and displaying broadcast signals.

In order to use such a liquid crystal display as a general screen display device in various parts, it is a matter of how high quality images such as high definition, high brightness and large area can be realized while maintaining the characteristics of light weight, thinness and low power consumption. Can be.

Currently, an active matrix LCD, in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner, is attracting the most attention due to its excellent resolution and ability to implement video.

Meanwhile, referring to the structure of a general liquid crystal display, it can be seen that the LCD is divided into a liquid crystal panel for displaying an image and a driver for applying a driving signal to the liquid crystal panel. The liquid crystal panel includes first and second substrates bonded to each other with a predetermined space, and a liquid crystal layer injected between the first and second substrates.

Here, the first substrate (first substrate) has a plurality of gate lines arranged in one direction at a predetermined interval, a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines, and the respective gates A plurality of pixel electrodes formed in a matrix form in each pixel region defined by crossing lines and data lines and a plurality of thin film transistors that are switched by signals of the gate lines to transfer signals of the data lines to each pixel electrode are formed. do.

In the second substrate (color filter array substrate), a black matrix layer for blocking light in portions other than the pixel region, an R, G, and B color filter layer for expressing color colors and a common color for implementing an image An electrode is formed.

The first and second substrates are bonded by a seal material having a predetermined space by a spacer and having a liquid crystal injection hole, and a liquid crystal is injected between the two substrates.

In this case, in the liquid crystal injection method, the liquid crystal is injected between the two substrates by osmotic pressure when the liquid crystal injection hole is immersed in the liquid crystal container by maintaining the vacuum state between the two substrates bonded by the reality. When the liquid crystal is injected as described above, the liquid crystal injection hole is sealed with a sealing material.

The driver for applying a signal to the liquid crystal panel is divided into a gate driver for applying a scan signal to a gate line and a source driver for applying a signal to a data line, and each driver is controlled by a microcomputer.

On the other hand, the driving principle of the general liquid crystal display device uses the optical anisotropy and polarization properties of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the arrangement of molecules can be controlled by artificially applying an electric field to the liquid crystal.

Therefore, when light is irradiated to the liquid crystal exhibiting polarization characteristics according to the applied state of the electric field, it is possible to arbitrarily adjust the molecular alignment direction of the liquid crystal, the amount of light passing according to the alignment state of the liquid crystal can be adjusted to represent the image information have.

As described above, a general liquid crystal display device in which a pixel electrode is formed on a first substrate and a common electrode is formed on a second substrate, and a liquid crystal is driven by an electric field applied up and down has a disadvantage in that viewing angle characteristics are not excellent. In order to overcome such disadvantages, an in-plane switching mode (IPS mode) liquid crystal display device that forms a horizontal electric field to drive a liquid crystal has been proposed.

An advantage of the transverse electric field type liquid crystal display device is that a wide viewing angle is possible. That is, when the liquid crystal display device is viewed from the front, the liquid crystal display device may be visible in the up / down / left / right directions at about 70 °. In addition, the manufacturing process is simpler than the TN mode liquid crystal display device generally used, and there is an advantage that the color shift according to the viewing angle is small.

Hereinafter, a conventional transverse electric field type liquid crystal display device will be described with reference to the accompanying drawings.

1 is a schematic cross-sectional view illustrating a general transverse electric field type liquid crystal display device.

As shown in FIG. 1, a general transverse electric field type liquid crystal display device includes a first substrate 1, a second substrate 2 opposing thereto, and a liquid crystal layer 3 filled therebetween.

Here, the first substrate 1 has a TFT (thin film transistor) array formed on the substrate 10 in a matrix form, and although not shown, the drain electrode and the pixel electrode 20 of the thin film transistor are connected to each other. The common electrode 30 is formed to be spaced apart from the pixel electrode 20 by a predetermined interval.

In addition, although not shown, a black matrix layer covering a region other than the pixel and a color filter layer implementing color colors are formed on the second substrate 2 facing the first substrate 1.

As described above, in the transverse electric field type liquid crystal display, both the pixel electrode 20 and the common electrode 30 exist on the same plane, and the liquid crystal is driven by a horizontal electric field formed between the two electrodes.

Meanwhile, a driving method of such a general transverse electric field type liquid crystal display device will be described.

A general liquid crystal display device including a transverse electric field type liquid crystal display device adopts a method in which an image signal is applied to a pixel corresponding to a line when each pixel is arranged in a matrix form and a scan signal is input to one gate line.

However, since the deterioration of characteristics occurs when the DC voltage is applied for a long time, the liquid crystal injected between the first and second substrates is driven by periodically changing the polarity of the applied voltage, and this method is called a polarity inversion method. .

The polarity inversion scheme includes frame inversion, line inversion, column inversion, and dot inversion.

In the frame inversion method, the polarity of the data voltage applied to the liquid crystal with respect to the common electrode voltage is applied in the same frame unit. That is, if a data voltage of positive polarity is applied to an even frame, a data voltage of negative polarity is applied to an odd frame. However, such a frame inversion driving method has the advantage of low current consumption during switching, but is sensitive to flicker caused by the asymmetry of transmittance between the positive and negative polarity, and crosstalk due to inter-data interference ( It is very vulnerable to crosstalk.

In addition, the line inversion method is a polarity inversion driving method which is generally used for low resolution (VGA, SVGA), and the data voltage is applied so that the polarity of the data voltage applied to the liquid crystal with respect to the common electrode voltage varies in units of horizontal lines. do. That is, if a positive polarity is applied to an odd gate line and a negative polarity data voltage is applied to an odd gate line, a negative data voltage is applied to an odd gate line in a next frame. In addition, a data voltage of positive polarity is applied to the even-numbered gate line. In this line inversion method, since data voltages of opposite polarities between adjacent lines are applied, the luminance variation between lines decreases the flicker phenomenon compared to the frame inversion by spatial averaging, and voltages of opposite polarities are distributed in the vertical direction. Therefore, the coupling phenomenon between the data is canceled out so that the vertical crosstalk compared to the frame inversion is small. However, in the horizontal direction, voltages of the same polarity are distributed to generate horizontal crosstalk, and the number of switching repetitions is increased compared to frame inversion, thereby increasing current consumption.

The thermal inversion method is a driving method in which the polarities of the data voltages applied to the liquid crystal with respect to the common electrode voltage are the same in the vertical direction and are opposite in the horizontal direction. Compared with the frame reversal method, the flicker phenomenon is smaller than the frame reversal method and the horizontal crosstalk is smaller than the frame reversal method. However, since a data voltage of opposite polarity between adjacent lines must be applied in a vertical direction with respect to the common electrode voltage, a high voltage column drive IC must be used.

Finally, the dot inversion method is a polarity inversion driving method that realizes the best image quality at present, and is applied to high resolutions (XGA, SXGA, and UXGA), and polarities of data voltages between adjacent pixels are reversed in all directions. Therefore, the flicker phenomenon can be minimized by the spatial averaging method, but it has the disadvantage of using a high voltage source driver and having a large current consumption.

Hereinafter, the conventional transverse electric field type liquid crystal display device which takes a dot inversion drive system is demonstrated.

2 is a layout diagram illustrating a pixel structure of a conventional transverse electric field type liquid crystal display device, FIG. 3 is a cross-sectional view of a structure on a line A-A 'of FIG. 2, and FIG. 4 is a cross-sectional view of a structure on a line B-B' of FIG. 2. .

As shown in FIG. 2, a conventional transverse electric field type liquid crystal display device includes a plurality of gate lines 40 and a plurality of data lines 50 formed in a horizontal direction and a vertical direction to define a pixel area, respectively, and the plurality of gates 40. ) A plurality of storage lines 60 formed at a predetermined interval apart from each other, a plurality of thin film transistors (TFTs) formed at intersections of the plurality of gate lines 40 and the plurality of data lines 50, and the plurality of lines A pixel electrode 20 connected to a drain electrode of each of the TFTs and formed in a pixel region in a '|' shape, and spaced apart from the pixel electrode 20 in the pixel region by a predetermined distance, ) And a common electrode 30 formed in a '영역' shape in the pixel area.

Hereinafter, a method of forming a conventional transverse electric field type liquid crystal display device will be described with reference to FIGS. 3 to 4.

First, the metal is entirely deposited on the substrate 10 and selectively removed, thereby horizontally separating the gate line 40 protruding from the gate electrode and a storage line spaced apart from each other in the same direction as the gate line 40. 60).

Subsequently, a gate insulating layer 25 is formed on the entire surface of the substrate 10 including the gate line 40 and the storage line 60.

Next, a semiconductor layer (not shown) is formed on the gate insulating layer 25 to correspond to the gate electrode.

Subsequently, a metal is entirely deposited on a predetermined region on the gate insulating layer 25 and selectively removed to form a data line 50 and a source / drain electrode 50c in a direction perpendicular to the gate line 40. In this case, a thin film transistor TFT formed of the gate electrode, the semiconductor layer, and the source / drain electrodes 50c is formed.

Subsequently, a passivation layer 35 is formed on the entire surface of the substrate 10 including the data line 50.

Subsequently, contact holes are formed in the drain electrode 50c of the thin film transistor TFT and a predetermined portion of the storage line 60, and a metal is entirely deposited on the passivation layer 35 and patterned to form a contact hole. The pixel electrode 20 connected to the drain electrode 50c of the TFT and the common electrode 30 connected to the storage line 60 are formed to be spaced apart from the pixel electrode 20 by a predetermined interval.

As described above, the common electrode 30 is in contact with the storage line 60 formed at the bottom thereof to receive power, and the pixel electrode 20 is applied with a data voltage by an on / off operation of the thin film transistor TFT. . Here, the storage lines 60 are connected to one from the outside to apply the same common voltage Vcom signal, and the common voltage Vcom signal is in a DC state.

5 is an equivalent circuit diagram of FIG. 2, and FIG. 6 is a timing diagram illustrating pixel voltages of respective gate lines of FIG. 2.

As shown in FIG. 5, each pixel of a conventional transverse field type liquid crystal display device includes a storage capacitor between a drain electrode of the thin film transistor TFT formed between the gate line 40 and the data line 50 and the storage line 60. It can be seen that (Cst) and the liquid crystal capacitor (Clc) are formed in parallel.

As shown in FIG. 6, the common voltage Vcom signal is maintained at a predetermined level even when the pixel, the gate line 40, or the frame is changed. At this time, the predetermined level state is an intermediate level between voltages of two levels applied to the data line. The voltage applied to the data line is inverted in one horizontal period and applied. The data lines crossing each gate line have different polarities in each pixel so as to have a positive polarity or a negative polarity based on the common voltage. Apply the data voltage.

At this time, odd-numbered data lines apply odd-numbered data lines, and even-numbered data lines apply voltage signals having the same level as even-numbered data lines.

The gate driver (not shown) applies a selection pulse through the gate line to drive the pixels corresponding to the same line, and the source driver (not shown) applies an image signal to the thin film transistor turned on through the signal line. When a data voltage is applied through the turned on thin film transistor, the liquid crystal capacitor Clc and the storage capacitor Cst connected between the drain electrode and the storage line of the thin film transistor are charged while the thin film transistor is turned on. When the transistor is turned off, the charge charge is maintained until the thin film transistor is subsequently turned on.

Referring to FIG. 6, the pixel voltage fluctuates as much as ΔVp due to a parasitic capacitor Cgs formed between the gate electrode and the source electrode of the thin film transistor at the falling edge of the scan signal applied to the gate line. The pixel voltage is derived by a value separated by ΔVp.

FIG. 7 is a view illustrating polarity change of common voltage for each pixel of each conventional transverse electric field type liquid crystal display for each odd frame / even frame.

As illustrated in FIG. 7, a conventional transverse electric field type liquid crystal display device driven by a dot inversion method has different polarities (data voltages for common voltages) in adjacent pixels, and each time the frame is changed, the polarity of each pixel is inverted. do.

In this case, the polarities of the charges charged to the adjacent pixels are different from each other by (+), (-), ..., etc. of the polarities of the charges charged to each pixel, so that a high quality image can be obtained at high speed. have.

FIG. 8 is a block diagram illustrating the inside of a gate driver of a conventional transverse electric field liquid crystal display, and FIG. 9 is a timing diagram illustrating a TCP structure of a gate driver of a conventional transverse electric field type liquid crystal display and changes in input and output signals in the TCP structure. .

As shown in FIG. 8, a gate driver of a conventional transverse electric field type liquid crystal display includes a gate start pulse signal (GSP), a gate shift clock signal (GSC), a left and right selection signal from a microcomputer (not shown). A shift register 61 sequentially operated by receiving L / R: Left / Right Select, a level shifter 62 sequentially shifting by receiving a gate output enable signal (GOE: Gate Output Enable) from a microcomputer, And a buffer 63 for outputting the gate line signals Gout 1, Gout 2, ..., Gout n for selectively applying one of the VGH, VGL, VCC, and VSS levels to each gate line. .

An operation of the gate driver will be described with reference to FIG. 9 as follows.

First, the shift register 61 shifts the gate start pulse signal GSP by the gate shift clock signal GSC to sequentially enable the gate lines. Finally, after the enable operation of the gate lines of one frame is completed, a carry value is sent, and then the operation of the gate lines of the next frame is transferred.

Subsequently, the level shifter 62 sequentially shifts a signal applied to the gate line and outputs the signal to the buffer 63.

Therefore, the plurality of gate lines connected to the buffer 63 are sequentially enabled. At this time, the predetermined gate line maintains the VGH level in synchronization with the gate shift clock signal GSC, and then falls to the VGL level at the rising edge of the gate output enable signal GOE.

As described above, the driving method of the conventional transverse electric field type liquid crystal display including the configured gate driver is as follows.

First, the source driver (not shown) sequentially receives image data of one pixel from the microcomputer and stores the image data corresponding to the data lines.

The gate driver outputs a gate shift clock signal GSC, a gate shift pulse signal GSC, and a gate output enable signal GOE to sequentially apply a scan signal to the plurality of gate lines.

Accordingly, the plurality of thin film transistors connected to the selected gate line are turned on and the image data (data voltage form) stored in the shift register of the source driver is applied to the drain electrode, thereby displaying the image data on the liquid crystal panel. Thereafter, the above operation is repeated to display the image data on the liquid crystal panel.

In this case, a pin for outputting a gate line signal applied to each gate line is sequentially configured from the first gate line pin to the nth gate line pin on the output side of the gate driver Tape Carrier Package (TCP).

However, the conventional transverse electric field type liquid crystal display device has the following problems.

When driving the conventional transverse type liquid crystal display device by the dot inversion method, a common voltage signal is applied with a constant value of DC, and the data voltage applied to the data line has polarities (+) and (−) based on the common voltage signal. ) Alternately to apply voltage.

Since the pixel voltage applied to the liquid crystal has a polarity depending on the data voltage, a source driver having a high output voltage difference must be used in order to form a high voltage in the liquid crystal.

A source driver of a transverse field type liquid crystal display device which is generally applied at present has an output range using a VDD power supply of about 15V. In this case, the pixel voltage actually applied to the liquid crystal is about (−) 6V to (+) 6V.

However, since the cost is higher for the source driver of the high output range, efforts have been made to reduce the cost by inducing low power consumption to lower the output range.

On the other hand, in the transverse type liquid crystal display device, the liquid crystal is driven by a fringe field formed between the common electrode and the pixel electrode, so that the gap between the pixel electrode and the common electrode is narrowed between the two electrodes for smooth driving of the liquid crystal. The fringe field to be derived should be formed with a large value.

In order to narrow the gap between the pixel electrode and the common electrode, when forming a pattern of the pixel electrode and the common electrode, a single line-type pixel electrode and a common electrode are not formed, but fingers that intersect and intersect at a predetermined interval apart from each other. The pixel electrode and the common electrode pattern having a fin form are formed. In this case, the gap between the pixel electrode and the common electrode is narrowed, but the aperture ratio of the pixel is lowered.

Of course, although the ITO or the like of the transparent material is mainly used as the pattern of the pixel electrode or the common electrode, various shapes of patterns are formed in the pixel area, thereby preventing light from being evenly transmitted.

In this case, when the distance between the pixel electrode and the common electrode is increased for the high opening ratio, the horizontal electric field formed between the two electrodes becomes small, so that a data voltage of a high output range is required to obtain the required luminance.

An object of the present invention is to provide a transverse electric field type liquid crystal display device of a dot reversal method in which power consumption is reduced to solve the above problems.

1 is a schematic cross-sectional view showing a general transverse electric field type liquid crystal display device

2 is a layout diagram illustrating a pixel structure of a conventional transverse electric field type liquid crystal display device;

3 is a cross-sectional view of a structure on the line AA ′ of FIG. 2.

4 is a structural cross-sectional view taken along the line BB ′ of FIG. 2.

5 is a simplified equivalent circuit diagram of the pixel structure of FIG.

FIG. 6 is a timing diagram illustrating pixel voltages of voltage signals applied to the gate lines and the storage lines of FIG. 2. FIG.

FIG. 7 is a diagram illustrating polarity variation of common voltages for each pixel of a conventional transverse electric field type liquid crystal display for each odd frame / even frame. FIG.

8 is a block diagram illustrating the inside of a gate driver of a conventional transverse electric field type liquid crystal display device.

9 is a timing diagram showing a TCP structure of a gate driver of a conventional transverse electric field type liquid crystal display and a change of input and output signals in the TCP structure;

FIG. 10 is a timing diagram illustrating pixel voltages of voltage signals applied to respective gate lines and storage lines of a transverse electric field type liquid crystal display device according to an exemplary embodiment of the present invention. FIG.

11 is a block diagram showing a gate driver of the transverse electric field type liquid crystal display device of the present invention.

12 is a diagram illustrating a signal configuration of an input / output side of TCP including the gate driver of FIG. 11;

FIG. 13 is a view illustrating a connection state of a TCP bonding pad unit of FIG. 12 and a panel connected thereto; FIG.

14 is a layout diagram illustrating a pixel structure of a transverse electric field type liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 15 is a cross-sectional view of a structure on the line C ~ C 'of FIG.

FIG. 16 is a cross-sectional view of the structure taken along the line D-D 'of FIG.

17 is a layout diagram illustrating a pixel structure of a transverse electric field type liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 18 is a structural cross-sectional view taken along the line E-E 'of FIG.

FIG. 19 is a structural cross-sectional view taken along the line FF ′ of FIG. 17.

20 is an equivalent circuit diagram of a transverse electric field type liquid crystal display device of the present invention.

FIG. 21 is a view illustrating polarity change of each pixel of each transverse field type liquid crystal display device according to an odd frame / even frame.

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

200: substrate 210: gate line

215: gate insulating film 220: data line

220c: drain electrode 225: protective film

230: pixel electrode 240: common electrode

250: storage line 310: shift register

320: level shifter 330: buffer

TFT: thin film transistor

In an aspect of the present invention, a transverse electric field type liquid crystal display device includes a plurality of gate lines and data lines vertically intersecting to define a pixel region, and a plurality of gate lines and data lines alternately formed in upper and lower pixel regions of each gate line. A transverse field type liquid crystal display device comprising a thin film transistor and a plurality of storage lines each formed in a zigzag form along each thin film transistor formed in the same line pixel region to apply a common voltage, wherein the odd-numbered and even-numbered The storage line may further include a gate driver configured to apply first and second common voltages Vcom (+) / Vcom (−), respectively.

The gate driver receives a gate start pulse signal from a microcomputer and sequentially stores a scan signal to be applied to each gate line in synchronization with a gate shift clock signal, and the scan signal in response to a gate output enable signal from the microcomputer. Outputs a scan signal at a predetermined level among four levels of a level shifter for shifting the voltage shifter, a high level VGH, a low level VGL, a first power supply voltage VCC, and a second power supply voltage VSS. It is preferable that the first and second common voltages Vcom (+) and Vcom (−) are applied to alternately output buffers for outputting respective storage line application signals.

In the TCP output terminal of the gate driver, a storage line signal application pin is further configured between the gate line signal application pins for applying the signal of each gate line of the panel. The gate driver TCP output terminal may further include a dummy line applying pin at an uppermost side and a lowermost side of the gate line signal applying pin.

When the scan signal is applied to each gate line, first and second common voltages Vcom (+) and Vcom (−) of high and low levels are alternately applied to the storage lines corresponding to the gate lines, respectively. desirable.

Preferably, the first and second common voltages Vcom (+) and Vcom (−) are high and low level voltage signals, respectively.

Preferably, a data voltage having a polarity of (−) / (+) is applied to a data line which meets the gate line to which the scan signal is applied, with respect to a first or second common voltage applied to a corresponding storage line.

Preferably, the first common voltage applied to each of the storage lines is changed to a second common voltage at frame inversion, and the second common voltage is changed to a first common switch at frame conversion.

Preferably, the data voltage applied to each of the data lines inverts the data voltage of the previous frame in one vertical period.

The output value of the pixel voltage applied to the liquid crystal may be adjusted by a voltage difference between the first or second common voltage applied to the storage line and the data voltage applied to the data line.

Hereinafter, the transverse electric field type liquid crystal display of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 10 is a timing diagram illustrating pixel voltages of voltage signals applied to respective gate lines and storage lines of the transverse electric field type liquid crystal display device of the present invention.

The transverse electric field type liquid crystal display device of the present invention is a liquid crystal display device in which a common electrode and a pixel electrode are disposed on the same plane to form a transverse electric field. As shown in FIG. 10, a scan signal applied to a gate line and a common voltage applied to a storage line The pixel voltage value is affected by the signal.

In this case, the common voltage signal applied to the storage line may be divided into odd-numbered and even-numbered lines, respectively, and may have different levels with the first common voltage Vcom (+) and the second common voltage Vcom (-). Is approved. Here, the first common voltage Vcom (+) is at a high level, and the second common voltage Vcom (−) is at a low level.

In this case, the data voltage applied to the data line crossing the gate line is the pixel voltage when the common voltage applied to the storage line is high level, that is, the first common voltage Vcom (+). The data voltage is applied to have a polarity, and when the second common voltage Vcom (−) is applied, the data voltage is applied to have a positive polarity.

The voltages applied to each of the storage lines and the data lines maintain a predetermined state for one vertical period and are inverted.

In this case, the pixel voltage of each pixel is the difference between the data voltage and the common voltage, and the magnitude of the pixel voltage is the difference between the first and second common voltages Vcom (+) and Vcom (-) (Vcom (+). ) -Vcom (-)) Therefore, in order to maintain a constant polarity at all times in the related art, a data voltage has to be applied with a voltage difference greater than or equal to a predetermined value from the common voltage in order for each pixel to have a stable polarity. By setting the common voltage differently according to the polarity of the pixel, the margin of the applied data voltage can be increased. Therefore, the output width of the source driver applying the data voltage to the data line can be reduced.

11 is a block diagram illustrating a gate driver of a transverse electric field type liquid crystal display device of the present invention.

As shown in FIG. 11, the gate driver of the transverse electric field liquid crystal display according to the present invention receives the gate start pulse signal GSP and the left and right selection signals L / R from a microcomputer (not shown). A shift register 310 for sequentially storing scan signals Gout 1, Gout 2, ..., Gout n to be applied to each gate line in synchronization with (GSC), and a gate output enable signal GOE from the microcomputer A level shifter 320 for shifting the scan signals Gout 1, Gout 2,..., Gout n, a high level VGH, a low level VGL, a first power voltage VCC, The scan signals Gout 1, Gout 2,..., Gout n are output at a predetermined level among the four levels of the second power supply voltage VSS, and the preset first and second common voltages Vcom (+), Vcom (-)) is applied to the buffer 330 to alternately output each storage line applying signal (Sout 0, Sout 1, Sout 2, ...., Sout n) Lose.

FIG. 12 is a diagram illustrating a signal configuration of an input / output side of TCP including the gate driver of FIG. 11.

An operation of the gate driver will now be described with reference to FIGS. 11 and 12.

First, the shift register 310 shifts the gate start pulse signal GSP by the gate shift clock signal GSC to enable the gate lines sequentially. Finally, after the enable operation of the gate lines of one frame is completed, a carry signal Carry is sent, and then the operation of the gate lines of the next frame is performed.

Subsequently, the level shifter 320 sequentially level shifts a signal applied to the gate line and outputs the signal to the buffer 330.

Therefore, the plurality of gate lines connected to the buffer 330 are sequentially enabled. At this time, the predetermined gate line maintains the VGH level in synchronization with the gate shift clock signal GSC, and then falls to the VGL level at the rising edge of the gate output enable signal GOE.

The operation of the gate driver described above is an operation when the right selection signal R is applied, and when the left selection signal L is applied, the signals are applied to the respective gate lines and the storage lines in the reverse order as described above. do.

As described above, the driving method of the transverse electric field type liquid crystal display device of the present invention including the configured gate driver is as follows.

First, the source driver (not shown) sequentially receives image data of one pixel from the microcomputer and stores the image data corresponding to the data lines.

The gate driver outputs the gate shift clock signal GSC, the gate start pulse signal GSP, and the gate output enable signal GOE, and sequentially applies a scan signal to the plurality of gate lines.

Accordingly, the plurality of thin film transistors connected to the selected gate line are turned on and the image data (data voltage form) stored in the shift register of the source driver is applied to the drain electrode, thereby displaying the image data on the liquid crystal panel. Thereafter, the above operation is repeated to display the image data on the liquid crystal panel.

FIG. 13 is a diagram illustrating a connection state of a TCP bonding pad unit of FIG. 12 and a panel connected thereto.

As shown in FIG. 13, the gate driver is configured in TCP, and the TCP is disposed around the liquid crystal panel to apply a scan signal to the gate line configured in the liquid crystal panel. In this case, a storage line is formed between the gate lines in the liquid crystal panel corresponding to each gate line, and a driver for applying a signal to each of the gate lines and the storage line is located in the gate driver.

At this time, the output side of the gate driver is located in the TCP bonding pad portion, and the storage line signal applying pins corresponding to the storage line are intersected between each gate line signal applying pin and the gate line signal applying pin. have.

Hereinafter, the pixel structure of the liquid crystal panel operating by receiving signals from the gate driver and the source driver (not shown) will be described.

FIG. 14 is a layout diagram illustrating a pixel structure of a transverse electric field type liquid crystal display according to an exemplary embodiment of the present invention, FIG. 15 is a cross-sectional view of a structure on the line C ′ of FIG. 14, and FIG. 16 is a line D ′ of FIG. It is a structural cross section on a line.

As shown in FIGS. 14 to 16, a pixel structure of a transverse electric field type liquid crystal display according to an exemplary embodiment of the present invention is formed in a horizontal direction and a vertical direction, respectively, to define a plurality of gate lines 210 and a plurality of data. A plurality of thin film transistors (TFTs) alternately formed up and down the gate line 210 with respect to an adjacent pixel, and a drain electrode 220c of each of the thin film transistors TFTs. A plurality of pixel electrodes 230 formed in a region, a plurality of common electrodes 240 formed in the pixel region spaced apart from each pixel electrode 230 by a predetermined interval, and the plurality of thin film transistors TFT are formed. It includes a plurality of storage lines 250 formed in a continuous form of 'L' lying in the pixel area formed on the same line along the portion.

In this case, the common electrode 240 adjacent to the right data line 220 of the pixel area overlaps with the storage line 250 formed at the bottom, and crosses the right data line so that the storage line 250 is next to the next pixel area. Is connected. In this case, the pattern of the storage line 250 to be connected extends the storage line 250 formed along the thin film transistor TFT formed in the next pixel area toward the previous pixel area and thus the right data line 220. By overlapping with the adjacent common electrode 240, a storage line is connected between adjacent pixel areas.

17 is a layout diagram illustrating a pixel structure of a transverse electric field type liquid crystal display according to another exemplary embodiment of the present invention, FIG. 18 is a cross-sectional view of the structure on the line E-E 'of FIG. 17, and FIG. 19 is a line F-F of FIG. 17. 'Structure cross section on line.

17 to 19, a pixel structure of a transverse electric field type liquid crystal display device according to another exemplary embodiment of the present invention is formed in a horizontal direction and a vertical direction, respectively, to define a plurality of gate lines 210 and a plurality of data. A plurality of thin film transistors (TFTs) alternately formed up and down the gate line 210 with respect to an adjacent pixel area, and a drain electrode of each of the thin film transistors TFTs, A plurality of pixel electrodes 230 formed, a plurality of common electrodes 240 formed in the pixel region by crossing the pixel electrodes 230 at predetermined intervals, and the plurality of thin film transistors TFTs are formed It includes a plurality of storage lines 250 formed in an inverted form of the 'r' type lying in the pixel areas formed on the same line along the portion.

In this case, the common electrode 240 adjacent to the left data line 220 of the pixel area overlaps with the storage line 250 formed at the bottom, and crosses the left data line 220 so that the storage line 250 Before and after are connected in the pixel region. In this case, the pattern of the storage line 250 to be connected extends the storage line formed to be parallel to the gate line 210 along the thin film transistor TFT formed in the previous pixel area. It is formed so as to overlap the common electrode 240 in the next pixel region.

The second exemplary embodiment described above has the same structure as the first exemplary embodiment except that the portion where the storage line 250 overlaps the common electrode 240 is a common electrode adjacent to the left data line of the pixel area. If so, the same number was given.

Meanwhile, the idea of the present invention is to zigzag in pixel regions formed on the same line along a plurality of thin film transistors (TFTs) formed alternately up and down the gate lines, including the first and second embodiments described above. It can be extended in various ways of a transverse electric field type liquid crystal display device in which a storage line is formed to be connected.

A method of forming the pixel structure of the transverse electric field type liquid crystal display device according to the present invention described above is as follows.

First, the metal is entirely deposited on the substrate 200 and selectively removed to form the storage line 250 in a horizontal direction, spaced apart from the gate line 210 where the gate electrode protrudes. In this case, the gate electrodes of the gate lines 210 are formed in different directions up and down with respect to adjacent pixel areas. In addition, the storage line 250 formed at this time is formed in a zigzag manner so as to overlap the portion where the drain electrode and the common electrode formed in a later process are spaced apart from the gate line 210 by a predetermined interval. do.

Subsequently, a gate insulating layer 215 is formed on the entire surface of the substrate 200 including the gate line 210 and the storage line 250.

Subsequently, a semiconductor layer (not shown) is formed on the gate insulating layer 215 to correspond to the gate electrode.

Subsequently, metal is entirely deposited on a predetermined region on the gate insulating layer 215 and selectively removed to form a data line 220 and a source / drain electrode 220c in a direction perpendicular to the gate line 210. In this case, a thin film transistor TFT including the gate electrode, the semiconductor layer, and the source / drain electrodes 220c is formed.

Subsequently, a passivation layer 225 is formed on the entire surface of the substrate 200 including the data line 220.

Subsequently, after the metal is entirely deposited on the passivation layer 225, the storage line is spaced apart from the pixel electrode 230 and the pixel electrode 230 which are connected to the drain electrode 220c of the thin film transistor TFT. The common electrode 240 connected to the 250 is formed.

In this case, a gate insulating film is interposed between the drain electrode 220c and the storage line 250 of the thin film transistor TFT to form a storage capacitor Cst (not shown) and a liquid crystal capacitor Clc (not shown). ).

The common electrode 240 and the storage line 250 are formed to have a contact in a predetermined region of the overlapped portion.

20 is an equivalent circuit diagram of a transverse electric field type liquid crystal display device of the present invention.

As shown in FIG. 20, when the pixel structure of FIG. 14 or 17 is represented by an equivalent circuit, each storage line may be illustrated as being located between adjacent gate lines.

That is, the pixel structure of the transverse field type liquid crystal display device according to the present invention includes a plurality of gate lines and a plurality of data lines that vertically intersect. And an nth storage line formed between the nth (n ≧ 1) gate line and the n + 1th gate line, a first thin film transistor connected to the nth + 1th gate line and the mth data line, A second thin film formed at an intersection of the first storage capacitor and the first liquid crystal capacitor formed in parallel between the drain electrode of the first thin film transistor and the nth storage line, and the nth gate line and the m + 1th data line And a second storage capacitor and a second liquid crystal capacitor formed in parallel between the transistor, the drain electrode of the second thin film transistor, and the storage line.

In this case, the storage line is an odd-numbered storage line and the odd-numbered storage lines are applied with a first common voltage (or a second common voltage), and the even-numbered storage line is even-numbered storage lines with a second common voltage (or first common). Voltage) is applied. In this case, pixel voltages having the same polarity are applied to pixels connected to the same storage line.

FIG. 21 is a view illustrating polarity change of common voltage for each pixel of each transverse field type liquid crystal display device according to an odd frame / even frame.

If the first and second common voltages having different levels are applied to each storage line, and each line is divided into the same storage lines as shown in FIG. 21, pixel voltages having the same polarity are generated in pixels formed on the same storage line. In contrast, adjacent storage lines have opposite polarities.

Accordingly, in the transverse electric field type liquid crystal display device of the present invention, a signal is applied to the liquid crystal panel side in a dot reversal manner from a gate driver and a general source driver applying different levels of common voltage, respectively, to maintain fast signal response characteristics, and also to store The line is driven by a line inversion method so that the distortion of the electric field of adjacent pixels is less affected. In particular, the electro-optical characteristics such as black luminance are good.

The above-described transverse electric field type liquid crystal display of the present invention has the following effects.

First, power consumption can be reduced by reducing the variation range of the source driver's output voltage. A higher pixel voltage can be applied to the liquid crystal by using a gate driver that applies different common voltages to adjacent storage lines together with a source driver having a data output signal polarity as in the dot inversion method.

Second, the pixel voltage value can be increased compared to the output voltage of the same source driver as compared with the related art, thereby enabling a high-aperture structure to increase the distance between the pixel electrode and the common electrode, and improve luminance.

Third, the output voltage of the source driver is simultaneously outputted with the opposite polarity in the same way as the general dot inversion method, whereas the pixel voltages of the same polarity are arranged in the actual gate line direction, so that electric fields of adjacent pixels are arranged. The distortion is less affected by the electro-optical properties, especially black brightness.

Fourth, since a source driver / gate driver of a general dot inversion driving method is used as it is, high quality with small vertical and horizontal crosstalks can be realized as compared with other inversion methods.

Claims (11)

A plurality of gate lines and data lines vertically intersecting to define pixel regions, a plurality of thin film transistors alternately formed in upper and lower pixel regions of each gate line, and a plurality of thin film transistors formed in the same line pixel region to apply a common voltage In a transverse field type liquid crystal display device including a plurality of storage lines formed in a zigzag form along each thin film transistor, And a gate driver applying first and second common voltages (Vcom (+) / Vcom (-)) to odd-numbered and even-numbered storage lines, respectively. The method of claim 1, The gate driver A shift register receiving a gate start pulse signal from a microcomputer and sequentially storing scan signals to be applied to each gate line in synchronization with the gate shift clock signal; A level shifter shifting the scan signal in response to a gate output enable signal from the micom; The scan signal is output at a predetermined level among four levels of the high level VGH, the low level VGL, the first power supply voltage VCC, and the second power supply voltage VSS, and the predetermined first and second common voltages ( A transflective liquid crystal display device comprising: a buffer configured to receive Vcom (+) and Vcom (-)) and alternately output a signal for applying each storage line. The method of claim 2, And a bilateral shift function by applying a left and right selection signal to the shift register. The method of claim 1, And a storage line signal applying pin is further formed at the TCP output terminal of the gate driver between each gate line signal application pin for applying a signal of each gate line of the panel. The method of claim 4, wherein And a dummy line applying pin is further formed on the gate driver TCP output terminal at an uppermost side and a lowermost side of the gate line signal applying pin. The method of claim 1, When the scan signal is applied to each gate line, first and second common voltages Vcom (+) and Vcom (−) of high and low levels are alternately applied to the storage lines corresponding to the gate lines, respectively. Transverse electric field type liquid crystal display device. The method of claim 1, The first and second common voltages Vcom (+) and Vcom (-) are high level and low level voltage signals, respectively. The method of claim 6, A data voltage having a polarity of (−) / (+) is applied to a data line that meets the gate line to which the scan signal is applied, to a first or second common voltage applied to a corresponding storage line, respectively Electric field liquid crystal display device. The method of claim 8, And a first common voltage applied to each of the storage lines is a second common voltage when the frame is inverted, and a second common voltage is changed to the first common voltage when the frame is converted. The method of claim 8, And a data voltage applied to each of the data lines inverts the data voltages of all the frames by one vertical period. The method of claim 1, And an output value of the pixel voltage applied to the liquid crystal by a voltage difference between the first or second common voltage applied to the storage line and the data voltage applied to the data line.