JP3031295B2 - Active matrix type liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an IPS (In Plane Switch).
g) Mode active matrix type liquid crystal display device.

[0001]

2. Description of the Related Art The structure of a conventional general active matrix type liquid crystal display device will be described with reference to FIG. In a conventional active matrix liquid crystal display device, pixels arranged in a matrix are driven using the same number of gate lines and data lines as the rows and columns. For example, 640 pixels each for RGB in the horizontal direction and 480 pixels in the vertical direction
VGA (Video Graphics) having pixels
An active matrix liquid crystal display device for color display of the (Array) system requires 480 gate lines 801 for a pixel selection signal and 640 × 3 data lines 802 for transmitting a signal voltage held in each pixel. . Further, a thin film transistor (TFT) 804 is provided at an intersection of each gate line 801 and data line 802, and a pixel 803 is connected through the thin film transistor (TFT) 804. Those gate lines 801
To drive the data lines 802, the same number of scanning line drivers 805 and signal line drivers 806 are required. In the case of displaying multiple gradations, digital driving is generally used. In that case, the signal line driver 806 has 6 bi
When the resolution is t, the polarity inversion drive is considered as 128.
Since it is necessary to output a voltage of a level, the scanning line driver 8 merely outputs a selection pulse to the gate line sequentially.
05, which is considerably expensive, and has the problem of increasing costs.

[0002] In addition, the liquid crystal display device has many portable uses,
Low power consumption is required, and the power consumption of a liquid crystal display device is larger than that of a scanning line driver that sends a pulse to only one of the gate lines, and the number of signal line drivers that operate in parallel is large. The power consumption is incomparably high, and it is necessary to reduce the power consumption of these data lines and signal drivers.

[0003] To solve these problems of cost and power consumption, Japanese Patent Application Laid-Open No. 3-38689 and Japanese Patent Application Laid-Open No. 5-26 are proposed.
5045, there is an active matrix type liquid crystal display device disclosed in JP-A-6-148680.
(Hereinafter referred to as Conventional Example 1 or double speed driving method). FIG. 9A is a plan view showing a pixel arrangement of four columns and two rows, and FIG. 9B is a diagram for explaining a driving method thereof. For example, in the above-described VGA type color liquid crystal display, 960 gate lines 901 and 902 and two 960 gate lines 901 and 902 are assigned to one display line in the scanning direction to display pixels of 480 rows × 1920 columns. 960
It has three data lines 903 and 904, and each data line 903
One of the gate lines 9 disposed on the left side of the
01 is driven through the first thin film transistor connected to the first thin film transistor, and is driven through the second thin film transistor connected to the other gate line 901 disposed to the right of the data line and below the data line. 906.

FIG. 9B is a diagram for explaining a method of driving these pixels. The horizontal scanning period 915 is divided into two, a first scanning period 916 and a second scanning period 917. At 916, one pixel 905 disposed on one side of the data line 903 is driven, and during the second scanning period 917, the scanning line and the data line are driven at twice the speed of the related art so as to drive the other pixel 906. Things. The order of writing to the pixels is performed, for example, as follows. The pixels connected to the data line 903 are written in the order of the pixels 905 → 906 → 907 → 908 in the order of the gate lines, and the pixels connected to the data line 904 are similarly written in the pixels 909 → 910 → 912. → Write in the order of 911.

As described above, it is said that the number of data lines and the number of signal drivers can be halved, and the cost and power consumption can be reduced according to the pixel array configuration and the driving method of Conventional Example 1.

However, the driving method of the conventional example 1 has the following problems. As described above, a signal is written to the first pixel 905 in the first scanning period 916 and a signal is written to the second pixels 906 and 910 in the second scanning period 917. At this time, the first pixel 905 At the time of writing to the pixels 906 and 910, the parasitic capacitance C1 between the pixels 905 and 906 and the parasitic capacitance C2 between the pixels 905 and 910.
Subject to fluctuations. Assuming that the total capacitance of the pixel is Ctot and the amplitude of the data signal is VD, the fluctuating voltage Vpp918 becomes Vpp = (C1−C2) / Ctot * VD. Since there is a data line between the pixel 905 and the pixel 906, but there is no potential line between the pixel 905 and the pixel 910, generally, C2 is much larger than C1, the interval between the pixels 905 and 906, and the pixel 905 and the pixel 910 interval is 1
If it is about 0 μm, it will be about Vpp to 300 mV.

Therefore, the first pixel 905 and the second pixel 90
6,910 generally has a voltage difference of about 300 mV, and when displaying a halftone or the like, the brightness of the pixels is not constant,
There was a problem that the display quality deteriorated. In addition, in order to prevent such display quality deterioration, it is necessary to increase the pixel interval,
There is a problem that the light transmission area is reduced.

Although description has been omitted in the above example, the proposal of these driving methods is to apply an electric field between the opposing substrates and to set the direction of the molecular axis of the aligned liquid crystal molecules (hereinafter referred to as director) to the substrates. The present invention relates to a TN (Twisted Nematic) mode liquid crystal display device that performs display by rotating in a vertical direction with respect to a liquid crystal display device. On the other hand, as a liquid crystal display device capable of a wide viewing angle, an IPS (In Plane Swi) that performs display by applying an electric field in a direction parallel to the substrate surface and rotating liquid crystal molecules in a plane parallel to the substrate surface.
tching) mode. The IPS mode liquid crystal display device basically looks only in the short axis direction of the liquid crystal molecules even when the viewpoint is moved, has a small viewing angle dependency of the liquid crystal display device, and is wider than the TN mode liquid crystal display device. A viewing angle can be achieved. For this reason, the IPS mode is considered to be used in a field requiring a large viewing angle with a large screen, such as a TV monitor, such as an application viewed from a plurality of persons or from multiple directions.

As such an IPS mode liquid crystal display device, a liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 7-36058 (hereinafter, Conventional Example 2) is known. FIGS. 10A and 10B are views for explaining the liquid crystal display device of Conventional Example 2, in which FIG. 10A is a plan view, FIG. 10B is a cross-sectional view of the TFT portion, and FIG. FIG. As shown in FIG. 10, the liquid crystal display device of Conventional Example 2 has a gate line 1001, a data line 1002, a common line 1003, a common electrode 1005, and a pixel electrode 1004.
And thin film transistor 1006 (Thin Film T)
(hereinafter referred to as TFT). The TFT includes a gate electrode 1007 provided on a TFT-side glass substrate 1011, a gate insulating film 1012 provided so as to cover the gate electrode, a drain electrode 1008 formed on the gate insulating film, and a source. An electrode 1009, an a-Si layer 1010, and a passivation film 1013 provided so as to cover them all are provided. This structure is generally called an inverted staggered structure because it has a structure in which a source electrode and a drain electrode are provided above a gate electrode (a bottom gate structure). The gate line 1001 is for the gate electrode 1007 of the TFT, the data line 1002 is for the drain electrode 1008, and the pixel electrode 1004 is for the source electrode 107.
09, the common line 1003 is electrically connected to the common electrode 1005, respectively. Further, on the passivation film 1013, an alignment film 1014 for controlling the alignment and tilt (pretilt) of the liquid crystal molecules suitable for the liquid crystal operation mode is provided.
A TFT substrate 1019 is formed by components from 011 to an alignment film 1014. Further, the TFT substrate 10
19, a liquid crystal layer 1021 in which liquid crystal molecules are sealed, and a color filter substrate 1020 (hereinafter, referred to as a CF substrate) including a color layer 1016, a black matrix layer 1017, and an alignment film 1015 to form one liquid crystal display device. Has formed.

In Conventional Example 2 having such characteristics, a wider viewing angle can be achieved than in the TN mode, but it is necessary to provide an electrode pair including a pixel electrode 1004 and a common electrode 1005 in a pixel. , The light transmission region 1022 is smaller than that in the TN mode, and the transmittance of the liquid crystal display device is small. Therefore, in order to obtain a bright and excellent display quality liquid crystal display device, it is necessary to increase the backlight luminance,
Power consumption is higher than in the TN mode.

On the other hand, the paper "Electric Field"
d Analysis in TFT-LCDs wi
th In-Plane-Switching Mod
eof Nematic LCs "(Eurodisp
ray '96 Digest 5.1 P.E. 49, hereinafter, the conventional example 3) describes a mechanism of the disturbance of the electric field applied to the liquid crystal due to the leakage electric field of the data line in the IPS mode liquid crystal display device. FIG. 11 is a diagram for explaining the disturbance of the electric field 1115 applied to the liquid crystal due to the leakage electric field 1116 of the data line. For example, a positive signal voltage of 12 V is applied to the data line 1114 and the pixel 1101
Is applied with a negative voltage of 2 V, and the common electrode 11
It is assumed that a reference voltage of 7 V is applied to 02. The leakage electric field 1116 of the data line 1114 penetrates into the display unit as shown in FIG.
To the end. Therefore, in a region where liquid crystal molecules are disturbed, it is necessary to increase the width of the black matrix layer 1109 provided on the CF substrate 1112 to perform light shielding to a required level. Therefore, the light transmission area becomes smaller as compared with the TN mode.

Next, the double speed driving method described in the first conventional example,
An example in which the LCD is configured by simply combining the IPS modes described in Conventional Examples 2 and 3 will be described below. 12A and 12B are diagrams illustrating such a liquid crystal display device, and FIG. 12A is a plan view of pixels in four columns and two rows, and FIG.
(B) is a sectional view thereof. Pixel 1 on data line 1203
222 and 1223 are connected, the pixel 1222 is connected by the gate line 1201, and the pixel 1223 is connected by the gate line 1202.
Is selected. Common electrode 1 adjacent to data line 1203
206 are arranged, and the pixel electrode 1225 of the first pixel and the pixel electrode 1226 of the second pixel are arranged on the side without the data line. Since these driving methods are the same as those in the conventional example 1, the description is omitted.

In this case, since there is no data line between the pixel electrodes 1225 and 1226, it is not necessary to consider the influence of the leakage electric field as in the conventional example 3, and the interval between the pixel electrode 1225 and the adjacent pixel electrode 1226 is reduced. Thus, it is possible to widen the light transmission area. In addition, since the number of data lines is reduced by half, it is considered that power consumption can be reduced and cost can be reduced.

However, even when the double speed driving method is simply applied to an IPS mode liquid crystal display device, the conventional example 1 can be used.
As pointed out as a problem, it is necessary to provide a sufficient space between the pixels 1225 and 1226 so that the first pixel 1225 does not fluctuate due to capacitive coupling when writing the second pixel 1226.

Further, in the present pixel configuration, for example, the pixel 1226 has a positive polarity of 12 V, and the pixel 1225 has a negative polarity of 2 V.
V, the common electrode 1106 is set to a reference potential of 7 V, and FIG.
An unnecessary electric field 1220 that disturbs the electric field 1219 for driving the liquid crystal as shown in FIG. 2 is generated, and disturbs the liquid crystal molecules in the display area as well as the leakage electric field around the data line.
5, 1226, it is necessary to form a large light shielding area by the black matrix 1214 on the CF substrate 1217. As described above, even when the driving method of the conventional example 1 is applied to the IPS liquid crystal display device, there is a problem that the display quality is deteriorated unless the pixel configuration and the polarity of the write signal to the pixel are sufficiently considered.

[0016]

As described above, in the double-speed driving method of the first conventional example, the distance between adjacent pixels is sufficiently widened, the parasitic capacitance between pixels is reduced, and deterioration of display quality is reduced. Therefore, there is a problem that the light transmission area is reduced. Also, when this double speed driving method is applied to an IPS liquid crystal using an electric field parallel to the substrate surface,
Unless the pixel configuration and the polarity of the write signal to the pixel are sufficiently taken into consideration, there is a problem that the display quality deteriorates and the light transmission area decreases.

Therefore, an object of the present invention is to apply the double speed driving method as in the prior art 1 to the IPS mode to obtain a wide viewing angle and a wide viewing angle.
It is an object of the present invention to provide a bright liquid crystal display device with low power consumption, low cost, a wide light transmission area, and excellent display quality.

[0018]

According to the present invention, a first active matrix type liquid crystal display comprises an active element substrate, a counter substrate, and a liquid crystal layer sandwiched between the two substrates. It has pixels arranged in a matrix consisting of pixel electrodes and a common electrode on the substrate surface, and a thin film transistor having a gate, a drain and a source electrode. In an active matrix type liquid crystal display device that performs display by rotating in a plane parallel to an element substrate, the active element substrate is provided with two gate lines assigned to one row of the pixels arranged in a matrix. A data line assigned to each of the two columns of the pixels, and a common line for supplying a reference potential to a common electrode, wherein one of the two gate lines is provided. And a second group of pixels driven via a thin film transistor (TFT) selected by another gate line and a thin film transistor (TFT) selected by the other gate line. As a result, an active matrix liquid crystal display device is obtained.

Further, according to the present invention, as a second active matrix type liquid crystal display device, in the first liquid crystal display device, two pixels are provided between the first group of pixels and the second group of pixels. An active matrix type liquid crystal display device having a common electrode shared by the above is obtained.

Further, according to the present invention, as a third active matrix type liquid crystal display device, in the second liquid crystal display device, the common electrode shared between the first group of pixels and the second group of pixels is provided. According to the present invention, an active matrix type liquid crystal display device, which also serves as the common line, can be obtained.

Further, according to the present invention, as a fourth active matrix type liquid crystal display device, in the first liquid crystal display device, between the first group of pixels and the second group of pixels, one is provided. An active matrix liquid crystal display device characterized in that the common line is arranged on the other side of the data line is obtained.

Further, according to the present invention, as a fifth active matrix type liquid crystal display device, in the fourth liquid crystal display device, the pixel electrode and the common electrode are connected to a long side parallel to a scanning line and a data line. An active matrix liquid crystal display device characterized by being formed by a rectangular pattern having parallel short sides is obtained.

Further, according to the present invention, as the sixth active matrix type liquid crystal display device, the second or fourth active matrix type liquid crystal display device can be used.
In the liquid crystal display device of the above, in the surface of the counter substrate,
An active matrix liquid crystal display device is characterized in that no light-shielding pattern exists in a region facing a common electrode or a common line shared by the first group of pixels and the second group of pixels.

Further, according to the present invention, as a seventh active matrix type liquid crystal display device, in the first liquid crystal display device, the pixel driving method may be such that the scanning period of each scanning line is set to the first scanning period and the first scanning period. Divided into the second scanning period,
In the scanning period, the first pixel is driven, and in the second scanning period, the second pixel is driven. The first group of pixels is different from the first pixel arranged next to the first group. The second group of pixels connected to the data lines have the same polarity as each other, thereby obtaining an active matrix liquid crystal display device.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be sequentially described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a view for explaining an active matrix liquid crystal display device according to a first embodiment of the present invention, and FIG. 1 (a) is a plan view showing a pixel array arrangement of four columns and two rows. And (b) is an enlarged view of the pixel portion. In the active matrix type liquid crystal display device according to the first embodiment of the present invention, an active element substrate (hereinafter, referred to as a TFT substrate)
And a counter substrate (hereinafter referred to as a CF substrate) and a liquid crystal layer interposed therebetween. Pixel electrodes are arranged on a 640 × 3 × 480 matrix on the TFT substrate,
Two gate lines 101 are assigned to one display line in the scanning direction, two by two, and have 320 × 3 data lines 103 and 480 common lines 105 arranged in parallel with the gate lines 101. Pixels 111 which are selected by the gate line 101 and write the signal of the data line 103 and pixels 112 which are selected by the other gate line 102 and write the signal of the data line 103 are arranged on the left and right sides of the data line 103. Each of the pixels 111 and 112 has one pixel electrode 118 and two common electrodes 116 and 117. One common electrode 116 is arranged adjacent to the data line 103, and the other common electrode 117 is a data electrode adjacent to the pixel 111. The pixel 111 and the pixel 113 are arranged between the pixels 113 connected to the line 104 and share a common electrode 117. The pixel electrode 118 is arranged at the center of the common electrodes 116 and 117. The pixel electrode 118 is a TFT 106
Of the common electrodes 116 and 11
Reference numeral 7 is connected to a common line 105 arranged in parallel with the gate line 101. In a pixel selected by the selection signal supplied to the gate line 101 and the data signal supplied to the data line 103, the pixel 7 is connected to the substrate surface. An electric field is generated in a substantially horizontal plane, and the liquid crystal molecules 11 are generated according to the electric field 115.
4 is rotated in a plane parallel to the substrate surface to perform display.

Next, the layer structure of the pixel according to the first embodiment of the present invention will be described with reference to FIG. 2A and 2B are diagrams showing a layer structure of the first embodiment, wherein FIG. 2A is a cross-sectional view of a TFT portion, and FIG. 2B is a cross-sectional view around a data line. The layer structure of the pixel of the present invention is formed by using a common electrode 116, a common line 105, and a gate line 102 by using a gate layer of an inverted staggered TFT having a bottom gate structure provided on a TFT glass substrate 121.
Is formed, and the data line 104 is formed by using the drain layer.
And pixel electrodes 118 and 119 are formed, and a passivation film 123 is formed so as to cover the TFTs and protect the TFTs. Further passivation film 1
An alignment film 124 for aligning liquid crystal molecules is provided on the TFT 23, and the alignment film 124 is
The TFT substrate 129 is formed by the above components. On the other hand, the color filter substrate 130 includes a CF-side glass substrate 128, a black matrix layer 127 (hereinafter, referred to as a BM layer) for shielding non-display portions, a color layer 126 which is a resin containing a pigment or a dye having three primary colors of RGB, and a liquid crystal. Is composed of an alignment film 125 for orienting the substrate.

Although the BM layer 127 is provided in a non-display area around the gate line 102 and the data line 104, the BM layer is provided on the common electrode 117 shared by the first pixel and the second pixel. Not.

The driving method according to the first embodiment is performed as shown in FIG. 3A is a diagram showing the driving order of the pixels, and FIG. 3B is a diagram showing a signal of each line or pixel.

The scanning period 142 of each scanning line is divided into a first scanning period 143 and a second scanning period 144, and one pixel 111 arranged on one side of the data line 103 is driven in the first scanning period 143. In the second scanning period 144, the other pixel 112 is driven. The writing to the pixel is performed, for example, as follows. For the pixels connected to the data line 103, the pixels 111 → 112 → 132 →
Writing is performed in the order of 133, and for the pixels connected to the data line 104, the pixels 134 → 113 → 135 → 1
Writing is performed in the order of 36.

The polarities of the signals for these pixels are as follows:
For example, there are a dot inversion method in which the polarity is inverted for each pixel, and a 2H1V dot inversion method in which dot inversion is performed by setting the polarity of two pixels sharing a common electrode as a pair.

FIGS. 4A and 4B are diagrams for explaining the case where the dot inversion method is applied. FIG. 4A shows a writing method for each pixel, FIG. 4B is a plan view of a pixel array, and FIG. FIG. In the dot method, driving is performed with the polarity inverted for each pixel. As shown in FIGS. 4B and 4C, the pixel electrode 119 of one of the pixels 113 has a positive polarity 1
2V is applied to the pixel electrode 11 of the other pixel 111
8 has a negative polarity of 2V. Common electrode 11
6, 117 is applied with a reference potential of 7V. In the case of such dot inversion driving, in addition to the parallel electric field 115 applied to the liquid crystal molecules 114 formed by the pixel electrodes 118 and 119 and the common electrodes 116 and 117, a leakage electric field 145 is generated between the pixel electrodes 118 and 119. In addition, since the liquid crystal molecules in the display unit are disturbed, display quality is deteriorated. Therefore, when the driving method of the first conventional example is applied to the IPS mode, the conventional dot inversion driving cannot be applied.

FIG. 5 is a diagram for explaining a case where a 2H1V dot inversion method in which dot inversion is performed with a pair of polarities of two pixels sharing a common electrode is applied. FIG. 5A shows a writing method for each pixel. (b) is a plan view of the pixel array, and (c) is a cross-sectional view thereof. In the 2H1V dot inversion method, as shown in FIG. 5A, pixels 111 and 113 sharing a common electrode are regarded as a pixel pair, and driving is performed with the polarity inverted for each pixel pair. As shown in FIGS. 5B and 5C, the pixel electrode 119 of one of the pixels 113 has one positive polarity.
2V is applied to the pixel electrode 11 of the other pixel 111
8 also has a positive 12V. Common electrode 1
A reference potential of 7 V is applied to 16, 117. In the case of the 2H1V dot inversion driving, no leakage electric field is generated between the pixel electrode 119 and the pixel electrode 118 as described above, so that the liquid crystal molecules are not disturbed, so that the display quality does not deteriorate. Therefore, in the present embodiment, a 2H1V dot inversion method of performing dot inversion using a pair of polarities of two pixels sharing a common electrode is applied as a polarity of a signal written to a pixel.

The features of the first embodiment described above are as follows.

A double-speed driving method capable of halving the number of data is IP
By applying to the S mode, power consumption can be reduced and cost can be reduced.

Further, between the pixel 111 and the pixel 113,
The common electrode 1 shared by these pixels, not the pixel electrode
By arranging the pixels 17, the distance between the pixel electrodes of the pixels 111 and 113 can be made sufficient, the parasitic capacitance between the pixels can be reduced, and the deterioration of display quality, which is a problem in the double-speed driving method, can be prevented.

Since there is no need to dispose a BM layer on these shared common electrodes 117 provided between the pixels 111 and 113, the area of the display region through which light is transmitted is greatly increased as compared with the related art. I do. Thus, a liquid crystal display device having high light transmittance and excellent display quality can be provided.

Further, as a method of writing to the pixel,
By applying the 2H1V dot inversion method of performing dot inversion with a pair of polarities of two pixels sharing a common electrode, it is possible to provide a liquid crystal display device having excellent display quality without causing a leakage electric field between pixel electrodes. (Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. 6A and 6B are diagrams showing a second embodiment, in which FIG. 6A is a plan view of a pixel, and FIG. 6B is a cross-sectional view thereof.

As shown in FIG. 6A, pixel electrodes are arranged on a TFT substrate in a 640 × 3 × 480 matrix, and 960 gate lines 601 are provided for two display lines in the scanning direction. Allocated one by one, 320 × 3 data lines 602, and 3 arranged in parallel with the data lines 602
It has 20 common lines 603. Data lines 602 are selected on the left and right of the data line 602 by the gate line 601.
606 and the other gate line 62 to which the signal of
A pixel 607 which is selected by 0 and writes a signal of the data line 602 is arranged. Pixels 606 and 607 each have one pixel electrode 604 and one common electrode 605
And a common line 603 also serving as a common electrode is shared.

Next, a layer structure of a pixel according to a second embodiment of the present invention will be described with reference to FIG. The gate line 6 is formed by using an inverted staggered TFT gate layer having a bottom gate structure.
01 is formed, and the data line 6 is formed by using the drain layer.
02, a pixel electrode 604, a common line 603 and common electrodes 605 and 603 are formed, and a passivation film 610 is formed so as to cover them.

The order and polarity of writing signals to the pixel array are the same as in the first embodiment, and a description thereof will be omitted.

The feature of this embodiment is that the common electrode provided between the pixel 606 and the pixel 607 also serves as the common line 603 as compared with the first embodiment. The point is that the area through which light is transmitted is further improved.

Further, since the common electrode and the pixel electrode are in the same layer, the symmetry of the electric field applied to the liquid crystal layer by the two electrodes is improved, and for example, a liquid crystal display excellent in display quality with little occurrence of burn-in, unevenness and stains, etc. A device is obtained. (Third Embodiment) Next, a third embodiment of the present invention will be described. Note that the pixel array arrangement of the present embodiment is the same as that of the second embodiment, and a description thereof will be omitted. 7A and 7B are diagrams showing a third embodiment, in which FIG. 7A is a plan view of a pixel, and FIG. 7B is a sectional view thereof. As in the second embodiment, a common line 703 is arranged between the pixels 706 and 707. The common electrode 705 connected to the pixel electrode 704 and the common line 703 has its long side arranged in parallel with the gate line 701.

The layer structure and the order / polarity of writing signals to the pixel array are the same as in the second embodiment, and a description thereof will be omitted.

The feature of this embodiment is that the data line 70
2 and the common line 703 and the common electrode 705 are arranged in the same layer, but the area of the adjacent portion is smaller than that in the second embodiment. Therefore, a new metal layer is provided to increase the number of processes. Therefore, it is possible to reduce a defective rate of a short circuit between the data line and the common electrode / common electrode line.

[0045]

As described above, the first advantage of the present invention is that a wide viewing angle can be realized by rotating the liquid crystal molecules in the plane parallel to the active element substrate to perform display. In the IPS type wide viewing angle liquid crystal display device described above, a low-cost liquid crystal display device with low power consumption can be provided.

The reason is that two scanning lines are assigned to one row of pixels, two data lines are assigned to two columns of pixels, and a common line is connected to a common electrode. A first pixel driven through a thin film transistor (TFT) having a gate electrode connected to one of the scan lines, a drain electrode connected to the data line, and a gate electrode connected to the other scan line. A pixel array arrangement having a second pixel driven via a thin film transistor (TFT) with a drain electrode connected to a line is performed, and furthermore, the first pixel and the second pixel share a part of a common electrode. It is. Further, when the common electrode also serves as the common line, the aperture ratio can be further increased.

A second effect of the present invention is that an IPS type liquid crystal display device to which double-speed driving is applied can provide a liquid crystal display device having excellent display quality.

The reason for this is that the 2H1V dot inversion method of performing dot inversion with the polarity of two pixels sharing a common electrode as a pair reduces the leakage electric field generated between pixels.

The third effect of the present invention is that an IPS type wide viewing angle liquid crystal display device capable of driving at double speed is provided.
Shortening of data line and common line while maintaining high aperture ratio,
It is to improve the yield.

This is because when the data line and the common line are in the same layer,
This is obtained by arranging the long side direction of the common electrode in parallel with the gate line to reduce the area of the portion adjacent to the common electrode and the data line.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a part of an active matrix type liquid crystal display device of the present invention, wherein FIG. 1A is a plan view of a pixel array of four columns and two rows, and FIG. .

FIGS. 2A and 2B are diagrams showing a part of an active matrix type liquid crystal display device of the present invention, wherein FIG. 2A is a cross-sectional view of the TFT portion (AA ′ cross-sectional view of FIG. 1B); FIG. 1B is a cross-sectional view around the data line (a cross-sectional view taken along line BB ′ in FIG. 1B).

3A and 3B are diagrams showing a driving method of the active matrix type liquid crystal display device of the present invention, wherein FIG. 3A is a diagram showing a writing order, and FIG. 3B is a diagram showing each signal.

4A and 4B are diagrams showing a part of an active matrix type liquid crystal display device of the present invention, wherein FIG. 4A is a diagram showing the polarity of a pixel signal, FIG. 4B is a plan view of a pixel, and FIG. Is a sectional view around the data line.

FIG. 5A is a diagram showing the polarity of a pixel signal;
(B) is a plan view of the pixel, and (c) is a cross-sectional view around the data line.

FIG. 6 is a diagram showing a part of an active matrix type liquid crystal display device of the present invention, wherein (a) is a plan view of a pixel,
(B) is a sectional view around the data line.

FIG. 7 is a diagram showing a part of an active matrix type liquid crystal display device of the present invention, wherein (a) is a plan view of a pixel,
(B) is a sectional view around the data line.

FIG. 8 is a diagram showing a part of a conventional active matrix liquid crystal display device.

9A and 9B are diagrams illustrating a driving method of a conventional active matrix type liquid crystal display device, in which FIG. 9A illustrates a writing order, and FIG. 9B illustrates signals.

10A and 10B are diagrams illustrating a part of a conventional active matrix type liquid crystal display device, in which FIG. 10A is a plan view of the pixel, FIG. 10B is a cross-sectional view of the TFT part, and FIG. It is sectional drawing around the data line.

FIG. 11 is a cross-sectional view around a data line of a pixel portion of a conventional active matrix liquid crystal display device.

12A and 12B are diagrams illustrating a part of a conventional active matrix liquid crystal display device, in which FIG. 12A is a plan view of a pixel array of 4 columns and 2 rows, and FIG. 12B is a cross-sectional view around a data line thereof. is there.

[Explanation of symbols]

 101, 102 Gate line 103, 104 Data line 105 Common electrode line 106 Thin film transistor 107 Gate electrode 108 Drain electrode 109 Source electrode 110 Light transmission region 111, 112, 113 Pixel 114 Liquid crystal molecule 115 Electric field direction 116 Common electrode 117 Pixel 111 and pixel Common electrode shared by 113 118 Pixel electrode of pixel 111 119 Pixel electrode of pixel 113 120 a-Si layer 121 TFT glass substrate 122 Gate insulating film 123 Passivation film 124 Alignment film (TFT side) 125 Alignment film (CF side) 126 Color Layer 127 Black matrix layer 128 CF glass substrate 129 TFT substrate 130 CF substrate 131 Liquid crystal layer 132-136 Pixel 137 Signal of gate line 101 138 Signal of gate line 102 139 Data line 1 03 signal 140 voltage of pixel 111 141 voltage of pixel 112 142 scanning period 143 first scanning period 144 second scanning period 145 leakage electric field 601 gate line 602 data line 603 common electrode line 604 pixel electrode 605 common electrode 606 607 Pixel 608 TFT glass substrate 609 Gate insulating film 610 Passivation film 611 Alignment film (TFT side) 612 Alignment film (CF side) 613 Color layer 614 Black matrix layer 615 CF glass substrate 616 TFT substrate 617 CF substrate 618 Liquid crystal layer 619 Pixel 606 Common electrode 620 common line shared by pixel 607 and light transmitting region 701 gate line 702 data line 703 common electrode line 704 pixel electrode 705 common electrode 706 and 707 pixel 708 TFT glass substrate 709 gate insulating film 710 Passivation film 711 alignment film (TFT side) 712 alignment film (CF side) 713 color layer 714 black matrix layer 715 CF glass substrate 716 TFT substrate 717 CF substrate 718 liquid crystal layer 719 common electrode shared by pixel 706 and pixel 707 720 light Transmission area 801 Gate line 802 Data line 803 Pixel electrode 804 Thin film transistor 805 Scan driver 806 Signal driver 807 Display unit 901, 902 Gate line 903, 904 Data line 905-912 Pixel C1 Pixel capacitance between pixel 905 and pixel 906 C2 Pixel 905 Pixel capacitance between pixel and pixel 910 915 scanning period 916 first scanning period 917 second scanning period 918 pixel voltage shift 919 signal on gate line 901 920 signal on gate line 902 921 data line 903 Signal 922 Pixel 905 voltage 923 Pixel 906 voltage 1001 Gate line 1002 Data line 1003 Common electrode line 1004 Pixel electrode 1005 Common electrode 1006 Thin film transistor 1007 Gate electrode 1008 Drain electrode 1009 Source electrode 1010 a-Si layer 1011 TFT glass substrate 1012 Gate insulation Film 1013 Passivation film 1014 Alignment film (TFT side) 1015 Alignment film (CF side) 1016 Color layer 1017 Black matrix layer 1018 CF glass substrate 1019 TFT substrate 1020 CF substrate 1021 Liquid crystal layer 1022 Light transmission region 1101 Pixel electrode 1102 Common electrode 1103 TFT Glass substrate 1104 Gate insulating film 1105 Passivation film 1106 Alignment film (TFT side) 1107 Alignment film (CF 1108 Color layer 1109 Black matrix layer 1110 CF glass substrate 1111 TFT substrate 1112 CF substrate 1113 Liquid crystal layer 1114 Data line 1115 Electric field applied to liquid crystal 1116 Leakage electric field from data line 1201, 1202 Gate line 1203, 1204 Data line 1205 Common electrode line 1206 common electrode 1207 thin film transistor 1208 TFT glass substrate 1209 gate insulating film 1210 passivation film 1211 alignment film (TFT side) 1212 alignment film (CF side) 1213 color layer 1214 black matrix layer 1215 CF glass substrate 1216 TFT substrate 1217 CF substrate 1218 liquid crystal Layer 1219 Electric field applied to liquid crystal 1220 Leakage electric field 1221 Light transmission area 1222 to 1224 Pixel 1225 Pixel 1222 Pixel electrodes of the pixel electrode 1226 pixels 1224

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1362 G02F 1/1343 G02F 1/133 G09F 9/30 G09G 3/36

Claims (7)

(57) [Claims] 1. A pixel comprising: an active element substrate; a counter substrate; and a liquid crystal layer sandwiched between the two substrates. The pixel includes a pixel electrode and a common electrode arranged in a matrix on the surface of the active element substrate. And a thin film transistor having a gate, a drain, and a source electrode, wherein an active matrix type liquid crystal display device performs display by rotating a molecular axis direction of liquid crystal molecules of the liquid crystal layer in a plane horizontal to the active element substrate. The active element substrate includes two gate lines assigned to one row of the pixels arranged in a matrix, and two data lines assigned to two columns of the pixels. A thin film transistor having a common line for supplying a reference potential to a common electrode and selected by one of the two gate lines assigned to each row of the pixel, two by two An active matrix type liquid crystal display device comprising a first group of pixels driven through a thin film transistor and a second group of pixels driven through a thin film transistor selected by another gate line. 2. An adjacent 2 connected to different data lines.
2. The active matrix liquid crystal display device according to claim 1, wherein a common electrode shared by both pixels is provided between pixels. 3. A common electrode shared by two adjacent pixels connected to the different data lines communicates in a direction parallel to the data lines and also serves as a part of a common line for supplying a reference potential to the common electrodes. The active matrix type liquid crystal display device according to claim 2, wherein: 4. An adjacent 2 connected to different data lines.
2. The active matrix type liquid crystal display device according to claim 1, wherein a common line for supplying a reference potential to a common electrode of both pixels is provided between the pixels. 5. The active matrix liquid crystal display device according to claim 4, wherein the pixel electrode and the common electrode forming the pixel are formed in a direction parallel to a gate line. 6. The light-shielding pattern is not formed in a region facing a common electrode or a common line shared by two adjacent pixels connected to the different data lines in the surface of the counter substrate. 5. The active matrix liquid crystal display device according to 2 or 4. 7. The active matrix liquid crystal display device according to claim 1, wherein two adjacent pixels connected to the different data lines have the same polarity.