JP2001133808A - Liquid crystal display device and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device and a driving method therefor by which favorable display quality can be obtained with low power consumption, relating to the liquid crystal display device of what is called a lateral electric field system and the driving method therefor. SOLUTION: This liquid crystal display device is configured so as to comprise a TET 1 formed in each pixel area on an array substrate, a display electrode 2 connected with the TFT 1 on the array substrate, a common electrode 4 formed to face the display electrode 2 in each pixel area on the array substrate, and a TFT 3 connected with the common electrode 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor (TFT).
Matrix type liquid crystal display device using a switching element as a switching element and a driving method thereof,
The display electrode and the common electrode are both provided on the array substrate on which the T is formed, and a voltage is applied between both electrodes to control the alignment of the liquid crystal mainly by an electric field of a component parallel to the array substrate surface. The present invention relates to a so-called horizontal electric field type liquid crystal display device for displaying an image and a driving method thereof.

[0002]

2. Description of the Related Art Conventionally, an array substrate on which TFTs and display electrodes are formed, and an opposing substrate on which a common electrode is formed opposing the array substrate, have a TN (twist) between the array substrate and the opposing substrate. A nematic (TN) liquid crystal display device in which a liquid crystal layer is sealed has been mainly used. This liquid crystal display device applies a voltage between a display electrode and a common electrode, controls the orientation of liquid crystal by an electric field having a component perpendicular to the array substrate, and displays an image by controlling the orientation of the liquid crystal. Is used.

In recent years, both a display electrode and a common electrode have been provided on an array substrate on which TFTs have been formed. When a voltage is applied between the two electrodes, a liquid crystal is mainly generated by an electric field of a component parallel to the array substrate surface. A so-called horizontal electric field type liquid crystal display device that displays an image by controlling the orientation has appeared. As an example of the in-plane switching type liquid crystal display device, an in-plane switching (IPS) type liquid crystal display device can be given. The liquid crystal display device based on the IPS system is being commercialized as a monitor display device or the like. A horizontal electric field type liquid crystal display device can provide a display with a wider viewing angle than a vertical electric field type TN type liquid crystal display device, and it is not necessary to form a display electrode or a common electrode with a transparent electrode material. There is an advantage that the manufacturing process of the TFT can be simplified and the manufacturing cost can be reduced.

A configuration for one pixel of a conventional in-plane switching type liquid crystal display device will be described with reference to an equivalent circuit shown in FIG. As shown in FIG. 15, a plurality of data bus lines 108 (only one is shown in FIG. 15) extending vertically in the figure are formed on the array substrate. Further, on the array substrate, a plurality of scan bus lines 106 (only one is shown in FIG. 15) extending perpendicularly to the data bus lines 108 and extending in the horizontal direction in the figure are formed. An area defined by the data bus line 108 and the scan bus line 106 is a pixel area. The TFT 100 is formed near the intersection of each data bus line 108 and scan bus line 106. The drain electrode D of the TFT 100 is connected to the data bus line 108. The source electrode S and the display electrode 102 are simultaneously formed of the same metal. The gate electrode G is connected to the scan bus line 106.

Although not shown, the display electrode 102 also serving as the source electrode S has a structure formed in a comb shape.
Then, on the array substrate, a common electrode 104 shaped like a comb tooth is formed so as to face the comb tooth of the display electrode 102 so as to mesh therewith. Common electrode is common bus line 110
It is connected to the.

A driver circuit for supplying a signal to each bus line is formed by sealing a liquid crystal layer on the array substrate on which the above-described pixels are formed, and bonding the opposing substrate (not shown) on which a color filter and the like are formed. (Not shown) is mounted to constitute a main part of the liquid crystal display device.

From the data driver circuit, a gradation signal (data voltage) Vd corresponding to a pixel to be driven is supplied to each data bus line 108. Further, a scanning signal Vg for turning on a predetermined TFT 100 is supplied to a predetermined scan bus line 106 from the gate driver circuit. The common bus line 110 has a common potential Vc.
om is supplied. Display electrode 102 and common electrode 104
A liquid crystal capacitance Clc is formed by the liquid crystal in between.

In this conventional liquid crystal display device of the lateral electric field type, the common electrode 10 of each pixel directly connected to the common bus line 110 maintained at a constant common potential Vcom.
With respect to 4, an image is displayed by writing the data voltage Vd to the display electrode 102 via the TFT 100 and controlling the electric field in the liquid crystal layer.

[0009]

However, the liquid crystal display device of the horizontal electric field type has a higher driving voltage than the liquid crystal display device of the vertical electric field type, and accordingly, the amplitude of the data voltage Vd is increased and the power consumption is increased. Has the problem of becoming large. Further, there is a problem that the increase in the amplitude of the data voltage Vd causes a decrease in display quality because of an increase in crosstalk.

An object of the present invention is to provide a liquid crystal display device which displays an image by controlling the orientation of liquid crystal by applying a voltage between a display electrode and a common electrode formed on an array substrate, and a method of driving the same. An object of the present invention is to provide a liquid crystal display device capable of obtaining good display quality with electric power and a driving method thereof.

[0011]

The object of the present invention is to provide a first switching element formed in each pixel region on an array substrate, a display electrode connected to the first switching element on the array substrate, This is achieved by a liquid crystal display device comprising: a common electrode formed facing the display electrode for each of the pixel regions on the array substrate; and a second switching element connected to the common electrode. .

In the above liquid crystal display device of the present invention, the liquid crystal display device has a plurality of common bus lines for supplying a common potential to the common electrode in the pixel region via the second switching element. , A plurality of common bus groups for connecting the common buses are formed.

Further, in the liquid crystal display device according to the present invention, the plurality of common bus lines are formed in parallel with either the scan bus line or the data bus line, and the common bus lines are connected to every other line. The first common bus group and the second common bus group.

In the liquid crystal display device according to the present invention, the liquid crystal display device has a plurality of common bus lines for supplying a common potential to the common electrode in the pixel region via the second switching element. One common bus line is assigned to two of the pixel regions adjacent to each other along one of the bus lines.

The above object is also achieved by providing a switching element formed in each pixel region on an array substrate, a display electrode connected to the switching element on the array substrate, and a display electrode facing the display electrode on the array substrate. A common electrode formed by applying a voltage between the display electrode and the common electrode to control an orientation of liquid crystal by an electric field of a component parallel to the array substrate surface to display an image. In the method for driving a liquid crystal display device, the common potential applied to the common electrode takes two different potentials corresponding to the positive and negative polarities of the voltage applied to the liquid crystal. This is achieved by a driving method.

According to the present invention, for example, a thin film transistor is used as the second switching element connected to the common electrode of each pixel, and the voltage applied to the liquid crystal is changed at the timing when data is written to the corresponding display electrode via the thin film transistor. Since a common potential composed of two different potentials corresponding to positive and negative is written to each common electrode, the amplitude of the data voltage can be reduced. By reducing the data voltage amplitude, it is possible to reduce the power consumption of the liquid crystal display device, and it is possible to reduce crosstalk and obtain excellent display quality.

Further, since the channel area of the thin film transistor connected to the display electrode of each pixel is made substantially the same as the channel area of the thin film transistor connected to the common electrode, the thin film transistor connected to the display electrode is used. The DC level shift of the display electrode (the phenomenon that the potential written to the display electrode when the thin film transistor is turned on and the potential changes when the thin film transistor is turned off due to the gate capacitance coupling of the thin film transistor) and the DC of the common electrode by the thin film transistor connected to the common electrode The level shift can be made about the same size. Therefore, the voltage applied to the liquid crystal during data writing (when the thin film transistor is on) and during the holding period (when the thin film transistor is off) can be made substantially the same. Furthermore, since the voltage applied to the liquid crystal can be made substantially the same between the positive and negative frames, it is easy to remove the DC component and drive the liquid crystal by alternating current, and to prevent burn-in and the like to prevent display quality. And reliability can be further improved. Further, since the storage capacitance can be reduced, the area of the storage capacitance wiring in the display region can be reduced, and the aperture ratio of the pixel can be improved.

When a common bus line for supplying a common potential to the common electrode via a thin film transistor is formed in parallel with the scan bus line, every other common bus line is connected to the first common bus group and the first common bus group. By combining them into two common bus groups, 1H inversion driving can be easily realized, and the display quality can be improved.

Further, by connecting the drain electrode (or source electrode) of the thin film transistor connected to the common electrode of two adjacent pixels to one common bus line, the number of common bus lines in the display area can be reduced. Since it can be reduced by half, the aperture ratio of the pixel can be improved.

Furthermore, if at least a peripheral circuit for driving the common bus line is integrated with a thin film transistor provided for each pixel and formed on an insulating substrate, the manufacturing cost can be further reduced. In addition, by using polycrystalline silicon as a main component for the operation semiconductor layer of the thin film transistor connected to the common electrode, a liquid crystal display device with an integrated peripheral circuit can be easily realized.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display according to an embodiment of the present invention and a driving method thereof will be described with reference to FIGS. The liquid crystal display device according to the present embodiment uses a so-called horizontal electric field type liquid crystal driving method. First,
A schematic configuration of the liquid crystal display device according to the present embodiment will be described using an equivalent circuit shown in FIG.

As shown in FIG. 1, a plurality of data bus lines 8 (only one is shown in FIG. 1) extending vertically in the figure are formed on the array substrate. On the array substrate, a plurality of scan bus lines 6 (only one is shown in FIG. 1) extending orthogonally to the data bus lines 8 and extending in the left-right direction in the figure. The area defined by the data bus line 8 and the scan bus line 6 is a pixel area. The TFT 1 is formed near the intersection of each data bus line 8 and scan bus line 6. The drain electrode D of the TFT 1 is connected to the data bus line 8. The display electrodes 2 connected to the source electrodes S are simultaneously formed of the same metal. The gate electrode G is connected to the scan bus line 6.

Although not shown, the display electrode 2 also serving as the source electrode S has a structure formed in a comb shape. Then, a common electrode 4 formed in a comb-like shape is formed facing the comb-like teeth of the display electrode 2 on the array substrate so as to mesh therewith.

In the present embodiment, the common electrode 4 is connected to the source electrode S of the TFT 3 formed separately from the TFT 1 in the pixel area. Gate electrode G of TFT3
Are connected to the same scan bus line 6 as the gate electrode G of the TFT 1. The drain electrode D of the TFT 3 is connected to the common bus line 10. TFT3 is TF
It is formed simultaneously in the same step as T1. Also, TF
The source electrode S of T3 and the common electrode 4 are simultaneously formed of the same material.

A driver circuit for supplying a signal to each bus line is formed by sealing a liquid crystal layer on the array substrate on which the above-described pixels are formed and bonding it to a counter substrate (not shown) on which color filters and the like are formed. (Not shown) is mounted to constitute a main part of the liquid crystal display device.

From the data driver circuit, a gradation signal (data voltage) Vd corresponding to the pixel to be driven is supplied to each data bus line 8. Further, a scanning signal Vg for turning on predetermined TFTs 1 and 3 is supplied to a predetermined scan bus line 6 from the gate driver circuit. The common bus line 10 has a common potential Vco
m is supplied. The liquid crystal between the display electrode 2 and the common electrode 4 forms a liquid crystal capacitance Clc.

As described above, in the liquid crystal display device according to the present embodiment, the TFT 1 as the first switching element formed in each pixel region on the array substrate and the display connected to the TFT 1 on the array substrate An electrode 2 and a common electrode 4 formed on the array substrate so as to face the display electrode 2
And a TFT 3 as a second switching element connected to the common electrode 4.

Next, a method of driving the liquid crystal display device according to the present embodiment will be described with reference to FIGS. FIG.
Shows a drive waveform for driving the liquid crystal display device according to the present embodiment. As is clear from FIGS. 1 and 2, when the scanning signal Vg on the scan bus line 6 becomes “H” level, the TFT 1 is turned on and the TFT 3 is turned on at the same time. When the TFT 1 is turned on, the data voltage Vd on the data bus line 8 is written to the display electrode 2 and
When T3 is turned on, the common potential Vcom on the common bus line 10 is written to the common electrode 4.

In this embodiment, in order to prevent the deterioration of the liquid crystal, AC driving is performed in which the voltage applied to the liquid crystal is inverted every frame. Therefore, when a certain gradation is continuously displayed, the data voltage Vd is output such that the absolute value of the voltage does not change but the positive and negative polarities are inverted every frame.

On the other hand, the common potential Vcom applied to the common electrode 4 is driven so as to be inverted every frame with a polarity opposite to the polarity of the data voltage Vd. For example, the common electrode 4 has two common potentials Vcom = Vc of different polarities.
h or Vcl (Vch> Vcl) is alternately applied for each frame.

For example, taking a normally black liquid crystal display device as an example, when the liquid crystal performs the darkest display (black), the magnitude of the voltage applied to the liquid crystal is Vb, and the brightest display (white) is performed. The magnitude of the voltage applied to the liquid crystal is set to Vw (Vw> Vb). In the n-th frame, if a positive data voltage Vd is applied to the display electrode 2 and a negative common potential Vcom = Vcl is applied to the common electrode 4, the data voltage Vd = Vb to display black.
+ Vcl. To display white, the data voltage Vd = V
w + Vcl. Therefore, the range (Vd range) of the data voltage Vd in the n-th frame is Vw-Vb.

In the (n + 1) th frame, black is displayed if the negative data voltage Vd is applied to the display electrode 2 and the positive common potential Vcom = Vch is applied to the common electrode 4. Has a data voltage Vd = −V
b + Vch, and to display white, the data voltage Vd =
−Vw + Vch. Therefore, the range (Vd range) of the data voltage Vd in the (n + 1) th frame is also Vw-Vb as in the case of the nth frame. Therefore, in the liquid crystal display device according to the present embodiment, the range (Vd range) that data voltage Vd can take over all frames is Vw.
−Vb.

Here, as a comparative example, the common potential Vcom
With reference to FIG. 3, a description will be given of a conventional driving method for performing one-frame inversion driving while keeping the constant. In the case of a normally black liquid crystal display device similar to that described above, in the conventional one-frame inversion driving method, the common potential Vcom is constant, so that the brightest display (white) is performed. Only the magnitude Vw needs to be considered, and the range (Vd range) that the data voltage Vd can take is 2 × Vw over the entire frame.

For example, if Vw = 6V and Vb = 2V, in the liquid crystal display device according to the present embodiment, (Vd range) = Vw−Vb = 4V, and the conventional (Vd range) =
With respect to 2 × Vw = 12 V, the voltage range can be reduced to １ ／. As a result, the crosstalk based on the fluctuation of the signal on the data bus line 8 can be reduced to 1/3, so that the display quality can be greatly improved. The power consumption related to the data bus line is 1 /
9 can be reduced.

Although not specifically shown, in the present embodiment, the TF connected to the display electrode 2 in each pixel region is used.
The channel area of T1 and the T connected to the common electrode 4
The FT3 is formed so that the channel area is substantially the same. The effect of this will be described with reference to FIGS. 4 and 5 show changes in the potentials of the common electrode 4 and the display electrode 2 for each frame, FIG. 4 shows the results obtained by using the configuration and the driving method of the present embodiment, and FIG. 5 shows a comparative example. Shows the result of using the conventional configuration and driving method.

First, in the conventional liquid crystal display device shown in FIG. 15, when a predetermined scan bus line 106 is selected, as shown in FIG. 5, the TFT 1 connected to the scan bus line 106 is turned on, and The data voltage Vd + is written to the display electrode 2 in a frame (a frame to which a positive voltage is applied; the same applies hereinafter), and Vd- is written to a negative frame (a frame to which a negative voltage is applied; the same applies hereinafter). The scan bus line 6 is deselected and TF
When T1 is turned off, the gate of TFT1 and the display electrode 2
The potential of the display electrode 2 becomes ΔV
(DC level shift), the potential becomes Vd + −ΔV in the positive frame and Vd−−ΔV in the negative frame.

Accordingly, as shown in FIG. 5, the voltage applied to the liquid crystal during the accumulation period is Vd +-. DELTA.V-V in the positive frame.
c, and Vc−Vd−−ΔV in the negative frame, so that it becomes asymmetric between adjacent frames. In order to adjust this, conventionally, the common potential Vcom is adjusted to reduce the asymmetric component (DC component). However, since the capacitance of the liquid crystal changes according to the display data, the DC component is reduced over all the display data. It is impossible to eliminate them, and the reliability and display quality of the liquid crystal will be reduced.

On the other hand, in the liquid crystal display device according to the present embodiment, when a predetermined scan bus line 6 is selected, the TFT 3 connected to the scan bus line 6 together with the TFT 1 is turned on, as shown in FIG. As described above, Vcl is written to the common electrode 4 in the positive frame, and Vch is written in the negative frame. When the scan bus line 6 is not selected and the TFT 1 is turned off, the TFT 3 connected to the common electrode 4 is turned off almost simultaneously.

At this time, since the channel area of the TFT 1 connected to the display electrode 2 in each pixel region and the channel area of the TFT 3 connected to the common electrode 4 are substantially the same as described above, The capacitive coupling between the gate of the TFT 3 and the common electrode 4 is substantially the same as the capacitive coupling between the gate of the TFT 1 and the display electrode 2.

Therefore, the potential of the common electrode 4 becomes Vcl-.DELTA.V in the positive frame and Vch-.DELTA.V in the negative frame due to the DC level shift. The voltage applied to the liquid crystal is [potential of the display electrode 2] − [potential of the common electrode 4] (see the hatched portion in FIG. 4). Equal (Vd + -Vcl for positive frames, Vch-Vd- for negative frames) and can be symmetric between frames. Therefore, it is possible to easily perform the AC driving of the liquid crystal by almost completely removing the DC component. Therefore, display quality can be improved by preventing burning or the like,
Further, the reliability of the liquid crystal can be improved. Further, according to the structure of the present embodiment, the storage capacity can be reduced, so that the area of the storage capacity wiring or the like that shields the display area can be reduced, and the aperture ratio of the pixel can be improved. become.

Next, a modification of the configuration and the driving method of the liquid crystal display device according to the present embodiment will be described with reference to FIGS. In order to realize liquid crystal driving with the driving waveforms shown in FIG. 2 for each of the common bus lines 10 shown in FIG. 1, it is somewhat difficult that a new driving circuit is required because the driving waveforms are complicated. have. In order to solve this, in the modification shown in FIG. 6, each common bus line 10 is formed so as to be arranged in parallel with the scan bus line 6, and each common bus line 10 is connected to every other line. Common bus group (A) 10a and common bus group (B) 1
0b.

If a driving voltage as shown in FIG. 7 is applied to the modified example of the above configuration, simple and easy driving can be performed. FIG. 7A shows a common bus group (A) 10a when the scan bus line 6n is selected as an example.
2 shows a drive waveform applied to the drive. FIG. 7 (b)
Shows a drive waveform applied to the common bus group (B) 10b when the scan bus line 6n + 1 is selected as an example. As shown in FIG. 7, by supplying common potentials (Vcl, Vch) having opposite phases of positive and negative polarities for each frame to the common bus groups 10a and 10b, the polarities are reversed every horizontal scanning period. 1H inversion driving to be performed can be easily realized. In addition, it is possible to further simplify all common bus lines 6 into one group.

Next, another modification of the configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIGS. FIG. 8 shows an arrangement of each bus line on the array substrate surface, and FIG. 9 is an enlarged view of a region indicated by (α) in FIG. In this modification, one common bus line 10 is provided for two pixel regions adjacent to each other along the data bus line 8.
Is shown. As shown in FIGS. 8 and 9, the drain electrode (or source electrode) of the TFT 3 connected to the common electrode 4 of each pixel region is connected to one common bus line 10 (common bus line 10x in FIG. 9).
, The number of common bus lines in the display area can be reduced to half. Therefore, the aperture ratio of the display area can be improved.

Next, still another modification of the configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIGS. FIG. 10 shows an arrangement of each bus line on the array substrate surface, and FIG. 11 is an enlarged view of a region indicated by (β) in FIG. This modification shows a structure in which one common bus line 10 is allocated to two pixel regions adjacent to each other along the scan bus line 6. As shown in FIGS. 10 and 11, the drain electrode (or source electrode) of the TFT 3 connected to the common electrode 4 in each pixel region is connected to one common bus line 10 (common bus line 10y in FIG. 11). By letting
The number of common bus lines in the display area can be reduced by half. Therefore, the aperture ratio of the display area can be improved.

Next, still another modification of the configuration of the liquid crystal display device according to the present embodiment will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 12 shows an arrangement of each bus line on the array substrate surface, and FIG. 13 is an enlarged view of a region indicated by (γ) in FIG. The present modification uses a low-temperature polysilicon TFT manufacturing process, for example, to drive a scan bus drive circuit 20 for driving each scan bus line 6 and a data bus drive circuit 2 for driving each data bus line 8.
Second, it is characterized in that the common bus drive circuit 24 for driving the common data bus line 10 is formed integrally with a TFT using polysilicon as an operation semiconductor layer.

According to such a peripheral drive circuit integrated type liquid crystal display device, it is possible to reduce the manufacturing cost as compared with the related art. In addition, not only the structure in which the TFT 3 of each pixel region is connected to one common bus line 10 for each scan bus line 6 as shown in FIGS.
Also with the structure shown in FIGS. 8 to 11, it is possible to realize a peripheral drive circuit integrated type liquid crystal display device utilizing a low temperature polysilicon TFT manufacturing process or the like. In this case, in a configuration in which the common bus line 10 is parallel to the data bus line 8 as shown in FIGS. 10 and 11, the common bus drive circuit 24 is provided on the opposite side of the display area from the data bus drive circuit 22. It is desirable.

Next, another modification of the driving method of the liquid crystal display device according to the present embodiment will be described with reference to FIG. FIG. 14 shows a driving waveform of 1H inversion driving in the equivalent circuit shown in FIG. 1, and illustrates inversion driving of a common potential applied to each common electrode 4 of line numbers 1 to 6 among the scan bus lines 6. are doing. FIG.
By using the driving waveform shown in FIG.
The display quality can be further improved as compared with the driving method using the driving waveform shown in FIG.

In the case of the drive waveform shown in FIG. 7, the corresponding common potential Vcom switches in the opposite phase in accordance with the switching of the polarity of the data voltage Vd for each frame, but immediately after the switching of the common potential Vcom. The TFT 3 connected to the selected scan bus line 6 and the common potential Vc
scan bus line 6 selected immediately before om switching
The bias condition of the holding period (the non-selection period of the scan bus line) is different from that of the TFT 3 connected to.
TFT selected immediately before switching of common potential Vcom
3 is a more severe bias condition. For this reason, the margin for the off characteristic of the TFT 3 becomes stricter from the upper side to the lower side of the display area, and the luminance gradient in the image display is likely to occur.

On the other hand, the driving waveform shown in FIG. 14 corresponds to one horizontal scanning period (1
H), the inversion timing of the common potential Vcom is shifted by every time, so that all the TFTs 3 connected to each common electrode 4 under the gentlest condition as the bias condition of the holding period.
Can be operated. Therefore, it is possible to realize a liquid crystal display device having improved display quality without causing a luminance gradient.

As described above, according to the present embodiment, since the amplitude range of the data voltage Vd applied to the data bus line 8 can be reduced, a liquid crystal display device capable of reducing crosstalk and providing a good quality and bright display can be provided. realizable. Also,
Since the DC level shift is compensated for by the two TFTs 1 and 3, the AC drive can be easily realized and the display reliability can be improved. Further, by integrating the common bus drive circuit, display quality can be improved and cost can be reduced.

In view of the embodiments described above, it is possible to add the following requirements to each claim of the present invention in addition to the present requirements. That is, the first switching element formed in each pixel region on the array substrate according to the first aspect of the present invention includes the first switching element on the array substrate.
And a common electrode formed facing the display electrode for each pixel area on the array substrate, and a second switching element connected to the common electrode. In a liquid crystal display device,
The following configuration requirements can be added.

(1) Both the first switching element and the second switching element are thin film transistors, and the channel area of the first switching element and the channel area of the second switching element are substantially the same.

(2) At least a peripheral circuit for driving a common bus is provided on an insulating substrate so as to be integrated with a thin film transistor provided for each pixel.

(3) The first and second switching elements have an operating semiconductor layer mainly composed of polycrystalline silicon.

[0055]

As described above, according to the present invention, there is provided a liquid crystal display device which displays an image by controlling the orientation of liquid crystal by applying a voltage between a display electrode and a common electrode formed on an array substrate. Good display quality can be obtained with low power consumption.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing driving waveforms for describing a driving method of the liquid crystal display device according to one embodiment of the present invention.

FIG. 3 is a diagram showing a conventional driving method as a comparative example for explaining a driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 4 is a driving waveform diagram showing effects obtained from the configuration of the liquid crystal display device according to one embodiment of the present invention.

FIG. 5 is a diagram illustrating a conventional driving method as a comparative example, for explaining effects obtained from the configuration of the liquid crystal display device according to one embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the configuration and the driving method of the liquid crystal display device according to one embodiment of the present invention.

FIG. 7 is a diagram showing a modification of the configuration and the driving method of the liquid crystal display device according to one embodiment of the present invention.

FIG. 8 is a diagram showing another modification of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 9 is a diagram showing another modification of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 10 is a diagram showing still another modification of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 11 is a diagram showing still another modified example of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 12 is a diagram showing still another modification of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 13 is a diagram showing still another modification of the configuration and the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 14 is a diagram showing another modification of the driving method of the liquid crystal display device according to the embodiment of the present invention.

FIG. 15 is an equivalent circuit diagram showing a schematic configuration of a conventional in-plane switching mode liquid crystal display device.

[Explanation of symbols]

 1, 3 TFT 2 display electrode 4 common electrode 6 scan bus line 8 data bus line 10 common bus line 20 scan bus drive circuit 22 data bus drive circuit 24 common bus drive circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H092 GA14 JA24 JB14 JB42 JB46 NA01 NA07 NA26 PA06 QA06 2H093 NA16 NA32 NA33 NA43 NC18 NC34 NC40 ND12 ND15 ND22 ND35 ND39 NE03 NF04 5C006 AA22 AC28 AF44 BB16 BC05 FA05 FA05 FA05 FA05 FA05 CC03 DD03 DD26 DD27 FF11 JJ02 JJ03 JJ04 5C094 AA02 AA09 AA12 AA22 AA53 BA03 BA43 CA19 DA13 DB01 DB04 DB10 EA04 EA07 ED14 FA01 FB12 FB14 FB15 GA10

Claims (5)

[Claims] A first switching element formed in each pixel area on the array substrate; a display electrode connected to the first switching element on the array substrate; and a pixel area on the array substrate. A liquid crystal display device comprising: a common electrode formed so as to face the display electrode every time; and a second switching element connected to the common electrode. 2. The liquid crystal display device according to claim 1, further comprising: a plurality of common bus lines for supplying a common potential to the common electrode in the pixel area via the second switching element. A liquid crystal display device, wherein a plurality of common bus groups for connecting bus lines are formed. 3. The liquid crystal display device according to claim 2, wherein the plurality of common bus lines are formed in parallel with either a scan bus line or a data bus line, and the common bus lines are connected to every other line. A liquid crystal display device which is combined into a first common bus group and a second common bus group. 4. The liquid crystal display device according to claim 1, further comprising: a plurality of common bus lines for supplying a common potential to the common electrode in the pixel region via the second switching element. A liquid crystal display device, wherein one common bus line is allocated to two adjacent pixel regions along any of the data bus lines. 5. A switching element formed in each pixel region on an array substrate, a display electrode connected to the switching element on the array substrate, and a display electrode formed on the array substrate so as to face the display electrode. And a common electrode,
In a driving method of a liquid crystal display device that displays an image by controlling a liquid crystal orientation by an electric field of a component parallel to the array substrate surface by applying a voltage between the display electrode and the common electrode, A driving method for a liquid crystal display device, wherein the applied common potential takes two different potentials corresponding to the positive and negative polarities of the voltage applied to the liquid crystal.