JPH10221715A - Liquid crystal display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the influence of respective wires and adjacent pixel electrodes and to improve the display quality by providing a control electrode between pixel electrodes in the same layer. SOLUTION: The pixel electrodes 2 are driven by a 1H(one horizontal scanning period) inversion driving method which inverts the polarity in every 1H. Thus, adjacent pixel electrodes (vertical) are opposite in polarity, so a reverse tilt is easily generated at vertical end parts of each pixel electrode 2, specially, in the tilt direction of liquid crystal molecules, i.e., in a rubbing direction with an electric field produced laterally between upper and lower pixel electrodes 2. For the purpose, this liquid crystal display device applies a control electrode 11 with a signal having the same polarity with the pixel electrodes on the tilt-directional side of liquid crystal molecules of the control electrode 11. For example, when the top pixel electrode 2 is applied with a plus signal of approximately 0 to 5V, a plus signal of approximately 2.5V is applied to the control electrode 11a below it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for a display such as a computer or a television device and a method of driving the same, and particularly to a switching device such as a thin film transistor (hereinafter referred to as a TFT). And a method for driving the same.

[0002]

2. Description of the Related Art FIG. 11 shows an active matrix substrate constituting a conventional liquid crystal display device. FIG. 11 is a plan view showing a main part of a conventional active matrix substrate.

As shown in FIG. 11, on an active matrix substrate, a plurality of pixel electrodes 51 are provided in a matrix, and a plurality of pixel electrodes 51 pass around these pixel electrodes 51 and are orthogonally different from each other. A gate wiring 52 and a source wiring 53 are provided. Then, the gate wiring 52
A TFT 54 as a switching element connected to the pixel electrode 51 is provided near the intersection of the pixel electrode 51 and the source wiring 53.

A gate wiring 52 is connected to a gate electrode of the TFT 54, and the TFT 54 is driven and controlled by a signal input to the gate electrode. A source line 53 is connected to a source electrode of the TFT 54, and a data signal is input to the source electrode of the TFT 54. Then, the liquid crystal is sandwiched between a counter substrate having a counter electrode (not shown),
Display is performed by changing the transmittance of the liquid crystal according to the applied voltage.

The pixel electrode 51 and the additional capacitance wiring 55
Form an additional capacitance with a gate insulating film (not shown) interposed therebetween. Further, a light-shielding film 56 is formed so as to cover the periphery of the pixel electrode 51, thereby preventing light leakage from occurring between gaps between the respective wirings and the pixel electrode 51 and lowering the contrast.

In such a conventional liquid crystal display device, in addition to a vertical electric field generated between a peripheral portion of the pixel electrode 51 and a counter electrode, a gate line 52, a source line 53, and the adjacent pixel electrode 51 A so-called reverse tilt that affects the movement of liquid crystal molecules occurs due to the addition of a horizontal electric field generated therebetween, and a bright line occurs in the normally white mode,
In the normally black mode, black lines are generated and display quality is significantly deteriorated.

FIG. 12 is a cross-sectional view of a liquid crystal display device proposed in Japanese Patent Application Laid-Open No. 8-146386 to solve the above-mentioned problem. FIG. 12 is an explanatory view showing a cross section of a conventional liquid crystal display device.

As shown in FIG. 12, a control electrode 57 is arranged around the pixel electrode 51, and a signal is applied between the control electrode 57 and the counter electrode 58 so as to display black in a normally white mode, thereby causing the liquid crystal molecules to stand. A method of preventing reverse tilt has been proposed. Note that the portion where black display is performed using the control electrode 57 is shielded from light by the light shielding film 56, so that the display quality does not deteriorate.

[0009]

However, the above-described method is effective in preventing reverse tilt due to the influence of a horizontal electric field generated between each wiring and the pixel electrode. Such as a liquid crystal display device in which the aperture ratio is increased by interposing an interlayer insulating film between the adjacent pixel electrodes, and the effect of the electric field from the adjacent pixel electrode is large. The effect is insufficient.

This is because, in a normal liquid crystal display device, a reverse electric field caused by a horizontal electric field generated between each wiring and a pixel electrode, particularly an electric field generated between the wiring and a gate wiring, is caused by an electric field of a signal of the gate wiring. Since the control electrode is extremely high, the electric field is weakened by providing the control electrode closer to the pixel electrode than the gate wiring, so that the occurrence of reverse tilt can be reduced.

However, the distance between adjacent pixel electrodes is short, as in a liquid crystal display device or the like in which each wiring and a pixel electrode are overlapped via an interlayer insulating film to increase the aperture ratio. In a liquid crystal display device in which the influence of an electric field from the device is large, even if a control electrode is provided, the tilt is affected by the electric field from an adjacent pixel electrode, and a reverse tilt occurs.

In a liquid crystal display device in which each wiring and a pixel electrode are overlapped via an interlayer insulating film to increase the aperture ratio, each wiring and a pixel electrode are largely overlapped to hide a reverse tilt. Although a method is conceivable, there is a problem in that the parasitic capacitance between each wiring and the pixel electrode increases, and the display quality deteriorates due to the effect.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and a liquid crystal display device having a high aperture ratio by superposing each wiring and a pixel electrode via an interlayer insulating film. However, an object of the present invention is to provide a liquid crystal display device capable of preventing reverse tilt and improving display quality and a driving method thereof.

[0014]

According to a first aspect of the present invention, there is provided a liquid crystal display device comprising: a switching element provided near an intersection between a gate line and a source line; In a liquid crystal display device in which a wiring and the source wiring are overlapped with a pixel electrode via an interlayer insulating film, a control electrode is provided between the pixel electrodes in the same layer as the pixel electrode.

According to a second aspect of the present invention, there is provided a liquid crystal display device.
In the above liquid crystal display device, the control electrode is provided in parallel with the gate wiring.

According to a third aspect of the present invention, in the liquid crystal display device driving method, a switching element is provided near an intersection of the gate line and the source line, and a control electrode is provided between pixel electrodes controlled by the switching element. In the method for driving a display device, a signal having the same polarity as a signal applied to the pixel electrode provided on a tilt direction side of liquid crystal molecules of the control electrode is applied to the control electrode. I have.

According to a fourth aspect of the present invention, there is provided a method of driving a liquid crystal display device according to the third aspect.
The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period, and the polarity of the signal applied to the control electrode is inverted according to the inversion of the polarity of the signal applied to the pixel electrode. It is characterized by:

According to a fifth aspect of the present invention, there is provided a method of driving a liquid crystal display device according to the third aspect.
The polarity of the signal applied to the pixel electrode is inverted for each source line, and the polarity of the signal applied to the control electrode is inverted according to the inversion of the polarity of the signal applied to the pixel electrode. Features.

According to a sixth aspect of the present invention, there is provided a method of driving a liquid crystal display according to the third aspect.
The polarity of the signal applied to the pixel electrode is inverted for each horizontal scanning period and also for each source line,
The polarity of the signal applied to the control electrode is inverted according to the inversion of the polarity of the signal applied to the pixel electrode.

According to the liquid crystal display device of the present invention, in the liquid crystal display device in which the gate wiring and the source wiring and the pixel electrode are overlapped via the interlayer insulating film, the control electrode is provided between the pixel electrodes in the same layer as the pixel electrode. By being provided,
The horizontal electric field between the pixel electrode and the control electrode is stronger than the horizontal electric field between the pixel electrode and each wiring and between the adjacent pixel electrodes, and the influence of each wiring and the adjacent pixel electrode is reduced. Can be smaller.

In addition, since the control electrode is provided in parallel with the gate wiring, the gate wiring is generally formed wider for lowering the resistance, so that the leak between the pixel electrode and the control electrode is reduced. Can be done.

According to the driving method of the liquid crystal display device of the present invention, in the driving method of the liquid crystal display device in which the control electrode is provided between the pixel electrodes controlled by the switching elements, the tilt of the liquid crystal molecules of the control electrode is applied to the control electrode. The reverse tilt occurs in the tilt direction of the liquid crystal molecules, that is, in the rubbing direction, by applying a signal having the same polarity as the polarity of the signal applied to the pixel electrode provided on the direction side. Can be prevented.

The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period, and the polarity of the signal applied to the control electrode is inverted in accordance with the inversion of the polarity of the signal applied to the pixel electrode. By doing so, it is possible to reduce a reduction in display quality due to a parasitic capacitance generated between the pixel electrode and the source wiring while preventing reverse tilt.

The polarity of the signal applied to the pixel electrode is inverted for each source line, and the polarity of the signal applied to the control electrode is inverted in accordance with the inversion of the polarity of the signal applied to the pixel electrode. Thus, it is possible to reduce the degradation of the display quality due to the parasitic capacitance generated between the pixel electrode and the source wiring while preventing the reverse tilt.

The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period and also for each source line, and the polarity of the signal applied to the control electrode is
By inverting according to the inversion of the polarity of the signal applied to the pixel electrode, it is possible to reduce the degradation of display quality due to the parasitic capacitance generated between the pixel electrode and the source wiring while preventing reverse tilt. .

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1) FIG. 1 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device according to Embodiment 1, and FIG. 2 is a view A of the liquid crystal display device according to Embodiment 1 in FIG. It is sectional drawing in the -A line.

As shown in FIGS. 1 and 2, the active matrix substrate is formed on an insulating substrate 1 made of glass or the like, a transparent conductive film such as ITO in the case of a transmission type, and a metal such as aluminum in the case of a reflection type. A plurality of pixel electrodes 2 are arranged in a matrix, and a plurality of gate wirings 3 made of aluminum or tantalum are overlapped with the pixel electrodes 2.
And the source wiring 4 are provided so as to be orthogonal to each other and pass around the pixel electrode 2.

In the vicinity of the intersection between the gate line 3 and the source line 4, the pixel electrode 2 is connected to the pixel electrode 2 via a contact hole 6a provided in an interlayer insulating film 5 formed of a photosensitive acrylic resin or the like. A TFT 7 as a switching element is provided. A gate wiring 3 is connected to the gate electrode of the TFT 7, the TFT 7 is driven and controlled by a signal input to the gate electrode, and a source wiring 4 is connected to a source electrode of the TFT 7, and a data signal is supplied to a source electrode of the TFT 7. Is entered.

Further, the pixel electrode 2 and the additional capacitance electrode 8 are connected via a contact hole 6b, and an additional capacitance is formed between the pixel electrode 2 and the additional capacitance wiring 10 via a gate insulating film 9 therebetween. .

Further, a control electrode 11 is provided on a portion of the interlayer insulating film 5 above the gate wiring 3 between the adjacent pixel electrodes 2 (vertical direction in FIG. 1). Here, it is formed of the same material at the same time as the pixel electrode 2. Also, as described above, the control electrode 1
By forming 1 and the pixel electrode 2 in the same layer, a horizontal electric field between the adjacent pixel electrodes 2 can be effectively suppressed.

Then, an alignment film (not shown) is provided on the surface of a counter substrate 14 having a counter electrode 12 and a color filter 13 and an active matrix substrate, and a liquid crystal 15 is sandwiched between the two substrates.

The photosensitive acrylic resin constituting the interlayer insulating film 5 used here has a dielectric constant of 3.4 to 3.5, which is lower than that of the inorganic film (dielectric constant of silicon nitride: 8). Its transparency is high, and it is easily 3μm by spin coating method etc.
Gate wiring 3
And the capacitance between the source line 4 and the pixel electrode 2 can be reduced, and the capacitance component between the gate line 3 and the source line 4 and the pixel electrode 2 gives a display. Since the influence of crosstalk and the like can be further reduced, a favorable and bright display can be obtained.

Further, by using a photosensitive acrylic resin, a thick film can be formed by a spin coating method or the like, so that a thin film having a thickness as large as several μm can be easily formed. Is also unnecessary, which is advantageous in terms of productivity.

Here, the photosensitive acrylic resin used as the interlayer insulating film 5 is colored before coating.
After patterning, the entire surface can be subjected to an exposure process to make it more transparent. As described above, the transparentizing treatment of the resin can be performed not only optically but also chemically.

When such an interlayer insulating film 5 is used for a transmission type display device other than the photosensitive acrylic resin,
It is preferable to use a material having a low relative dielectric constant and high transparency, specifically, a material having a transmittance of 90% or more in a visible light region,
For example, polyamideimide, polyarylate, polyetherimide, epoxy, or highly transparent polyimide (for example, a combination of an acid dianhydride containing hexafluoropropylene and a diamine) can be used.

At this time, the human visibility is in the blue region (wavelength 4).
(500 to 500 nm) is slightly inferior, so that the use of a material having a spectral transmittance that is slightly inferior in the blue region is not inferior in a portion with high human eye visibility such as green or red, but coloring is conspicuous. Not desirable.

The polarity of the signal applied to the liquid crystal display according to the first embodiment will be described with reference to FIG. FIG.
FIG. 3 is an explanatory diagram showing polarities of signals applied to a pixel electrode and a control electrode according to the first embodiment.

The pixel electrode 2 is used for one horizontal scanning period (hereinafter, 1).
H) (indicated by H). In this method, the effect on the actual execution voltage applied to the liquid crystal is reduced by 1/5 to 1/1, even when the parasitic capacitance between the source line and the pixel electrode 2 is the same as compared with the field inversion driving method. It can be reduced to 10. The reason for this is that in the case of the 1H inversion driving method, the polarity of the data signal is inverted in a sufficiently short cycle with respect to the time of one field during one field. This is for canceling the influence of the and on the display.

As described above, since the polarities of the adjacent pixel electrodes 2 (vertical direction in FIG. 3) are opposite, the electric field generated in the horizontal direction between the vertical pixel electrodes 2 in FIG. 3, the vertical end portion, particularly the tilt direction of the liquid crystal molecules,
That is, reverse tilt is likely to occur in the rubbing direction.

Therefore, in the liquid crystal display device according to the first embodiment, a signal having the same polarity as that of the pixel electrode 2 on the tilt direction side of the liquid crystal molecules of the control electrode 11 is applied to the control electrode 11. That is, as shown in FIG. 3, when the rubbing direction of the alignment film on the active matrix substrate side is from the lower right to the upper left in FIG. 3, for example, 0 to 5 V is applied to the pixel electrode 2 in the uppermost part in FIG.
When a positive polarity signal of about 2.5 V is applied, a positive polarity signal of about 2.5 V is applied to the control electrode 11a thereunder. Then, -5 is applied to the pixel electrode 2 at the center of FIG.
A negative signal of about 0 V is applied, and a negative signal of about -2.5 V is applied to the control electrode 11b thereunder.

Such two signals can be easily realized, for example, by forming two or more wirings in parallel with the source wiring at the same time as the source wiring and inputting the signals to the wirings through the contact holes.

This driving method will be further described with reference to FIGS. FIG. 4 is an explanatory diagram illustrating an example of a method of driving the liquid crystal display device according to the first embodiment, and FIG. 5 is an explanatory diagram illustrating another example of a method of driving the liquid crystal display device according to the first embodiment.

As shown in FIG. 4, the scanning signals of the first row, the second row,...
The signal is turned off, a signal is applied to the pixel electrode accordingly, and the signal is held until the next signal is applied, that is, for one field period. The polarity of the pixel electrode signal is inverted between the odd and even rows.

For example, as shown in FIG. 3, when the rubbing is performed from the lower right to the upper left, the pixel electrodes 2 in the odd rows are rubbed.
A first control signal, which is a signal having the same polarity as that of the odd-numbered row of pixel electrodes 2, is applied to the control electrode 11 a below the even-numbered row, and a control electrode 11 b below the even-numbered row of pixel electrodes 2 is applied to the even-numbered row of the pixel electrodes 2. A second control signal having the same polarity as that of the pixel electrode 2 is applied. By driving in this manner, reverse tilt can be effectively suppressed.

As another example, as shown in FIG.
If the control signal is VGA, for example, rows 1 to 240 and 241
The signal is applied by dividing it into upper and lower halves of ８０480 rows. That is, the first control signal is applied to the odd-numbered control electrodes in the 1st to 240th rows, and the second control signal is applied to the even-numbered control electrodes in the 1st to 240th rows.
Apply control signal. Further, a third control signal is applied to the control electrodes of the odd-numbered rows of 241 to 480 rows,
The fourth control signal is applied to the control electrodes of the even rows.

The polarities of the first control signal and the second control signal are inverted in accordance with the scanning signal of the first row, that is, in accordance with the first signal of one field, and the signals are applied for one field period. It is kept as it is. Third control signal and fourth control signal
The polarity of the control signal is inverted in accordance with the scanning signal of the 241st row, that is, the lower half scanning signal.
The polarity is inverted again in accordance with the signal in the first row.

As described above, since the control signals are divided and applied, driving is performed in order from the first row, it is possible to match the actual polarity of the pixel electrode rather than changing the control signals all at once. In addition, reverse tilt can be prevented.

As described above, by applying the signal of the control electrode in accordance with the tilt direction of the liquid crystal molecules, that is, the rubbing direction, reverse tilt can be effectively prevented.

Here, only two types of signals applied to the control electrode are described: a method in which the signals are changed at once for each field period and a method in which the signals are applied in two upper and lower divisions. But it doesn't matter.

Also, the signal applied to the control electrode may be changed one by one simultaneously with the pixel electrode using a switching element, and the signal may be held for one field period similarly to the pixel electrode. As described above, if the values are divided and changed, control can be further performed in accordance with the polarity of the pixel electrodes.

The control signal ± 2.5
Not only a fixed signal such as V, but also an average signal of the row may be applied.

(Embodiment 2) FIG. 6 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device according to Embodiment 2, and FIG. 7 is a plan view of a liquid crystal display device according to Embodiment 2 in FIG. It is sectional drawing in the -B line. The description of the same parts as in the first embodiment will be simplified.

As shown in FIGS. 6 and 7, the active matrix substrate comprises a plurality of pixel electrodes 2 on an insulating substrate 1.
Are arranged in a matrix, and these pixel electrodes 2
A plurality of gate wirings 3 and source wirings 4 are provided so as to be orthogonal to each other and pass around the pixel electrode 2 so as to overlap with the pixel electrodes 2.

In the vicinity of the intersection of the gate line 3 and the source line 4, a TFT 7 as a switching element connected to the pixel electrode 2 is provided via a contact hole 6a provided in the interlayer insulating film 5. I have. The gate wiring 16 is connected to the gate electrode 16 of the TFT 7, and a signal is input to the gate electrode 16. On the other hand, the source line 4 and the source electrode 17 is connected through the semiconductor layer 19 through the n ⁺ layer 18, through the n ⁺ layer 18 and drain electrode 20, the data signal to the pixel electrode 2 are input.

Further, the pixel electrode 2 and the additional capacitance electrode 8 are connected via a contact hole 6 b, and an additional capacitance is formed between the pixel electrode 2 and the additional capacitance wiring 10 via a gate insulating film 9. .

Further, a control electrode 11 is provided on the portion of the interlayer insulating film 5 above the source wiring 4 between the adjacent pixel electrodes 2 (in the horizontal direction in FIG. 6). Here, it is formed of the same material at the same time as the pixel electrode 2. Also, as described above, the control electrode 1
By forming 1 and the pixel electrode 2 in the same layer, a horizontal electric field between the adjacent pixel electrodes 2 can be effectively suppressed.

Then, an orientation film (not shown) is provided on the surface of the opposing substrate 14 having the opposing electrode 12 and the color filter 13 and the active matrix substrate, and the liquid crystal 15 is sandwiched between both substrates.

The polarity of the signal applied to the liquid crystal display according to the second embodiment will be described with reference to FIG. FIG.
FIG. 9 is an explanatory diagram showing polarities of signals applied to a pixel electrode and a control electrode according to the second embodiment.

The pixel electrode 2 is driven by a source line inversion driving method in which the polarity is inverted for each source wiring. In this method, since signals of opposite polarities are input to adjacent source lines, a parasitic capacitance that can overlap the source line and the pixel electrode 2 is canceled in the left-right direction in FIG. Therefore, the same parasitic capacitance has little effect on display.

As described above, since the adjacent pixel electrodes 2 (horizontal direction in FIG. 8) have opposite polarities, the electric field generated in the horizontal direction between the horizontal pixel electrodes 2 in FIG. 8, the end portion in the left-right direction, particularly the tilt direction of the liquid crystal molecules,
That is, reverse tilt is likely to occur in the rubbing direction.

Therefore, in the liquid crystal display device according to the second embodiment, a signal having the same polarity as that of the pixel electrode 2 on the tilt direction side of the liquid crystal molecules of the control electrode 11 is applied to the control electrode 11. That is, as shown in FIG. 8, when the rubbing direction of the alignment film on the active matrix substrate side is from the lower right to the upper left in FIG. 8, for example, 0-5 V is applied to the pixel electrode 2 in the leftmost part in FIG.
When a signal having a positive polarity of about 2.5 V is applied, a signal having a positive polarity of about 2.5 V is applied to the right control electrode 11 a. Then, a negative signal of about −5 to 0 V is applied to the pixel electrode 2 in the second column from the left in FIG. 8, and a negative signal of about −2.5 V is applied to the right control electrode 11 b. You.

Such two signals can be easily realized by, for example, forming two or more wirings in parallel with the gate wiring at the same time as the gate wiring, and inputting a signal to the wiring through a contact hole.

As described above, similarly to the first embodiment, reverse tilt can be effectively prevented by applying a signal from the control electrode in accordance with the tilt direction of the liquid crystal molecules, that is, the rubbing direction.

As in the first embodiment, the control electrodes may be divided into a plurality of blocks, such as upper and lower blocks, and may be driven to perform control in accordance with the signals of the actual pixel electrodes.

(Embodiment 3) FIG. 9 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device according to Embodiment 3. The description of the same parts as in the first and second embodiments will be simplified.

As shown in FIG. 9, the active matrix substrate includes a plurality of pixel electrodes 2 arranged in a matrix on an insulating substrate, and a plurality of gate wirings 3 overlapping the pixel electrodes 2. And the source wiring 4 are provided so as to be orthogonal to each other and pass around the pixel electrode 2.

In the vicinity of the intersection between the gate line 3 and the source line 4, a TFT 7 as a switching element connected to the pixel electrode 2 is provided via a contact hole 6a provided in an interlayer insulating film. .

Further, the pixel electrode 2 and the additional capacitance electrode 8 are connected via a contact hole 6b, and an additional capacitance is formed between the pixel electrode 2 and the additional capacitance wiring 10 via a gate insulating film.

Further, a control electrode 11 is provided on a portion of the interlayer insulating film above the gate wiring 3 and the source wiring 4 between the adjacent pixel electrodes 2 (in the vertical and horizontal directions in FIG. 9). To explain using one pixel electrode 2, the control electrode 11 is provided so as to pass upward and leftward in FIG. 9 of the pixel electrode 2, and another control electrode 11 is provided in FIG. It is provided to pass rightward and downward. Thus, the control electrode 11 is provided so as to surround the periphery of one pixel electrode 2. Here, it is formed of the same material at the same time as the pixel electrode 2. Further, by forming the control electrode 11 and the pixel electrode 2 in the same layer as described above, the horizontal electric field between the adjacent pixel electrodes 2 can be effectively suppressed.

Then, an orientation film (not shown) is provided on the surface of the counter substrate provided with the counter electrode and the color filter, and the active matrix substrate, and liquid crystal is sandwiched between the two substrates.

The polarity of the signal applied to the liquid crystal display according to the third embodiment will be described with reference to FIG. FIG. 10 is an explanatory diagram showing the polarities of signals applied to the pixel electrode and the control electrode according to the third embodiment.

In the third embodiment, as a driving method of the pixel electrode 2, the adjacent pixel electrode 2 (in the vertical and horizontal directions in FIG. 10)
The dot inversion driving method in which the polarities of the signals are different from each other is used.
In accordance with this driving method, the control electrode 11 is provided so as to meander in accordance with the polarity of each pixel electrode 2.

The pixel electrode 2 is driven by a dot inversion driving method in which the polarity is inverted every source line and every 1H. In this driving method, signals of opposite polarities are input to adjacent source wirings and the polarity is inverted every 1H.
Even with the same parasitic capacitance, the effect on the display can be minimized.

As described above, the adjacent pixel electrode 2 (FIG. 10)
(Up, down, left, and right directions), the electric field generated in the horizontal direction between the pixel electrodes 2 in the up, down, left, and right directions in FIG. 10 causes the end portions of each pixel electrode 2 in the up, down, left, and right directions in FIG. , The reverse tilt is likely to occur in the rubbing direction.

Therefore, in the liquid crystal display device according to the third embodiment, a signal having the same polarity as that of the pixel electrode 2 on the tilt direction side of the liquid crystal molecules of the control electrode 11 is applied to the control electrode 11. That is, as shown in FIG. 10, when the rubbing direction of the alignment film on the active matrix substrate side is from the lower right to the upper left in FIG. 10, for example, 0-5 V is applied to the pixel electrode 2 in the upper left portion in FIG.
When a positive signal of about 2.5 V is applied, a positive signal of about 2.5 V is applied to the lower right control electrode 11a. The right and lower pixel electrodes 2 in the upper left portion
A negative signal of about -5 to 0 V is applied, and a negative signal of about -2.5 V is applied to the lower right control electrode 11b.

For such two signals, for example, two or more wirings are formed in parallel with the gate wiring and the source wiring at the same time as the gate wiring and the source wiring, and a signal is input to the wiring through a contact hole. Can be easily realized.

As described above, similarly to the first and second embodiments, the reverse tilt is effectively prevented by applying the signal of the control electrode in accordance with the tilt direction of the liquid crystal molecules, that is, the rubbing direction. be able to.

As in the first embodiment, the control electrodes may be divided into a plurality of blocks, such as upper and lower blocks, and driven to perform control in accordance with the actual signal of the pixel electrodes.

Although the control electrodes are provided on both the gate wiring and the source wiring here, the gate wiring is generally formed to have a large wiring width in order to reduce the resistance, and the source wiring is formed to have a smaller wiring width. I have. Therefore, when the source wiring is very thin and the control electrode is not provided on the source wiring,
The control electrode may be formed only on the gate wiring.
In that case, the display quality is improved by slightly increasing the overlap between the source wiring and the pixel electrode.

In the embodiment of the present invention, the case where the pixel electrode and the control electrode are formed in the same layer has been described. However, according to the driving method of the liquid crystal display device of the present invention,
Similar effects can be obtained even when the pixel electrode and the control electrode are formed in different layers.

[0082]

As described above, according to the liquid crystal display device of the present invention, in the liquid crystal display device in which the gate wiring and the source wiring and the pixel electrode are overlapped via the interlayer insulating film, the same as the pixel electrode. Since the control electrode is provided between the one pixel electrode, the influence of each wiring and the adjacent pixel electrode can be reduced, and the display quality can be improved.

Further, since the control electrode is provided in parallel with the gate wiring, the leak between the pixel electrode and the control electrode can be reduced, and the yield rate can be improved.

According to the driving method of the liquid crystal display device of the present invention, in the driving method of the liquid crystal display device in which the control electrode is provided between the pixel electrodes controlled by the switching elements, the tilt of the liquid crystal molecules of the control electrode is applied to the control electrode. By applying a signal having the same polarity as the polarity of the signal applied to the pixel electrode provided on the direction side, reverse tilt can be effectively prevented, and display quality can be improved.

The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period, and the polarity of the signal applied to the control electrode is inverted according to the inversion of the polarity of the signal applied to the pixel electrode. By doing so, it is possible to reduce a reduction in display quality due to a parasitic capacitance generated between the pixel electrode and the source wiring while preventing reverse tilt.

The polarity of the signal applied to the pixel electrode is inverted for each source line, and the polarity of the signal applied to the control electrode is inverted according to the inversion of the polarity of the signal applied to the pixel electrode. Thus, it is possible to reduce the degradation of the display quality due to the parasitic capacitance generated between the pixel electrode and the source wiring while preventing the reverse tilt.

The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period and also for each source line, and the polarity of the signal applied to the control electrode is
By inverting according to the inversion of the polarity of the signal applied to the pixel electrode, it is possible to reduce the degradation of display quality due to the parasitic capacitance generated between the pixel electrode and the source wiring while preventing reverse tilt. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device according to a first embodiment.

FIG. 2 is a cross-sectional view of the liquid crystal display device according to the first embodiment taken along line AA in FIG.

FIG. 3 is an explanatory diagram illustrating polarities of signals applied to a pixel electrode and a control electrode according to the first embodiment;

FIG. 4 is an explanatory diagram illustrating an example of a driving method of the liquid crystal display device according to the first embodiment.

FIG. 5 is an explanatory diagram showing another example of a method for driving the liquid crystal display device according to the first embodiment.

FIG. 6 is a plan view showing a main part of an active matrix substrate of the liquid crystal display device according to the second embodiment.

FIG. 7 is a cross-sectional view of the liquid crystal display device according to the second embodiment taken along line BB in FIG.

FIG. 8 is an explanatory diagram showing polarities of signals applied to a pixel electrode and a control electrode according to the second embodiment.

FIG. 9 is a plan view showing a main part of an active matrix substrate of a liquid crystal display device according to a third embodiment.

FIG. 10 is an explanatory diagram illustrating polarities of signals applied to a pixel electrode and a control electrode according to the third embodiment.

FIG. 11 is a plan view showing a main part of a conventional active matrix substrate.

FIG. 12 is an explanatory view showing a cross section of a conventional liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Pixel electrode 3 Gate wiring 4 Source wiring 5 Interlayer insulating film 6a, 6b Contact hole 7 TFT 8 Additional capacitance electrode 9 Gate insulating film 10 Additional capacitance wiring 11 Control electrode 11a Control by applying signal of positive polarity Electrode 11b Control electrode to which negative signal is applied 12 Counter electrode 13 Color filter 14 Counter substrate 15 Liquid crystal 16 Gate electrode 17 Source electrode 18 n ⁺ layer 19 Semiconductor layer 20 Drain electrode 51 Pixel electrode 52 Gate wiring 53 Source wiring 54 TFT 55 Wiring for additional capacitance 56 Shielding film 57 Control electrode 58 Counter electrode

Claims (6)

[Claims] In a liquid crystal display device, a switching element is provided near an intersection of a gate line and a source line, and the gate line and the source line overlap a pixel electrode via an interlayer insulating film. A liquid crystal display device, wherein a control electrode is provided between the pixel electrodes in the same layer as the electrodes. 2. The liquid crystal display device according to claim 1, wherein said control electrode is provided in parallel with said gate wiring. 3. A driving method of a liquid crystal display device, wherein a switching element is provided near an intersection of a gate wiring and a source wiring, and a control electrode is provided between pixel electrodes controlled by the switching element. And a signal having the same polarity as that of a signal applied to the pixel electrode provided on a tilt direction side of liquid crystal molecules of the control electrode. 4. The polarity of the signal applied to the pixel electrode is inverted every horizontal scanning period, and the polarity of the signal applied to the control electrode is inverted with the polarity of the signal applied to the pixel electrode. 4. The method according to claim 3, wherein the inversion is performed together.
The driving method of the liquid crystal display device according to the above. 5. The polarity of a signal applied to the pixel electrode is inverted for each source line, and the polarity of a signal applied to the control electrode is adjusted in accordance with the inversion of the polarity of a signal applied to the pixel electrode. 4. The method according to claim 3, wherein the liquid crystal display device is inverted. 6. The polarity of a signal applied to the pixel electrode is inverted every horizontal scanning period and also for each source line, and the polarity of a signal applied to the control electrode is equal to the polarity of the pixel electrode. 4. The method according to claim 3, wherein the signal is inverted in accordance with the inversion of the polarity of the signal applied to the liquid crystal display device.