JPH11258624A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which has its display quality improved by preventing the opposite substrate from being charged electrostatically and suppressing a liquid crystal abnormal area and a liquid crystal display device which is improved in the response speed of liquid crystal molecules in the transition from an ON state to an OFF state. SOLUTION: An array substrate 100 is equipped with pixel electrodes 151A and a common electrode 204A and an opposite substrate 200 is equipped with pixel electrodes 151B and a common electrode 204B. The pixel electrodes 151B and common electrode 204B are applied with a voltage controlled by TFT 121B independently of a voltage applied to the pixel electrodes 151A and common electrode 204A. A liquid crystal composition 300 contains liquid crystal molecules 302 which are displaced in a specific direction while a lateral electric field is produced with the voltage applied to the pixel electrodes 151A and common electrode 204A and a chiral substance which imparts a displacing force for displacement in the opposite direction from a given direction to the liquid crystal molecules 302.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display, and more particularly, to an in-plane switching liquid crystal mode liquid crystal display mainly using an electric field substantially parallel to a display plane.

[0002]

2. Description of the Related Art In recent years, a liquid crystal composition sandwiched between substrates is controlled by utilizing a vertical electric field formed between electrodes disposed on two substrates disposed opposite to each other at a predetermined interval. In addition to the liquid crystal display device, a horizontal electric field control type liquid crystal display device mainly using a horizontal electric field formed between two kinds of electrodes arranged in parallel with one substrate only, that is, an in-plane switching type liquid crystal Mode or IP
Liquid crystal display devices utilizing the S mode have been put to practical use.

The IPS liquid crystal display device has an array substrate provided with a thin film transistor as a switching element, ie, a TFT, a pixel electrode, and a common electrode, and a counter substrate on which no electrode is formed. The IPS liquid crystal display device is driven by rotating liquid crystal molecules contained in the liquid crystal composition in a plane parallel to the array substrate by a voltage difference between the pixel electrode and the common electrode, and changing the alignment state. Is what you do.

Such an IPS liquid crystal display device has good viewing angle characteristics as compared with a liquid crystal display device using a vertical electric field, and also has a good viewing angle when viewed from the normal direction of the substrate and when viewed from an oblique direction. Is characterized by a small difference in color and contrast.

[0005]

In the above-described lateral electric field control type liquid crystal display device, since a conductive material such as an electrode is not disposed on the counter substrate side, the counter substrate is in a so-called floating state. Electric charge is easily accumulated and easily charged. The liquid crystal molecules contained in the liquid crystal composition change their alignment state in response to an electric field formed between the pixel electrode provided on the array substrate side and the common electrode, and are driven.

However, when electric charges are accumulated on the counter substrate side, the electric charges form an electric field irrelevant to the driving of the liquid crystal molecules, so that the alignment state of the liquid crystal molecules is disturbed, which may cause display failure.

Further, in this lateral electric field control type liquid crystal display device, a lateral electric field substantially parallel to a substrate formed between a pixel electrode and a common electrode is mainly used. A strong horizontal electric field is formed near the array substrate on which the pixel electrode and the common electrode are provided, but a vertical electric field is formed near the electrodes while the horizontal electric field is weakened on the side of the opposing substrate which is far from these electrodes. . In the region where the horizontal electric field is weak near the electrodes, the liquid crystal molecules cannot be driven sufficiently. In the region where the vertical electric field is formed near the electrodes, the alignment state of the liquid crystal molecules is in a direction irrelevant to the driving of the liquid crystal molecules. Disturbed.

As described above, by forming a region where the horizontal electric field is weak or a region where the vertical electric field is formed, a region where the liquid crystal molecules cannot be sufficiently driven or a region where the alignment state of the liquid crystal molecules is disturbed, that is, a liquid crystal abnormality An area is formed. In such a liquid crystal abnormal region, there is a problem that a display failure occurs.

As described above, a display defect of the liquid crystal display device is deteriorated due to a display defect due to the charging of the counter substrate and a display defect due to the occurrence of the abnormal liquid crystal region.

[0010] Further, in this horizontal electric field control type liquid crystal display device, there is a problem that the response speed of liquid crystal molecules is slower than that of a chanting display device using a vertical electric field. Since the response speed of the liquid crystal molecules when transitioning from the off state to the on state by forming a horizontal electric field depends on the electric field intensity, it is possible to improve the response speed by increasing the electric field intensity. However, the response speed of the liquid crystal molecules when transitioning from the on state to the off state is determined only by the alignment control force of the alignment films provided on the array substrate and the counter substrate, and therefore the response speed cannot be improved. There is a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device in which the counter substrate is prevented from being charged and a display quality is improved by suppressing a liquid crystal abnormal region. And

The present invention also provides a response speed of liquid crystal molecules,
In particular, it is an object of the present invention to provide a liquid crystal display device in which the response speed of liquid crystal molecules when shifting from an on state to an off state is improved.

[0013]

SUMMARY OF THE INVENTION The present invention has been made based on the above problems. According to the present invention, there is provided an array substrate, a counter substrate disposed to face the array substrate, and an array substrate. In a liquid crystal display device comprising a liquid crystal composition sandwiched between a counter substrate, the array substrate,
A first electrode disposed on one main surface of the substrate, a second electrode disposed at a predetermined distance from the first electrode, and a switching element for controlling a voltage applied to the first electrode; A third electrode disposed on one main surface of the substrate and facing the first electrode;
A fourth electrode disposed at a predetermined distance from the third electrode and facing the second electrode;
A liquid crystal display device, comprising: a voltage supply unit that supplies a voltage controlled independently of a voltage applied to the first electrode and the second electrode to the electrode and the fourth electrode. Is provided.

Further, according to claim 5, an array substrate,
In a liquid crystal display device including a counter substrate disposed to face the array substrate and a liquid crystal composition sandwiched between the array substrate and the counter substrate, the array substrate is disposed on one main surface of the substrate. A first electrode, a second electrode disposed at a predetermined distance from the first electrode, and a switching element for controlling a voltage applied to the first electrode. A liquid crystal molecule that is displaced in a predetermined direction in a state where an electric field is formed by a voltage applied to the first electrode and the second electrode, and a displacement force that displaces the liquid crystal molecule in a direction opposite to the predetermined direction. And a chiral substance to be provided.

According to the liquid crystal display device of the first aspect,
Providing a first electrode and a second electrode on the array substrate;
A third electrode and a fourth electrode are provided on the counter substrate. Third
A voltage controlled independently of a voltage applied to the first electrode and the second electrode is supplied to the electrode and the fourth electrode by a voltage supply unit. As described above, by providing the third and fourth electrodes on the counter substrate side, it is possible to prevent charges from being accumulated and charged on the counter substrate.

Further, it is possible to form a horizontal electric field at least between the first electrode and the second electrode and between the third electrode and the fourth electrode. , A strong horizontal electric field can be formed.

This solves the problem that a region having a weak horizontal electric field is formed near the counter substrate or a vertical electric field is formed near the electrode, and the occurrence of an abnormal liquid crystal region can be suppressed. Therefore, it is possible to provide a liquid crystal display device with improved display quality by preventing charging of the opposing substrate and suppressing occurrence of a liquid crystal abnormal region.

Further, according to claim 5, the liquid crystal composition comprises:
Liquid crystal molecules that are displaced in a predetermined direction in a state where an electric field is formed by a voltage applied to the first electrode and the second electrode, and a chiral that applies a displacement force to displace the liquid crystal molecules in a direction opposite to the predetermined direction. By including the substance, it is possible to quickly displace the liquid crystal molecules to the off state by the displacement force of the chiral substance when transitioning from the on state where the electric field is formed to the off state. Therefore, it is possible to provide a liquid crystal display device having improved response speed of liquid crystal molecules.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the liquid crystal display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view schematically showing an example of a liquid crystal display panel applied to the liquid crystal display device of the present invention.

A liquid crystal display device according to an embodiment of the present invention is a lateral electric field control type liquid crystal display device of an active matrix driving system which is provided with a display area of, for example, 15 inches diagonally. A liquid crystal display panel 10 as shown is provided.

As shown in FIG. 1, the liquid crystal display panel 10 includes an array substrate 100 as a first substrate including a display area 102 for displaying an image and a peripheral area 104 on which a wiring pattern is formed. And the display area 102 of the array substrate 100.
And a liquid crystal composition disposed between the array substrate 100 and the opposing substrate 200 as a second substrate having a display area corresponding to. Display area 1
Numeral 02 is formed in a region surrounded by a seal material 106 for bonding the array substrate 100 and the counter substrate 200, and a peripheral area 104 is formed in a region outside the seal material 106.

FIG. 2 is a plan view schematically showing a counter substrate and an array substrate applied to the liquid crystal display panel shown in FIG. 1, and FIG. 3 is a plan view of the substrate shown in FIG. It is sectional drawing which cut | disconnected.

As shown in FIG. 3, a liquid crystal display device 10 according to the present embodiment has an array substrate 100, a counter substrate 200 arranged opposite to the array substrate 100, and a gap between the array substrate 100 and the counter substrate 200. And a liquid crystal composition 300 arranged on the substrate.

The array substrate 100 and the counter substrate 200
Is a substrate applied to an in-plane-switching type liquid crystal mode, that is, an IPS liquid crystal mode liquid crystal display device. That is, the array substrate 100 and the counter substrate 200 applied to the IPS liquid crystal display device have a common electrode and a pixel electrode, respectively, which are arranged on the same insulating substrate such as glass.

In this IPS liquid crystal display device, a horizontal electric field substantially parallel to the array substrate is formed by the potential difference between the common electrode and the pixel electrode disposed on the array substrate 100 side, and the horizontal electric field is disposed on the counter substrate 200 side. A horizontal electric field substantially parallel to the counter substrate is formed by the potential difference formed between the common electrode and the pixel electrode. Then, by rotating the liquid crystal molecules included in the liquid crystal composition 300 disposed between the array substrate 100 and the counter substrate 200 in a plane parallel to the substrate, the liquid crystal molecules are driven while changing the alignment state of the liquid crystal molecules.

As shown in FIGS. 2 and 3, the array substrate 1
The display area 102 is composed of 1024 × 3 signal lines 103 A and 7, which are arranged orthogonally to each other on an insulating substrate, for example, a glass substrate 101 having a thickness of 0.7 mm.
It has 68 scanning lines 111A. Scanning line 111A
Is formed of a low-resistance material such as aluminum or a molybdenum-tungsten alloy, and is directly provided on the glass substrate 101. On the other hand, the signal line 10
3A is formed in a laminated structure of molybdenum / aluminum / molybdenum, and is disposed on an insulating film 113A formed on the glass substrate 101 and formed of a multilayer film of silicon oxide and silicon nitride.

The array substrate 100 is provided with each signal line 10
It includes a thin film transistor or TFT 121A as a switching element disposed near each intersection of 3A and each scanning line 111A, a pixel electrode 151A connected via the TFT 121A, and a common electrode 204A. The common electrode 204A is provided directly on the same layer as the scanning line 111A, that is, on the glass substrate 101.
The pixel electrode 151A is provided on the same layer as the signal line 103A, that is, on the insulating film 113A.

The TFT 121A uses the scanning line 111A itself as a gate electrode, and a hydrogenated amorphous silicon semiconductor layer, ie, a-Si: H, disposed via a silicon nitride film, ie, a gate insulating film 113A made of SiNx.
115A. Further, a channel protective film 117A formed of silicon nitride is stacked on the semiconductor layer 115A formed of a-Si: H.

The TFT 121A is made of a low-resistance hydrogen-doped amorphous silicon semiconductor film doped with phosphorus, that is, an n + type a-
Low resistance semiconductor film 119A formed of a Si: H film
Have a source electrode 131A and a drain electrode 132A that are electrically connected to the semiconductor film 115A via the gate electrode 131A.

The drain electrode 132A is connected to the signal line 103A.
It is configured integrally with. The source electrode 131A is connected to the signal line 1
Similar to 03A, it is formed in a laminated structure of molybdenum / aluminum / molybdenum, and extends along the signal line 103A on the stripe so as to constitute the pixel electrode 151A. An end portion of the pixel electrode 151A forms a first auxiliary capacitance electrode portion 273A for forming an auxiliary capacitance Cs.

The common electrode 204A is formed of a molybdenum-tungsten alloy similarly to the scanning line 111A.
It is arranged substantially parallel to the scanning line 111A. The common electrode 204A is provided with a first auxiliary capacitance electrode portion 273A and a second auxiliary capacitance overlapping with the first auxiliary capacitance electrode portion 273A via the gate insulating film 113A, which are wired substantially parallel to the pixel electrode 151A. And an electrode portion 207A.

The surface of the array substrate 100 is covered with an alignment film 141A for aligning liquid crystal molecules contained in the liquid crystal composition 300 interposed between the array substrate 100 and the counter substrate 200.

With such a configuration, the pixel electrode 151A
And the first electrode portion 205A of the common electrode 204A, and between the pixel electrode 151A and the second electrode portion 20A of the common electrode 204A.
A horizontal electric field substantially parallel to the array substrate 100 is formed by the potential difference between the array substrate 100A and the array substrate 100. The liquid crystal molecules are controlled according to the intensity of the electric field.

In the liquid crystal display panel 100, as shown in FIG. 1, in order to reduce the outer dimensions of the liquid crystal display device, particularly the frame size, the signal lines are not shown in detail but are arranged around the array substrate 100. X-TABs 401-1 and 401-4 which are drawn out only to the first side 201 side of the area 104 </ b> Y and supply video data to signal lines on the first side 201 side
01-2, 401-3, and 401-4 via an anisotropic conductive adhesive.

The scanning lines are also arranged on the second side 2 orthogonal to the first side 201 in the peripheral area 104Y of the array substrate.
Y-TAB 411-1, 41 which are drawn out only to the side 03 and supply scanning pulses to the scanning lines on the side of the second end side 203.
1-2 are connected via an anisotropic conductive adhesive.

Then, X-TABs 401-1 and 401-
Reference numerals 2, 401-3, and 401-4 denote the X-TABs 401-1, 401-2, and 401 which are bent toward the rear surface of the liquid crystal display panel 10 and disposed on the rear surface of the liquid crystal display panel 10.
-3 and 401-4 are connected to an X control circuit board 421 via an anisotropic conductive adhesive.

Further, Y-TAB 411-1, 411-2
Are arranged on the sides of the liquid crystal display panel 10 and each Y-TA
Y control circuit board 4 for controlling B411-1 and 411-2
31 is connected via an anisotropic conductive adhesive. Note that each of the X-TABs 401-1, 401-2, 401-3, 40
1-4 and the X control circuit board 421 or each Y-TA
The electrical connection between the B 411-1 and 411-2 and the Y control circuit board 431 may be by soldering.

The display area 102 of the counter substrate 200 is, as shown in FIG.
It is configured similarly to. That is, it includes 1024 × 3 signal lines 103B and 768 scanning lines 111B arranged orthogonally to each other on a transparent insulating substrate, for example, a glass substrate 201 having a thickness of 0.7 mm. .

A thin film transistor, ie, a TFT 121B is provided near each intersection of each signal line 103B and each scanning line 111B as a switching element, and the pixel electrode 1 connected via this TFT 121A is provided.
51B and a common electrode 204B are provided. The common electrode 204B is provided directly on the same layer as the scanning line 111B, that is, on the glass substrate 201. The pixel electrode 151B is provided on the same layer as the signal line 103B, that is, over the insulating film 113B.

The TFT 121B has a semiconductor layer 115B disposed with a gate insulating film 113B with the scanning line 111B itself as a gate electrode. Further, a channel protective film 117B is stacked on the semiconductor layer 115B.

The TFT 121B has a source electrode 131B and a drain electrode 132B electrically connected to the semiconductor film 115B via the low-resistance semiconductor film 119B.

The drain electrode 132B is connected to the signal line 103B.
It is configured integrally with. The source electrode 131B is formed on the signal line 103 on the stripe so as to form the pixel electrode 151B.
It extends along B. An end of the pixel electrode 151B forms a first auxiliary capacitance electrode portion 273B for forming the auxiliary capacitance Cs.

The common electrode 204B is arranged substantially parallel to the scanning line 111B. The common electrode 204B includes a first electrode portion 205B and a second electrode portion 206B which are wired substantially parallel to the pixel electrode 151B, and a first auxiliary capacitance electrode portion 273B.
And a second auxiliary capacitance electrode portion 207B overlapping with the gate insulating film 113B interposed therebetween.

The surface of the counter substrate 200 is covered with an alignment film 141B for aligning liquid crystal molecules contained in the liquid crystal composition 300 interposed between the counter substrate 200 and the array substrate 100.

With such a configuration, the pixel electrode 151B
And the first electrode portion 205B of the common electrode 204B, and between the pixel electrode 151B and the second electrode portion 20 of the common electrode 204B.
6B, a horizontal electric field substantially parallel to the counter substrate 200 is formed. And according to the strength of this electric field,
Controls liquid crystal molecules.

Various wirings such as the scanning lines 111 B and the signal lines 103 B on the counter substrate 200 are
It is electrically connected to the array substrate 100 by a conductive paste (transfer) (not shown) interposed between the substrate and the counter substrate 200. A signal voltage that can be controlled independently of a signal voltage supplied to the array substrate side can be supplied to these various wirings.

That is, the pixel electrode 151B and the common electrode 204B provided on the counter substrate 200 are brought to a predetermined level by the TFT 121B as a voltage supply means which can be controlled independently of the TFT 121A provided on the array substrate 100 side. A controlled voltage is provided. In this embodiment, the pixel electrode 151B on the counter substrate 200 side is used.
The TFT 121B is provided on the counter substrate 200 side as a voltage supply means for supplying a voltage to the common electrode 204B, but other means may be used as long as independently controlled voltages can be supplied to the pixel electrode 151B and the common electrode 204B. You may.

The voltage value supplied to the pixel electrode 151B and the common electrode 204B will be described later. The array substrate 100 and the opposing substrate 200 as described above are
The liquid crystal display panel 10 is formed by laminating at a predetermined interval by 6. Array substrate 100
A spacer (not shown) is provided between the substrate and the counter substrate 200, and the distance between the substrates is maintained at about 3.5 μm. The gap between the substrates has a positive dielectric anisotropy of 1
Having a value of 0.7, a refractive index anisotropy of 0.10 and a viscosity of 2
A liquid crystal layer 300 containing a 1 cps nematic liquid crystal material is held.

The liquid crystal molecules contained in the liquid crystal layer 300 are maintained in an alignment state that matches the alignment processing directions of the alignment films 141A and 141B of the array substrate 100 and the counter substrate 200.

On the outer surfaces of the array substrate 100 and the counter substrate 200, polarizing plates 431 and 441 respectively transmitting only a light beam having a predetermined deflecting surface are arranged.
In the horizontal electric field control type liquid crystal display device configured as described above, as shown in FIG. 4A, the liquid crystal layer, that is, the liquid crystal composition 300 includes the array substrate 100 and the counter substrate 200.
It is held via alignment films 141A and 141B that are aligned in the same direction. The orientation direction R of the orientation films 141A and 141B is a predetermined angle θ1 with respect to the direction E of the electric field between the pixel electrode 151 and the common electrode 204.
For example, it forms 45 °.

The polarization planes of the polarizing plates 431 and 441 provided on the outer surfaces of the array substrate 100 and the counter substrate 200, that is, the optical transmission axes are arranged to be orthogonal to each other. That is, the optical transmission axis P1 of the polarizing plate 431
Is set to coincide with the alignment processing direction R, and the optical transmission axis P2 of the polarizing plate 441 is set to be orthogonal to the alignment processing direction R. The optical transmission axis P1 of the polarizing plate 431 and the polarizing plate 4
The optical transmission axis P2 of the reference numeral 41 is 4
The angle is set to 5 °.

Then, the pixel electrode 151 and the common electrode 204
In a state where no electric field is formed between the pixel electrode 151 and the common electrode 204, that is, when no voltage is applied between the pixel electrode 151 and the common electrode 204, as shown in FIG.
0 of the liquid crystal molecule 302 has a major axis direction of the array substrate 10.
0 and the alignment films 43 provided on the counter substrate 200, respectively.
1 and 441 are oriented parallel to the orientation processing directions.

At this time, the light beam of the optical transmission axis P1 that has passed through the polarizing plate 431 is transmitted to the optical transmission axis P2 orthogonal to P1.
Cannot be transmitted through the polarizing plate 441 having the transmittance, and the transmittance becomes minimum.

Then, the pixel electrode 151 and the common electrode 204
And the state where an electric field is formed between the pixel electrodes 15
In the on state in which a predetermined voltage is applied to each of the first and common electrodes 204, the liquid crystal molecules 302 are displaced such that the major axis direction is along the electric field direction E, as shown in FIG. That is, the liquid crystal molecules 302 are
And it rotates by a predetermined angle in a predetermined direction in a plane parallel to the counter substrate 200. This rotation angle depends on the strength of the electric field.

At this time, the light beam that has passed through the polarizing plate 431 generates a component parallel to the optical transmission axis P2 mainly using the birefringence effect of the liquid crystal molecules, and can pass through the polarizing plate 441. The transmittance is maximum.

Next, in the ON state, the array substrate 10
The pixel electrode 151A and the common electrode 204 provided on the 0 side
The voltage applied to A and the voltage applied to the pixel electrode 151B and the common electrode 204B provided on the counter substrate 200 side will be described more specifically.

First, the first example will be described. That is, in the ON state, for example, a voltage of 5 V is applied to the pixel electrode 151A on the array substrate 100 side via the TFT 121A, and a voltage of 1 V is applied to the common electrode 204A. Also, the pixel electrode 151B on the counter substrate 200 side
Similarly, a voltage of, for example, 5 V is applied via the TFT 121B, and a voltage of 1 V is applied to the common electrode 204B.

At this time, the TFT 121 on the opposite substrate 200 side
B is controlled in conjunction with the TFT 121A on the array substrate 100 side, so that the pixel electrode 1 on the counter substrate 200 side is controlled.
A voltage of the same level as that of the pixel electrode 151A on the array substrate 100 side, for example, a voltage of 5V is supplied to 51B. Further, the same level voltage, for example, a voltage of 1 V is supplied to the common electrode 121B on the counter substrate 200 side in conjunction with the common electrode 121A on the array substrate 100 side.

By applying such voltages to the pixel electrode 151A and the common electrode 121A on the array substrate 100 side and the pixel electrode 151B and the common electrode 121B on the counter substrate 200 side, respectively, an electric field as shown in FIG. 5 is formed. Is done.

That is, as shown in FIG. 5, a potential difference occurs between the pixel electrode 151A and the common electrode 204A on the array substrate 100 side, and
A substantially parallel horizontal electric field is formed on the array substrate 100 toward 04A. Similarly, a potential difference occurs between the pixel electrode 151B and the common electrode 204B also on the counter substrate 200 side,
A substantially parallel horizontal electric field is formed on the counter substrate 200 from the pixel electrode 151B toward the common electrode 204B.

By applying the above-described voltage to each electrode having such a structure, a strong horizontal electric field can be formed in almost the entire region between the array substrate 100 and the counter substrate 200. A strong horizontal electric field can be formed near the substrate 100 and the counter substrate 200.

At this time, since a voltage of the same level of 5 V is applied to the pixel electrode 151A on the array substrate 100 side and the pixel electrode 151B on the counter substrate 200 side opposed to the pixel electrode 151A, Pixel electrode 151A
No electric field is formed between the pixel electrode 151B and the pixel electrode 151B.
That is, it is possible to suppress the formation of a vertical electric field perpendicular to the substrate in the vicinity of the pixel electrodes 151A and 151B.

Further, the common electrode 20 on the array substrate 100 side
4A and the common electrode 204B on the side of the counter substrate 200 disposed opposite to the common electrode 204A,
Since a voltage of V is applied, no electric field is formed between the common electrode 204A and the common electrode 204B. That is, it is possible to suppress the formation of a vertical electric field perpendicular to the substrate near the common electrodes 204A and 204B.

In the above-described lateral electric field control type liquid crystal display device, in the ON state, the liquid crystal molecules contained in the liquid crystal layer 300 are caused to be dispersed by the array substrate 1 by such a strong lateral electric field.
The liquid crystal molecules are driven by being rotated by a predetermined angle in a plane substantially parallel to the counter substrate 200 and the counter substrate 200 so that the long axis direction of the liquid crystal molecules is substantially parallel to the electric field direction. At this time, since a strong transverse electric field is formed not only in the vicinity of the array substrate 100 and the counter substrate 200 but also in almost the entire area of the liquid crystal layer 300, it is possible to control the alignment state of the liquid crystal molecules over almost the entire area. Becomes

In addition, since the generation of a vertical electric field irrelevant to the driving of liquid crystal molecules can be suppressed in the vicinity of the electrode, the generation of an abnormal liquid crystal region such as a region where the horizontal electric field is weak or a region where the vertical electric field is formed is suppressed. However, the problem that the liquid crystal molecules cannot be sufficiently driven and the problem that the alignment state of the liquid crystal molecules is disturbed can be solved.

Further, in such a lateral electric field control type liquid crystal display device, the pixel electrode 151 is also provided on the counter substrate 200 side.
By supplying a predetermined level of voltage by arranging a conductive material such as B and the counter electrode 204B, a floating state is prevented, and charging due to accumulation of charges on the counter substrate 200 is prevented.

For this reason, it is possible to prevent the formation of an electric field irrelevant to the driving of the liquid crystal molecules and to suppress the disturbance of the alignment of the liquid crystal molecules. Therefore, the occurrence of display defects is prevented,
A liquid crystal display device with high display quality can be provided.

Next, a second example will be described. That is, in the ON state, for example, a voltage of 5 V is applied to the pixel electrode 151A on the array substrate 100 side via the TFT 121A, and a voltage of 1 V is applied to the common electrode 204A. Also, the pixel electrode 151B on the counter substrate 200 side
The same level voltage, for example, a voltage of 1 V, is applied to the common electrode 204B via voltage supply means such as the TFT 121B.

At this time, the voltage supply means on the counter substrate 200 side applies a voltage controlled independently of the TFT 121A on the array substrate 100 side to the pixel electrode 151B and the common electrode 204.
B respectively.

By applying such voltages to the pixel electrode 151A and the common electrode 121A on the array substrate 100 side and the pixel electrode 151B and the common electrode 121B on the counter substrate 200 side, an electric field as shown in FIG. 6 is formed. Is done.

That is, as shown in FIG. 6, on the array substrate 100 side, a potential difference is generated between the pixel electrode 151A and the common electrode 204A, and the common electrode 2
A substantially parallel horizontal electric field is formed on the array substrate 100 toward 04A. On the other hand, on the counter substrate 200 side, the pixel electrode 15
Since the same level of voltage is supplied to 1B and the common electrode 204B, a potential difference does not occur, and a substantially parallel horizontal electric field is not formed on the counter substrate 200.

In the lateral electric field control type liquid crystal display device as described above, in the ON state, a conductive material such as the pixel electrode 151B and the counter electrode 204B is also disposed on the counter substrate 200 side to supply a predetermined level of voltage. In addition, the floating state is prevented, and charging due to accumulation of charges on the counter substrate 200 is prevented.

For this reason, it is possible to prevent the formation of an electric field irrelevant to the driving of the liquid crystal molecules and to suppress the disturbance of the alignment of the liquid crystal molecules. Therefore, the occurrence of display defects is prevented,
A liquid crystal display device with high display quality can be provided.

Next, a third example will be described. That is, in the ON state, for example, a voltage of 5 V is applied to the pixel electrode 151A on the array substrate 100 side via the TFT 121A, and a voltage of 1 V is applied to the common electrode 204A. Also, the pixel electrode 151B on the counter substrate 200 side
And the common electrode 204B has the same level of voltage through a voltage supply means such as a TFT and the pixel electrode 15B.
A voltage at a substantially intermediate level between the highest voltage and the lowest voltage supplied to 1A and the common electrode 204A, for example, a voltage of 3V is applied.

At this time, the voltage supply means on the counter substrate 200 side applies a voltage controlled independently of the TFT 121A on the array substrate 100 to the pixel electrode 151B and the common electrode 204.
B respectively.

By applying such voltages to the pixel electrode 151A and the common electrode 121A on the array substrate 100 side and the pixel electrode 151B and the common electrode 121B on the counter substrate 200 side, an electric field as shown in FIG. 7 is formed. Is done.

That is, as shown in FIG. 7, on the array substrate 100 side, a potential difference occurs between the pixel electrode 151A and the common electrode 204A, and the common electrode 2
A substantially parallel horizontal electric field is formed on the array substrate 100 toward 04A. On the other hand, on the counter substrate 200 side, the pixel electrode 15
Since the same level voltage is supplied to 1B and the common electrode 204B, no potential difference occurs. However, the counter substrate 2
The 00-side pixel electrode 151B and the common electrode 204B have
Pixel electrode 151A on array substrate 100 side and common electrode 2
Since a voltage at an intermediate level between the maximum voltage and the minimum voltage is supplied to the pixel electrode 151B on the counter substrate 200 side and the common electrode 20 on the array substrate 100 side.
4A, and the common electrode 204B on the counter substrate 200 side and the pixel electrode 15 on the array substrate 100 side.
1A is generated. Therefore, the pixel electrode 15
An oblique electric field from 1B to the common electrode 204A and an oblique electric field from the pixel electrode 151A to the common electrode 204B are formed.

By the interaction of these oblique electric fields, an electric field having a horizontal component substantially parallel to the array substrate 100 and the counter substrate 200 is formed, and a strong horizontal electric field can be formed.

In the lateral electric field control type liquid crystal display device as described above, in the ON state, the liquid crystal molecules contained in the liquid crystal layer 300 are caused to be displaced by the strong lateral electric field.
The liquid crystal molecules are driven by being rotated by a predetermined angle in a plane substantially parallel to the counter substrate 200 and the counter substrate 200 so that the long axis direction of the liquid crystal molecules is substantially parallel to the electric field direction. At this time, since a strong transverse electric field is formed not only in the vicinity of the array substrate 100 and the counter substrate 200 but also in almost the entire area of the liquid crystal layer 300, it is possible to control the alignment state of the liquid crystal molecules over almost the entire area. Becomes

Further, in such a lateral electric field control type liquid crystal display device, the pixel electrode 151 is also provided on the counter substrate 200 side.
By supplying a predetermined level of voltage by arranging a conductive material such as B and the counter electrode 204B, a floating state is prevented, and charging due to accumulation of charges on the counter substrate 200 is prevented.

For this reason, it is possible to prevent the formation of an electric field irrelevant to the driving of the liquid crystal molecules and to suppress the disorder of the alignment of the liquid crystal molecules. Therefore, the occurrence of display defects is prevented,
A liquid crystal display device with high display quality can be provided.

The above-described embodiment is mainly used for monochrome display. In order to achieve color display, it is necessary to arrange a colored layer, that is, a color filter, on one of the array substrate and the counter substrate. A horizontal electric field control type liquid crystal display device for achieving color display is, for example, a so-called color filter-on-array structure in which a color filter is provided on the array substrate side and a pixel electrode and a common electrode are arranged on the color filter. The COA structure applies. Note that the same components as those of the liquid crystal display device according to the embodiment already described with reference to FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description is omitted.

That is, as shown in FIGS. 8 and 9, the display area 102 of the array substrate 100 is
1 signal lines 103 arranged orthogonally to each other
A, a scanning line 111A, and a TFT 121A. The scanning lines 111A are provided directly on the glass substrate 101, and the signal lines 103A are provided on an insulating film 113A formed on the glass substrate 101.

The TFT 121A uses the scanning line 111A itself as a gate electrode, via a semiconductor layer 115A disposed via a gate insulating film 113A, a channel protective film 117A laminated on the semiconductor layer 115A, and a low-resistance semiconductor film 119A. It has a source electrode 131A and a drain electrode 132A electrically connected to the semiconductor film 115A.

The array substrate 100 further includes a coloring layer, ie, a color filter C, disposed for each pixel region on the insulating film 133, and a light-shielding film, ie, a black matrix BM, disposed on the TFT 121A and the wiring. doing. As the color filters C, a red color filter CR containing a red pigment, a green color filter CG containing a green pigment, and a blue color filter CB containing a blue pigment are arranged for each pixel region.

On the color filter C in the pixel area, a common electrode 204A is arranged.
4, a pixel electrode 151A is arranged. The common electrode 204A has a through hole TH1 as shown in FIG.
Are electrically connected to the scanning lines arranged on the glass substrate 101 via the. In addition, the pixel electrode 151A is
And as shown in FIG. 9, T through the through hole TH2.
It is electrically connected to the source electrode 131A of the FT 121A.

The end of the pixel electrode 151A forms a first auxiliary capacitance electrode portion 273A for forming the auxiliary capacitance Cs. The common electrode 204A includes first and second electrode portions 205A and 205A wired substantially parallel to the pixel electrode 151A.
06A, the first auxiliary capacitance electrode portion 273A, and the insulating film 134
And the second storage capacitor electrode portion 207A overlapping with the second storage capacitor electrode portion 207A.

The surface of the array substrate 100 is covered with an alignment film 141A for aligning liquid crystal molecules contained in the liquid crystal composition 300 interposed between the array substrate 100 and the counter substrate 200.

The counter substrate 200 is configured in the same manner as in the above-described embodiment, and a detailed description will be omitted. The liquid crystal display panel 10 is formed by bonding the above-described array substrate 100 and the opposing substrate 200 at a predetermined interval with the sealant 106.

In the lateral electric field control type liquid crystal display device to which such a COA structure is applied, the same effect can be obtained by applying the same voltage to each electrode in the on state as in the above-described embodiment. , Color display can be realized.

Next, an embodiment of a liquid crystal display device capable of improving the response speed of liquid crystal molecules when transitioning from the on state to the off state will be described. As described above with reference to FIGS. 4A and 4B, the liquid crystal molecules 302 included in the liquid crystal composition are in the off state, and the alignment films 141A and 141A provided on the array substrate 100 and the counter substrate 200, respectively. 1
The alignment is performed in the first direction D1 parallel to the alignment processing direction R only by the alignment control force by 41B.

The pixel electrode 151 and the common electrode 20
When a predetermined voltage is applied to each of the liquid crystal molecules 4, the liquid crystal molecules 302 shift from the off state to the on state. That is, the liquid crystal molecules 302 rotate clockwise in the plane of the drawing due to the electric field formed between the pixel electrode 151 and the common electrode 204, and the second direction parallel to the electric field direction E from the first direction D1. Displaced in the direction D2.

The liquid crystal molecules 302 are
When the application of the voltage to 51 and the common electrode 204 is stopped, the state changes from the on state to the off state. At this time,
The liquid crystal molecules 302 rotate counterclockwise in the plane of the drawing due to the alignment regulating force of the alignment films 141A and 141B, and are again displaced from the second direction D2 to the first direction D1.

As described above, the response speed of the liquid crystal molecules 302 at the time of transition from the on state to the off state depends only on the alignment regulating force of the alignment film. For this reason, it has been difficult to improve the response speed of the liquid crystal molecules 302 when transitioning from the on state to the off state.

Therefore, in the horizontal electric field control type liquid crystal display device according to this embodiment, a displacement force for displacing the liquid crystal molecules 302 from the second direction D2 to the first direction D1 is applied to the liquid crystal composition. Chiral substances have been added.

That is, the chiral substance gives the liquid crystal molecules 302 a rotational direction that is opposite to the clockwise direction, ie, a clockwise direction, that is, a counterclockwise displacement force when transitioning from the off state to the on state. Examples of such a chiral substance include 2-octyl 4- (4-hexyloxybenzoyloxy) benzoate (E. Merck: S-B11).

Therefore, when the liquid crystal molecules 302 shift from the on-state to the off-state, the liquid crystal molecules 302 rapidly rotate from the second direction D2 to the first direction D1 due to the displacement force applied from the chiral substance. This makes it possible to improve the response speed of the liquid crystal molecules 302 when transitioning from the on state to the off state, and to display a higher-definition moving image or the like.

As described above, according to the liquid crystal display device of the present invention, the pixel electrode as the first electrode and the common electrode as the second electrode are provided on the array substrate, and the third electrode is provided on the opposite substrate. And a common electrode as a fourth electrode. A voltage controlled independently of a voltage applied to the first electrode and the second electrode is supplied to the third electrode and the fourth electrode by a switching element, that is, a TFT as a voltage supply unit.

As described above, by providing the third and fourth electrodes on the counter substrate side, it is possible to prevent charges from being accumulated and charged on the counter substrate. In addition, at least between the first electrode and the second electrode and between the third electrode and the fourth electrode, a horizontal electric field substantially parallel to the substrate can be formed. In the vicinity, a strong horizontal electric field can be formed.

As a result, problems such as formation of a region where a horizontal electric field is weak near the counter substrate and formation of a vertical electric field near the electrodes are eliminated, and generation of an abnormal liquid crystal region can be suppressed. Therefore, it is possible to provide a liquid crystal display device with improved display quality by preventing charging of the opposing substrate and suppressing occurrence of a liquid crystal abnormal region.

According to the liquid crystal display device of the present invention,
The liquid crystal composition includes a liquid crystal molecule that is displaced in a predetermined direction in a state where an electric field is formed by a voltage applied to the first electrode and the second electrode, and a displacement that displaces the liquid crystal molecule in a direction opposite to the predetermined direction. A chiral substance that imparts power. Thus, when the electric field shifts from the on state to the off state, the liquid crystal molecules can be quickly displaced to the off state by the displacement force of the chiral substance. Therefore, it is possible to provide a liquid crystal display device having improved response speed of liquid crystal molecules.

[0102]

As described above, according to the present invention, it is possible to provide a liquid crystal display device in which the charging of the opposing substrate is prevented, the abnormal region of the liquid crystal is suppressed, and the display quality is improved.

Further, according to the present invention, it is possible to provide a liquid crystal display device in which the response speed of liquid crystal molecules, in particular, the response speed of liquid crystal molecules when shifting from an on state to an off state is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a lateral electric field control type liquid crystal display device according to an embodiment of the liquid crystal display device of the present invention.

FIG. 2 is a plan view schematically showing an array substrate and a counter substrate applied to the liquid crystal display device shown in FIG.

FIG. 3 shows the array substrate and the counter substrate of FIG.
It is sectional drawing at the time of fracture | rupture by A line.

4A is a diagram for explaining an off state of the in-plane switching mode liquid crystal display device of the present invention, and FIG. 4B is a diagram for explaining an on state. It is.

FIG. 5 is a diagram for explaining a state of an electric field formed by a voltage applied to the liquid crystal display device of the present invention.

FIG. 6 is a diagram for explaining a state of an electric field formed by a voltage applied to the liquid crystal display device of the present invention.

FIG. 7 is a diagram for explaining a state of an electric field formed by a voltage applied to the liquid crystal display device of the present invention.

FIG. 8 is a plan view schematically showing an array substrate having a COA structure applicable to the liquid crystal display device of the present invention.

FIG. 9 is a cross-sectional view of the array substrate having the COA structure shown in FIG. 8 taken along the line AA.

[Explanation of symbols]

 Reference Signs List 10 liquid crystal display device 100 array substrate 103 (A, B) signal line 111 (A, B) scanning line 121 (A, B) switching element (TFT) 141 (A, B) alignment film 151 ( A, B) Pixel electrode 200 Counter substrate 204 Common electrode 300 Liquid crystal composition 302 Liquid crystal molecules

Claims (7)

[Claims] 1. A liquid crystal display device comprising: an array substrate; a counter substrate disposed to face the array substrate; and a liquid crystal composition sandwiched between the array substrate and the counter substrate. A first electrode disposed on one main surface of the substrate; and a second electrode disposed at a predetermined distance from the first electrode.
An electrode, and a switching element for controlling a voltage applied to the first electrode, wherein the counter substrate is disposed on one main surface of the substrate and faces a third electrode facing the first electrode; A fourth electrode arranged at a predetermined distance from the third electrode and facing the second electrode; applying a fourth electrode to the third electrode and the fourth electrode; applying a fourth electrode to the first electrode and the second electrode; And a voltage supply means for supplying a voltage controlled independently of the voltage to be supplied. 2. The voltage supply means supplies a voltage of the same level as the voltage applied to the first electrode and the second electrode to the third electrode and the fourth electrode, respectively. The liquid crystal display device according to claim 1. 3. The liquid crystal display device according to claim 1, wherein said voltage supply means supplies a voltage of the same level to said third and fourth electrodes. 4. The voltage supply means supplies a voltage at an intermediate level between a maximum voltage and a minimum voltage applied to the first and second electrodes to the third and fourth electrodes. The liquid crystal display device according to claim 3, wherein: 5. A liquid crystal display device comprising: an array substrate; a counter substrate disposed to face the array substrate; and a liquid crystal composition sandwiched between the array substrate and the counter substrate. A first electrode disposed on one main surface of the substrate; and a second electrode disposed at a predetermined distance from the first electrode.
An electrode; and a switching element for controlling a voltage applied to the first electrode. The liquid crystal composition is arranged in a predetermined direction in a state where an electric field is formed by the voltage applied to the first electrode and the second electrode. A liquid crystal display device comprising: a liquid crystal molecule that displaces a liquid crystal molecule; and a chiral substance that applies a displacement force to displace the liquid crystal molecule in a direction opposite to the predetermined direction. 6. The liquid crystal composition according to claim 1, wherein the liquid crystal composition comprises the first electrode to the fourth electrode.
Liquid crystal molecules that are displaced in a predetermined direction in a state where an electric field is formed by a voltage applied to the electrode, and a chiral substance that applies a displacement force to displace the liquid crystal molecules in a direction opposite to the predetermined direction. The liquid crystal display device according to claim 1, wherein: 7. An alignment means for aligning a major axis of said liquid crystal molecules in a first direction, and an electric field forming means for forming an electric field for twisting a major axis of said liquid crystal molecules from said first direction to a second direction. ,
7. The liquid crystal display device according to claim 5, wherein the chiral substance imparts a force to twist the major axis of the liquid crystal molecules from the second direction to the first direction to the liquid crystal composition. 8. .