JP2010175886A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an FFS mode liquid crystal display device with which decrease in transmittance can be suppressed even if transparent conductive electrode for preventing static electricity is formed on the rear side of a color filter substrate. <P>SOLUTION: The liquid crystal display device 10A has a first substrate 16 and a second substrate 29 oppositely arranged with a liquid crystal layer LC therebetween. The first substrate 16 includes: an upper electrode 26A which has a plurality of slit openings 27A formed for each of sub-pixel regions 12R, 12G, 12B; and a lower electrode 23 which is formed on the first substrate side via the upper electrode 26A and an insulation layer 25. The second substrate 29 includes a transparent conductive electrode 34 for preventing static electricity on the liquid crystal layer LC side. A condition L≥W is satisfied, where the width of the slit openings 27A of the upper electrode 26A is W, and the width of the linear upper electrode 26A between the slit openings 27A is L. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an FFS (Fringe Field Switching) mode liquid crystal display device, and more particularly to an FFS mode liquid crystal display device that can suppress a decrease in transmittance even when a transparent conductive electrode for preventing static electricity is formed on the inner surface side of a color filter substrate. The present invention relates to a liquid crystal display device.

A liquid crystal display device has characteristics of light weight, thinness, and low power consumption as compared with a CRT (cathode ray tube), and thus is used in many electronic devices for display. The liquid crystal display device displays an image by changing the direction of liquid crystal molecules aligned in a predetermined direction by an electric field and changing the amount of light transmitted through the liquid crystal layer. This includes a reflective type in which external light is incident on the liquid crystal layer, reflected by the reflector, then transmitted again through the liquid crystal layer, and a transmissive type in which incident light from the backlight device is transmitted through the liquid crystal layer. And a transflective type having both properties.

As a method for applying an electric field to a liquid crystal layer of a liquid crystal display device, there are a vertical electric field method and a horizontal electric field method. A vertical electric field type liquid crystal display device applies a substantially vertical electric field to liquid crystal molecules by a pair of electrodes arranged with a liquid crystal layer interposed therebetween. As the vertical electric field type liquid crystal display device, a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an MVA (Multi-domain Vertical Alignment) mode, and the like are known. A horizontal electric field type liquid crystal display device has a pair of electrodes insulated from each other on one inner surface side of a pair of substrates arranged with a liquid crystal layer interposed therebetween, and an electric field in a substantially horizontal direction is used as liquid crystal molecules. In contrast, it is applied. As this lateral electric field type liquid crystal display device, there are known an IPS (In-Plane Switching) mode in which a pair of electrodes do not overlap in a plan view and an FFS mode in which they overlap (see Patent Document 1 below). . A horizontal electric field type liquid crystal display device has an effect that a wide viewing angle can be obtained.

In addition, a common electrode is formed on the transparent substrate on the display surface side in the vertical electric field type liquid crystal display device, but this common electrode is formed on the transparent substrate on the display surface side in the FFS mode liquid crystal display device. Therefore, the alignment of liquid crystal molecules may be disturbed due to static electricity from a human finger or the like. Therefore, in order to prevent image disturbance due to static electricity in the FFS mode liquid crystal display device,
Patent Document 2 listed below has a transparent conductive electrode for preventing static electricity formed on the outer surface (display surface side) of the color filter substrate. Patent Document 3 listed below describes the inner surface (liquid crystal layer side) of the color filter substrate. Each of which is formed with a transparent conductive electrode for preventing static electricity is disclosed.

JP 2001-056476 A Japanese Patent Laid-Open No. 2005-043901 JP 2008-129405 A

Transparent conductive electrodes for preventing static electricity are ITO (Indium Thin Oxide) or IZO (Indiu
m Zinc Oxide), etc., and is usually formed by sputtering. Therefore, in order to form a transparent conductive electrode for preventing static electricity on the outer surface of the color filter substrate, it is necessary to dispose a liquid crystal display device in which liquid crystal is sealed in a vacuum atmosphere. Therefore, the FFS mode liquid crystal display device disclosed in Patent Document 2 has a problem in that yield reduction such as panel cracking occurs when a transparent conductive electrode for preventing static electricity is formed. In addition, a polarizing plate is attached to the outer surface of the color filter substrate. Depending on the material for forming this polarizing plate, the transparent conductive electrode for preventing static electricity may be melted. It may not be effective.

Moreover, when a transparent conductive electrode for preventing static electricity is formed on the outer surface of the color filter substrate, it is necessary to apply a conductive paste to electrically connect the transparent conductive electrode to a specific external potential. The problem arises that the frame area becomes large due to the necessity of forming the paste application part. In addition, a process for checking electrical continuity between the external potential and the transparent conductive electrode for preventing static electricity is required, and there are problems of increased costs due to increased processes and reduced manufacturing yield.

Therefore, it is desirable to form the transparent conductive electrode for preventing static electricity on the inner surface side of the color filter substrate as disclosed in Patent Document 3 above. However,
According to the present inventors' research, in the conventional FFS mode liquid crystal display device, when the transparent conductive electrode for preventing static electricity is formed on the inner surface side of the color filter substrate, the slit of the upper electrode formed on the array substrate side It has been found that there is a problem that the transmittance decreases due to an increase in the reverse twist domain at the end of the aperture and an increase in the width of the in-plane luminance distribution.

The present invention has been made to solve such problems of the prior art, and is formed on the inner surface of the color filter substrate and on the array substrate side with a transparent conductive electrode for preventing static electricity. An object of the present invention is to provide an FFS mode liquid crystal display device in which a reduction in transmittance is suppressed by optimizing the shape of the slit-like opening of the upper electrode.

In order to achieve the above object, the liquid crystal display device of the present invention comprises:
A first substrate and a second substrate disposed opposite to each other with a liquid crystal layer interposed therebetween;
The first substrate includes
A plurality of signal lines and scanning lines formed in a matrix in a state of being insulated from each other, and an upper electrode having a plurality of slit-like openings formed for each sub-pixel region partitioned by the scanning lines and the signal lines; The lower electrode formed on the substrate side through the upper electrode and an insulating layer,
In the second substrate, a liquid crystal display device comprising a transparent conductive electrode for preventing static electricity on the liquid crystal layer side,
When the width of the slit-shaped opening of the upper electrode is W, and the width of the linear upper electrode portion located between the slit-shaped openings is L,
L ≧ W
It satisfies the conditions of

In the liquid crystal display device of the present invention, the first substrate has an upper electrode having a plurality of slit-like openings formed for each sub-pixel region partitioned by the scanning lines and the signal lines, and the upper electrode and the insulating layer interposed therebetween. And a lower electrode formed on the substrate side, so that an FFS mode liquid crystal display device is obtained. In addition, in the conventional FFS mode liquid crystal display device, the width of the slit-shaped opening of the upper electrode is set to W,
When the width of the linear upper electrode portion located between the slit-shaped openings is L, L <W. Therefore, when a transparent conductive electrode for preventing static electricity is formed on the liquid crystal layer side of the second substrate, the reverse twist domain is increased at the end of the slit-like opening and the nonuniformity of the luminance portion distribution is increased in the display surface. Therefore, the transmittance was reduced.

This phenomenon occurs because the electric field distribution between the upper electrode and the lower electrode changes due to the electric field formed between the transparent conductive electrode for preventing static electricity and the upper electrode, and the upper electrode and the lower electrode This is because the amount of twist of liquid crystal molecules at the end of the slit-like opening and the upper surface of the upper electrode changes between the electrodes.

On the other hand, according to the liquid crystal display device of the present invention, since the relationship between W and L is such that L ≧ W, the slits can be clearly confirmed from the measurement results of the following examples and comparative examples. The reverse twist domain does not increase at the end of the aperture, and the nonuniformity of the luminance portion distribution does not increase in the display surface, so that a liquid crystal display device in which the decrease in transmittance is suppressed can be obtained. Moreover, in the liquid crystal display device of the present invention, since the transparent conductive electrode for preventing static electricity is formed on the inner surface side of the second substrate, compared with the case where the transparent conductive electrode for preventing static electricity is formed on the outer surface of the second substrate. , Low cost and short process can be realized. In the liquid crystal display device of the present invention, the color filter layer may be formed as necessary, and is not necessarily required.

In the liquid crystal display device of the present invention, it is preferable that the slit-like openings are connected to each other between the plurality of sub-pixels forming a unit pixel.

In the FFS mode liquid crystal display device, when the slit-shaped openings formed in the upper electrode are connected to each other among the plurality of sub-pixels forming the unit pixel, the number of ends of the slit-shaped openings in the unit pixel is reduced. Thus, the occurrence of reverse twist domains is reduced. For this reason, according to the liquid crystal display device of the present invention, the relationship between W and L is such that L ≧ W and the number of ends of the slit-like openings in the unit pixel is reduced. Combined with the effect, a reverse twist domain is less likely to occur, and a decrease in transmittance is suppressed.

In the liquid crystal display device of the present invention, the slit openings may be connected to each other between the plurality of sub-pixels forming a plurality of unit pixels.

In the FFS mode liquid crystal display device, when the slit-shaped openings formed in the upper electrode are connected to each other between the plurality of sub-pixels forming the plurality of unit pixels, the end portions of the slit-shaped openings in the plurality of unit pixels The number of will decrease more. Therefore, according to the liquid crystal display device of the present invention, the effect of setting the relationship between W and L to be L ≧ W and the number of ends of the slit-like openings in the plurality of unit pixels are reduced. Combined with the effect of this, reverse twist domains are less likely to occur, and a decrease in transmittance is suppressed.

In the liquid crystal display device of the present invention, it is assumed that the static-preventing transparent conductive electrode is formed in a region excluding an end of the slit-like opening formed in the upper electrode in plan view. Also good.

In the FFS mode liquid crystal display device, when a transparent conductive electrode for preventing static electricity of the liquid crystal display device is formed on the inner surface side of the second substrate, a reverse twist domain is generated at the end of the slit-shaped opening formed in the upper electrode. It becomes easy to do. On the other hand, in the liquid crystal display device of the present invention, since the transparent conductive electrode for preventing static electricity is not formed at the end of the slit-like opening formed in the upper electrode in plan view, the reverse twist domain hardly occurs. Therefore, a liquid crystal display device having the above effects can be obtained.

In the liquid crystal display device of the present invention, the static-preventing transparent conductive electrode is electrically connected to one selected from a ground potential, a common wiring, the upper electrode, and the lower electrode. Is preferred.

The transparent conductive electrode for preventing static electricity can provide a certain shielding effect even in a floating state. However, according to the liquid crystal display device of the present invention, the transparent conductive electrode for preventing static electricity is connected to one selected from the ground potential, the common wiring, the upper electrode, and the lower electrode. Since the potential of the transparent conductive electrode is stabilized, the shielding effect is enhanced. Note that the ground potential (earth potential) is a potential at which any liquid crystal display device exists as a reference potential of a driver circuit for driving the liquid crystal display device.
The common wiring is a wiring in which any liquid crystal display device to which a voltage serving as a reference of a voltage applied to the pair of electrodes of the liquid crystal display device is applied exists.

Furthermore, when a transparent conductive electrode for preventing static electricity is formed on the outer surface (observer side) of the color filter substrate of the second substrate as in the prior art, this transparent conductive electrode is electrically connected to a specific external potential. In order to form a paste application portion for connection to the frame, the frame area becomes large, and an electrical continuity check step between the external potential and the transparent conductive electrode for preventing static electricity is required. On the other hand, according to the liquid crystal display device of the present invention, the transparent conductive electrode for preventing static electricity of the liquid crystal display device is formed on the inner surface side (liquid crystal layer side) of the second substrate, and the ground potential is formed inside the liquid crystal display device. Since it is connected to one selected from the common wiring, the upper electrode, and the lower electrode, it is not necessary to widen the frame area and the electrical conduction between the transparent conductive electrode for preventing static electricity is ensured. This improves the manufacturing yield.

It is a schematic plan view for 3 sub-pixels on the array substrate side of the embodiment. It is a schematic plan view for 3 sub pixels on the array substrate side of a comparative example. It is sectional drawing of the III-III line | wire of FIG. It is a figure which shows the luminance distribution of the liquid crystal display device of an Example, a comparative example, and a prior art example. It is a figure which shows the electric potential-transmittance curve of the liquid crystal display device of an Example, a comparative example, and a prior art example. 10 is a schematic plan view of three sub-pixels on the array substrate side in Modification 1. FIG. 10 is a schematic plan view of three sub-pixels on the array substrate side in Modification 2. FIG. FIG. 10 is a schematic plan view of three sub-pixels on the array substrate side, which are shown to overlap with a transparent conductive electrode for electrostatic protection in Modification 3. FIG. 10 is a schematic plan view of three sub-pixels on the array substrate side, which is shown superimposed on a transparent conductive electrode for electrostatic protection in Modification 4.

Hereinafter, the best mode for carrying out the present invention will be described by way of examples and comparative examples with reference to the drawings. However, the following examples are intended to limit the present invention to those described herein. However, the present invention can be equally applied to various modifications without departing from the technical idea shown in the claims. In each drawing used for the description in this specification, each layer and each member are displayed in different scales so that each layer and each member can be recognized on the drawing. However, it is not necessarily displayed in proportion to the actual dimensions.

FIG. 1 is a schematic plan view of three sub-pixels on the array substrate side of the embodiment. FIG. 2 is a schematic plan view of three sub-pixels on the array substrate side of the comparative example. 3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a diagram showing the luminance distribution of the liquid crystal display devices of the example, the comparative example, and the conventional example. FIG. 5 is a diagram showing potential-transmittance curves of liquid crystal display devices of examples, comparative examples, and conventional examples. FIG. 6 is a schematic plan view of three sub-pixels on the array substrate side in the first modification. FIG. 7 is a schematic plan view of three sub-pixels on the array substrate side in the second modification. FIG. 8 is a schematic plan view corresponding to three sub-pixels on the array substrate side, which is superimposed on the transparent conductive electrode for electrostatic protection in Modification 3. FIG. 9 is a schematic plan view corresponding to three sub-pixels on the array substrate side, which are superimposed on the transparent conductive electrode for electrostatic protection in Modification 4.

[Example]
The liquid crystal display device 10A of the embodiment operates in the FFS mode, and the configuration of the main part of the liquid crystal display device 10A will be described with reference to FIGS. As shown in FIG. 1, the unit pixel 11 of the liquid crystal display device 10A includes a red sub-pixel 12R and a green sub-pixel 12 which are the three primary colors of light.
It is composed of G and blue sub-pixels 12B, and the color of the unit pixel 11 is determined by the color mixture of these three sub-pixels.

As shown in FIG. 3, the first polarizing plate 13 is attached to the back side of the liquid crystal display device 10 </ b> A, the second polarizing plate 14 is attached to the display surface side, and the liquid crystal is applied to the back side of the first polarizing plate 13. A backlight device (not shown) for irradiating the display device 10A with light is disposed.

In the liquid crystal display device 10A, the liquid crystal layer LC is sandwiched between the array substrate AR and the color filter substrate CF. The array substrate AR is based on a first transparent substrate 16 made of transparent insulating glass, quartz, plastic or the like. On the first transparent substrate 16, scanning lines 17 made of a metal such as aluminum or molybdenum are formed on the side facing the liquid crystal LC so as to extend in the row direction (lateral direction) in FIG. 1. A part of the scanning line 17 is a gate electrode G.

A transparent gate insulating film 18 made of silicon nitride, silicon oxide or the like is laminated so as to cover the scanning line 17 and the gate electrode G. A semiconductor layer 19 made of amorphous silicon, polycrystalline silicon, or the like is formed on the gate insulating film 18 that overlaps the gate electrode G in plan view. A plurality of signal lines 20 made of a metal such as aluminum or molybdenum are formed on the gate insulating film 18 so as to extend in the column direction (vertical direction) in FIG. These scan lines 1
7 and each of the regions partitioned by the signal line 20 form one subpixel. A source electrode S extends from the signal line 20, and the source electrode S is in partial contact with the surface of the semiconductor layer 19.

Further, a drain electrode D simultaneously formed of the same material as the signal line 20 and the source electrode S is provided on the gate insulating film 18, and the drain electrode D is disposed in the vicinity of the source electrode S and the semiconductor layer 19. Partially touching. Since one unit pixel is substantially square,
The equally divided sub-pixels 12R, 12G, and 12B are rectangular with the scanning line 17 side having a short side and the signal line 20 side having a long side. The gate electrode G, the gate insulating film 18, the semiconductor layer 19, the source electrode S, and the drain electrode D constitute a thin film transistor TFT serving as a switching element, and this TFT is formed in each of the sub-pixels 12R, 12G, and 12B.

Further, a transparent passivation film 21 made of, for example, silicon nitride or silicon oxide is laminated so as to cover the exposed portions of the signal line 20, the TFT, and the gate insulating film 18. Then, a planarizing resin layer 22 made of a transparent resin material such as a photoresist is laminated so as to cover the passivation film 21. A lower electrode 23 made of a transparent conductive material such as ITO or IZO is formed so as to cover the planarizing resin layer 22. A contact hole 24 that penetrates the planarizing resin layer 22 and the passivation film 21 and reaches the drain electrode D is formed, and the lower electrode 23 and the drain electrode D are electrically connected through the contact hole 24. . Therefore, here, the lower electrode 23 operates as a pixel electrode.

A transparent interelectrode insulating film 25 made of, for example, silicon nitride or silicon oxide is laminated so as to cover the lower electrode 23. Then, ITO or I is formed so as to cover the interelectrode insulating film 25.
An upper electrode 26A made of a transparent conductive material such as ZO is formed. Each sub-pixel 12R, 1
The upper electrodes 26A of 2G and 12B are integrally formed and operate as a common electrode. As shown in FIG. 1, the upper electrode 26A has a plurality of slit-shaped openings 27A. The slit-shaped opening 27A has a rectangular shape, and its longitudinal direction is inclined with respect to the extending direction of the scanning line 17 to the right by about 5 degrees, and the longitudinal direction is inclined to the right with about 5 degrees. Is formed. The two types of slit-shaped openings 27A in the central portion are connected to each other at one end so as to have a horizontal V shape. Thus, by providing the area | region where the extension direction of a slit differs, since VT (voltage-transmittance) characteristic becomes different in each side, the difference of the color by a viewing angle can be reduced.

In the liquid crystal display device 10A of this embodiment, the relationship between the width W of the slit-shaped opening 27A and the width L of the upper electrode 26A portion between the slit-shaped openings 27A satisfies L ≧ W. An alignment film 28 made of, for example, polyimide is laminated so as to cover the upper electrode 26A and the slit-shaped opening 27A. The alignment film 28 is subjected to a liquid crystal direction alignment process (rubbing process) in parallel with the extending direction of the signal line 20.

The color filter substrate CF is based on a second transparent substrate 29 made of transparent insulating glass, quartz, plastic, or the like. The second transparent substrate 29 is formed with a light shielding layer 30 and a color filter layer 31 that transmits light of different colors (for example, R, G, B) for each subpixel. The light shielding layer 30 is formed so as to overlap the scanning line 17, the signal line 20, the TFT, and the drain electrode D in a plan view. An area where the light shielding layer 30 of the sub-pixels 12R, 12G, and 12B is not formed is an effective display area, and a color filter layer 31 is formed there.

An overcoat layer 32 made of a transparent resin material such as a photoresist is laminated so as to cover the light shielding layer 30 and the color filter layer 31. The overcoat layer 32 is provided to flatten the steps due to the color filter layers 31 of different colors, and to block impurities flowing out from the light shielding layer 30 and the color filter layer 31 from entering the liquid crystal layer LC. Is. An alignment film 33 made of polyimide, for example, is formed so as to cover the overcoat layer 32. The alignment film 33 includes an alignment film 2 formed on the array substrate AR.
The liquid crystal direction alignment treatment in the direction opposite to that in FIG. Further, in the liquid crystal display device 10A of the embodiment, the second transparent substrate 29, the light shielding layer 30, and the color filter layer 3 of the color filter substrate CF are used.
1, a transparent conductive electrode 34 made of ITO or IZO for preventing static electricity is formed.

The array substrate AR and the color filter substrate CF thus formed are opposed to each other, a sealing material (not shown) is provided around both substrates, and the substrates are bonded together, and a liquid crystal is filled between the substrates. Thus, the liquid crystal display device 10A according to the first embodiment is obtained. A spacer (not shown) for holding the liquid crystal layer LC at a predetermined thickness is formed on the color filter substrate CF.

In addition, when the array substrate AR and the color filter substrate CF are bonded together, the transparent conductive electrode 34 for preventing static electricity is a frame region (not shown) in the periphery of the liquid crystal display device 10A.
Thus, it is electrically connected to one selected from the ground potential, the common wiring, the upper electrode, and the lower electrode through a conduction means between the two substrates, for example, a transfer electrode. Note that the ground potential is a potential that exists in any liquid crystal display device as a reference potential of a driver circuit for driving the liquid crystal display device, and the common wiring is applied to a pair of electrodes of the liquid crystal display device. This is a wiring in which any liquid crystal display device to which a voltage serving as a voltage reference is applied, and a specific configuration thereof is not illustrated.

With the above configuration, when the TFT is turned on and a voltage is applied between the lower electrode 23 and the upper electrode 26A, an electric field is generated between the electrodes 23 and 26A, and the alignment of the liquid crystal molecules in the liquid crystal layer LC changes. To do. As a result, the light transmittance of the liquid crystal layer LC changes and an image is displayed. The luminance distribution of the IVa-IVa portion of FIG. 1 of the liquid crystal display device 10A of this embodiment is shown by the curve a in FIG.
The relationship between the voltage applied between the lower electrode 23 and the upper electrode 26A of the liquid crystal display device 10A of the example and the transmittance is shown by a curve a in FIG.

[Comparative example]
Next, the configuration of the liquid crystal display device 50 of the comparative example will be described with reference to FIG. The difference between the liquid crystal display device 50 of the comparative example and the liquid crystal display device 10A of the first embodiment is that the slit-shaped opening 2
7 and the width L of the upper electrode 26 positioned between the slit-shaped openings, and the other configurations are the same. For this reason, in the liquid crystal display device 50 of the comparative example, the same reference numerals are given to portions having the same configuration as the liquid crystal display device 10A of the first embodiment, and detailed description thereof is omitted.

Unlike the liquid crystal display device 10A of the embodiment, the liquid crystal display device 50 of the comparative example is different from the conventional FF.
As normally employed in S-mode liquid crystal display devices, the relationship between the width W of the slit-shaped opening 27 and the width L of the upper electrode 26 positioned between the slit-shaped openings is L <W. . The luminance distribution of the IVb-IVb portion of FIG. 2 of the liquid crystal display device 50 of this comparative example is shown in the curve b of FIG.
The relationship between the voltage applied between the lower electrode 23 and the upper electrode 26 of the liquid crystal display device 50 of the comparative example and the transmittance is shown by a curve b in FIG.

In the conventional liquid crystal display device, the transparent conductive electrode for preventing static electricity is provided on the display surface side of the color filter substrate CF (specifically, between the second transparent substrate of the color filter substrate CF and the polarizing plate). Except for being formed, it has the same configuration as the liquid crystal display device 50 of the comparative example. That is, in the conventional liquid crystal display device, the relationship between the width W of the slit-shaped opening and the width L of the upper electrode located between the slit-shaped openings is L as in the case of the liquid crystal display device 50 of the comparative example. <W. The luminance distribution of the portion corresponding to the IVb-IVb portion of FIG. 2 in this conventional liquid crystal display device is shown in the curve c of FIG. 4, and the voltage and transmittance applied between the lower electrode and the upper electrode. The relationship is shown by a curve c in FIG.

The following can be understood from the results shown in FIGS. That is, in the liquid crystal display device of the conventional example, as indicated by the curve c in FIG. 4 and the curve c in FIG. 5, the width of the in-plane luminance distribution is the smallest and the luminance is the highest. On the other hand, in the liquid crystal display device 50 of the comparative example, as shown by the curve b in FIG. 4 and the curve b in FIG. 5, the width of the in-plane luminance distribution is the largest and the luminance is the lowest. .

The difference in configuration between the liquid crystal display device of the conventional example and the liquid crystal display device 50 of the comparative example is that the transparent conductive electrode for preventing static electricity is formed on the liquid crystal layer LC side of the color filter substrate CF or on the display surface side. It is only formed. Therefore, in the conventional liquid crystal display device, the slit-like opening of the upper electrode formed on the array substrate side is simply formed by forming the transparent conductive electrode for preventing static electricity on the liquid crystal layer LC side of the color filter substrate CF. It can be seen that since the reverse twist domain at the end of the surface increases, the width of the in-plane luminance distribution increases, thereby reducing the transmittance. Such a phenomenon is caused by an electric field formed between the upper electrode and the lower electrode due to an electric field formed between the transparent conductive electrode for preventing static electricity and the upper electrode. This is probably because the twist of the liquid crystal molecules at the end of the slit-like opening and the upper surface of the upper electrode changes.

On the other hand, in the liquid crystal display device 10A of the embodiment, the relationship between the width W of the slit-shaped opening 27A and the width L of the upper electrode 26A portion between the slit-shaped openings 27A is L ≧ W. As shown by the curve a in FIG. 4 and the curve a in FIG. 5, intermediate characteristics between the liquid crystal display device of the conventional example and the liquid crystal display device 50 of the comparative example are obtained. That is, the liquid crystal display device 10A of the embodiment.
In the conventional liquid crystal display device, the width of the in-plane luminance distribution is larger and the luminance is lower, but the width of the in-plane luminance distribution is smaller than that of the liquid crystal display device 50 of the comparative example. And the brightness is high.

The difference in configuration between the liquid crystal display device 10A of the example and the liquid crystal display device 50 of the comparative example is that the relationship between the width W of the slit-shaped opening and the width L of the upper electrode portion between the slit-shaped openings is L The only difference is whether ≧ W (Example) or L <W (Comparative Example). Therefore, in the liquid crystal display device 10A of the example, even when the electric field distribution between the upper electrode and the lower electrode is changed by the electric field formed between the transparent conductive electrode for preventing static electricity and the upper electrode, the comparison is made. It is presumed that the reverse twist domain at the end of the slit-like opening of the upper electrode formed closer to the array substrate than the liquid crystal display device 50 of the example is difficult to increase. In the above embodiment, an example in which a rectangular opening is used as the slit-shaped opening is shown, but an oval shape,
Those having a banana shape with a tapered tip can also be used.

[Modification 1]
Next, a liquid crystal display device 10B according to a first modification to the liquid crystal display device 10A according to the embodiment will be described with reference to FIG. Note that in the liquid crystal display device 10B of the first modification, the same reference numerals are given to the same components as those of the liquid crystal display device 10A of the embodiment, and the detailed description thereof is omitted.

In the liquid crystal display device 10A of the embodiment, as shown in FIG. 1, the longitudinal direction of the slit-shaped opening 27A is inclined to the right by about 5 degrees with respect to the extending direction of the scanning line 17, and the right direction is increased. Two types of slit-shaped openings 27 are formed in the central portion.
A is configured such that one end is connected to form a horizontal V-shape. In the liquid crystal display device 10A having such a configuration, the slit-shaped opening 27A has the sub-pixels 12R and 12G.
, 12B have end portions at both ends. Since the end of the slit-shaped opening 27A becomes a reverse twist domain, it leads to a decrease in luminance.

Therefore, in the liquid crystal display device 10B of Modification 1, as shown in FIG. 6, the slit-shaped opening 27B is connected by connecting the slit-shaped opening 27B between the three sub-pixels 12R, 12G, and 12B forming one unit pixel. The number of the end portions is reduced. According to the liquid crystal display device 10B of Modification 1 having such a configuration, the width W of the slit opening 27B and the slit opening 2
From the liquid crystal display device 10A of the embodiment, the relationship between the width L of the upper electrode 26B portion between 7B is L ≧ W and the number of ends of the slit-shaped opening 27B is reduced. In addition, the reverse twist domain is reduced and the liquid crystal display device 10B having high luminance is obtained.

[Modification 2]
Next, a liquid crystal display device 10C of a second modification to the liquid crystal display device 10A of the embodiment will be described with reference to FIG. Note that in the liquid crystal display device 10C of the second modification, the same reference numerals are given to the same components as those of the liquid crystal display device 10A of the embodiment, and the detailed description thereof is omitted.

In the liquid crystal display device 10C of Modification 2, as shown in FIG. 7, the number of ends of the slit openings 27C is modified by connecting the slit openings 27C between all the sub-pixels adjacent in the row direction. The number of the liquid crystal display devices 10B is smaller than that of the first liquid crystal display device 10B. According to the liquid crystal display device 10C of Modification 2 having such a configuration, the width W of the slit opening 27C and the slit opening 27
Combined with the relationship between the width L of the upper electrode 26C portion between C and L ≧ W, and the fact that the number of ends of the slit-shaped opening 27C is further reduced, the liquid crystal display device 10A of the embodiment As a result, the reverse twist domain is reduced and the liquid crystal display device 10C having higher luminance can be obtained.

[Modifications 3 and 4]
In contrast to the liquid crystal display device 10A of the example and the liquid crystal display device 50 of the comparative example, when the transparent conductive electrode for preventing static electricity is formed on the liquid crystal layer LC side of the color filter substrate CF, the slit shape formed on the upper electrode It can be seen that the reverse twist domain at the end of the opening increases.
Therefore, if the transparent conductive electrode for preventing static electricity does not exist at the position corresponding to the edge of the upper electrode and the transparent conductive electrode for preventing static electricity exists only in other parts, Generation of the reverse twist domain due to the formation of the transparent conductive electrode can be suppressed.

There is no transparent conductive electrode for preventing static electricity at a position corresponding to the end of the upper electrode,
The liquid crystal display devices 10D and 10E of the modified examples 3 and 4 in which the transparent conductive electrode for preventing static electricity is formed so that the transparent conductive electrode for preventing static electricity exists only in other portions are shown in FIGS. explain. In FIG. 8 and FIG. 9, a transparent conductive electrode for preventing static electricity is also superimposed. Further, the same reference numerals are assigned to the same components as those of the liquid crystal display device 10A of the embodiment, and the detailed description thereof is omitted.

As shown in FIG. 8, in the liquid crystal display device 10D of Modification 3, the slit-shaped opening 27D formed in the upper electrode 26D has a vertical “<” shape, and the end of the slit-shaped opening 27D is A transparent conductive electrode 34D for preventing static electricity is formed so as to be exposed. Also in the liquid crystal display device 10D of Modification 3 having such a configuration, the relationship between the width W of the slit-shaped opening 27D and the width L of the upper electrode 26D portion between the slit-shaped openings 27D satisfies L ≧ W. And
Coupled with the fact that the reverse twist domain is less likely to occur at the end of the slit-shaped opening 27D, a liquid crystal display device 10D having higher luminance than the liquid crystal display device 10A of the embodiment is obtained.

In addition, as shown in FIG. 9, in the liquid crystal display device 10E of the modification 4, the slit-shaped opening 27E formed in the upper electrode 26E is formed in the same manner as in the liquid crystal display device 10A of the embodiment, Transparent conductive electrode 3 for preventing static electricity so that the end of slit-shaped opening 27E is exposed
4E is formed. Also in the liquid crystal display device 10E of Modification 4 having such a configuration, the relationship between the width W of the slit-shaped opening 27E and the width L of the upper electrode 26E portion between the slit-shaped openings 27E is L ≧ W. In combination with this, the reverse twist domain is less likely to occur at the end of the slit-shaped opening 27E, so that a liquid crystal display device 10E having higher luminance than the liquid crystal display device 10A of the embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10A-10E ... Liquid crystal display device 11 ... Unit pixel 12B, 12G, 12R ... Sub pixel 13 ... Polarizing plate 14 ... Polarizing plate 16 ... Transparent substrate 17 ... Scanning line 18 ... Gate insulating film 19 ... Semiconductor layer 20 ... Signal line 21 ... Passivation film 22 ... Flattening resin layer 2
DESCRIPTION OF SYMBOLS 3 ... Lower electrode 24 ... Contact hole 25 ... Interelectrode insulating film 26, 26A-26E ... Upper electrode 27, 27A-27E ... Slit-like opening 28 ... Orientation film 29 ... Transparent substrate 30 ...
Light shielding layer 31 ... Color filter layer 32 ... Overcoat layer 33 ... Alignment film 34A,
34D, 34E ... Transparent conductive electrode AR ... Array substrate CF ... Color filter substrate C
L ... Liquid crystal layer

Claims (5)

A first substrate and a second substrate disposed opposite to each other with a liquid crystal layer interposed therebetween;
The first substrate includes
A plurality of signal lines and scanning lines formed in a matrix in a state of being insulated from each other, and an upper electrode having a plurality of slit-like openings formed for each sub-pixel region partitioned by the scanning lines and the signal lines; The lower electrode formed on the substrate side through the upper electrode and an insulating layer,
In the second substrate, a liquid crystal display device comprising a transparent conductive electrode for preventing static electricity on the liquid crystal layer side,
When the width of the slit-shaped opening of the upper electrode is W, and the width of the linear upper electrode portion located between the slit-shaped openings is L,
L ≧ W
A liquid crystal display device satisfying the above conditions. The liquid crystal display device according to claim 1, wherein the slit-like openings are connected to each other between the plurality of sub-pixels forming a unit pixel. 2. The liquid crystal display device according to claim 1, wherein the slit openings are connected to each other between the plurality of sub-pixels forming a plurality of unit pixels. The said static conductive electrode for static electricity prevention is formed in the area | region except the edge part of the slit-shaped opening currently formed in the said upper electrode by planar view. A liquid crystal display device according to 1. 5. The transparent conductive electrode for preventing static electricity is electrically connected to one selected from a ground potential, a common wiring, the upper electrode, and the lower electrode.
A liquid crystal display device according to any one of the above.