Liquid crystal display device

A lateral-electric-field mode liquid crystal display device includes: substrates; a liquid crystal layer; plural scanning lines and plural data lines crossing on one of the substrates; plural pixels formed by the scanning lines and the data lines; at least one strip-shaped pixel electrode arranged in each pixel and extending along the data line or the scanning line; a common electrode located in a layer closer to the liquid crystal layer than the strip-shaped pixel electrodes so as to cover the scanning lines and the data lines; and a first rectangular pixel electrode connected with one end of each of the at least one strip-shaped pixel electrode to from a T shape. The first rectangular pixel electrode overlaps with corner parts of an opening section of the common electrode, where the corners are closer to the first rectangular pixel electrode than the other corners of the opening section.

TECHNICAL FIELD

The present invention relates to a liquid crystal display device. In particular, the present invention relates to a lateral-electric-field mode active matrix liquid crystal display device having a large aperture and being capable of realizing high resolution.

BACKGROUND

In recent years, there are provided lateral-electric-field mode liquid crystal display devices, which is represented by an IPS (In-plane Switching) liquid crystal display devices, on the market. Such liquid crystal display devices have excellent viewing angle and are widely used in many information terminals ranging from comparatively large-sized devices, such as a television set and a monitor, to portable devices such as a tablet and a smart phone. An IPS liquid crystal display device includes two kinds of strip-shaped (oblong-shaped) electrodes (strip-shaped pixel electrodes and strip-shaped portions of a common electrode) both arranged in parallel at intervals, when viewed from a position perpendicularly above the substrates, and drives liquid crystal molecules by using an electric field applied between each set of the strip-shaped pixel electrode and the strip-shaped portion of the common electrode. Such IPS liquid crystal display devices are characterized by a feature that there is no major change in the view even when the direction viewed from the observer has changed. This is because the observer does not perceive a great change of the orientation of liquid crystal molecules in such display devices even after the viewing angle has been changed.

Accordingly, IPS liquid crystal display devices are characterized by a great viewing angle. In addition, some of IPS liquid crystal display devices may employ a multi-domain structure as follows, in order to enhance their viewing angle characteristics. That is, such IPS liquid crystal display devices may employ a structure where an electrode in each pixel is bent by arranging a part and the other part of the two kinds of strip-shaped electrodes in the following manners and joining the both parts together. That is, a part of the two kinds of strip-shaped electrodes is arranged so as to produce an electric field which is to be applied to the liquid crystal and forms +θ° angle between the direction of the electric field and the initial orientation of liquid crystal molecules. The other part of the two kinds of strip-shaped electrodes is arranged so as to produce the electric field which is to be applied to the liquid crystal and forms −θ° angle between the direction of the electric field and the initial orientation of liquid crystal molecules. It should be noted that the strip-shaped electrodes (strip-shaped pixel electrodes and strip-shaped portions of the common electrodes) do not need to have independent bodies. As far as edge portions of a pair of the opposing electrodes are in parallel, the end portion of each electrode may have any shape other than a strip shape, such that the end portions may be connected together, or a portion except the portion where the pair of electrodes are in the opposing positions may have a different shape.

However, in this multi-domain structure, each pixel includes a bent part at the junction of the electrode portion for the +θ° angle and another electrode portion for the −θ° angle. The bent part forms a domain boundary between a liquid crystal domain where there is a clockwise deformation and the liquid crystal domain where there is a counterclockwise deformation, which causes disclination of the liquid crystal molecules and results in a reduction of the transmittance.

A liquid crystal display device includes a plurality of scanning lines and a plurality of data lines both arranged on one of a pair of substrates, and a plurality of pixels. Each of the pixels is formed by a divided area whose boundary is defined by each two scanning lines and each two data lines out of the scanning lines and the data lines. The smaller the size of each pixel is, the larger the ratio of the area of scanning lines and data lines in each pixel, and as a result, the aperture ratio decreases.FIG. 20is a graph showing a relationship between an aperture ratio and a pixel size wherein each of the scanning line width and the data line width is set at a constant value of 10 μm and a region of a pixel except the wiring area is assumed as an aperture. As can be understood from this relationship, the aperture ratio decreases prominently especially when the pixel size decreases to 100 μm or less. Accordingly, in liquid crystal display devices employing the multi-domain structure described above, there arises a problem that a decrease in the relative transmittance due to the bent part of an electrode in each pixel becomes too significant to be disregarded.

In order to avoid this problem, it is advantageous for the liquid crystal display devices to adopt a structure of a single domain where an electrode in each pixel is not bent. However, a use of the single domain structure results in loss of the outstanding viewing angle characteristics obtained with a multi-domain structure. To solve this problem, structures in which liquid crystal molecules rotate in two directions within each pixel without using a bent electrode, are described in Japanese Unexamined Patent Application Publications (JP-A) No. H09-105908 (FIGS. 32 and 36) and JP-A No. 2004-271971 (FIGS. 45, 46 and 48).

As a representative example of the conventional techniques,FIGS. 21A and21B illustrate pixel structures disclosed in JP-A No. JP H09-105908 (in FIGS. 32 and 36), respectively, where upper and lower sides of the each figure are reversed in comparison with the original figures in order to simplify the following description. Each ofFIGS. 21A and21B shows common electrode101, pixel electrode102, electric fields103and104, common electrode line105, data line106, source electrode107, drain electrode108, amorphous silicon (TFT channel region)109, scanning line (gate line)110, and boundary111of a black matrix. In the above structures, each or one of the common electrode101and the pixel electrode102additionally has an edge portion with an inclining edge such that one electrode gradually approaches to the other electrode as getting closer to the pixel end. In the approached region, the electrodes produce electric fields103,104in two different directions. The document describes that such a structure makes two directions of rotation of liquid crystal molecules within a pixel, which can realize a multi-domain structure without using a bent electrode in each pixel. However, since each or one of the common electrode101and the pixel electrode102additionally has the edge portion with an inclining edge, the opening decreases in comparison with an area which could be used as the opening in the original structure, and it causes a decrease of the transmittance.

JP-A No. 2004-271971 also discloses in FIGS. 44 and 47 the above-described pixel structure that liquid crystal molecules rotates in two different directions within each pixel without using bent electrodes. As a representative example of the conventional techniques,FIG. 22shows a pixel structure disclosed in JP-A No. 2004-271971 (in FIG. 44), where some components that are not used in the following description, such as accumulated capacitance lines and others, are omitted.FIG. 20shows common electrode101, pixel electrode102, electric fields103and104, data line106, scanning line (gate line)110, semiconductor layer112, and through holes113. Also in the disclosed structure, one electrode gradually approaches the other electrode, and the approaching region produces the electric fields103and104in two different directions. The document describes that such a structure makes two directions of rotation of liquid crystal molecules within a pixel, which can realize a multi-domain structure without using a bent electrode in each pixel. However, this structure also causes a decrease of the transmittance for the same reason as the reason described above.

Furthermore, these structures can cause the decrease of the transmittance for another reason, and the reason will be described with reference toFIGS. 23 and 24.FIG. 23is an enlarged view of a region surrounded with broken lines inFIG. 22. In this structure, the common electrode101and the pixel electrode102are formed in different layers and there are some regions where the common electrode101and the pixel electrode102partly overlaps with each other within a pixel. In the overlapping regions and in specific neighboring regions, electric fields114and115in unwanted directions, which are different from those of the intended electric fields103and104, are produced. These electric fields114and115are referred to as so-called fringe electric fields. Such a structure causes a rotation of liquid crystal molecules, which exist in an area affected by the electric fields114and115, in a direction opposite to the intended direction, which produces a reverse rotation domain117. On the boundary of the reverse rotation domain117and the forward rotation domain118, there are produced disclination116, causing a decrease of the transmittance.

FIG. 24illustrates situations of the disclination116, the reverse rotation domain117and the forward rotation domain118. Under the situation that a reverse rotation domain exists in proximity to the forward rotation domain, an external force, such as finger pressing, which has been temporarily applied onto the display screen during the drive of the display screen, makes a disturbance of the orientation of the liquid crystal molecules during the application of the force. When the screen is released from the external force, the liquid crystal molecules try to return to the original orientation again. However, it more likely causes a phenomena that the forward rotation domain is reduced as compared to a state before the external force is applied, and reversely, the reverse rotation domain becomes larger by an amount corresponding to the reduction and stabilizes in such a state. It causes a difference of the display condition between a display state before an external force is applied and a display state after an external force of finger pressing. As a result, there occurs a display issue recognized as finger pressing marks. This phenomenon causes a remarkable deterioration of the liquid crystal display device in the image quality.

The present invention seeks to solve the problems.

SUMMARY

In view of the above-described problems, there are provided illustrative IPS liquid crystal display devices which have a large aperture and exhibit an excellent viewing angle in spite of their small pixel sizes, and can avoid appearance of finger pressing marks thereon.

A lateral-electric-field mode liquid crystal display device according to a first aspect of the present invention comprises: a pair of substrates; a liquid crystal layer put between the substrates; a plurality of scanning lines and a plurality of data lines, both extending in straight lines and crossing each other on one of the substrates; and a plurality of pixels formed by the scanning lines and the data lines and arrayed in matrix. The liquid crystal display device further comprises at least one strip-shaped pixel electrode arranged in each of the pixels and extending along one of the data lines or one of the scanning lines; and a common electrode having a grid form, located in a layer closer to the liquid crystal layer than the strip-shaped pixel electrodes so as to cover the scanning lines and the data lines, and including an opening section located in each of the pixels. Each of the at least one strip-shaped pixel electrode and a part of the common electrode extending in parallel with an extending direction of the at least one strip-shaped pixel electrode forms therebetween an electric field to be applied to the liquid crystal layer, where the electric field is in substantially parallel with a surface direction of the substrates. The liquid crystal display device further comprises a first rectangular pixel electrode arranged in each of the pixels, being greater in width than the at least one strip-shaped pixel electrode, and connected with one end of each of the at least one strip-shaped pixel electrode to from a T shape. The first rectangular pixel electrode overlaps with corner parts of the opening section of the common electrode, where the corner parts concerned are closer to the first rectangular pixel electrode than the other corner parts of the opening section.

When a plurality of the strip-shaped pixel electrodes are arranged in each of the pixels in the first aspect of the present invention, the first rectangular pixel electrodes connected with the respective strip-shaped pixel electrodes may be connected together, and a strip-shaped common electrode may be further arranged between the neighboring strip-shaped pixel electrodes in each of the pixels, where both ends of the strip-shaped common electrode are connected with the common electrode having the grid form.

A lateral-electric-field mode liquid crystal display device according to a second aspect of the present invention, comprises a pair of substrates; a liquid crystal layer put between the substrates; a plurality of scanning lines and a plurality of data lines, both extending in straight lines and crossing each other on one of the substrates; and a plurality of pixels formed by the scanning lines and the data lines and arrayed in matrix. The liquid crystal display device further comprises at least one strip-shaped pixel electrode arranged in each of the pixels and extending along one of the data lines or one of the scanning lines; and a common electrode having a grid form, located in a layer closer to the liquid crystal layer than the strip-shaped pixel electrodes so as to cover the scanning lines and the data lines, and including an opening section located in each of the pixels. Each of the at least one strip-shaped pixel electrode and a part of the common electrode extending in parallel with an extending direction of the at least one strip-shaped pixel electrode forms therebetween an electric field to be applied to the liquid crystal layer, where the electric field is in substantially parallel with a surface direction of the substrates. The liquid crystal display device further comprises a projecting-shaped pixel electrode arranged in each of the pixels and including at least one projecting part and a main part being greater in width than the at least one strip-shaped pixel electrode, where the projecting-shaped pixel electrode is connected with one end of each of the at least one strip-shaped pixel electrode at a position outside the opening section. The at least one projecting part overlaps with at least one corner part of the opening section of the common electrode, where the at least one corner part is closer to the projecting-shaped pixel electrode than the other corner parts of the opening section.

When a plurality of the strip-shaped pixel electrodes are arranged in each of the pixels in the second aspect of the present invention, the projecting-shaped pixel electrodes connected with the respective strip-shaped pixel electrodes may be connected together, and a strip-shaped common electrode may be further arranged between the neighboring strip-shaped pixel electrodes in each of the pixels, where both ends of the strip-shaped common electrode are connected with the common electrode having the grid form.

In the first and second aspects of the present invention, the common electrode may include protruding parts each protruding from the common electrode inside the opening section in each of the pixels. Further, the liquid crystal display device may further comprise a second rectangular pixel electrode arranged in each of the pixels, being greater in width than the at least one strip-shaped pixel electrode, and connected with the other end of each of the at least one strip-shaped pixel electrode to from a T shape, where the second rectangular pixel electrode overlaps with one of the protruding parts of the common electrode in each of the pixels.

Here, a region surrounded by the strip-shaped pixel electrode, the first rectangular pixel electrode or the projecting-shaped pixel electrode, and the second rectangular pixel electrode, and the common electrode is referred to as a “column”. There are a plurality of columns within each pixel. Liquid crystal molecules undergo twist deformation inside the column mostly. At this time, each of the plurality of columns corresponds to either one of the two areas of different twist deformation orientations. That is, by using a pixel structure as described above, it is possible to obtain a lateral-electric-field mode liquid crystal display device having outstanding viewing angle characteristics and a large aperture and that avoids appearance of finger pressing marks thereon. This is because there are columns with different twist deformation orientations of liquid crystal in each pixel.

In the first aspect or the second aspect of the present invention, by locating the common electrode closer to the liquid crystal layer, an insulating layer between the pixel electrodes and the common electrode can be used in common with an interlayer insulating film between the common electrode and the data lines. As a result, the liquid crystal display device can be made at a lower cost since the number of times of formation of the insulating layer can be decreased.

A lateral-electric-field mode liquid crystal display device according to a third aspect of the present invention comprises: a pair of substrates; a liquid crystal layer put between the substrates; a plurality of scanning lines and a plurality of data lines, both extending in straight lines and crossing each other on one of the substrates; and a plurality of pixels formed by the scanning lines and the data lines and arrayed in matrix. The liquid crystal display device further comprises a common electrode having a grid form, covering the scanning lines and the data lines, and including an opening section located in each of the pixels; and a strip-shaped pixel electrode arranged in each of the pixels, located in a layer closer to the liquid crystal layer than the common electrode and extending along one of the data lines or one of the scanning lines. The strip-shaped pixel electrode and a part of the common electrode extending in parallel with an extending direction of the strip-shaped pixel electrode forms therebetween an electric field to be applied to the liquid crystal layer, where the electric field is in substantially parallel with a surface direction of the substrates. The liquid crystal display device further comprises a rectangular pixel electrode arranged in each of the pixels, being greater in width than the strip-shaped pixel electrode, and connected with one end of the strip-shaped pixel electrode to from a T shape. The rectangular pixel electrode overlaps with the common electrode while not extending inside the opening section.

In the third aspect of the present invention, by locating the pixel electrodes closer to the liquid crystal layer, an insulating layer may be located between the pixel electrodes and the data lines, which can avoid a short circuit between the pixel electrodes and the data lines coming from pattern collapsing of the pixel electrodes or the data lines.

In the first to third aspects of the present invention, an initial orientation of liquid crystal molecules in the liquid crystal layer can be substantially identical with an extending direction of the strip-shaped pixel electrodes.

Under the condition, it is necessary to use liquid crystal molecules having positive dielectric anisotropy (hereafter referred to as “positive liquid crystal”, and similarly, liquid crystal molecules having negative dielectric anisotropy are referred to as “negative liquid crystal”). A low voltage drive and a high speed response can be attained since positive liquid crystal generally has large dielectric anisotropy and low viscosity as compared to negative liquid crystal.

Alternatively, in the first to third aspects of the present invention, an initial orientation of liquid crystal molecules in the liquid crystal layer can be substantially identical with a direction perpendicular to an extending direction of the strip-shaped pixel electrodes.

Under the condition, it is necessary to use negative liquid crystal. Homogeneously aligned negative liquid crystal causes almost no deformations in an electric field having a component in a direction perpendicular to the substrate surface. Therefore, the homogenous alignment causes twist deformation with respect to an electric field having a component in a direction parallel to the substrate side without causing deformations in an electric field having a component in a direction perpendicular to the substrate surface. Thus, it is possible to obtain outstanding display properties about viewing angle.

In the first to third aspects of the present invention, both the pixel electrodes and the common electrode may be transparent.

By using a transparent electrically-conductive film for the electrodes, light can pass through a part of the electrodes, which realizes an increase of the transmittance.

Accordingly, there are provided, as embodiments of the present invention, illustrative IPS liquid crystal display devices which have a large aperture and exhibit an excellent viewing angle characteristics in spite of their small pixel size, and can avoid appearance of finger pressing marks thereon.

Other features of illustrative embodiments will be described below.

DETAILED DESCRIPTION

Illustrative embodiments of liquid crystal display devices will be described below with reference to the drawings. It will be appreciated by those of ordinary skill in the art that the description given herein with respect to those figures is for exemplary purposes only and is not intended in any way to limit the scope of potential embodiments may be resolved by referring to the appended claims.

As described in the descriptions of the background, in an IPS liquid crystal display device, the aperture ratio becomes smaller with a reduction of a pixel size. In order to solve the problem, a pixel structure that rotates liquid crystal molecules in two directions within a pixel by using non-bent electrodes has been proposed. However, the conventional structure still has display issues of a decrease of transmittance due to a region that is occupied by the electrodes but was available as a part of an opening before the above-described countermeasure, or display issues of a decrease of transmittance and finger pressing marks due to the liquid crystal molecules rotating in a direction opposite to the intended direction.

In view of that, an illustrative liquid crystal display device as one embodiment of the present invention includes a strip-shaped pixel electrode arranged in each pixel and extending along one of the data lines or one of the scanning lines; and a common electrode having a grid form, located in a layer closer to the liquid crystal layer than the strip-shaped pixel electrodes so as to cover at least the scanning lines and the data lines. If the plurality of the strip-shaped pixel electrodes are arranged in each pixel, a strip-shaped common electrode may be further arranged between the neighboring strip-shaped pixel electrodes in each pixel, where both ends of the strip-shaped common electrode is connected with the common electrode having the grid form. In each pixel, a first rectangular pixel electrode or a projecting-shaped pixel electrode is arranged. In the case of the first rectangular pixel electrode, the first rectangular pixel electrode is greater in width than the strip-shaped pixel electrode, and is connected with one end of the strip-shaped pixel electrode to from a T shape. The first rectangular pixel electrode overlaps with corner parts of the opening section formed in the common electrode, where the corner parts concerned are closer to the first rectangular pixel electrode than the other corner parts of the opening section. In the case of the projecting-shaped pixel electrode, the main part of the projecting-shaped pixel electrode is greater in width than the strip-shaped pixel electrode, and the projecting-shaped pixel electrode is connected with one end of the strip-shaped pixel electrode at a position outside the opening section. One or both projecting parts of the projecting-shaped pixel electrode overlap with at one or both corner parts of the opening section of the common electrode, respectively, where the at least one corner part is closer to the projecting-shaped pixel electrode than the other corner parts of the opening section.

As another embodiment, an illustrative liquid crystal display device includes a common electrode having a grid form and covering at least the scanning lines and the data lines. In each pixel, a strip-shaped pixel electrode is arranged in a layer closer to the liquid crystal layer than the common electrode and extends along one of the data lines or one of the scanning lines. If the plurality of the strip-shaped pixel electrodes are arranged in each pixel, a strip-shaped common electrode may be further arranged between the neighboring strip-shaped pixel electrodes in each pixel, where both ends of the strip-shaped common electrode is connected with the common electrode having the grid form. In each pixel, a rectangular pixel electrode is arranged, where the rectangular pixel electrode is greater in width than the strip-shaped pixel electrode, and connected with one end of the strip-shaped pixel electrode to from a T shape. The rectangular pixel electrode overlaps with the common electrode while not extending inside the opening section.

An illustrative liquid crystal display device according to EXAMPLE 1 will be described now with reference toFIGS. 1 to 4.FIG. 1is a plan view illustrating a structure of one pixel of a liquid crystal display device according to EXAMPLE 1, where unit pixel27is indicated by an area surrounded by broken lines.FIG. 2is a cross-sectional view of the liquid crystal display device, taken along line II-II shown inFIG. 1, and further illustrates a liquid crystal layer and opposing substrates.FIG. 3is an enlarged view of columns and their circumference shown inFIG. 1.FIG. 4is a further enlarged diagram of upper and lower parts of the pixel inFIG. 3.

An illustrative liquid crystal display device according to EXAMPLE 1 shown inFIGS. 1 to 4will be described now in detail. The liquid crystal display device includes first transparent insulating substrate11, second transparent insulating substrate19, and a layer of liquid crystal9put between the pair of substrates. On the first transparent insulating substrate11, plural scanning lines6and plural data lines5are arranged to form plural pixels, where two neighboring scanning lines6and two neighboring data lines5that cross each other form the boundary of each pixel. There is further provided common electrode1having a grid form. The common electrode1is formed in a layer closer to the layer of liquid crystal9than the strip-shaped pixel electrodes2so as to cover the scanning lines6and the data lines5. In each pixel, there are one strip-shaped pixel electrode2and parts of common electrode1covering the data lines5, which are arranged so that the parts of common electrode1alternate with the strip-shaped pixel electrodes2. The strip-shaped pixel electrode2is arranged in the middle of each pixel and extends along the extending direction of the data lines5. The strip-shaped pixel electrode2is smaller in length of the longitudinal direction than a part of the common electrode1covering the data line5. In each pixel, there is a rectangular pixel electrode (first rectangular pixel electrode2b) connected to one end of the strip-shaped pixel electrode2to form a T shape. That is, the first rectangular pixel electrode2bwhich is greater in width than a strip part of the strip-shaped pixel electrode is connected substantially perpendicularly (at right angles) to one end of the strip-shaped pixel electrode2to form a T shape. Furthermore, the first rectangular pixel electrode2boverlaps with two corner parts of opening section28formed (surrounded) by the common electrode1in each pixel. In an area of each pixel on the side of the other end of the strip-shaped pixel electrode2in its longitudinal direction, there are provided a part of common electrode (protruding common electrode1a) protruding inside opening section28from a part of common electrode1covering scanning line6; and a rectangular pixel electrode (second rectangular pixel electrode2a) connected to the other end of the strip-shaped pixel electrode. The rectangular pixel electrode (second rectangular pixel electrode2a) is greater in size than the protruding part of common electrode (protruding common electrode1a) and is arranged so as to cover the protruding part. In other words, the second rectangular pixel electrode2ais greater in width than the strip part of the strip-shaped pixel electrode2, is connected to the other end of the strip-shaped pixel electrode2to form a T shape, and covers the protruding common electrode1a. In this structure, molecular orientation7of liquid crystal in this structure is in the extending direction of the strip-shaped pixel electrode2.

Here, positional relationships between common electrode1covering scanning lines6and data lines5, protruding common electrode1a, strip-shaped pixel electrode2, second rectangular pixel electrode2a, and first rectangular pixel electrode2bwill be described in detail usingFIG. 3andFIG. 4.FIG. 3is an enlarged view of columns and their circumference within a pixel illustrated inFIG. 1.FIG. 4is a further enlarged view of the upper part and the lower part of the pixel illustrated inFIG. 3.

First,FIG. 3will be described now. In a lateral-electric-field mode liquid crystal display device of having such a structure, a potential difference made between the common electrode1and strip-shaped pixel electrode2produces a lateral electric field8. Other than the electric field, there are various electric field produced in a pixel, such as lateral electric fields21aand21bin regions where common electrode1is near one of second rectangular pixel electrode2aand first rectangular pixel electrode2b, and fringe electric fields22aand22bproduced by one of common electrode1and the protruding common electrode1a, and one of second rectangular pixel electrode2aand first rectangular pixel electrode2b. In special, the fringe electric fields22aand22bplay an important role in the present example, for the following reason. In this structure, molecular orientation7of liquid crystal is perpendicular (at 90 degrees) to the direction of lateral electric field8. The lateral electric field8produced in the structure acts on the liquid crystal in the initial orientation state to cause twist deformation. However, since the start of deformation due to the fringe electric field of22ais earlier, liquid crystal located in the right column as shown inFIG. 3is affected by the fringe electric field22aand deforms in the direction of ii (from9ato9b). Liquid crystal located in the left column is similarly affected by the fringe electric field22band deforms in the direction of i (from9ato9b). That is, though the direction of the lateral electric field8is perpendicular (at 90 degrees) to the molecular orientation7of liquid crystal, the twist deformation orientation of the liquid crystal is different between two columns constituted by the strip-shaped pixel electrode2and the common electrode1.

Giving a supplementary explanation, the liquid crystal located in the column at the right side of the strip-shaped pixel electrode2deforms in the direction of ii then, and the lateral electric field21ain a direction opposite to this direction is produced in the column. However, since the lateral electric field21ais weak as compared to the fringe electric field22awhich is in its immediate proximity, liquid crystal located in a region where the lateral electric field21ais active does not cause deformation in the direction of the lateral electric field21a, and thus the liquid crystal deforms in the direction of ii. Similarly, liquid crystal located in the column at the left of the strip-shaped pixel electrode2deforms in the direction of i, and the lateral electric field21bin the direction opposite to this direction is produced in the column. However, since the lateral electric field21bis also weak when compared to the fringe electric field22bthat is in immediate proximity of the lateral electric field21b, liquid crystal located in a region where the lateral electric field21bfunctions does not cause deformation in the direction of the lateral electric field21band deforms in the direction of i. To be exact, other than the fringe electric fields22aand22bin the oblique directions, there are produced other fringe electric fields in this pixel, which are fringe electric fields in the extending direction of data lines5and the extending direction of scanning lines6. However, those fringe electric fields are omitted here since the fringe electric fields do not affect the twist deformation direction of the liquid crystal.

Next,FIG. 4will be described now.FIG. 4illustrates protruding common electrode1a, second rectangular pixel electrode2aand the first rectangular pixel electrode2b. Distance d1of an extending amount of the second rectangular pixel electrode2aout from the protruding common electrode1aand distance d2of an extending amount of the first rectangular pixel electrode2bout from the common electrode1should be at least 0 or larger than 0. Here, the distances are set at 2 μm. In addition, it is sufficient if the protruding distance d3of the protruding common electrode1ais from 2 μm to 3 μm. However, here the distance is set at 5 μm and the width d4is set at 3 μm.

Outstanding viewing angle characteristics similar to the multi-domain structure in which electrodes are bent can be obtained through implementing the above pixel structure. This is because there are a plurality of columns having different twist deformation directions of the liquid crystal within a pixel. Furthermore, there is no reduction in the opening region since the edge part of each electrode are not formed in an oblique direction as described in the descriptions aboutFIGS. 21 and 22. In addition, since the liquid crystal twist direction is controlled by the fringe electric fields22aand22b, it is possible to obtain an IPS liquid crystal display device that is resistive to finger pressing marks and can realize a quick response.

Further, in the present example, common electrode1is located closer to the liquid crystal layer than pixel electrodes2. By placing the common electrode1at a nearer position to the liquid crystal layer, an insulating film between pixel electrodes and common electrode1can be used in common with an interlayer insulating film between common electrode1and data lines5. As a result, the pixel structure can be formed at a lower cost since the number of times of formation of the insulating layer can be lessened.

The above serves as a detailed description of a structure of EXAMPLE 1. An example of the manufacturing method will also be described now.

First, a glass substrate being first transparent insulating substrate11is prepared. On the substrate, a first metal layer formed of molybdenum alloy is formed to be 300 nm in thickness though a sputtering technique and is patterned into scanning lines6.

Next, on the resulting structure, 100 nm thickness of silicon oxide is deposited to be a gate insulating film12, and then 300 nm thickness of silicon nitride, 170 nm thickness of i-a-Si (intrinsic amorphous Silicon) and 30 nm thickness of n-a-Si (n-type amorphous Silicon) are deposited successively by a PCVD (Plasma Chemical Vapor Deposition) technique. Laminated films of i-a-Si and n-a-Si are partly removed by etching, leaving a portion that serves as a thin film semiconductor layer4.

Next, on the resulting structure, a transparent electrically-conductive film made of a transparent material such as ITO (Indium Tin Oxide) is formed, and it is formed into 40 nm thickness of pixel electrodes each having a strip shape extending in a direction perpendicular (at 90 degrees) to the extending direction of scanning lines6. In this process, second rectangular pixel electrodes2aand first rectangular pixel electrodes2bare also formed simultaneously at this time.

Next, a film of molybdenum alloy is formed as a second metal layer in a thickness of 300 nm and is patterned into data lines5and source electrodes3. Each data line5is arranged so as not to overlap with strip-shaped pixel electrode2, second rectangular pixel electrode2a, and first rectangular pixel electrode2b, and is arranged in parallel with strip-shape pixel electrode2. Each source electrode3is arranged so as to have a region partly overlapping with the first rectangular pixel electrode2band to send an electric current to the first rectangular pixel electrode2b. It should be noted that a TFT (Thin Film Transistor) is composed of a part of scanning line6, gate insulating film12, thin film semiconductor layer4, a part of data line5, and source electrode3.

Next, an unnecessary part of the n-a-Si layer in the thin film semiconductor layer4of a TFT is removed by etching using the second metal layer as a mask.

Next, on the resulting structure, 500 nm thickness of silicon nitride is deposited to form a passivation film13.

Next, in order to expose the metal layer in terminal portions of data lines5and scanning lines6that are led around the display screen, the corresponding parts of gate insulating film12and the passivation film13are removed by etching.

Next, 80 nm thickness of common electrode1is formed out of a transparent electrically-conductive film made of transparent material, such as ITO (Indium Tin Oxide), so as to cover scanning lines6and data lines5. In this process, protruding common electrodes1aare simultaneously formed at this time. Furthermore, the common electrode1is electrically-conductive with a common-electrode line via a contact hole, where the common-electrode line is formed out of the first metal layer and the second metal layer, or any one of the metal layers in the periphery of the display screen. The common electrode1may be patterned so as to cover a part of scanning lines6except an area directly above the channel section of each TFT.

On the resulting TFT-side substrate formed as described above, oriented film14is formed by application and baking process. Meanwhile, on the second transparent insulating substrate19which serves as an opposing substrate, there are formed black matrix18, color layer17which serves as a color filter, overcoat16, and pillar-shaped spacers (not illustrated in the drawings) to ensure a space between the opposing substrate and the TFT-side substrate. On the resulting structure, oriented film15is further formed by application and baking process. Then, rubbing treatment is carried out onto the orientated films14and15of both substrates in a direction perpendicular (at 90 degrees) to the extending direction of scanning lines6to define molecular orientation7of liquid crystal. Both substrates are adhered together and sealing material is solidified on the periphery of the joined substrates. Then, liquid crystal9is poured between the substrates and a sealing process is carried out. Herein, the liquid crystal cell gap is set at 3.5 μm, and liquid crystal9(positive liquid crystal) with refractive index anisotropy of Δn=0.09 and dielectric anisotropy of Δ∈=10 is used. The process of pouring in liquid crystal9is to be carried out taking sufficient injection time so that the liquid crystal9enters into the cell sufficiently. The sealing process is carried out while pressurizing such that there is a predetermined pressure in the liquid crystal cell. Of course, by using a liquid crystal dropping technique, it is also possible to carry out the steps of: filling the cell with liquid crystal9; adhering both the substrates together; and sealing the periphery, after rubbing treatment for both the substrates.

On the TFT-side substrate of the liquid crystal display panel manufactured as described above, polarization plate10is adhered, where its polarization axis matches with molecular orientation7of liquid crystal being as the rubbing direction of the liquid crystal. On the opposing substrate, polarization plate20is adhered so as to form a crossed Nicols arrangement.

Furthermore, a necessary driver is mounted on the periphery of the liquid crystal display panel, and the liquid crystal display panel is assembled with a backlight and a signal processing board in an appropriate form, to manufacture an active matrix liquid crystal display device.

The liquid crystal display device operates in an IPS (In-Plane Switching) mode in which each pair of a part of common electrode1extending in the direction of data line5and strip-shaped pixel electrode2forms between them lateral electric field8that is substantially parallel to the surface direction of the substrates, and the lateral electric field8makes an in-plane twist deformation of liquid crystal which has been homogenously oriented in the rubbing direction, so that the amount of transmitted light for each pixel is controlled properly.

In this EXAMPLE 1, the resolution applied is of the horizontal resolution of 1024×3 (RGB) pixels and the vertical resolution of 768 lines, corresponding to XGA size. Pixel size is set at 69 μm, the data line width is set at 3 μm, the common electrode width on the data line is set at 9 μm, and the pixel electrode width is set at 3 μm. In this case, the gap between the strip-shaped pixel electrode2and a part of the common electrode1extending along the data line5is set at 5.5 μm.

The setting values described above are those just for use in this EXAMPLE 1. Those values are not limited in particular and should be set as appropriate. For example, the metal layer is made of molybdenum alloy in this EXAMPLE 1. However, the metal layer is not limited to this and may be made of aluminum alloy or the like. Further, in EXAMPLE 1, the manufacturing process takes the steps of after forming the thin film semiconductor layer4, formation of pixel electrodes2, source electrodes3and data lines5out of a transparent electrically-conductive film, and etching of an unnecessary part of the n-a-Si layer of the thin film semiconductor layer4, in this order. However, the process is not limited to this. For example, the process may take the steps of after forming the thin film semiconductor layer4, formation of source electrodes3and data lines5, etching of an unnecessary part of the n-a-Si layer of the thin film semiconductor layer4, and formation of pixel electrodes out of a transparent electrically-conductive film, in this order.

EXAMPLE 2 will be described now usingFIGS. 5, 6 and 7.FIG. 5is a plan view illustrating a structure of one pixel of the liquid crystal display device according to EXAMPLE, where unit pixel27is indicated by an area surrounded by broken lines.FIG. 6is a cross-sectional view taken along line VI-VI shown inFIG. 5and further illustrates a liquid crystal layer and opposing substrates.FIG. 7is an enlarged view illustrating columns and their circumference in a pixel inFIG. 6. EXAMPLE 2 shown inFIGS. 5, 6 and 7will be described now in detail.

In EXAMPLE 1, the pixel electrodes are formed out of a transparent electrically-conductive film as shown in, for example,FIG. 1. Meanwhile, in EXAMPLE 2, the pixel electrodes are formed out of the second metal layer as shown inFIGS. 5, 6 and 7. That is, in the process of forming the second metal layer, data lines5, source electrodes3, strip-shaped pixel electrodes2c, second rectangular pixel electrodes2d, and first rectangular pixel electrodes2eare simultaneously formed. Thereby, it is possible to omit the steps of forming and patterning a transparent electrically-conductive film in order to form pixel electrodes required in EXAMPLE 1. Accordingly, it is possible to obtain advantageous effects such as a reduction of tact time, lower costs due to reduced manufacturing steps, and a reduced defective fraction due to reduction of chances of a foreign object entering.

EXAMPLE 3 will be described now usingFIGS. 8, 9 and 10.FIG. 8is a plan view illustrating a structure of one pixel of the liquid crystal display device according to EXAMPLE 3, where unit pixel27is indicated by an area surrounded by broken lines.FIG. 9is an enlarged view illustrating a region around the circumference of data line5inFIG. 8.FIG. 10is a plan view illustrating a modified structure of one pixel in which a part of the common electrode that covers the data line is not hollowed out, where unit pixel27is indicated an area surrounded by broken lines. EXAMPLE 3 shown inFIGS. 8, 9 and 10will be described now in detail.

In EXAMPLE 1, strip-shaped pixel electrode2was arranged such that its extending direction is parallel to the extending direction of data lines5, in each pixel. Meanwhile, in EXAMPLE 3, the strip-shaped pixel electrode2is arranged such that its extending direction is parallel to the extending direction of scanning lines6in each pixel as shown inFIG. 8. In each pixel, a plurality of strip-shaped pixel electrodes2are arranged, and strip-shaped common electrode1bis further arranged in substantially the middle of the neighboring strip-shaped pixel electrodes2. In this structure, neighboring first rectangular pixel electrodes2bare connected together, and both end portions of the strip-shaped common electrode1bare connected to common electrode1having a grid form.FIG. 8illustrates a situation where two strip-shaped pixel electrodes2and one strip-shaped common electrode1bare arranged in one pixel. However, three or more strip-shaped pixel electrodes2may be arranged in one pixel and strip-shaped common electrode1bmay be arranged between each pair of neighboring strip-shaped pixel electrodes2.

Furthermore, a part of common electrode1which was prepared to cover the data line in the above examples can include a hollowed region23if molecular orientation7of liquid crystal is set to be the same as the extending direction of strip-shaped common electrodes1band strip-shaped pixel electrodes2. The reason will be described now usingFIG. 9.FIG. 9is an enlarged view of a region around the data line5inFIG. 8. The molecular orientation7of liquid crystal is perpendicular (at 90 degrees) to the extending direction of data lines5and the initial orientation state9aof the liquid crystal is as shown inFIG. 9. When a driving signal is input into the data line5in this structure, electric field24acts between the data line5and the common electrode1. However, since the direction of the electric field24is the same as molecular orientation7of liquid crystal, the liquid crystal becomes in state9cwhere the twist deformation is not carried out. Therefore, since the liquid crystal located in the hollowed out region23of the common electrode does not cause twist deformation even when a driving signal is input into the data line5, and light does not pass through this region, which does not cause deterioration of image quality.

Accordingly, in EXAMPLE 3, the region where the common electrode1is arranged over the data line is reduced and the capacity to be provided between the data line5and the common electrode1is reduced also, and thus there is an advantageous effect of reducing an unintended capacity coupling. As a result, the image quality degradation resulting from fluctuation of the common electrode potential under the influence of data signals is suppressed and low power consumption can be attained due to reduction of load carrying capacity. Of course, there is no problem with regards to a display element if a part of common electrode1that is arranged to cover the data line5as shown inFIG. 10is not hollowed out. In EXAMPLE 3, strip-shaped pixel electrode2and strip-shaped common electrode1bare formed in a direction parallel to the extending direction of the scanning line6sin each pixel. However, the strip-shaped pixel electrode2and the strip-shaped common electrode1bmay be formed so as to extend in a direction parallel to the extending direction of data lines5.

EXAMPLE 4 will be described now usingFIGS. 11 and 12.FIG. 11andFIG. 12are plan views illustrating a structure of one pixel of the liquid crystal display device according to EXAMPLE 4, where unit pixel27is indicated by an area surrounded by broken lines. EXAMPLE 4 shown inFIG. 11andFIG. 12will be described now in detail.

In EXAMPLES 1 to 3, it is necessary to use positive liquid crystal since molecular orientation7of liquid crystal and lateral electric field8are perpendicular (at 90 degrees) to each other. Meanwhile, in EXAMPLE 4, molecular orientation7liquid crystal of and lateral electric field8are in parallel to each other as shown inFIGS. 11 and 12, and thus there is a need to use a negative liquid crystal. The electrode structure as shown inFIG. 11andFIG. 12produces a very small amount of an electric field with a component in a direction perpendicular to the substrate surface. The negative liquid crystal in homogeneous alignment hardly causes deformation on such an electric field in the vertical direction. Therefore, since the negative liquid crystal in homogeneous alignment causes twist deformation with respect to the electric field in a direction parallel to the substrate surface, it becomes possible to obtain an IPS liquid crystal display device having an excellent viewing angle characteristics.

EXAMPLE 5 will be described now usingFIGS. 13 to 16.FIG. 13is a plan view illustrating a structure of one pixel of the liquid crystal display device according to EXAMPLE 5, where unit pixel27is indicated by an area surrounded by broken lines.FIG. 14is an enlarged view of columns and their circumference within a pixel inFIG. 13.FIG. 15andFIG. 16are plan views illustrating another structure of one pixel of the liquid crystal display device according to EXAMPLE 5, where unit pixel27is indicated by an area surrounded by broken lines. EXAMPLE 5 shown inFIGS. 13 to 16will be described now in detail.

Common electrode1is arranged so as to cover data lines5and scanning lines6, and the strip-shaped pixel electrode2is arranged in the central region of each pixel so as to extend along the extending direction of data lines5. The common electrode1includes a protruding region (part) arranged in the upper part of each pixel as shown inFIG. 13. Connected with strip-shaped pixel electrode2, second rectangular pixel electrode2ais arranged in the upper part of the pixel so as to extend or protrude outside the protruding common electrode1a. In each pixel, in a lower part of the pixel inFIG. 13, there is formed projecting-shaped pixel electrode2fwhich includes projection regions (projecting parts2g) each projecting from the corner part of opening section28of common electrode1. The projecting-shaped pixel electrode2fis connected to the strip-shaped pixel electrode2. As shown inFIGS. 13 and 14, the projecting-shaped pixel electrode2fand the strip-shaped pixel electrode2are connected at a position outside the opening section28of the common electrode1. By having such a structure, a part of the common electrode1covering the scanning line6and the strip-shaped pixel electrode2cross at substantial right angles, in the lower area of the pixel inFIG. 13. In the present example, the electrode for connecting the strip-shaped pixel electrode2and the projecting-shaped pixel electrode2ftogether is formed in a rectangular shape. However, its shape need not be a rectangle.

In the lateral-electric-field mode liquid crystal display device having such a structure, the situation of deformation of the liquid crystal in the upper part of the column is similar to the description of EXAMPLE 1. However, in the lower part of the column, there are lateral electric fields21aand21bin a region where the common electrode1and a projecting-shaped pixel electrode2fare close with each other, and fringe electric fields22aand22bproduced from the common electrode1and the projecting-shaped pixel electrode2f. The liquid crystal located in the left column is affected by the fringe electric field of22bso as to deform in the direction of i (from9ato9b). The lateral electric field21bis produced near the fringe electric field22b. However, since the lateral electric field21bis weak as compared to the fringe electric field22b, liquid crystal located in a region where the lateral electric field21bacts does not cause deformation in the direction of the lateral electric field21band deforms in the direction of i. Furthermore, in the lower part of the left column, the lateral electric field21ais produced in a region where the common electrode1and the strip-shaped pixel electrode2are close with each other. Such an electric field has an advantageous effect of strengthening the deformation of the liquid crystal in the left column in the direction of i. Similarly, the liquid crystal located in the right column is affected by the fringe electric field of22ato be deformed in the direction of ii (from9ato9b). The lateral electric field21ais produced near the fringe electric field22a. However, since the lateral electric field21ais weak as compared with the fringe electric field22a, the liquid crystal located in a region where the lateral electric field21aacts does not cause deformation in the direction of the lateral electric field21a, and deforms in the direction of ii. Furthermore, in the lower part of the right column, the lateral electric field21bis produced in a region where the common electrode1and the strip-shaped pixel electrode2are close with each other. Such an electrical field has an advantageous effect of further strengthening the deformation of the liquid crystal in the right column in the direction of ii.

The present example uses, in each pixel, projecting parts2geach of which projects inside opening section28from a corner part of the opening section28of common electrode1even if their projection amount is small, and the shape of the projecting part2gis not limited to a rectangular shape in particular. The present example has described a case where the projecting-shaped pixel electrode2fincludes recesses at both sides of the intersection part in the T shape. However, the projecting-shaped pixel electrode2fmay include only one recess at one side of the intersection part. Furthermore, as in EXAMPLE 2, the present example can be applied to a case (the case ofFIG. 5) where strip-shaped pixel electrodes2, projecting-shaped pixel electrodes2f, and second rectangular pixel electrodes2dare formed in a process forming the second metal layer in which data lines5are patterned. Further, as in EXAMPLE 3, the present example can be applied to a case that strip-shaped pixel electrodes2are formed to extend in the direction in parallel with the extending direction of scanning lines6, or a case as illustrated inFIGS. 15 and 16, that strip-shaped common electrode1bis arranged in the middle of plural (two inFIGS. 15 and 16) strip-shaped pixel electrodes2in each pixel, neighboring projecting pixel electrodes2fare connected to each other, and both end portions of strip-shaped common electrode1bare connected to common electrode1(this case can include the situation that a part of common electrode1covering data line5is hollowed out or the situation that is not hollowed out). Further, as in EXAMPLE 4, the present example can also be applied to a case that molecular orientation7of liquid crystal and lateral electric field8are parallel to each other (case ofFIG. 11orFIG. 12).

EXAMPLE 6 will be described now usingFIGS. 17, 18 and 19.FIG. 17is a plan view illustrating a structure of one pixel of the liquid crystal display device according to EXAMPLE 6 where unit pixel27is indicated by an area surrounded by broken lines).FIG. 18is a cross-sectional view taken along line XVIII-XVIII shown inFIG. 17and further illustrates a liquid crystal layer and opposing substrates.FIG. 19is an enlarged view of columns and their circumference in a pixel inFIG. 17. EXAMPLE 6 illustrated inFIG. 17,FIG. 18andFIG. 19will be described now in detail.

In EXAMPLE 1, since the pixel electrodes and the data lines5are formed in the same layer, there may be a short circuit due to a pattern collapse. In EXAMPLE 6, in order to suppress the short circuit between the pixel electrodes and the data lines5, the pixel electrodes are arranged in a layer above common electrode1, and transparent insulating film26is formed on common electrode1. Furthermore, a contact hole25is provided in passivation film13and transparent insulating film26to provide electrical conductivity between the strip-shaped pixel electrodes and the source electrode3in each pixel. Thereby, it is possible to suppress deterioration of the display image quality due to a short circuit between the pixel electrodes and the data lines5. Further, connected with strip-shaped pixel electrode2, rectangular pixel electrode2his arranged in the layer above common electrode1and in the lower part of the pixel inFIG. 17so as not to extend outside the common electrode1(toward the inside of the opening section28). Rectangular pixel electrode2hand source electrode3may be electrically connected via the contact hole25. In the upper part of the pixel ofFIG. 17, the strip-shaped pixel electrode2is arranged above the common electrode1so as to overlap with the common electrode1.

In a lateral-electric-field mode liquid crystal display device having such a structure, the situations of the deformation of the liquid crystal in the upper part of the column is such that, in the left column, a lateral electric field21bis produced so as to promote the deformation of the liquid crystal in the column in the direction of ii (from9ato9b), and in the right column, a lateral electric field21ais produced so as to promote the deformation of the liquid crystal in the column in the direction of i (from9ato9b). On the other hand, situations of deformation of the liquid crystal in the lower part of the column is such that, in the left column, a fringe electric field22ais produced so as to promote deformation of the liquid crystal in the column in the direction of ii, and in the right column, a fringe electric field22bis produced so as to promote deformation of the liquid crystal in the direction of i. Since the lateral electric field21aproduced near the fringe electric field22ais weak as compared to the fringe electric field22a, liquid crystal located in a region where the lateral electric field21aacts does not cause deformation in the direction of the lateral electric field21aand deforms in the direction of ii. Similarly, since the lateral electric field21bproduced near the fringe electric field22bis weak as compared to the fringe electric field22b, liquid crystal located in a region where the lateral electric field21bacts does not cause deformation in the direction of the lateral electric field21band deforms in the direction of i.

The manufacturing method of the liquid crystal display device of the present example is the same until the step of forming the thin film semiconductor layer4shown in EXAMPLE 1. Thereafter, source electrodes3and data lines5are formed of 300 nm thickness of layer of molybdenum alloy. After etching an unnecessary part of the n-a-Si layer of the thin film semiconductor layer4, 300 nm thickness of silicon nitride is deposited as a passivation film13.

Next, common electrode1is formed on the resulting structure. A transparent electrically-conductive film, such as an ITO (Indium Tin Oxide) film, is formed to be a thickness of 80 nm, and is patterned into a shape covering scanning lines6and data lines5.

Next, a transparent insulating film26is formed out of a silicon nitride film having a thickness of 300 nm. Thereafter, contact hole25is formed on the source electrode3into the passivation film13and the transparent insulating film26. At the same time, parts of gate insulating film12, passivation film13, and transparent insulating film26, which are necessary for exposing the metal layer on the terminal portions of the scanning line6and the data line5that have been led around the display screen, are removed by etching.

Next, a transparent electrically-conductive film, such as an ITO (Indium Tin Oxide) film, is formed and patterned into striped-shaped structures having a thickness of 300 nm and extending in a direction perpendicular to the extending direction of scanning lines6to form strip-shaped pixel electrodes2. In this process, rectangular pixel electrodes2hare formed at the same time. Further, the common electrode1is electrically-connected to the common-electrode line formed by the first metal layer and the second metal layer on the periphery of the display screen via a contact hole and the transparent electrically-conductive film being an upper layer. However, detailed illustrations in the drawings are omitted.

In present example, as described above, the pixel electrodes is located closer to the liquid crystal layer than common electrode1. In order to locate the pixel electrodes nearer to the liquid crystal layer, an insulating layer is formed between the pixel electrodes and the data lines5. Thus, a short circuit between the pixel electrodes and the data lines5due to a pattern collapse of the pixel electrodes or the data lines5can be prevented. In this example, strip-shaped pixel electrode2is formed in parallel with the extending direction of the data lines5in each pixel. However, it is also possible to form the strip-shaped pixel electrode2to extend in a direction in parallel with the extending direction of scanning lines6, as described in EXAMPLE 3. Alternatively, as described in EXAMPLE 4, the present example can also be applied to a case where molecular orientation7of liquid crystal and the lateral electric field8are parallel with each other (a case ofFIG. 11orFIG. 12).

Thought the present invention has been described with reference to each of the above-described embodiments, the present invention is not limited to them. The structures and details of the present invention can be modified in various ways that can be understood by one skilled in the art. As described above, the present invention is advantageous when the pixel size is small (in particular, when the pixel size, which is length of the long side of the pixel, is 100 μm or less). However, the present invention is not necessarily limited to this. Of course, this technique can be used as a measure against finger pressing marks even if the pixel size is comparatively large. In addition, embodiments obtained by combining a part or the entire structure of one of the above-described embodiments and examples and that of another of the above-described embodiments and examples as appropriate fall within the scope of the present invention.

The present invention is applicable to lateral-electric-field mode active matrix liquid crystal display devices and any apparatuses each using such a liquid crystal display device as a display device.