Array substrate and liquid crystal display device using the same

An array substrate including: a pixel defined by both a scanning line and a signal line intersecting with the scanning line, wherein a display area on a substrate includes a plurality of pixels arranged in a matrix shape, wherein the pixel includes: a switching device; a lower electrode that is connected to the switching device; an insulating film that is formed on the lower electrode; and an upper electrode that is formed on the insulating film to generate a fringe electric field between the lower electrode and the upper electrode, and wherein, in an area where the upper electrode is not formed and light is not transmitted, a contact hole is provided on a conducting pattern having the same potential as the lower electrode, by removing the insulating film.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2010-050537 filed on Mar. 8, 2010, the entire subject matter of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an array substrate and a liquid crystal display device. More specifically, the present invention relates to an array substrate in a fringe field switching (hereinafter also referred to as FFS) type and a configuration of a liquid crystal display device using the same.

Recently, instead of conventional cathode-ray tubes, new display apparatuses having a thin and flat display panel using such as liquid crystal, electroluminescence and charged particles, etc., is widely used. A liquid crystal display device, which is representative of the new display apparatuses, has not only a thin and lightweight but also low power consumption and low voltage driving characteristics. The liquid crystal display device has two substrates and the liquid crystal is sealed therebetween. One substrate is an array substrate having a display area in which a plurality of pixels is arranged in a matrix shape, and the other substrate is a counter substrate having a color filter, a black matrix (shielding plate), etc., formed thereto.

Superficially, in a thin film transistor (hereinafter also referred to as TFT) type liquid crystal apparatus, the TFT, which is a switching device, is provided in the respective pixels on the array substrate to maintain a voltage, which independently drives the liquid crystal of the respective pixels. Therefore, it is possible to display high-definition image having little crosstalk. Further, the respective pixels are provided with a scanning line (gate line), which controls of the TFTs state between ON and OFF, and a signal line (source line) intersecting with the scanning line to input image data. Generally, the respective pixels correspond to respective areas surrounded by the scanning line and the signal line.

In an in-plane switching (hereinafter referred to as IPS) liquid crystal display device, a plurality of pixel electrode and a plurality of counter electrode (common electrode) are alternately arranged at an interval on one array substrate, and an electric field is applied in a direction substantially horizontal to the substrate to display the image. The IPS type has a superior view angle and has an advantage over a typical twisted nematic (TN) type. However, the related IPS liquid crystal display device has a disadvantage that light transmittance is inferior to the typical TN type.

In order to solve the above problem, a fringe field switching (FFS) type has been considered (for example, see JP-A-11-202356, FIGS. 19 to 21). In the FFS type liquid crystal display device, a fringe electric field (oblique electric field including both components of a horizontal electric field and a vertical electric field) is applied to the liquid crystal to display the image. In the FFS liquid crystal display device, the pixel electrode and the counter electrode are formed on one array substrate, similar to the IPS type. However, the pixel electrode and the counter electrode are vertically arranged, and an insulating film is interposed therebetween. Typically, the lower electrode has a plate shape, and the upper electrode has a slit shape or a comb shape that have a gap part and a branch electrode part.

In the FFS type LCD, either the lower electrode or the upper electrode can be configured as the pixel electrode. Since the liquid crystal is driven by the fringe electric field between the upper electrode and the lower electrode in the FFS type LCD, the liquid crystal on the branch electrode part of the upper electrode can be also driven and be served to display. Thus, the light transmittance is improved in the FFS type LCD, compared to the IPS type LCD in which a part of the pixel electrode and the counter electrode scarcely serve to display.

SUMMARY

However, the related FFS type LCD has an asymmetric electrode configuration. In detail, except for an oriented film formed at an interface of the array substrate and the liquid crystal, the lower electrode is covered by an insulating film but the upper electrode is not covered by the insulating film. Accordingly, remnant charges are easily generated in the lower electrode covered by the insulating film. As a result, a screen burn-in phenomenon in which an afterimage is remained in the display is easily occurred.

Specifically, in case that the lower electrode is the pixel electrode, the lower electrode is separated by TFTs being the switching elements for each of the pixels, and the lower electrode is to be an electrically floating state when the TFT is turned off. Moreover, since the lower electrode is covered by the insulating film, the remnant charges are easily remained. Accordingly, the screen burn-in is easily occurred, compared to a configuration, in which the lower electrode is the counter electrode having a reference potential common to all pixels and the upper electrode is the pixel electrode.

A present invention made in consideration of the above problems. An object in an aspect of the present invention is to provide a configuration capable of suppressing the screen burn-in occurred in an FFS type array substrate, in which a lower electrode is a pixel electrode and an upper electrode is a counter electrode and a liquid crystal display device using the same.

An array substrate in an aspect of the present invention includes a pixel defined by both a scanning line and a signal line intersecting with the scanning line, wherein a display area on a substrate includes a plurality of pixels arranged in a matrix shape, wherein the pixel includes: a switching device; a lower electrode that is connected to the switching device; an insulating film that is formed on the lower electrode; and an upper electrode that is formed on the insulating film to generate a fringe electric field between the lower electrode and the upper electrode, and wherein, in an area where the upper electrode is not formed and light is not transmitted, a contact hole is provided on a conducting pattern having the same potential as the lower electrode, by removing the insulating film.

According to an aspect of the present invention, it is possible to achieve an FFS type array substrate and a liquid crystal display device having a configuration capable of suppressing screen burn-in.

DESCRIPTION OF PREFERRED ILLUSTRATIVE ASPECTS

Hereinafter, illustrative aspects of an array substrate and a liquid crystal display device in an aspect of the present invention will be described with reference to the drawings. In the respective drawings for describing each illustrative aspect, the same reference numerals indicate the same or equivalent parts. Thus, the repetitive descriptions will be omitted.

First Illustrative Aspect

First, a configuration of an array substrate and a liquid crystal display device in the present invention will be briefly described.FIG. 1is a plan view schematically showing an array substrate and a liquid crystal display device according to a first illustrative aspect.

A liquid crystal display device100has a display area50in which a plurality of pixels30is arranged in a matrix shape. In addition, the liquid crystal display device includes a liquid crystal cell that is made by bonding an array substrate10, and a counter substrate20. A scanning line, a signal line, a TFT, a pixel electrode (not shown), etc., are formed on the array substrate10. The counter substrate20faces the array substrate10with interposing the liquid crystal and includes a color filter and a black matrix, etc. A deflection plate and a phase plate (not shown) are adhered on both sides of the liquid crystal cell, and then a backlight, an external circuit, a housing (not shown), etc., are provided. Thus, the liquid crystal display device100is made up.

Meanwhile, the liquid crystal display device100includes a lead line of the scanning line or the signal line and an input line. The lead line extends from the display area50to output unit of the scanning line driving circuit60or the signal line driving circuit65, and the input line connects an input unit of each the scanning line driving circuit60and the signal line driving circuit65and a plurality of the terminal for the flexible substrates70and75that are provided to the end portion of the insulating substrate1. However, the lines are not shown to simplyFIG. 1.

In case that a small-sized panel, since the lines are relatively few, a driving circuit usually includes the scanning line driving circuit60and the signal line driving circuit65. At the same time, the flexible substrates70and75are usually bundled into one piece.

FIG. 2is an enlarged plan view of a pixel of an array substrate according to the first illustrative aspect.FIG. 3is a cross sectional view of the liquid crystal display device according to the first illustrative aspect, taken along a line A-A ofFIG. 2.

As shown inFIGS. 2 and 3, a scanning line2and a common line21formed at the same layer is provided on the insulating substrate1made of glass and plastic etc. The scanning line2is made of metal such as Al, Cr, Mo, Ti, Ta, W, Ni, Cu, Au, Ag, etc., or alloy or a stacked film thereof, and the a common line21is arranged in parallel to the scanning line and supplies a reference potential to an counter electrode.

Then, a gate insulating film3made of oxide film, nitride film, etc., is formed on an entire surface of the upper layer. A semiconductor film4and an ohmic contact film41doped impurities are stacked on a part of the gate insulating film3on the scanning line2.

Then, a signal line5, which is made of metal such as Al, Cr, Mo, Ti, Ta, W, Ni, Cu, Au, Ag, etc., or alloy or stacked film thereof, is formed on the gate insulating film3so as to intersect the scanning line2. In addition, a source electrode51and a drain electrode52provided at the same layer as the signal line5are formed to overlap with the ohmic contact film41. After that, the ohmic contact film41not overlapped by the source electrode51and the drain electrode52is removed. In other words, the ohmic contact film41between the source electrode51and the drain electrode52is removed, and a channel part of a TFT is formed. The scanning line2below the channel part also serves as a gate electrode. As a result, a TFT being a switching device is configured.

In the meantime, the semiconductor film4and the ohmic contact film41may be extended and be arranged along the signal line5not only in the TFT area.

A lower electrode6having a plate shape is a pixel electrode and is made of transparent conducting oxide film such as Indium Tin Oxide (hereinafter also referred as to ITO). In a reflection type LCD, the lower electrode may be formed by a conducting film having a high reflective surface and made of metal such as Al, Ag, Pt, etc., or alloy or a stacked film thereof. A part of the lower electrode6is overlapped on the drain electrode52and is electrically connected thereto. In the meantime, a part of the lower electrode6may be formed below the drain electrode52and may be electrically connected thereto.

A protecting film7, which is made of an oxide film, a nitride film, etc., an organic resin insulating film or a stacked film thereof, is formed at an upper layer of the signal line5, the TFT and the lower electrode6.

An upper electrode8made of a transparent conducting oxide film, such as ITO, is formed on the protecting film7. As shown inFIG. 2, the upper electrode8has a plurality of gap part81, in which transparent conducting oxide film is not provided, and a plurality of branch electrode part82that are electrically connected in common. In the first illustrative aspect, the upper electrode8has a slit shape that the gap parts81are surrounded by the transparent conducting oxide film. A fringe electric field is generated between the branch electrode part82and the lower electrode6exposed from the gap part81through the protecting film7. The liquid crystal15is driven by the fringe electric field. Herein and after, the word “expose” means that a part of one electrode is not covered by the protecting film7.

The upper electrode8is connected to the common line21via a contact hole9and serves as the counter electrode having a reference potential. Since the upper electrode8made of a transparent conducting oxide film has a specific resistance that is higher than that of the scanning line2or the signal line5made of a metal film, the upper electrode8is connected to the common line21formed at the same layer as the scanning line2for each pixel30for reducing the resistance. In the meantime, when the upper electrode8has a predetermined reference potential, it is not necessarily required to provide the contact hole9for each pixel30.

Although it is not shown, a terminal electrode is provided in an area of a terminal part for COG or a terminal part for the flexible substrate, and each terminal part is formed with a contact hole at the gate insulating film3or the protecting film7for electrical connection with the scanning line2or the signal line5. Typically, in order to improve corrosion-resistance, a transparent conducting oxide film formed at the same layer as the upper electrode8is formed on a surface of the terminal electrode.

The protecting film7for each pixel30includes not only than the contact hole9but also a second contact hole12, which is provided on a conducting pattern55having the same potential as the lower electrode6, in an area where the light is not transmitted by removing the insulating film. Further, the upper electrode8is not formed in an area the second contract hole12.

In the first illustrative aspect, the contact hole12is formed at a part of the lower electrode6of the pixel electrode extending and overlapping the scanning line2of the pixel30adjacent to up side or down side. When the lower electrode6in the area of the second contact hole12is made of the same transparent conducting oxide film, such as ITO, as the upper electrode8, it may be removed during an etching process of the upper electrode8. In order to avoid it, the lower electrode6in an area of the second contact hole12is stacked on the conducting pattern55, which is formed at the same layer as the signal line5and has the same potential as the second contact hole12. As a result, even when the lower electrode6in the area of the second contact hole12is removed during the etching process of the upper electrode8, it is possible to expose the conducting pattern55having the same potential as the lower electrode6through the second contact hole12.

In the meantime, when the lower electrode6in the area of the second contact hole12is not removed during the etching process of the upper electrode8, it is possible to utilize a part of the lower electrode6in the area of the second contact hole12as a conducting pattern having the same potential as the lower electrode6, so that it is not necessary to form the conducting pattern55formed at the same layer as the signal line5at the lower layer.

Since the second contact hole12is provided in an area of the scanning line2that does not serve to display, the reduction of the light transmittance due to the second contact hole12is not occurred.

In the first illustrative aspect, the upper electrode8of an counter electrode is connected to the upper electrode8of the adjacent pixels30through the connection parts85and86, which connects the each upper electrodes8at the same layer. The pixels are adjacent in the direction of the signal line5(up-down direction inFIG. 2) and the direction of the scanning line2(left-right direction inFIG. 2). A part of the scanning line2and the signal line5are covered by the connection parts85and86to form a lattice (mesh) shape. As a result, the resistance of the upper electrode8is further reduced.

By the lattice shape, even when the common line21is break and the reference potential is not supplied from the common line21to the upper electrode8through the contact hole9, the reference potential is supplied from the upper electrode8of the adjacent pixel30to the corresponding upper electrode8through the connection parts85and86. As a result, a display error is not prevented and the yield is improved.

In addition, the connection parts85and86cover the scanning line2or the signal line5, so that it is possible to block a leakage electric field from the scanning line2or the signal line5to the liquid crystal15. Accordingly, it is possible to suppress the display error due to the leakage electric field that is easy to be generated adjacent to the scanning line2or the signal line5.

In order to effectively block the leakage electric field from the scanning line2or the signal line5, a width of the conducting film of the connection parts85and86covering the scanning line2or the signal line5is preferably 2 micrometers or more larger than an edge of the scanning line2or the signal line5.

In addition, since the connection parts85and86have a function of a light shielding film, it may be possible to omit a black matrix along with the scanning line2or the signal line5from the counter substrate20having a color filter13, a back matrix, etc., formed on an insulating substrate11.

Additionally, the connection parts85and86may be connect to the upper electrode8of the adjacent pixel30only in one side of the signal line5direction (up-down direction) or the scanning line2direction (left-right direction).

In assembling the liquid crystal cell, after an oriented film14made of organic resin such as polyimide is applied, the array substrate10and the counter substrate20are performed by an orientation process using technologies of rubbing, optical orientation etc., so that liquid crystal molecules of the liquid crystal15are directed in a predetermined direction.

The array substrate10and the counter substrate20are stacked so that the oriented film14face to each other, and then the substrates are bonded by a seal material formed at the periphery of the display area50with an interval of about several micrometers formed by a spacer member. The liquid crystal15is sealed into the space of the inner side of the seal material.

After the deflection plate or the phase plate is adhered on both sides of the liquid crystal cell formed as described above, the scanning line driving circuit60, the signal line driving circuit65and the flexible substrate70and75are mounted. An external circuit for supplying various electric signals to the liquid crystal cell is mounted, and a backlight unit is provided a backside of the liquid crystal cells in a case transmission type, after that the material is provided to the housing. Thus, the liquid crystal display device100is made up.

Next, the effect in an aspect of the present invention will be described in detail. According to the first illustrative aspect, it is possible to achieve configuration in which the conducting pattern55having the same potential as the lower electrode6being the pixel electrode is exposed to the surface in the area of the second contact hole12on the array substrate10. In addition, the upper electrode8being the counter electrode is exposed to the surface.

As shown inFIG. 3, the liquid crystal display device100has the liquid crystal15that is sealed in the space between the array substrate10and the counter substrate20, and the respective interfaces of the array substrate10or counter substrate20and the liquid crystal15are formed with the oriented films14.

In the liquid crystal display device100, the electrical path (path of the electric field) between the lower electrode6being the pixel electrode and the lower electrode8being the counter electrode serve to display. In the area except for the second contact hole12, the electrical path passes the protecting film7, the oriented film14, the liquid crystal15and the oriented film14, in between the lower electrode6and the upper electrode8as shown with arrows L.

Accordingly, the electrical path between the lower electrode6and the upper electrode8passes the protecting film7and the oriented film14. In contrast, the electrical path between the upper electrode8and the liquid crystal15passes only the oriented film14. In other words, the lower electrode6and the upper electrode8have asymmetry regarding whether the protecting film7is exist in the electrical path to the liquid crystal15.

Generally, the liquid crystal display device100is driven by an alternating current driving method that is reversing polarities for each frame. However, when the asymmetry exists in the electrical path, a difference of the movement of charges between the lower electrode6and the upper electrode8is occurred. As a result, the remnant charges are easy to be generated in the lower electrode6that is at the lower layer of the protecting film7.

In contrast, when the second contact hole12is provided in the area that does not serve to display and does not transmit the light, similar to the first illustrative aspect, only the oriented film14exists in the electrical path between the conducting pattern55having the same potential as the lower electrode6and the liquid crystal15.

Since the lower electrode6is a conducting film, the remnant charges of the lower electrode6can easily move to the conducting pattern55in the area of the second contact hole12. That is, the area of the second contact hole12becomes an area having the same symmetry as the upper electrode8in the electrical path up to the liquid crystal15. Accordingly, a difference of the remnant charges between the lower electrode6and the upper electrode8is difficult to generate.

In the meantime, the oriented film14made of an organic resin is formed in the area of the second contact hole12and on the upper electrode8. However, since the oriented film is thin, such as from 50 to 200 nm, and has an n insulation property lower than that of the protecting film7, the remnant charges of the lower electrode8and the upper electrode9can easily move to the liquid crystal15via the oriented film14. As a result, the remnant charges are difficult to generate in the lower electrode6and the upper electrode8.

As described above, according to the array substrate10of the first illustrative aspect, in the area in which the upper electrode8is not formed and light is not transmitted, the second contact hole12, through which the conducting pattern55having the same potential as the lower electrode6is exposed, is provided in the protecting film7. Therefore, it is possible to suppress the problem caused by the remnant charges of the lower electrode6, in the FFS liquid crystal display device100in which the lower electrode6is used as the pixel electrode. Thus, the screen burn-in is reduced.

In addition, the second contact hole12is provided on the scanning line2, so that it is possible to prevent the reduction in the light transmittance due to the second contact hole12.

Second Illustrative Aspect

FIG. 4is an enlarged plan view of a pixel of an array substrate in a liquid crystal display device according to a second illustrative aspect.FIG. 5is a cross sectional view taken along a line B-B ofFIG. 4.

In the cross sectional views of the liquid crystal display device100of the second to sixth illustrative aspects, because the configurations of the oriented film14, the liquid crystal15and the counter substrate10are similar to the first illustrative aspect, the array substrate10is only shown.

According to the second illustrative aspect, the second contact hole12is formed on the conducting pattern55having the same potential as the lower electrode6formed at the same layer as the signal line5above the common line21formed at the same layer as the scanning line2. In addition, the upper electrode8is not formed in the area adjacent to the second contact hole12.

When the lower electrode6in the area of the contact hole12is not removed during the etching process of the upper electrode8, a part of the lower electrode6in the area of the contact hole12can be used as a conducting pattern having the same potential as the lower electrode7. Thus, it is not necessary to form the conducting pattern55formed at the same layer as the signal line5at the lower layer.

In addition, not similar to the first illustrative aspect, it is not necessary to overlap the lower electrode6being the pixel electrode with the scanning line2of the pixel30adjacent on the up side or down side. Therefore, an increase in the capacity of the scanning line2, which is due to the overlapping of the scanning line2and the lower electrode6, is prevented. As a result, it is possible to suppress an increase in the driving load of the scanning line2.

According to the second illustrative aspect, the second contact hole12, through which the conducting pattern55having the same potential as the lower electrode6being the pixel electrode is exposed, is provided above the common line21formed at the same layer as the scanning line2, in the protecting film7. Accordingly, it is possible to suppress the remnant charges of the lower electrode6. As a result, the screen burn-in is reduced, similar to the first illustrative aspect.

In addition, since a part of the common line21also does not serve to display and does not transmit the light, it is possible to prevent the reduction in the light transmittance due to the second contact hole12, similar to the first illustrative aspect.

Third Illustrative Aspect

FIG. 6is an enlarged plan view of a pixel of an array substrate in a liquid crystal display device according to a third illustrative aspect.FIG. 7is a cross sectional view taken along a line C-C ofFIG. 6.

According to the third illustrative aspect, the second contact hole12is provided in an area of the drain electrode52. InFIG. 6, the second contact hole12is formed to expose the drain electrode52, which is a conducting pattern having the same potential as the lower electrode6. In the meantime, when the lower electrode6in the area of the contact hole12is not removed during the etching process of the upper electrode8, a part of the lower electrode6on the drain electrode52may be used as a conducting pattern having the same potential as the lower electrode6.

According to the third illustrative aspect, the second contact hole12, through which the conducting pattern55having the same potential as the lower electrode6being the pixel electrode is exposed, is provided on the drain electrode52in the protecting film7. Accordingly, it is possible to suppress the remnant charges of the lower electrode6. As a result, the screen burn-in is reduced, similar to the first and second illustrative aspects.

In addition, since a part of the drain electrode52does not serve to the display and does not transmit the light, it is possible to prevent the reduction in the light transmittance due to the second contact hole12, similar to the first and second illustrative aspects.

Fourth Illustrative Aspect

FIG. 8is an enlarged plan view of a pixel of an array substrate in a liquid crystal display device according to a fourth illustrative aspect.FIG. 9is a cross sectional view taken along a line D-D ofFIG. 8.

The fourth illustrative aspect relates to improvement of the first illustrative aspect. According to the fourth illustrative aspect, an electrode pattern88is arranged adjacent to the area of the second contact hole12above the scanning line2of the pixel30adjacent on the up side and down side, and the electrode pattern88is connected to a conducting pattern (here, a part of the lower electrode6) having the same potential as the lower electrode6. The electrode pattern88has the same potential as the lower electrode6being the pixel electrode. Although the electrode pattern88is formed at the same layer as the upper electrode8, it is electrically separated from the upper electrode8.

According to the fourth illustrative aspect, since the second contact hole12is covered by the electrode pattern88formed at the same layer as the upper electrode8, the lower electrode6in the area of the second contact hole12is protected during the etching process of the upper electrode8. Accordingly, since it is possible to utilize the conducting pattern having the same potential as the lower electrode6as a part of the lower electrode6, it is not necessary to provide the conducting pattern55having the same potential as the lower electrode6at the lower layer of the lower electrode6, similar the first illustrative aspect.

Accordingly, the electrode pattern88is formed adjacent to the area of the second contact hole12, so that it is possible to configure a surface area of the electrode pattern88greater than an opening area of the second contact hole12through which the conducting pattern having the same potential as the lower electrode6is exposed. Accordingly, since it is possible to increase a square measure of an interface between the electrode pattern88having the same potential as the lower electrode6and the liquid crystal15. Accordingly, the remnant charges of the lower electrode6can move to the liquid crystal15more easily than the first illustrative aspect.

In addition, the electrode pattern88is formed on the same surface as the upper electrode8close to the interface with the liquid crystal14. Accordingly, even when the film thickness of the oriented film14is higher than the top of the upper electrode8in the second contact hole12, since the electrode pattern88is exposed to the same surface as the upper electrode8, it is possible to effectively reduce the remnant charges of the lower electrode6. Therefore, it is possible to reduce the screen burn-in more effectively than the first illustrative aspect.

Fifth Illustrative Aspect

FIG. 10is an enlarged plan view of a pixel of an array substrate in a liquid crystal display device according to a fifth illustrative aspect.FIG. 11is a cross sectional view taken along a line E-E ofFIG. 10.

The fifth illustrative aspect relates to improvement of the second illustrative aspect. According to the fifth illustrative aspect, the electrode pattern88is arranged adjacent to the area of the second contact hole12above the common line21of the reference potential arranged parallel to the scanning line2, and the electrode pattern88is connected to a conducting pattern (here, a part of the lower electrode6) having the same potential as the lower electrode6. Thus, the electrode pattern88has the same potential as the lower electrode6being the pixel electrode. Although the electrode pattern88is formed at the same layer as the upper electrode8, it is electrically separated from the upper electrode8.

According to the fifth illustrative aspect, since the second contact hole12is covered by the electrode pattern88formed at the same layer as the upper electrode8, the lower electrode6in the area of the second contact hole12is protected during the etching process of the upper electrode8. Accordingly, since it is possible to utilize the conducting pattern having the same potential as the lower electrode6as a part of the lower electrode6, it is not necessary to provide the conducting pattern55having the same potential as the lower electrode6at the lower layer of the lower electrode6, like the second illustrative aspect.

Accordingly, the electrode pattern88is formed adjacent to the area of the second contact hole12, so that it is possible to configure a surface area of the electrode pattern88greater than an opening area of the second contact hole12through which the lower electrode6is exposed. Accordingly, since it is possible to increase an square measure of an interface between the electrode pattern88having the same potential as the lower electrode6and the liquid crystal15, the remnant charges of the lower electrode6can move to the liquid crystal15more easily than the second illustrative aspect.

In addition, the electrode pattern88is formed on the same surface as the upper electrode8close to the interface with the liquid crystal14. Accordingly, even when the film thickness of the oriented film14is higher than the top of the upper electrode8in the second contact hole12, since the electrode pattern88is exposed to the same surface as the upper electrode8, it is possible to effectively reduce the remnant charges of the lower electrode6. Therefore, it is possible to reduce the screen burn-in more effectively than the second illustrative aspect.

Sixth Illustrative Aspect

FIG. 12is an enlarged plan view of a pixel of an array substrate in a liquid crystal display device according to a sixth illustrative aspect.FIG. 13is a cross sectional view taken along a line F-F ofFIG. 13.

The sixth illustrative aspect relates to improvement of the third illustrative aspect. According to the sixth illustrative aspect, the second contact hole12is formed on the drain electrode52and the electrode pattern88is arranged adjacent to the area of the second contact hole12and is connected to a part of the lower electrode6stacked on the drain electrode52. The electrode pattern88has the same potential as the lower electrode6being the pixel electrode. Although the electrode pattern88is formed at the same layer as the upper electrode8, it is electrically separated from the upper electrode8.

According to the sixth illustrative aspect, since the second contact hole12is covered by the electrode pattern88formed at the same layer as the upper electrode8, the lower electrode6in the area of the second contact hole12is protected during the etching process of the upper electrode8. The conducting pattern having the same potential as the lower electrode6exposed through the second contact hole12may be either a part of the lower electrode6or the drain electrode52.

Accordingly, the electrode pattern88is formed adjacent to the area of the second contact hole12, so that it is possible to configure a surface area of the electrode pattern88greater than an opening area of the second contact hole12through which the lower electrode6is exposed. Accordingly, since it is possible to increase an square measure of an interface between the electrode pattern88having the same potential as the lower electrode6and the liquid crystal15, the remnant charges of the lower electrode6can move to the liquid crystal15more easily than the third illustrative aspect.

In addition, the electrode pattern88is formed on the same surface as the upper electrode8close to the interface with the liquid crystal14. Accordingly, even when the film thickness of the oriented film14is higher than the top of the upper electrode8in the second contact hole12, since the electrode pattern88is exposed to the same surface as the upper electrode8, it is possible to effectively reduce the remnant charges of the lower electrode6. Therefore, it is possible to reduce the screen burn-in more effectively than the third illustrative aspect.

In the above illustrative aspects, the TFT of a channel etched inverted staggered type has been exemplified. However, an aspect of the present invention can be also applied to an FFS array substrate, in which a TFT of an etch-stopper inverted staggered type, a top gate type, etc., is used, and a liquid crystal display device using the same.

In the above illustrative aspects, the driving circuits are mounted by the COG mount technology. However, an aspect of the present invention can be also applied to an FFS array substrate, in which the driving circuits are mounted a Tape Automated Bonding (TAB) mount technology or in which the driving circuits are embedded and formed on the array substrate by TFTs, and a liquid crystal display devices using the same.