Liquid crystal display device

According to one embodiment, a liquid crystal display device comprises first and second substrates, a sealing member, and a liquid crystal layer. The first substrate includes an image display area, a peripheral area, a common electrode, a scanning line, a signal line, a switching element, a pixel electrode, and first and second electrodes. At least a part of the first electrode is formed of a metal material and is closer to the liquid crystal layer than the scanning and signal lines. The first voltage is applied to the first electrode and the second voltage is applied to the second electrode. Ions in the liquid crystal layer are trapped by an electric field formed between the first and second electrodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-161449, filed Aug. 24, 2017, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystal display device.

BACKGROUND

A liquid crystal display panel including a first substrate, a second substrate, and a liquid crystal layer interposed between these substrates is known. Ions resulting from impurities or ions eluted from a sealing member which sticks the first substrate and the second substrate to each other often enter the liquid crystal layer. If the ion density becomes locally high in the liquid crystal layer, the effective voltage applied to the liquid crystal layer at this part may be lowered. In accordance with this, the luminance at the part may be lowered and a display image may be affected by black non-uniformity in display or the like.

A technology of disposing an electrode in a peripheral area outside the display area and trapping ions by the electrode to prevent the degradation in display quality in a display area has been proposed. Further improvement in the display quality and reliability has been required for such a liquid crystal display device comprising the electrode for trapping the ions.

DETAILED DESCRIPTION

In general, according to one embodiment, a liquid crystal display device comprises a first substrate, a second substrate, a sealing member, and a liquid crystal layer. The first substrate includes an image display area, a peripheral area outside the display area, a common electrode in the display area, a scanning line extending in the display area, a signal line which extends in the display area and intersects the scanning line, a switching element driven by the scanning line and the signal line, a pixel electrode opposed to the common electrode and connected to the switching element, and a first electrode and a second electrode in the peripheral area. The second substrate is opposed to the first substrate. The sealing member sticks the first substrate and the second substrate to each other. The liquid crystal layer is in a space surrounded by the first substrate, the second substrate, and the sealing member. At least a part of the first electrode is formed of a metal material having a light shielding property and is disposed at a position closer to the liquid crystal layer than the scanning line and the signal line. The first voltage is applied to the first electrode. The second voltage larger than the first voltage is applied to the second electrode. Ions existing in the liquid crystal layer are trapped by an electric field formed between the first electrode and the second electrode.

According to this configuration, degradation in display quality caused by the ions in the liquid crystal layer can be prevented and the reliability of the display device can be increased.

Some embodiments will be described hereinafter with reference to the accompanying drawings. The disclosure is merely an example, and proper changes within the spirit of the invention, which are easily conceivable by a skilled person, are included in the scope of the present invention as a matter of course. In addition, in some cases, in order to make the description clearer, the drawings may be more schematic than in the actual modes, but they are mere examples, and do not limit the interpretation of the present invention. In the drawings, reference numbers of continuously arranged elements equivalent or similar to each other are omitted in some cases. In the specification and the drawings, structural elements performing the same functions as or similar functions to those already described will be given the same reference numbers, and overlapping detailed descriptions may be omitted.

In the present embodiment, a liquid crystal display device is described as an example of the display device. However, each embodiment does not prevent application of individual technical ideas disclosed in the embodiment to the other types of display devices.

FIG. 1is a plan view schematically showing a liquid crystal display device1(hereinafter referred to as display device1) according to a first embodiment. The display device1comprises a display panel PNL and a controller2. For example, the display device1is a transmissive display device which comprises a backlight opposed to the back surface of the display panel PNL and uses the light from the backlight for image display. As the other example, the display device1may be a reflective display device which reflects light such as external light supplied from a front surface of the display panel PNL and uses the reflected light for image display.

The display panel PNL comprises a first substrate SUB1, a second substrate SUB2, a sealing member SL, and a liquid crystal layer LC. The first substrate SUB1and the second substrate SUB2are opposed to each other. The sealing member SL is disposed in a frame shape along an edge portion of the display panel PNL, between the first substrate SUB1and the second substrate SUB2to stick the first substrate SUB1and the second substrate SUB2on each other. The liquid crystal layer LC is disposed in space surrounded by the first substrate SUB1, the second substrate SUB2, and the sealing member SL.

As shown in the drawing, the first direction X, the second direction Y, and the third direction Z will be defined. The directions X, Y, and Z are orthogonal to each other in the present embodiment, but may intersect at an angle other than 90 degrees. In the present disclosure, a direction from the first substrate SUB1to the second substrate SUB2is referred to as “above” or “over”, and an opposite direction is referred to as “under” or “below”.

The display panel PNL includes a display area DA on which an image is displayed, and a peripheral area SA located outside the display area DA. The peripheral area SA includes a terminal area TA where the first substrate SUB1is exposed from the second substrate SUB2.

The first substrate SUB1comprises scanning lines G and signal lines S extending in the display area DA. The scanning lines G extend in the first direction X and are arranged in the second direction Y. The signal lines S extend in the second direction Y and are arranged in the first direction X. In the example shown inFIG. 1, an area sectioned by two scanning lines G and two signal lines S corresponds to a sub-pixel SP. One pixel PX is composed of sub-pixels SP of different colors. For example, the pixel PX includes red, green, and blue sub-pixels SP. The pixel PX is not limited to this, but may have the other configuration including a white sub-pixel SP or the like.

The first substrate SUB1comprises switching elements SW and pixel electrodes PE which are provided for each sub-pixel SP, and common electrodes CE each provided for the sub-pixels SP. The switching element SW is driven by the scanning line G and the signal line S. The pixel electrode PE is connected to the switching element SW.

The first substrate SUB1comprises scanning line drivers GD1and GD2, and a signal line driver SD. The scanning line drivers GD1and GD2supply scanning signals to the scanning lines G. The signal line driver SD supplies video signals to the signal lines S. In the example shown inFIG. 1, the scanning lines G are alternately connected to the scanning line drivers GD1and GD2. In the other example, the first substrate SUB1may comprise either the scanning line driver GD1or the scanning line driver GD2, and all of the scanning lines G may be connected to the scanning line driver.

The controller2is, for example, an IC and is mounted in the terminal area TA. The controller2controls the scanning line drivers GD1and GD2, and the signal line driver SD. A terminal T for external connection is provided in the terminal area TA. For example, a flexible printed circuit is connected to the terminal T. The controller2may be mounted on, for example, a member different from the terminal area TA such as the flexible printed circuit.

FIG. 2is a plan view schematically showing a structure of a sub-pixel SP. Several elements provided on the first substrate SUB1are illustrated and the illustration of the switching elements SW is omitted.

In the example shown inFIG. 2, the signal lines S extend in the second direction Y while bending. The signal lines S may extend straight in the second direction Y. The Each pixel electrode PE is disposed above the common electrode CE and includes two slits ST. The pixel electrode PE may include one or three or more slits ST or may include no slits ST. Each of the common electrodes CE is disposed between adjacent scanning lines G and opposed to the pixel electrodes PE. The common electrodes CE may overlap the scanning lines G and be provided sequentially along the sub-pixels SP which are arranged in the second direction Y.

The first substrate SUB1comprises metal lines ML. The metal lines ML are disposed above corresponding signal lines S and overlap the signal lines S in planar view. The metal lines ML are electrically connected to the common electrodes CE. The common electrodes CE arranged in the second direction Y are electrically connected by the metal lines ML.

FIG. 3is a cross-sectional view schematically showing the display panel PNL seen along line inFIG. 2. The first substrate SUB1comprises a first insulating base10, a first insulating layer11, a second insulating layer12, a third insulating layer13, a first alignment film14, the signal lines S, the common electrode CE, the pixel electrode PE, and the metal lines ML. The first substrate SUB1also comprises the scanning lines G, a semiconductor layer of the switching elements SW, and the like.

The first insulating base10is, for example, a glass substrate but may be a flexible resin substrate. The first insulating layer11covers the first insulating base10. The signal line S is also disposed on the first insulating layer11. InFIG. 3, the first insulating layer11is a single layer but is actually composed of plural layers. The plural layers include an insulating layer which separates the semiconductor layer of the switching element SW from the scanning lines G, and an insulating layer which separates the scanning lines G or the semiconductor layer from the signal lines S.

The second insulating layer12covers the first insulating layer11and the signal lines S. The second insulating layer12is formed of, for example, an organic resin material and is thicker than the first insulating layer11and the third insulating layer13. The common electrode CE covers the second insulating layer12. The metal line ML is disposed on the common electrode CE. The third insulating layer13covers the common electrode CE and the metal lines ML. The pixel electrodes PE are formed on the third insulating layer13. The first alignment film14covers the third insulating layer13and the pixel electrodes PE.

The metal lines ML may be disposed between the second insulating layer12and the common electrode CE. In addition, an insulating layer may be interposed between the metal lines ML and the common electrodes CE, and the metal lines ML and the common electrodes CE may be electrically connected through a contact hole formed in the insulating layer.

The second substrate SUB2comprises a second insulating substrate20, a light-shielding layer21, a color filter22, an overcoat layer23, and a second alignment film24. The second insulating base20is, for example, a glass substrate but may be a flexible resin substrate.

The light-shielding layer21is disposed under the first insulating base20. The light-shielding layer21overlaps the metal lines ML, the signal lines S, and the scanning lines G in planar view. The color filter22is colored in a color corresponding to the sub-pixel SP and disposed under the second insulating base20. For example, a boundary between the color filters22having different colors overlaps the light-shielding layer21in planar view. The overcoat layer23covers the color filter22. The second alignment film24covers the overcoat layer23. The liquid crystal layer LC is disposed between the first alignment film14and the second alignment film24.

The pixel electrodes PE and the common electrodes CE can be formed of, for example, a transparent conductive material such as indium tin oxide (ITO). The gate lines G, the source lines S, and the metal lines ML can be formed of various metal materials having a light shielding property. The gate lines G, the source lines S, and the metal lines ML may be formed in a single-layer structure or a multilayer structure. Each layer of the gate lines G, the source lines S, and the metal lines ML may be formed of a metal alone or an alloy.

The structure of the display panel PNL shown inFIG. 3corresponds to Fringe Field Switching (FFS) mode, which is one of In-Plane Switching (IPS) modes. The structure of the display panel PNL is not limited to this but, for example, the common electrode CE may be disposed at a position closer to the liquid crystal layer LC than the pixel electrode PE. In addition, the display panel PNL may comprise a structure conforming to various modes such as Vertical Aligned (VA) mode and Twisted Nematic (TN) mode.

In the display device1configured as explained above, ions resulting from impurities of water or the like immersing from the outside or ions eluting from the sealing member SL, the first alignment film14, and the second alignment film24may enter the liquid crystal layer LC. In this case, if such ions are collected in the display area DA, an effective voltage between the pixel electrodes PE and the common electrodes CE is lowered and an influence such as black non-uniformity in display may appear on the display image. The display device1according to the present embodiment desirably comprises an ion trap structure capable of allowing such ions to stay in the peripheral area SA.

FIG. 4is a plan view of the display panel PNL, schematically showing an example of the ion trap structure. In the present embodiment, the display panel PNL is shaped in a rectangle having edges E11to E14. The edges E11and E12are parallel to the second direction Y, and the edges E13and E14are parallel to the first direction X. The edge E14is an edge on the terminal area TA side.

In addition, the display area DA is shaped in a rectangle having edges E21to E24. The edges E21and E22are parallel to the second direction Y, and the edges E23and E24are parallel to the first direction X. The edge E24is an edge on the terminal area TA side.

The shape of the display panel PNL and the display area DA is not limited to a rectangle, but may be a polygon other than a square or curved at least in part.

The first substrate SUB1comprises a first electrode EL1and a second electrode EL2in the peripheral area SA. The first electrode EL1extends linearly between the edges E11and E21, between the edges E13and E23, and between the edges E12and E22. The first electrode EL1may include a portion extending in a curved shape. In addition, plural first electrodes EL1may be intermittently disposed in the peripheral area SA.

The second electrode EL2includes an outer portion EL2a, an inner portion EL2bdisposed between the outer portion EL2aand the display area DA, and connection portions CP1and CP2which connect the outer portion EL2aand the inner portion EL2b. The outer portion EL2aand the inner portion EL2bextend linearly between the edges E11and E21, between the edges E12and E22, and between the edges E13and E23. The outer portion EL2aand the inner portion EL2bmay include portions extending in a curved shape. The first electrode EL1is disposed between the outer portion EL2aand the inner portion EL2b. The connection portions CP1and CP2connect end portions of the outer portion EL2aand the inner portion EL2bon the edge E14side.

In the example shown inFIG. 4, neither the first electrode EL1nor the second electrode EL2is disposed between the edges E14and E24. However, the first electrode EL1and the second electrode EL2may be disposed between the edges E14and E24. In addition, the first electrode EL1and the second electrode EL2do not need to be disposed in the whole area between the edges between the edges E11and E21, between the edges E12and E22, and between the edges E13and E23, but the first electrode EL1and the second electrode EL2may be partially disposed in this area. For example, the first electrode EL1and the second electrode EL2may be disposed near a corner C1formed by the edges E21and E23, and near a corner C2formed by the edges E22and E23.

A first voltage VL is applied to the first electrode EL1. A second voltage V0larger than the first voltage is applied to the second electrode EL2. For example, the first voltage VL is −7V, and the second voltage V0is the common voltage (0V) which is the same as the voltage applied to the common electrodes CE. In this case, for example, an electric field having a strength of 0.28 V/μm is generated between the first electrode EL1and the second electrode EL2. Plus ions in the liquid crystal layer LC are trapped into the first electrode EL1by the electric field.

FIG. 5is a cross-sectional view schematically showing the display panel PNL seen along line V-V inFIG. 4. The first electrode EL1is disposed on the second insulating layer12, and covered with the third insulating layer13. As the other example, the first electrode EL1may not be covered with the third insulating layer13.

Both of the outer portion EL2aand the inner portion EL2bof the second electrode EL2are disposed on the third insulating layer13. In the example shown inFIG. 5, the outer portion EL2ais covered with the sealing member SL while the inner portion EL2bis covered with the first alignment film14. The sealing member SL is not disposed above the first electrode EL1. As the other example, the sealing member SL may be disposed above the first electrode EL1.

A first line L1is disposed under the first electrode EL1. The above-mentioned scanning line driver GD1is disposed under the outer portion EL2a. A second line L2and a third line L3are disposed under the inner portion EL2b. The first line L1and the second line L2are disposed on the first insulating layer11, and covered with the second insulating layer12. The third line L3is disposed on the second insulating layer12, and covered with the third insulating layer13.

The first electrode EL1is located at a position closer to the liquid crystal layer LC than the scanning lines G and the signal lines S. More specifically, the first electrode EL1is disposed in the same layer as the metal line ML and is formed of the same metal material having a light shielding property as the metal line ML. In other words, the first electrode EL1can be formed in the same process as the metal line ML. The first electrode EL1and the metal line ML can be formed to have, for example, a multilayer structure in which an aluminum layer is sandwiched between molybdenum layers. As the other example, tungsten, copper, titanium, and the like can be used as the metal material of the first electrode EL1and the metal line ML.

The second electrode EL2is disposed in the same layer as the pixel electrode PE and formed of the same transparent conductive material as the pixel electrode PE. In other words, the second electrode EL2can be formed in the same process as the pixel electrode PE.

The first line L1and the second line L2are disposed in the same layer as the signal line S and formed of the same metal material as the signal line S. In other words, the first line L1and the second line L2can be formed in the same process as the signal line S. The third line L3is disposed in the same layer as the common electrode CE and formed of the same transparent conductive material as the common electrode CE. In other words, the third line L3can be formed in the same process as the common electrode CE.

The scanning line driver GD1is composed of metal lines, a semiconductor layer, and the like disposed in the same layer as the scanning line G and the signal line S. The outer portion EL2aoverlaps the scanning line driver GD1in planar view. The outer portion EL2aplays a role as a shield which blocks the electric field from the scanning line driver GD1.

As shown in the drawing, a width of the first electrode EL1is defined as W1, a width of the outer portion EL2ais defined as W2, a width of the inner portion EL2bis defined as W3, a width of the first line L1is defined as W4, a gap between the first electrode EL1and the outer portion EL2ais defined as G1, and a gap between the first electrode EL1and the inner portion EL2bis defined as G2.

In the present embodiment, the width W1is smaller than the width W2, and the width W1is larger than the width W3(W3<W1<W2). For example, the width W1is 20 μm, the width W2is 240 μm, and the width W3is 8 μm.

In addition, in the present embodiment, the gap G1is smaller than the gap G2(G1<G2). For example, the gap G1is 25 μm and the gap G2is 46 μm.

In addition, in the present embodiment, the width W4is larger than the width W1. In other words, the first line L1includes an opposed portion L1awhich is opposed to the first electrode EL1, and unopposed portions L1band L1cthat are unopposed to the first electrode EL1. The unopposed portion L1bis an area extending from the first electrode EL1toward the outer portion EL2aside, and the unopposed portion L1cis an area extending from the first electrode EL1toward the inner portion EL2bside. The opposed portion L1aand the unopposed portions L1band L1cextend along the first electrode EL1shown inFIG. 4. A width of each of the unopposed portions L1band L1cis smaller than or equal to the width W1. For example, the width of each of the unopposed portions L1band L1cis 5 μm.

The above-mentioned first voltage VL is applied to the first electrode EL1and the first line L1. The above-mentioned second voltage V0is applied to the outer portion EL2a, the inner portion EL2b, the second line L2, and the third line L3. In this case, electric fields for ion trap are generated between the first electrode EL1and the outer portion EL2a, and between the first electrode EL1and the inner portion EL2b, as represented by broken curved lines inFIG. 5. In addition, electric fields for ion trap are also generated between the unopposed portion L1band the outer portion EL2a, and between the unopposed portion L1cand the inner portion EL2b. Thus, in the example shown inFIG. 5, the electric fields for ion trap can be formed separately between the first electrode EL1and the second electrode EL2, and between the first line L1and the second electrode EL2.

A thickness of the first electrode EL1is larger than a thickness of the second electrode EL2(thickness of each of the portions EL2aand EL2b). The thickness of the first electrode EL1can be set to be twice or more as large as the thickness of the second electrode EL2. For example, the thickness of the first electrode EL1is 100 μm while the thickness of the second electrode EL2is 40 μm. For example, the thickness of the first electrode EL1is substantially the same as the thickness of the third insulating layer13.

A protrusion PT resulting from the first electrode EL1is generated on the upper surface of the third insulating layer13. A height of the protrusion PT is the same as, for example, the thickness of the first electrode EL1. The first alignment film14can be formed by, for example, applying an alignment film material on the first alignment film13by a printing method or the like and then curing the alignment film material. The protrusion PT functions as a stopper which blocks the alignment film material to be cured.

In the example shown inFIG. 5, the first alignment film14therefore does not exist between the protrusion PT (or the first electrode EL1) and the edge E11. Therefore, since the first alignment film14does not exist under the sealing member SL, adherence between the sealing member SL and the first substrate SUB1is enhanced.

The first alignment film14may exist between the protrusion PT and the edge E11. In this case, too, since the alignment film material to be cured is somewhat blocked by the protrusion PT, the thickness of the first alignment film14between the first electrode EL1and the edge E11is smaller than the thickness of the first alignment film14between the first electrode EL1and the display area DA (right side in the drawing).

The structures between the edges E12and E22, and between the edges E13and E23are the same as that shown inFIG. 5, and their explanations are omitted.

FIG. 6is an enlarged plan view showing a vicinity to a connection portion CP1shown inFIG. 4. The first electrode EL1and the first line L1are electrically connected via a first connection structure CM1. The second electrode EL2and the lines L2and L3are electrically connected via a second connection structure CM2.

The first connection structure CM1comprises two contact holes H11and a relay electrode RE. The second connection structure CM2comprises two contact holes H21and a contact hole H22. The contact holes H11and H21penetrate the second insulating layer12. The contact hole H22penetrates the third insulating layer13.

The replay electrode RE is disposed on the second insulating layer12. The relay electrode RE is disposed in the same layer as the common electrode CE and formed of the same transparent conductive material as the common electrode CE. In other words, the relay electrode RE can be formed in the same process as the common electrode CE. The relay electrode RE is in contact with the first line L1through the contact holes H11. Furthermore, the relay electrode RE is covered with the first electrode EL1. The first electrode EL1and the first line L1are thus electrically connected to each other.

The third line L3is in contact with the second line L2through the contact holes H21. The second electrode EL2is in contact with the third line L3through the contact hole H22. The second electrode EL2and the lines L1and L3are thus electrically connected to each other.

The above-mentioned controller2supplies the first voltage VL to the first line L1, and supplies the second voltage V0to the second line L2and the third line L3.

The first connection structure CM1and the second connection structure CM2are also provided near the connection portion CP2shown inFIG. 4. The positions where the first connection structure CM1and the second connection structure CM2are provided are not limited to two positions but may be more positions.

Next, an advantage of the present embodiment will be explained with a comparative example inFIG. 7. In this comparative example, the first electrode EL1is formed of ITO of the same layer as the second electrode EL2(portions EL2aand EL2b).

If the first voltage VL is applied to the first electrode EL1, positive ions in the liquid crystal layer LC are drawn toward the first electrode EL1. If the first voltage VL is applied to the first electrode EL1for a long time, In2O3contained in ITO is corroded (reduced) by positive ions, and O2gas and lower oxide InOx are generated. Air bubbles of O2gas are generated and accumulated, for example, between the first alignment film13and the first alignment film14and in the liquid crystal layer LC, which is one of reasons for degradation in reliability of the display device. In addition, the first electrode EL1is whitened by lower oxide InOx.

In the configuration of the comparative example, it was found by experiments that corrosion of the first electrode EL1hardly occurs as the gaps G1and G2are made sufficient large. However, if the gaps G1and G2are made larger, narrowing the frame of the display device becomes difficult since the width of the peripheral area SA is larger.

In addition, in the configuration of the comparative example, the alignment film material can hardly be blocked in the formation of the first alignment film14since the first electrode EL1is thin. The first alignment film14can be therefore formed to extend up to a lower side of the sealing member SL.

In contrast, in the structure of the present embodiment shown inFIG. 5, the first electrode EL1is formed of the same metal material as the metal line ML. As explained above, the metal line ML can be formed of aluminum, molybdenum, tungsten, copper, titanium, or the like, and these metal materials are materials which can hardly be reduced as compared with ITO. Therefore, corrosion (reduction) of the first electrode EL1can be suppressed and the reliability of the display device1can be increased.

Since the corrosion of the first electrode EL1is thus suppressed, the gaps G1and G2can be made smaller. Since the width of the peripheral area SA is thereby made smaller, the frame of the display device1can be narrowed.

In addition, the alignment film material can be blocked by the protrusion PT as explained above. Therefore, the adherence of the sealing member SL can be enhanced and the reliability of the display device1can be further increased.

In addition to the above, various suitable advantages can be obtained from the present embodiment.

A second embodiment will be described. Explanations of the same constituent elements and advantages as the first embodiment will be omitted.

FIG. 8is a plan view schematically showing a display device1according to the second embodiment. An example of an ion trap structure is shown similarly toFIG. 4. In the present embodiment, a first electrode EL1includes a first portion EL1aformed of a metal material and a second portion EL1bformed of a transparent conductive material.

In the example shown inFIG. 8, the first portions EL1aare disposed near a corner C1formed by the edges E21and E23, and near a corner C2formed by the edges E22and E23, respectively. In addition, the second portions EL1bare disposed between edges E11and E21, between edges E12and E22, and between edges E13and E23, respectively.

Two first portions EL1aare bent at right angles along corners C1and C2, respectively. The first portions EL1amay be bent in a slightly arcuate shape along corners C1and C2, respectively. Three second portions EL1aextend linearly along the edges E21, E22, and E23, respectively. Two first portions EL1aand three second portions EL1bare connected at their ends, and entirely form the same shape as the first electrode EL1shown inFIG. 4.

A sectional structure of a peripheral area SA including the first portions EL1ais the same as that shown inFIG. 5.

In addition, a sectional structure of a peripheral area SA including the second portions EL1bis the same as that in the comparative example shown inFIG. 7. The sectional structure of the peripheral area SA including the second portions EL1bmay be the same as that in the modified example shown inFIG. 9.

In this modified example, a fourth line L4is disposed below the second portion EL1b. The fourth line L4is disposed on a second insulating layer12, and covered with a third insulating layer13. The fourth line L4is disposed in the same layer as a metal line ML and is formed of the same metal material as the metal line ML. In other words, the first electrode EL1can be formed in the same process as the metal line ML.

A protrusion PT2resulting from the fourth line L4is generated on the upper surface of the third insulating layer13. The second portion EL2bis disposed on the protrusion PT2. An alignment film material to be cured can be blocked by the protrusion PT2in the formation of a first alignment film14.

FIG. 10is a plan view schematically showing a vicinity to a boundary between the first portion EL1aand the second portion EL1b. The first portion EL1aand the second portion EL1bare in contact with two contact holes H that penetrate the third insulating layer13. The first portion EL1aand the second portion EL1bare thereby electrically connected to each other. The number of the contact holes H is not limited to two but may be one or three or more.

In the above-explained embodiment, the second portion EL1bis located at a position closer to the liquid crystal layer LC than the first portion EL1a. Therefore, since an electric field formed between the second portion EL1band the second electrode EL2can easily act on the liquid crystal layer LC, the ion trap ability can be enhanced.

Ions in the liquid crystal layer LC can easily be collected at positions close to the corners C1and C2. Therefore, the above-explained corrosion (reduction) occurs mainly at the positions close to the corners C1and C2. The corrosion can be prevented similarly to the first embodiment, by forming the first electrode EL1of the metal material at the only positions close to the corners C1and C2similarly to the present embodiment.

All of the display devices that can be implemented by a person of ordinary skill in the art through arbitrary design changes to the display devices described above as embodiments of the present invention come within the scope of the present invention as long as they are in keeping with the spirit of the present invention.

Various types of the modified examples are easily conceivable within the category of the ideas of the present invention by a person of ordinary skill in the art and the modified examples are also considered to fall within the scope of the present invention. For example, additions, deletions or changes in design of the constituent elements or additions, omissions, or changes in condition of the processes arbitrarily conducted by a person of ordinary skill in the art, in the above embodiments, fall within the scope of the present invention as long as they are in keeping with the spirit of the present invention.

In addition, the other advantages of the aspects described in the embodiments, which are obvious from the descriptions of the present specification or which can be arbitrarily conceived by a person of ordinary skill in the art, are considered to be achievable by the present invention as a matter of course.