Patent Publication Number: US-2015085239-A1

Title: Liquid crystal display element and liquid crystal display device

Description:
TECHNICAL FIELD 
     The present invention relates to a liquid crystal display element and a liquid crystal display device, and particularly to a liquid crystal display element and a liquid crystal display device each of a vertical electric field type represented by a TN mode and a VA mode. 
     BACKGROUND ART 
     Recently, liquid crystal display devices are used in many kinds of devices. Examples of such devices include televisions and mobile phones. A liquid crystal display device is a display device including a liquid crystal display element which controls orientation of liquid crystal by controlling an electric field generated across electrodes and consequently controls transmittance of light. For the liquid crystal display element, there are many kinds of methods for controlling orientation of liquid crystal. Such methods can be roughly classified into a vertical electric field type and a horizontal electric field type, in view of a direction in which an electric field is generated. 
     A liquid crystal display element of a vertical electric field type includes a pair of transparent substrates positioned to face each other and a liquid crystal layer sandwiched between the pair of transparent substrates. One of the pair of transparent substrates is provided with pixel electrodes. The other of the pair of transparent substrates is provided with a counter electrode. By applying a voltage across the pixel electrodes and the counter electrode, an electric field perpendicular to the liquid crystal layer, i.e. an electric field in a vertical direction is generated. By controlling intensity and direction of the electric field in the vertical direction, orientation of liquid crystal is controlled. Representative examples of the liquid crystal display element of a vertical electric field type include a liquid crystal display element of a TN (twisted nematic) mode and a liquid crystal display element of a VA (vertical alignment) mode. 
     As an example of the liquid crystal display element of a vertical electric field type,  FIGS. 11 and 12  schematically illustrate a liquid crystal display element  200 . (a) of  FIG. 11  illustrates a plan view of the liquid crystal display element  200 , and (b) of  FIG. 11  illustrates a cross sectional view of the liquid crystal display element  200  taken along the line A-A of (a) of  FIG. 11 . (a) of  FIG. 12  illustrates an enlarged view of a part of (b) of  FIG. 11 . (b) of  FIG. 12  illustrates an enlarged view of a cross section of the liquid crystal display element  200  taken along a line on a scanning line  220  parallel to the line A-A of (a) of  FIG. 11 . 
     As illustrated in (b) of  FIG. 11 , the liquid crystal display element  200  includes a glass substrate  211  and a glass substrate  212  which are a pair of transparent substrates, and a liquid crystal layer  213  which is sandwiched between the glass substrate  211  and the glass substrate  212 . As illustrated in (a) of  FIG. 11 , the glass substrate  211  is provided with signal lines  219 , scanning lines  220 , TFTs (thin film transistors)  223 , pixel electrodes  230 , and common electrodes  240 . 
     The signal lines  219  are provided to be parallel to each other with a regular interval therebetween. The scanning lines  220  are provided to be parallel to each other with a regular interval therebetween. The signal lines  219  are orthogonal to the scanning lines  220 . Consequently, on a surface of the glass substrate  211 , rectangular regions each defined by one of the signal lines  219  and one of the scanning lines  220  are provided in a matrix manner. Each of the rectangular regions corresponds to one sub-pixel. One pixel includes three sub-pixels (of a red color, a green color, and a blue color, respectively). 
     One sub-pixel includes two TFTs. The TFTs are coplanar TFTs of a top gate type, and each include a gate electrode  223  which is a part of the scanning line  220 , an SI path  221 , and an SI path  222 . One end of the SI path  221  is provided with a source electrode (not illustrated). The source electrode is connected with the signal line  219  via a contact hole (not illustrated). On the other hand, the SI path  222  is connected with a drain electrode  224 . The drain electrode  224  is connected with a corresponding one of the pixel electrodes  230  via a contact hole (not illustrated). 
     While one of the scanning lines  220  is selected, an address signal is supplied to the one of the scanning lines  220 , and data signals are sequentially supplied to the signal lines  219 . Consequently, a voltage corresponding to the data signal is supplied to the SI path  222  and the pixel electrode  230 , so that an electric field in accordance with the data signal is generated between the pixel electrode  230  and a counter electrode  225 . 
     While none of the scanning lines  220  is selected, it is necessary for the liquid crystal display element  200  to maintain an electric field between the pixel electrode  230  and the counter electrode  225 . In order to generate storage capacitance for maintaining this electric field, a plurality of common electrodes  240  are provided. The plurality of common electrodes  240  are provided on an identical layer where the scanning lines  220  are provided, and are made of the same non-transparent metal conductive material as the material of the scanning lines  220 . The plurality of common electrodes  240  are provided to be parallel to the scanning lines  220 . Each common electrode  240  is provided between adjacent ones of the scanning lines  220 . 
     The liquid crystal display element of a horizontal electric field type includes a liquid crystal layer sandwiched between a pair of transparent substrates, as with the case of the liquid crystal display element of a vertical electric field type. However, the liquid crystal display element of a horizontal electric field type is different from the liquid crystal display element of a vertical electric field type in that one of the pair of transparent substrates is provided with pixel electrodes and common electrodes. In the liquid crystal display element of a horizontal electric field type, a voltage is applied across a pixel electrode and a corresponding common electrode in one of the transparent substrates, so that an electric field is generated in an in-plane direction of the liquid crystal layer, i.e. in a horizontal direction. Examples of the liquid crystal display element of a horizontal electric field type include a liquid crystal display element of an IPS (in-plane switching) mode and a liquid crystal display element of a FFS (fringe field switching) mode. 
     Patent Literature 1 describes a liquid crystal display element of a FFS mode in which an influence of a parasitic capacitance is reduced. The following description will discuss a feature of the invention of Patent Literature 1 with reference to  FIGS. 13 and 14 . 
       FIG. 13  is a view schematically illustrating a liquid crystal display element  300  of a FFS mode. (a) of  FIG. 13  illustrates a plan view of the liquid crystal display element  300 . (b) of  FIG. 13  is a cross sectional view of the liquid crystal display element  300  taken along the line A-A of (a) of  FIG. 13 .  FIG. 14  is an enlarged view of a part of (b) of  FIG. 13 . 
     As illustrated in (b) of  FIG. 13 , the liquid crystal display element  300  includes a glass substrate  311  and a glass substrate  312  which are a pair of transparent substrates, and a liquid crystal layer  313  which is sandwiched between the glass substrate  311  and the glass substrate  312 . As illustrated in (a) of  FIG. 13 , the glass substrate  311  is provided with signal lines  319 , scanning lines  320 , TFTs, pixel electrodes  330 , and a common electrode  340 . The common electrode  340  is made of a conductive material which is transparent in a visible region. 
     The signal lines  319  are provided to be parallel to each other at regular intervals therebetween. The scanning lines  320  are provided to be parallel to each other at regular intervals therebetween. The signal lines  319  are orthogonal to the scanning lines  320 . Consequently, on a surface of the glass substrate  311 , rectangular regions each defined by one of the signal lines  319  and one of the scanning lines  320  are provided in a matrix manner. Each of the rectangular regions corresponds to one sub-pixel. One pixel includes three sub-pixels (of a red color, a green color, and a blue color, respectively). 
     One sub-pixel includes two TFTs. The TFTs are coplanar TFTs of a top gate type, and each include a gate electrode  323  which is a part of the scanning line  320 , an SI path  321 , and an SI path  322 . The SI path  321 , a source electrode, and the signal line  319  are connected with one another via a contact hole (not illustrated). On the other hand, the SI path  322  is connected with a drain electrode  324 . The drain electrode  324  is connected with a pixel electrode  330  via a contact hole (not illustrated). The pixel electrode  330  has slits for generating an electric field between the pixel electrode  330  and the common electrode  340  which will be described later. 
     CITATION LIST 
     Patent Literatures 
     [Patent Literature 1] 
     Japanese Patent Application Publication, Tokukai, No. 2008-209686 (published on Sep. 11, 2008) 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the liquid crystal display element  200  having the above configuration, parasitic capacitances generated among the signal line  219 , the scanning line  220 , and the pixel electrode  230  deteriorate display quality. A description will be provided below as to this deterioration with reference to  FIG. 12 . 
     (a) of  FIG. 12  is an enlarged view of a part of (b) of  FIG. 11 . (b) of  FIG. 12  is an enlarged view of a cross section of the liquid crystal display element  200  taken along a line on the scanning line  220  parallel to the line A-A of (a) of  FIG. 11 . 
     As illustrated in (a) of  FIG. 12 , only an organic insulating film  217  exists between the signal line  219  and the pixel electrode  230 . Consequently, a parasitic capacitance Csd  227  is generated between the signal line  219  and the pixel electrode  230 . 
     As illustrated in (b) of  FIG. 12 , only an insulating film  216  and the organic insulating film  217  exist between the scanning line  220  and the pixel electrode  230 . Consequently, a parasitic capacitance Cgd  228  is generated between the scanning line  220  and the pixel electrode  230 . 
     These Csd  227  and Cgd  228  cause flickers and a crosstalk between pixels, thereby deteriorating display quality of the liquid crystal display element  200 . 
     One sub-pixel has, in addition to Csd  227  and Cgd  228 , a liquid crystal capacitance and a storage capacitance. The liquid crystal capacitance is generated between the pixel electrode  230  and the counter electrode  225 . The storage capacitance is generated between the common electrode  240  and the SI path  222 . A sum of the liquid crystal capacitance, the storage capacitance, Csd  227 , and Cgd  228  is considered as a pixel capacitance. As a ratio of the parasitic capacitance is larger with respect to the pixel capacitance, the parasitic capacitance has a larger influence on display quality of the liquid crystal display element  200 . In other words, when the pixel capacitance is increased by increasing the storage capacitance, the ratio of the parasitic capacitance with respect to the pixel capacitance can be decreased. Accordingly, it is possible to subdue the influence of the parasitic capacitance on display quality. 
     However, in order to design the liquid crystal display element  200  to have a larger storage capacitance, it is necessary to design the common electrode  240  to have a larger width (length of the common electrode  240  in a direction parallel to the signal line  219 ). Since the common electrode  240  is made of a non-transparent material, increasing the width of the common electrode  240  results in a narrower region which transmits backlight. Consequently, designing the liquid crystal display element  200  to have a larger storage capacitance so as to prevent the influence of the parasitic capacitance causes another problem that luminance of the liquid crystal display element  200  drops. 
     The liquid crystal display element  300  which is a liquid crystal display element of a horizontal electric field type includes the common electrode  340  so as to subdue the influence of the parasitic capacitance, and is characterized by a shape of the common electrode  340  and a position where the common electrode  340  is provided. On a plan view, the common electrode  340  is provided on a whole region other than the drain electrodes  324  and the contact holes (see (a) of  FIG. 13 ). On the other hand, on a cross sectional view, the common electrode  340  is provided between (i) a layer where the signal lines  319  are provided and a layer where the scanning lines  320  are provided and (ii) a layer where the pixel electrodes  330  are provided (see (b) of  FIG. 13 ). 
     Consequently, the signal lines  319  and the scanning lines  320  are shielded by the common electrode  340  from the pixel electrodes  330 . As a result, Csd which is a parasitic capacitance between the signal line  319  and the pixel electrode  330  and Cgd which is a parasitic capacitance between the scanning line  320  and the pixel electrode  330  are subdued. 
     By subduing Csd and Cgd, it is possible to stabilize a voltage maintained at the common electrode  340 . Therefore, it is possible to prevent deterioration in display quality of the liquid crystal display element  300 . 
     On the other hand, as illustrated in  FIG. 14 , since the common electrode  340  is provided on a whole region other than the drain electrodes  324  and the contact holes, it is necessary for the common electrode  340  to transmit backlight  329   a . An absorption ratio of the common electrode  340  is determined by (i) an absorption coefficient of a transparent conductive material constituting the common electrode  340  and (ii) a thickness of the common electrode  340 . Out of the backlight  329   a , light corresponding to the absorption ratio of the common electrode  340  is absorbed by the common electrode  340 , and light transmitted by the common electrode  340  becomes backlight  329   b . As described above, the liquid crystal display element  300  has a problem that luminance drops due to absorption of the backlight  329   a  into the common electrode  340 . It should be noted that absorption of the backlight  329   b  by the pixel electrodes  330  is not considered here. 
     In addition, the invention described in Patent Literature 1 is premised on a liquid crystal display element of a FFS mode, and so is not applicable to a liquid crystal display element of a vertical electric field type. 
     The present invention was made in view of the foregoing problems. An object of the present invention is to provide a liquid crystal display element of a vertical electric field type and a liquid crystal display device each capable of subduing a parasitic capacitance between (i) scanning lines and signal lines and (ii) pixel electrodes, without sacrificing luminance of the liquid crystal display element. 
     Solution to Problem 
     In order to solve the foregoing problems, a liquid crystal display element in accordance with one aspect of the present invention is a liquid crystal display element including a pair of transparent substrates and a liquid crystal layer provided between the pair of transparent substrates, 
     one of the pair of transparent substrates being provided with: 
     scanning lines; 
     signal lines orthogonal to the scanning lines; 
     driving elements connected with the signal lines and the scanning lines; 
     transparent pixel electrodes provided at a layer above a layer at which the scanning lines and the signal lines are provided, the transparent pixel electrodes being connected with the driving elements; and 
     a transparent common electrode,
         the transparent common electrode being provided at a layer between (i) the scanning lines and the signal lines and (ii) the transparent pixel electrodes,   the transparent common electrode covering a location which faces at least one of at least a part of the scanning lines and at least a part of the signal lines,   the transparent common electrode having openings at locations facing the transparent pixel electrodes, respectively, and   the transparent common electrode having a cutout section at a pixel boundary region in such a manner that the cutout section exists at least at a part of the pixel boundary region which part does not face the transparent pixel electrodes, the pixel boundary region being a region between adjacent ones of the transparent pixel electrodes which ones are adjacent in a signal line direction,   the other of the pair of transparent substrates being provided with a counter electrode.       

     With the arrangement, in the liquid crystal display element in accordance with one aspect of the present invention, the transparent common electrode is provided at a layer between (i) the scanning lines and the signal lines and (ii) the transparent pixel electrodes. Furthermore, at least one of at least a part of the scanning lines and at least a part of the signal lines is covered with the transparent common electrode. In the liquid crystal display element having this configuration, in a case where at least a part of the scanning line is covered with the transparent common electrode, a part of the scanning line and the pixel electrode are shielded from each other by the transparent common electrode. Similarly, in a case where at least a part of the signal line is covered with the transparent common electrode, a part of the signal line and the pixel electrode are shielded from each other by the transparent common electrode. This subdues a parasitic capacitance between (i) at least one of at least a part of the scanning line and at least a part of the signal line and (ii) the pixel electrode. 
     Furthermore, the transparent common electrode has openings at locations facing the transparent pixel electrodes. This allows more amount of light to enter the liquid crystal layer without being transmitted by the transparent common electrode. Consequently, the liquid crystal display element has improved luminance. 
     As described above, with the liquid crystal display element in accordance with one aspect of the present invention, it is possible to subdue a parasitic capacitance between (i) the scanning line and the signal line and (ii) the pixel electrode, without sacrificing luminance of the liquid crystal display element of a vertical electric field type. 
     Furthermore, with the arrangement, the transparent pixel electrode included in the liquid crystal display element in accordance with one embodiment of the present invention has a cutout section at a pixel boundary region in such a manner that the cutout section exists at least at a position of the pixel boundary region which position does not face the transparent pixel electrode. This allows regulating an electric field generated in the pixel boundary region, and consequently allows regulating alignment of liquid crystal molecules included in the pixel boundary region. Therefore, it is possible to subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings. 
     Advantageous Effects of Invention 
     The present invention allows a liquid crystal display element of a vertical electric field type to subdue a parasitic capacitance between the scanning line and the pixel electrode and a parasitic capacitance between the signal line and the pixel electrode, without sacrificing luminance. Therefore, the present invention yields an effect that a liquid crystal display element and a liquid crystal display device each of a vertical electric field type can improve display quality without sacrificing luminance. 
     Furthermore, the present invention allows regulating an electric field generated at the pixel boundary region which is a region between adjacent ones of the transparent pixel electrodes which are adjacent in a signal line direction, and consequently allows regulating alignment of liquid crystal molecules included in the pixel boundary region. Therefore, the present invention allows regulating a center of alignment of liquid crystal molecules in the pixel boundary region, and allows subduing display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       (a) of  FIG. 1  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. (b) of  FIG. 1  is a cross sectional view schematically illustrating a cross section of the liquid crystal display element. 
       (a) of  FIG. 2  is a view schematically illustrating how parasitic capacitance Csd between a signal line and a pixel electrode is subdued by a common electrode in the liquid crystal display element. (b) of  FIG. 2  is a view schematically illustrating how parasitic capacitance Cgd between a scanning line and a pixel electrode is subdued by a common electrode. (c) of  FIG. 2  is a view schematically illustrating how backlight is transmitted in the liquid crystal display element. 
         FIG. 3  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. 
         FIG. 4  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. 
       (a) of  FIG. 5  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. (b) of  FIG. 5  is a cross sectional view of the liquid crystal display element. 
       (a) of  FIG. 6  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. (b) and (c) of  FIG. 6  are cross sectional views of the liquid crystal display element. 
         FIG. 7  is a view illustrating an optical microscopic image of a liquid crystal display element in accordance with one embodiment of the present invention. 
         FIG. 8  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. 
         FIG. 9  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. 
         FIG. 10  is a plan view schematically illustrating a liquid crystal display element in accordance with one embodiment of the present invention. 
       (a) of  FIG. 11  is a plan view schematically illustrating a conventional liquid crystal display element. (b) of  FIG. 11  is a cross sectional view of the liquid crystal display element. 
       (a) of  FIG. 12  is a view schematically illustrating parasitic capacitance Csd between a signal line and a pixel electrode in a conventional liquid crystal display element. (b) of  FIG. 12  is a view schematically illustrating parasitic capacitance Cgd between a scanning line and a pixel electrode. 
       (a) of  FIG. 13  is a plan view schematically illustrating another conventional liquid crystal display element. (b) of  FIG. 13  is a cross sectional view of the liquid crystal display element. 
         FIG. 14  is a view illustrating how backlight is transmitted in another conventional liquid crystal display element. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following description will discuss embodiments of the present invention with reference to  FIGS. 1 to 10 . 
     First Embodiment 
     (Outline of Liquid Crystal Display Element  10 ) 
     With reference to  FIGS. 1 and 2 , the following description will discuss a liquid crystal display element  10  in accordance with one embodiment of the present invention. (a) of  FIG. 1  is a plan view schematically illustrating the liquid crystal display element  10 . (b) of  FIG. 1  is a cross sectional view schematically illustrating a cross section of the liquid crystal display element  10  taken along the line A-A of (a) of  FIG. 1 . (a) of  FIG. 2  is an enlarged view of a part of (b) of  FIG. 1 . (b) of  FIG. 2  is an enlarged view of a cross section of the liquid crystal display element  10  taken along a line on a scanning line  20  parallel to the line A-A of (a) of  FIG. 1 . (c) of  FIG. 2  is an enlarged view of a part of (b) of  FIG. 1 , similarly with (a) of  FIG. 2 . (c) of  FIG. 2  illustrates how backlight  29  enters a liquid crystal layer  13 . 
     The liquid crystal display element  10  is a VA mode liquid crystal display element which is one of liquid crystal display elements of a vertical electric field type. The liquid crystal display element  10  employs dot-inversion driving as a driving method. As illustrated in (b) of  FIG. 1 , the liquid crystal display element  10  includes a glass substrate  11  (one of a pair of transparent substrates), a glass substrate  12  (the other of the pair of transparent substrates), and a liquid crystal layer  13  sandwiched between the glass substrate  11  and the glass substrate  12 . A surface of the glass substrate  11  which surface is opposite to a surface thereof closer to the liquid crystal layer  13  is provided with a polarization plate (not illustrated) closely attached to that surface. Similarly, a surface of the glass substrate  12  which surface is opposite to a surface thereof closer to the liquid crystal layer  13  is provided with a polarization plate (not illustrated) closely attached to that surface. The liquid crystal display element  10  further includes a backlight (not illustrated) for emitting white light to the polarization plate closely attached to the glass substrate  11 . 
     On a surface of the glass substrate  12  which surface is closer to the liquid crystal layer  13 , a color filter  26  and a counter electrode  25  are laminated. The color filter  26  is a filter which selectively transmits light with a wavelength range of red, green, or blue out of white light which comes from the backlight and is transmitted by the liquid crystal layer  13 . Although not illustrated in (b) of  FIG. 1 , the color filter  26  is constituted by positioning red, green, and blue color filters in a matrix manner. The color filter  26  preferably includes a black matrix as well as the red, green, and blue color filters. 
     The liquid crystal display element  10  is characterized by a shape of a common electrode  40  (transparent common electrode) included in the glass substrate  11  and a position where the common electrode  40  is provided. Accordingly, the following description will discuss individual members laminated on the glass substrate  11  in details. A configuration known as a VA mode liquid crystal display element may be applied to the glass substrate  12  and the liquid crystal layer  13 . 
     (Configuration of Glass Substrate  11 ) 
     On a surface of the glass substrate  11  which surface is closer to the liquid crystal layer  13 , a base coat (BC)  14 , a plurality of SI paths  21 , a plurality of SI paths  22 , a first insulating film  15 , a plurality of scanning lines  20 , a second insulating film  16 , a plurality of signal lines  19 , an organic insulating film  17 , the common electrode  40 , a third insulating film  18 , and pixel electrodes  30  (transparent pixel electrodes) are sequentially laminated. 
     The signal lines  19  are provided to be parallel to each other at regular intervals therebetween, which will be detailed later. Similarly, the scanning lines  20  are provided to be parallel to each other at regular intervals therebetween. The signal lines  19  are orthogonal to the scanning lines  20  on a plan view. A rectangular region defined by one of the signal lines  19  and one of the scanning lines  20  corresponds to one sub-pixel. 
     Since (b) of  FIG. 1  is a cross sectional view of the liquid crystal display element  10  taken along the line A-A, (b) of  FIG. 1  does not illustrate the scanning lines  20 . The scanning lines  20  are provided on the first insulating film  15 . Similarly, (b) of  FIG. 1  does not illustrate the SI paths  21 . The SI paths  21  are provided on the same layer where the SI paths  22  are provided. 
     (TFT) 
     Two TFTs each serving as an element for driving the liquid crystal display element  10  are provided with respect to each sub-pixel region. Each TFT includes a gate electrode  23 , the SI path  21 , the SI path  22 , and a drain electrode  24 . The SI path  21  and the signal line  19  are connected with each other via a contact hole (not illustrated). In the TFT included in the liquid crystal display element  10 , the signal line  19  corresponds to a source electrode. One end of the SI path  22  is connected with the drain electrode  24 . The drain electrode  24  is connected with the pixel electrode  30  via a contact hole (not illustrated). 
     On the surface of the glass substrate  11 , the BC  14 , the SI paths  21 , and the SI paths  22  are formed firstly. The SI paths  21  and the SI paths  22  are each made of silicon. The BC  14  is made of, for example, Ta 2 O 5 . BC 14  serves as a protecting film for protecting the surface of the glass substrate  11 . Besides, when patterns of the SI paths  21  and the SI paths  22  are formed, the BC 14  also serves as an etching stopper. 
     At an interface among (i) the gate electrode  23  which is a part of the scanning line  20 , (ii) the SI path  21 , and (iii) the SI path  22 , there are provided a gate insulating layer and a channel layer which are not illustrated in (a) of  FIG. 1 . 
     (Scanning Line  20 ) 
     The scanning lines  20  and the first insulating film  15  are provided on the SI paths  21 , the SI paths  22 , and the BC  14 . The scanning lines  20  are provided to be parallel to each other with a regular interval therebetween. The scanning lines  20  are orthogonal in direction to the SI paths  22 . 
     Each of the TFTs is provided near an intersection between the scanning line  20  and the signal line  19 . 
     It is preferable that the scanning lines  20  have high conductivity and are made of a metal material. Examples of the metal material for the scanning lines  20  include aluminum, molybdenum, chrome, tungsten, and titanium. By forming a laminate film made of a plurality of these metal materials, it is possible to form the scanning lines  20  having high conductivity. Another example of the material for the scanning lines  20  may be a compound having conductivity. 
     The scanning lines  20  are provided on the first insulating film  15 . The first insulating film  15  is made of SiN x  or SiO 2 . It is necessary for the first insulating film  15  to transmit backlight entering the liquid crystal display element  10 . In order not to sacrifice luminance of the liquid crystal display element  10 , it is preferable that the first insulating film  15  has low optical absorbency with respect to light in a visible range. 
     The second insulating film  16  is provided on the first insulating film  15 . The second insulating film  16  is an interlayer insulating film which insulates the scanning lines  20  from the signal lines  19  (mentioned later). The second insulating film  16  is made of SiN x  or SiO 2 , similarly with the first insulating film  15 . It is preferable that the second insulating film  16  has low optical absorbency with respect to light in a visible range, similarly with the first insulating film  15 . 
     (Signal Line  19 ) 
     The signal lines  19  are provided on the second insulating film  16 . The signal lines  19  are provided to be parallel to each other at regular intervals therebetween. The signal lines  19  are orthogonal to the scanning lines  20  (see (a) of  FIG. 1 ). Consequently, on the glass substrate  11 , rectangular regions each defined by one of the signal lines  19  and one of the scanning lines  20  are provided in a matrix manner. Each of the rectangular regions corresponds to one sub-pixel. One pixel includes three sub-pixels (of a red color, a green color, and a blue color, respectively). 
     Each sub-pixel includes the aforementioned TFTs. The SI path  21  included in each TFT and the signal line  19  are electrically connected with each other via a contact hole (not illustrated). The contact hole has a shape which penetrates the first insulating film  15  and the second insulating film  16 . 
     It is preferable that the signal lines  19  have high conductivity and are made of a metal material, similarly with the scanning lines  20 . Examples of the metal material for the signal lines  19  include aluminum, molybdenum, chrome, tungsten, and titanium. By forming a laminate film made of a plurality of these metal materials, it is possible to form the signal lines  19  having high conductivity. Another example of the material for the signal lines  19  may be a compound having conductivity. 
     The organic insulating film  17  which is transparent is provided on the signal lines  19 . The organic insulating film  17  is an interlayer insulating film between the signal lines  19  and the common electrode  40  (mentioned later). It is preferable that the organic insulating film  17  is larger in thickness than the first insulating film  15 , the second insulating film  16 , and the third insulating film  18 . By forming the organic insulating film  17  to be thick, it is possible to planarize unevenness on a surface of the second insulating film  16  due to formation of the signal lines  19 , the scanning lines  20  etc. The organic insulating film is characterized in that it is easier to be formed as a planar-surfaced thick film than SiN x  or SiO 2  which constitutes other insulating film. 
     A region on a surface of the glass substrate  11  on which region pixels are provided in a matrix manner is hereinafter referred to as a pixel-provision region. 
     (Common Electrode  40 ) 
     The common electrode  40  is provided on the organic insulating film  17 . As illustrated in (a) of  FIG. 1 , the common electrode  40  has openings  41  each corresponding to one sub-pixel. At a part of a region where the opening  41  is provided, the drain electrode  24  and a contact hole (not illustrated) each for electrically connecting the corresponding SI path  22  with the corresponding pixel electrode  30  (mentioned later) are provided. In other words, the common electrode  40  has the openings  41  respectively at least at regions where the contact holes are provided. 
     Since the opening  41  is provided at the region where the contact hole is provided, it is possible to electrically insulate the SI path  22 , the drain electrode  24 , the pixel electrode  30 , and the common electrode  40  from one another. Since the SI path  22 , the drain electrode  24 , the pixel electrode  30 , and the common electrode  40  have different potentials, it is necessary to insulate them from one another in order to prevent leakages among them. 
     The opening  41  is not limited in its shape and its number as long as the opening  41  has a shape which secures electric insulation among the SI path  22 , the drain electrode  24 , the pixel electrode  30 , and the common electrode  40 . However, it should be noted that in a case where the common electrode  40  has a plurality of openings  41  with respect to each sub-pixel, there is a possibility that the size of a storage capacitance is not uniform among sub-pixels. In a case where the size of a storage capacitance is not uniform among sub-pixels, there is a possibility that the unevenness is recognized as display unevenness by a user. Therefore, it is preferable that the common electrode  40  has one opening  41  with respect to each sub-pixel. 
     The common electrode  40  is an electrode by which individual sub-pixels have storage capacitances. The storage capacitance is necessary for maintaining an electric field generated at a portion of the liquid crystal layer  13  which portion corresponds to the sub-pixel while an address signal is not supplied to the signal line  19 . 
     The common electrode  40  is provided on a whole of the pixel-provision region except for the openings  41 . Accordingly, the liquid crystal display element  10  includes one common electrode  40 , and individual parts of the common electrode  40  which parts correspond to respective sub-pixels have the same potential. 
     The common electrode  40  is made of indium tin oxide (ITO) or indium zinc oxide (IZO) which is a transparent conductive material. Since the common electrode  40  is provided on the pixel-provision region except for the openings  41 , the common electrode  40  preferably has a good optical transmittance in a visible region. Besides, the common electrode  40  preferably has a good electric conductivity. Even if the transparent conductive material is other than ITO and IZO, the transparent conductive material can be used for the common electrode  40  as long as the transparent conductive material has such a good optical transmittance and such a good electric conductivity. 
     The liquid crystal display element  10  is characterized by the common electrode  40 . What effect is yielded by the common electrode  40  included in the liquid crystal display element  10  will be described later. 
     The third insulating film  18  is provided on the common electrode  40 . The third insulating film  18  is an interlayer insulating film which insulates the common electrode  40  from the pixel electrodes  30 . The third insulating film  18  is made of SiN x  or SiO 2 , similarly with the first insulating film  15  and the second insulating film  16 . The third insulating film  18  preferably has a low optical absorbency with respect to light in a visible region, similarly with the first insulating film  15  and the second insulating film  16 . 
     (Pixel Electrode  30 ) 
     The pixel electrodes  30  are provided on the third insulating film  18 . One pixel electrode is provided for one sub-pixel. Consequently, the pixel electrodes  30  are provided on the pixel-provision region in a matrix manner. 
     The pixel electrode  30  is electrically connected with the SI path  22  included in the TFT via the drain electrode  24  and the contact hole. It is preferable that the drain electrode  24  and the contact hole are provided at a central part of a sub-pixel region defined by the signal line  19  and the scanning line  20  (see (a) of  FIG. 1 ). This is related to the fact that a region where the drain electrode  24  and the contact hole are provided does not transmit light. 
     Although not detailed, the liquid crystal display element  10  employing a VA mode is preferably designed such that each sub-pixel region on the counter electrode  25  has an alignment regulating section at a center of the sub-pixel region. The alignment regulating section may be a hole or a protrusion (rib). The alignment regulating section regulates alignment of liquid crystal molecules. While the alignment regulating section can improve an alignment property of liquid crystal, optical transmittance drops at a region where the hole is provided. By causing a position where the alignment regulating section is provided on the counter electrode  25  to correspond to a position where the drain electrode  24  and the contact hole are provided on the pixel electrode  30 , it is possible to subdue a loss in transmitted light in the liquid crystal display element  10 . That is, it is possible to increase luminance of the liquid crystal display element  10 . 
     The position of the hole included in the counter electrode  25  is not necessarily a center of the sub-pixel region. The number of the hole included in the counter electrode  25  may be two or more with respect to each sub-pixel region. The shape of the hole is not limited and may be elliptic. In these cases, it is preferable that the position where the drain electrode  24  and the contact hole are provided does not correspond to the center of the sub-pixel region but corresponds to the position where the hole is provided. 
     Alternatively, in order to regulate alignment of liquid crystal, the counter electrode  25  may include a protrusion instead of the hole. In this case, it is preferable that the position where the drain electrode  24  and the contact hole are provided corresponds to the position where the protrusion is provided. 
     In a case of a liquid crystal display element employing a TN mode, it is preferable that the drain electrode  24  and the contact hole are provided near an outer periphery of the sub-pixel region. This allows reducing an influence on alignment of liquid crystal. 
     The contact hole penetrates the first insulating film  15 , the second insulating film  16 , the organic insulating film  17 , and the third insulating film  18 , thereby connecting the drain electrode  24  with the pixel electrode  30 . 
     The pixel electrodes  30  are made of ITO or IZO. The pixel electrodes  30  are provided at a region of the liquid crystal display element  10  which region transmits light. Therefore, it is preferable that the pixel electrode  30  has good optical transmittance in a visible region. In addition, it is preferable that the pixel electrode  30  has good electrical conductivity. A transparent conductive material having such good optical transmittance and electrical conductivity can be used as the pixel electrode  30  even when the material is other than ITO and IZO. 
     Furthermore, on the pixel electrode  30  and the third insulating film  18 , there is provided an alignment film (not illustrated) for improving alignment of liquid crystal molecules. 
     (Effects of Common Electrode  40 ) 
     Effects yielded by the liquid crystal display element  10  including the common electrode  40  are subdual of a parasitic capacitance, securement of a suitable storage capacitance, and improvement of luminance of the liquid crystal display element. Individual effects will be described below. 
     (Subdual of Parasitic Capacitance) 
     On a cross sectional view of the liquid crystal display element  10 , the common electrode  40  is provided between the signal line  19  and the pixel electrode  30  and between the scanning line  20  and the pixel electrode  30  (see (b) of  FIG. 1 ). On the other hand, on a plan view of the liquid crystal display element  10 , the common electrode is provided on a whole region of the pixel-provision region other than the openings  41  (see (a) of  FIG. 1 ). 
     Therefore, on a cross section taken along the line A-A of (a) of  FIG. 1 , the signal line  19  and the pixel electrode  30  are shielded from each other by the common electrode  40  (see (a) of  FIG. 2 ). Consequently, a parasitic capacitance Csd 27  generated between the signal line  19  and the pixel electrode  30  is subdued. On a cross section taken along a line on the scanning line  20  parallel to the line A-A of (a) of  FIG. 1 , the scanning line  20  and the pixel electrode  30  are shielded from each other by the common electrode  40  (see (b) of  FIG. 2 ). Consequently, a parasitic capacitance Cgd 28  between the scanning line  20  and the pixel electrode  30  is subdued. 
     As described above, by the liquid crystal display element  10  including the common electrode  40 , the parasitic capacitances Csd 27  and Cgd 28  are subdued. Consequently, deterioration in display quality of the liquid crystal display element  10  due to Csd 27  and Cgd 28  is subdued. That is, the common electrode  40  yields an effect of improving the display quality of the liquid crystal display element  10 . 
     (Securement of Storage Capacitance) 
     In the liquid crystal display element  10 , a storage capacitance Ccs is provided between the common electrode  40  and the pixel electrodes  30 . The common electrode  40  and the pixel electrodes  30  overlap each other at a large region other than the openings  41 . Therefore, in the liquid crystal display element  10 , it is easy to provide Ccs with a sufficient size. It should be noted that there is provided the organic insulating film  17  with a large thickness between the common electrode  40  and the SI path. Accordingly, a capacitance provided between the common electrode  40  and the SI path is very small. 
     In order that the liquid crystal display element  10  has good display quality, there is a preferable range of a size of Ccs. In the liquid crystal display element  10 , it is possible to change Ccs freely by changing a size of the openings  41  of the common electrode  40 . Formation of the openings  41  with a larger size downsizes a region where the common electrode  40  and the pixel electrodes  30  overlap, resulting in smaller Ccs. On the other hand, formation of the openings  41  with a smaller size enlarges the region where the common electrode  40  and the pixel electrodes  30  overlap, resulting in larger Ccs. 
     Assume that a liquid crystal capacitance between the pixel electrode  30  and the counter electrode  25  is Cpix. It is preferable that a relation 0.6×Cpix≦Ccs≦0.95×Cpix is met. 
     By meeting a relation 0.6×Cpix≦Ccs, the liquid crystal display element  10  can have Ccs in a size sufficient to satisfy display quality. In other words, it is possible to maintain a stable electric field even when an address signal is not supplied to the scanning lines  20 . This prevents generation of flickers, so that the liquid crystal display element  10  can have satisfactory display quality. 
     In order to meet the relation 0.6×Cpix≦Ccs, it is necessary to set an area of the common electrode  40  on a plan view to be larger than a predetermined area which meets a relation Ccs=0.6×Cpix. Enlarging the area of the common electrode  40  indicates downsizing an area of the openings  41 . Downsizing the area of the openings  41  in the common electrode  40  reduces an electric resistance across both ends of the common electrode  40 . This allows subduing generation of a crosstalk between sub-pixels. Consequently, the liquid crystal display element  10  can have satisfactory display quality. 
     On the other hand, by meeting a relation Ccs≦0.95×Cpix, it is possible to sufficiently charge the storage capacitor during a period in which an address signal is supplied to the scanning line  20 . This allows suitably maintaining an electric field for controlling the liquid crystal layer  13  even during a period in which an address signal is not supplied to the scanning line  20 . 
     Assume a case where it is necessary to set the area of the openings  41  to be large in order to set Ccs in a suitable range. In this case, the area of the common electrode  40  would be downsized and there would be a possibility that an electric resistance across both ends of the common electrode  40  increases. In this case, by forming the common electrode  40  to have a larger thickness, it is possible to reduce the electric resistance across both ends of the common electrode  40 . 
     (Improvement of Luminance) 
     The common electrode  40  included in the liquid crystal display element  10  is made of ITO or IZO which is a transparent conductive material. Furthermore, the common electrode  40  includes the openings  41 , and on a plan view of the glass substrate  11 , at least a part of the openings  41  is provided at a region where the pixel electrodes  30  are provided. 
     As illustrated in a cross section illustrated in (c) of  FIG. 2 , the openings  41  allow the backlight  29  incident to the liquid crystal display element  10  to enter the liquid crystal layer  13  without being absorbed by the common electrode  40 . 
     On the other hand, even at a region where the backlight  29  incident to the liquid crystal display element  10  is transmitted by the common electrode  40  before entering the liquid crystal layer  13 , luminance of the liquid crystal display element  10  does not drop greatly since the common electrode  40  has good optical transmittance. 
     As described above, since the common electrode  40  included in the liquid crystal display element  10  is made of a transparent conductive material and includes the openings  41 , the liquid crystal display element  10  does not sacrifice luminance unlike a conventional liquid crystal display element including a common electrode made of a metal material. 
     A part of the openings  41  may be provided at a region other than the region where the pixel electrodes  30  are provided. However, it is preferable that at least a part of the openings  41  is provided at a region where the pixel electrodes  30  are provided together with contact holes  24 . 
     As described above, since the liquid crystal display element  10  of a vertical electric field type includes the common electrode  40 , the liquid crystal display element  10  can have a storage capacitance desirable for attaining satisfactory display quality while subduing a parasitic capacitance between (i) the scanning line and the signal line and (ii) the pixel electrode. Consequently, the liquid crystal display element  10  of a vertical electric field type can have improved display quality. 
     The liquid crystal display element  10  is not limited to a VA mode liquid crystal display element. The present invention is applicable to any liquid crystal display element of a vertical electric field type. 
     A liquid crystal display device in accordance with one aspect of the present invention may include the liquid crystal display element  10 . By the liquid crystal display device including the liquid crystal display element  10 , the liquid crystal display device can have improved display quality without sacrificing luminance. 
     Second Embodiment 
     (Liquid Crystal Display Element  50 ) 
     With reference to  FIG. 3 , the following description will discuss a liquid crystal display element  50  which is another embodiment of the present invention.  FIG. 3  is a plan view schematically illustrating the liquid crystal display element  50 . The liquid crystal display element  50  is different from the liquid crystal display element  10  in terms of shapes of a common electrode  51  and a TFT  53 . Accordingly, in the present embodiment, a description will be provided below as to the common electrode  51  and the TFT  53 . Members common between the liquid crystal display element  50  and the liquid crystal display element  10  are given identical reference numerals and explanations thereof are omitted. 
     (Common Electrode  51 ) 
     The liquid crystal display element  50  is a VA mode liquid crystal display element similarly with the liquid crystal display element  10 . However, the liquid crystal display element  10  is driven by dot-inversion driving, whereas the liquid crystal display element  50  is driven by row-inversion driving. Due to a difference in driving method, the common electrode  51  included in the liquid crystal display element  50  and the common electrode  40  included in the liquid crystal display element  10  have different shapes. 
     One common electrode  51  is provided for a plurality of sub-pixels connected with one scanning line  20 . Therefore, the liquid crystal display element  50  is shaped such that individual rows are independent from each other, so that individual common electrodes  51  are electrically insulated from each other. 
     Individual common electrodes  51  are connected with a CS driver for controlling a storage capacitance. In order that sub-pixels connected with the scanning lines  20  have suitable storage capacitances, the CS driver supplies suitable signals to the common electrodes  51 . 
     On a plan view, each of the common electrodes  51  is shaped so as to cover an entire region where the scanning line  20  is provided and to cover a part of a region where the signal line  19  is provided. The common electrode  51  in accordance with the present embodiment has a rectangular shape. However, the shape of the common electrode  51  is not limited to a rectangle as long as the common electrode  51  meets the aforementioned configuration. 
     Since the common electrode  51  has the aforementioned shape, it is possible to subdue Cgd which is a parasitic capacitance between the scanning line  20  and the pixel electrode  30  and a part of Csd which is a parasitic capacitance between the signal line  19  and the pixel electrode  30 . 
     Therefore, also in the liquid crystal display element  50  which is a vertical electric field type and is driven by row-inversion driving, it is possible to subdue an influence of a parasitic capacitance on display quality. That is, it is possible to improve display quality of the liquid crystal display element  50 . 
     (TFT) 
     A TFT included in the liquid crystal display element  50  is a TFT of a top-gate type. Each sub-pixel region has two TFTs near an intersection between the scanning line  20  and the signal line  19 . The TFT has a gate electrode  53 , a drain electrode  54 , an SI path  55 , and an SI path  56 . The TFT is different from the TFT included in the liquid crystal display element  10  in terms of shapes of the SI path and the gate electrode. 
     In the liquid crystal display element  50 , a conductive film which constitutes one gate electrode  53  is provided so as to extend from the scanning line  20  in a direction perpendicular to the scanning line  20  (see  FIG. 3 ). This conductive film is made of the same material as that of the scanning line  20 . 
     The SI path  55  intersects the scanning line  20 . Another gate electrode  53  is provided at this intersection. The SI path  55  connects said one gate electrode  53  with said another gate electrode  53 . Furthermore, the SI path  55  is connected with, at a portion crossing the scanning line  20 , the signal line  19  which also serves as a source electrode. The SI path  56  connects one of the two TFTs with the drain electrode  54 . 
     On an interface between (i) the gate electrode  53  and (ii) the SI path  55  and the SI path  56 , there are provided a gate insulating film and a channel layer. The SI path  55  and the SI path  56  are each made of silicon. 
     Third Embodiment 
     With reference to  FIG. 4 , the following description will discuss a liquid crystal display element  60  which is still another embodiment of the present invention. A common electrode  61  included in the liquid crystal display element  60  is different from the common electrode  51  included in the liquid crystal display element  50  in terms of the shape of an opening. The common electrode  51  has a rectangular shape. Accordingly, when a length of the common electrode  51  in a direction parallel to the signal line is regarded as a width of the common electrode  51 , the width is always constant. 
     In contrast, a width of the common electrode  61  is not constant. The width of the common electrode  61  is larger at a region where the signal line  19  is provided and at a surrounding region surrounding that region than at a region other than that region and the surrounding region. 
     This allows the common electrode  61  to cover a larger region out of the region where the signal line  19  is provided. Accordingly, the liquid crystal display element  60  can subdue a parasitic capacitance Csd between the signal line  19  and the pixel electrode  30  more effectively than the liquid crystal display element  50 . That is, the liquid crystal display element  60  can further improve display quality than the liquid crystal display element  50  can do. 
     Fourth Embodiment 
     (Liquid Crystal Display Element  110 ) 
     With reference to  FIGS. 5 to 7 , the following description will discuss a liquid crystal display element  110  in accordance with one embodiment of the present invention. (a) of  FIG. 5  is a plan view schematically illustrating the liquid crystal display element  110 . (b) of  FIG. 5  is a cross sectional view of the liquid crystal display element  110  taken along the line A-A of (a) of  FIG. 5 . As illustrated in  FIG. 5 , the liquid crystal display element  110  is based on the configuration of the liquid crystal display element  10  (see  FIG. 1 ). That is, the liquid crystal display element  110  includes a glass substrate  111  which is one of a pair of transparent substrates, a glass substrate  112  which is the other of the pair of transparent substrates, a liquid crystal layer  113 , a base coat (BC)  114 , a first insulating film  115 , a second insulating film  116 , an organic insulating film  117 , a third insulating film  118 , signal lines  119 , scanning lines  120 , SI paths  121 , SI paths  122 , gate electrodes  123 , drain electrodes  124 , a counter electrode  125 , a color filter  126 , pixel electrodes  130  which are transparent pixel electrodes, and a common electrode  140  which is a transparent common electrode. 
     In (a) of  FIG. 5 , only the SI path  121 , the SI path  122 , the gate electrode  123 , the drain electrode  124 , and the opening  141  in a sub-pixel sandwiched between two signal lines  119  are illustrated. The same can be said about  FIGS. 6 ,  8  through  10 . 
     In the present embodiment, a description will be provided below as to the scanning lines  120 , the counter electrode  125 , the pixel electrodes  130 , and the common electrode  140  which are characteristics of the liquid crystal display element  110 . Members other than these are common among the liquid crystal display element  110  and the liquid crystal display element  10  and so explanations thereof are omitted. 
     (Common Electrode  140 ) 
     As illustrated in (a) of  FIG. 5 , the common electrode  140  included in the liquid crystal display element  110  includes cutout sections  142  as well as openings  141 . Each of the cutout sections  142  may be provided at a pixel boundary region  146  between the pixel electrodes  130  adjacent in a signal line direction, so as not to face at least the pixel electrodes  130 . In the present embodiment, the cutout section  142  having a rectangular shape is illustrated in (a) of  FIG. 5 . However, the cutout section  142  is not particularly limited in shape. 
     It is preferable that the cutout section  142  is positioned such that a part of the cutout section  142  does not face the transparent pixel electrode but other part of the cutout section  142  faces the pixel electrode  130 . Furthermore, it is preferable that the cutout section  142  is positioned so as to be in a vicinity of one of two signal lines  119  which are provided on respective sides of the pixel electrode  130 . What merits are obtained by a part of the cutout section  142  facing the pixel electrode  130  and the cutout section  142  being in a vicinity of one of the signal lines  119  will be described later. 
     In the present embodiment, a description will be provided below as to a case where a part of the cutout section  142  faces the pixel electrode  130  and the cutout section  142  is in a vicinity of one of the signal lines  119 . 
     (a) of  FIG. 6  is a plan view schematically illustrating the liquid crystal display element  110  similarly with (a) of  FIG. 5 . (b) of  FIG. 6  is a cross sectional view illustrating the liquid crystal display element  110  taken along the line B-B of (a) of  FIG. 6 . (c) of  FIG. 6  is a cross sectional view illustrating the liquid crystal display element  110  taken along the line C-C of (a) of  FIG. 6 . 
     As illustrated in (a) of  FIG. 6 , the line B-B is a line which is parallel to the signal line  119  and which includes the cutout section  142 . Accordingly, as illustrated in (b) of  FIG. 6 , the common electrode  140  is not provided at the pixel boundary region  146 . The liquid crystal layer  113  corresponding to a region where the common electrode  140  is not provided is hereinafter referred to as a liquid crystal layer  113   a.    
     On the other hand, the line C-C is a line which is parallel to the signal line  119  and which does not include the cutout section  142 . Accordingly, as illustrated in (c) of  FIG. 6 , in the pixel boundary region  146 , the pixel electrode  130  is not provided, but the common electrode  140  is provided. The liquid crystal layer  113  corresponding to a region where the pixel electrode  130  is not provided but the common electrode  140  is provided is hereinafter referred to as a liquid crystal layer  113   b.    
     In the liquid crystal display element  110 , an identical voltage is applied to the common electrode  140  and the counter electrode  125 . Accordingly, the liquid crystal layer  113   b  illustrated in (c) of  FIG. 6  is sandwiched between the common electrode  140  and the pixel electrode  130  which have an identical potential. Consequently, only with the arrangement illustrated in (c) of  FIG. 6 , it would be difficult to apply, on the liquid crystal layer  113   b , an electric field effective for controlling orientation of liquid crystal molecules. 
     On the other hand, the liquid crystal layer  113   a  illustrated in (b) of  FIG. 6  is hardly influenced by the common electrode  140 . Accordingly, on the liquid crystal layer  113   a , an electric field effective for controlling orientation of liquid crystal molecules is applied in accordance with a voltage applied across the pixel electrode  130  and the counter electrode  125 . The electric field applied on the liquid crystal layer  113   a  is extended in a scanning line direction. Consequently, the electric field generated in accordance with the voltage applied across the pixel electrode  130  and the counter electrode  125  is applied not only on the liquid crystal layer  113   a  but also on the liquid crystal layer  113   b.    
     Consequently, in the liquid crystal display element  110 , it is possible to regulate alignment of the liquid crystal molecules included in the liquid crystal layer  113   b . An arrow illustrated in (a) of  FIG. 6  indicates an alignment direction  145  of liquid crystal molecules. The alignment direction  145  near the line B-B and the alignment direction  145  near the line C-C are different from each other. However, the alignment directions  145  are regulated orderly by application of effective electric fields on the liquid crystal layers  113   a  and  113   b . That is, with the cutout section  142 , the liquid crystal display element  110  can regulate a center of alignment of liquid crystal molecules in the pixel boundary region  146 . It is known that in a case where it is difficult to regulate the center of alignment of liquid crystal molecules in the pixel boundary region  146 , display deficiency such as roughness appears in an image displayed by the liquid crystal display element, so that display quality of the liquid crystal display element drops. Since the liquid crystal display element  110  can regulate the center of alignment of liquid crystal molecules in the pixel boundary region  146 , it is possible to subdue display deficiency such as roughness. 
     The liquid crystal display element  110  is based on the configuration of the liquid crystal display element  10 . Accordingly, the liquid crystal display element  110  can subdue a parasitic capacitance between the scanning line and the pixel electrode and a parasitic capacitance between the signal line and the pixel electrode, without sacrificing luminance of the liquid crystal display element  110 . In other words, the liquid crystal display element  110  can improve display quality without sacrificing luminance of the liquid crystal display element  110 . This is applicable to the liquid crystal display elements in accordance with Fifth to Seventh Embodiments. 
     It is preferable that a part of the cutout section  142  is positioned to face the pixel electrode  130 . This allows further effectively subduing an influence of the common electrode  140  on liquid crystal molecules included in the pixel boundary region  146 . Therefore, the liquid crystal display element  110  can regulate, with more precision, the center of alignment of liquid crystal molecules included in the pixel boundary region  146 . 
     Furthermore, it is preferable that the cutout section  142  is positioned to be in a vicinity of one of two signal lines  119  which are provided on respective sides of the pixel electrode  130 . In other words, it is preferable that in each sub-pixel region, the shape of the common electrode  140  is asymmetrical with respect to a line which is parallel to the signal line  119  and which passes through a center of the pixel. This allows distribution of an electric field in the pixel boundary region  146  to be localized on one side in a scanning line direction. Consequently, the liquid crystal display element  110  can regulate, with more precision, the center of alignment of liquid crystal molecules included in the pixel boundary region  146 . 
       FIG. 7  is a view illustrating an optical microscopic image of the liquid crystal display element  110  in a state where red, green, and blue sub-pixels display respective colors.  FIG. 7  illustrates that in each sub-pixel in the pixel boundary region  146 , the center of alignment is positioned identically. 
     (Counter Electrode  125 ) 
     As illustrated in (b) and (c) of  FIG. 6 , it is preferable that the counter electrode  125  includes an alignment regulating section  125 ′ in order to more precisely regulate alignment of liquid crystal molecules. The alignment regulating section  125 ′ may be, for example, a circular hole or a protrusion such as a rib. 
     In this configuration, the alignment regulating section  125 ′ is preferably positioned to face the opening  141 . There is a possibility that the alignment regulating section  125 ′ and the opening section  141  both drop optical transmittance. By positioning the alignment regulating section  125 ′ and the opening section  141  to face each other, it is possible to subdue drop of optical transmittance in other regions in a pixel. 
     (Scanning Line  120 ) 
     The scanning line  120  included in the liquid crystal display element  110  is positioned to be near a center of a pixel (which center substantially corresponds to a position where the drain electrode  124  is provided) and to face the pixel electrode  130  (see (a) of  FIG. 5 ). Since the alignment regulating section  125 ′ and the opening  141  are provided near the center of the pixel, optical transmittance at the region is not high. By providing the region with the scanning line  120 , it is possible to subdue drop of optical transmittance in other regions in the pixel. In other words, by positioning the scanning line  120  to be near the center of the pixel and to face the pixel electrode  130 , it is possible to enhance an open area ratio of the liquid crystal display element  110 . 
     (Pixel Electrode  130 ) 
     The pixel electrode  130  included in the liquid crystal display element  110  is made of a transparent conductive material similarly with the pixel electrode  30  included in the liquid crystal display element  10 . It is preferable that out of edges of the pixel electrode  130  in a signal line direction, at least a part of each edge of the pixel electrode  130  which edge faces the cutout section  142  has an inclination which is monotonously closer to a pixel boundary line  147  as said at least a part of each edge is farther from one of the two signal lines in the vicinity of which one the cutout section  142  is provided. By the pixel electrode  130  having such an inclined edge, it is possible to more precisely regulate the center of alignment of liquid crystal molecules included in the pixel boundary region  146 . Consequently, it is possible to more surely subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. Furthermore, since the cutout section  142  is shaped in such a manner that a part of the cutout section  142  faces the pixel electrode  130 , an effect yielded by the pixel electrode  130  having an inclined edge is further enhanced. 
     The pixel electrode  130  may be arranged such that edges of the pixel electrode  130  which edges face the cutout section  142  are all inclined edges. 
     Fifth Embodiment 
     (Liquid Crystal Display Element  150 ) 
     With reference to  FIG. 8 , the following description will discuss a liquid crystal display element  150  in accordance with one embodiment of the present invention.  FIG. 8  is a plan view schematically illustrating the liquid crystal display element  150 . The liquid crystal display element  150  is a liquid crystal display element obtained by arranging the liquid crystal display element  110  of Fourth Embodiment to change the positions of the scanning lines  120 . As illustrated in  FIG. 8 , the scanning line  120  included in the liquid crystal display element  150  is provided at the pixel boundary region  146 . 
     By the scanning line  120  being provided at the pixel boundary region  146  which is far from the center of the pixel, it is possible to secure a long distance between (i) a connection section connected with the drain electrode  124  of a TFT (driving element) and with the pixel electrode  130  and (ii) the gate electrode  123  of the TFT. With the arrangement, similarly with the liquid crystal display element  110 , the liquid crystal display element  150  can subdue display deficiency such as roughness and improve a yield in the production step. 
     Sixth Embodiment 
     (Liquid Crystal Display Element  160 ) 
     With reference to  FIG. 9 , the following description will discuss a liquid crystal display element  160  in accordance with one embodiment of the present invention.  FIG. 9  is a plan view schematically illustrating the liquid crystal display element  160 . The liquid crystal display element  160  is different from the liquid crystal display element  110  in accordance with Fourth Embodiment in that the liquid crystal display element  160  includes pixel electrodes  161  having a rectangular shape. The pixel electrode  161  having a rectangular shape can apply a voltage on a wider range of a pixel region than the pixel electrode  130  having an inclined edge can do. That is, the liquid crystal display element  160  including the pixel electrodes  161  having a rectangular shape has an improved open area ratio. Consequently, the liquid crystal display element  160  has increased luminance. 
     Since the liquid crystal display element  160  includes the cutout sections  142 , it is possible to regulate a center of alignment of liquid crystal molecules included in the pixel boundary region  146 . Accordingly, the liquid crystal display element  160  can subdue display deficiency such as roughness and has high luminance. 
     Seventh Embodiment 
     (Liquid Crystal Display Element  170 ) 
     With reference to  FIG. 10 , the following description will discuss a liquid crystal display element  170  in accordance with one embodiment of the present invention.  FIG. 10  is a plan view schematically illustrating the liquid crystal display element  170 . The liquid crystal display element  170  is a liquid crystal display element obtained by arranging the liquid crystal display element  160  in accordance with Sixth Embodiment to change the positions of the scanning lines  120 . As illustrated in  FIG. 10 , the scanning line  120  included in the liquid crystal display element  170  is provided at the pixel boundary region  146 . 
     By the scanning line  120  being provided at the pixel boundary region  146  which is far from the center of the pixel, it is possible to secure a long distance between (i) a connection section connected with the drain electrode  124  of a TFT (driving element) and with the pixel electrode  130  and (ii) the gate electrode  123  of the TFT. With the arrangement, the liquid crystal display element  170  can improve a yield in the production step. 
     Furthermore, the liquid crystal display element  170  includes a pixel electrode  161  having a rectangular shape. Consequently, the liquid crystal display element  170  has an improved open area ratio and increased luminance. 
     Besides, since the liquid crystal display element  170  includes the cutout section  142  similarly with the liquid crystal display elements in accordance with other embodiments of the present invention, it is possible to regulate a center of alignment of liquid crystal molecules included in the pixel boundary region  146 . Accordingly, the liquid crystal display element  170  can subdue display deficiency such as roughness, has high luminance, and can improve a yield in the production step. 
     It is preferable that a liquid crystal display device in accordance with one embodiment of the present invention includes any one of the liquid crystal display elements in accordance with Fourth to Seventh Embodiments. With this arrangement, the liquid crystal display device in accordance with one embodiment of the present invention can yield an effect similar to that yielded by the liquid crystal display elements in accordance with Fourth to Seventh Embodiments. 
     SUMMARY 
     A liquid crystal display element in accordance with first aspect of the present invention is a liquid crystal display element, including a pair of transparent substrates ( 111 ,  112 ) and a liquid crystal layer ( 113 ) provided between the pair of transparent substrates ( 111 ,  112 ), 
     one ( 111 ) of the pair of transparent substrates being provided with: 
     scanning lines ( 120 ); 
     signal lines ( 119 ) orthogonal to the scanning lines ( 120 ); 
     driving elements (TFT including the gate electrode  123 , the SI path  121 , the SI path  122 , and the drain electrode  124 ) connected with the signal lines and the scanning lines; 
     transparent pixel electrodes ( 130 ) provided at a layer above a layer at which the scanning lines ( 120 ) and the signal lines ( 119 ) are provided, the transparent pixel electrodes ( 130 ) being connected with the driving elements (TFT); and 
     a transparent common electrode ( 140 ),
         the transparent common electrode ( 140 ) being provided at a layer between (i) the scanning lines ( 120 ) and the signal lines ( 119 ) and (ii) the transparent pixel electrodes ( 130 ),   the transparent common electrode ( 140 ) covering a location which faces at least one of at least a part of the scanning lines ( 120 ) and at least a part of the signal lines ( 119 ),   the transparent common electrode ( 140 ) having openings ( 141 ) at locations facing the transparent pixel electrodes ( 130 ), respectively, and   the transparent common electrode ( 140 ) having a cutout section ( 142 ) at a pixel boundary region ( 146 ) in such a manner that the cutout section ( 142 ) exists at least at a part of the pixel boundary region ( 146 ) which part does not face the transparent pixel electrodes ( 130 ), the pixel boundary region ( 146 ) being a region between adjacent ones of the transparent pixel electrodes ( 130 ) which ones are adjacent in a signal line direction,       

     the other ( 112 ) of the pair of transparent substrates being provided with a counter electrode ( 125 ). 
     With the arrangement, in the liquid crystal display element in accordance with one aspect of the present invention, the transparent common electrode is provided at a layer between (i) the scanning lines and the signal lines and (ii) the transparent pixel electrodes. Furthermore, at least one of at least a part of the scanning lines and at least a part of the signal lines is covered with the transparent common electrode. In the liquid crystal display element having this configuration, in a case where at least a part of the scanning line is covered with the transparent common electrode, a part of the scanning line and the pixel electrode are shielded from each other by the transparent common electrode. Similarly, in a case where at least a part of the signal line is covered with the transparent common electrode, a part of the signal line and the pixel electrode are shielded from each other by the transparent common electrode. This subdues a parasitic capacitance between (i) at least one of at least a part of the scanning line and at least a part of the signal line and (ii) the pixel electrode. 
     Furthermore, the transparent common electrode has openings at locations facing the transparent pixel electrodes. This allows more amount of light to enter the liquid crystal layer without being transmitted by the transparent common electrode. Consequently, the liquid crystal display element has improved luminance. 
     As described above, with the liquid crystal display element in accordance with one aspect of the present invention, it is possible to subdue a parasitic capacitance between (i) the scanning line and the signal line and (ii) the pixel electrode, without sacrificing luminance of the liquid crystal display element of a vertical electric field type. 
     Furthermore, with the arrangement, the transparent pixel electrode included in the liquid crystal display element in accordance with one embodiment of the present invention has a cutout section at a pixel boundary region in such a manner that the cutout section exists at least at a part of the pixel boundary region which part does not face the transparent pixel electrodes. This allows regulating an electric field generated in the pixel boundary region, and consequently allows regulating alignment of liquid crystal molecules included in the pixel boundary region. Therefore, it is possible to subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     A liquid crystal display element in accordance with second aspect of the present invention is preferably an arrangement of the first aspect, in which a part of the cutout section ( 142 ) is positioned to face the transparent pixel electrodes ( 130 ). 
     With the arrangement, regulation of an electric field generated in the pixel boundary region in a signal line direction is enhanced. Therefore, it is possible to regulate a center of alignment of liquid crystal molecules in the region with more precision, so that it is possible to more surely subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     A liquid crystal display element in accordance with third aspect of the present invention is preferably an arrangement of the first or second aspect, in which the cutout section ( 142 ) is provided so as to be in a vicinity of one ( 119 ) of two signal lines ( 119 ) provided at respective sides of each of the transparent pixel electrodes ( 130 ). 
     With the arrangement, the transparent common electrode included in the display element in accordance with one aspect of the present invention has an asymmetrical shape in the signal line direction. Since the transparent common electrode has an asymmetrical shape in the signal line direction, distribution of strength of an electric field generated in the pixel boundary region is asymmetrical in the signal line direction. Consequently, regulation of the electric field generated in the pixel boundary region in the signal line direction is enhanced. This allows regulating a center of alignment of liquid crystal molecules in the region with more precision, and allows more surely subduing display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     A liquid crystal display element in accordance with fourth aspect of the present invention is preferably an arrangement of the third aspect, in which out of edges of each of the transparent pixel electrodes ( 130 ) in a signal line direction, at least a part of each edge of said each transparent pixel electrode ( 130 ) which edge faces the cutout section ( 142 ) has an inclination which is monotonously closer to the pixel boundary region ( 147 ) as the inclined edge is farther from one ( 119 ) of the two signal lines ( 119 ) in the vicinity of which one the cutout section ( 142 ) is provided. 
     With the arrangement, it is possible to regulate a center of alignment of liquid crystal molecules in the region with more precision, and it is possible to more surely subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     A liquid crystal display element in accordance with fifth aspect of the present invention is preferably an arrangement of one of the first through fourth aspects, in which each of the scanning lines ( 120 ) is provided near centers of corresponding pixels so as to face corresponding ones of the transparent pixel electrodes ( 130 ). 
     With the arrangement, each of the scanning lines is provided near centers of corresponding pixels so as to face corresponding ones of the transparent pixel electrodes. A region near the center of a pixel does not have high optical transmittance. By providing the scanning line at the region near the center of a pixel which region does not have high optical transmittance, it is possible to subdue drop in optical transmittance in other regions in the pixel. In other words, an open area ratio of the liquid crystal display device is enhanced. 
     A liquid crystal display element in accordance with sixth aspect of the present invention is preferably an arrangement of one of the first through fourth aspects, in which each of the scanning lines ( 120 ) is provided at the corresponding pixel boundary region ( 146 ). 
     With the arrangement, it is possible to secure a long distance between (i) a gate electrode of the driving element and (ii) a connection section connected with a drain electrode of the driving element and with the transparent pixel electrode. This allows enhancing a yield in production of the liquid crystal display element. 
     A liquid crystal display device in accordance with seventh aspect of the present invention preferably includes a liquid crystal display element in accordance with one of the first through sixth aspects. 
     With the arrangement, in the liquid crystal display device including the liquid crystal display element of a vertical electric field type, it is possible to subdue a parasitic capacitance between (i) the scanning line and the signal line and (ii) the pixel electrode. Furthermore, it is possible to subdue display deficiency such as roughness due to variations in alignment of liquid crystal molecules. 
     The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person within the scope of the claims. An embodiment based on a proper combination of technical means disclosed in different embodiments is encompassed in the technical scope of the present invention. 
     The embodiments and concrete examples of implementation discussed in the foregoing detailed explanation serve solely to illustrate the technical details of the present invention, which should not be narrowly interpreted within the limits of such embodiments and concrete examples, but rather may be applied in many variations within the spirit of the present invention, provided such variations do not exceed the scope of the patent claims set forth below. 
     INDUSTRIAL APPLICABILITY 
     The present invention is widely usable as a liquid crystal display element and a liquid crystal display device. 
     REFERENCE SIGNS LIST 
     
         
           110  Liquid crystal display element 
           111  Glass substrate (one of transparent substrates) 
           112  Glass substrate (the other of transparent substrates) 
           113  Liquid crystal layer 
           114  Base coat 
           115  First insulating film 
           116  Second insulating film 
           117  Organic insulating film 
           118  Third insulating film 
           119  Signal line 
           120  Scanning line 
           121  SI path 
           122  SI path 
           123  Gate electrode 
           124  Drain electrode 
           125  Counter electrode 
           126  Color filter 
           130  Pixel electrode (transparent pixel electrode) 
           140  Common electrode (transparent common electrode) 
           141  Opening 
           142  Cutout section 
           145  Alignment direction 
           146  Pixel boundary region 
           147  Pixel boundary line