Patent Publication Number: US-10788719-B2

Title: Liquid crystal display device

Description:
This application claims priority to Korean Patent Application No. 10-2015-0191111, filed on Dec. 31, 2015, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference. 
     BACKGROUND 
     1. Field 
     Exemplary embodiments of the invention relate to a liquid crystal display device. 
     2. Description of the Related Art 
     An importance of display devices is increasing along with a development of multimedia. Accordingly, various kinds of display devices such as a liquid crystal display (“LCD”) and an organic light emitting display (“OLED”) are being used. 
     An LCD device is one of the currently most widely used flat panel display devices, and generally includes two substrates on which electric field generating electrodes, such as pixel electrodes and a common electrode, are formed, and a liquid crystal layer interposed between the two substrates. The LCD device applies voltages to the electric field generating electrodes so as to generate an electric field in the liquid crystal layer, which determines the alignment direction of liquid crystal molecules in the liquid crystal layer to control polarization of incident light, thereby displaying desired images. 
     SUMMARY 
     In a liquid crystal display device (“LCD”), when a spacing distance between neighboring pixel electrodes is short, transmittance may increase but color mixture defects may also increase. On the contrary, when a spacing distance between neighboring pixel electrodes is long, color mixture defects may decrease but transmittance may also decrease. 
     An exemplary embodiment of the invention provides an LCD device in which color mixture defects are prevented even when a spacing distance between pixel electrodes is decreased. 
     Another exemplary embodiment of the invention provides an LCD device with improved transmittance. 
     Another exemplary embodiment of the invention provides an LCD device in which light leakage caused by a coupling phenomenon between data lines and pixel electrodes is prevented. 
     However, exemplary embodiments of the invention are not restricted to those set forth herein. The other exemplary embodiments of the invention which are not mentioned herein will become more apparent to a person skilled in the art to which the invention pertains by referencing the detailed description of the invention given below. 
     According to an exemplary embodiment of the invention, there is provided an LCD device in which at least one slit is defined in a common electrode, thereby preventing color mixture defects. 
     According to another exemplary embodiment of the invention, there is provided an LCD device in which a spacing distance between pixel electrodes is decreased to achieve improved transmittance. 
     According to another exemplary embodiment of the invention, there is provided an LCD device in which a slit of a common electrode is defined in a region non-overlapping data lines, thereby preventing light leakage caused by a coupling phenomenon between the data lines and pixel electrodes. 
     An exemplary embodiment of the invention discloses an LCD device including first to fourth pixel electrodes neighbored each other in a first direction, a common electrode at least partially overlapping the first to fourth pixel electrodes, and a first data line and a second data line extended in a second direction different from the first direction, and neighbored each other. The first data line may be interposed between the first pixel electrode and the second pixel electrode, and the second data line is interposed between the third pixel electrode and the fourth pixel electrode, and at least one slit interposed between the second pixel electrode and the third pixel electrode may be defined in the common electrode. 
     An exemplary embodiment of the invention also discloses an LCD device including a first data line and a second data line neighbored each other on a lower substrate, first to fourth pixel electrodes neighbored each other on the first data line and the second data line, and a common electrode which at least partially overlaps the first to fourth pixel electrodes, and in which at least one slit is defined. The first data line may overlap a first region between the first pixel electrode and the second pixel electrode, and the second data line overlaps with a second region between the third pixel electrode and the fourth pixel electrode, and the at least one slit may overlap a third region between the second pixel electrode and the third pixel electrode. 
     An exemplary embodiment of the invention also discloses an LCD device including first to fourth pixel electrodes neighbored each other in a first direction, at least one slit interposed between the second pixel electrode and the third pixel electrode is defined in a common electrode, and a first data line and a second data line extended in a second direction different from the first direction, and disposed adjacent to each other. The first data line may be interposed between the first pixel electrode and the second pixel electrode and connected respectively to the first pixel electrode and the second pixel electrode, and the second data line is interposed between the third pixel electrode and the fourth pixel electrode and connected respectively to the third pixel electrode and the fourth pixel electrode, and no data line may be disposed between the second pixel electrode and the third pixel electrode. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and, together with the description, serve to explain principles of the invention. 
         FIG. 1  schematically illustrates an exemplary embodiment of a display panel of a liquid crystal display (“LCD”) device according to the invention; 
         FIG. 2  schematically illustrates another exemplary embodiment of a display panel of an LCD device according to the invention; 
         FIG. 3  illustrates the display panel of  FIG. 1 , in which a slit is defined; 
         FIG. 4  is a circuit diagram illustrating the details of first to fourth pixels of A region shown in  FIG. 1 ; 
         FIG. 5  is a plan view illustrating in detail one embodiment of first to fourth pixels of the display panel shown in  FIG. 4 ; 
         FIG. 6  is a cross sectional view taken along lines I 1 -I 1 ′, I 2 -I 2 ′ and I 3 -I 3 ′ of the plan view of  FIG. 5 ; 
         FIG. 7  is a cross sectional view taken along line I 4 -I 4 ′ of the plan view of  FIG. 5 ; 
         FIG. 8  is a plan view illustrating another exemplary embodiment of a slit shown in  FIG. 5 ; 
         FIG. 9  is a plan view illustrating another exemplary embodiment of the slit shown in  FIG. 5 ; 
         FIG. 10  is a plan view illustrating another exemplary embodiment of the slit shown in  FIG. 5 ; 
         FIG. 11  is a plan view illustrating in detail another exemplary embodiment of first to fourth pixels of the display panel shown in  FIG. 4 ; 
         FIG. 12  is a cross sectional view taken along lines I 1 -I 1 ′, I 2 -I 2 ′ and I 3 -I 3 ′ of the plan view of  FIG. 11 ; 
         FIG. 13  is a cross sectional view taken along line I 4 -I 4 ′ of the plan view of  FIG. 11 ; 
         FIG. 14  illustrates the degree of light leakage when a common electrode is disposed on data lines (a), and the degree of light leakage when no common electrode is disposed on the data lines (b); 
         FIGS. 15 and 16  comparatively illustrate an exemplary embodiment of the invention and conventional techniques of the transmittance and color mixture defects of the LCD devices; and 
         FIGS. 17 and 18  illustrate an exemplary embodiment of an arrangement of pixel electrodes of the LCD device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments. It is apparent, however, that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various exemplary embodiments. 
     In the accompanying figures, the size and relative sizes of layers, films, panels, regions, etc., may be exaggerated for clarity and descriptive purposes. Also, like reference numerals denote like elements. 
     When an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. Thus, a first element, component, region, layer, and/or section discussed below could be termed a second element, component, region, layer, and/or section without departing from the teachings of the present disclosure. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for descriptive purposes, and, thereby, to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value. 
     Various exemplary embodiments are described herein with reference to sectional illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments disclosed herein should not be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the drawings are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to be limiting. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense, unless expressly so defined herein. 
     Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. 
       FIG. 1  schematically illustrates a display panel P of a liquid crystal display (“LCD”) device according to an exemplary embodiment of the invention.  FIG. 2  schematically illustrates a display panel P′ of an LCD device according to another exemplary embodiment of the invention.  FIG. 3  illustrates the display panel of  FIG. 1 , in which a slit is added. 
     Referring first to  FIG. 1 , a plurality of gate lines GL 1  to GLn may extend in a first direction d 1 , and a plurality of data lines DL 1  to DLm may extend in a second direction d 2  different from the first direction d 1 , where n and m are natural numbers greater than 1. The first direction d 1  and the second direction d 2  may intersect each other in a perpendicular direction. Hereinafter, the first direction d 1  will be also referred to as a column direction, and the second direction d 2  will be also referred to as a row line. 
     The plurality of gate lines GL 1  to GLn may be insulated from the plurality of data lines DL 1  to DLm. The plurality of gate lines GL 1  to GLn may be connected to a gate driving unit (not shown in the drawings) so as to receive respectively a plurality of gate signals from the gate driving unit. The plurality of data lines DL 1  to DLm may be connected to a data driving unit (not shown) so as to receive respectively a plurality of data signals from the data driving unit. 
     The display panel P may display an image. The display panel P may be connected to the plurality of gate lines GL 1  to GLn and the plurality of data lines DL 1  to DLm. More specifically, the display panel P may include a plurality of pixel electrodes PE 11  to PEnm, and a plurality of switching elements connected respectively to the pixel electrodes PE 11  to PEnm. Each of the pixel electrodes PE 11  to PEnm may be connected to the gate lines and the data lines through the plurality of switching elements. The switching elements may be turned on when gate signals are received from the gate lines connected thereto, and receive data signals from the data lines connected thereto and provide the received data signals to the pixel electrodes. 
     The display panel P of the LCD device according to an exemplary embodiment of the invention may have two pixel electrodes PEs neighboring each other and sharing one data line. In an exemplary embodiment, the pixel electrode PE 11  connected to the first gate line GL 1  may share the first data line DL 1  with the pixel electrode PE 12  connected to the second gate line GL 2 , for example. Furthermore, the pixel electrode PE 13  connected to the second gate line GL 2  may share the second data line DL 2  with the pixel electrode PE 14  connected to the first gate line GL 1 . Hereinafter, the expression “neighboring each other” as used herein means that two components are consecutively disposed one after the other. In an exemplary embodiment, the expression “the first and second data lines DL 1  and DL 2  neighboring each other” means that no separate data line is interposed between the first and second data lines DL 1  and DL 2 . 
     When two pixel electrodes neighboring each other in the same direction share one data line therebetween, the two pixel electrodes may be connected to gate lines different from each other. In an exemplary embodiment, two pixel electrodes PE 11  and PE 12  sharing the first data line DL 1  may be connected respectively to gate lines GL 1  and GL 2  different from each other, for example. However, the connection structure of pixel electrodes PE 11  and PE 12  and gate lines GL 1  and GL 2  is not limited to those shown in  FIG. 1 , and the pixel electrode PE 14  may be connected to the second gate line GL 2  and the other pixel electrode PE 13  may be connected to the first gate line GL 1  as shown in  FIG. 2 . That is, as shown in  FIG. 2 , the display panel P′ of the LCD device according to another exemplary embodiment of the invention differs from the display panel P of the LCD device according to an exemplary embodiment of the invention with respect to the connection structure between the gate line and two pixel electrodes neighboring in the first direction d 1  and sharing one data line. Hereinafter, the display panel P of the LCD device according to an exemplary embodiment of the invention shown in  FIG. 1  will be described. 
     Referring to  FIGS. 1 and 3 , a slit  171  of a common electrode  170  (refer to  FIG. 6 ) may be interposed between two pixel electrodes neighboring each other but not sharing a data line. In an exemplary embodiment, the slit  171  of the common electrode  170  may be interposed between the pixel electrode PE 12  which receives a data signal from the first data line DL 1  and the pixel electrode PE 13  which receives a data signal from the second data line DL 2 . The slit  171  of the common electrode  170  is illustrated by dot lines in  FIG. 3  in order to show the location of the slit  171 , and the shape or size of the slit  171  is not necessarily limited to those shown in  FIG. 3 . 
     That is, the slit  171  of the common electrode  170  may be defined so as not to overlap the plurality of data lines DL 1  to DLm. More specifically, the slit  171  of the common electrode  170  may extend in the second direction d 2  same as the direction of the plurality of data lines DL 1  to DLm, and may be defined in a region in which the plurality of data lines DL 1  to DLm are not disposed. 
     Data signals having different polarities may be applied to data lines neighboring each other. In an exemplary embodiment, when a data signal having a first polarity (+) is applied to the first data line DL 1 , a data signal having a second polarity (−) different from the first polarity (+) may be applied to the second data line DL 2 . In this case, the data signal having a second polarity (−) may have a phase opposite to the phase of the data signal having a first polarity (+). Resultantly, data signals having different polarities may be applied to two pixel electrodes neighboring each other in the first direction d 1 , pixel electrodes which receive data signals having the same polarity may be distributed uniformly in the display panel P. 
     The slit  171  of the common electrode  170  may be plural in number, and as an exemplary embodiment, at least one slit  171  may be disposed in a region between two neighboring pixel electrodes in which the plurality of data lines DL 1  to DLm are not disposed. That is, the slit  171  of the common electrode  170  may be defined in all of the regions between two neighboring pixel electrodes in which the plurality of data lines DL 1  to DLm are not disposed, or alternatively, the slit  171  may be omitted in a part of the regions. 
       FIG. 4  is a circuit diagram illustrating the details of first to fourth pixels of A region shown in  FIG. 1 . 
     The first to fourth pixels will be described in detail with reference to  FIG. 4 . The first to fourth pixel electrodes PE 21  to PE 24  may be disposed neighboring to each other in the first direction d 1 . A first data line DL 1  may be interposed between the first and second pixel electrodes PE 21  and PE 22 , and a second data line DL 2  may be interposed between the third and fourth pixel electrodes PE 23  and PE 24 . Hereinafter, enabling the first data line DL 1  and the second data line DL 2  to be disposed neighboring to each other may mean that no data line is interposed between the second and third pixel electrodes PE 22  and PE 23 . The first to fourth pixel electrodes PE 21  to PE 24  may be interposed between an first gate line GL 1  and an second gate line GL 2 . 
     The LCD device according to an exemplary embodiment of the invention may further include first to fourth switching elements TR 1  to TR 4 . As an exemplary embodiment, the first to fourth switching elements TR 1  to TR 4  may be tri-terminal elements such as thin film transistors (“TFTs”). A description will hereinafter be made on the exemplary embodiment in which the first to fourth switching elements TR 1  to TR 4  are TFTs. As an exemplary embodiment, each of the first to fourth switching elements TR 1  to TR 4  may have one electrode which is a source electrode and the other electrode which is a drain electrode. 
     The first switching element TR 1  may include a gate electrode connected to the second gate line GL 2 , one electrode connected to the first data line DL 1 , and the other electrode connected to the first pixel electrode PE 21 . The first switching element TR 1  may provide the first data signal D 1  provided from the first data line DL 1  to the first pixel electrode PE 21  according to the second gate signal G 2  provided from the second gate line GL 2 . The second switching element TR 2  may include a gate electrode connected to the first gate line GL 1 , one electrode connected to the first data line DL 1 , and the other electrode connected to the second pixel electrode PE 22 . The second switching element TR 2  may provide the first data signal D 1  provided from the first data line DL 1  to the second pixel electrode PE 22  according to the first gate signal G 1  provided from the first gate line GL 1 . 
     That is, one electrode of each of the first and second switching elements TR 1  and TR 2  may be connected to the first data line DL 1  so as to share the first data line DL 1 . As described above, the connection structure between the gate line and the first and second switching elements TR 1  and TR 2 , each of which is connected to the first data line DL 1 , is not necessarily limited to those shown in  FIG. 1 . That is, the gate electrode of the first switching element TR 1  may be connected to the first gate line GL 1 , and the gate electrode of the second switching element TR 2  may be connected to the second gate line GL 2 . 
     The third switching element TR 3  may include a gate electrode connected to the first gate line GL 1 , one electrode connected to the second data line DL 2 , and the other electrode connected to the third pixel electrode PE 23 . The third switching element TR 3  may provide the second data signal D 2  provided from the second data line DL 2  to the third pixel electrode PE 23  according to the first gate signal G 1  provided from the first gate line GL 1 . The fourth switching element TR 4  may include a gate electrode connected to the second gate line GL 2 , one electrode connected to the second data line DL 2 , and the other electrode connected to the fourth pixel electrode PE 24 . The fourth switching element TR 4  may provide the second data signal D 2  provided from the second data line DL 2  to the fourth pixel electrode PE 24  according to the second gate signal G 2  provided from the second gate line GL 2 . 
     That is, one electrode of each of the third and fourth switching elements TR 3  and TR 4  may be connected to the second data line DL 2 . As in the first and second switching elements TR 1  and TR 2 , the connection structure between the gate electrode of each of the third and fourth switching elements TR 3  and TR 4  and the gate line is not necessarily limited to those shown in  FIG. 1 . 
     The LCD device according to an exemplary embodiment of the invention may further include the common electrode  170  (refer to  FIG. 6 ) at least partially overlapping the first to fourth pixel electrodes PE 21  to PE 24 . The common electrode  170  may receive a common voltage applied thereto from a separate common line (not shown in the drawings). The common electrode  170  may at least partially overlap the first to fourth pixel electrodes PE 21  to PE 24 . Similarly, the LCD device according to an exemplary embodiment of the invention may further include second to fourth liquid crystal capacitors interposed respectively between the second to fourth pixel electrodes PE 22  to PE 24  and the common electrode  170 . 
     As an exemplary embodiment, at least one slit  171  (refer to  FIG. 4 ) interposed between the second pixel electrode PE 22  and the third pixel electrodes PE 23  may be defined in the common electrode  170 . This will be described later with reference to  FIG. 4 . The first to fourth pixel electrodes PE 21  to PE 24  shown in  FIG. 4  will be denoted by reference numerals  180   a  to  180   d  in  FIGS. 5 to 13 . 
       FIG. 5  is a plan view illustrating in detail a part of components of the display panel shown in  FIG. 4 .  FIG. 6  is a cross sectional view taken along lines I 1 -I 1 ′, I 2 -I 2 ′ and I 3 -I 3 ′ of the plan view of  FIG. 5 .  FIG. 7  is a cross sectional view taken along line I 4 -I 4 ′ of the plan view of  FIG. 5 . The line I 1 -I 1 ′ is used to illustrate the first and second pixel electrodes  180   a  and  180   b  and the first data line DL 1  interposed therebetween, and the line I 2 -I 2 ′ is used to illustrate the second and third pixel electrodes  180   b  and  180   c  and at least one slit  171  interposed therebetween. In addition, the line I 3 -I 3 ′ is used to illustrate the third and fourth pixel electrodes  180   c  and  180   d  and the second data line DL 2  interposed therebetween.  FIG. 7  illustrates a lower display plate  10 . 
     Referring now to  FIG. 5 , the slit  171  may be defined in the common electrode  170 . As an exemplary embodiment, the slit  171  may be defined in the second direction d 2  between the second pixel electrode PE 22  and the third pixel electrode PE 23 . As described above, the first data line DL 1  may be interposed between the first pixel electrode PE 21  and the second pixel electrode PE 22 , and the second data line DL 2  may be interposed between the third pixel electrode PE 23  and the fourth pixel electrode PE 24  (refer to  FIG. 4 ). Thus, no data line is interposed between the second pixel electrode PE 22  and the third pixel electrode PE 23 . The slit  171  of the common electrode  170  may be defined in a region in which no data line is disposed. 
     Furthermore, the slit  171  may not overlap the first data line DL 1  and the second data line DL 2  and other data lines not shown in  FIG. 4 . That is, the slit  171  may extend in the second direction d 2  along which the plurality of data lines DL 1  to DLm (refer to  FIG. 1 ) extend. 
     The connection structure between the second switching element TR 2  and the second pixel electrode  180   b  connected thereto will be described as a representative of the connection structures between the switching elements TR 1  to TR 4  and the pixel electrodes  180   a  to  180   d  connected respectively thereto. 
     Referring to  FIGS. 5 to 7 , the LCD device according to an exemplary embodiment of the invention may include a lower display plate  10 , an upper display plate  20  and a liquid crystal layer  30  interposed therebetween. The lower display plate  10  may face the upper display plate  20 . As an exemplary embodiment, the lower display plate  10  may be sealed to the upper display plate  20 . 
     The lower display plate  10  will hereinafter be described. 
     As an exemplary embodiment, a lower substrate  100  may be a transparent glass substrate, a plastic substrate and the like, and may be an array substrate on which a plurality of switching elements are disposed. 
     The first gate line GL 1 , the second gate line GL 2 , and first to fourth gate electrodes  110   a  to  110   d  may be disposed on the lower substrate  100 . The first gate line GL 1  and the second gate line GL 2  may extend in the first direction d 1  so as to be disposed on the lower substrate  100 . The first and fourth gate electrodes  110   a  and  110   d  may be connected to the second gate line GL 2 . The second and third gate electrodes  110   b  and  110   c  may be connected to the first gate line GL 1 . The first gate line GL 1 , the second gate line GL 2 , and the first to fourth gate electrodes  110   a  to  110   d  may include a single layer, a double layer including at least two, or a triple layer including at least three selected from conductive metals including aluminum (Al), copper (Cu), molybdenum (Mo), chrome (Cr), titanium (Ti), tungsten (W), moly-tungsten(MoW), moly-titanium (MoTi) and copper/moly-titanium (Cu/MoTi), for example. 
     A gate insulation layer  120  may be disposed on the first gate line GL 1 , the second gate line GL 2 , and the first to fourth gate electrodes  110   a  to  110   d . As an exemplary embodiment, the gate insulation layer  120  may include silicon nitride (SiNx), silicon oxide (SiOx) or the like, for example. The gate insulation layer  120  may have a multi-layer structure including at least two insulation layers having different physical properties. 
     A semiconductor layer  130  may be disposed on the gate insulation layer  120 . As an exemplary embodiment, the semiconductor layer  130  may include amorphous silicon, polycrystalline silicon or the like. As another exemplary embodiment, the semiconductor layer  130  may include at least one of oxide semiconductors including In—Ga-Zinc-Oxide (“IGZO”), ZnO, ZnO2, CdO, SrO, SrO2, CaO, CaO2, MgO, MgO2, InO, In2O2, GaO, Ga2O, Ga2O3, SnO, SnO2, GeO, GeO2, PbO, Pb2O3, Pb3O4, TiO, TiO2, Ti2O3 and Ti3O5, for example. 
     The semiconductor layer  130  may at least partially overlap the first data line DL 1  and the second data line DL 2 . Furthermore, as an exemplary embodiment, when a plurality of data lines, first to fourth source electrodes  150   a  to  150   d , first to fourth drain electrodes  151   a  to  151   d  and the semiconductor layer  130  are provided together through a single mask process, the semiconductor layer  130  may be provided beneath the plurality of data lines, the first to fourth source electrodes  150   a  to  150   d , and the first to fourth drain electrodes  151   a  to  151   d . That is, the semiconductor layer  130  may have a shape substantially the same as those of the plurality of data lines, except in a channel region thereof. 
     The semiconductor layer  130  may include a second semiconductor pattern  130   b  which forms the second switching element TR 2 . The second semiconductor pattern  130   b  may at least partially overlap the second gate electrode  110   b.    
     An ohmic contact layer  140  may be disposed on the semiconductor layer  130 . In an exemplary embodiment, the ohmic contact layer  140  may include n+ hydrated amorphous silicon or the like, which is highly doped with n-type impurities such as phosphorus, or including silicide. The ohmic contact layer  140  may be omitted when the semiconductor layer  130  includes an oxide semiconductor. 
     Although the second switching element TR 2  is described above as a representative, the semiconductor layer  130  may further include semiconductor patterns for forming respectively the first, the third and the fourth switching elements TR 1 , TR 3  and TR 4  like the second semiconductor pattern  130   b.    
     The first data line DL 1 , the second data line DL 2 , the second source electrode  150   b  and the second drain electrode  151   b  may be disposed on the ohmic contact layer  140 . That is, as an exemplary embodiment, the first data line DL 1  and the second data line DL 2  may be disposed in the same layer as the second source electrode  150   b  and the second drain electrode  151   b , and may be provided through the same mask process. The first data line DL 1 , the second data line DL 2 , the second source electrode  150   b  and the second drain electrode  151   b  may include a single layer, a double layer including at least two, or a triple layer including at least three selected from conductive metals including aluminum (Al), copper (Cu), molybdenum (Mo), chrome (Cr), titanium (Ti), tungsten (W), moly-tungsten (MoW), moly-titanium (MoTi) and copper/moly-titanium (Cu/MoTi). However, the invention is not limited thereto, and the first data line DL 1 , the second data line DL 2 , the second source electrode  150   b  and the second drain electrode  151   b  may include various metals or conductors. The second source electrode  150   b  may be connected to the first data line DL 1 , and the second drain electrode  151   b  may be electrically connected to the second pixel electrode  180   b  through a second contact hole CNT 2 . The second source electrode  150   b  and the second drain electrode  151   b  may at least partially overlap the second gate electrode  110   b , and spaced apart from each other by a predetermined distance on the same layer. 
     Thus, the second switching element TR 2  may include the second gate electrode  110   b , the second semiconductor pattern  130   b , the second source electrode  150   b  and the second drain electrode  151   b . The second switching element TR 2  may receive a data signal from the first data line DL 1  through the second source electrode  150   b , and provide the received data signal to the second pixel electrode  180   b  through the second drain electrode  151   b  and the second contact hole CNT 2 . However, the second switching element TR 2  is described as a representative herein, the first, the third and the fourth switching elements TR 1 , TR 3  and TR 4  may have substantially the same structure as that of the second switching element TR 2 , since the first, the third and the fourth switching elements TR 1 , TR 3  and TR 4  are provided through a process same as that of the second switching element TR 2 . 
     A first passivation layer  160   a  may be disposed on the gate insulation layer  120  including the second source electrode  150   b  and the second drain electrode  151   b . In an exemplary embodiment, the first passivation layer  160   a  may include an inorganic insulation material such as silicon nitride, silicon oxide and the like. 
     An organic insulation layer  160   b  may be disposed on the first passivation layer  160   a  so as to expose at least a part of the second drain electrode  151   b . The organic insulation layer  160   b  may include a photosensitive material, which eliminates the necessity of using a separate photoresist during patterning of the organic insulation layer  160   b  such as a formation of the second contact hole CNT 2 , thereby improving process efficiency. 
     The common electrode  170  may be disposed on the organic insulation layer  160   b . The common electrode  170  may at least partially overlap the first to fourth pixel electrodes  180   a  to  180   d . The common electrode  170  may cooperate with each of the first to fourth pixel electrodes  180   a  to  180   d  so as to generate an electric field, which adjusts the alignment direction of liquid crystal molecules interposed between the lower display plate  10  and the upper display plate  20 . In an exemplary embodiment, the common electrode  170  may include a transparent conductive material such as indium tin oxide (“ITO”), indium zinc oxide (“IZO”) and the like. 
     A first opening OP 1  may be defined in the common electrode so as to avoid short circuit from the second pixel electrode  180   b . The first opening OP 1  may overlap the second contact hole CNT 2 , and may have a width wider than the width of the second contact hole CNT 2  along the first direction d 1 . Furthermore, a second opening OP 2  may be defined in the common electrode  170  so as to avoid short circuit from the third pixel electrode  180   c . Although the first and second openings OP 1  and OP 2  of the common electrode  170  are described herein, a plurality of openings may be further defined in the common electrode  170  to avoid short circuit from other pixel electrodes. 
     At least one slit  171  may be defined in the common electrode  170 . As described above, at least one slit  171  may be defined so as not to overlap a data line on the lower substrate  100 . That is, the second pixel electrode  180   b  may be connected to the first data line DL 1  through the second switching element TR 2 , and the third pixel electrode  180   c  may be connected to the second data line DL 2  through the third switching element TR 3 , thereby no data line is interposed between the second pixel electrode  180   b  and the third pixel electrode  180   c . At least one slit  171  may be defined in the region in which no data line is disposed. 
     In the LCD device according to an exemplary embodiment of the invention, the slit  171  is defined in the common electrode  170 , thus preventing an electric field from being generated between the common electrode  170  and the second and third pixel electrodes  180   b  and  180   c  disposed at both sides of the slit  171 . Thus, the liquid crystal molecules in the region in which no electric field is generated rotate less or substantially no liquid crystal molecules may exist in the region, thereby reducing transmission of light. Thus, color mixture defects may not occur even when a spacing distance between pixel electrodes is decreased. 
     In the LCD device according to an exemplary embodiment of the invention, color mixture defects may not occur even when a spacing distance between pixel electrodes is decreased, and thus transmittance may be improved by decreasing the spacing distance. Furthermore, in the LCD device according to an exemplary embodiment of the invention, the slit  171  may be defined between the second pixel electrode  180   b  and the third pixel electrode  180   c , that is, in the region which does not overlap the data line, thereby preventing light leakage caused by a fringe field between the data line and the pixel electrodes. 
     The shape, the cross-sectional structure, the number and the like of the slit  171  of the common electrode  170  are not limited as long as the slit  171  is defined in the region in which no data line is disposed. As an exemplary embodiment, the slit  171  may be disposed in parallel to the first data line DL 1  and the second data line DL 2 . As another exemplary embodiment, the slit  171  may have a width wider than that of the data line and narrower than that of a black matrix  200  (refer to  FIG. 6 ). As another exemplary embodiment, the slit  171  may be bent. When the first data line DL 1  and the second data line DL 2  are bent, the slit  171  may have a bent structure similar to the bent structure of the first data line DL 1  and the second data line DL 2 . Thus, a length, a width or the like of the first data line DL 1  and the second data line DL 2  in the extending direction may be adjusted to select a length, a shape, a width or the like of the slit  171 . Furthermore, the slit  171  may overlap the first gate line GL 1  and the second gate line GL 2 , but the invention is not limited thereto. That is, the slit  171  may be interposed between the first gate line GL 1  and the second gate line GL 2 . In an alternative exemplary embodiment, the number of the slit  171  is not necessarily limited to one. This will be described later with reference to  FIGS. 8 and 10 . 
     A second passivation layer  160   c  may be disposed on the common electrode  170 . In an exemplary embodiment, the second passivation layer  160   c  may include an inorganic insulation material such as silicon nitride, silicon oxide and the like. 
     The first to fourth pixel electrodes  180   a  to  180   d  may be disposed on the second passivation layer  160   c . In an exemplary embodiment, the first to fourth pixel electrodes  180   a  to  180   d  may include a transparent conductive material such as ITO, IZO and the like. The first to fourth pixel electrodes  180   a  to  180   d  may overlap at least a part of the common electrode  170 . That is, the first to fourth pixel electrodes  180   a  to  180   d  may overlap at least a part of the common electrode  170  in a vertical direction on the lower substrate  100  so as to generate a horizontal electric field. The first to fourth pixel electrodes  180   a  to  180   d  and the common electrode  170  may be insulated by the second passivation layer  160   c . The second pixel electrode  180   b  may be electrically connected to the second drain electrode  151   b  of the second switching element TR 2  through the second contact hole CNT 2 . 
     A slit may be defined in each of the first to fourth pixel electrodes  180   a  to  180   d . The slit may generate a fringe field between the first to fourth pixel electrodes  180   a  to  180   d  and the common electrode  170  so as to enable liquid crystals to rotate in a certain direction. Referring to  FIG. 4 , as an exemplary embodiment, the slit of each of the first to fourth pixel electrodes  180   a  to  180   d  may extend in the direction substantially the same as the direction in which the first data line DL 1  and the second data line DL 2  extend, and may be bent with an obtuse angle at a center thereof. Upper and lower parts of the first to fourth pixel electrodes  180   a  to  180   d  may be divided into different domains with reference to the bent part of the slit. The shape of the slits and the domains of the first to fourth pixel electrodes  180   a  to  180   d  are not necessarily limited to those shown in  FIG. 5 , and the slits may be defined into various shapes and the domains may have various types. 
     Although not shown in the drawings, a lower alignment layer (not shown) may be disposed on the first to fourth pixel electrodes  180   a  to  180   d . The lower alignment layer may include polyimide and the like, and be disposed on the whole surface of the display area in which the first to fourth pixel electrodes  180   a  to  180   d  are disposed. 
     The upper display plate  20  will now be described. 
     An upper substrate  190  may face the lower substrate  100 . The upper substrate  190  may include transparent glass, plastic or the like, and as an exemplary embodiment, the upper substrate  190  may include a material same as that of the lower substrate  100 . 
     The black matrix  200  may be disposed on the upper substrate  190  so as to prevent light from being transmitted to an area other than the pixel area. As an exemplary embodiment, the black matrix  200  may have a width wider than the width of the slit  171 . The black matrix  200  may be disposed on the upper substrate  190  so as to correspond to the first to fourth switching elements TR 1  to TR 4 , the first gate line GL 1 , the second gate line GL 2 , the first data line DL 1  and the second data line DL 2 . As an exemplary embodiment, the black matrix  200  may include an organic material or a metallic material including chrome, for example. 
     A color filter  210  may be disposed on the black matrix  200  and the upper substrate  190 . More specifically, the color filter  210  may be disposed on the upper substrate  190  corresponding to the pixel area defined by the black matrix  200 . As an exemplary embodiment, the color filter  210  may represent any one of a red color (R), a green color (G) and a blue color (B) to be displayed, for example. 
     Although not shown in the drawings, an overcoating layer (not shown) and an upper alignment layer (not shown) may be disposed on the upper substrate  190 . The overcoating layer may cover and planarize the color filter  210  and the black matrix  200 . 
       FIG. 8  is a plan view illustrating a slit  171 ′ of another exemplary embodiment of the slit  171  shown in  FIG. 5 .  FIG. 9  is a plan view illustrating a slit  171 ″ of another exemplary embodiment of the slit  171  shown in  FIG. 5 .  FIG. 10  is a plan view illustrating a slit  171  of another exemplary embodiment of the slit  171  shown in  FIG. 5 . 
     Referring to  FIG. 8 , the slit  171 ′ may include two subslits. In this case, a region  172  between the subslits may be provided in a location similar to the location of the bent parts of the second and third pixel electrodes  180   b  and  180   c . Furthermore, although the slit  171 ′ having two subslits is depicted in  FIG. 8 , the invention is not necessarily limited thereto. When the slit  171 ′ has a plurality of subslits, the subslits may have a shape, a size and a width which are not the same from one another. 
     Referring to  FIG. 9 , the slit  171 ″ may be interposed between the first gate line GL 1  and the second gate line GL 2 . That is, unlike those shown in  FIG. 5 , the slit  171 ″ extending in the second direction d 2  may not overlap the first gate line GL 1  and the second gate line GL 2  extending in the first direction d 1 . 
     Referring to  FIG. 10 , a plurality of island-shaped slits  171  may be defined in the common electrode  170 . The shape, the size or the like of a unit slit forming the plurality of slits  171  are not limited to those shown in  FIG. 10 . Furthermore, the number of the slits  171  is not limited to those shown in  FIG. 10 . 
       FIG. 11  is a plan view illustrating in detail another exemplary embodiment of first to fourth pixels of the display panel shown in  FIG. 4 .  FIG. 12  is a cross sectional view taken along lines I 1 -I 1 ′, I 2 -I 2 ′ and I 3 -I 3 ′ of the plan view of  FIG. 11 .  FIG. 13  is a cross sectional view taken along line I 4 -I 4 ′ of the plan view of  FIG. 11 . However, duplicate description of the same content as those of the foregoing embodiment described with reference to  FIGS. 5 to 7  will be omitted. 
     Referring to  FIG. 4 , and  FIGS. 11 to 13 , in the LCD device according to another exemplary embodiment of the invention, the common electrode  170  may be disposed on the first passivation layer  160   a.    
     As described above, the first passivation layer  160   a  may include an inorganic insulation material such as silicon nitride, silicon oxide and the like. In an exemplary embodiment, the first passivation layer  160   a  may have a thickness of about 2000 angstroms (Å) to about 4000 Å in a cross-sectional direction, for example. 
     Subsequently, the second passivation layer  160   c  may be disposed on the common electrode  170 . As an exemplary embodiment, a material of the second passivation layer  160   c  and a material of the first passivation layer  160   a  may be the same. That is, the LCD device according to another exemplary embodiment of the invention may not include the organic insulation layer  160   b  shown in  FIG. 4 . The upper surface of the second passivation layer  160   c  on which the first to fourth pixel electrodes  180   a  to  180   d  are disposed is depicted as being uniform in  FIGS. 12 and 13  for convenience of explanation, but the invention is not limited thereto. That is, unlike those shown in  FIGS. 12 and 13 , the second passivation layer  160   c  may have a thickness similar to the thickness of the first passivation layer  160   a.    
     That is, as an exemplary embodiment, each of the first passivation layer  160   a  and the second passivation layer  160   c  may be an inorganic layer having a thickness of about 2000 Å to 4000 Å, for example. Thus, the LCD device according to another exemplary embodiment of the invention shown in  FIGS. 11 to 13  may not include an organic insulation layer having a thickness of about 3 micrometers (μm) to about 4 μm, for example. This eliminates the necessity of forming a separate organic insulation layer, thereby simplifying manufacturing process and providing advantages in terms of cost. 
     The first to fourth pixel electrodes  180   a  to  180   d  may be disposed on the second passivation layer  160   c . Thus, the second contact hole CNT 2  may electrically interconnect the exposed part of the second drain electrode  151   b  and the second pixel electrode  180   b . The first, third and fourth contact holes CNT 1 , CNT 3  and CNT 4  may be substantially similar to the second contact hole CNT 2 , and thereby a detailed description will be omitted. 
     This will be described in detail with reference to  FIGS. 14 to 16 . 
       FIG. 14  illustrates the degree of light leakage when a common electrode is disposed on data lines (a), and the degree of light leakage when no common electrode is disposed on the data lines (b). 
     Referring to  FIG. 14 , the light leakage when no common electrode is disposed on the data lines (b) is more than the light leakage when a common electrode is disposed on data lines (a). When no common electrode is disposed on the data line and thus the data line and the common electrode do not overlap each other, the data line and a pixel electrode are coupled through a non-overlapping region K, thereby generating a fringe field between the data line and the pixel electrode, and the fringe field causes light leakage. Furthermore, as light leakage increases, color mixture defects may also increase. When a spacing distance between pixel electrodes is decreased to improve transmittance, color mixture characteristics may be degraded. 
     Thus, in the LCD device according an exemplary embodiment of the invention, at least one slit  171  may be defined in the common electrode  170 , which may be necessarily formed in a region non-overlapping the data line so as to prevent the light leakage described above. Thus, the light leakage caused by a fringe field can be prevented. 
       FIGS. 15 and 16  comparatively illustrate the transmittance and color mixture defects of the LCD devices according to an exemplary embodiment of the invention and conventional techniques, respectively. 
     Referring to  FIG. 15 , a space between pixel units is darker in the LCD device according to an exemplary embodiment of the invention (b) than in the LCD device according to conventional techniques (a). That is, the LCD device according to an exemplary embodiment of the invention (b) has less light leakage, which means that the LCD device according to an exemplary embodiment of the invention (b) is relatively more excellent in color mixture characteristics. 
     More specifically, referring to table  1  below, since at least one slit  171  is defined in the common electrode  170 , excellent color mixture characteristics may be achieved even when a spacing distance between pixel electrodes is decreased. The decreased spacing distance may result in improved transmittance. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Spacing distance 
                 Spacing distance 
                 Spacing distance 
               
               
                   
                 15.2 μm 
                 8.2 μm 
                 8.2 μm 
               
               
                   
                 (Conventional 
                 (Conventional 
                 (Exemplary 
               
               
                   
                 technique) 
                 technique) 
                 embodiment) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Transmittance 
                 22.8% 
                 24.9% 
                 25.1% 
               
               
                   
               
            
           
         
       
     
       FIGS. 17 and 18  illustrate an arrangement of pixel electrodes of the LCD device according to an exemplary embodiment of the invention. 
     Referring to  FIGS. 5 and 17 , the first pixel electrode PE 21  may represent a red color (R) to be displayed, and the second pixel electrode PE 22  may represent a green color (G) to be displayed. Furthermore, the third and fourth pixel electrodes PE 23  and PE 24  may represent a blue color (B) to be displayed. Thus, as an exemplary embodiment, at least one slit  171  of the common electrode  170  may be interposed between the second pixel electrode PE 22  representing the green color (G) to be displayed and the third pixel electrode PE 23  representing the blue color (B) to be displayed. 
     As described above, the decreased spacing distance between pixel electrodes may cause color mixture defects. In this case, the color mixture defects may become most serious between the green color (G) and the blue color (B). 
     Therefore, at least one slit  171  interposed between the green color (G) and the blue color (B). may be defined in the LCD device according to an exemplary embodiment of the invention To this end, in the LCD device according to an exemplary embodiment of the invention, pixel electrodes may be arranged at a cycle of (R)-(G)-(B)—(B)-(G)-(R), as shown in  FIG. 18 . Referring to  FIG. 18 , the slit  171  of the common electrode  170  may be provided in a region in which no data line is disposed, that is, the slit  171  may be interposed between the second pixel electrode PE 22  and the third pixel electrode PE 23  and between the fourth pixel electrode PE 24  and the fifth pixel electrode PE 25 , for example. In this case, the second to fifth pixel electrodes PE 22  to PE 25  may respectively represent the colors of (G)-(B)-(B)-G) to be displayed, thereby maximizing the degree of improvement in color mixture defects. 
     Although certain exemplary embodiments and implementations are described herein, other exemplary embodiments and modifications will be apparent from this description. Accordingly, the invention is not limited to such exemplary embodiments, but rather to the broader scope of the presented claims and various obvious modifications and equivalent arrangements.