Patent Publication Number: US-2009217521-A1

Title: Display substrate, method of manufacturing the same and display device having the same

Description:
CROSS REFERENCE 
     This patent application is a Divisional application of U.S. application Ser. No. 11/479,629, filed Jun. 30, 2006, which application claims priority to and the benefit of Korean Patent Application No. 2005-58314, filed on Jun. 30, 2005, the disclosure of which are hereby incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display substrate, a method of manufacturing the display substrate, and a display device having the display substrate. More particularly, the present invention relates to a display substrate capable of decreasing the number of elements, a method of manufacturing the display substrate and a display device having the display substrate. 
     2. Description of the Related Art 
     A display device such as a liquid crystal display (LCD) device, an organic light emitting display (OLED) device, etc., in general, includes a display panel for displaying an image and a circuit board for applying driving signals to the display panel. 
     The circuit board changes externally provided image signals into driving signals, which are applied to the display panel through the circuit board. The circuit board includes a flexible printed circuit (FPC) that has a plurality of elements such as a driving integrated circuit (IC), a plurality of capacitors, etc. When a number of elements are integrated on the circuit board, the size of the circuit board is increased, and its structure is relatively complex. 
     SUMMARY OF THE INVENTION 
     The present invention provides a display substrate capable of decreasing the number of elements. 
     The present invention also provides a method of manufacturing the above display substrate. 
     The present invention also provides a display device having the above display substrate. 
     A display substrate in accordance with one embodiment of the present invention includes a substrate, a first capacitor electrode, a dielectric layer, a second capacitor electrode and a transparent conductive electrode. The substrate includes an effective display region and a non-effective display region that surrounds the effective display region. The first capacitor electrode is in the non-effective display region. The dielectric layer is on the first capacitor electrode. The second capacitor electrode is on the dielectric layer corresponding to the first capacitor electrode. The transparent conductive electrode is positioned substantially in the effective display region. 
     A method of manufacturing a display substrate in accordance with one embodiment of the present invention is provided as follows. A metal thin film is formed on a substrate having an effective display region and a non-effective display region. The metal thin film is patterned to form a first capacitor pattern in the non-effective display region. A dielectric layer is formed on the substrate having the first capacitor. A transparent conductive thin film is formed on the dielectric layer. The transparent conductive thin film is patterned to form a second capacitor electrode on the dielectric layer corresponding to the first capacitor electrode in the non-effective display region, and a transparent electrode in the effective display region. 
     A display device includes a first display substrate, a second display substrate, a liquid crystal layer and a circuit board. The first display substrate includes a substrate, a first capacitor electrode, a dielectric layer, a second capacitor electrode and a transparent conductive electrode. The substrate includes an effective display region and a non-effective display region that surrounds the effective display region. The first capacitor electrode is in the non-effective display region. The dielectric layer is on the first capacitor electrode. The second capacitor electrode is on the dielectric layer corresponding to the first capacitor electrode. The transparent conductive electrode is positioned substantially in the effective display region. The second display substrate includes a transparent substrate, a plurality of pixels, a first signal line, a second signal line, and a plurality of third signal lines. The transparent substrate corresponds to the substrate. The pixels are on the transparent substrate, and correspond to the transparent conductive electrode. The first signal line is electrically connected to the transparent conductive electrode. The second signal line is electrically connected to the second capacitor electrode. The third signal lines are electrically connected to associated pixels. The liquid crystal layer is interposed between the first and second display substrates. The circuit board is electrically connected to the first, second, and third signal lines. 
     According to embodiments of the present invention, the capacitor for the circuit board is formed on the display substrate. Electric charge may thus be charged or discharged in the capacitor, thereby decreasing the number of the elements of the circuit board. Therefore, the size of the display device is decreased, and a manufacturing cost of the display device is reduced. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which: 
         FIG. 1  is a plan view showing a display substrate in accordance with one embodiment of the present invention; 
         FIG. 2  is a cross-sectional view taken along a line I-I′ shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view showing a display substrate in accordance with another embodiment of the present invention; 
         FIG. 4  is a cross-sectional view showing a display substrate in accordance with another embodiment of the present invention; 
         FIG. 5  is a cross-sectional view showing a method of manufacturing a display substrate in accordance with one embodiment of the present invention; 
         FIG. 6  is a cross-sectional view showing a first capacitor electrode on the substrate shown in  FIG. 5 ; 
         FIG. 7  is a cross-sectional view showing a dielectric layer such as an organic layer on the first capacitor electrode shown in  FIG. 6 ; 
         FIG. 8  is a cross-sectional view showing a transparent conductive thin film on the substrate shown in  FIG. 7 ; 
         FIG. 10  is a cross-sectional view showing a method of manufacturing a display substrate in accordance with another embodiment of the present invention; and 
         FIG. 10  is a cross-sectional view showing a method of manufacturing a display substrate in accordance with another embodiment of the present invention; and 
         FIG. 11  is a cross-sectional view showing a display device in accordance with one embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully describe the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. 
     It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element 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. 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. 
     It will be understood that, although the terms first, second, third 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 only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. Use of the term “first” does not imply that a “second” or other additional element is required. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures 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. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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. It will be further understood that the terms “includes,” “including,” “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of the invention are described herein with reference to schematic illustrations of idealized embodiments (and intermediate structures) of the invention. 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, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from 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 figures 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 limit the scope of the invention. 
     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 invention belongs. It will be further understood that 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, the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a plan view showing a display substrate in accordance with one embodiment of the present invention.  FIG. 2  is a cross-sectional view taken along a line I-I′shown in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the display substrate  100  includes a substrate  10 , a first capacitor electrode  20 , a dielectric layer  30 , a second capacitor electrode  40  and a transparent electrode  50 . 
     For example, the substrate  10  includes a transparent glass substrate. The substrate  10  may have a substantially quadrangular shape when viewed on a plane. 
     The substrate  10  includes an effective display region EDR and a non-effective display region NEDR. For example, the non-effective display region NEDR may correspond to a peripheral portion of the substrate  10 , and may have a band shape. In  FIGS. 1 and 2 , the non-effective display region NEDR of substrate  10  is positioned on the peripheral region of the substrate  10  and has a closed loop shape. The non-effective display region NEDR surrounds the effective display region EDR. 
     The first capacitor electrode  20  is on the substrate  10 . The dielectric layer  30  is on the first capacitor electrode  20 . The second capacitor electrode  40  is on the dielectric layer  30 . The first capacitor electrode  20 , the dielectric layer  30  and the second capacitor electrode  40  form a capacitor, and an electric charge is stored in the capacitor. 
     The first capacitor electrode  20  is in the non-effective display region NEDR of the substrate  10 . For example, the first capacitor electrode  20  may be positioned along the non-effective display region NEDR A width W 1  of the first capacitor electrode  20  may be substantially same as a width W 2  of the non-effective display region NEDR. 
     The first capacitor electrode  20  may have a closed loop shape that is substantially the same as the non-effective display region NEDR. The first capacitor electrode  20  may be formed using a material including a metal. Examples of metals that may be used for the first capacitor electrode  20  include chromium, chromium oxide, etc. 
     The dielectric layer  30  is on the first capacitor electrode  20 . The dielectric layer  30  may include a dielectric material. Examples of dielectric materials that may be used for the dielectric layer  30  include silicon oxide, silicon nitride, organic materials, etc. The dielectric layer  30  functions as a dielectric material to store the electric charge applied through the first and second capacitor electrodes  20  and  40 . 
     The transparent electrode  50  may be positioned substantially in the effective display region EDR. That is, most of transparent electrode  50  may be positioned in the effective display region EDR, while one or more portions of transparent electrode  50  may extend into the non-effective display region NEDR, as shown in  FIG. 1 . The transparent electrode  50  may include transparent conductive material. Examples of transparent conductive material that, may be used for the transparent electrode  50  include indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. 
     In operation, a driving signal for displaying an image is applied to the transparent electrode  50 . A charging signal or a discharging signal is applied to the second capacitor electrode  40 . The transparent electrode  50  is spaced apart from the second capacitor electrode  40 . 
     The driving signal may be applied to the transparent electrode  50  through a conductive connector (not shown). However, when the conductive connector (not shown) is formed in the effective display region EDR, the opening ratio and luminance may be decreased. The image display quality of the display substrate may thus be compromised. 
     In the embodiment illustrated in  FIGS. 1 and 2 , however, the transparent electrode  50  includes a protruded portion  55  that protrudes from the effective display region EDR into the non-effective display region NEDR. The second capacitor electrode  40  that corresponds to the protruded portion  55  may include a recessed portion  47  that is spaced apart from the protruded portion  55  when viewed on a plane. 
     That is, the transparent electrode  50  includes the protruded portion  55  that is protruded from the effective display region EDR into the non-effective display region NEDR, and the second capacitor electrode  40  includes a recessed portion  47  that does not overlap with the protruded portion  55 . 
     That is, the transparent electrode  50  includes the protruded portion  55  that is protruded from the effective display region EDR into the non-effective display region NEDR, and the second capacitor electrode  40  includes a recessed portion  47  that does not overlap with the protruded portion  55 . 
     A black matrix  60  and a color filter  70  may also be formed in the effective display region EDR of the display substrate  100 . 
     The black matrix  60  is formed in the effective display region in a lattice shape. The black matrix  60  includes an opaque material. Examples of opaque materials that can be used for the black matrix  60  include chromium, chromium oxide, etc. 
     The black matrix  60  is formed on substantially the same layer as the first capacitor electrode  20 . In  FIGS. 1 and 2 , the charging and discharging signals are applied to the first capacitor electrode  20 , and the black matrix  60  is spaced apart from the first capacitor electrode  20 . 
     The color filter  70  is formed on the effective display region EDR of the substrate  10  that is exposed through openings of the black matrix  60 . For example, the color filter  70  may include a red color filter, a green color filter, and a blue color filter. 
       FIG. 3  is a cross-sectional view showing a display substrate in accordance with another embodiment of the present invention. The display substrate of  FIG. 3  is same as in  FIGS. 1 and 2 , except for dielectric layer  35 . Thus, the same reference numerals will be used to refer to the same or like parts as those described in  FIGS. 1 to 2  and further explanation may be omitted. 
     Referring to  FIG. 3 , the dielectric layer  35  is formed in an effective display region EDR and a non-effective display region NEDR, and the dielectric layer  35  covers the first capacitor electrode  20 . The dielectric layer  35  may be formed using a spin coating method. The dielectric layer  35  includes a dielectric material. Examples of dielectric materials that can be used for the dielectric layer  35  include silicon oxide, silicon nitride, etc. A color filter  70  is positioned on the dielectric layer  35 , and a transparent electrode  50  is positioned on the color filter  70 . 
       FIG. 4  is a cross-sectional view showing a display substrate in accordance with another embodiment of the present invention. The display substrate of  FIG. 4  is same as in  FIGS. 1 and 2  except for dielectric layer  75 . Thus, the same reference numerals will be used to refer to the same or like parts as those described in  FIGS. 1 to 2  and any further explanations will be omitted. 
     Referring to  FIG. 4 , the dielectric layer  75  is in a non-effective display region NEDR between the first and second capacitor electrodes  20  and  40 . The dielectric layer  75  may be formed through a process of manufacturing a color filter  70 . That is, the dielectric layer  75  includes same material as that of the color filter  70 . Since the a material of color filter  70  functions as the dielectric layer  75 , an additional material for the dielectric layer  75  need not be provided, so that the structure of display substrate  100  is simplified. 
     Method of Manufacturing Display Substrate 
       FIG. 5  is a cross-sectional view showing a method of manufacturing a display substrate in accordance with one embodiment of the present invention. 
     Referring to  FIG. 5 , an effective display region EDR and a non-effective display region NEDR that surrounds the effective display region EDR are indicated for a substrate  200 . The substrate  200  may be a transparent glass substrate. 
       FIG. 6  is a cross-sectional view showing a first capacitor electrode  215  on the substrate shown in  FIG. 5 . 
       FIG. 6  is a cross-sectional view showing a first capacitor electrode  215  on the substrate shown in  FIG. 5 . 
     Referring to  FIGS. 5 and 6 , metal layer  210  on substrate  200  is patterned to form a first capacitor electrode  215 , using a photolithography process. 
     In particular, the metal layer  210  is cleaned, and a photoresist layer is coated on the metal layer  210 . The photoresist layer is exposed and developed to form a photoresist pattern, which acts as an etch mask. The metal layer  210  is partially etched according to the photoresist pattern to form the first capacitor electrode  215  on the substrate  200 . 
     The first capacitor electrode  215  may be formed in the non-effective display region NEDR. The first capacitor electrode  215 , a dielectric layer, and a second capacitor electrode form a capacitor to store an electric charge. In addition, the first capacitor electrode  215  may block light that leaks from one or more pixels of the substrate  200 , so that the first capacitor electrode  215  may function as an edge black matrix of an LCD device. 
       FIG. 7  is a cross-sectional view showing a dielectric layer such as an organic layer on the first capacitor electrode shown in  FIG. 6 . 
     Referring to  FIG. 7 , a shadow mask  220   a  is aligned on the effective display region EDR. The shadow mask  220   a  has substantially the same shape and size as the effective display region EDR. Alternatively, the shadow mask  220   a  may have a larger size than the effective display region EDR. 
     A dielectric layer  220  is deposited on the first capacitor electrode  215  through the shadow mask  220   a  to form the dielectric layer  220 . Examples of dielectric materials that can be used for the dielectric layer  220  include silicon oxide, silicon nitride, etc. 
     Alternatively, the dielectric layer  220  may be formed through a deposition process and a photolithography process. 
     That is, a dielectric thin film may first be formed in the effective display region EDR and the non-effective display region NEDR of the substrate  200  having the first capacitor electrode  215  using a spin coating process, a slit coating process, a chemical vapor deposition process, a sputtering process, etc. 
     A photoresist pattern (not shown) is formed on the dielectric thin film corresponding to the first capacitor electrode  215 . 
     The dielectric thin film is partially etched using the photoresist pattern as an etching mask to etch the dielectric material in the effective display region EDR, leaving the dielectric layer  220  in the non-effective display region NEDR. 
     Alternatively, an organic layer (not shown) may be formed on an entire of the substrate  200  through a spin coating process, a slit coating, a sputtering process, etc. In the effective display region EDR, the organic layer may be used to provide the color filter, while in the non-effective display region NEDR, the organic layer may function as the dielectric layer for the capacitor described herein. 
       FIG. 8  is a cross-sectional view showing a transparent conductive thin film on the substrate shown in  FIG. 7 . 
     Referring to  FIG. 8 , a transparent conductive thin film  230  is formed in the effective display region EDR and the non-effective display region NEDR of the substrate through a chemical vapor deposition process, a sputtering process, etc. Examples of transparent conductive materials that can be used for the transparent conductive thin film  230  include indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide, etc. 
       FIG. 9  is a cross-sectional view showing a second capacitor electrode and a transparent electrode formed by patterning the transparent conductive thin film shown in  FIG. 8 . 
     Referring to  FIG. 9 , a photoresist thin film (not shown) is formed on the substrate  200  having the transparent conductive thin film  230  through a spin coating process, a slit coating process, etc. 
     A pattern mask is aligned on the photoresist thin film (not shown), and the photoresist thin film (not shown) is exposed through the pattern mask. The photoresist thin film (not shown) is then developed to form a photoresist pattern (not shown) on the transparent conductive thin film  230 . For example, the photoresist pattern (not shown) may be between the effective display region EDR and the non-effective display region NEDR. 
     The transparent conductive thin film  230  is etched through the photoresist pattern as an etching mask to form the second capacitor electrode  235  and a transparent electrode  237  in the non-effective display region NEDR and the effective display region EDR, respectively. 
     The second capacitor electrode  235  is spaced apart from the transparent electrode  237  by a predetermined distance. A protruded portion protrudes from the transparent electrode  237  in the effective display region EDR into the non-effective display region NEDR. In addition, a recessed portion is formed in the second capacitor electrode  235  corresponding to the protruded portion, and spaced apart from the protruded portion. 
       FIG. 10  is a cross-sectional view showing a method of manufacturing a display substrate in accordance with another embodiment of the present invention. Some of the method of manufacturing the display substrate of  FIG. 10  is the same as in  FIGS. 5 to 9 . Thus, the same reference numerals will be used to refer to the same or like parts as those described in  FIGS. 5 to 9  and any further explanations will be omitted. 
     Referring to  FIG. 10 , a black matrix pattern  217  may be formed from a same layer as a first capacitor electrode  215  that is in a non-effective display region NEDR. The black matrix pattern  217  is in an effective display region EDR, and has a matrix shape. 
     A color filter  219  is formed in the effective display region EDR. The color filter  219  corresponds to an opening of the black matrix pattern  217 . The color filter  219  includes a red color filter, a green color filter and a blue color filter. 
     Display Device 
       FIG. 11  is a cross-sectional view showing a display device in accordance with one embodiment of the present invention. 
     Referring to  FIG. 11 , the display device  500  includes a first display substrate  100 , a second display substrate  300  and a liquid crystal layer  400 . 
     The first display substrate  100  includes a substrate  10 , a first capacitor electrode  20 , a dielectric layer  30 , a second capacitor electrode  40  and a common electrode  50 . The first display substrate  100  may further include a black matrix pattern  60  and a color filter  70 . 
     For example, the substrate  10  includes a transparent glass substrate. The substrate  10  may have a substantially quadrangular shape when viewed on a plane. 
     The substrate  10  includes an effective display region EDR and a non-effective display region NEDR. For example, the non-effective display region NEDR corresponds to a peripheral portion of the substrate  10 , and has a band shape. The non-effective display region NEDR may be on the peripheral region of the substrate  10  and may have a closed loop shape. The non-effective display region NEDR substantially surrounds the effective display region EDR. 
     The first capacitor electrode  20  is on the substrate  10 . The dielectric layer  30  is on the first capacitor electrode  20 . The second capacitor electrode  40  is on the dielectric layer  30 . The first capacitor electrode  20 , the dielectric layer  30  and the second capacitor electrode  40  form a capacitor, and an electric charge is stored in the capacitor. 
     The first capacitor electrode  20  is in the non-effective display region NEDR of the substrate  10 . For example, the first capacitor electrode  20  may be arranged along the non-effective display region NEDR. The first capacitor electrode  20  may have the closed loop shape that is substantially the same as the non-effective display region NEDR. The first capacitor electrode  20  may include a metal. Examples of metals that can be used for the first capacitor electrode  20  include chromium, chromium oxide, etc. 
     The dielectric layer  30  is on the first capacitor electrode  20 . The dielectric layer  30  may include a dielectric material. Examples of dielectric materials that can be used for the dielectric layer  30  include silicon oxide, silicon nitride, etc. The dielectric layer  30  functions as a dielectric material that stores the electric charge that is applied through the first and second capacitor electrodes  20  and  40 . 
     The second capacitor electrode  40  is on the dielectric layer  30 , which may comprise an organic material. The second capacitor electrode  40  may include a transparent conductive material. Examples of transparent conductive materials that can be used for the second capacitor electrode  40  include indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. 
     The common electrode  50  may be in the effective display region EDR. The common electrode  50  may include the transparent conductive material. Examples of transparent conductive materials that can be used for the common electrode  50  include indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), etc. 
     In operation, a driving signal for displaying an image is applied to the common electrode  50 . A charging signal or a discharging signal is applied to the second capacitor electrode  40 . The common electrode  50  is spaced apart from the second capacitor electrode  40 . 
     The driving signal may be applied to the common electrode  50  through a conductive connector (not shown). However, when the conductive connector (not shown) is formed on the effective display region EDR, an opening rate and a luminance may be decreased and the image display quality of the display substrate may be compromised. 
     In  FIG. 11 , however, the common electrode  50  includes a protruded portion that protrudes from the effective display region EDR into the non-effective display region NEDR. The second capacitor electrode  40  that corresponds to the protruded portion may include a recessed portion that is spaced apart from the protruded portion when viewed on a plane. 
     A black matrix pattern  60  may be formed in the effective display region EDR of the display substrate  100  as a matrix shape. Examples of metals that can be used for the black matrix pattern  60  include chromium, chromium oxide, etc. 
     The black matrix pattern  60  may be formed from substantially the same layer as the first capacitor electrode  20 . The charging and discharging signals are applied to the first capacitor electrode  20 , and the black matrix  60  is spaced apart from the first capacitor electrode  20 . 
     The color filter  70  is formed on the effective display region EDR of the substrate  10  that is exposed through openings of the black matrix pattern  60 . For example, the color filter  70  may include a red color filter, a green color filter and a blue color filter. 
     An alignment layer (not shown) having a plurality of alignment grooves may be formed on the common electrode  50 . 
     The second display substrate  300  includes a transparent substrate  310 , a thin film transistor (TFT)  320  and a pixel electrode  330  that is electrically connected to a drain electrode (not shown) of the thin film transistor  320 . The drain electrode (not shown) may be an output electrode of the thin film transistor  320 . 
     In  FIG. 11 , a plurality of thin film transistors  320  is arranged on the transparent substrate  310  in a matrix shape. For example, when a resolution of the display device  500  is 1024.times.768, the number of the thin film transistors  320  is about 1024.times.768.times.3. 
     The pixel electrodes  330  of thin film transistors  320  correspond to the common electrode  50  of the first display substrate  100 , and are electrically connected to the associated thin film transistors  320 . A plurality of signal lines (not shown) is electrically connected to the thin film transistors  320 . 
     A circuit board  360  is electrically connected to the second display substrate  300 . The circuit board  360  applies a first driving signal to the signal lines (not shown), and applies a second driving signal and a third driving signal to the second capacitor electrode  40  of the first display substrate  100  and the common electrode  50 , respectively. 
     A first conductive connector  370  is positioned between the second capacitor electrode  40  of the first display substrate  100  and the second display substrate  300  to transmit the second driving signal to the second capacitor electrode  40 . In addition, a second conductive connector  380  is positioned between the common electrode  50  of the first display substrate  100  and the second display substrate  300  to transmit the third driving signal to the common electrode  50 . 
     Each of the first and second conductive connectors  370  and  380  may include a synthetic resin body and a metal thin film on the synthetic resin body. Alternatively, each of the first and second conductive connectors  370  and  380  may include a metal body. Examples of metals that can be used for the first and second conductive connectors  370  and  380  include gold, silver, etc. 
     The second driving signal is applied from the second display substrate  300  to the second capacitor electrode  40  through the first conductive connector  370  so that an electric charge is stored between the first and second capacitor electrodes  20  and  40 . The first and second capacitor electrodes  20  and  40  and the dielectric layer  30  form the capacitor. In addition, the stored electric charge may be discharged so that an electric charge is applied to the circuit board  360 . 
     The liquid crystal layer  400  is interposed between the first and second display substrates  100  and  300 . Liquid crystal molecules of the liquid crystal layer  400  vary their arrangement in response to an electric field applied between the pixel electrode  330  and the common electrode  50 , so that the light transmittance of the liquid crystal layer  400  may be changed, thereby displaying an image. 
     In  FIG. 11 , the capacitor is formed on the first display substrate  100 . Alternatively, the capacitor may be formed on the second display substrate  300 . 
     According to embodiments of the present invention, the capacitor for the circuit board is formed on the display substrate so that the electric charge may be charged or discharged in the capacitor, thereby decreasing the number of the elements of the circuit board. 
     This invention has been described with reference to the exemplary embodiments. It is evident, however, that many alternative modifications and variations will be apparent to those having skill in the art in light of the foregoing description. Accordingly, the present invention embraces all such alternative modifications and variations as fall within the spirit and scope of the appended claims.