Patent Publication Number: US-8982113-B2

Title: LCD panel and method for controlling voltage thereof

Description:
FIELD OF THE INVENTION 
     The present invention relates to a liquid crystal display (LCD) technology, and especially to an LCD panel and a method for controlling a voltage thereof. 
     BACKGROUND OF THE INVENTION 
     With a growing popularity of LCDs, quality of the LCDs is also increasing. 
     Referring to  FIG. 1 ,  FIG. 1  is a driving circuit diagram illustrating a liquid crystal display (LCD) panel in the prior art. The LCD panel includes pixel electrodes  101 , gate lines  102 , data lines  103 , pixel capacitors  104 , and storage capacitors  105 . 
     After a gate voltage (not shown) of a thin film transistor (TFT) is turned on, an electrical signal is written into the pixel electrode  101  via the data line  103 , thereby providing a filled voltage signal for the pixel electrode  101 . Then, the gate voltage of the TFT is turned off, and the pixel electrode  101  maintains a constant voltage. 
     In driving the TFT, the same Vcom is applied to the pixel capacitor  104  and the storage capacitor  105 . However, when the gate voltage of the TFT is turned off, the voltage on the gate line  102  is switched from Vg_on to Vg_off. Referring to  FIG. 2 , the voltage of the pixel electrode  101  is affected by the capacitors to generate a feed-through voltage drop ΔVp due to a redistribution of electric charges. 
     The voltage drop ΔVp makes voltages of positive and negative polarities that originally were symmetrical with respect to the Vcom being asymmetrical. The voltage differences generate a flicker when driving using the voltages of the positive and negative polarities, resulting in a crosstalk, affecting the user&#39;s viewing. 
     Therefore, there is a problem of the crosstalk resulting form the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps. The problem remains to be solved in the LCD technology. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide an LCD panel which can solve the problem of the crosstalk resulting form the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps. 
     To achieve the foregoing objective, an LCD panel constructed in the present invention includes: a gate driver, a source driver, a plurality of gate lines and a plurality of data lines. The gate lines and the data lines define a plurality of pixel units, and each pixel unit includes a TFT, a common electrode, and a pixel electrode. The data line is utilized to charge the pixel electrode. 
     The LCD panel further comprises a common electrode line, the common electrode line coupled to the common electrode. The common electrode line is utilized to alternately provide a first common electrode voltage and a second common electrode voltage to the common electrode, so that the charge voltage of the pixel electrode still approaches a target voltage by which the data line charges the pixel electrode when a gate voltage of the TFT is turned off. 
     The data line, a gate of TFT, and the common electrode line herein control each of responsive voltages according to sequential order of time points A 1 , B 1 , and C 1 . At the time point A 1 , the data line is utilized to provide the pixel voltage to the pixel unit. At the time point B 1 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode, and the common electrode line is utilized to provide the first common electrode voltage to the common electrode. At the time point C 1 , the gate voltage of the TFT is turned off, and the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     To achieve the foregoing objective, an LCD panel further provided in the present invention includes a gate driver, a source driver, a plurality of gate lines and a plurality of data lines. The gate lines and the data lines define a plurality of pixel units, and each pixel unit includes a TFT, a common electrode, and a pixel electrode. The data line is utilized to charge the pixel electrode. The LCD panel further comprises a common electrode line, the common electrode line coupled to the common electrode. The common electrode line is utilized to alternately provide a first common electrode voltage and a second common electrode voltage to the common electrode, so that the charge voltage of the pixel electrode still approaches a target voltage by which the data line charges the pixel electrode when a gate voltage of the TFT is turned off. 
     The data line, a gate of TFT, and the common electrode line herein control each of responsive voltages according to sequential order of time points A 2 , B 2 , C 2 , and D 2 . At the time point A 2 , the data line is utilized to provide the pixel voltage to the pixel unit, and the common electrode line is utilized to provide the first common electrode voltage to the common electrode. At the time point B 2 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode. At the time point C 2 , the gate voltage of the TFT is turned off. At the time point D 2 , the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     In the LCD panel of the present invention, the second common electrode voltage is greater than the first common electrode voltage; the first common electrode voltage and the second common electrode voltage are generated alternately in a fixed period of time, which is a duration of scanning a frame. 
     Another objective of the present invention is to provide an LCD panel which can solve the problem of the crosstalk resulting form the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps. 
     To achieve the foregoing objective, an LCD panel constructed in the present invention includes a gate driver, a source driver, a plurality of gate lines and a plurality of data lines. The gate lines and the data lines define a plurality of pixel units, and each pixel unit includes a TFT, a common electrode, and a pixel electrode. The data line is utilized to charge the pixel electrode. The LCD panel further comprises a common electrode line, the common electrode line coupled to the common electrode. 
     The common electrode line is utilized to provide alternating common electrode voltages to the common electrode, so that the charge voltage of the pixel electrode still approaches a target voltage by which the data line charges the pixel electrode when a gate voltage of the TFT is turned off. 
     In the LCD panel of the present invention, the common electrode voltages comprises a first common electrode voltage and a second common electrode voltage, and the second common electrode voltage is larger than the first common electrode voltage. 
     The first common electrode voltage and the second common electrode voltage are generated alternately in a fixed period of time, which is a duration of scanning a frame. 
     In the LCD panel of the present invention, respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to time points A 1 , B 1 , and C 1 , which are sequentially separated by intervals. 
     At the time point A 1 , the data line is utilized to provide the pixel voltage to the pixel unit. 
     At the time point B 1 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode, and the common electrode line is utilized to provide the first common electrode voltage to the common electrode. 
     At the time point C 1 , the gate voltage of the TFT is turned off, and the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     In the LCD panel of the present invention, respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to time points A 2 , B 2 , C 2 , and D 2 , which are sequentially separated by intervals. 
     At the time point A 2 , the data line is utilized to provide the pixel voltage to the pixel unit, and the common electrode line is utilized to provide the first common electrode voltage to the common electrode. 
     At the time point B 2 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode. 
     At the time point C 2 , the gate voltage of the TFT is turned off. 
     At the time point D 2 , the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     In the LCD panel of the present invention, the data line, the gate of TFT and the common electrode line are controlled according to time points A 3 , B 3 , C 3 , D 3 , and E 3 , which are sequentially separated by intervals; 
     At the time point A 3 , the data line is utilized to provide the pixel voltage to the pixel unit. 
     At the time point B 3 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode. 
     At the time point C 3 , the common electrode line is utilized to provide the first common electrode voltage to the common electrode. 
     At the time point D 3 , the gate voltage of the TFT is turned off. 
     At the time point E 3 , the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     Another objective of the present invention is to provide a method for controlling a voltage of an LCD panel, thereby solving the problem of the crosstalk resulting form the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps. 
     To achieve the foregoing objective, a method for controlling a voltage of an LCD panel is constructed in the present invention. The LCD panel includes a gate driver, a source driver, a plurality of gate lines and a plurality of data lines. The gate lines and the data lines define a plurality of pixel units, and each pixel unit comprises a TFT, a common electrode, and a pixel electrode. The method includes the steps of: providing a common electrode line for coupling to the common electrode; charging the pixel electrode through the data line; and providing alternating common electrode voltages to the common electrode through the common electrode line, so that the charge voltage of the pixel electrode still approaches a target voltage by which the data line charges the pixel electrode when a gate voltage of the TFT is turned off. 
     In the method for controlling the voltage of the LCD panel of the present invention, the common electrode voltages comprises a first common electrode voltage and a second common electrode voltage, and the second common electrode voltage is larger than the first common electrode voltage. 
     The first common electrode voltage and the second common electrode voltage are generated alternately in a fixed period of time, which is a duration of scanning a frame. 
     In the method for controlling the voltage of the LCD panel of the present invention, respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to time points A 1 , B 1 , and C 1 , which are sequentially separated by intervals. 
     At the time point A 1 , the data line provides the pixel voltage to the pixel unit. 
     At the time point B 1 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode, and the common electrode line begins to provide the first common electrode voltage to the common electrode. 
     At the time point C 1 , the gate voltage of the TFT is turned off, and the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     In the method for controlling the voltage of the LCD panel of the present invention, respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to time points A 2 , B 2 , C 2 , and D 2 , which are sequentially separated by intervals. 
     At the time point A 2 , the data line provides the pixel voltage to the pixel unit, and the common electrode line begins to provide the first common electrode voltage to the common electrode. 
     At the time point B 2 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode. 
     At the time point C 2 , the gate voltage of the TFT is turned off. 
     At the time point D 2 , the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     In the method for controlling the voltage of the LCD panel of the present invention, the data line, a gate of TFT and the common electrode line are controlled according to time points A 3 , B 3 , C 3 , D 3 , and E 3 , which are sequentially separated by intervals. 
     At the time point A 3 , the data line provides the pixel voltage to the pixel unit. 
     At the time point B 3 , the gate voltage of the TFT is turned on, and the data line begins to charge the pixel electrode. 
     At the time point C 3 , the common electrode line is utilized to provide the first common electrode voltage to the common electrode. 
     At the time point D 3 , the gate voltage of the TFT is turned off. 
     At the time point E 3 , the common electrode line is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode. 
     Compared with the prior art, the problem resulting from the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps is solved, so the flicker of image is reduced and the display quality of the product is improved. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a driving circuit diagram illustrating a liquid crystal display in the prior art; 
         FIG. 2  is a schematic drawing illustrating a voltage change of gate line of the LCD in the prior art; 
         FIG. 3  is a circuit diagram illustrating an LCD panel according to a preferred embodiment of the present invention; 
         FIG. 4  is a schematic drawing illustrating waveform of the LCD panel according to a first preferred embodiment of the present invention; 
         FIG. 5  is a schematic drawing illustrating waveform of the LCD panel according to a second preferred embodiment of the present invention; 
         FIG. 6  is a schematic drawing illustrating waveform of the LCD panel according to a third preferred embodiment of the present invention; and 
         FIG. 7  is a flow chart illustrating a method for controlling the voltage of the LCD panel according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Descriptions of the following embodiments refer to attached drawings which are utilized to exemplify specific embodiments. 
       FIG. 3  is a circuit diagram illustrating an LCD panel according to a preferred embodiment of the present invention. 
     The LCD panel provided by the present invention includes a gate driver, a source driver (not shown), a plurality of gate lines  202  and data lines  203 . The gate lines  202  and the data lines  203  define a plurality of pixel units  201 . Each of the pixel units  201  includes a pixel capacitor  2011 , a storage capacitor  2012 , a pixel electrode  2013 , and a common electrode  2014 . 
     The LCD panel provided by the present invention further includes a TFT (not shown). TFT includes a gate, a source, and a drain. 
     The LCD panel provided by the present invention further includes a common electrode line  204 , which coupled to the common electrode  2014 . 
     The data line  203  herein is utilized to charge the pixel electrode  2013 ; also the pixel capacitor  2011  and the storage capacitor  2012  are charged at the same time. 
     The common electrode line  204  is utilized to provide alternating common electrode voltages to the common electrode  2014  so that a voltage of the pixel electrode  2013  still approaches a target voltage by which the data line  203  charges the pixel electrode  2013  when a gate voltage of the TFT is turned off. 
     In the present invention, that the voltage of the pixel electrode  2013  still approaches the target voltage by which the data line  203  charges the pixel electrode  2013  indicates that a difference between the target voltage and the voltage of the pixel electrode  2013  after charging is infinitely small or even the same. More specifically, the difference value between the target voltage and the voltage of the pixel electrode  2013  after charging is within a preset threshold range, such as 0.01V to 0.03V. 
     Preferably, the alternating common electrode voltages comprise a first common electrode voltage Vcom_T 1  and a second common electrode voltage Vcom_T 2 . The first common electrode voltage Vcom_T 1  is smaller than the second common electrode voltage Vcom_T 2 . 
     The first common electrode voltage Vcom_T 1  and the second common electrode voltage Vcom_T 2  are generated alternately in a fixed period of time, which is a duration of scanning a frame. The turn-on duration T 1  corresponds to the first common electrode voltage Vcom_T 1 , and the turn-off duration T 2  corresponds into the second common electrode voltage Vcom_T 2 . 
       FIG. 4  is a schematic drawing illustrating waveform of the LCD panel according to a first preferred embodiment of the present invention. 
     Referring to  FIG. 3  and  FIG. 4 , in the embodiment shown in  FIG. 4 , respective voltages of the data line  203 , the gate of TFT, and the common electrode line  204  are controlled according to sequential order of time points A 1 , B 1 , and C 1 , which are sequentially separated by intervals. 
     The time point A 1  at which the data line  203  provides the pixel voltage to the pixel unit  201  is earlier than the time point B 1  at which the gate voltage Vg of the TFT is turned on. 
     At the time point B 1 , the gate voltage Vg of the TFT is turned on; meanwhile, the common electrode line  204  provides the first common electrode voltage Vcom_T 1  to the common electrode  2014 , and the data line  203  begins to charge the pixel electrode  2013  at the same time. The target voltage of the data line  203  charging the pixel electrode  2013  is Vd. After charging, the voltage of the pixel electrode  2013  is Vs, in which Vs=Vd. A voltage difference between the pixel electrode  2013  and the common electrode  2014  is Vd−Vcom_T 1 . The electric charges between the pixel electrode  2013  and the common electrode  2014  indicate Q=C 1 *(Vs−Vcom_T 1 ). 
     At the time point C 1 , the gate voltage of the TFT is turned off, and the common electrode line  204  provides the second common electrode voltage Vcom_T 2  to the common electrode  2014 . In accordance a charge conservation general principle as follow: 
     C 1 *(Vs−Vcom_T 1 )=C 1 *(V′s−Vcom_T 2 ), because Vcom_T 2 &gt;Vcom_T 1 , V′s&gt;Vs. Meanwhile, when the gate voltage Vg of the TFT is turned off, the voltage V′s of the pixel electrode  2013  which is affected by the capacitor has a voltage drop ΔV such that the voltage of the pixel electrode  2013  becomes V′s−ΔV. Due to V′s&gt;V′s−ΔV&gt;Vs=Vd, the final voltage V′s−ΔV of the pixel electrode  2013  compared to V′s is closer to the target voltage Vd by which the data line  203  charges the pixel electrode  2013 . 
     Referring to  FIG. 5 ,  FIG. 5  is a schematic drawing illustrating waveform of the LCD panel according to a second preferred embodiment of the present invention. 
     Referring to  FIG. 3  and  FIG. 5 , in the embodiment shown in  FIG. 5 , respective voltages of the data line  203  a gate of TFT and the common electrode line  204  are controlled according to sequential order of time points A 2 , B 2 , C 2 , and D 2 , which are sequentially separated by intervals. 
     The time point A 2  at which the data line  203  provides the pixel voltage to the pixel unit  201  is earlier than the time point B 2  at which the gate voltage Vg of the TFT is turned on. 
     At the time point A 2 , the gate voltage Vg of the TFT is not turned on, and the common electrode line  204  alters the voltage of the common electrode  2014  to the first common electrode voltage Vcom_T 1 . In accordance with charge conservation:
 
 C 1*( V com —   T 2− Vs )= C 1*( V com —   T 1− V′s ), because  V com —   T 2&gt; V com —   T 1,  Vs&gt;V′s.  
 
     At the time point B 2 , the gate voltage of the TFT is turned on, and the data line  203  begins to charge the pixel electrode  2013 . The target voltage of the data line  203  charging the pixel electrode  2013  is Vd. After charging, the voltage of the pixel electrode  2013  is Vs, in which Vs=Vd. A voltage difference between the pixel electrode  2013  and the storage capacitor  2012  is Vs−Vcom_T 1 . The electric charges between the pixel electrode  2013  and the common electrode  2014  indicate Q=C 1 *(Vs−Vcom_T 1 ). 
     At the time point C 2 , the gate voltage of the TFT is turned off, and the voltage of the common electrode  2014  maintains the first common electrode voltage Vcom_T 1 . Meanwhile, the electric charges between the pixel electrode  2013  and the common electrode  2014  still indicate C 1 *(Vs−Vcom_T 1 ). 
     However, the voltage Vs of the pixel electrode  2013  has a voltage drop ΔV such that the voltage of the pixel electrode  2013  becomes Vs−ΔV. 
     At the time point D 2 , the common electrode line  204  alters the voltage of the common electrode into the second common electrode voltage Vcom_T 2 . In accordance with charge conservation: 
     Q=C 1 *(Vs−ΔV−Vcom_T 1 )=C 1 *(V′s−Vcom_T 2 ), because Vcom_T 2 &gt;Vcom_T 1 , V′s&gt;Vs−ΔV. Due to V′s&gt;V′s−ΔV, and Vs=Vd&gt;Vs−ΔV, the final voltage V′s of the pixel electrode  2013  is closer to the target voltage Vd by which the data line  203  charges the pixel electrode  2013 . 
     Referring to  FIG. 6 ,  FIG. 6  is a schematic drawing illustrating waveform of the LCD panel according to a third preferred embodiment of the present invention. 
     Referring to  FIG. 3  and  FIG. 6 , in the embodiment shown in  FIG. 6 , respective voltages of the data line  203 , the gate of TFT and the common electrode line  204  are controlled according to sequential order of time points A 3 , B 3 , C 3 , D 3 , and E 3 , which are sequentially separated by intervals. 
     The time point A 3  at which the data line  203  provides the pixel voltage to the pixel unit is earlier than the time point B 3  at which the gate voltage Vg of the TFT is turned on. 
     At the time point B 3 , the gate voltage of the TFT is turned on, and the data line  203  begins to charge the pixel electrode  2013 . The target voltage of the data line  203  charging the pixel electrode  2013  is Vd. After charging, the voltage of the pixel electrode  2013  is Vs, in which Vs=Vd. A voltage difference between the pixel electrode  2013  and the common electrode  2014  is Vd−Vcom_T 2 . The electric charges between the pixel electrode  2013  and the common electrode  2014  indicate:
 
 Q=C 1*( Vs−V com —   T 2).
 
     At the time point C 3 , the common electrode line  204  alters the second common electrode voltage Vcom_T 2  to the first common electrode voltage Vcom_T 1 . The data line  203  continuous charging the pixel electrode  2013  at the same time. After charging, the voltage of the pixel electrode  2013  is still Vs=Vd. A voltage difference between the pixel electrode  2013  and the common electrode  2014  is Vd−Vcom_T 1 . The electric charges between the pixel electrode  2013  and the common electrode  2014  indicate:
 
 Q=C 1*( Vs−V com —   T 1).
 
     At the time point D 3 , the gate voltage of the TFT is turned off, and the data line  203  stops charging the pixel electrode  2013 . Under this condition, when the gate voltage Vg of the TFT is turned off, the voltage Vs of the pixel electrode  2013  has a voltage drop ΔV such that the voltage of the pixel electrode  2013  becomes Vs−ΔV. The electric charges in the pixel electrode  2013  comply with C  1 *(Vs−ΔV−Vcom_T 1 ). 
     At the time point E 3 , the common electrode line  204  alters the first common electrode voltage Vcom_T 1  into the second common electrode voltage Vcom_T 2 . In accordance with charge conservation, the electric charges in the pixel electrode  2013  comply with C 1 *(Vs−ΔV−Vcom_T 1 )=C 1 *(V′s−Vcom_T 2 ). 
     Because Vcom_T 2 &gt;Vcom_T 1 , V′s&gt;Vs−ΔV. Due to V′s&gt;Vs−ΔV, and Vs=Vd&gt;Vs−ΔV, the final voltage V′s of the pixel electrode  2013  is closer to the target voltage Vd by which the data line  203  charges the pixel electrode  2013 . 
     In the present invention, the voltages of the positive and negative polarities are more symmetrical. The problem of the crosstalk resulting form the nonsymmetrical positive and negative voltages when the gate voltage of the TFT is turned off and the voltage of the pixel electrode jumps has been effectively solved in the present invention. 
     Referring to  FIG. 7 , a method for controlling the voltage of the LCD panel is provided in the present invention. 
     At step S 701 , a common electrode line  204  is provided, and the common electrode line  204  is coupled to the common electrode. 
     At step S 702 , the data line  203  charges the pixel electrode  2013 . 
     At step S 703 , the common electrode line  204  provides alternating common electrode voltages to the common electrode  2014 , so that a voltage of the pixel electrode  2013  still approaches a target voltage by which the data line charges the pixel electrode  2013  when a gate voltage of the TFT is turned off. 
     The LCD panel herein includes a gate driver, a source driver, a plurality of gate lines and a plurality of data lines. The gate lines and the data lines define a plurality of pixel units  201 , and each pixel unit  201  comprises a TFT, a common electrode  2014 , and a pixel electrode  2013 . 
     Specifically, the common electrode voltages comprise a first common electrode voltage and a second common electrode voltage, and the second common electrode voltage is larger than the first common electrode voltage. The first common electrode voltage and the second common electrode voltage are generated alternately in a fixed period of time, which is a duration of scanning a frame. 
     Referring to  FIG. 4  and  FIG. 7 , respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to sequential order of preset time points A 1 , B 1 , and C 1 , which are sequentially separated by interval. 
     At the time point A 1 , the data line  203  provides the pixel voltage to the pixel unit  201 . 
     At the time point B 1 , the gate voltage of the TFT is turned on, and the data line  203  begins to charge the pixel electrode  2013 . The common electrode line  204  provides the first common electrode voltage to the common electrode  2014 . 
     At the time point C 1 , the gate voltage of the TFT is turned off, the common electrode line  204  provides the second common electrode voltage to the common electrode  2014 . 
     Referring to  FIG. 5  and  FIG. 7 , respective voltages of the data line, a gate of TFT, and the common electrode line are controlled according to sequential order of preset time points A 2 , B 2 , C 2 , and D 2 , which are sequentially separated by interval. 
     At the time point A 2 , the data line  203  provides the pixel voltage to the pixel unit  201 , and the common electrode line  204  alters the second common electrode voltage to the first common electrode voltage. 
     At the time point B 2 , the gate voltage of the TFT is turned on, and the data line  203  begins to charge the pixel electrode  2013 . 
     At the time point C 2 , the gate voltage of the TFT is turned off. 
     At the time point D 2 , the common electrode line  204  is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode  2014 . 
     Referring to  FIG. 6  and  FIG. 7 , the data line, a gate of TFT and the common electrode line control each of responsive voltages according to sequential order of preset time points A 3 , B 3 , C 3 , D 3 , and E 3 . 
     At the time point A 3 , the data line  203  provides the pixel voltage to the pixel unit  201 . 
     At the time point B 3 , the gate voltage of the TFT is turned on, and the data line  203  begins to charge the pixel electrode  2013 . 
     At the time point C 3 , the common electrode line  204  alters the second common electrode voltage to the first common electrode voltage and provide to the common electrode  2014 . 
     At the time point D 3 , the gate voltage of the TFT is turned off. 
     At the time point E 3 , the common electrode line  204  is utilized to alter the first common electrode voltage into the second common electrode voltage and provide to the common electrode  2014 . 
     While the preferred embodiments of the present invention have been illustrated and described in detail, various modifications and alterations can be made by persons skilled in this art. The embodiment of the present invention is therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.