Pixel driving device for a liquid crystal display

Abstract

A pixel driving device for a liquid crystal display. The pixel driving device includes a thin film transistor (TFT), a pixel capacitor, a storage capacitor, a first common line, and a second common line. The TFT includes a gate electrode coupled to a scan line and a source coupled to the data line. The pixel capacitor is coupled to the TFT drain electrode and the first common line, while the storage capacitor is coupled to the TFT drain electrode and the second common line. The first common line and the second common line possess different common voltages. When a pixel voltage is applied to the pixel, the pixel capacitor and the storage capacitor possess different capacitor voltage values by being coupled to different common lines, respectively.

What is claimed is:  
     
         1 . A driving device for a pixel of a liquid crystal display, the driving device comprising: 
 a scan line;    a data line;    a thin film transistor (TFT) including a gate electrode coupled to the scan line, a source electrode coupled to the data line, and a drain electrode;    a pixel capacitor coupled to the drain electrode; and    a storage capacitor coupled to the drain electrode and the pixel capacitor; wherein the pixel capacitor and the storage capacitor have different capacitor voltage values when a pixel voltage is applied to the pixel.    
     
     
         2 . The driving device according to  claim 1 , wherein the liquid crystal display is a normally white (NW) mode liquid crystal panel.  
     
     
         3 . The driving device according to  claim 1 , wherein the liquid crystal display is a twisted nematic (TN) mode liquid crystal panel.  
     
     
         4 . The driving device according to  claim 1 , wherein when an upper electrode of the storage capacitor and a lower electrode of the storage capacitor are short-circuited, a capacitor voltage of the pixel capacitor is maintained by disconnecting the pixel capacitor from the data line.  
     
     
         5 . The driving device according to  claim 4 , wherein a difference between the capacitor voltages of the pixel capacitor and the storage capacitor enables the pixel to display its minimum brightness.  
     
     
         6 . A pixel driving device for a pixel in a liquid crystal display, the pixel being coupled to a scan line and a data line, and the pixel driving device comprising: 
 a thin film transistor (TFT) including a gate electrode coupled to the scan line, a source electrode coupled to the data line, and a drain electrode;    a pixel capacitor coupled to the drain electrode;    a storage capacitor coupled to the drain electrode;    a first common line having a first common voltage level, wherein the pixel capacitor is coupled between the drain electrode and the first common line; and    a second common line having a second common voltage level, wherein the storage capacitor is coupled between the drain electrode and the second common line, and when a pixel voltage is applied to the pixel, the pixel capacitor and the storage capacitor have different capacitor voltage values by being coupled to the first and second common lines respectively.    
     
     
         7 . The pixel driving device according to  claim 6 , wherein the liquid crystal display is a normally white (NW) mode liquid crystal panel.  
     
     
         8 . The pixel driving device according to  claim 6 , wherein the liquid crystal display is a twisted nematic (TN) mode liquid crystal panel.  
     
     
         9 . The pixel driving device according to  claim 6 , wherein when an upper electrode of the storage capacitor and a lower electrode of the storage capacitor are short-circuited, a capacitor voltage of the pixel capacitor is maintained by disconnecting the pixel capacitor from the data line.  
     
     
         10 . The pixel driving device according to  claim 9 , wherein a difference between the first common voltage and the second common voltage level enables the pixel to display its minimum brightness.  
     
     
         11 . A pixel driving device for a liquid crystal display, the pixel driving device comprising: 
 a scan line;    a data line;    a thin film transistor (TFT) including a gate electrode coupled to the scan line, a source electrode coupled to the data line, and a drain electrode;    a first power source;    a second power source;    a pixel capacitor coupled between the drain electrode and the first power source; and    a storage capacitor coupled between the drain electrode and the second power source.    
     
     
         12 . The pixel driving device according to  claim 11 , wherein the first power source provides a first voltage level and the second power source provides a second voltage level, wherein the second voltage level is different from the first voltage level.  
     
     
         13 . The pixel driving device according to  claim 12 , wherein when an upper electrode of the storage capacitor and a lower electrode of the storage capacitor are short-circuited, a capacitor voltage of the pixel capacitor is maintained by disconnecting the pixel capacitor from the data line.  
     
     
         14 . The pixel driving device according to  claim 13 , wherein a difference between the first voltage level and the second voltage level enables a pixel associated with the thin film transistor to display its minimum brightness.