Display device and driving method of display device

Abstract

It is an object of the present invention to reduce a cause of pseudo contour when display is performed with a time gray scale method. According to the present invention, one pixel is divided into m sub-pixels so that an area ratio of each sub-pixel becomes 2 0 :2 1 :2 2 : . . . :2 m−3 :2 m−2 :2 m−1 (m is an integer number of m≧2), and one frame is divided into n sub-frames so that a ratio of a lighting period in each sub-frame becomes 2 0 :2 m :2 2m : . . . :2 (n−3)m :2 (n−2)m :2 (n−1)m (n is an integer number of n≧2). Then, a gray scale is expressed by controlling a manner of lighting in each of the m sub-pixels in each of the n sub-frames.

1 . A method for driving a display device, where a pixel including m (m is an integer number of m≧2) of sub-pixels provided with a light-emitting element, comprising the steps of: 
 having an area ratio of the m sub-pixels 2 0 :2 1 :2 2 : . . . :2 m−3 :2 m−2 :2 m−1 ;    dividing one frame into n (n is an integer number of n≧2) of sub-frames in each of the m sub-pixels; and    having a ratio in a length of a lighting period of the n sub-frames 2 0 :2 m :2 2m : . . . :2 (n−3)m :2 (n−2)m :2 (n−1)m ,    wherein a gray scale of the pixel is expressed by controlling the sum of a lighting period of the sub-frame when the m sub-pixels are in a lighting state, in each of the n sub-frames.    
   
   
       2 . A method for driving a display device according to  claim 1 , wherein at least one sub-frame of the n sub-frames is divided into two sub-frames having a lighting period that is half the length of the sub-frame.  
   
   
       3 . A method for driving a display device according to  claim 1 , wherein the sub-frame dividing the lighting period is a sub-frame having a longest lighting period of the n sub-frames.  
   
   
       4 . A method for driving a display device according to  claim 1 , the n sub-frames are arranged in an ascending order.  
   
   
       5 . A method for driving a display device according to  claim 1 , the n sub-frames are arranged in a descending order.  
   
   
       6 . A method for driving a display device according to  claim 1 , wherein a relation between luminance of the pixel and the gray scale is linearly when the gray scale is low, and a relation between luminance of the pixel and the gray scale is nonlinearly when the gray scale is high.  
   
   
       7 . A display device comprising: 
 a pixel including m (m is an integer number of m≧2) of sub-pixels provided with a light-emitting element,    each of the sub-pixels comprising:    a select transistor,    a driving transistor, and    a holding capacitor    a signal line electrically connected to a first electrode of the select transistor,    a scanning line,    a first power supply line electrically connected to a first electrode of the driving transistor, and    a second power supply line,    wherein a second electrode of the select transistor is electrically connected to a gate electrode of the driving transistor, and    wherein, in the light-emitting element, a first electrode is electrically connected to a second electrode of the driving transistor and a second electrode is electrically connected to the second power supply line.    
   
   
       8 . A display device according to  claim 7 , wherein the scanning line is shared among the m sub-pixels.  
   
   
       9 . A display device according to  claim 7 , wherein the scanning line is shared among the m sub-pixels.  
   
   
       10 . A display device according to  claim 7 , wherein the first power supply line is shared among the m sub-pixels.  
   
   
       11 . A display device comprising: 
 a pixel including m (m is an integer number of m≧2) of sub-pixels provided with a light-emitting element,    each of the sub-pixels comprising:    a select transistor,    a driving transistor, and    a holding capacitor    a scanning line,    a first power supply line electrically connected to a first electrode of the driving transistor, and    a second power supply line,    said display device further comprising 2 or more and m or less signal lines electrically connected to the pixel,    wherein a second electrode of the select transistor is electrically connected to a gate electrode of the driving transistor, and    wherein, in the light-emitting element, a first electrode is electrically connected to a second electrode of the driving transistor and a second electrode is electrically connected to the second power supply line.    
   
   
       12 . A display device comprising: 
 a pixel including m (m is an integer number of m≧2) of sub-pixels provided with a light-emitting element,    each of the sub-pixels comprising:    a select transistor,    a driving transistor, and    a holding capacitor    a signal line electrically connected to a first electrode of the select transistor,    a first power supply line electrically connected to a first electrode of the driving transistor, and    a second power supply line,    said display device further comprising 2 or more and m or less scanning lines electrically connected to the pixel,    wherein a second electrode of the select transistor is electrically connected to a gate electrode of the driving transistor, and    wherein, in the light-emitting element, a first electrode is electrically connected to a second electrode of the driving transistor and a second electrode is electrically connected to the second power supply line.    
   
   
       13 . A display device comprising: 
 a pixel including m (m is an integer number of m≧2) of sub-pixels provided with a light-emitting element,    each of the sub-pixels comprising:    a select transistor,    a driving transistor, and    a holding capacitor    a signal line electrically connected to a first electrode of the select transistor,    a scanning line, and    said display device further comprising 2 or more and m or less power supply lines electrically connected to the pixel,    wherein the power supply line electrically connected to a first electrode of the driving transistor,    wherein a second electrode of the select transistor is electrically connected to a gate electrode of the driving transistor, and    wherein, in the light-emitting element, a first electrode is electrically connected to a second electrode of the driving transistor and a second electrode is electrically connected to the second power supply line.    
   
   
       14 . An electronic device equipped with the display device according to  claim 7.