Driving method of light emitting device

Abstract

If a potential of a gate electrode of a driving transistor varies after a gray scale signal is inputted into each pixel, a current value of a current supplied to a light emitting element varies so that accurate gray scale display cannot be obtained. In particular, in the case of performing black display, current may flow, which makes clear black display difficult. Accordingly, the invention provides a light emitting device capable of performing accurate gray scale display, and a driving method thereof. According to the invention, a signal for display is inputted plural times within a predetermined timing period, or a writing operation period is lengthened. Consequently, the gate voltage of the transistor is determined after the anode potential of the light emitting element is stabilized, and therefore accurate gray scale display can be performed.

1 . A driving method of a light emitting device comprising a step of providing n subframe periods (n is a positive integer) in a frame period, 
 wherein each of the subframe periods comprises a writing operation period; and    wherein at least one of the subframe periods has a plurality of periods for inputting an erasing signal.    
   
   
       2 . A driving method of a light emitting device comprising a step of providing n subframe periods (n is a positive integer) in a frame period, 
 wherein each of the subframe periods comprises a writing operation period; and    wherein at least one of the subframe period has a plurality of writing operation periods.    
   
   
       3 . A driving method of a light emitting device comprising a step of inputting a video signal and a erasing signal to perform a digital gray scale display, 
 wherein a period for inputting the erasing signal is longer than a period for inputting the video signal.    
   
   
       4 . A driving method of a light emitting device comprising a step of inputting a video signal and a erasing signal to perform a digital gray scale display, 
 the light emitting device comprising: 
 a switching transistor, wherein a source electrode or a drain electrode thereof is connected to a signal line and a gate electrode thereof is connected to a scan line;  
 a driving transistor, wherein a gate electrode thereof is connected to the switching transistor; and  
 a light emitting element connected to a source electrode or a drain electrode of the driving transistor,  
   wherein a period for inputting the erasing signal is longer than a period for inputting the video signal.    
   
   
       5 . A driving method of a light emitting device comprising a step of inputting the video signal and a erasing signal to perform a digital gray scale display, 
 the light emitting device comprising: 
 a switching transistor, wherein a source electrode or a drain electrode thereof is connected to a signal line and a gate electrode thereof is connected to a scan line;  
 a driving transistor, wherein a gate electrode thereof is connected to the switching transistor;  
 a erasing transistor for discharging a charge corresponding to a gate-source voltage of the driving transistor; and  
 a light emitting element connected to a source electrode or a drain electrode of the driving transistor,  
   wherein a period for inputting the erasing signal is longer than a period for inputting the video signal.    
   
   
       6 . A driving method of a light emitting device comprising a step of inputting the video signal and a erasing signal to perform a digital gray scale display, 
 the light emitting device comprising: 
 a switching transistor, wherein a source electrode or a drain electrode thereof is connected to a signal line and a gate electrode thereof is connected to a scan line;  
 a driving transistor, wherein a gate electrode thereof is connected to the switching transistor;  
 a erasing transistor for discharging a charge corresponding to a gate-source voltage of the driving transistor;  
 a transistor connected to the driving transistor in series and having an fixed gate potential; and  
 a light emitting element connected to a source electrode or a drain electrode of the driving transistor,  
   wherein a period for inputting the erasing signal is longer than a period for inputting the video signal.    
   
   
       7 . A driving method of a light emitting device comprising a step of inputting a gray scale signal to perform an analog gray scale display, 
 wherein the gray scale signal is inputted plural times.    
   
   
       8 . A driving method of a light emitting device comprising a step of inputting a gray scale signal to perform an analog gray scale display, 
 wherein a period for inputting the gray scale signal in the case of low-gray scale display is longer than that in case of high-gray scale display.