Patent ID: 8120557
Filing Date: 2012-02-21
Classification: C09K,G09G,H01L,H05B,Y02E,Y02P

Abstract:
1. A method for driving a light emitting device comprising: selecting a scanning line to turn on a third transistor and a fourth transistor whose gate electrodes are connected with the scanning line; flowing a constant current through a signal line connected with one of a source and a drain of the third transistor and connected with one of a source and a drain of the fourth transistor; determining a gate voltage of a first transistor by a value Ic of the constant current wherein a drain of the first transistor is connected with the other of the source and the drain of the third transistor, and a gate of the first transistor is connected with the other of the source and the drain of the fourth transistor; determining a gate voltage of a second transistor from the gate voltage of the first transistor wherein a gate of the second transistor is connected with the gate of the first transistor, and a source of the second transistor is connected with a source of the first transistor; keeping a drain current of the second transistor same as a drain current of the first transistor; flowing the drain current of the second transistor through a light emitting layer in a writing period; turning off the third transistor and the fourth transistor; keeping the drain of the first transistor floating; keeping the gate voltage of the second transistor from the writing period to a display period; and keeping the drain current of the second transistor from the writing period to the display period.