Patent ID: 7719498

Claim:
A light emitting device comprising: a signal line; a power source line; an OLED; a first transistor; a second transistor; and a third transistor for controlling connection between a gate electrode and a drain area of the first transistor, wherein the gate electrode of the first transistor and a gate electrode of the second transistor are connected with each other, wherein source areas of the first transistor and the second transistor are both connected with the power source line, wherein a drain area of the second transistor is connected with a pixel electrode of the OLED, wherein a current which flows on the signal line flows between the drain area and the source area of the first transistor when the gate electrode and the drain area of the first transistor are connected with each other, and wherein the drain area of the first transistor is floating when the gate electrode and the drain area of the first transistor are disconnected from each other.