Patent ID: 8026877

Claim:
A light-emitting device comprising: a pixel comprising: a light-emitting element, a first transistor for determining a value of a current flowing to the light-emitting element, a second transistor for determining a light emission or non light emission of the light-emitting element depending on a video signal input through a signal line, a third transistor for controlling an input of the video signal, and a fourth transistor for forcing the light-emitting element into a non-emission state irrelevant from the video signal, wherein the light-emitting element, the first transistor, and the second transistor are connected in series between a first power line and a counter electrode of the light-emitting element, wherein a source of the first transistor is connected to the first power line and a gate electrode of the first transistor is connected to a second power line so that a voltage between the gate electrode and the source of the first transistor is constantly fixed, wherein the first transistor has a channel length longer than a channel width, and the second transistor has a channel length equal to or shorter than a channel width, and wherein a ratio of the channel length to the channel width of the first transistor is 5 or more.