Patent ID: 7365713

Claim:
A semiconductor device comprising a pixel provided with a light emitting element, wherein: the pixel comprises: a current supply line; first to third transistors each having a gate electrode and first and second electrodes; and capacitor means having first and second electrodes; the first electrode of the capacitor means is electrically connected with the gate electrode of the first transistor and the first electrode of the second transistor; the second electrode of the second transistor is electrically connected with the first electrode of the first transistor and the first electrode of the third transistor; during a first period, the second and third transistors are turned on so that a charge is stored in the capacitor means through the first and second transistors; during a second period, the third transistors is turned off and the second transistor is turned on so that a voltage held by the capacitor means is made equal to a threshold voltage of the first transistor; during a third period, the second and third transistors are turned off so that a video signal is inputted through the second electrode of the capacitor means; and during a fourth period, the second transistors is turned off and the third transistor is turned on so that a current flows between a source and a drain of each of the first and third transistors.