Patent ID: 8519929

Claim:
A semiconductor device comprising: a driver circuit comprising a plurality of pulse output circuits each comprising first to third transistors and first to fourth terminals respectively connected to first to fourth signal lines, and a pixel portion, wherein a first terminal of the first transistor is electrically connected to the first signal line, wherein a second terminal of the first transistor is electrically connected to the fourth signal line, wherein a gate and a first terminal of the second transistor are electrically connected to the third signal line, wherein a first terminal of the third transistor is electrically connected to the third signal line, wherein a gate of the third transistor is electrically connected to the second signal line, wherein a gate of the first transistor, a second terminal of the second transistor, and a second terminal of the third transistor are electrically connected to each other, wherein a first clock signal is supplied to the first signal line, wherein a second clock signal is supplied to the second signal line, wherein a preceding stage signal is supplied to the third signal line, wherein an output signal is output from the fourth signal line, and wherein duty ratios of the first clock signal and the second clock signal are different from each other.