Patent ID: 8421783

Claim:
An active matrix display device comprising: a pixel portion over a substrate, and comprising a first transistor; and a driver circuit over the substrate, and comprising a shift register comprising: a flip-flop comprising a first output terminal, a second output terminal, and a second transistor; a third transistor comprising a third gate, a third source, and a third drain; a fourth transistor comprising a fourth gate, a fourth source, and a fourth drain; a fifth transistor comprising a fifth gate, a fifth source, and a fifth drain; a sixth transistor comprising a sixth gate, a sixth source, and a sixth drain, wherein the third gate and the fifth gate are operationally connected to the first output terminal, wherein the fourth gate and the sixth gate are operationally connected to the second output terminal, wherein one of the third source and the third drain and one of the fourth source and the fourth drain are electrically connected to a first line configured to supply a clock signal, wherein the other of third source and the third drain and the other of the fourth source and the fourth drain are electrically connected to an output terminal of the shift register, wherein one of the fifth source and the fifth drain and one of the sixth source and the sixth drain are electrically connected to a second line configured to supply a clock back signal, and wherein the other of the fifth source and the fifth drain and the other of the sixth source and the sixth drain are electrically connected to each other.