Patent ID: 7586478

Claim:
An active matrix liquid crystal display device comprising: a plurality of pixels arranged in a matrix, wherein one of the plurality of pixels includes a fifth thin film transistor; and a driver circuit electrically connected to a gate of the fifth thin film transistor, wherein the driver circuit comprises: a first thin film transistor having a first impurity region electrically connected to a first terminal; a second thin film transistor having a first impurity region electrically connected to a second terminal; a third thin film transistor having a first impurity region electrically connected to a third terminal; a fourth thin film transistor having a first impurity region electrically connected to a fourth terminal; and a first power supply line supplied with a first constant potential, wherein: the first to fourth thin film transistors have a same conductivity type, a second impurity region of the first thin film transistor and a second impurity region of the second thin film transistor are electrically connected to a fifth terminal, a second impurity region of the third thin film transistor and a second impurity region of the fourth thin film transistor are electrically connected to a gate electrode of the first thin film transistor, a gate electrode of the second thin film transistor and a gate electrode of the fourth thin film transistor are electrically connected to a sixth terminal, a gate electrode of the third thin film transistor is electrically connected to the first impurity region of the third thin film transistor, and the first terminal is electrically connected to the first power supply line.