When semi-amorphous TFTs are used for forming a signal line driver circuit and a pixel, a large amplitude is required for driving the pixel, and a large power supply voltage is thus needed. On the other hand, when a shift register is made up of transistors having a single conductivity, a bootstrap circuit...http://www.google.de/patents/US7511709?utm_source=gb-gplus-sharePatent US7511709 - Display device
