Patent ID: 8599177

Claim:
A method for driving a liquid crystal display device comprising: in a period during which a moving image is displayed, turning on a pixel transistor of a pixel including an oxide semiconductor layer which is electrically connected to a driver circuit portion formed over a first substrate, so that an image signal is supplied to a pixel electrode; and turning on a switching transistor including an oxide semiconductor layer which is electrically connected to a terminal portion formed over the first substrate, so that a common potential is supplied to a common electrode which is electrically connected to the terminal portion through the switching transistor and which is formed over a second substrate; in a period during which a still image is displayed, turning off the pixel transistor so that the pixel electrode is in an electrically floating state; and turning off the switching transistor so that the common electrode is in an electrically floating state; and in a period during which a still image is switched to a moving image, a first step of supplying the common potential to the common electrode; a second step of supplying a power supply voltage to the driver circuit portion; a third step of supplying a clock signal to the driver circuit portion; and a fourth step of supplying a start pulse signal to the driver circuit portion.