Patent ID: 8624875

Claim:
A method for driving a touch panel including at least a first pixel and a second pixel, each including a photo sensor having a photodiode, a first transistor, and a second transistor, comprising: setting a potential of a first photodiode reset signal line which is electrically connected to the photodiode in the first pixel so that a forward bias is applied to the photodiode in the first pixel; and changing a potential of a gate of the second transistor in the second pixel so that a photo sensor output signal line and a photo sensor reference signal line are brought into conduction through the first transistor in the second pixel and the second transistor in the second pixel, thereby a potential of the photo sensor output signal line is changed in accordance with a photocurrent of the photodiode in the second pixel which is electrically connected to a gate of the first transistor in the second pixel, wherein a period for the step of setting and a period for the step of changing are not overlapped with each other, wherein one of a source and a drain of the first transistor in the second pixel is electrically connected to one of the photo sensor output signal line and the photo sensor reference signal line, wherein one of a source and a drain of the second transistor in the second pixel is electrically connected to the other of the photo sensor output signal line and the photo sensor reference signal line, and wherein the other of the source and the drain of the first transistor in the second pixel is electrically connected to the other of the source and the drain of the second transistor in the second pixel.