Patent ID: 8605184

Claim:
A pixel circuit comprising: a photoelectric conversion element; an amplifier circuit; and a transfer transistor for transferring electric charge generated by the photoelectric conversion element to an input node of the amplifier circuit, wherein the transfer transistor has first, second, and third field effect transistors integrated and connected in series from the photoelectric conversion element to a side of the amplifier circuit, the first and second field effect transistors have gate electrodes to be simultaneously collectively driven, and a threshold voltage of the first field effect transistor is set to be higher than that of the second field effect transistor, as the gate electrodes are driven step by step, the electric charge generated by the photoelectric conversion element and transferred via the first field effect transistor is accumulated in a channel region of the second field effect transistor, the electric charge accumulated in the channel region is transferred to an input of the amplifier circuit via the third field effect transistor, the amplifier circuit drives a signal line, so that the accumulated electric charge is read, and a gate electrode of the third field effect transistor has a fixed potential.