Patent ID: 8772773

Claim:
A display device comprising: a scan line and a signal line intersecting with each other over a substrate having an insulating surface; a pixel portion including a pixel electrode and a transistor, wherein the transistor comprises: a gate electrode electrically connected to the scan line; a channel formation region including a fourth oxide semiconductor layer; a first wiring layer electrically connected to the signal line and the fourth oxide semiconductor layer; and a second wiring layer electrically connected to the pixel electrode and the fourth oxide semiconductor layer; a non-linear element between the pixel portion and a signal input terminal disposed at a periphery of the substrate, wherein the non-linear element comprises: a gate electrode electrically connected to the scan line or the signal line; a gate insulating layer covering the gate electrode; a second oxide semiconductor layer over the gate insulating layer; a third oxide semiconductor layer over the gate insulating layer; a first conductive layer over the gate insulating layer with the second oxide semiconductor layer positioned therebetween; a second conductive layer over the gate insulating layer with the third oxide semiconductor layer positioned therebetween; and a first oxide semiconductor layer in contact with a top surface and a side surface of each of the first conductive layer and the second conductive layer, wherein the second conductive layer of the non-linear element is electrically connected to the gate electrode via a third wiring layer, and wherein a part of the second conductive layer is surrounded by the first conductive layer when seen from above.