In-plane switching display device having common electrode overlapping channel forming region, and double gate TFT

An In-Plane Switching display device comprising:

• a semiconductor film formed over a substrate, said semiconductor film having at least a channel forming region, a source region, and a drain region;
• a gate electrode adjacent to the semiconductor film with a gate insulating film interposed therebetween;
• source and drain electrodes connected to the source and drain regions, respectively;
• an insulating layer formed over the source and drain electrodes;
• a common electrode formed on the insulating layer;
• a pixel electrode formed on the insulating layer and electrically connected to the drain electrode via a contact hole in the insulating layer;
• and
• a capacitor electrically connected to the pixel electrode;
• wherein the thin film transistor is double gate structure thin film transistor,
• wherein an electric field parallel to the face of the substrates is applied between the pixel electrode and the common electrode, and
• wherein the common electrode overlaps the semiconductor film.

An In-Plane Switching display device comprising:

• a pair of substrates,
• at least one thin film transistor formed over one of the pair of substrates;
• an insulating layer formed over the thin film transistor;
• a common electrode formed on the insulating layer;
• a pixel electrode formed on the insulating layer and electrically connected to the thin film transistor via a contact hole in the insulating layer;
• and
• a capacitor electrically connected to the pixel electrode;
• wherein the thin film transistor comprises a semiconductor island, a gate insulating layer on the semiconductor island, and first and second gate electrodes on the gate insulating layers
• wherein the pair of the substrates is surrounded by a sealing material, and spacers are formed in the region in which the sealing material is formed, and
• wherein the common electrode overlaps the semiconductor island.