Patent ID: 7928437

Claim:
A thin film transistor substrate comprising: a signal line and a discharge line formed on a substrate; a signal supply pad formed on one end of the signal line to supply a signal to the signal line; and an electrostatic discharge protection circuit including a plurality of protection thin film transistors formed between the signal supply pad and the discharge line and/or between the signal line and the discharge line, the protection thin film transistors being connected in series, wherein each of the protection thin film transistors comprises: a first gate electrode; a gate insulating layer covering the first gate electrode; a first semiconductor layer and a first ohmic contact layer formed on the gate insulating layer, wherein the first semiconductor layer and a first ohmic contact layer overlap the first gate electrode; a first source electrode and a first drain electrode formed facing each other on the first ohmic contact layer; wherein the first source electrode of one of the protection thin film transistors is electrically connected to the first drain electrode of the adjacent protection thin film transistor, and the first source electrode of one of the protection thin film transistors and the first drain electrode of the adjacent protection thin film transistor are floated.