Patent ID: 8441049

Claim:
A flat panel display device, comprising: a pixel portion including a plurality of thin film transistors, wherein the plurality of thin film transistors are driven by signals applied through a gate line and a data line; and a driving circuit portion having at least one thin film transistor to apply the signals to the pixel portion and connected to the gate line and the data line, wherein an average number of polysilicon grains per unit area formed in an active channel of the at least one thin film transistor is less than an average number of polysilicon grains formed in an active channel of one of the plurality of thin film transistors included in the pixel portion, wherein polysilicon grains are defined by primary grain boundaries, wherein a current mobility in the driving circuit portion is larger than a current mobility in the pixel portion, and wherein the polysilicon grains formed in the active channel region of the pixel portion are more uniform than the polysilicon grains formed in the active channel region of the driving circuit portion.