Patent ID: 7297980

Claim:
A flat panel display device with polycrystalline silicon thin film transistors, comprising: a pixel portion divided by gate lines and data lines and comprising thin film transistors driven by signals applied by the gate lines and data lines; and a driving circuit portion comprising thin film transistors connected to the gate lines and data lines respectively to apply signals to the pixel portion, wherein an average number of grain boundaries of polycrystalline silicon formed in an active channel region of each thin film transistor installed at the driving circuit portion and meet a current direction line is at least one or more less than an average number of grain boundaries of polycrystalline silicon formed in an active channel region of each thin film transistor installed at the pixel portion and meet a current direction line for a unit area of active channels, wherein the polycrystalline silicon grain boundaries formed in the active channel region of each thin film transistor installed at the driving circuit portion include primary polycrystalline silicon grain boundaries that are inclined to the current direction line at an angle of about −45 to 45°, wherein the polycrystalline silicon grain boundaries formed in the active channel region of each thin film transistor installed at the pixel portion include primary polycrystalline silicon grain boundaries that are inclined to the current direction line at an angle of about −45 to 45°, and wherein the active channel of each thin film transistor installed at the pixel portion is longer than the active channel of each thin film transistor installed at the driving circuit portion.