酸化物半導体薄膜トランジスタを用いたアクティブ・マトリックス型FEDの回路検討

抄録

A TFT (Thin film transistor) driving-circuit for active-matrix was discussed to enlarge FEDs (Field emission display) using an MIM (Metal-insulator-metal) -cathode. The cathode has a thin insulator sandwiched with 2 conductive films, and the capacitance is proportional to the display size. In the simple matrix display, it is impossible to charge the wirings connected to the MIM-cathode to specification voltage within scanning time with enlarging of the display. We introduced an active matrix method, where the MIM-cathode was charged with the current switched by an oxide semiconductor TFT connected to DC power supply. The capability of 55-inch FHD (Full high definition) display was evaluated assuming the mobility of the TFT to be 10 cm²/Vs. As a result, it was shown that the current can be supplied to the MIM-cathode sufficiently by using the driving transistor T_d with channel length of 8 µm and width of 100 µm. The wirings for DC power supply and GND are formed in both horizontal and vertical directions. The voltage-drop at the central portion of the display generated by the wiring resistance can be suppress to be less than 0.2 V, and the voltage has little influence on image quality. The performance of the 55-inch FHD display driven by active matrix with oxide semiconductor TFT was confirmed.