Peripheral circuit integrated poly-Si TFT LCD with gray scale representation

A 3.3-in.-diagonal fully integrated low-temperature (<600 degrees C) processed polycrystalline silicon (poly-Si) thin-film transistor (TFT) liquid-crystal display (LCD) with four gray scale (64 colors) representation fabricated on glass is discussed. A contrast ratio in excess of 25 was obtained. The integrated data drive circuits consisted of divided matrix switches, line memories, and multilevel selectors. High-frequency driving capability was achieved by using divided matrix switches with small line memory capacitances. Four gray scale voltages were generated by the multilevel selectors. Integrated scan drive circuits consisted of shift registers, level shifters, ratioless buffers, and multiplexers. High-speed operation and low power consumption were realized by using ratioless buffers. The use of integrating peripheral drive circuits in the prototype display with (132*3)*133 pixels reduced the number of external connections from 531 to 101. The maximum scan and data frequencies were 100 kHz and 10 MHz, respectively. These integrated peripheral circuits should be capable of driving a large display with (640*3)*400 dots at a frame frequency of 60 Hz.<
>