P‐197: Active Matrix Touch Sensor Detecting Time‐Constant Change Implemented by IGZO TFTs

Abstract

We propose a novel concept of using the RC time-constant to sense the capacitance change induced by touch and demonstrate it with a sensing circuit implemented by IGZO TFTs. The pixel circuit is consisted of one resistor and two TFTs in series, which are sequentially turned by consecutive gate pulses. By increasing the delay time of the first gate pulse waveform, a large transient ON current can flow through the TFTs while the second pulse comes, and thus become a significant sensing signal. This pixel consumes low power because the transient current only occurs when a pixel is touched.