Capacitance Sensor of Frequency Modulation for Integrated Touchpanels Using Amorphous In-Sn-Zn-O Thin-Film Transistors

Yuki KOGA  Tokiyoshi MATSUDA  Mutsumi KIMURA  Dapeng WANG  Mamoru FURUTA  Masashi KASAMI  Shigekazu TOMAI  Koki YANO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E98-C   No.11   pp.1028-1031
Publication Date: 2015/11/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E98.C.1028
Type of Manuscript: BRIEF PAPER
Category: 
Keyword: 
capacitance sensor,  frequency modulation,  integrated touchpanel,  amorphous In-Sn-Zn-O (α-ITZO),  thin-film transistor (TFT),  

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Summary: 
We have developed a capacitance sensor of frequency modulation for integrated touchpanels using amorphous In-Sn-Zn-O (α-ITZO) thin-film transistors (TFTs). This capacitance sensor consists of a ring oscillator, whose one stage is replaced by a reset transistor, sensing transistor, and sensing electrode. The sensing electrode is prepared as one terminal to form a sensing capacitor when the other terminal is added by a finger. The ring oscillator consists of pseudo CMOS inverters. We confirm that the oscillation frequency changes when the other terminal is added. This result suggests that this capacitance sensor can be applied to integrated touchpanels on flatpanel displays.