A 0.4 V driving multi-touch capacitive sensor with the driving signal frequency set to (n+0.5) times the inverse of the LCD VCOM noise period

Author

Jae-Seung Lee ; Dong-Hee Yeo ; Sang-Soo Lee ; Hye-Jung Kwon ; Jae-Yoon Sim ; Byung-Sub Kim ; Hong June Park

Author_Institution

Pohang Univ. of Sci. & Technol. (POSTECH), Pohang, South Korea

fYear

2014

fDate

1-5 June 2014

Firstpage

682

Lastpage

685

Abstract

The time-periodic property of the LCD VCOM noise is utilized to reduce the effect of the VCOM noise on the mutual-capacitance measuring touch sensor placed on a LCD panel. The amplitude of the touch sensor driving signal (VSTM) can be reduced reliably down to 0.4 V with the reporting rate of 189 Hz, by using the following two methods. (1) The frequency of VSTM is set to (n+0.5)·f_N, by synchronizing VSTM to a LCD gate driver signal with a referenceless CDR. fN is the inverse of the LCD VCOM noise period (TN) and n is a positive integer. (2) The reset period of the RX integrator is set to 2·TN.

Keywords

capacitance measurement; capacitive sensors; driver circuits; liquid crystal displays; tactile sensors; CDR; LCD VCOM noise period; LCD gate driver signal; VSTM; driving signal frequency; frequency 189 Hz; multitouch capacitive sensor; mutual-capacitance measuring touch sensor; time-periodic property; touch sensor driving signal amplitude; voltage 0.4 V; Electrodes; Logic gates; Noise; Noise measurement; Semiconductor device measurement; Tactile sensors; Voltage measurement; VCOM noise; mutual-capacitance; touch sensor;

fLanguage

English

Publisher

ieee

Conference_Titel

Circuits and Systems (ISCAS), 2014 IEEE International Symposium on

Conference_Location

Melbourne VIC

Print_ISBN

978-1-4799-3431-7

Type

conf

DOI

10.1109/ISCAS.2014.6865227

Filename

6865227