A single layer 3-D touch sensing system for mobile devices application

Li Du*, Chun Chen Liu, Yan Zhang, Yilei Li, Yuan Du, Yen-Cheng Kuan, Mau-Chung Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Touch sensing has been widely implemented as a main methodology to bridge human and machine interactions. The traditional touch sensing range is 2-D and therefore limits the user experience. To overcome these limitations, we propose a novel 3-D contactless touch sensing called Airtouch system, which improves user experience by remotely detecting single/multi-finger position. A single layer touch panel with triangle-shaped electrodes is proposed to achieve multitouch detection capability as well as manufacturing cost reduction. Moreover, an oscillator-based-capacitive touch sensing circuit is implemented as the sensing hardware with the bootstrapping technique to eliminate the interchannel coupling effects. To further improve the system accuracy, a grouping algorithm is proposed to group the useful channels’ data and filter out hardware noise impact. Finally, improved algorithms are proposed to eliminate the fringing capacitance effect and achieve accurate finger position estimation. EM simulation proved that the proposed algorithm reduced the maximum systematic error by 11 dB in the horizontal position detection. The proposed system consumes 2.3 mW and is fully compatible with existing mobile device environments. A prototype is built to demonstrate that the system can successfully detect finger movement in a vertical direction up to 6 cm and achieve a horizontal resolution up to 0.6 cm at 1 cm finger-height. As a new interface for human and machine interactions, this system offers great potential in finger movement detection and gesture recognition for small-sized electronics and advanced human interactive games for mobile device.

Original languageEnglish
Pages (from-to)286-296
Number of pages11
JournalIEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Volume37
Issue number2
DOIs
StatePublished - 1 Feb 2018

Keywords

  • 3-D
  • Bootstrapping
  • Correlated double sampling (CDS)
  • Finger position
  • Gesture recognition
  • Human machine interaction
  • Interchannel coupling
  • Mobile device
  • Touchscreen

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