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Sensors 2017, 17(9), 2016; https://doi.org/10.3390/s17092016

Analysis of Multi-Level Simultaneous Driving Technique for Capacitive Touch Sensors

1
College of Information and Communication Engineering, Sungkyunkwan University, Seobu-ro 2066, 16419 Suwon, Korea
2
System LSI Division, Samsung Electronics, 18448 Hwasung, Korea
*
Author to whom correspondence should be addressed.
Received: 31 July 2017 / Revised: 30 August 2017 / Accepted: 1 September 2017 / Published: 2 September 2017
(This article belongs to the Special Issue Tactile Sensors and Sensing)
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Abstract

The signal-to-noise ratio (SNR) and driving levels of capacitive touch sensors determine the applicability of these sensors to thinner displays and sensor-integrated modules. The simultaneous driving technique has been widely applied to capacitive touch sensors to cope with various types of environmental noise. A Hadamard matrix has been used to determine the driving code and multiplex capacitive signals required to increase the SNR and responsivity of touch sensors. Using multi-level Hadamard matrices, a new driving technique for sensing concurrent capacitive elements across multiple rows of a touch panel was developed. The technique provides more effective design choices than the existing bipolar driving method by supporting a variety of orders of matrices and regular capacity. The required TX voltage can be reduced by applying the Kronecker product for higher orders of simultaneous driving. A system model is presented for multiplexing capacitive signals to extract the SNR of the existing Hadamard matrices as well as one of the proposed multi-level sequences. In addition, the corresponding multi-level drivers and receivers were implemented to verify the theoretical expectations and simulation results of the proposed technique. View Full-Text
Keywords: capacitive touch sensor; multi-level Hadamard matrix; simultaneous driving; multi-level driving; code-division multiplexing capacitive touch sensor; multi-level Hadamard matrix; simultaneous driving; multi-level driving; code-division multiplexing
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Park, J.K.; Lee, C.-J.; Kim, J.T. Analysis of Multi-Level Simultaneous Driving Technique for Capacitive Touch Sensors. Sensors 2017, 17, 2016.

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