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.
Highlights
The Internet of Things and wearable sensor technologies have accelerated the development of various sensors and their integrated design methodologies
This paper presents a new simultaneous TX driving and multiplexing technique for capacitive touch sensors that employs multi-level Hadamard (M-H) matrices for communication systems [6,7]
A theoretical model for capacitive touch sensors can be derived from a multiple input multiple output (MIMO) system that is stimulated by orthogonal active signals [8]
Summary
The Internet of Things and wearable sensor technologies have accelerated the development of various sensors and their integrated design methodologies. This paper presents a new simultaneous TX driving and multiplexing technique for capacitive touch sensors that employs multi-level Hadamard (M-H) matrices for communication systems [6,7]. Will be employed to extract SNRs for M-H matrices that are applicable to capacitive touch sensors This attempt provides unified and quantitative views for modeling and evaluating multiplexing techniques for different sensor systems. Odd number orders of multiple TX lines and the corresponding code sequences can be applied, which yields a better H matrix to satisfy the given system requirement for the scan rate or the reporting rate of the sensor to maximize the SNR Another important feature of these H matrices is that regular column sum of the M-H matrix and the acquired capacitive signals can be configured due to their capacity efficiency.
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