A Simulation and Evaluation Method to Estimate the Capacitive Effect on Electrode of Touch Sensors

Abstract

Touch sensors are ubiquitous in daily life. As a type of touch sensor, touch buttons now face the diverse design requirements for electrode patterns. There is no method for evaluating the rationality of electrode shape during the electrode design phase. At this stage, developers typically design electrode shapes based on experience. And in the subsequent stages, multiple electrodes of different shapes will be made for testing and evaluation, and the electrode with the best effect will be selected. Due to the diversity and uncertainty of electrode shape design, this process will consume a lot of time, manpower, and material resources. There are numerous studies on simulation method of touch panels and touch screens, but due to differences in electrode structures, it is difficult to apply their results to evaluate surface sensing touch buttons. Therefore, it is meaningful to study the influence of electrode shape on sensing ability of touch buttons and find a simulation and evaluation method to guide electrode design. This research proposes a new statistical calculation method for touch mutual capacitance based on the finite element method (FEM). Subsequently, calculate the new mutual capacitance matrix within the recognition region based on the boundary conditions. Next, evaluation indicators and calculation methods are proposed based on the difference between the ideal recognition area and the simulation results. Finally, a series of experiments are designed and an experimental platform is developed to verify the simulation results.

Keywords

• Capacitive sensors
• electrode shape
• touch sensing
• evaluation method