Touchless sensor - QuickField simulation example
Touchless sensor consists of two groups of electrodes on the sides of the rectangular dielectric frame. Tx - transmitter, with voltage applied, Rx - receivers. Rx potential depends on the position of the finger near the sensor.
How to calculate the effect of finger position on the receiver-electrode potentials of a touchless sensor?
Answer Typical applications Geometry
Distance between the finger and the sensor surface is 50 mm.
Given
Task
Solution
Results
Electric field distribution in touch sensor:
Engineering question
Ground the finger, treat the Rx electrodes as floating, and solve a series of 3D electrostatic models to obtain Tx–Rx potentials at each position.
capacitive proximity sensors, hover sensing electrodes, noncontact sensing panels
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Simulation problem
Problem Type
3D problem of electrostatics.
Relative permittivity of dielectric ε= 4.7
Tx voltage +1V, Rx - floating, finger is grounded.
Determine Rx electrodes potential for various finger positions.
Real sensor operates at AC voltage and the potential difference between Rx and Tx electodes are measured. As materials conductivity is almost zero we can safely ignore active component of the electric current and switch to the electrostatic analysis.
A set of problems is simulated with different finger positions. Due to the model symmetry we simulate only the cases where thefinger placed in the top left quarter of the sensor window. QuickField calculates the average surface potential for each of Rx electrodes.
Electrodes potential (Tx-Rx) for different finger x-position at y = .
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