2D Capacitive Touchscreen Grid Sensing Simulator

Electrode Grid

Grid density 14 × 9

Touch Model

Contact strength 1.0

Field falloff radius 14 mm

Sensor noise 0.02

Drag either dot on the grid to move a finger contact.

Controller Readout

Touch 1 detected

—

Touch 2 detected

—

Localization error

— mm

Scan rate

— nodes/frame

How it works

A capacitive touchscreen is a fine grid of transparent row and column electrodes separated by a thin dielectric. At rest, every row/column crossing (a "node") holds a small fixed mutual capacitance — an electric field bridges the gap between the two electrodes.

A finger is a grounded conductor. When it comes close to a node, it diverts part of that field to ground, reducing the mutual capacitance measured at nearby crossings. The effect falls off sharply with distance — modeled here as roughly inverse-square in the 3D field, so only nodes within a couple of centimetres of the actual contact show a meaningful drop.

The controller scans every node (rows driven one at a time, columns read out), builds a 2D capacitance map, and finds local dips below a detection threshold. Because several neighbouring nodes all dip a little, a weighted centroid of the dip around each local minimum gives sub-pixel position accuracy — far finer than the physical electrode pitch. Two simultaneous dips that stay separated let the same scan resolve two independent touches at once.

Drag the two dots — capacitance grid updates live

Strong capacitance drop Baseline capacitance Reconstructed touch position