How a capacitive touchscreen works
Your phone's screen is a solid sheet of glass, and under it sits a grid of see-through electrodes: rows on one layer, columns on another. A tiny controller chip pulses one row at a time, and its electric field arcs up through the glass into each column; your fingertip conducts and steals some of that field, so a few crossings dip. Weighing those dips, the chip finds their center, finer than the grid itself, and because every crossing is read on its own, it can track several fingers at once. The grid never feels you press, so a thick glove fails: it keeps your finger too far away to steal the field.
- 0:00 The tap
- 0:07 Exploded stack
- 0:18 One crossing, cut open
- 0:33 Fingertip steals the field
- 0:40 The scan
- 0:48 Find the center
- 0:55 Many fingers, thick glove
- 1:04 It feels the field