How does the touchscreen work?
(A) A slight voltage is applied to four corners of the screen. Electrodes spread out the voltage, creating a uniform voltage field. When your finger makes contact with the screen’s surface, it ‘capacitively couples’ with the voltage field, drawing a minute amount of current to the point of contact. The current flow from each corner of the screen is proportional to the distance to your finger. A controller card measures the ratios of the current flows and thus locates where your finger touched the screen.
