Design And Function Of A Capacitive Touchscreen

The main application for capacitive touchscreens has, to date, been in smart phones. The display reacts to the touch of a finger, instead of only reacting to pressure applied to the screen, as in the case of a resistive touchscreen.

Each intersection on the grid acts as a capacitor, because the metal oxide strips line up exactly opposite the capacitor layer. An electrical field is created between them whenever an electrical voltage is applied to the layers.

Just like a capacitor, the grid points have a specified electrical capacity.

When a finger touches the surface, the electrical field at the intersection and its capacity is affected by the user's electrical charge. This leads to a change in the charge at the ends of the conducting strips. The evaluation electronics determine the coordinates of the point touched on the touchscreen.

Advantages

The electronics can recognize several separate touch events. It reacts more quickly. It is not necessary to calibrate the touchscreen.