Think all capacitive touchscreens are the same? Think again. Capacitive has become the world’s leading touchscreen technology. It’s used in more smartphones, tablets and human machine interfaces (HMIs) than all other touchscreen technologies. While all capacitive touchscreens use a similar method to detect touch commands, though, they are available in different types.
The most basic type of capacitive touchscreen is surface capacitive. Like with other capacitive touchscreens, surface capacitive touchscreens feature an insulator layer. The insulator layer is the top layer, and it’s usually made of glass or plastic. Surface capacitive touchscreens are distinguished from other capacitive touchscreens by their use of a single conductive coating.
The conductive coating is only found on one side of the insulator layer. The other side of the insulator layer is responsible for holding a voltage. When you touch the insulator layer, your finger will absorb some of the voltage. The surface capacitive touchscreen will identify this voltage drop as a touch command.
There are also projected capacitive touchscreens. Projected capacitive touchscreens feature rows and columns of conductive traces. This design results in a grid of thousands of individual keys. The areas where the rows and columns intersect are keys.
When compared to surface capacitive, projected capacitive offers a higher level of accuracy. It can pinpoint exactly where touch commands are performed with greater accuracy thanks to its rows and columns of conductive traces. Some projected capacitive touchscreens are even able to detect touch commands performed while wearing thin gloves. Surface capacitive touchscreens, on the other hand, typically require direct contact with a bare finger – or with another conductive object – to register a touch command.
Mutual capacitive is a subtype of projected capacitive touchscreen technology. Mutual capacitive touchscreens feature rows and columns of conductive traces just like projected capacitive touchscreens. When a voltage is applied to the insulator layer, a capacitor is formed where each of these traces intersect.
Mutual capacitive touchscreens receive their namesake from the way in which the capacitors hold a charge. The capacitors hold a charge because they are close together. When you perform a touch command, your finger will absorb some of the voltage from the nearest capacitor. The voltage of that capacitor will decrease, and the mutual capacitive touchscreen will respond by registering your touch command. Along with surface capacitive and projected capacitive, mutual capacitive is one of several types of capacitive touchscreen technologies.