Capacitive touchscreens are found nearly everywhere. From smartphones and tablet computers to point-of-sale (POS) systems and human machine interfaces (HMI), they offer an effective solution for detecting touch commands. Capacitive touchscreens, of course, receive their namesake from the way in which they detect touch commands. Rather than using pressure, they use capacitance to identify when and where touch commands occur. There are four unique types of capacitive touchscreens, however, each of which works in a different way.
#1) Mutual Capacitive
One of the most common types, mutual capacitive touchscreens work on the principle that when multiple conductive objects are close together, they can hold an electrical charge. They are designed with a grid of intersecting capacitors on the display interface. A voltage is then projected into these capacitors. When you touch or tap the display interface, the mutual capacitance around the appropriate capacitors will reduce. The mutual capacitive touchscreen will then register this as a touch command.
In addition to mutual, there are also self-capacitive touchscreens. Self-capacitive touchscreens feature a similar design as their mutual counterparts, with both types consisting of a grid-like arrangement of capacitors. The difference between them is that the columns and rows of mutual capacitive touchscreens work together, whereas those of self-capacitive touchscreens work independently of each other. Self-capacitive touchscreens, unlike most mutual capacitive touchscreens, support multi-touch functionality.
Another common type of capacitive touchscreen technology is surface. Surface capacitive touchscreens are arguably the simplest. They feature an insulator layer with a conductive surface. During operation, a voltage is projected onto the conductive coating of this layer, thereby creating a uniform electrical field. When a bare finger or other conductive object comes into contact with this mildly electrified layer, it forms a capacitor. The surface capacitive touchscreen is then able to detect where the touch command occurred.
A projected capacitive touchscreen, also known as PCT or PCAP, is a newer and more advanced type of capacitive touchscreen. Of all the four capacitive technologies listed here, it’s the most accurate. What is a projected capacitive exactly? Like mutual, self-capacitive and surface, projected capacitive is a type of touchscreen technology that measures capacitance to detect touch commands. Projected capacitive is unique, however, because it uses artificial intelligence (AI) to detect where touch commands occur.
Technically, mutual and self-capacitive are variants of projected capacitive touchscreen technology. They feature a grid of conductive traces that are etched onto the device’s top layer. Projected capacitive offers a superior level of responsiveness as well as accuracy when compared to other technologies.