Capacitive is one of the leading touchscreen technologies used to make smartphones, tablets, human machine interfaces (HMIs) and other touchscreen devices. It’s called “capacitive” because it relies on the human body’s electrical conductivity to identify and register touch commands. Touching the surface of one of these devices causes your body to absorb some of the device’s uniform electrostatic charge. The device is then able to pinpoint the location of this electrical phenomenon, thereby identifying where you touched. But not all capacitive touchscreen devices function in the exact same way. There are different types of capacitive touchscreen technology, each of which has its own characteristics.
Among the most common types of capacitive touchscreen technology is surface capacitive. With surface capacitive devices, a single side of the insulator layer is coated with a conductive material or ink. The device creates a uniform electrostatic charge that travels through this layer. Upon touching it, the user’s finger or hands absorbs some of the charge. Surface capacitive touchscreen devices are highly accurate and offer a superior image quality, making them a popular choice among businesses and consumers alike.
Pioneered by the Binstead brothers in 1984, projected capacitive touchscreen is a form of touchscreen technology that’s even more accurate than its surface capacitive touchscreen counterpart. The Binstead brothers discovered that by changing the value of each key, they could create a more accurate method for detecting touch commands. Furthermore, projected capacitive devices are more resistant to damage and contaminants than devices powered by other types of touchscreen technology.
Mutual capacitive is actually a type of projected capacitive touchscreen technology. With mutual capacitive touchscreen devices, there’s a row trace and columb trace used to form a capacitor. The device applies a voltage across these rows and columns so that it’s able to detect the user’s touch command. Mutual capacitive touchscreen devices offer the added benefit of supporting multi-touch commands. This means you touch a mutual capacitive device at two simultaneous points — and it will register a touch command at both of those points.
Self-capacitive is also a type of projected capacitive touchscreen technology. Also known as self-capacitance, it’s characterized by independently operating columns and rows of electrodes. Like mutual capacitive, it uses a grid-like array of electrodes. However, the rows and columns operate feature their own uniform electrostatic field. The end result is a stronger electrostatic field than its mutual capacitive counterpart. The downside, however, is that self-capacitive devices don’t support multi-touch commands.