Technical overview about capacitive sensing vs. other touchscreen-related technologies
Not all touch screens are created equal. Ever since the first touch screens came into being as part of an effort to improve the technology of air-traffic control systems, there have been many versions. In 1972, students at the University of Illinois developed an optical touch screen for computers that linked an array of predetermined points in a matrix. A year later, George Samuel Hurst filed for a patent for the first resistive touch screen. Capacitive touch screens, at least in theory, are at least eight years older than either the optical or resistive technologies. E.A. Johnson wrote a paper in 1965 that outlined his theories and body of work on capacitive touch screens.
What are the Differences?
Capacitive touch screens react to the touch of something that has capacitance. In most cases, this is the skin of someone's finger. Otherwise, it's something artificial that mimics the capacitance of human skin, such as a specially designed stylus. Sensors inside the device detect the change in electric charge and react accordingly. Projected capacitance is even more accurate because it forms a triangulated grid around the point of touch. Additionally, the extra accuracy allows for the use of screen protectors or heavy-duty screens, such as Gorilla Glass.
Multi-touch screens were the biggest innovation in the industry. They allowed users to manipulate more than one input at a time. "Pinch to zoom" is the most famous application of multi-touch. Multi-touch screens also allow for gestures to complete preassigned tasks, such as performing a character's specialty moves in a computer game or app.