What a touchscreen is
A touchscreen combines a display with a sensor that detects where it is touched. Unlike a mouse, it needs no separate pointer: the screen is both output and input. Two sensing methods dominated, capacitive, which detects the electrical properties of a finger, and resistive, which detects pressure pushing two layers together. Other approaches, such as infrared beams across the surface, were also used.
Early prototypes in the 1960s
The earliest capacitive touchscreen is usually credited to E. A. Johnson, an engineer at the Royal Radar Establishment in Malvern, England. He described the idea in a 1965 article and later demonstrated it for use by air traffic controllers, who could select items on a display with a finger. The design could register one touch at a time and used a transparent coating over the screen. It was not widely used outside specialized settings, but the principle underlies later capacitive screens.
Other groups also explored touch input in this era, and dates in the early literature can be uncertain. It is better to say that touch was developed in several places during the 1960s and 1970s than to give one inventor sole credit.
Educational and commercial steps
In 1972, the PLATO IV terminals at the University of Illinois, used for computer-based education, included an infrared touch panel so students could answer by touching the screen. Infrared grid systems like this detect which beams are blocked by a finger, so they work with gloved or bare hands.
Resistive touchscreens grew out of work by Samuel Hurst and colleagues, who founded Elographics in the 1970s. The principle is simple: two conductive layers meet where pressed, and the electronics calculate the position. Resistive panels were cheap and could be used with a stylus, a pencil or a gloved hand, which suited industrial controls, cash registers and kiosks.
In 1983 Hewlett-Packard sold the HP-150, a personal computer with an infrared touchscreen. It was a notable product, but holding an arm out to touch a vertical screen proved tiring, and applications built around a keyboard and mouse had little reason to use touch.
Multi-touch research
Systems that sense more than one finger at once were developed in research labs. At the University of Toronto, the Input Research Group, with Bill Buxton and others, built a multi-touch input device in the early 1980s. Other groups explored touch tables and gesture ideas through the following decades. The company FingerWorks made multi-touch keyboard pads in the early 2000s, and Apple acquired it in 2005. A pinch-to-zoom gesture seems obvious today, but it depended on this long line of experiments.
Stylus handhelds and early phones
By the 1990s, small devices were commercial. The Apple Newton of 1993 and its handwriting recognition drew criticism for errors, though it showed the appeal of pen input. The Palm Pilot of 1996 used a resistive screen and a simplified handwriting alphabet, and became a popular personal organizer. Between those two, the IBM Simon of 1994 combined a phone with a stylus-operated touchscreen, and Windows-based pocket computers extended the stylus approach. These devices required a stylus because resistive screens were not precise or responsive enough for comfortable finger use.
The multi-touch era
In 2007, Apple’s first iPhone used a capacitive screen that tracked several fingers, with software designed around finger gestures rather than a stylus. It was neither the first touchscreen phone nor the first multi-touch device, but its combination of hardware, software and marketing changed expectations. Other makers followed quickly, and Android phones adopted similar designs. Tablets became a mainstream product category in 2010 with the iPad, and after that many laptops, kiosks, cars and appliances added touch panels. The result was that smartphones turned touch into the default way to interact with a computer for many people.
Trade-offs
Touch has drawbacks. Fingers cover the thing being pointed at, screens show smudges, and touch controls in cars can distract drivers who would prefer physical knobs. Accessibility needs vary: many people find touch intuitive, while others rely on keyboards or voice. Designers have added haptic feedback, small vibrations that simulate a click, to offer some of the physical feel that flat glass lacks.
A gradual path
Touch was not a single sudden breakthrough. Sensing methods were refined over decades, display and processor costs dropped, and software finally caught up. The pointing devices that preceded it, from light pens to the mouse, and later laptop touchpads, were all part of the same effort to make interaction with computers more direct.