Touchscreen

A touchscreen is a display that also senses where a finger or stylus touches it, so a person can control a device by pressing, tapping or swiping directly on the image. It pairs a screen, such as a liquid crystal display or an OLED panel, with a sensing layer that reports the position of each touch to the device’s processor. Touchscreens are found in phones, tablets, laptops, ticket machines, point-of-sale terminals and industrial controls.

History of touchscreens

Some of the earliest practical work came from a particle physics laboratory. In February 1971, CERN’s member states approved the Super Proton Synchrotron (SPS), a particle accelerator with a circumference of nearly 7 kilometers. Wiring every switch and display to a central control room, as had been done for the older Proton Synchrotron, would have been too costly. The controls group instead planned a handful of computer-driven controls whose functions could change on screen.

Touch input was already being tried at accelerators. David Fryberger and Ralph Johnson at the SLAC laboratory had built a device based on acoustic waves traveling across a sheet of glass, which was used for accelerator control in 1971. On 11 March 1972, the CERN engineer Bent Stumpe proposed a capacitive alternative in a handwritten note. It used a set of capacitors etched into a film of copper on glass, designed so that a nearby conductor, such as a fingertip, would raise the capacitance by a measurable amount.

The first working capacitor was made at CERN in 1973, and Frank Beck and Stumpe described the touch screen and a computer-controlled knob in a May 1973 report. The copper lines were about 80 micrometers wide and 80 micrometers apart, fine enough to be invisible. Each button had a capacitance of about 200 picofarads that rose by roughly 10 percent when a finger came close. The change was detected with phase-locked oscillator circuits, which had recently become available on a single integrated circuit. A lacquer coating kept fingers off the capacitors, and a Touch Terminal based on the design was later built for the Antiproton Accumulator.

A university design publication credits Samuel Hurst of the University of Kentucky with a touchscreen prototype called the Elograph and notes that touchscreens became widespread after the first iPhone used one in 2007.

How touchscreens work

Every touchscreen has to answer one question: where on the surface was the screen touched? The sensing layer answers it by watching for a change in an electrical, optical or acoustic signal. A controller turns that change into coordinates, and the device’s software decides whether the touch was a tap, a swipe or a press and hold, and responds on the display.

Because the controls are drawn on the display rather than built from hardware, the same panel can show different buttons, keyboards or languages. This was the idea behind the original CERN work, where a single operator could reach thousands of controls through a few redefinable buttons.

Types of touchscreens

Capacitive screens use the finger, or a conductive stylus, to disturb an electric field created by a transparent conductive coating. Sensors locate the disturbance. They are very responsive and durable because they have no moving parts, but they do not respond to non-conductive objects such as most gloves and can cost more than other sensor types.

Resistive screens have two layers coated with a resistive substance, and pressure makes the layers touch. They cost less, resist grime and electronic interference, and work with anything that applies pressure. They have lower clarity, meaning less precise touch positions, and are common in point-of-sale systems and industrial equipment.

Infrared screens place a grid of infrared light-emitting diodes and photodiodes around the display, and a touch interrupts the beams. They are accurate and suit large displays, but direct sunlight and dust affect them and the sensors require a wider bezel, so they are mostly used indoors. Surface acoustic wave screens send ultrasonic waves across the glass, and a touch absorbs some of the energy. They share many strengths and limits with infrared designs and are sensitive to electronic interference.

Applications of touchscreens

Touchscreens now appear in smartphones, laptops, shopping mall directories, self-service kiosks, cash registers, ticket machines and car dashboards. In industry they replace banks of switches with a single adaptable panel. Large infrared and acoustic screens suit big indoor displays.

The same sensing principles power related devices. The touch pad on a laptop, for instance, uses capacitive and pressure-based systems, and optical touch panels use light sensors to detect the touched area.

Advantages and disadvantages of touchscreens

The main advantage is flexibility. Controls can be redesigned in software, a screen can serve many languages, and fewer physical parts mean fewer things to wear out. Capacitive designs respond quickly and are durable, and direct touch makes devices easy to use without training.

The drawbacks depend on the sensor type. Capacitive panels can be unreliable with gloves, resistive panels are less precise, and infrared and acoustic panels can struggle in sun, dust or electrically noisy settings. Touching a shared surface has also raised hygiene concerns, which is one reason designers are developing touchless options such as proximity sensors that need no full touch, radar-based gesture sensing and haptic feedback that lets users feel a virtual object. Flexible screens, three-dimensional touchscreens and predictive touch driven by artificial intelligence are also in development.

Touchscreens vs. touch pads

A touchscreen and a touch pad both detect touch, but they differ in what they sit on. A touchscreen is the display itself, so the user touches the thing being controlled. A touch pad is a separate surface, usually below a keyboard, that moves a pointer on a screen elsewhere.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 4, 2026Researched and drafted with AI assistanceReport an issue