Touchscreen

The concept of a touchscreen dates to 1965, when E.A. Johnson of the Royal Radar Establishment in the UK described a capacitive touch display in a short article¹. Johnson later built a working prototype in 1968. In 1972, he filed a patent for a capacitive touchscreen, which became the basis for many later designs. The first resistive touchscreen was developed by George Samuel Hurst in 1971, who founded Elographics (later Elo TouchSystems) to commercialize it. These early devices were used in specialized applications such as air traffic control and industrial control rooms. The HP-150, released in 1983, was one of the first commercial computers with a touchscreen, using infrared sensors around the screen. However, it was not until the 2000s that touchscreens became mainstream, driven by advances in capacitive sensing and the launch of the Apple iPhone in 2007, which popularized multi-touch gestures and changed the user interface paradigm².

Touchscreens operate on several physical principles. Resistive touchscreens consist of two flexible layers separated by a gap; pressure forces them into contact, creating a voltage drop that is measured to determine the touch location. They are inexpensive and can be used with any object, but they suffer from lower clarity and require pressure. Capacitive touchscreens, the most common today, use a glass panel coated with a transparent conductor (usually indium tin oxide). When a finger touches the screen, it disturbs the electrostatic field, and the change in capacitance is detected. Capacitive screens support multi-touch and are highly responsive, but they require a conductive stylus or bare finger. Other technologies include surface acoustic wave (SAW), which uses ultrasonic waves, and infrared (IR) touchscreens, which detect interruptions in an IR grid. Each has trade-offs in durability, cost, and environmental tolerance, making them suitable for different applications from ATMs to military displays.

Touchscreens have transformed consumer electronics, particularly smartphones and tablets, enabling direct manipulation of digital content. They are also integral to public kiosks, point-of-sale systems, ATMs, and self-service checkouts. In healthcare, touchscreens are used in patient monitoring and electronic health records, with designs that can be operated while wearing gloves. In industrial settings, resistive touchscreens are favored for their resistance to dust and moisture. Touchscreens have also enabled new forms of accessibility, such as assistive technologies for users with motor impairments. The rise of touchscreens has influenced interface design, leading to the development of gesture-based interactions and haptic feedback. In education, interactive whiteboards and tablets have changed classroom dynamics. The global market for touchscreens continues to grow, with innovations in flexible and foldable displays expanding their use in wearables and automotive dashboards³.

Beyond the familiar smartphone, touchscreens have a rich history of niche applications. The first touchscreen was used in air traffic control, not consumer devices. In the 1980s, the PLATO IV computer system used a plasma display with a touch panel for educational purposes. The HP-150's infrared touchscreen was notoriously unreliable because it could be triggered by dust or bright light. In the 1990s, touchscreens were used in the first Palm Pilots, which relied on a resistive screen and a stylus. A lesser-known fact is that the term "touchscreen" was first used in a patent by E.A. Johnson in 1965. Another edge case is the use of touchscreens in extreme environments: for example, the International Space Station uses touchscreens that must be operable with gloved hands, leading to the development of specialized capacitive screens. Additionally, some touchscreens can detect hover, allowing users to interact without physical contact, a feature used in some Samsung phones and Microsoft Surface devices. Finally, the concept of "force touch" or "3D Touch" introduced by Apple in 2015 allowed the screen to distinguish between different levels of pressure, adding a new dimension to interaction⁴.

Capacitive touchscreen

A touchscreen that detects changes in capacitance when a finger touches the screen, supporting multi-touch.

Resistive touchscreen

A touchscreen that uses pressure to bring two layers into contact, measuring voltage changes.

Multi-touch

The ability of a touchscreen to recognize multiple simultaneous touch points, enabling gestures like pinch-to-zoom.

Stylus

A pen-like tool used to interact with a touchscreen, often for precision tasks.

Indium tin oxide (ITO)

A transparent conductive material used in capacitive touchscreens.