Touchscreen

Touchscreen

A touch screen is a computer device that manages both display and pointing by replacing the mouse with a finger or a stylus. It allows to select some of its areas by contact

 Touchscreen © PEXELS 

Usage and history of touch screens

The use of touch screens has been popularized by the advent of smartphones and tablets. There are also touch screens in many other devices such as GPS, media players, laptops or desktops, video game consoles or kiosks.

While Apple has largely contributed to the rise of touch screens with the release of the iPhone in 2007, work on this technology date back to the 1950s with the creation of the first capacitive sensors by the Canadian musician Hugh Le Caine. The next decade saw the first touch screen based on infrared technology designed by researchers at the University of Illinois (USA). An innovation taken over by IBM who will market it in a computer called PLATO IV (Programmed Logic for Automated Teaching Operations) in 1972.

There are several touch screen technologies. Discover below the most common ones.

Resistive touch screen

The resistive touchscreen was invented in 1971 by then-researcher Sam Hurst at the Oak Ridge National Laboratory. He founded the company Elo TouchSystems which, even today, is a major player in the tactile technologies market. The operation of the resistive touch screen rests on two conductive layers separated by a space. The pressure of the finger or of a stylet puts the two conductors in contact, which has the effect of circulating a current. Horizontal and vertical plates integrated with the borders of the screen make it possible to determine the position of the finger or the stylus by measuring the tension on each axis. Reasonably simple in their operation, resistive touch screens have a short life span that does not exceed 10 million impacts.

This diagram illustrates the operation of the resistive touch screen. Two conductive layers (# 4 and # 2) separated by microscopic wedges (# 3) are placed on a glass. When the user presses with his finger or a stylus, it causes contact between the two conductors, which has the effect of circulating a current. Horizontal and vertical plates integrated with the borders of the screen make it possible to determine the position of the finger or the stylus by measuring the tension on each axis.
© Mercury13, Wikimedia Commons, CC by-sa 3.0

Capacitive touch screen

A capacitive screen consists of a glass covered with a transparent conductor, usually based on indium tin oxide. As the human body is also electrically conductive, when a finger lands on the surface, it creates a disturbance of the electrostatic field of the screen that can be measured. Measuring systems located at the four corners of the screen detect the value of this pressure drop and the comparison between the four sensors indicates the location of the point of contact. One of the technical advantages of this type of screen over resistive technology is that it offers greater transparency. However, it can not be used with gloves.

Infrared screen

Infrared transmitters and receivers are arranged all around the screen frame to form a frame invisible to the eye above the glass. When the user places his finger on the screen, he cuts the beam. This point of impact is measured by a controller on a horizontal axis and a vertical axis. The infrared touch screens are very resistant and generally used on terminals intended for intensive use.

Multipoint touch screen

We talk about multi-touch screen when it is able to detect the support of several fingers simultaneously. This process was invented in the early 1980s by a researcher at the University of Toronto (Canada). In 1983, Hewlett Packard released the HP-150, the first computer with a multi-touch screen.

This technology is now widespread on mobile devices and computers because it allows tactile gestures that allow you to perform elaborate actions such as pinching or spreading your thumb and forefinger to enlarge or shrink an image.