Question How does a touch screen work?

Answer

By using your finger to disrupt an electrical current.

Touch screen technology has become part of our everyday lives. We barely bat an eye while scrolling through Instagram or liking a friend’s post on Facebook. But how does putting a finger on your phone’s screen to perform these tasks actually work?

There are three components that work together to create the magic of touch screen capability: the touch sensor, the controller, and the software.

The touch sensor can be one of three types: resistive, surface acoustic wave, or capacitive. Resistive and capacitive are the most common and are quite ingenious. In resistive systems, two “metallic layers become connected” which causes a “change in the electrical current…which registers as a touch screen event that is sent to the computer controller for processing” and can be used with either fingers or a stylus. In contrast, capacitive systems use a layer of capacitive material which changes the amount of electrostatic charge at the point where contact has been made and only work with fingers. In surface acoustic wave systems, sound waves are sent across the surface glass, but become absorbed when touched with a stylus.

The controller determines the location of the stylus based on this absorption. The controller takes the information from the sensor and determines where exactly the touch has taken place. This information is then sent to the software, which reacts to the touch. This may seem like a long process, but it takes nanoseconds in real time.

What are some examples?

Examples of touch screen technologies range from the smart phone that is very likely in your pocket, to bowling alley scoring systems, to digital cameras, to self-ordering kiosks at your local McDonald’s.

In recent years, they have grown more popular as self-checkout kiosks in libraries, grocery stores, and drug stores. Interactive whiteboards use a projection displayed onto the surface where the image can be manipulated using hands or a pen tool. E-book reading devices such as the Nook or Kindle, where the user touches the interactive screen to move through the pages, offer book lovers a way to cart around a multitude of items without the heft of physical tomes.

Interesting facts about touch screens:

• E.A. Johnson is credited with creating the first touch screen system circa 1965-67. His findings were published in 1968 regarding touch screen technology and air traffic control.
• The Simon Personal Communicator, launched in 1992 by IBM, was the first touch screen telephone. In addition to making telephone calls, it could send emails and faxes and had a calendar and clock, among other features.
• An engineer at Elo Touch Systems named Bill Colwell developed the first curved glass touch screen interface in 1977. This was the first time a device was ever said to have “touch screen” technology.
• The first patent that featured touch screen technology was granted to George S. Hurst, Jr. and William C. Colwell on October 7, 1975.
• Every device that uses touch screen technology has a touch screen driver. This computer program is what turns the touch into a command within the computer.
• In the 1980’s General Motors introduced the first touch screen technology into its vehicles but due to high repair costs it was soon taken off the market.
• By 1973, CERN (European Organization for Nuclear Research) was using a touch screen computer to control a particle accelerator.

Published: 11/19/2019. Author: Science Reference Section, Library of Congress