Touch screen is an electronic display that can be touched to manipulate a computerized device. The user may touch the screen with the fingers or with a penlike tool called a stylus. Touch screens are common in cellular telephones, tablet computers, and video game systems. Waiters use touch screens to take orders in many restaurants. Banks offer touch screens on automated teller machines (ATM’s). A touch screen can be simpler and more direct to use than a computer mouse or keyboard.
How touch screens work.
There are four main kinds of touch screens. They are (1) capacitive screens, (2) resistive screens, (3) infrared screens, and (4) surface acoustic wave screens.
Capacitive screens generate a layer of electric charge. The human body conducts electricity. As a result, touching the screen with a bare finger causes a small charge to move from the screen to the finger. The charge is too weak for people to feel, but sensors in the screen register such changes. In some cases, an electrically conductive stylus can be used instead of a finger.
Resistive screens measure the pressure of touch. Electrically conductive layers within the screen convert the change in pressure to an electronic signal.
Infrared screens create an invisible grid of infrared light on the screen. Touching the screen disturbs the grid, and the computer tracks the disturbance’s location.
Surface acoustic wave screens generate a layer of sound waves across the screen’s surface. Sensors measure how these waves are disturbed when the screen is touched.
History.
E. A. Johnson, a British inventor, is often credited with developing the first touch screen in the mid-1960’s. It was a capacitive device used by the United Kingdom’s Royal Radar Establishment. Touch screen ATM’s were introduced in the 1980’s. During the 1990’s, handheld computers called personal digital assistants (PDA’s) often used touch screens and styluses. Apple Inc.’s iPhone, a computerlike cellular telephone first released in 2007, introduced many consumers to capacitive touch screens.
