Buttons on electronic devices are now passé: touch screens are rapidly becoming the ubiquitous interface for controlling them.
While many of us have started using touch screens only after they went mainstream in modern smart phones, the technology itself has been around for decades.
Among other places, touch screens are found in handheld devices used in industrial settings, navigational equipment, retail point of sale terminals, vending machines, kiosks and ATMs.
Touch screen technologies can be mainly divided into two types- overlay based and perimeter based.
In overlay based touch screen technologies, the screen is integral to the mechanics of registering input. Touch events are registered when the object touches the screen.
There are two types of overlay based touch screens:
Perimeter based touch screen technologies work differently. In this case, the screen is incidental to the main process of registering input. These screens have beam break sensors or cameras embedded in the bezel. These sensors monitor light or acoustic waves emitted by LEDs or transducers, also set in the bezel.
When an object touches the screen, there is a break in the path of the rays. This creates a shadow or a dark area which is detected by the sensors. Using complex mathematical calculations, and in some cases heavy data processing the location of the object can be determined.
There are mainly three types of perimeter based technologies:
All of these touch screen technologies can also be integrated on top of a non touch based system like an ordinary LCD and converted into Open Frame Touch Monitors.
ShadowSense is a form of perimeter based technology. It also uses light emitted by LEDs and the shadows thrown by the object to calculate size and location on the screen. However, the implementation is simpler and the screen itself runs without any drivers. ShadowSense touch screens also have numerous other advantages over conventional touch screens.
Read about latest touch screen technology.