Touch Screen Technology and Its Types

TOUCH SCREEN TECHNOLOGY AND TYPES OF TOUCH SCREENS

A touchscreen is an easy to use input device that allows users to control the system by touching the display screen. A touch system consists of a touch sensor that receives the touch input, a controller, and a display unit. The most commonly used touch technologies are the capacitive and resistive systems. The other technologies used in this field are infrared technology, near field imaging and SAW (surface acoustic wave technology). These technologies are latest in this field but are very much expensive. A little note on resistive and capacitive touchpad is as follows.
Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water.
Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus. Capacitive touch screens are not affected by outside elements and have high clarity.
The graphic LCD that we have used here is OMG12864. It is a 126x64 pixel graphic LCD module having inbuilt controller. A LCD consists of a liquid-crystal material that behaves electrically as a capacitor. There is a set of two transparent panels with a liquid crystal solution between them. Light is shined from behind the panels. Each crystal either allows light...