Many engineering projects developed now-a-days involves touch panel screen. Different algorithms are implemented to sense the location on different touch panels appended below: Algorithms will be discussed later.
In todays post, I will discuss types different technologies that are commonly used in touch screen. A touch is an electronic display that can detect the location of a touch. Touch usually refers to touching the device with hand or pen. These touch panels are used widely in HMIs, PDA and other devices etc.
Following are the different technologies most widely used :-
- Resistive: Resistive touch screen consist of different layers of which important two layers metallic conductors. Whenever a user touch the panel these two metallic layers behaves as voltage divider and thus causing a change in electric current. This change in electric current is sense by the controller for processing.
- Surface Acoustic Wave: In Surface Acoustic Technology, whenever a user touch the panel, a portion of a wave is absorbed, which is used to sense the position and send to controller for processing
- Capacitive: An insulator covered with a transparent conductive layer can behave as capacitive touch screen. When a user touch the panel, electrostatic field of the body gets disturbed which is measurable as the change in capacitance.
- Infrared: Infrared touch screen is simplest to understand. There is X-Y array of Infrared sender and receiver. Whenever a user touch the panel, the disturbance in array sense the position. From X-Y, I mean the two different perpendicular directions.
- Optical Imaging: This is recent technology, getting popular these days. Mostly couple or two image sensors are placed to detect the location of the touch.
- Disperse Signal Technology: Came into existence in the year 2002, that detects the mechanical energy of a glass that gets change during the touch. The technology claims that this touch screen is also unaffected by the dust and scratches.