Understanding Touchscreens: The Science Behind the Surface

When touch screens started getting popular, I remember watching this video in which a 5-year-old was told that.. “it’s magic”, there is a magician trapped in the device which shape shifts everything on the screen when we swipe it. That was actually humiliating, but now we are a long way from the use of touchscreens. So it’s important we know the basic working of our touch screens. Sorry, its not ‘magic’ is the work of ‘Electronics’. 

 

This article is focused on two types of touch screens “Capacitive touch screens” and “Resistive touch screens”.

 

 

*Capacitive Touch Screens Capacitive touch screens work by detecting any conductive element (Our fingers act like conductors). These screens are made up of a number of conductive layers and are covered by a protective layer of glass (Gorilla glass touch screens are the most protective). When the screen is touched using a conductive element at any location, a circuit is completed for that location. Further more there are two types of Capacitive touch screens.

 

 

1) Surface Capacitive: It comprises of sensors aligned at the corners of the touch screen, the surface is covered evenly with a transparent conductive material. The location of the touch is registered by the ratio of the flow of current to the cornered electrodes.

 

 

2) Projected Capacitive: This comprises of a grid system containing two electrodes named X and Y. When a conductive element touches any panel on the grid, its electric field changes and the sensors can automatically detect the location of the touch.

 

 

*Resistive Touch Screens: These screens actually require that pressure is applied; for example the ATM touch screens, if you don’t apply enough pressure no input will be detected.

 

A Resistive touch screen contains two conductive layers. A Resistive layer and a conductive layer both separated by equally spaced dots creating air gaps between the layers. When pressure is applied at any point, it causes the outer screen to bend in to touch the other conductive screen, this causes a change in the flow of current. Hence the location of the touch is automatically detected by sensors.