How touch screen work?

Different kinds of touch screen work in different ways. Some can sense only one finger at a time and get extremely confused if you try to press in two places at once.Others can easily detect and distinguish more than one key press at once.These are some of the main technologies:

1.Resistive

These are the most basic and common touch screens,the one used at ATM and supermarkets,that require an electronic signature with that small grey pen.These screens literally "resist" your touch; if you press hard enough you can feel screen bend slightly.This is what makes resistive sreen works-two electrically conductive layers bending to touch another,as in this picture.

2.Capacitive

Unlike resistive touch screens, capacitive screens do not use the pressure of your finger to create a change in the flow of electricity.Instead, they work with anything that holds an electric charge-including human skin.(yes,we are comprised of atoms with positive and negative charges!)Capacitive touch screens are constructed from materials like copper or indium tin oxide that store electric charges in an electrostatical grid of tiny wires ,each smaller than a human hair.

There are two main types of capacitive touch screens-surface and projective.Surface capacitive uses sensors at the corners and a thin evenly distributed film across the surface(as pictured above) whereas projective capacitive uses a grid of rows and columns with a separatechip for sensing.In both instances,When a finger hits the screen a tiny electrical charge is transferred to the finger to complete the circuit,creating avoltage drop on that point of the screen.The software processes the location of this voltage drop and orders the enusing action.