How does touch in Smartphone work l Basic Guide

How does touch screen works in smartphone?

Touchscreens In A Nutshell

Although touchscreens are becoming increasingly popular, they are by no means a new invention. The first touchscreen was invented back in the 1960s, and has gone through many changes and iterations to become the touchscreen we use today.

Touchscreens are not limited to smartphones and tablets, they are literally everywhere; from ATM machines, point-of-sale terminals, and navigation systems, to game consoles and even touchpads on laptops. Touchscreens are popping up everywhere, and are slowly taking over our lives, so the least we can do is know a bit more about how they work!

Capacitive touchscreen

As opposed to the resistive touchscreen, which relies on the mechanical pressure made by the finger or stylus, the capacitive touchscreen makes use of the electrical properties of the human body. A capacitive screen is usually made of one insulating layer, such as glass, which is coated by a transparent conductive material on the inside. Since the human body is conductive, which means electricity can pass through it, the capacitive screen can use this conductivity as input. When you touch a capacitive touchscreen with your finger, you cause a change in the screen’s electrical field.

This change is registered, and the location of the touch is determined by a processor. This can be done by several different technologies , but they all rely on the electrical change caused by a light touch of a finger. This is the reason you cannot use a capacitive screen while wearing gloves – the gloves are not conductive, and the touch does not cause any change in the electrostatic field. Same goes for non-capacitive styluses.

Since capacitive screens are made of one main layer, which is constantly getting thinner as technology advances, these screens are not only more sensitive and accurate, the display itself can be much sharper, as seen on devices such as the iPhone 4S. And of course, capacitive touchscreens can also make use of multi-touch gestures, but only by using several fingers at the same time. If one finger is touching one part of the screen, it won’t be able to sense another touch accurately.

Difference between Touch Screens

Its simple generally there are two type of touch screens which are in use today.

Resistive Touch and Capacitive Touch.

Reistive touch are mainly used in ATM machines and some first generation touch mobile phones. Touch screens of this type has two layers, one is a conductive layer another one is a resistive layer. both layers are separated by a small distance. The conductive layer usually has some charged particles in it, when you touch any one of the layers, due to pressure it bends and touch the other layer thereby establishing a connection between the two layers. so a charge from the conductive layer at the point of contact starts to moving into the resistive layer, a sensor detect these movement and recognize the touch.

Capacitive Touch

Capacitive Touch is the widely used in mobile phones these days. Compare to resistive touch capacitive touch is accurate and reliable. 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 electrical charge including human skin. Capacitive touch screens are constructed from materials that store electrical charges in an electrostatic 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 whereas projective capacitive uses a grid of rows and columns with a separate chip for sensing. In both, when a finger hits the screen a tiny electrical charge is transferred to the finger to complete the circuit, creating a voltage drop on that point of the screen. The software processes the location of this voltage drop and orders the ensuing action.

Most of the smartphones use capacitive touch technology.
                       In short our smartphones screen is a big straw of capacitors. And when you touch at a particular spot on your screen, your fingers being conductors change the capacitance of that spot. And the phone detects these changes in capacitance and determines the coordinates of that spot on the screen. This is a vary basic idea of how touch screen now a days work.