Every kind of
touch-screens whether it’s of mobile phone or tablets or even touch-screen of
desktop screens runs on same principle described below in a very simpler
manner.
In older times the touch screen used a thin
layer of flexible polyester film attached over a coat of glass or plastic.
Other coatings such as criss-crossed or indistinguishable wires are also used
in place of it.
Now when top layer is pressed over the lower
layer with the help of a finger or its stylus, these invisible wires get
intersect with each other thus will interrupt the flow current resulting change
in direction which helps the device in deciding where is the touch located on
screen. Here, a minimum amount of touch needs to apply to observe the result. In
such older kind of touch screen technology, the sensitivity gets decreasing
towards the edges due to out-dated technology but nowadays capacitive touch-screens
are available which uses its smart technology so that the sensitivity of the
touch screen remains constant & uniform through the screen.
In this technology, a capacitive film is
place over the main screen, holds current which is purposely flown for this
technology. Now when this film is touched by finger or stylus, this reduces the
amount of current flowing at the contact point of screen.
Now
as we know that there is nothing like invisible wires pressed hence, due to the
capacitive screen can locate the contact point sensitively such that it is
uniform throughout the screen with a slightest touch. Signals travel from the
touch screen to the processor as electrical impulses. The processor uses
software to analyze the data and determine the features of each
touch. This includes size, shape and location of the affected area on the
screen. If necessary, the processor arranges touches with similar features into
groups. If you move your finger, the processor calculates the difference
between the starting point and ending point of your touch. The processor uses
its gesture-interpretation software to determine which gesture you made. It
combines your physical movement with information about which application you
were using and what the application was doing when you touched the screen.
The
processor relays your instructions to the program in use. If necessary, it also
sends commands to the iPhone's screen and other hardware. If the raw data
doesn't match any applicable gestures or commands, the iPhone disregards it as
an extraneous touch.
All
these steps happen in an instant -- you see changes in the screen based on your
input almost instantly. This process allows you to access and use all of the
iPhone's applications with your fingers.
Written By
A.Devasena
Associate
Professor/ ECE Dept.
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