Friday, 9 August 2013



Many of us are using Touch Screen mobile phones.
Have you ever thought of what is inside it???
How it is working???
Whether it will sense any kind of material???
Here is the answer for such a kind of questions.....

Touch Screen Monitors are of three Basic types
                Surface Acoustic Wave


The resistive system consists of a glass panel with two layers.
One is Conductive layer and other is Resistive layer.
Conductive layer is the base layer above that resistive scratch layer is placed.
These two layers are separated by spacers (like a vacuum layer not exactly).
An electrical current runs through these two layers.
When a user touches the screen, the two layers make contact with each other and the electric current changes in that place.
The change in the electrical field is noted and the coordinates of the point of contact are calculated in order to know the exact location of the touch.


Before knowing about capacitive touch you should know what a capacitor is.
Capacitor is a storing device that stores electrical charge.
In the capacitive system, a layer that stores electrical charge is placed above the glass panel.
Because of the layer of electrical storage it is called capacitive touch.
When a user touches the screen, the charges in the capacitive layer decreased.
It is because our body is a conductor when we touch the screen small amount of charge get into our body.
 Hence the charge in the capacitive layer decreases.
By the decrease of charge we can know the exact location of touch.


On the glass panel of surface acoustic wave system, two transducers are placed.
Reflectors are also placed on the glass panel, they reflect electrical signal from one transducer to the other.
When a user touches the screen, the signal that is being reflected will be disturbed.
With the location of disturbance we can find the exact place of the touch.


When comparing all the three systems, surface acoustic wave is the best one.
Because it won’t absorb any light, so that 100 percent throughput is achieved.
It has perfect image clarity.
Capacitive touch has about 90 percent throughput whereas resistive touch has 75 percent.
And other important feature of capacitive touch is that it will work only if it is tochues by conductor.
All the other systems can be touched by any material.

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