Touch-Screen Technology

You must have seen touch screens at ATMs, cellphones, information kiosks .Touch screen based system allows an easy navigation around a GUI based environment.

    

Tap on the screen twice for  double clicks, and drag a figure on the screen to move the cursor .We can do almost everything the mouse does, and do away with the additional device(mouse) leaving only the screen.

So “They’re all the rage, they are the buzzword, they are probably the hottest thing in technological cosmos right now!”Falling price and improved technology has fueled the use of these devices in smaller consumer devices like mobile, Tablet PCs and handheld gaming consoles.

The components

There are four popular touch screen   technologies but all of them have three main components.

·        Touch sensitive surface

·        The controller

·        The software driver

 

>>   The   touch sensitive surface is an extremely durable and flexible glass or polymer touch response surface, and this panel is placed over the viewable area of the screen. In most sensors there is an electric signal going across the screen, and a touch on the surface causes change in the signal depending on the touch sensor technology used .This change allows the controller to identify the location of the touch.

>> The controller is a device that acts as the intermediate between the screen and the computer .It interprets the electrical signal of the touch event to digital signal that computer can understand.  The controller can be placed with the screen or housed externally.

>> The software driver is an interpreter that converts what signal comes from the controller to information that the operating system can understand.

Touch screen sensor technologies

Resistive touch screens

Resistive touch screens have two glasses or acrylic layers, one of them is coated wit is conducting and other is coated with resistive material. When these layers brought in contact the resistance changes and change is registered and location of touch is calculated.

These are durable and resistant to humidity and liquid spills. But they offer limited clarity, and the surface can be easily damaged by sharp objects.

Capacitive touch screens

In these devices a glass panel with a coat of charge storing material on its surface .When the panel is touched, a small amount of charge is drawn at the point of contact. Circuit located at each corner of the screen measure the difference in charge and send information to the controller for calculating the position of touch.These are used where the clarity precision is of concern as in laptops and medical imaging