A touch screen or touch sensor is a combination of an input and output unit. The touch screen itself is usually on top of an integrated data processing unit (IDU) or touch screen display. The screen is most often either an LCD or LED touch screen while the unit is most often a smartphone, tablet, or laptop. Touch screen technology is still evolving and growing at a rapid pace and new devices are coming out all the time with more capabilities than ever before.
Touch screens generally consist of a touch sensitive surface that detects the light waves from your fingers and uses this information to produce an image. Your fingers are connected to a pair of transducers which are each designed to detect light wave frequencies. When you touch the screen the transducers send electric signals to the integrated circuit on the screen. Your finger then interacts with the screen by making contact with either one of the transducers or with the entire screen. This interaction of your finger with the touch screen activates the LED backlight behind the screen which then lights up the screen causing it to display an image.
The typical touch screen tablet devices will have the display screen itself, along with a touch sensitive membrane called a capacitive sensor. When your finger makes contact with either part of the touchscreen the electrical signal generated causes the LED light to turn on. The LED backlight is powered by the charge that is left in your finger when you touch the screen. Many modern touch screen tablets use resistive or capacitive technologies to allow the user to either interact with the screen through physical touch or through some sort of infrared movement that causes the LED light to turn on.
To make sure that the capacitive sensor is not activated by your finger or any other moving object, the screen is designed to have a dead zone around it. This dead zone is different from the normal areas of the touch sensitive screen that light up when your fingers actually make contact with the screen. The deadzone is a special area of the touch screen that acts like a fingerprint. When you place your finger into this area the electric signal is not triggered and the LED backlight will not turn on.
Capacitive or resistive touchscreens are generally more popular than the former due to their increased sensitivity and mobility. Capacitive touchscreens require that there is some movement on the part of the person touching the screen in order for them to make actual contact. In order for a capacitive touch screen to really work you must have smooth skin. The problem with capacitive touchscreens is that they can be used with wobbly fingers because they respond so well to even very slight movements. This can make it difficult to use them on wobbly fingers, especially if you are trying to type on the touchscreen.
Resistive touch screens are generally more expensive and heavier since they have to include a built-in resistive layer that translates the pressure from your finger onto the screen. Although they are more expensive they are easier to use on heavier phones. They also do not have the sensitive fingerprint configuration that capacitive touch screens do, and although they do work better on smoother skin, they can be quite a handful to take on an oversized finger. A stylus can come in handy sometimes when trying to push a touch screen with a large finger.