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The Touchscreen Technology in Mobiles Phones

Technology has evolved from the wheel to Juno and from the slate to the touchscreen. Imagine having the world at your fingertips. Well, you no longer need to imagine because you have lived it all; each of us is well acquainted with the marvel of touchscreens.

A touchscreen is a display screen that is sensitive to the touch of a finger or stylus. With applications in ATMs, retail point of sale terminals, car navigation systems, medical monitors and industrial control panels, it has revolutionized the Human Machine Interface (HMI). But it’s most prominent use is in mobiles; particularly smartphones.

In the initial days of the advent of the smartphone, manufacturers used the resistive touch technology. The resistive touchscreen consists of a flexible top layer made of Polyethylene (PET) and a rigid bottom layer made of glass. Both the layers are coated with a conducting compound called Indium Tin Oxide (ITO) and then spaced with spacers. When you touch the surface, the flexible screen presses down and touches the bottom layer. The human body is electrically conducting, so a change in the electrical current is detected at the point of contact. The coordinates of this location are detected and then the subsequent operations are carried out.

Thanks to innovations, the resistive technology has been replaced with capacitive technology. However, the former still finds uses in screens of larger dimensions. Capacitive touch technology is quite popular nowadays. Introduced by the original Apple iPhones, this grid of tiny, transparent electrodes is now being used by most manufacturers. These vertical and horizontal rows of electrodes overlap to form the capacitor on the screen, which helps to position a touch. Since the human body is an electrical conductor, a touch on the screen can be detected as a change in the electrostatic field.

There are usually three layers in a capacitive touchscreen — the LCD display panel at the bottom, the touch layer in the middle and the cover glass layer on the top. These layers have lead to comparatively thicker phones in the past. Newer technologies such as in-cell and on-cell have evolved because of the increase in demand for slimmer phones. Apart from significantly thinning down the display width, it also helps improve color saturation.

Moving the touch layer onto the outer glass layer is called on-cell or G2 tech. This technology has been used in LG’s upcoming smartphones, Samsung’s Super AMOLED displays as well as Samsung’s high-end phones like Galaxy S3 and Galaxy Nexus. The main challenge of this process is to deposit the electrodes on the cover glass, which is a type of strengthened glass.

Moving the touch sensors into the display panel is called in-cell tech. It is primarily used in Apple’s iPhone5 and Sony’s Xperia P. There are two major challenges associated with this tech. First, the touch sensors would have to use electrodes embedded in the display, which is made of electrodes. It may cause unwanted noise. Second, a defective display can render the entire module out of work. Moreover, the recent thinning down of the cover glass (Gorilla) to 0.5 mm will also result in a significant decrease in the overall width. With newer technologies coming up on the market every day, the tech-savvy generation can hope to see a lot more exciting changes in the upcoming smartphones.

Technology has evolved beyond measure. There are also some inventions which came from the sci-fi masterminds! Read more about them here.

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