Here we will discuss touch display technology which is an important part of the mobile phone technologies. We are talking about multitouch display which has a rapid growth in the mobile device market. There was a time when we were taping with the help of tiny stylus. But the time changed when apple introduced i-phone and people start wiping fingers across Smartphone screens and performing more that is not the part of previous Smartphone interface. Now the technology grows and we have touch screen which allows us multi touch facility. There are several touch technologies available to engineers. There are 18 different touch technologies available. Some of them rely on infrared light, some use force sensors and some use sound waves. All the technologies have advantages and disadvantages in terms of size, accuracy, durability, reliability and sensitivity to number of touches.
Transparent touch technology has two mostly used technologies in the market. There is a difference between the two technologies one requires the moving parts and other requires solid state. One is based on electrical resistance and other is based on electrical capacitance. One technology is digital which rely on presence and absence of the signal and other is analog which rely on change in the value of the signal. Users have different experiences with these two technologies. Here we will discuss the two technologies one by one.
Resistive touch technology: The traditional touch screens are based on the technology that is analog resistive. These panels work by detecting the change in the resistance to current when you touch at a point. This process involves two layers one above the other, the top layer is a plastic film and the lower one is the glass layer. When you push down the plastic layer of film it comes in touch with the glass and completes the circuit. Both the films are covered with a grid of electrical conductors which can be fine metal wires or a thin film of transparent conducting material. Indium tin oxide is used in most of the cases. The electrodes are at right angle to each other, there are parallel conductors in one direction on the glass screen and are at right angle to the electrodes on the plastic film.
Contact happens between the two grids when you press the plastic film and there is a change in the voltage and the x y coordinates are calculated based on the resistance measure at the contact point. Analog to digital converters create a digital signal after analog voltage processing. Many companies are using Corning’s Gorilla Glass in their products as a protective outer layer for their devices. This glass used in most of the displays is an alumina silicate formulation made up of aluminium, silicon and oxygen. The glass have sodium ions spreaded throughout the material.
At the temperature of about 400 degrees the glass is put in a bath of molten potassium then sodium ions are replaced by the potassium ions. At the surface of the glass more of the sodium ions are replaced by the potassium ions and the exchanged quantity go on reducing as you go deeper into the glass. Sodium has an atomic number 11 while the atomic number of potassium is 19 which mean potassium atoms are larger than sodium atoms so when you replaced the smaller sodium atoms with the larger potassium atoms then the packing arrangement becomes tighter giving more hardness to the glass. You can understand it with a simple example imagine a box filled with tennis balls and the top layer replaced with larger balls then the larger balls will squeeze to adjust in the box and make them difficult to come out of the box.
This makes difficult to break the glass and if someone starts breaking it is less likely to grow through the glass. The strengthening of the glass by ion exchange is not new but the Corning’s Gorilla brand is the most popular these days. Corning’s Gorilla glass protects your Smartphone from breakage by some hard objects. Display is the expensive part of the mobile phone and due to this reason people are using gorilla glass to protect their device from any damage. There are several versions of the Corning’s Gorilla glass present in the market at different price range.