tech&trends Mobile Displays: Battle of As screen size is getting larger, it makes the display more vulnerable to damage/scratches through accidental drops. But with names like Gorilla , Sapphire, , etc you don’t need to worry anymore – Anuj Sharma

he smartphone screen is the one of important components of the device as this is where you will spend most of the time interacting with Tit. We all stick screen guards to protect it from those scratches or hairline breaks and also pack them in cases so that it does not shatter on fall. So the best way to avoid the agony is to make the screen completely scratch resistant. We all know about and how it pro- tects the screen. Let’s now take a detailed look at what it as well others have to offer.

Corning Gorilla Glass Gorilla Glass is an alkali-aluminosilicate sheet toughened glass developed and manufactured by Corning. The glass improved mechanical durability of the glass to in-field dam- combines thinness, lightness and damage-resistance age such as through drops. properties and is widely used as a cover glass on most , tablets, screens etc. Fusion and Sapphire Glass Ion-Exchange processes are employed in making the glass. Sapphire is not new and it’s not just a gemstone. It is a In the fusion process raw materials (silicon dioxide) are transparent crystal that happens to take on some attractive blended into a glass composition, which is melted and hues yellow, purple, orange, green or red when it forms conditioned. The resulting glass is aluminosilicate that naturally. However pure sapphire is hard to find thus combines aluminum, silicon and oxygen. The molten synthetic sapphire has been widely used in wristwatch glass is fed into a trough called an isopipe. It then rejoins, crystals, windows, camera lenses, etc. Synthetic sapphire or fuses, at the bottom, where it is drawn down to form is manufactured by applying high heat and pressure to a continuous thin sheet of flat glass. Ion exchange is a aluminum oxide powder (sapphire is, after all, just a chemical strengthening process where large ions are compound of aluminum and oxygen). It is heat-treated to stuffed into the glass surface. The glass is placed in a hot eliminate its internal stresses which can cause weakness bath of molten salt at a temperature of approximately and later processed into sheets to form what is known as 400 degrees. Smaller sodium ions leave the glass, and sapphire glass. And that’s what ends up on your phone as a larger potassium ions replace them. These large ions are cover glass. pressed together producing a layer of compressive stress It is 4 times tougher than glass and is also considered as on the surface of the glass. This allows the potassium ions hardest material after moissanite and diamond, projecting to diffuse far into the surface, creating high compressive a value of 9 on Mohs scale that measures mineral hard- stress deep into the glass. This layer of compression creates ness. The key benefits of sapphire is that it is highly trans- the surface that is more resistant to damage. By 2010, Gorilla Glass 1 was used in approximately 20 percent of mobile handsets worldwide. The second generation, called Gorilla Glass 2, was introduced in 2012 and is 20 percent thinner than the original Gorilla Glass. Gorilla Glass 3 is up to three times more scratch-resistant than the previous version of the product, demonstrating an enhanced ability to resist deep scratches that gener- ally weaken glass. Recently Corning introduced GG4 in the consumer electronics market. Gorilla Glass 4 provides at least two times improved damage resistance resulting in

22 PCQuest February 2015 pcquest.com twitter.com/pcquest facebook.com/pcquest linkd.in/pcquest [email protected] How different glasses compare Single Crystal Glass Physical Property Units Sapphire Corning Gorilla Glass DragonTrail Glass Soda Lime Glass Density g/cm3 3.97 2.42 2.48 2.5 Young’s Elastic of Modulus GPa 345 71.5 74 73 Shear Modulus GPa 145 29.6 30 30 Fracture Toughness Mpa√m 2.3 0.68 1.2-1.8 0.7-0.8 Knoop Hardness GPa 18.6 6.17 6.95 6.03 Vickers Hardness kg/mm2 2200 649 673 580 Di-electric Constant k 9.39 7.23 7.3 7.75 Refractive Index ɳ 1.76 1.51 1.51 1.52 parent to wavelengths and highly resistant to scratching expensive as it involves large furnaces and diamond to and abrasion. Apple is now implementing this glass display make it ready for the purpose. And after that cumbersome in touch ID of the iPhone 5s, iPhone 6, and iPad mini 3 and process, the output is a material which is 67 per cent the display of the Apple Watch. Also, sapphire covers are heavier than Gorilla Glass and even less transparent. used for the rear camera in iPhone 5 and 6, and every iPod Sapphire is harder not stronger and is less likely to get Touch (5th generation) or newer. scratched. On the other hand, Gorilla Glass may survive a fall more often than Sapphire. Gorilla Glass transmits more Dragontrail Glass light than Sapphire thus implementing Sapphire means Dragontrail, manufactured by Asahi Glass Co., is an dimmer devices. alkali- aluminosilicate sheet glass which has properties like thinness, lightness and damage-resistance, similar to the Gorilla Glass. The glass is produced using High Ion Exchange process which is then chemically strenghtened to achieve scratch, break/impact, and shock resistance. The resulting glass is strong, lightweight and flexible. The material’s primary properties are its strength, allowing thin glass without fragility, its high scratch resistance and its hardness making it and ideal solution for cover glass and touch screen applications. Dragontrail was launched in 2011 and is used by the Oplus XonPhone 5, series, Xiaomi MI2 and Redmi, , Xolo Q1000 and Q1010i, XOLO Win Q900S, etc.

Soda Lime Glass Soda-lime glass is relatively inexpensive, chemically stable, reasonably hard, and is capable of being re-softened and re-melted numerous times, thus it is ideal for glass recy- cling also. It is prepared by melting the raw materials, such Gorilla Glass vs Dragontrail as sodium carbonate (soda), lime, dolomite, silicon dioxide Both these glasses are very hard, tough and scratch (silica), aluminium oxide (alumina), and small quantities of resistant. It should be noted that these glasses are scratch fining agents (e.g., sodium sulfate, sodium chloride) in a resistant and not scratch proof, which indicates an object glass furnace at temperatures locally up to 1675 °C. resistance to something upto a particular limit or potential. On the other hand being scratch proof means that they Gorilla Glass vs Sapphire have almost unlimited level of resistance and cannot be Sapphire is much harder to scratch than Corning’s industry penetrated by a particular thing or object. Thus it indicates leading Gorilla Glass or Dragontrail Glass. From the that both these glasses can guard themselves from manufacturer’s point the hurdle in implementing Sapphire scratches or damage to a certain vantage point, but they on displays is its manufacturing cost. It’s about 10 times can be scratched and can be damaged if you drop them more expensive and 1.6 times heavier than glass. Also from a great height or apply too much pressure with a very it requires more energy to generate a Sapphire crystal pointed object. So if you are in for market looking for a than it does to generate glass. Producing Sapphire of the smartphone equipped with any of these glasses you should same quantity as Gorilla Glass is nearly three times more not worry about much. pcquest.com twitter.com/pcquest facebook.com/pcquest linkd.in/pcquest [email protected] February 2015 PCQuest 23