For the top layer of any iPhone
During its manufacture, the glass is toughened by ion exchange. The material is immersed in a molten alkaline potassium salt at a temperature of approximately 400 °C, wherein smaller sodium ions in the glass are replaced by larger potassium ions from the salt bath. The larger ions occupy more volume and thereby create a surface layer of high residual compressive stress at the surface, giving the glass surface increased strength, ability to contain flaws, and overall crack-resistance, making it resistant to damage from everyday use.
Just keep in mind that as resistant as it can be, it is still glass.
The glass is a part of your iPhone’s screen not because smartphone manufacturers want to make phones particularly frail or weak, but because it is an important part of how the screen reacts to touch.
Touchscreens on all cell phones use a technology called “capacitive sensing”. This uses a layer of glass as an insulator (which means it does not transmit electricity), coated with a conductor (which can transmit electricity).
The conductive layer is usually a combination of metals called “indium tin oxide” (ITO). These metals are transparent, so you can see what is being shown on the display underneath.
Because the human body is also an electrical conductor, when your fingers make contact with the touchscreen, the conductive coating registers this as a change in the iPhone screen’s electric field. This is how your iPhone knows where you are tapping or dragging on the screen itself, even if you use multiple fingers at the same time.
Touchscreens use a series of steps to process the information entered by touching your iPhone’s screen:
All of this happens almost instantly. In fact, you probably will never notice a delay between touching the screen and the action happening. Not only can your iPhone do all of that in a nanosecond, but it can also calculate multiple touches at once, like
You might think that touchscreens having a “multi-touch” capability is new technology. And it is pretty new, relatively speaking. In 1982, a group from the University of Toronto created a screen made of a camera behind a pane of glass which could register any human input. This awkward and hard to use interface was improved by U of T in 1985 with the first version of the modern touchscreens we know and love today.
Apple claimed they invented the multi-touch technology in 2007 with the release of the first iPhone, but both the phrase “multi-touch” and the actual function itself existed well before the rise of the iPhone. However, they are not being completely dishonest, as Apple holds several patents for the mobile device version of the technology.
Apple prides itself on
The gestures accepted by the iPhone touchscreen are also very natural-feeling. Using multi-touch gestures to do a variety of movements, such as scrolling the screen, or expanding or shrinking the screen’s contents are often naturally understood by the user.
Most smartphones use LCD technology for screens because it is thin and relatively cheap when compared to its lifespan.
The display of your iPhone is a high definition “liquid crystal display” or LCD for short. Liquid crystals might sound like something impossible, because how can something be both a liquid and a solid at the same time? But because these crystals can do both at the same time, the result is a screen which can display millions of different colours with no visible delay.
These liquid crystals are laid out in between two pieces of polarized glass, underneath the touchscreen. This layer is then powered by thin wires laid out in a grid underneath the crystals.
The crystals act like shutters, opening and closing above a colour filter composed of tiny red, green, and blue “sub-pixels.” These sub-pixels are invisible to the naked
The crystal component of the LCD is only half of the equation. The liquid crystal layer doesn’t project any light on its own, so your iPhone needs a layer of lighting (usually small, low-powered
Starting with the iPhone 4, Apple calls the new screen technology a “Retina HD” display:
“Rather than using traditional methods to create the higher-resolution Retina HD display, we developed an advanced process of
Their new technology promises a few interesting perks, like increased visibility in direct sunlight or with sunglasses on. Another added functionality of the Retina HD display in the latest iPhones is a wider viewing angle. The “viewing angle” is the largest angle that the display can still be acceptably used at.
Apple says the screens can now be comfortably viewed from almost any angle. This is possible because of the screen’s higher contrast and extra pixels.