If you're old enough to remember CRT televisions, you probably remember the phenomenon of screen burn where an image would be permanently etched in to the display. This problem largely disappeared with the invention of LCD technology, but has recently become a problem once more with the increased adoption of OLED displays.
Screen burn is a phrase used to describe a permanent discolouration of a display. In mobile phones this usually takes the form of text or more commonly, icons and navigation buttons. The display will still work as it should, but in certain conditions you will be able to see obvious ghost images that persist even when the icon or offending element is not present on the screen.
Screen burn is a widely recognised phenomenon, and manufacturers like Google even have support pages advising how to protect your screen from these effects.
While LCD screens are generally not affected by screen burn, OLED screens are very susceptible to it. OLED screens have been becoming more popular over the years as they offer many benefits over LCD screens; better contrast, greater battery life, thinner displays, deeper blacks and greater viewing angles. Unfortunately, these improvements come with some trade-offs, one of which is screen burn.
Screen burn is the result of the natural life cycle of the components of your phone's display. As these components age their ability to maintain their original brightness diminishes, causing the colour of the screen to gradually shift over time. To understand this you need to know a little about how screens work. Screens are composed of pixels. Thousands of these make up the display and their brightness and colour determine what image is being displayed on the screen at any given time. Each pixel is in turn made up of three sub-pixels, one red, one green and one blue.
The the more hours a given pixel or sub-pixel is on for, the more it will age and the dimmer it will become. Some areas of the display regularly show the same thing, such navigation icons, app icons and the notification bar. As a result of persistently showing the same colour, these pixels age differently to the rest of the screen, causing a colour variation in that area that matches what was being displayed. For example, if you have a red icon in one area of the screen, the more the screen is used with the icon visible, the more those red sub-pixels will age compared to the red pixels around them that are not constantly lit. This will cause a shift in that area where the screen becomes more green and blue as the red sub-pixels dim.
Unfortunately if your screen is already ?burned? there is no way to undo the damage. You can however take steps to prevent it from happening in the first instance, or at least increase the amount of time before it becomes noticeable.
Screen burn is something to consider when you are buying refurbished devices or selling a used phone. As certain devices are quite prone to screen burn, such as Sumsung devices, you should check for any issues. There are apps available in most app stores to illuminate your screen plain white so you can check for any burned in icons. Most refurbishers and recyclers will need to replace a burned in screen before they can resell the device, and may reduce the market value of your phone.
