A Black Wallpaper Can Save Battery!
In the past we’ve shared various tips with our readers on how to get the most out of their batteries. This includes taking measures such as turning off unused connectivity options, utilizing power saving modes, and more. When it comes to optimizing your display to use less energy, one common adage is that using a black background can help you use less power. What’s the truth behind this, if any? And does it apply to all display types? Short answer: yes this is sound advice, but no, it doesn’t apply to everyone. The reason why using black backgrounds isn’t a universally good idea is that there are two primary types of display technology found in most smartphones out there: Liquid Crystal Display (LCD), and Active Matrix Organic Light Emitting Diode (AMOLED), and these two standards handle colour very differently.
While AMOLED is the latest and greatest display technology (aside from plastic OLED) LCD is the most common and well established modern display technology due to cost and age. The more black you display when utilizing an AMOLED panel, the more power savings you get. In general, displays work by emitting varying degrees of light through a pixel. Each pixel is made up of sub pixels that filter light through one of the three primary colours: red, green and blue (some manufacturers have more than three sub pixels). The amount of light that passes through these shaders determines the colour of light emitted from each pixel. Unlike LCD panels, which require a backlight, or light emitting diode (LED), in order to pass light through each pixel, the pixels that make up AMOLED panels are their own source of light. Essentially, when a pixel is displaying black on an AMOLED panel it is entirely off. To emit colour, or white, it must turn on and thus consumer power. This is why AMOLED panels are perfect for features like ambient display, as most of the pixels are not consuming power, unlike LCDs, where the entire LED backlight must turn on no matter how many pixels are actually being utilized.
LED-LCDs are made up of five layers: a polarizer, liquid crystal, transistors, another polarizer, and a backlight. LCDs use polarization filters and electrical current to block varying degrees of light passed through the liquid crystal layer by the LED. Light is a wave that oscillates in every direction from the LED backlight. A polarization filter only allows light that oscillates on a particular plane to pass through. A horizontal polarizer allows light that oscillates on a zero degree plane to pass through, a vertical polarizer does the same except on a 90 degree plane. Essentially two perpendicular polarization filters will block all light; if you look through two perpendicular polarized sunglasses all you would see is black.
Picture courtesy – gizbot.com
by techtalks @TechTalks January 27, 2016 4:56 AM UTC