Bright, brighter, brightest? Why a display backlight system is more than meets the eye

Let there be light!

If only it was that simple in the world of display backlight systems.

To begin with, the human eye doesn’t perceive light in a linear way. So, if you’re looking to achieve a super-bright result, your display will need a huge amount of energy – more than double, in fact. For energy critical devices, this often means compromising brightness for battery life and the decision is taken to run with a low brightness display.

Shooting more light through a TFT cell will wash the colors out, so even the cell itself needs to be modified to convert a dim display to a sun-defeating lantern that is still capable of showing saturated colors. High-performance LEDs can also help to reduce heat, yet additional passive cooling techniques are still often required.

Proper backlighting is complex even in advanced edge or back lit arrangements, where LEDs are arranged in a line (edge lit) or array (back lit). They form miniature points of super bright light and subsequently take on the characteristic of a spotlight. Therefore, a system of light shaping elements needs to convert the multiple tiny dots into a uniform area of light.

The end goal is high brightness, low heat dissipation and the correct white point. Which, in and of itself, is not straightforward. A proper mix of wavelengths is required to ensure a wide color space for the emitted picture. Because what is considered ‘white’ in one context may not necessarily be the same as ‘white’ in another. And in a final layer of requirements: the whole backlight system must be as thin as possible.

All these considerations for just one function?

When we describe it this way, it sounds impossible to achieve, but we do ­–again and again, millions of times with best results. So, we know and understand just how important each of these elements are for application designers. The selection of proper display brightness, and in some cases even the correct customization of a display backlight is mission critical and may well decide between failure and success of a final product introduction.

Our experts are on hand to guide you in the creation of display or touch solutions that meet your requirements. Find out how Avnet Embedded can propel your product innovation and get in touch today.


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