How Backlights Work in LCDs
Whether it's a TV, computer monitor, human machine interface (HMI) or any other liquid-crystal display (LCD), a backlight must be used to illuminate the liquid crystals. Without a backlight, you wouldn't be able to see images on the display device. Unless you're familiar with backlighting technology, though, you might be wondering how it works exactly.
Overview of LCD Backlights
The purpose of backlights in an LCD is to illuminate the liquid crystals. In the past, backlights weren't always needed with display device. Cathode ray tube (CRT) display devices, for example, create their own illuminate, thereby eliminating the need for backlights. Light-emitting diode (LED) displays also produce their own lighting using an array of many small LEDs. But LCDs don't have the ability to produce their own lighting, so manufacturers must design them with a separate, built-in light source. Known as a backlight, it's essential to an LCD's operation. It projects light from behind the liquid crystals, illuminating the display so that you can see colored images depicted on the screen.
Backlights May illuminate From the Side As Well
Based on the name "backlight," you may assume that they always illuminate liquid crystals from the rear. While true for most LCDs, though, this isn't always the case. Some LCDs are designed with backlights on the side of the liquid crystals. It's an alternative configuration that allows for ample illumination while conserving space in the process. Configuring an LCD with backlights on the side creates a lower profile, thus allowing for slimmer LCDs. With that said, some LCDs are configured with lights on the front. These aren't technically backlights, however. Rather, they are referred to as "frontlights.
