4 Common Types of LED Backlighting for LCDs

May 26, 2021

Light-emitting diode (LEDs) are often used to illuminate the pixels within liquid-crystal displays (LCDs). All LCDs contain a layer of liquid pixels. With the exception of organic light-emitting displays (OLEDs), these pixels aren’t capable of illuminating themselves. Rather, they require illumination from an external system known as backlighting. Most LCDs use one of four types of LED backlighting as described below.

#1) Edge-Lit

The most common type of LED backlighting for LCDs is edge-lit. Edge-lit backlighting refers to the use of LEDs around the perimeter of an LCD’s screen. Edge-lit LCDs still feature the same liquid pixels as other LCDs. For the backlighting, though, they feature a perimeter or rim of many small LEDs. These LEDs will illimunate the LCD’s pixels form the sides, thereby producing visible images.

#2) Direct-Lit

Some LCDs feature direct-lit backlighting. Direct-lit backlighting is a type of LED-based backlighting that involves the use of LEDs in a grid pattern directly behind the pixel layer. It’s not the same as edge-lit backlighting. With edge-lit backlighting, the LEDs are placed around the perimeter or rim of the LCD. With direct-lit backlighting, the LEDs are placed behind the pixel layer. They are arranged in columns of rows to form a grid. During operation, the grid of LEDs will illuminate the pixel layer from behind.

#3) Local Dimming

Another common type of LED backlighting for LCDs is local dimming. With local dimming, clusters of multiple LEDs are individually controlled. Most local dimming LCDs feature a similar arrangement of LEDs as direct-lit LCDs. In other words, they have a grid of LEDs rather than a perimeter of LEDs. The difference is that local dimming LCDs can control groups or clusters of LEDs separately than the other LEDs.

#4) Full Array Local Dimming

Finally, there’s full array local dimming backlighting. This alternative backlighting technology is similar to direct lit backlighting. Both direct lit backlighting and full array local dimming backlighting feature a grid of LEDs. The same applies to local dimming as well. What is full array local dimming exactly? It’s a backlighting technology in which each LED is individually controlled.

With direct-lit backlighting, all of the LEDs are controlled at once. With local dimming backlighting, clusters of LEDs can be controlled individually. And with full array dimming backlighting, each LED can be controlled individually. Fully array local dimming LCDs cost more than those using a different type of backlighting. Nonetheless, they provide excellent brightness and contrast that’s superior to their counterparts.

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