LED vs LCD?

02/03/16
Aubrey Wright

At recent AV trade events there has been a good deal of discussion about the relative merits of LED versus LCD screens. Unfortunately, for such an important component, the debate is engulfed in confusion. This is in part because technically speaking, an LED screen is also an LCD, as the screen on both is a liquid crystal display. An LCD display has two layers of glass that are polarized and joined together, the liquid crystals then pass or block the light to display the image.

The crystals themselves do not produce any light as the light comes from a series of lamps at the back of the screen. On an LCD screen, the lamps at the back of the screen are fluorescent, while on an LED screen the lights at the back of the screen are Light Emitting Diodes (confusingly also abbreviated to LED).

Its all about Back Lighting
There are two LED methods used to provide the back lighting to the screen: edge lighting (with or without local dimming) and full array lighting (with or without local dimming). Most existing LED TVs fall in the edge-lit without local dimming category, with the LEDs placed only along the edge of the LCD panel, using “light guides” to illuminate the centre and other areas of the screen. 

Since its original introduction, manufacturers have come up with a better version: “edge lit with local dimming.” This version results in better picture quality, with the black levels becoming darker, providing a greater realism. That said, manufacturers have also varied the quality of dimming where the image quality is paramount and cost is not such an issue.

Picture quality
If you want the best in picture quality on a LED screen or TV, technically it will have to be one that has full-array back lighting with local dimming. The individual zones of LEDs can be dimmed or brightened independently, making it more flexible and suitable for the ambient lighting in any location.

LED screens generally have better black levels and contrasts than their LCD counterparts. Colour accuracy is also slightly better on LEDs. 

Viewing angle is more or less the same on both as this will depend on the glass panel used by the manufacturer. A thicker and higher quality glass panel is expected to provide a better viewing angle. 

There are other issues to weigh such as brightness and contrast ratios. Selecting the right mix of qualities will depend on local siting and what effect is required. Choosing a company like Handy AV with extensive experience of both designing and installing screens can make all the difference to the screen choice and the impact of the show.

Energy efficiency
Where power consumption or cool running is a major concern, then what you need are energy efficient screens. LEDs get the vote here, using less light to display its pictures. These are designed to produce better quality pictures while also using less power than LCD models.

Size and price
In terms of size, LED TVs are slimmer. LED lights can be installed in smaller places, allowing manufacturers to trim out some unnecessary weight. The lighter LED screens are also better suited to video walls and multiscreen displays because of the greater flexibility at installation. Screen life is similar in both screens and is actually conditioned by other factors such as how often the installation is powered up. One reason the debate continues to rage is that manufacturers continue to innovate and drive down prices.  There are also economic efficiencies here. LED screen factories supply everything from small mobile sets up to very large screens, whereas LCD screens are a more uniform product.

Conclusion
Like everything in the AV world, technology and prices are forever changing. Working with a full service provider like Handy AV that both installs and maintain systems, as well as imports bareback screens for sale, will give you the best advice on what to choose.