The Direct LED-Lit LCD TV Option
First introduced (but quickly forgotten, oddly) by Samsung, LCD TVs with direct LED lighting illuminate using LED light clusters ranged behind the screen rather than a single CCFL bulb.
The initial direct LED-lit LCD TVs were the first to convince us that LCD really could take on plasma as a premium quality, film-friendly technology.
Fortunately, after a couple of years of other pretty cost ineffective direct LED options, direct LED screens are now becoming both more common and more affordable.
The basic idea behind using direct LED lighting is blindingly simple. First, LED lights are both more economical and more flexible to run than CCFL lights, with their ability to run stably at lower illumination levels than CCFLs being particularly handy. Second, having an array of lights rather than the single CCFL light source opens up the possibility of controlling each of the separate LED 'clusters' independently – AKA local dimming.
Much Improved Contrast
As noted a moment ago, LED lights can be dimmed to lower levels than CCFLs. This means practically all direct LED TVs produce markedly superior black level performances to CCFL LCD TVs. Indeed, the best direct LED TVs can even challenge many plasma screens for sheer black colour purity.
Direct LEDs that make use of local dimming can be particularly effective when it comes to contrast, thanks to the potential for one LED cluster to be firing at full power right alongside another cluster that’s producing practically no light at all.
Rich, Dynamic Colours
The properties of LED lighting generally seem to help produce a wider colour spectrum than other flat TV technologies. This is especially true with premium direct LED TVs like the Sharp XS1E and Sony X4500 models, which use (now pretty much defunct) RGB dimming technology rather than the more common white dimming.
No Screen Burn or Fizzing
As with CCFL LCD TVs, direct LED LCD TVs don’t suffer with image retention or fizzing noise like some plasmas do.
High Brightness Levels
Having an array of LED lights driving the picture can really boost brightness levels, to the point where some direct LED images look positively luminous.
LED lights are easier to drive than CCFLs, with the result that direct LED TVs typically use markedly less power than non-LED flat TV formats.
Missing Shadow Detail
While direct LED TVs that use local dimming can produce the richest contrast, they can also cause details in dark areas of the picture to go AWOL. This is because the number of LED clusters is small versus the number of pixels in the picture. Even the best direct LED sets currently have around 250 LED light sources, versus 1,920 x 1,080 pixels. So it follows that if you are turning some of these LED clusters off or lowering them to try and produce good black colours, then individual bits of detail in those dark areas could go missing. It’s common, for instance, for direct LED TVs to show less stars during outer space shots than our other types of flat TV.
Again because of the relative paucity of LED light sources versus the number of pixels in the picture, it’s occasionally possible to see subtle haloes or clouds of light around the edges of bright objects when they appear against very dark backgrounds.
As with other forms of LCD TV, direct LED ones lose colour and contrast if viewed from an angle of more than 40 degrees or so. The haloing phenomenon described in the point above also becomes much more pronounced during off axis viewing.
While often handling motion better than CCFL LCD TVs, many direct LED LCD TVs still lack motion resolution versus the best plasmas.
Direct LED TVs – or at least the ones with local dimming – tend to be expensive.