Stephan Jukic – April 3, 2017
For novices to the world of 4K UHD TV technology, a lot of terms like OLED, LCD, LED and now even QLED pop up all over the place to confuse the buyer and leave a bit of doubt about what the hell kind of TV is simply best for you and your budget? In addition to these bits of display technology terminology, you’ll also hear about stuff like IPS display and VA display, possibly wondering what the differences between those two mean as well.
Well, while we’ve explained many of these different technologies throughout the pages and posts of 4K.com, we think it’s maybe worth giving a bit of robust clarification in a single concise post where OLED, QLED, LCD/LED and their details are all laid out clearly.
Let’s start with the most widely known, affordable and common type of TV panel, LCD/LED. This is also where VA and IPS panel subtypes come into the picture. These two display panel technologies will shortly be covered more robustly in another post.
LCD/LED 4K TV
A Samsung KS8500 LCD HDR 4K TV from 2016
The oldest and most traditional TV display type among the three television technologies discussed here is LED/LCD. The vast majority of 4K TVs sold today are LED/LCD models and even QLED TVs (for now) follow this basic design type, as we’ll explain further below in the QLED section.
In basic terms, LED/LCD display technology works by delivering light from LED backlight arrays of different types to an LCD panel in which RGB (Red Green Blue) pixels are integrated. The light passing through the pixels produces brightness and color in an LCD/LED TV while technologies such as local dimming (by which select areas of the LED backlight array can be shut off, check out our guide on this here) and light blocking filters in the pixels themselves create dark areas on a TV display. Not all 4K TVs have local dimming capacity and even the majority which do only offer the technology to a very limited, imprecise degree. Thus, the black levels in LCD/LED TVs are generally far from perfect, even though they have gotten much better than before in newer 4K TV models of this kind.
Some high-end LCD TVs offer full-array LED backlighting in which their backlight LEDs cover the entire rear of the screen, while other TVs only offer LEDs along the display edges. Furthermore, many newer, premium LCD TVs offer special quantum dot color filters in their LCD panels for delivery of wide color gamut. This in fact makes them similar to QLED TVs as they stand today.
Generally, LCD/LED TVs are among the most affordable 4K HDR or SDR TV types sold on today’s market due to the high standardization and establishment of their display technology. This however doesn’t mean that they lack for high quality picture performance, as we’ll shortly cover.
QLED 4K TV
QLED technology is two different things right now. On the one hand, it’s the potential future of 4K TV display due to certain developmental elements which promise to almost completely rework how 4K TV displays work. On the other hand, the QLED display type that we see actually on the market in the 4K TVs (from Samsung only for now) of 2017 is almost identical to LCD/LED TV display but with some moderate modifications for increased color performance and viewing angles. In other words, QLED, as it’s available now, mostly consists of a marketing name attached to what are in fact LCD/LED TVs of the same kind that has been available for a while.
One of Samsung’s 2017 QLED 4K LCD TV models, the Q7F
The one main difference between today’s QLED TVs from Samsung and that brand’s or any other company’s LCD/LED TVs is that the new QLED models offer new, specialized metallic quantum dot nano-particle filters over their LEDs for purer, more accurate and more saturated colors.
Unlike many marketing names for 4K TVs today, Samsung’s QLED label does actually have some serious substance to it, and while the brand’s QLED TVs are in many ways just like their other premium LCD/LED TV cousins, they offer a genuinely superior level of color performance, even if the extra wide color gamut percentage is fairly small.
It’s also worth noting that QLED TV displays come with the same LED backlighting arrays and comparable black level/brightness specs to their non-QLED counterparts. Samsung’s Q7F, Q8 and Q9F QLED TVs, for example, are all edge-lit, just like most of Sony’s, LG’s or Samsung’s previous LCD 4K TVs.
A Special note on the future of QLED:
The above describes QLED technology as it stands today. However, there are developments taking place right now for a much more advanced QLED display technology by which, in very basic terms, the pixels of a 4K TV themselves will be made up of light-reacting nanoparticles that not only glow when electrical is run through them but also provide their own specific RGB color emissions. This new development would make future QLED TVs very similar to OLED TVs in their fundamental design but even better performers than OLED due to much more direct color creation inside the pixels themselves.
Quantum Materials for current and future QLED display technology
OLED 4K TV
OLED TV display technology, as we explain here in our OLED vs. LCD Guide, is fundamentally different from all existing LCD/LED TV designs and in most ways, a far superior performer at nearly every picture quality spec there is. OLED TVs are today generally the most expensive and best performing types of 4K HDR or SDR TVs being sold.
The way in which OLED works is largely responsible for such high performance metrics: Unlike LCD/LED TVs, OLED televisions have no backlight at all. Instead, each pixel on an OLED panel contains a tiny organic light emitting diode that lights up or completely turns off into full darkness depending on whether current is being run through it or not. As a result, OLED 4K TVs are capable of delivering perfect local dimming right down to the single-pixel level of precision (in a 4K TV this effectively means 8.29 million local dimming zones ) and due to the total black they can create by deactivating pixels, OLED TVs also deliver perfect, infinite contrast.
Color in OLED TVs is delivered by blue and yellow OLED crystals whose light then passes through red or green filters in different configurations over each pixel to create all the display colors and white that you see on the screen. OLED TVs are known to be less capable of high peak brightness than their best LCD/LED counterparts but this is now changing drastically and in any case, due to the perfect black levels of OLED, even a dimmer display panel creates far better perceived contrast.
Black & Contrast Performance between LED/LCD, QLED, OLED
Moving on to the performance differences between all three panel types, we start off with the single most important pair of specs for 4K TV display quality: contrast ratio and black levels. In LCD TVs these can vary enormously depending on manufacturer, panel type (IPS vs. VA mainly) and the presence of local dimming technology. In OLED TVs, black levels are almost universally perfect and contrast ratios are almost universally infinite. In today’s QLED TVs, the same applies as for LCD TVs but with less variation since all current QLED TV models come with VA display panel technology, which is known to deliver much better black levels than IPS panel display in 4K TVs.
contrast differences between VA Panel LCD TV display and its IPS counterpart
In basic terms, if you want perfect contrast, perfect black levels and pixel-perfect local dimming, an OLED TV cannot at all be beaten by either LCD or QLED TVs of any kind. If however you can’t afford the typically steeper prices of some OLED TVs, then a 4K LCD TV with VA panel display will normally deliver contrast ratios of 4000:1 or higher and the best LCD 4K HDR TVs with VA panels today normally deliver excellent black levels of 0.016 to 0.020 nits. All QLED TVs are VA models so all of them deliver this kind of contrast ratio and black level or better. Local dimming in premium 4K LCD TVs can allow for certain darker areas of the TV display to deliver extremely deep black levels but this can’t be done with anything close to the precision with which it’s possible in OLED displays, for which a single pixel can be made to emit no light whatsoever even if it’s surrounded by lit pixels.
IPS 4K LCD TVs, especially those without local dimming, typically offer the worst black levels and contrast ratios of all models, with contrast commonly topping out at 1100:1 and black levels hovering at 0.080 nits in even the very best IPS 4K HDR TVs sold today.
Brightness between LED, QLED, OLED
Brightness levels aren’t nearly as important as black levels in any 4K TV and even in HDR models, mid-range peak brightness can be compensated for by deeper blacks which increase the perception of brighter highlights in an on-screen image. Nonetheless, the major race today among manufacturers of virtually all premium 4KTVs of all types is for panels that reach previously unheard of levels of peak luminosity. The winners in this area are without a doubt LCD/LED TVs and QLED LCD TV models. The best televisions with both technologies can reach between 1400 and in some cases even 2000 nits of peak brightness. This is a lot and it comes much closer to simulating reality than anything yet seen in home television technology. For the majority of 4K LCD/LED TVs, peak brightness rarely exceeds 500 to 700 nits and many mid-range LCD TV models only manage about 400 to 500 nits even with HDR contrast enhancement technology built into them.
Contrast and brightness differences between OLED and LCD 4K HDR TVS (OLED on the left middle)
QLED TVs in particular, because they are all premium models, offer particularly high brightness levels of 1000 nits or more, with the top-shelf Samsung Q9F QLED TV model managing almost 2000 nits of peak brightness in a 10% area of its display. This is impressive indeed and only matched by Sony’s best LCD 4K TV, the Z9D, whose backlight array can manage as many as 2000 nits as well.
OLED TVs are a bit trickier to pin down on brightness performance. On the one hand, OLED has traditionally been associated with lower levels of peak brightness due to developmental limitations in the organic light emitting diodes which generate brightness in these TVs. However,, on the other hand, because OLED TVs create perfect blacks and infinite contrast where needed, their bright highlights stand out far more impressively than they do in almost any LCD or QLED LCD TV. Furthermore, while some of LG’s earliest OLED TVs could barely deliver peak brightness levels of 300 nits, the newest HDR models from 2017, such as the Signature W-7 OED TV, can offer peak brightness at nearly 1000 nits, enough to put the vast majority of LCD TVs to shame. In absolute terms however, the very best and brightest LCD and QLED TVs still massively beat the very best OLED TVs at how high their peak brightness can go.
Peak brightness in a 4K TV screen over a 2% window.
Color Performance between LED/LCD, QLED, OLED
Color performance between LCD TVs, QLED LCD TVs and OLED TVs is in many ways similar. Furthermore, now in the age of HDR wide color gamut TV technology, all premium 4K TVs of LCD or OLED design come with wide color gamut of over 90% DCI-P3 color space coverage for more saturated, vibrant and more realistic color performance. In other words, you’ll get awesome colors, and especially for HDR-mastered content from any of the above display types if you’re buying a full HDR TV (as all QLED TVs and most OLED TVs are in particular).
However, what we’ve noticed from our reviews of OLED, conventional LCD and now QLED TVs is that QLED technology from Samsung for quantum dot nano-particles does indeed deliver measurably higher levels of color performance over those of either OLED TVs or other premium HDR TVs we’ve looked at so far. OLED TVs on the other hand do deliver particularly realistic colors and their superb black levels particularly enhance the perception of vibrant color delivery, so they’re definitely, slightly superior to even high quality conventional LCD TVs we’ve looked at.
Motion Blur between LED/LCD, QLED, OLED
Moving pictures in a 4K TV can to some extent blur as the pixels which they shift through change from one color to another. The response time of these pixels, or the speed at which they change colors to represent motion in a picture is what most affects whether a TV smoothly handles fast picture motion or does so in a blurry way that can even be painful to watch. This applies especially to action scenes and lower response times mean less motion blur than higher response times.
Motion blur
LCD TV response times can vary enormously, with some low quality 4K TV models creating major blur during fast moving action and many premium HDR 4K LCD TV models delivering excellent motion blur control. QLED LCD TVs in particular are showing themselves to be great at handling color changes in their pixels very quickly with a particularly low response time by LCD TV standards.
However, OLED is unbeatable at motion blur handling. Due to the nature of their light and color emitting organic diodes, the pixels in these TVs can change colors virtually instantly with an extremely low response time.
What Kind of TV Display Should I Go For?
The bottom line is this. If you can afford it, go for an OLED TV due to their performance superiority across the board. However, if you want the best possible brightness and color performance so far, the best of Samsung’s new QLED TVs are even better performers in these two key areas. As for the majority of 4K LCD TVs and particularly those with HDR, it will depend a lot on specific model characteristics but in general, most of today’s 4K TVs perform wonderfully for most content as far as the average viewer’s needs are concerned. If you’re on a tight budget, many mid-range LCD TV 4K models from Sony, Samsung, LG and particularly Vizio will still deliver excellent display quality for most TV, disc, media player or streaming content since most of it isn’t HDR-formatted anyhow.
Story by 4k.com
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