QLED vs. OLED: Samsung’s TV tech and LG’s TV tech are not the same-NewsCO.com.au

February 8, 2017

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Sarah Tew/CNET

When it comes to new TV technology, the little line that turns an “O” into a “Q” makes a big difference.

Samsung, the world’s no. 1 TV maker, is set to launch its latest lineup of televisions over the next couple months. Soon to appear on the shelves at Best Buy and the search results lists at Amazon are sets bearing the acronym “QLED,” as in Samsung QLED TV.

Meanwhile, its chief rival LG, the world’s no. 2 TV maker, will continue selling sets designated “OLED.” (Philips, Panasonic and — soon — Sony are selling OLED TVs too, but all of the panels are produced by LG Display.) And if previous years are any indication, we’ll continue calling OLED-based TVs the best we’ve ever tested.

Which poses the Q: Is Samsung trying to ride the coattails of OLED’s overwhelmingly positive reputation by calling its newest TVs something nearly identical?

I queried Samsung. Company representatives didn’t answer my question directly, but replied in a statement:

“QLED stands for Quantum Dot LED TV. There are and will be many different types of quantum dot based display technologies today. Some new architectures are likely to arise in the future as well. QLED encompasses all of these variations of architecture just as the term OLED encompasses a variety of different architectures.

Using your example of OLED, OLEDs can utilize passive or active backplanes and emissive layers that are composed of white emitters with RGB or RGBW filters, or with direct RGB emitting materials and no color filters. Yet these are all classified as ‘OLED’ displays.”

Touche.

Even so, the fact remains that “QLED” looks and sounds a lot like “OLED,” and your average TV buyer doesn’t know quantum dots from passive backplanes. And this wouldn’t be the first time copycat marketing was used in the TV space. Just last year, in fact, I accused LG of aping Samsung when it called its TVs “Super UHD” — a telling echo of Samsung’s own “SUHD” name (which, incidentally, is being retired in favor of QLED).

What goes around comes around.

A QLED TV is an LCD TV with quantum dots

Marketing aside, the two technologies are very different. Here’s a quick summary.

  • OLED stands for “Organic light emitting diode.”
  • QLED stands for “Quantum dot light emitting diode.”
  • OLED is a fundamentally different technology from LCD, the major type of TV today.
  • QLED is a variation of LCD, adding a quantum dot film to the LCD “sandwich.”
  • OLED is “emissive,” meaning the pixels emit their own light.
  • QLED, like LCD, is, in its current form, “transmissive” and relies on a backlight.

In other words, as much as Samsung wants “the establishment of a category of televisions that are driven by Quantum Dot Technology,” the 2017 version of QLED is closer to regular old LCD than it is to OLED, which I (and most other experts) consider a distinctly different class of television, much like plasma was before it.

Quantum dots are microscopic molecules that, when hit by light, emit their own, differently colored light. In Samsung’s 2017 QLED TVs, the dots are contained in a film, and the light that hits them is provided by an LED backlight. That light then travels though a few other layers inside the TV, including a liquid crystal (LCD) layer, to create the picture. The light from the LED source is transmitted through the layers to the screen’s surface, which is why we say “transmissive.”

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The LCD “sandwich” is composed of multiple layers, one of which (on QLED TVs) uses quantum dots.


Josh Miller/CNET

Samsung has been using quantum dots in this way for the last two years in its SUHD TVs but says it has improved its quantum dots in 2017 to deliver better color and more brightness. There’s a new proprietary structure that “consists of a metal core, a graded ZnSeS layer and a metal jacket.”

Here’s where I mention that Samsung is actually working on a version of QLED that does use emissive technology, much like OLED and plasma. We covered it in-depth last year. The short version is that emissive QLED TVs have the potential to match the absolute black levels and “infinite” contrast ratio of OLED, with better power efficiency, better color and more. That’s pretty exciting, but it’ll be a few years before we see emissive QLED TVs available for sale. Hopefully by then they’ll think up a new acronym (EQLEDs?).

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Emissive QLED elements, like the prototypes shown here, are still a few years away from making it into TVs.


Qdvision

In the meantime, Samsung uses the same abbreviation for its 2017 QLED TVs, which use a transmissive film of quantum dots rather than quantum dots that actually emit light.

So how do QLED TVs compare to OLED TVs?

I can’t say for sure since I haven’t tested a 2017 QLED TV next to an OLED TV in my own lab yet. But for now, I can make some guesses based on what I’ve seen in previous reviews, such as Samsung’s 2016 KS8000 “SUHD” TV and LG’s 2016 B6 OLED TV.

Those suppositions are as follows:

  • I expect QLED TVs to be cheaper (for the most part) than OLED TVs.
  • One exception might be the flagship Q9 model, which could cost more at the 65-inch size.
  • QLED TVs will probably lag behind OLED models in some key picture-quality categories: I expect lighter black levels, lower image contrast, worse off-angle viewing and worse uniformity on QLED.
  • QLED picture-quality advantages over OLED may include higher light output and better color for HDR sources.

Samsung’s demos and messaging to the press and reviewers like me has focused on those potential advantages. It claims a boost in peak luminance (light output) up to 2,000 nits in highlights, double LG’s claim for its 2017 OLED TVs. Samsung also says it has improved upon one issue last year, where some models would exhibit delayed ramp-up, and relatively quick decay, of peak luminance.

As for “better color,” Samsung has run a bunch of side-by-side demos featuring its 2017 QLED TVs compared to 2016 LG OLEDs. I recently attended one at its lab in New Jersey. The demos show punchier, more dynamic colors in HDR, both with test patterns and specialized clips.

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A Samsung engineer measures color on QLED (top) and OLED (bottom) TVs. Due to off-angle and other factors, don’t take this photo to represent real-world colors.


David Katzmaier/CNET

Samsung says the reason for the difference is because new quantum dots enable superior “color volume.” The idea is to produce fully saturated, rich color no matter how bright the image gets. In Samsung’s demos, colors on the OLED TVs wash out and become less vibrant and realistic in very bright areas, while QLED TVs maintain that saturation.

The makers of the CalMan software I use to evaluate and calibrate televisions are developing a way to measure color volume, which will debut later this year. It also featured into Samsung’s demos, and again showed an advantage for QLED compared to OLED.

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Coming soon is a feature in CalMan that allows measurement of color volume.


David Katzmaier/CNET

All of these demos and measurements might seem impressive, but it’s important to remember that they were performed in a test environment under Samsung’s control, not by an independent party (yet).

Even more important is that both the light output and color volume advantages only apply to HDR (high dynamic range) material. The vast majority of stuff you’ll watch on any TV is still in standard dynamic range (SDR), and I don’t expect QLED to beat OLED with that content. Even with HDR, OLED’s contrast advantage might trump QLED’s strengths, especially since all QLED TVs will use edge-lit local dimming, which historically performs worse than full-array.

All of these questions and more will be settled when I can review Samsung’s latest crop of TVs in my lab, something the company says will happen soon.

In the meantime, mind your Os and Qs.

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