Tuesday 29 June 2021

What is OLED? Black levels, burn-in, and contrast ratios explained

What does OLED mean? Many of us have heard this term before, but it’s not always easy to define in a sea of other tech-related acronyms. 

Put simply, OLED is a type of advanced TV panel technology. Next time you visit an electronics retailer – whether that’s in real-life or online – take a look around. You’ll find the vast majority of new, high-end TVs that you can buy are OLED TVs.

That means if you’re in the market for a new television, you should get your head around what OLED is – even if it’s inevitably going to be in your next big TV purchase, it’s good to know why you need it. 

For starters, OLED stands for ‘Organic Light Emitting Diode’. This describes the type of panel used within an OLED TV to display all the things you see: colors, light and images.

It’s this type of panel that makes OLED different to other kinds of TV technologies, including CRT (cathode ray tube), LED (light-emitting diode), LCD (liquid crystal display), or QLED (quantum dot).

As a general rule, don’t feel like you need to learn what every tech term means – that would be exhausting. But if you’re looking to buy a new TV, or you’re keen to understand the latest news about today’s best TVs, we think it’s worth learning more about OLED.

Many of the latest and greatest televisions you can buy today have OLED panels built into them – as do high-end smartphones, including the iPhone 11 Pro. These days, it’s only Samsung’s QLED panels that offer a rival to this type of tech. (You might have heard of MicroLED, but that still has a way to go before it catches up.)

Although you’ll find OLED in many places these days, that doesn’t mean it isn’t worth getting excited about what this TV panel tech offers. 

Compared to its predecessors – and most LCD TVs currently on the market – OLED TVs bring you better image quality (think blacker blacks and brighter whites), reduced power consumption, and much faster response times.

Not only that, but many companies and researchers are actively working to make OLED even better and brighter. OLED TVs are notorious for their dim output, but there's promising news from researchers at the University of Michigan. A team has developed a new electrode that can "liberate" 20% more light from respective screens at the same time as increasing energy efficiency and improving the battery life of OLED displays. Right now this only applies to portable displays –smartphones and the like – but it's a good step for TVs too.

However, one thing that puts many people off OLED TVs is that they often come with a hefty price tag. That’s slowly changing, largely thanks to more affordable models entering the market, including the LG B9 and a smaller 48-inch size for the CX OLED and Sony A9G OLED. With Disney and Marvel openly backing the technology, OLED has never had such a large platform.

The most critical question you need to answer if you’re in the market for a new TV is: should you believe the OLED hype? Our guide below will run you through everything you need to know.

Don’t have time to read a whole article? Watch our quick OLED explainer video instead:

FAQ

OLED FAQ: quick questions answered

  • Is OLED better than LED? They're different. OLED excels in some areas, such as contrast, color accuracy, and black levels – though the low brightness might rub you the wrong way.
  • Is OLED better than 4K? OLED TVs tend to have a crisp 4K resolution, but most 4K TVs don't have OLED panels. Pick and choose as you like!
  • Is OLED better for my eyes? OLED panels emit around half the amount of blue light than equivalent LCD sets, which should reduce the likelihood of damage to your eyes and stop the evening's programming keeping you up at night. You should get those benefits for OLED smartphones too.
  • Why is OLED so expensive? They're expensive and difficult to produce, with a lot of models suffering breakages while on the factory line. (Only the working ones make it to retail, of course.)
  • What's the lifespan of an OLED TV? Any OLED TV should last you years of use. Back in 2016 The Korea Times reported that LG OLED TVs had a lifespan of over 100,000 hours (11 years of constant use).
  • Should I worry about OLED burn-in? Probably not. Image retention isn't a widespread problem, and you're unlikely to be affected – though we have more information on this below.

OLED explained

What is OLED, and how is it different?

OLED stands for Organic Light-Emitting Diode, with "organic" referring to the carbon film that sits inside the panel before the glass screen. 

OLED panels emit their own light when an electric current is passed through, whereas cells in a LCD-LED display require an external light source, like a giant backlight, for brightness.

This backlight is what separated LCD screens from their LED variants. A traditional LCD screen has a backlight (called a cold-cathode fluorescent light, or CCFL) which is uniform across the entire back of the screen.

This means that whether the image is black or white, it is being lit by exactly the same brightness across the panel. This reduces what we call "hotspots," or areas of super bright light, because the actual light source illuminating them is uniform.

This all started a few years back when engineers at companies like Samsung and Sony introduced an array of LEDs as a backlight, which meant that if a certain part of the screen was black then those LEDs behind that portion could be turned off to make it appear blacker.

This is a better solution than a CCFL backlight, but it still has its problems. Since it's a light behind the LCD producing the illumination rather than the LCD layer itself, the illumination is not entirely in-sync with the pixel in front of it. The result is an effect called 'blooming', whereby LED light from bright portions of the image bleeds over into areas of blackness.

This is what separates OLEDs from LCD/LED displays. In an OLED TV display, the pixels themselves are the things producing the light, and so when they need to be black they are able to turn off completely, rather than relying on a backlight to turn off on their behalf.

OLED: what are the advantages?

What is OLED?

Most OLED TVs offer exceptional picture quality, though they need to be paired with a high-spec processor to really do sources justice (Image credit: Panasonic)

The result is remarkably dark blacks in an image, and when you combine this with the bright whites of an OLED panel, you're left with a fantastically vibrant image.

LG and Panasonic, pretty much the most consistent producers of OLED televisions on the planet, like to use the term "infinite contrast" to describe how the self-lighting pixels switch off completely when reproducing black giving it an "absolute" black color instead of a "relative" black that only describes how dark one pixel can get compared to the brightest pixel on the screen.

For years there was a question mark about longevity of OLED panels, while production lines have been impossible to make profitable due to high failure rates. 

But as companies like LG invest billions in development of OLED – with the likes of Philips and Sony joining the fray – its affordability is improving, even if it's still more expensive than competing technologies. Current production issues for LG's most recently-opened TV factory won't be helping that price drop come quicker, either.

The advantages of OLED go beyond simple static image quality, though, to the responsiveness and smoothness of the display itself, meaning gamers and home cinema aficionados are going to absolutely love OLED TV. 

OLED panels are capable of a refresh rate of as low as 0.001ms, which for reference, is around 1,000 times faster than a standard LED-backlit LCD panel, while also being superior to the now-discontinued plasma tech, too.

And, because the lighting source they use is so tiny, the depth of screen sizes has shrunk at the same rate. That means OLED TVs have awesomely deep blacks and bright, peak whites, improved color accuracy as well as smooth responsive motion - and all from a form factor that's just a few millimeters in depth and much lighter than standard TVs.

TVs

LG 2020 TV lineup

LG has a whole host of new OLED televisions for 2020 (Image credit: LG)

OLED: which OLED TVs are out now?

OLED TVs have been on the market since 2012, and a variety of manufacturers have tackled the technology over the years. It used to be the case that OLEDs were produced by just Samsung and LG.

But Samsung dropped the technology over its cost and how difficult it was to produce, and has no intention of restarting production any time soon. More recently, Hisense ditched its OLED focus too.

LG, on the other hand, has been releasing OLED sets consistently over the last few years. The 2020 LG TV line-up has seen a new LG CX Series OLED, an LG GX ‘Gallery’ Series OLED to replace the old LG E9, an LG Signature ZX 8K OLED, as well as many others.

LG also had plenty of new TVs to showcase at the CES 2021 expo, including a budget OLED TV series, the A1 OLED. This was just one among many announcements from the TV maker, including the arrival of a new 42-inch compact OLED size, a brightness boost with the 'OLED evo' LG Gallery Series OLED.

It seems LG is also expanding its range of TV sizes, with an 83-inch size set to come to every new OLED 4K TV LG is releasing in 2021. We heard direct from LG Display itself that an even smaller 42-inch size is on its way for 2021 too.

If you're not big into LG TVs, there are plenty more OLED TVs to look forward to in 2020 too. The Panasonic 2020 TV line-up includes the high-end Panasonic HZ2000 OLED, as well as a more affordable HZ980 series that's new for this year – while more mid-range OLED sets like the Philips 55OLED754 continue to perform well in our tests.

You can also head to our best OLED TVs guide to see the top models we've had the pleasure of reviewing on the site – or our OLED TV deals page for the cheapest sets going right now.

OLED: how much does it cost?

OLED TVs are definitely getting cheaper, but they're still a long way from what we'd call affordable. The prices of new LG TVs start at $1,300 / £1,300, and Panasonic's are usually more expensive still.

The scarcity of OLED TVs on the market means that those small number of players in the market are more or less free to charge exactly what they want. An increase in competition, though, is helping to change that, as is the introduction of a new 48-inch OLED size and a scaling up of production helping to drop a cost of budget OLED TVs.

It's significantly cheaper to buy a 2019 OLED right now, with the budget LG B9 costing just $1,300 / £1,100 and the Philips OLED 754 retailing at only £999 – not cheap compared to some LCD sets, but still the cheapest way to get a decent OLED into your home.

It's definitely worth keeping an eye out for end-of-year sales. Black Friday and Cyber Monday usually have numerous good deals on OLED TVs – and given their usually high starting price, you can often get hundreds discounted at the right time. Cheaper OLEDs, though can still see notable price cuts that bring them more within reach of mid-range buyers.

Burn-in

Do I need to worry about OLED burn-in?

What is OLED burn-in? Burn in, or image retention, is when an image or sequence is played so often and continuously on a television set that it leaves a permanent mark on the panel – obviously not ideal for a home television.

You don't particularly need to worry, as it largely happens only when displaying a static image or sequence on repeat, as with a display unit in a showroom or retail store. You should get several years warranty, anyhow, and we don't see many home cinema fans using their OLED TV in this way.

TV makers like LG are also working to limit the risk of this, with screen saver features, a Screen Shift function that "moves the screen slightly at regular intervals to preserve image quality", and "Logo Luminance Adjustment, which can detect static logos on the screen and reduce brightness to help decrease permanent image retention" (via LG.com).

But if you're planning on leaving your TV for countless hours at a time – say, to parent the children in your absence, or to play the same looping video over and over – then OLED may not be the right panel technology for you.

What's next?

What is OLED?

Burn-in shouldn't worry you, thanks to Screen Shift functions and improving manufacturing processes (Image credit: Toshiba)

What's the future for OLED?

OLED is an expensive panel technology that has finally managed to gain traction – after spending so long as an outlier than we wrote an opinion piece in 2014 about how the technology might be dead.

Obviously that didn't turn out to be the case, and we're seeing plenty of stunning OLED models hitting the market, even if price points are still taking an age to drop within reach of regular consumers.

But just because OLED isn't affordable yet doesn't mean it's not getting better. Even at the bottom end, a $1,600 / £1,200 price tag isn't what we'd consider budget, but it's a great deal cheaper than what OLED was retailing for even just a year ago.

That trend is always going to be good news for the consumer, though manufacturers may have other things in mind.

LG's rollable OLED – which unfurls out of a box, either on the floor or ceiling – has now released in South Korea, with a wider release seeming likely in 2021. New form factors like these, including even transparent panels, are forever in the works, though not all of these experimental ideas end up making it to market.

Samsung is one of several TV makers looking to develop what's called QD-OLED: a new type of OLED panel that uses quantum dot emitters to improve brightness. The tech is very much in development, but when it arrives, it could meld the competing QLED and OLED technologies and render previous methods of production obsolete.

Those are obviously grand claims, and we're yet to see these new hypothetical panels put to use – but we'll be sure to keep you in the loop as it does / doesn't happen.

Original reporting in this article was by Jamie Carter.

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