LG explain why OLED TVs are the future

The Korean giant preaches to the converted

by Steve Withers Oct 2, 2014 at 7:29 AM

  • OLED TVs are superior to LED LCD TVs, everyone knows that… right?
    Well amongst the enthusiast community that might well be the case but, when it comes to the general public, the understanding of how an OLED TV works is fairly limited. This confusion probably hasn’t been helped by the fact that many manufacturers routinely refer to LED TVs when they actually mean LCD TVs with an LED backlight.

    To help differentiate OLED from the rest of the pack, the early models such as LG’s 55EA980 and Samsung’s KE55S9C used curved screens. Why curved screens? Well it had nothing to really do with improving your viewing experience or immersing you and more to do with the fact that it was relatively easy to bend an OLED panel. However, even this distinction has been lost as the majority of manufacturers now offer curved LED LCD TVs, leaving the poor consumer bewildered and confused.

    LG 55EC930V

    In reality OLED isn’t just superior to LED LCD TVs, it’s also superior to plasma but with all plasma production now stopped that comparison is largely moot. As an aside, LG did confirm during our meeting that they will cease all plasma production by the end of the year, largely because they can no longer source components. With all the other manufacturers standing on the sidelines when it comes to OLED and Samsung claiming that they can make an LED LCD TV that is ‘superior’ to OLED, LG clearly felt the time was right to remind everyone of the benefits of the technology.

    So to facilitate this we arrived at LG’s offices in Slough for a meeting with their Korean television engineers and a presentation from LG Display - who are now the largest panel manufacturer in the world. The presentation was an excellent opportunity for LG to go into the OLED production process in detail and explain why they feel their approach is the best. After that, they listed the various benefits of the technology before demonstrating them in reality with both flat and curved Full HD OLEDs against Ultra HD 4K LED LCD models from two competitors.

    OK so let’s kick off with a bit of science first, how does an OLED panel work? Well, an electrical charge is passed between a cathode and an anode (which together make a diode), thus stimulating an organic emission layer and creating an exciton (light). Or in other words, when you pass electricity through the organic layer in the OLED panel it illuminates creating the image, hence the organic in OLED (Organic Light Emitting Diode).
    LG are currently the main champion when it comes to OLED and have invested huge amounts in the technology.
    That’s the theory but the problem has been that making large OLED panels in any kind of viable numbers has proved problematic, so much so that most manufacturers have largely stopped trying. There is also the problem of the huge sums required to develop OLED and only LG and their arch rival Samsung are in such a position, financially speaking. So why is that only LG are currently championing OLED? The simple answer is that they feel their approach to OLED production works best.

    To produce an OLED panel there are three stages, creating the TFT (thin film transistor) backplane, the OLED patterning and the encapsulation. LG have chosen to use an Oxide TFT for the backplane, which is what creates the electrical current. For the OLED patterning itself, LG are using WRGB (white, red, green, blue) OLED which they feel offers distinct advantages. Finally for the encapsulation which protects the Oxide TFT and WRGB OLED from moisture and other contaminants, LG are using a Solid Phase Encapsulation (SPE).

    LG believe that the combination of Oxide TFT and WRGB OLED results in a higher uniformity for larger screen sizes and is compatible with existing LCD production facilities. As a result, yield rates have been increased substantially and whilst not currently as high as for LCD panels, they are much closer. LG expect these yield levels to improve further in 2015 and, as a result, they think prices will fall considerably.

    LG 55EC930V

    On their latest generation OLED panels, LG are also using a 2-stack WRGB device. So instead of a single stack of red, green and blue, the latest panels have two stacks, one green and red and one blue. LG say that this approach increases brightness and reduces power consumption through enhanced material efficiency, as well as optimising the colour gamut. Another key development is a self-compensation algorithm which delivers a more stable image on a large-sized OLED screen.

    So if that’s the technology behind OLED panels, what is is that makes them better than anything else? Well there are a number of key areas where OLED TVs have the edge over LED LCD TVs. Firstly, the black levels are simply stunning because, as a self illuminating technology, when you turn a cell off it goes completely black. They are also very bright, so what you have is a very wide dynamic range and a contrast ratio that is almost infinite.

    An OLED panel also has a much wider viewing angle than an LCD screen, 160 degrees compared to 70 to 100 degrees, as well as a response time that is thousands of times faster. An OLED panel is also incredibly thin, just 4-5mm thick because there are only three layers involved as opposed to the multiple layers required for an LCD panel with an LED backlight. OLED panels are also very flexible, hence the reason that the first models were curved, which is easy to do with OLED panels but much harder with LCD panels.

    OLED has superior blacks of course but it also has much better colour fidelity in darker scenes.
    One of the key advantages which doesn't get reported as much is OLED’s superior colour fidelity at lower brightness levels. This is because, once again, OLED is self-illuminating so each of the three primary colours remains pure even in dark scenes. With LCD there is a big drop off in the level of colour fidelity as brightness levels fall because the other two colours will leak into the third, making white and effectively giving colours a washed-out appearance in dark scenes.

    One interesting thing that LG pointed out was that an OLED panel has less blue light in its visible spectrum, which the manufacturer feels is more comfortable to the human eye. They also said that they intended to study the relationship between blue light and eye fatigue in greater detail. We are certainly glad to hear that because, as anyone familiar with our PicturePerfect campaign will know, we have already pointed out that having your TV set too brightly can lead to eye fatigue.

    Once LG had finished explaining the technology behind OLED and the benefits of an OLED TV when compared to LED LCD, it was time for us to see a demonstration. In fairness we were already very aware of the benefits of OLED, having already reviewed two 55” OLED TVs but it was good to be reminded. LG had two demonstrations set up, the first used a 55” Full HD flat OLED screen (actually taken from one of their Gallery OLED models but without the picture frame) against two 55” Ultra HD 4K LED LCD TVs from a pair of competitors.

    LG 55EC930V

    LG started with a clip of Cirque du Soleil before moving on to a scene from The Hobbit and, needless to say, the superior blacks of the OLED screen were immediately obvious, as was the better colour fidelity in darker scenes. The wider viewing angles were also apparent and despite the Ultra HD 4K TVs appearing sharper due to the higher resolution of their panels, the OLED was easily the preferable image. The total lack of haloing around bright objects against a dark background was in sharp contrast to the two LCD panels that were using local dimming.

    The second demonstration used a curved 55” Full HD OLED screen against a pair of curved 55” Ultra HD 4K LED LCD TVs and all the same benefits were immediately apparent. LG seemed to feel that OLED was better suited to curved screens but were largely ambivalent about the current trend. They seemed less convinced by claims of an improved viewing experience or a more immersive image and plan to offer OLED TVs in both flat and curved varieties - thus letting the consumer decide.

    When asked about image retention, LG said that they didn’t feel that actual production models had any issues with image retention or screen burn and they said that they hadn’t received any complaints from actual owners. That said, to ensure that image retention isn’t a problem, the latest LG OLED TVs have a screen wash feature that will clear the panel of any retained images whilst it is in standby mode.
    LG are confident they have solved the traditional OLED problems of image retention, screen burn and colour decay.
    The other issue that has been highlighted in the past is colour decay, especially in the case of blue. Once again, LG feel that their use of WRGB OLED has eliminated this problem and that their OLED TVs will retain 100% of their colour fidelity for 30,000 hours before there’s any decay. In fact, as we have again pointed out in PicturePerfect, putting the TV into the Cinema or Movie mode will increase this and LG think that their OLED TVs optimum performance can be extended to 50,000 hours in Cinema mode and also use even less energy.

    Of course this is all well and good but it means nothing if there are no actual OLED TVs in the shops and in this area LG felt confident they could deliver an effective strategy. Their current curved 55” Full HD OLED TV is already available and, thanks to improved yields, can be picked up for a decidedly cheap £2,000. There’s also the flat 55” Full HD OLED with the picture gallery frame and in November LG will launch their 65” Ultra HD 4K OLED TV, the 65EC970V, which will retail for around £6,499. We had a chance to get a good look at this beauty and there’s no denying it currently represents the zenith of TV technology.

    The 65EC970V uses a curved screen - no surprise there - but it also includes the latest ribbon stand for an improved audio performance with 2.1 sound and 40W of power. It can be wall mounted using provided adapters but it isn’t compatible with a standard 400 x 400 VESA mount. Of course, there's LG's award-winning webOS Smart+ system, too, and the 65EC970V also uses the same six stage upscaler for processing lower resolutions to 4K that is found in LG’s current flagship LED LCD TV, the UB980. Needless to say, the 4K footage looked amazing but thanks to the benefits of OLED technology, Full HD content was almost just as impressive.
    With production yields on the rise, LG expect 2015 to be the year OLED breaks through as a mass market technology.
    So what does the future hold? Well LG are confident they can expand their Ultra HD 4K OLED line-up, with a 55” and 65” flat versions and a 55” and 77” curved versions, as well as a flexible 77” model that will allow you to choose between flat or curved, although it’s a fair bet that won’t be cheap! What is certain is that with improved yields we can expect to see more models and more competitive pricing. In addition, LG Display are busy making OLED panels for other TV manufacturers, especially in China and Taiwan.

    So in conclusion, things are starting to look up for OLED and thanks to LG’s commitment and huge financial investment, 2015 could be the year that OLED finally breaks through as a mass market TV technology.

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