Displays with Organic Light Emitting Diodes, OLEDs, are the most interesting and promising new display technology in over a decade — possibly ever. In a span of just a few years this new display technology has improved at a very impressive rate, first challenging and now surpassing the performance of the best LCD and Plasma displays. OLEDs are an entirely different and new form of display technology — they are very thin solid state displays that emit coloured light directly, while LCDs use a liquid crystal that regulates light transmission from a separate backlight, Plasmas use an ionised gas with phosphors, and CRTs use an electron beam in a vacuum with phosphors.
Just how good is OLED TV technology? DisplayMate's Dr Raymond Soneira put LG's latest OLED offering through its paces. You may never watch TV the same way again.
While there have been quite a few experimental and prototype OLED displays shown over the last 5+ years, including an 11-inch 960x540 pixel TV by Sony, OLEDs first appeared in actual consumer products as 4-inch to 8-inch displays in Smartphones and Tablets beginning in 2010. However, producing a large screen OLED TV is considerably more difficult for many reasons — for one, a 55-inch TV screen has 121 times the area of a 5-inch Smartphone. This results in major production and technology issues, particularly in manufacturing yield and cost.
There are currently only two manufacturers that have begun production of OLED TVs: LG and Samsung. The TVs are based on somewhat different OLED technologies. This article examines the LG OLED TV. LG provided DisplayMate Technologies an early production OLED TV (model 55EA9800) with a 55-inch (1.4m) screen to test and analyse for this article. Over the past few weeks we have performed an extensive series of Lab tests and viewing tests to evaluate the LG OLED TV technology and picture quality, and also to compare it to existing LCD and Plasma TVs. We'll cover these issues and much more, with in-depth comprehensive display tests, measurements and analysis that you will find nowhere else.
This will be a two-part article: this first article is devoted to explaining the unique performance capabilities of the OLED TV, with only general comparisons with LCD and Plasma TVs. In Part II we will provide detailed Lab measurements and side-by-side performance comparisons with an LCD TV and a Plasma TV. Before we begin the technical analysis, here are several other important issues.
There are No LED TVs!
The first thing we need to clear up is the confusion created by the marketing of "LED TVs" — there aren't any! The so-called LED TVs are just LCD TVs that have a backlight that is made of white LED lights. The LEDs are not the display, just the backlight, nothing more! OLEDs are an entirely different emissive imaging display technology (that doesn't use a backlight). Unfortunately, many people think they already have an LED/OLED TV at home, but they actually have an LCD.
Several design features immediately standout with this OLED TV: it has a slightly curved screen, the screen is incredibly thin at just 0.16 inches (4.3mm), it has an elegant curved transparent base, a dark black rimless screen without a bezel, and a small 0.4-inch (1cm) flush border surrounding the picture to the outer edge of the screen. Even the rear of the TV looks elegant with a patterned design on a high-tech Carbon Fibre Reinforced Polymer that provides a light weight and high-strength backing for the OLED screen.
The screen on the TV is slightly curved, which has generated lots of commentary. One reason for curving the screen is just because it can be done with OLEDs, while LCDs and Plasmas cannot. So it's a design element that provides some flair and notoriety. But the screen is just slightly curved, with a radius of curvature of 5m, so the corners of the screen are only 1.4 inches (3.6cm) forward of the rear (centre) of the screen — so it's not a large geometrical effect. The promotional photo at the top of the article is designed to emphasise the curves… The photo below is closer to an actual frontal view.
Whether you prefer a curved or flat screen is primarily subjective, but the slightly curved screen does provide some objective advantages. First and foremost, the concave screen shape cuts down on reflections from surrounding ambient light two ways: by reducing the screen's 180-degree opening angle, which eliminates reflections from some ambient lighting on the sides, and also from specular reflections off the concave screen, which directs some reflected ambient light from behind the viewers away from their line of sight. This is very important for a display technology that produces excellent dark image content and perfect blacks — because you don't want that spoiled by ambient light reflected off the screen.
A second and more subtle point: people sitting off to the sides away from the central sweet spot get a somewhat better viewing experience because the curved screen accommodates their viewing direction better and reduces the stretched keystone (trapezoidal) shaped image that is seen with flat screens viewed at an angle from the sides. The flip side is that the top and bottom of the screen and picture don't look perfectly straight, but rather appear with a slight subtle curve — it's a small geometric effect, only a 1.5% curve (difference between the centre and sides) is seen at a 2.4m viewing distance. It's more apparent when the room lights are on, but much less so in low ambient lighting, which is the best way to watch the TV. I found that if I didn't make a point of looking for the slight curvature, I didn't notice it. For me, the advantages of reduced reflections and better side viewing outweigh noticing a slight curvature, but it is nonetheless still a subjective call.
Brand new technologies always start out very expensive — and this first generation 55-inch (1.4m) LG OLED TV is no exception at $US9,999 US (€8,999 Euros), which is comparable to the initial pricing for large Plasma TVs when they first came out. Given the limited production, even at this high price point LG will still be able to sell every one they can make. As the OLED TV technology is refined and production yields increase the price will steadily come down. At some time in the future — which will take years — OLED TVs will become cheaper to make than LCDs and Plasmas because they are considerably less complicated to manufacture and assemble. An LCD display panel, for example, consist of dozens of separately manufactured components that are assembled like a car on an assembly line, whereas OLED displays are manufactured more like a large semiconductor chip.
Overview and Summary of Results
OLED provides a number of major technology enhancements for displays and TVs: high Peak Brightness together with perfect Blacks, Infinite Contrast Ratios, very wide Viewing Angles, and very fast Response Times without visible Motion Blur. But what makes this TV absolutely stunning is combining that with a very accurate factory calibration that takes full advantage of the OLED display technology and delivers picture quality and accuracy that is visually indistinguishable from perfect based on our extensive Lab tests. Below is an Overview and Summary of the extensive Lab and Viewing Tests followed by the LG OLED TV Conclusions.
We have also provided a Lab Measurements and Technical Analysis section that has detailed technical information and data on: White Sub-pixels, Brightness and Contrast Ratio, JNCD Just Noticeable Colour Difference, Colour Gamuts, Absolute Colour Accuracy, Intensity Scale and Image Contrast, Colour Tracking Accuracy, Changes with Viewing Positions and Viewing Angles, Response Time and Motion Blur, Stuck or Dead Pixels, Screen Saver, and Power Consumption.
LG OLED TV Technology
This LG TV has some unique OLED technology. First of all, rather than laying out a matrix of separate Red, Green, and Blue OLED sub-pixels throughout, the TV has a uniform set of WRGB sub-pixels that are made as a stack of various colours of OLEDs. This approach simplifies the OLED production, improves yields, and lowers the manufacturing cost. A set of Red, Green and Blue sub-pixel filters, which LG calls a Colour Refiner, recovers the desired Red, Green and Blue OLED colours for each sub-pixel. This approach also improves Viewing Angle performance, which is outstanding. LG has also added a 4th clear sub-pixel to every pixel, which produces pure White. This increases the display's power efficiency and also improves colour accuracy and colour management. See the Lab Measurements and Technical Analysis section for more information on White Sub-pixels. Lastly, the OLED pixels are all driven by an Active Matrix IGZO Metal Oxide backplane. The Refresh Rate for the display is 120 Hz. Not surprisingly, it's a cutting edge state-of-the-art display throughout.
This TV comes with 6 different preset Picture Modes for viewers to choose from: Vivid, Standard, Eco, Game, ISF Expert and THX Cinema. The THX Cinema and ISF Expert picture modes both deliver close to a visually perfect TV calibration that we will examine in detail below. The Certified THX Cinema mode has no user adjustable controls or options, including brightness, and is designed for viewing under specified low ambient light viewing conditions. The two ISF Expert modes provide lots of user adjustments, but the TV is so well calibrated that "OLED Brightness" and Colour (saturation) are the only two that should be adjusted based on individual viewer preferences. The Standard, Eco, Game, and Vivid Picture Modes offer a peppier picture with more colour, image contrast, and dynamic image processing. The TV also has 3D modes, and it comes with four pairs of light weight designer 3D glasses that look and wear like fashionable sunglasses. We'll cover these modes in depth below.
This OLED TV delivers a Peak Brightness that is comparable to the brightest large screen LCD TVs for TV, movie, and video content. While the THX Cinema mode has an intentionally low Luminance of 135 cd/m2 for viewing under low ambient lighting, the equally well calibrated ISF Expert modes go up to 308 cd/m2, which is impressively bright for an accurate calibration. The Standard, Vivid, Game, and Eco modes deliver up to 372 cd/m2. When using the TV for watching typical web and computer content, which often have lots of bright white content, the Peak Brightness can decrease to 110 to 140 cd/m2, which is bright enough for comfortable viewing in all but the highest ambient light. See the Lab Measurements section for details.
Colour Calibration and Accuracy
The detailed Lab Measurements section shows that the THX Cinema and ISF Expert modes are calibrated so accurately that they are visually indistinguishable from perfect. The Colour Gamut is 99% of the sRGB/Rec.709 Standard. The White Point, Primary Colours, Reference Colours, and Colour Tracking Accuracy are all close to 1 JNCD (Just Noticeable Colour Difference), so the eye sees them as visually indistinguishable from perfect — which was confirmed in the Viewing Tests. See the Lab Measurements section for details and explanations of JNCD and Absolute Colour Accuracy.
Viewing Angle Performance
The best place to watch any display is with the viewer sitting directly in front of the centre of the screen at eye height — which is called the "sweet spot" and only one person can be there. Other viewers may see a slight to substantial degradation depending on how far away they are from the sweet spot. In many cases TV viewers watch from 30 degrees and occasionally as high as 45-degree Viewing Angle. All displays show some variation in Brightness, Black Level, Contrast Ratio, Intensity Scale, Gamma, White Point, Colour Gamut, and Colour Shifts with Viewing Angle. The variations are generally quite large for LCDs. For the LG OLED TV the Lab Measurements show no visually detectable variation in picture accuracy for typical TV watching Viewing Angles up through at least ±30 degrees. See the Lab Measurements section for details.
No Motion Blur
For the OLED TV high speed screen shots of fast moving test patterns show absolutely no visible Motion Blur or latent images from any previous refresh cycles. A comparison screen shot for an LCD TV shows considerable Motion Blur. For details and the screen shots see Response Time and Motion Blur in the Lab Measurements section.
Before, during, and after the Lab Tests we spent a considerable amount of time viewing real TV, movie and video content, lots of digital photos, plus web and computer content via its Smart TV interface. We also invited over a dozen people to come watch and provide their impressions of the OLED TV while viewing their chosen TV shows and Blu-ray movies. We also looked at lots of personal digital photos on this accurately calibrated TV, which is important because people generally know exactly what the photos actually look like. We carefully setup the viewing area with adjustable low to medium ambient lighting, a viewing distance of 2.4m and the centre of the TV at viewing eye height level. The viewer comments were unanimous, "this is the best TV we have ever seen." It's the result of an excellent calibration that delivers accurate colours and excellent image contrast together with perfect Black Levels, which was particularly noticeable with dark content and dark picture detail that is seldom reproduced well by other display technologies (see below). Simply stated, the picture quality is absolutely stunning!
3D Picture Quality
This OLED TV also has 3D modes using LG's 3D FPR technology with Passive 3D Glasses. Back in 2011 we did an article on 3D TV Technology with in-depth objective scientific comparisons and analysis, including extensive lab measurements and viewing tests together with quantifiable 3D Visual Sharpness Tests. Our 2011 study only used LCD TVs. As a result, we expected this LG OLED TV to perform better in 3D because of its improved Black Levels, Contrast Ratio, Response Time, and screen optics. We didn't do any 3D Lab measurements this time, but viewing the same set of 3D movies mentioned in the 3D TV article produced even better 3D as we expected. The Avatar and IMAX 3D movies that we watched were immersive and gorgeous!
Comparison with LCD TVs
LCDs are currently the dominant display technology because they do lots of things very well. One area where LCDs are clearly number one is in Peak Brightness (because their separate backlight can be easily brightened). The LG OLED TV has a Peak Brightness comparable to the brightest LCD TVs, but only for Average Picture Levels (APL) below 30%, which is typical for essentially all TV, movie and video content. Above 30% APL, which is common for web and computer content with white backgrounds, the OLED Brightness decreases but the LCD Brightness remains unchanged. Other than Peak Brightness at high APL the OLED TV significantly outperforms all LCDs in every other category including Black Levels, Contrast Ratio, Viewing Angles, and Response Time. We'll cover LCD TV performance in detail in Part II of the article.
Comparison with Plasma TVs
Plasma TVs have a smaller market share, but they are often preferred by video enthusiasts over LCDs because of their superior Black Levels, Contrast Ratio, Viewing Angles, and Response Time. However, Plasma displays produce visible image noise at dark intensity levels, which compromises their picture quality. The OLED TV clearly outperforms Plasmas in all of these categories. Plasma TVs typically have peak Brightness (Luminance) levels of 100 to 200 cd/m2, whereas the OLED TV produces roughly double that value, even on the accurately calibrated ISF Expert picture modes. OLEDs will clearly become the preferred technology for video enthusiasts. We'll cover Plasma TV performance in detail in Part II of the article.
In-depth Technical Information
We have also provided a Lab Measurements and Technical Analysis section for in-depth technical information and data on: White Sub-pixels, Brightness and Contrast Ratio, JNCD Just Noticeable Colour Difference, Colour Gamuts, Absolute Colour Accuracy, Intensity Scale and Image Contrast, Colour Tracking Accuracy, Changes with Viewing Positions and Viewing Angles, Response Time and Motion Blur, Stuck or Dead Pixels, Screen Saver, and Power Consumption.
LG OLED TV Conclusions
OLEDs are the most interesting and promising new display technology in over a decade — possibly ever. In a span of just a few years this new display technology has improved at a very impressive rate, first challenging and now surpassing the performance of the best LCD and Plasma displays. OLED technology provides a number of major technology enhancements for displays: high Peak Brightness together with perfect Blacks, Infinite Contrast Ratios, very wide Viewing Angles, and very fast Response Times without visible Motion Blur. Equally impressive is that OLEDs have now moved up from small mobile displays into large TV screens for the living room.
But what makes this LG TV absolutely stunning is the combination of OLED display technology together with a very accurate factory calibration that delivers picture quality and accuracy that is visually indistinguishable from perfect based on our extensive Lab tests — a commendable and impressive achievement!
Another notable milestone is that this first generation OLED TV is already outperforming the established and highly refined LCD and Plasma technologies. Normally it takes at least 5 years for that to happen, so a lot has been going on behind the scenes. The biggest remaining challenge is to improve OLED TV production so that the price can come down as quickly as possible to more affordable levels. OLED TVs will eventually become cheaper to make than LCDs and Plasmas because they are considerably less complicated to manufacture and assemble. I can't wait to see that happen.
See the Lab Measurements and Technical Analysis section for in-depth technical information and data on the LG OLED TV.
This article has been republished with permission from DisplayMate.com, where it can be read in its entirety.
Dr Raymond Soneira is President of DisplayMate Technologies Corporation of Amherst, New Hampshire, which produces video calibration, evaluation and diagnostic products for consumers, technicians and manufacturers. See www.displaymate.com. He is a research scientist with a career that spans physics, computer science and television system design. Dr Soneira obtained his PhD in Theoretical Physics from Princeton University, spent five years as a Long-Term Member of the world famous Institute for Advanced Study in Princeton, another five years as a Principal Investigator in the Computer Systems Research Laboratory at AT&T Bell Laboratories, and has also designed, tested and installed colour television broadcast equipment for the CBS Television Network Engineering and Development Department. He has authored over 35 research articles in scientific journals in physics and computer science, including Scientific American. If you have any comments or questions about the article, you can contact him at [email protected].