Oled technology is very different from LCD technology (Liquid Crystal Display, or liquid crystal screens) used for several decades and still present in many televisions, even at the top of the range. The LCD is the foundation of Mini-Led screens, for example. Oled screens do not use a backlight system. Each pixel emits its own light, which allows it to go down to a perfect black level, for unparalleled display precision. However, OLED televisions do not deliver as high a brightness as that of the most high-end LCD models, in particular televisions equipped with a Mini-Led backlighting system, but this might well change with the arrival of new panels. Oled Meta, the third generation of Oled tiles, using billions of micro-lenses and specific algorithms.
Constantly increasing luminosity
The first LG 55EA980V Oled TV that we tested was content with a peak brightness of 300 cd / m², but HDR content did not yet exist.
In 2013, the first OLED Full HD televisions were content with a peak brightness of around 300 cd/m² (see LG 55EA980V test) sufficient for SDR content. It took until 2017 to see Oled televisions exceed a peak brightness of 700 cd/m² (see the LG 55C7V test) and even 2022 to see Oled televisions come to tease 1000 cd/m² with the use of panels Oled EX from LG Display coupled with a cooling system. The LG 65G2 Oled TV thus displays a peak brightness of 998 cd / m².
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From 2019, Panasonic exceeds a peak brightness of 900 cd / m² with its Oled Professional Edition panel equipped with a cooling system (an aluminum plate placed at the back of the Oled panel).
Only Panasonic manages to do better by using the same panel since its Panasonic TX-65LZ1500 television displays a peak brightness of 1101 cd / m². It must be said that the Japanese manufacturer is at the origin of the dissipation cooling system on OLED televisions; a system already present on the Panasonic GZ2000 in 2019, whose peak brightness reached 952 cd / m².
QD-Oled to the rescue
On the left, LG Display’s WOLED technology, with a white Oled sub-pixel as the light source and color filters for the red, green and blue sub-pixels. On the right, the structure of Samsung Display’s QD-Oled, with a blue sub-pixel as the light source and red and green quantum dot filters for the other two sub-pixels.
In 2022, Samsung Display markets its first QD-Oled panels (Quantum Dot Oled). It is an OLED panel on which a quantum dot filter (Quantum Dot) is applied. Excited by the light emitted by the organic blue (Oled) sub-pixels, these quantum dots display more saturated red and green colors, while improving energy efficiency. When the first QD-Oled televisions from Sony and Samsung came out, we therefore expected to see a peak in brightness on the rise, but this was not the case. We measured a peak brightness of 965 cd/m² on the Sony XR-55A95K and 972 cd/m² on the Samsung QE55S95B.
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The difference with LG Display’s Oled technology is actually in the color saturation. QD-Oled televisions display more saturated red and green primary colors, allowing them to display 84% of the colors in the Rec.2020 color space, compared to 75% for the best televisions equipped with Oled panels manufactured by LG Display . This gain will not be visible on all content. Indeed, if the Ultra HD standard makes good use of the Rec.2020 colorimetric space, most films are calibrated on the DCI-P3 colorimetric space. There are only a few movies that truly exploit Rec.2020. We can mention the animated film Vice versa from pixar, Aquaman, The Greatest Showman or the remastered version of Fifth element.
5117 micro-lenses per pixel for a total of over 42 billion micro-lenses.
In order to drastically increase the brightness of Oled panels, the manufacturer LG Display has developed a system of micro-lenses to optimize light diffusion, and above all to reduce losses. The technology is quite incredible and hard to imagine since each pixel of a 77-inch model is equipped with 5117 micro-lenses for a total of over 42 billion micro-lenses.
Steps in the manufacturing process of the MLA (Micro-Lens Array) filter.
The micro-lenses are applied using a photolithography process. A mask limits the reaction to the precise location of the sub-pixels. The slab is then exposed to rays and then the materials are developed. Then comes the plasma etching phase which eliminates the photosensitive coating layer. This layer forms an ash which is sucked up using a vacuum pump.
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On the left, a conventional Oled panel. On the right, an Oled Meta panel with its MLA (Micro-Lens Array) micro-lens filter.
In practice, the MLA filter makes it possible to reduce the losses induced by internal reflections. On the illustration, we can see that the main pane reflects part of the light inside the slab. On the Oled Meta panel, the MLA filter prevents light from returning inside by reflecting it outwards. The convex shape of the micro-lenses also greatly improves the viewing angles (between 50° and 80°) while benefiting from a 60% increase in brightness.
LG Display also uses the Meta Booster algorithm which precisely analyzes the brightness information and makes adjustments in each scene so that the OLED can display the maximum brightness accurately.
The sub-pixels of the Oled Meta panel photographed with an electron microscope at 200x on a Philips OLED908.
The first results are promising since the Oled Meta panel has already delivered its first measurements. During the presentation of its MZ2000 television, Panasonic carried out live measurements on a 10% window in Filmmaker mode and the peak brightness was measured at 1466 cd/m². For his part, our colleague Vincent Teoh carried out measurements on a pre-series Oled Meta panel. It measured a peak brightness of 2110 cd/m² on a 3% window with a color temperature above 9000 K, while in another videothe peak brightness reaches 1514.5 cd/m² with a temperature of 6500 K on a pre-series model of the MZ2000.
A peak in brightness of around 1500 cd/m² represents an increase in brightness of almost 50%, which is clearly the greatest gain in brightness observed between two generations of OLED panels. Finally, the Oled Meta panel also introduces a new Vanta Black anti-reflective filter reducing reflections by around 30%, which should allow televisions equipped with this panel to tease the QD-Oled models, which until then were better at processing reflections.
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