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Why is OLED the Next-generation Display?

  • Date Posted2019.04.12
  • Views653
  • BLOTER
  • Genius


“Vivid Image Quality that Creates the Illusion of Reality” 


This phrase has been repeated for decades when promoting TVs or monitors. It’s becoming a cliché, but brands have continued to use it, varying the no_expression little by little. In other words, the display technology is still evolving to mimic “reality.”


There’s nothing strange about anticipating brighter, more vivid images. Modern people spend most of their time staring at a screen while they’re awake. They work and study on the computer all day and watch TV during breaks. It is part of our daily life now to keep smartphones in our hands until we fall asleep. When we talk about TVs, monitors, and smartphones, we constantly discuss better picture quality. One of the biggest demands from new devices is the display.

 

| This transparent display shows the background behind it. It is produced by directly depositing self-illuminating semiconductors.


The evolution of displays and devices with LCD and its limitations


Displays have been rapidly developed. The demand for better display technology constantly creates new screens. The evolution of displays is also about the process of leading with the latest technology, not just upgrading the picture quality. It's the key element that transforms the form factor of devices. To date, LCD has been taking that role. By displaying a variety of colors on a thin screen, LCD changed the shape of the PC to a laptop and replaced the telephone with a smartphone. Needless to say, the shape of the TV has changed. LCD has played a big role in transforming our lives by replacing TVs, computers, and phones in the past 20 years.


LCD started with a completely different mechanism from the “fat” CRT screen. It was thin and vivid, and the image quality was also superb. Over generations and improvements, the LCD technology has reached its peak. Now, what is the new direction for the LCD technology to pursue as a display? The latest issue is color. Since the advent of the color TV, every screen in the world has emphasized the resemblance to reality. This is because the color we see on the screen is different from what we observe in reality.


| The basic mechanism of LCD: the light from the backlight (BLU) passes through the TFT and the color filter to emit color and light.


Previously, the quality of the picture was based on resolution, which is a measure of how clear the picture is. However, now that the UHD era has begun, the 4K and 8K formats have shifted away from these standards for resolution and clarity. In contrast, the problems with color are just starting to be realized due to technical limitations.


Until now, we have recalled the original images upon seeing the result of its mechanical no_expression, instead of seeing the actual color in reality. The displays could not portray red as truly red, nor blue as truly blue. There has also been problems with the broadcasting mechanism of color TV content in past decades, but the displays have not been able to depict true colors, either. This is what they talk about when experts discuss the percentage of RGBs and whether displays can represent the DCI-P3 standard. For along time, we have been matching the blurred screen and the actual colors from reality in our brains.


In particular, LCD has a fundamental weakness. It's the backlight. In fact, it is not just a weakness but the very foundation of LCD technology. All displays must emit color and light to be visible to our eyes. LCD displays utilize the three primary colors R (red), G (green) and B (blue) to formulate al other colors, then add light from the backlight to transmit the image to our eyes. The backlight can also be viewed as a fourth color in addition to R, G, and B, as it emits white in color. This is why the initial models of LCD, which are similar to fluorescent lamps, tended to be tinged with yellow or become darker over long periods of use.


The LED backlight was invented to resolve this issue, as LEDs rarely change in color or brightness. Still, it was difficult to express the correct color. In recent years, several technologies such as DCI-P3 and Dolby Vision have evolved to provide a wider range of colors, but since the backlight determines the amount of light, it is difficult to simultaneously express both light and dark areas simultaneously. Light would leak and cause the black color to have grayish hues.


However, it is difficult to bend or change the shape of LCDs, and they are no longer considered slim in terms of today’s standards. Also, the liquid crystal has a relatively slow reaction time. In particular, the burn-in effect is common in cold weather because the liquid crystal would freeze. Though it has improved significantly, there still remains the problem of narrow viewing angles that allow for an optimal viewing experience only within a certain range.


Efforts to address these problems have continued for a long time and are seeing further advances. The recently introduced quantum dot display has also increased the level of expressing color using quantum characteristics, but it still retains the technical limitations of LCD.


OLED: Emitting Color and Light Simultaneously


Nevertheless, LCD is still a decent display. It is stable and still excellent in image quality. However, it has obvious technical problems that can’t be solved. Various new technologies were developed, such as Quantum dot display, and labeled as the “next-generation display,” but now the most realistic next-gen display is OLED. It is a technology that solves most of the problems that we have encountered in the past. OLED is short for “Organic Light-Emitting Diode.” The name doesn’t quite give you the sense of what the technology does. In short, OLED is a display with “self-illuminating” pixels. There is no backlight. For example, in a 4K resolution UHD TV, 3,840 horizontal and 2,160 vertical pixels all produce color and light individually. In other words, 8.29 million dots are emitting color and light independently.


| OLED has a slim and simple structure because each pixel simultaneously emits light and color. The shape can be easily transformed depending on the material deposited.


For example, when depicting an image of a bonfire on a dark beach, the LCD display becomes confused. To express the blazing fire, it has to turn on the backlight brightly, but when the backlight is bright, the stark darkness of the beach can’t be portrayed. Because OLEDs are self-illuminating, the pixels that depict the bonfire are brightly lit on their own, while the pitch-black areas don’t light up at all. The grayish parts can be expressed as gently as they are. Because each pixel emits the exact color and light accordingly, the light representation is similar to reality. This is the technical basis for expressing accurate colors.


Semiconductors and Image Quality 


Although OLED displays are more expensive than LCDs, they are quickly establishing themselves in the market. There is a firm recognition of OLED as a premium display. Not only are the OLED displays more advanced in terms of technology, they simply have good image quality.


The most distinguishable aspect of the OLED is its no_expression of black. The way the OLED display depicts black color is very simple. It doesn’t turn anything on; no color, no light. To express black, LCD blocks the bright backlight from leaking to the screen forward. But it can’t be totally covered, which results in spots of bright light. It's not black, but something that resembles black. In other words, OLEDs are very effective for viewing in a dark places. It also depicts the shadowy parts of the content in incomparably more elaborate ways than LCD screens.


| The uniform and precise deposition of semiconductors on OLED devices is at the heart of OLED technology. By incorporating this deposition technique, displays can be bent and formed into various shapes.


The color of the OLED screen looks darker and clearer because the black color is depicted much better. It's not that the resolution is high, but the color is crisp and clear. If you look at vibrant and colorful screens in a bright place, LCD is good enough, but in dark spots, OLED shows a much better display.


This difference doesn’t simply stop between displays. In recent years, video standards have been emerging to allow more accurate no_expression of color and brightness without exaggerated vibrancy. Dolby Vision or HDR (High Dynamic Range) 10 are such formats. Because these express a wider range of colors and brightness, you can see a more realistic image on such displays. As such formats are still in their infancy, they often use sample videos that display differences more prominently. When you watch their videos, you are bound to immediately react to how vibrant and dazzling the colors are. This may sound a bit unlikely, but with displays that have better representation of reality, you can see more realistic images.


 

Soon, when HDR standards become the norm through the UHD TV transmission system, and digital cameras and smartphones are capable of filming in HDR, the images we see will look much closer to reality. YouTube and Netflix are already actively embracing HDR content and adding it to games, including PC games and consoles such as PlayStation 4 Pro and Xbox One X.


At this moment, we must pay more attention to the possibilities of OLED, as we focused on the LCD in the past. The arched processing method called “Curved" has been in development for a long time already. OLED is breaking existing stereotypes with paper-thin displays and using the screen as a speaker diaphragm. The evolution of display, which seemed to have hit a dead end, is back on the progressive track with the imminent future of OLED.



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