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Is OLED the Tendency? LCD is Actually Better in Many Aspects

Recently, most attention of the mobile display market is focused on OLED technologies. Samsung is the most impressive. LG begins to invest heavily in the production line of mobile OLED modules and new factories so as to keep pace with Samsung. At this point, many people seem to think that at least in high-end market of smartphones, OLED screen has become the direction of future development, and meanwhile, traditional LCD screen will gradually retire from the stage.

From the expected shipment of OLED panels, we can see that it will keep growing in the future. But it doesn’t mean that it will lead to the corresponding drop in the demand for LCD panels. Of course, LCD has its own advantages and technological nature, which shows that LCD is not out-dated now, and it even works better than OLED in some aspects.

The question of high resolution

Now few people complain about the screen effect of high-end smartphones. People are generally using phones with QHD resolution together with HDR technology. Thus there is basically no screen with bad effect. Another bigger focus changes to the brightness of the display screen.

The question lies in that either LCD or OLED panels can not provide light output 100% effective. Some lights are likely to be covered by other display components, and likely to get lost. In LCD screen, backlight must work through light filter, which is not efficient. Besides, every pixel control transistor occupies certain space. All these factors hinder the luminescence of pixels. Different backlight technologies such as a-Si or LPTS can change the aperture of pixels. Of course, when the panel manufacturers improve the resolution, more lights will be covered by these transistors with fixed size.

On the other hand, OLED screen is not going to handle this problem very well. Though the forms of light loss are different, every pixel still needs a complicated layer of transistor, which hides in the luminous components of OLED panels. Even so, TFT’s tight grouping will result in energy loss of resistance and capacitance, which means that under higher resolution, more energy is required to drive the same brightness. Meanwhile, it also requires a reflective polarizer. But this method is not completely effective, because it will lead to slight light loss.

Therefore, the higher the resolution of the display, the greater the energy required to drive the display's LED backlight, so as to gain better visibility in sunlight, and the more power the display consumes. The participation of HDR technology further aggravates this problem. The reason is that by making black more black and white brighter, it broadens the dynamic range, but also adds extra consumption to the battery. It is obvious that excessive power consumption will directly affect the users’ experience, but some technological innovations can be used to solve this problem.

The revolutionary changes brought by RGBW and IGZO

Therefore, now there are two ways to approach this problem: reduce the size of transistors, or adopt another way to improve the brightness of display. IGZO can not only significantly reduce the size of transistors and increase the aperture of sub-pixels, but also reduce additional power consumption brought by low-cost a-Si components. It solves most of the problems, but there are not many manufacturers currently that can put such panels into mass production.

Currently, Sharp, one display manufacturer, has mastered this technology, and begins to build super-pixel displays by means of IGZO for virtual reality market. In terms of smartphones, other LCD manufacturers will inevitably move to this technology in the future, as the pressure from increasing resolution is growing, while the output is increasing meantime. LG Display has mentioned that once the technology is improved, the transition to IGZO-TFT begins. But yet we don’t know how long it will take to use such technology in mobile screens.

RGBW display technology such as LG's M+ sub-pixel technology, provides another way of solution. M+ introducse a dedicated white pixel into the red, green and blue parts of the display panel. It will greatly improve the brightness of pixels, which contributes a lot to improving outdoor visibility and achieving HDR effects on small screens.

The color filter of LCD screen is inefficient, thus a lot of lights are wasted when displaying white images in LCD. Then the red, green and blue pixels are required to be turned on. By using the filter layer of white pixels, it means that we can turn off the RGB pixels and reduce the brightness of the display to achieve the same effect. Or it can be said that we can improve the brightness of all pixels.

The contest between LCD and OLED is going on

OCED is developing with a sound momentum this year and huge potential in the future, especially in raising color range and meeting HDR effects. Of course, like OLED, which has received a lot of attention in recent years, LCD technology keeps innovating. As quantum dot technology raises color range, the changes of transistor-level like RGBW can improve the brightness and function. LCD doesn’t show any sign of failure in the contest with OLED.

It is no doubt that all product developers hope to improve resolution to a higher level, especially to meet the needs of virtual reality technologies. Producers provide consumers with HDR content. Then changes will take place in the market layout.

Additionally, don't forget that the battery of mobile products belongs to a key area to consider. Thus no matter which screen technology is adopted by OEM's manufacturers, we won't be surprised. And don’t be surprised if a mixed technology between LCD and OLED mix appears in the future.

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