How LCDs with tiny diodes could outperform OLEDs


LCDs with mini-LED backlighting will in future find their way into large TVs as well as monitors and notebooks; they should also ensure high-contrast displays in smartphones as well as in cars. By deliberately dimming the small, evenly distributed diodes on the back of the display, i.e. reducing their brightness on dark picture content and increasing it on bright ones, the visible contrast can be increased enormously.

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LCDs with so-called Full Array Local Dimming (FALD) have been using the same principle for a number of years. You optimize the contrast with a few tens to a few hundred dimmable zones. You can find FALD backlights in better TVs as well as in high-quality monitors.

The mini-LEDs should now significantly increase the number of zones – instead of a few hundred, tens of thousands of diodes are used, which are grouped in a thousand and more dimmable zones. The first TVs with mini-LEDs will have fewer than 2,000 zones, but the number could rise to 5,000 individually dimmable segments by next year, believes Danny Tack, who is responsible for TV picture quality at Philips.

So far, organic displays have succeeded in increasing the contrast best – each individual OLED pixel can be dimmed or switched off in a targeted manner. The same applies to displays with micro-LEDs, which use a tiny diode for each pixel. However, micro-LED displays are still a long way off; their production is currently far too expensive, especially for large screen surfaces.

The switch to mini LEDs for the backlight is also so interesting because it gives the established, inexpensive LCD technology a new boost. Many had already written off LCD TVs in the high-end sector, good smartphones are almost entirely composed of OLED panels, and the two Korean top dogs Samsung and LG even wanted to say goodbye to LCD technology completely in 2019: The first production facilities were sold or closed. They have put these plans on hold and most of the factories will continue to operate for the time being.

The Chinese display specialist TCL showed its first LCD televisions with a backlight made of mini-LEDs three years ago.

If mini-LEDs are used in the LCD backlight, a significant improvement in the image can be achieved with sophisticated manufacturing processes. The production of large OLED panels, on the other hand, continues to pose problems, which is why the quantities are limited and the costs are high. Chinese display specialists like BOE and CSOT have not yet managed to mass-produce OLEDs.