Why only OLED use direct light emission, and on the other hand we only have LCD-based manipulation of backlight? Why can’t we have small LED blubs for each pixel of screen?

Question

\* or have LED for each sub-pixel of screen.

In: 3

Answer 1

After quite the rabbit hole I think I finally understand enough to give a definitive answer.

Fundamentally you need light to be broken down into subpixels. You can either do this with emitters larger than a subpixel passing light through LCD subpixels, or you can use subpixel-size emitters.

Inorganic LEDs are good for LCD panels because of their brightness, but until recently it was impossible to make a backlight of pixel-sized emitters. Panels can be made with extremely tiny Organic LEDs, but they aren’t bright enough to be good as an LCD backlight. However, it’s not significantly harder to make an OLED panel with subpixel-size emitters than it is to make an OLED panel with pixel-size emitters, so we skipped entirely from globally backlit LCDs to OLED TVs with each subpixel having its own emitter.

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LCDs are still less expensive than OLED, so we started making LCD screens with multiple dimmable zones to improve contrast. As LED technology has improved we’ve been able to increase the number and decrease the size of those zones. LCDs only make sense as long as they are less expensive than OLED though, so there’s a limit to how far that can go.

Micro LED is a new (extremely expensive) technology using inorganic LEDs that are small enough to be used as subpixels. This provides some advantages over OLED as LEDs are significantly brighter than Organic LEDs and OLED manufacturing limitations create an upper limit on the size of an OLED screen that doesn’t apply to Micro LED.