When is a LED not a LED?

One of the projects I have been working on recently involved looking in more detail at display technologies, as used in computers, phones, TVs, etc. Which was pretty timely as I will need to buy a new TV soon for our house in Italy.

One of the things I learned about was the terminology used in marketing TVs. There are LCD displays, LED displays and now QLED (Quantum-dot LED) displays. It turns out these are all LCD TVs. The only difference is the source of the backlight.

LCD TVs were the original flat-screen TVs (along with plasma displays, which are no longer made). The first versions were backlit with fluorescent lamps. These were later replaced with LED lights to create the so-called LED TV. These have the advantage of being thinner and lighter, and consuming less power. They can also improve the contrast ratio by adjusting the lighting level based on the average brightness of the image.

When I first saw QLED displays being advertised, I assumed they would be “real” LED displays where the image is created by turning on red, green and blue LEDs in each pixel. But no, they are just another LCD display using quantum dot LEDs to provide improved backlighting.

There are now true LED displays available based on OLED technology. These are currently very expensive but are much brighter with much deeper blacks. They should consume less power than LCD displays for average images although they can consume more power for an image that is mainly white.

The prices of OLED TVs should drop quite quickly as fabrication techniques improve and scale up. So I think I will wait a while before buying a new TV.

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