[Yamaki]

I spent quite a bit of time reading up on current display technology and attempting to discern the differences, at least on paper, that are key as part of a purchase decision.

After some hours of reading different reviews and technical evaluation reports, I decided that for me the key criteria were:

1. Display resolution of 3840 x 2160

2. HDR capable

3. HDCP specification 2.2 or better

4. Backlighting method

5. Native refresh rate

The first three criteria are simple Yes or No ratings.

Backlighting methods are a bit more complicated. All LED TVs are really just LCD TVs that use LEDs for their backlight. This backlight creates the light that allows the LCD to create an image. However, there are multiple ways these LED backlights can be arranged, and that arrangement can have a dramatic effect on picture quality.

Many LED LCDs on the market today are edge-lit, which means the LEDs are in the sides of the TV, facing in toward the screen. Because the light is brightest nearest the LEDs, it's common for edge-lit LED LCDs to appear to have poor uniformity. This is especially noticeable on dark scenes, where areas of the screen will appear brighter than others. Corners or edges can have what looks like tiny flashlights shining on the screen. This technology is still found in quite a few screens today.

Then there is the backlit arrangement where all those LEDs face in towards the front of the screen from the back. Backlit LED arrangements began emerging into the marketplace 5 or 6 years ago. Initial versions provided plasma-like black backgrounds but, by today's standards, were not up to providing the level of color reproduction and detail we all look for.

Fast forward a few years and the backlit LED technology looked quite different and started to drop in price. This improving feature was named OLED (organic light emitting diode) and you saw all sorts of trade names pop up. Recently, an added a feature called "local dimming" came on the scene which many feel is today's ultimate LED LCD, offering performance that rivals the better plasmas. Like the "direct-lit" TVs, these have their LEDs behind the screen (the image above for direct-lit works as a visual aid for this type as well). The full local-dimming aspect means the TV is able to dim zones behind the dark areas of the screen in fairly specific areas to make the image really pop, drastically increasing the apparent contrast ratio.

All through this back lighting evolution the LEDs became smaller and smaller...and now we see QLED technology making a bid to be the big dog in TV technology. QLED, I believe, is trademarked by Samsung and they describe it as their quantum dot light emitting diode technology.

I guess it's all about how many tiny LEDs you can squeeze into the array.