Let me first explain how the technologies work and then get into that.
A normal LCD is just a light shutter. The shutter is a filter of light and based on electrical signal can be told to filter a bit or a lot. It does this by changing the orientation of a polarization field which when at 90 degrees blocks light and when at 0, does not. The light source is constant in the form of the "back light." The back light is either fluorescent or LED. The latter sets ore incorrectly called LED TVs. The right name would be LED backlit LCD as the structure of the TV has not changed. Only the constant light source.
Because the picture is created using a front filter, some amount of light can still leak through because the backlight is still on and no filter is perfect. A partial solution is to dim the backlight. This is the so called "local dimming" solution. The challenge here is that a 1080p set has 2 million pixels. So for this to work, you would need to have 2 million sources of light which is very impractical. Current sets have something like 32 to 256 regions which approximates the same but can still lead to such artifacts as halos as white pixel with dark background can have a glow due to backlight region being much larger than the individual pixel. There are good and bad schemes here but ultimately they all have similar problems.
LCDs are also directional due to use of the polarization filter as just explained.
Plasmas devices likewise have issues in that they require a residual charge to make them work. This residual charge causes them to not be able to fully display black as black. Pioneer's claim to fame was to tame this problem in successive generations of their displays. The process was taught to be too expensive to manufacture in volume and hence the reason they pulled out when they noticed the costs were spiraling down for competing solutions (and the company was having substantial financial problems at the time being much smaller than other Japanese companies).
OLED is an entirely different animal. It is actually a light emitting device. This means that if you tell it to display black, i.e. nothing, it does exactly that. It shuts off the drive to the pixel and it will go black -- just like what happened with the CRT sets of the past. The problem with it is that it can't produce as much light as a normal LCD display which can essentially have arbitrary amount of light behind it. The other problem has been yield. The former appears to have been solved by LG for example by inserting a white element in there. Cheap projectors deploy this technique to get brightness but this usually comes in the form of compromised black levels and colors. Yield issues could come in the form of bad pixels which have to be manually repaired in the factory. The first generation 1080p LCD sets were enabled this way which made them very expensive. The other issue which I worry about is color and brightness uniformity. With every pixel being a light source, if there are process variations, we could get differing performance in each. OLEDs are heavily used in today's smartphones and they do have such problems but since the application is not critical, folks don't complain.
In a show situation as in CES demos, material can be carefully picked to avoid performance issues and of course yield is not a consideration as you can make enough to get what you need to show.
So personally I won't believe OLEDs are here until they actually show up, have ample supply, are priced reasonably, and have good performance. Yes, on measured contrast they should match or beat the Kuro. But the rest of the issues matter.
As you may know, Sharp licensed the trademark Elite from Pioneer and brought out a set of LCD TVs with very good performance. They are priced much higher though and from what I hear, sales are pretty slow. So longer term I am not sure they will continue selling them.
Thanks, Amir that was VERY informative.
It's true that the OLED hasn't seemed to be getting too much press since the last CES , I was wondering why
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