Originally Posted by flyers
I don't really know if all the LED's in the backpanel are all the same wattage or size, however, I would make the assumption that they are the same size wattage and color temp and only because there would be "hot spots" and a very non-uniform screen if they varied. I believe the "older" sets had few more likely because the more LED's you have the more complex the hardware and software needs to be. As technology gets better and cheaper it's easier to "add more" LEDs. Now, there is a point where there can be "too many" and that is probably the balance that they take into consideration during development.
Sony and Samsung didn't divulge how many LED's they have but I do know that Sony and the lone Sharp panel both use RGB LED lights rather than the cheaper white LED's. I'm not sure about the Sharp but the Sony used 2 green, 1 blue and 1 red LED. in each cluster and then they is put into zones. That is why the XBR 8 has unmatched flesh tones.
LG has stated they have 240 zones and almost 3,000 LED lights and yes this is double than the amount on last years LH90. Why, probably because of halo effect and better grey scale uniformity. But of course who really know why.
More dimming zones (accurately controlled by software!) = potentially
smaller halos (if controlled intelligently) and potentially
thinner sets (the gap between the LED and the panel doesn't need to be as large)
I believe the latter is the biggest advantage in the market and the companies will make sure that their new sets are thin as hell!
More LEDs = uniform picture (overlapping light cones of the LEDs) but higher wattage (this is why the Sony XBR8 uses more power than the Samsung A950, but still much less than a CCFL-LCD of the same size)
Now it gets more theoretical:
RGB-LEDs (regardless of the dimming capability) = potentially wider color gamut meaning "truer", "richer" colors (sadly no source material really makes use of that ATM). There are some potential PC applications (notebooks & monitors with RGB backlight are out now) but AFAIK
nobody supplies color profiles for TVs...
RGB-LEDs used as a white light source (no RGB dimming) = "better" white than pseudo-white LEDs, easier to tune with the color filter (the XBR8 is better out of the box) and longer life (when a white LED ages all colors are affected...)
RGB-LEDs used as RGB local dimming (only the Sharp XS1 at this time, *not* the XBR8) = Potentially better colors in dark areas, potentially even better colors - according to some reviews.
However, all reviews I have seen are from december 2008, january 2009 and they apparently tested a (pre/early-)release model of the XS1 which had a lot of bugs and/or missing features (no 100/120 Hz mode).
These reviews also critized some aspects about the picture and said that it is a bitch to calibrate (apparently the colored light of the BLU is difficult to tune with the color filter of the panel and the software/user interface isn't very helpful).
That being said I see a huge potential in this until OLED becomes the standard.