why don't lcd monitors use a colored(rgb led's) backlight and 1 pixel per pixel instead of using a rgb pixel triplet?

Use the backlight to get the color. Use the pixels for the brightness.
Unblock the light for the current pixel, while blocking the light on all the rest.

You would get 3x the resolution in the horizontal.

Can led's alter their brightness fast enough?

Wouldn't this just be the same thing?

short answer: certainly!
LCDs however, cannot.

there are DLP tv sets and projectors using this technique, because dlp chips have no lag at all. RGB leds can switch the backlight much faster than a color wheel, and they're a lot more efficient than a regular bulb.

with LCD however you'd have to wait for the pixel to switch to another color channel and THEN switch on the backlight. it's not impossible, but since 120hz panels seem to be the limit for Lcd as of now, you'd only get 40hz per full-color image, and that's just begging for dlp-style rainbows. The led dlps I've seen are 600hz, making rainbows a non-issue.

this exists long ago it's called OCB mode LCD
http://www.sidchapters.org/texas/TX_Cha ... ORI%29.pdf

yeah resolution can be triple as good , but profits might not.

I think I agree with AntiCatalyst. The main issue is the speed of the LCD. You would need quite low frequency updates to prevent bleeding of one colour into another. Also, the rainbow would be annoying. I have an old DLP that runs at 60Hz, and the rainbow effect on moving video is terrible, I'd rather a third resolution to that.

The thing is, what problem is this solving?

it'd make each pixel full-color instead of having an RGB triplet.

are triplets a problem? no.
DLP's benefit greatly from this though, since you get away with only one DLP mirror chip. they're very expensive

You have to recognise that standard white backlit LCD are hold type displays, white backlighting is turned on all the time, and if its not turned on that means brightness and hence contrast is lost forever while shuttering. Obsolete, and timeparallel won't really help imho.

Then you have to recognise CRT or POWERLED displays arent hold type displays, rather pulse type displays, this is why these work at much higher refresh and achieve much better contrast and brightness in a 3d with shutterglasses scenario.

...bet you guyys don't even know TMOS technology yet. That's a DLP alike too. But Its very similar to OCB afterall.

Well I just got an LED backlit LCD monitor. Quality looks decent to me. Colors look great, but the viewing angles are still the same as typical TFT LCDs.

that's because it IS a typical TFT LCD LED-TV is a big scam, there is NO difference in pq unless it's got full-matrix local dimming too, and that's basically only in high-end ones.

well at least they're a bit more energy efficient. and they can be made thinner(yay >.< )

also high power RGB Led can be pulsed, unlike low power white

OCB would be 40% efficient according to this, and 3DS is 2-3% efficient