They aren't *that* slow. An LCD pixel can switch in single digit milliseconds. I've watched sports on 60 Hz TVs and on 120 Hz TVs and I can clearly see the difference when the ball is moving. On 60 Hz TVs the ball can almost disappear. I can't say if 240 Hz TVs are much better still.
-- Rick
Why do you think they don't use this method?
I will say I don't think they have any limitations with the LCD itself that limit the resolution. So I'm not sure this is a significant advantage.
-- Rick
Typo error. I meant 2 to 5 msec. Some detail from the above URL:
"In many cases two values are given for the response time of an LCD. The first is the black-white-black response time (the crystal rise time + fall time), and is the total time that it takes for one pixel to change from black to white and white to black. As of May 2010, the fastest class of LCDs have achieved high-speed response times of 1 ms or 2 ms."
"The other value is the middle gradation response time. It is the time that it takes a pixel to change from gray to gray (from one gradation of gray to another). An LCD has 256 gradations of gray, and in most cases several gradations are selected and the response time measured, and then the average value is taken as the middle gradation response time. LCDs with a fast middle gradation response time boast speeds of around 2 to 5 ms, and this is recorded in the specifications as "Gray-to-gray" or "G to G"."
Then, you don't need the mono LCD panel. Once you have an RGB LED per pixel, you have the equivalent density of an OLED display. No need for the monochrome attenuator to control color balance and color level, as those can be done by adjusting the current to each color LED.
I don't believe that this would produce 3x or 4x the dot resolution[1]. One color "dot" is produced by overlapping the colors from 3ea LED's. Therefore, the resolution would also be this combined color or the same as the LCD resolution. Well, strictly speaking, the
3 LED's are not on at the same time, but scan fast enough that your eye integrates the dot and it's 3 colors into desired RGB color making it look like one dot. If I arranged the LED patterns so that they do NOT overlap, then yes, I would see 3x or 4x the resolution. However, the picture would look like a rainbow or an old color CRT with a convergence problem. [1] a black LED?-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
How does that work if the frame/field rate is still 60/30 Hz?
Not sure what your model is. If you use the same LCD feature size as the current filtered LCDs, there will be 3 times as many pixels. Each pixel will produce the appropriate combination of the three colors. Not sure why you feel this isn't triple resolution. The only problem is I don't think this is a limiting feature on LCDs. They don't have any trouble producing full HD resolution on a 10 inch tablet. I know my laptop is full HD resolution.
-- Rick
There is a limitation but it's really one of contrast and brightness (smaller pixels decrease both). My cell phone is 1080p, too, but it doesn't have to light up a room, either (and doesn't work all that well in direct sunlight). I don't see any advantage to time-multiplexed RGB LEDs, though and several negatives (brightness, contrast, probably most importantly, refresh rate).
Multiple colors of LED display backlighting a monochrome LCD. If you can switch fast enough you get decent appearance with nice saturated colors without the pixelation in graphic displays (because the graphics is done once, on a computer, in extremely high resolution to lay out the segments and annunciators).
Would not work in an automotive environment- the displays are too sluggish on a cold day.
--sp
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