Linked by Hadrien Grasland on Sun 4th Sep 2011 12:39 UTC
Graphics, User Interfaces "Okay, it's been about one week and there are not much answers anymore, so it's time to thank everyone who participated, close this survey, and publish the results, along with some interpretation." Everything is released under Creative Commons CC0 license, so anyone interested, please help yourself.
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RE[2]: LED
by transputer_guy on Tue 6th Sep 2011 21:10 UTC in reply to "RE: LED"
transputer_guy
Member since:
2005-07-08

The Unipixel company in Texas had a TMOS panel based on a modified LCD LED structure. They replaced the LCD tricolor cell for a single Time Multiplexed Optical Switch and did RGB in time sequential mode. I had really great hopes for it since Samsung took a license in 09, but no word of it since.

Also they reported the classic LCD cell is less than 5% optically efficient so almost all the CFL or LED light source is turned into heat even for all white display. The TMOS cell is about 60% efficient so that would have been a huge power saver if it was used in tablets or laptops. Oh well, OLED might arrive one day.

Reply Parent Score: 2

RE[3]: LED
by Neolander on Wed 7th Sep 2011 07:14 in reply to "RE[2]: LED"
Neolander Member since:
2010-03-08

60% ? Impressive, I wonder how they achieve that. If they start from white light, isn't color filtering supposed to eat its share anyway, even if it's done sequentially ?

I mean, assuming that the Red, Green, Blue was a partition of the optical spectrum with equivalent energy to each color...
-When displaying red, green and blue have to be filtered out, so there go two thirds of the energy.
-When displaying green, red and blue have to be filtered out
-When displaying blue, red and green have to be filtered out

Or isn't it so ?

EDIT : Okay, according to this https://secure.wikimedia.org/wikipedia/en/wiki/Time-multiplexed_opti... , they don't start from white light, but have a light source that can intermittently emit red, green, and blue light instead.

How can such a source work ?

Edited 2011-09-07 07:21 UTC

Reply Parent Score: 1

RE[4]: LED
by transputer_guy on Wed 7th Sep 2011 14:40 in reply to "RE[3]: LED"
transputer_guy Member since:
2005-07-08

The TMOS cell is a very elegant but also simple design in principle (maybe not so in production). It uses the effect of two glass surfaces coming into contact, light bleeds easily and efficiently from one to the other, a technique that is also used by spies to tap into fiber optic cables, (in hidden closets perhaps).

The single light cell per pixel uses a capacitive MEMs device that pushes a clear top surface against the back plane surface or light substrate. Each MEMs cell actually has hundreds of redundant point contacts so no dead pixels. The back substrate has R,G,B LEDs along the side edges pulsed in time order. The color cycling can be done at very high frame rates so would be fully integrated by the eye. Since each pixel only uses 1 Fet, it can also be much smaller than the tri cell allowing very high pixel resolutions.

Unipixel ended up selling its substrate optical backplane patents to Rambus, this can also be used for flat LED lighting applications that are likely to be huge soon. Unipixel may have removed most of the interesting material from their website though.

Some of the ideas of TMOS are quite similar to the TI DLP. While TMOS is planar, DLP has to magnify & project the image on a CMOS MEMs chip to a screen or wall, just as efficient but not as desirable image quality and needs spinning prisms, color wheels, lamps, lenses, diffusers, Fresnel lenses etc. The images are still processed the same at the pixel level by pulse width modulation of the on off light switchs.

Funnily enough, Sony has a HD LED/LCD TV based on R,G,B,W cell that should be nearly twice as efficient as plain RGB. The idea here is that a 4th LCD cell in each pixel lets the majority of the White part of the pixel light through unfiltered. So if the RGB pixel value is 0x5080A0, then reduce that to 0x003050 and add 0x50 to white.

Reply Parent Score: 2