[opendtv] Re.Swiss develop full spectrum colour display technology

 
 
Does anyone have any more knowledge of this? From the BBC News website...
 
Nick Radlo
.............................
 
Artificial muscles light up TVs 
 
By Jonathan Fildes 
Science and technology reporter, BBC News 
 
Arrays of thousands of tiny "super prisms" controlled by robotic muscles could 
bring real colour to TV screens for the first time, scientists say. 
 
The devices, known as electrically tunable diffraction gratings, have been 
built by researchers in Switzerland. 
 
They manipulate light to reproduce the full spectrum of colours on screen, 
impossible using existing technology. 
 
The team say the devices could also be used to make computer displays with the 
same resolution as high-end LCDs. 
 
"Today's displays can only reproduce a limited range of colours," said Manuel 
Aschwanden of the Swiss Federal Institute of Technology in Zurich, and one of 
the team behind the work. 
 
"The main advantage of this technology is that it can display all colours." 
 
Existing screen technology, like TV cathode ray tubes, LCDs and plasma screens, 
reproduce colours using three lighting elements coloured red, green and blue. 
 
Other colours are created by combining the primary colours. For example, yellow 
is created by mixing red and green. 
 
To show complex pictures a display must combine the colours at thousands of 
individual points across the screen.
 
Different types of screen do this in different ways. For example an LCD is 
divided into thousands of individual pixels, further divided into three 
subpixels coloured red, green, and blue by filters. 
 
Altering the brightness of each coloured subpixel creates a palette of millions 
of different shades that can be used to represent most pictures. 
 
Methods like this are unable to reproduce every colour we see in the real 
world. This is particularly evident when reproducing images of the sky. 
 
"When you take a picture and download it to your laptop the blues are never the 
same as the real sky," said Mr Aschwanden. 
 
Problems like this occur because the three primary colours current displays use 
to reproduce on-screen colour are fixed. The green, blue and red a manufacturer 
chooses to use in a display determine all the other colours it can reproduce. 
 
The new system is not limited to the three colour system. 
 
Instead, the researchers have developed a flexible approach that uses the full 
spectrum of colours visible to the naked eye. 
 
To do this the team have built what they call a diffraction grating, a slotted 
grate like a miniature Venetian blind. 
 
Diffraction grates are nothing new. They are already used in projector systems 
and fibre optic telecommunications. 
 
However, unlike existing solid grates the new one is made of a flexible 
polymer. 
 
The rubbery material is normally used to build artificial muscles for robots as 
it contracts if a voltage is applied. 
 
When pure white light from a light emitting diode (LED) hits the grate it is 
split into the full spectrum of colours like a rainbow produced by a prism. 
 
By applying different voltages to the artificial muscle the grate expands and 
contracts, causing the fan of split light to shift from side to side. 
 
Different colours can then be isolated from the spectrum using a tiny hole 
fixed in front of the grate. Adjusting the voltage across the muscle allows 
different parts of the colour spectrum to be lined up with the hole. 
 
In a working screen, multiple grates behind each pixel would also allow 
composite colours to be mixed, reproducing the full range of colours the human 
eye can perceive. 
 
At the moment the team have built a proof-of-concept array of 400 gratings side 
by side. Although too small to be useful the miniature display has a high 
resolution. 
 
"It is the same density as a high-quality LCD display," Mr Aschwanden told the 
BBC news website. 
 
The team are now working on refining their experimental setup and in particular 
trying to lower the voltage required to make the system work. 
 
Initial experiments required thousands of volts to flex the muscle, but the 
team have now reduced that to 300, making the technology more attractive to 
electronics firms. 
 
With more refinement Mr Aschwanden says that the devices could have multiple 
uses in microscopes, fibre optic communications as well as high-end colour 
screens. 
 
"Tuning or steering light is at the core of all optical systems", he said. 
"This offers a cheap, accurate way to do it." 
 
The work was carried out with Professor Andreas Stemmer at the Swiss Federal 
Institute of Technology and is published in the US journal Optics Letters. 
 
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/technology/5263108.stm
 
Published: 2006/08/21 07:49:00 GMT

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