Something interesting from New Scientist, maybe overkill for existing video
frame sizes, but certainly nice for stills...
New display 'as clear as a glossy magazine'
The prototype still-image display unveiled at London's National Gallery this
week looked far from ready for the high street, but Hewlett-Packard is
confident that the revolutionary liquid-crystal display technology it has
developed will ultimately lead to ultra high-resolution flat screens ranging
in size from a magazine page to an advertising billboard. What is more, they
will use far less power than ordinary LCD screens, and can be made using
cheap printing technology.
Giant TV screens that hang on the wall have already escaped from the lab,
and electronic displays have appeared as small e-book screens, but they
cannot match the resolution of the colour printing process used in magazines
and books.
Conventional computer screens can only manage 1600 by 1200 pixels, and even
high-definition TV displays create their images with an array of 1920 by
1080 pixels at best. Now, HP reckons it can make an A4-sized screen with
7000 by 5000 pixels - matching the quality of a glossy magazine. HP says it
will be able to replicate this quality on screens all the way up to large
electronic posters and billboards.
In a standard LCD cell, layers of liquid crystals are sandwiched between two
polarising filters. Normally, successive layers of liquid crystals are
twisted in a way that rotates the polarised light passing through by 90
degrees.
But apply an electric field across the cell and the crystals line up so that
they no longer rotate the light, and the cell switches on. To keep the pixel
on or off, a transistor has to supply a "refresh" current 50 or 60 times per
second. This transistor is costly, and the refreshing process consumes
power.
Polymer posts
HP's new screen is different. It relies on a curious discovery made by its
engineers. When liquid crystals are put in contact with polymer "posts"
smaller than a micrometre across (see graphic), the rod-like liquid crystals
naturally align around the post in one of two directions: horizontally, or
tilted upward in a spiral around the post.
Applying an electric field switches their position from horizontal (a dark
pixel) to tilted (a lit pixel). Crucially, both states are stable, so when
the field is removed the liquid crystals stay where they are. This means the
screen draws no power once an image is displayed.
HP calls the new system a post aligned bistable nematic (PABN) LCD. To make
it, a printing plate covered with an array of sub-micrometre pits is smeared
with a clear polymer ink and stamped onto a transparent sheet of
polycarbonate plastic, creating a forest of polymer posts.
The sheet is overprinted with red, green and blue filters and thin metal
electrodes. A second transparent sheet is printed with electrodes, and a
liquid-crystal material is sandwiched between the two.
The crystals cling to the posts and the electrodes supply the electric field
that flips the crystals. Several thousand posts fit in the area of a
traditional LCD pixel, giving the display its very high resolution.
At this week's London launch, HP showed two 4 by 3-centimetre prototypes.
One was continually refreshed with new colour images to show how the display
can be changed about once a second, as would be expected when turning the
pages of an e-magazine. The other display had power only to supply the
backlight. The last image it had received was frozen on screen with no power
needed to maintain it.
The images on the prototypes were undeniably coarse, with visible blemishes
and faulty pixels. But HP stressed that PABN will not be ready for market
any time soon. Rather, the demonstration is proof that the technology works.
Adrian Geisow, manager of display research at HP's labs in Bristol, UK, says
screens the size of an open magazine spread should be possible within five
years.
"Power consumption will depend on how quickly you 'turn' the pages," he
says. Geisow estimates that the cost of making the PABN-based screens will
be one-fifth that of today's LCD flat screens. The speed at which the posts
change state is expected to improve, so a video-capable version has not been
ruled out.
Cheers, Jason (remove ... to reply)
Video & Gaming:
http://gadgetaus.com
Similar Threads
