FOURTH WAVE IN DISPLAYS

From: Dr. Jai Maharaj (usenet_at_mantra.com)
Date: 07/25/04 

Date: Sun, 25 Jul 2004 22:12:06 GMT

Fourth wave in displays

Brighter, lighter, monitors; giant TV screens that you
can roll up; see-through walls; wallet photos that move.
Anand Parthasarathy looks at the technology that makes
these possible.

The Hindu
Thursday, July 22, 2004
 
Inkjet process was used to deposit the organic layers
during fabrication of the world's largest OLED-based
displayed screen.

FIRST THERE was the Cathode Ray Tube or CRT -- still the
technology behind the vast majority of computer monitors
and television screens. Streams of electrons are
accelerated by high voltage anodes, formed into three
coloured beams by focusing electrodes and projected on a
phosphorescent screen where they fuse to create the
moving picture.

Then came the Liquid Crystal Display or LCD: Two sheets
of polarising material with a liquid crystal solution
between them. An electric current passed through the
liquid causes the crystals to align so that light cannot
pass through them.

Each crystal, therefore, is like a shutter, either
allowing light to pass through or blocking the light. For
intense colour, LCD displays use what are known as Thin
Film Transistors (TFT), where each sub-pixel or coloured
dot in the display has its own active controlling
transistor.

With the coming of home theatre systems, customers
demanded larger and brighter screens up to 60 inches
diagonally. The need was met by the Plasma display, an
emissive flat panel, where light is created by phosphors
excited by a plasma discharge between two flat panels of
glass. Plasma displays use twice as much power as a
comparable CRT television and were much heavier than the
LCD screens.

None of these three technologies was perfect or easily
scalable. Which is why the imaging industry in recent
months is frantically dusting a technology that two
scientists at Kodak first demonstrated in 1987:
generating light with certain organic crystals, which had
the property of electroluminescence. In other words, they
brightened when excited by a jolt of electricity. However
the very high excitation voltage requiring more than 100
volts -- inhibited commercial development for many years.
Today it has morphed into the Organic Light Emitting
Diode (OLED) -- an electronic device made by placing a
series of organic thin films between two conductors.

When electrical current is applied, a bright light is
emitted. OLED technology produces self-luminous displays
that, unlike LCDs, do not require backlighting. These
properties result in thin, very compact displays. The
displays also have a wide viewing angle, up to 160
degrees and require very little power: between 2 and 10
volts.

Like LCDs, OLEDS come in both passive and active types.
Passive-matrix displays are created by depositing the
electrode material in a matrix of rows and columns, the
OLED being formed at the intersection of a row and a
column. The video image is obtained by rapid scanning
through all rows and columns in about 1/60 of a second.
Active matrix displays use thin film transistor (TFT)
technology, with each OLED controlled by two transistors.
For this reason the light output of each pixel is
controlled continuously, instead of being pulsed once
every refresh cycle, leading to brighter, sharper
pictures.

While many companies have achieved prototypes of OLED
displays, marketable products have come in fairly small
sizes. Kodak and Sanyo produced the world's first active
OLED displays for a digital camera -- the Kodak EasyShare
LS633 -- last year, using 2.2 inch screens. Samsung and
NEC are using the Kodak technology for passive OLED
mobile phone displays.

But large home theatre-sized TV displays remained
difficult to realize in OLED, inspite of the promise of
drastically improved viewing experience. All that changed
in May this year, when the Japan-based Seiko Epson,
unveiled the world's largest OLED display to date -- a 40-
inch OLED TV.

The major technical challenge was in forming the organic
layers on large sized TFT substrates. It was perhaps
logical that a company better known for its range of
inkjet printers should be the first to realize a large
format OLED display. Its patented `micro piezo'
technology of inkjet printing came in handy to `print'
the OLED display elements on to the TFT by delivering the
droplets to the precise position in the matrix and then
applying a drying solvent. The beauty of this method is
that OLED displays can now be essentially mass-produced
and `printed' on a variety of substrates including
plastic.

This opens the exciting possibility that if the plastic
is flexible, one can, in theory, create TV screens that
can be rolled up and carried away or hung on the wall
like a picture. Indeed this is just one of the ideas that
Epson's engineers are working on.

Other way-out ideas include `moving pictures' -- that
wallet photo of your family could well be a television-
like micro-chunk of video. And entire walls can be fitted
with ultra thin displays, much as one would affix
wallpaper. A few cameras strategically placed, could then
capture the scene outside and beam it on the wall to
provide the illusion that the wall had suddenly become
`see through'.

Bizarre? Perhaps, yes but clearly achievable, given the
current road map of OLED. Epson is one of a handful of
companies, which are racing to convert that large screen
prototype into a mass-market TV product by 2007. The date
has its logic; it will be nicely timed to ride the
expected surge in television business before the 2008
Beijing Olympics. And even as the world prepares for this
year's Olympic Games, hundreds of scientists in dozens of
imaging companies are already looking four years ahead,
in quest of their own version of Citius, Altius, Fortius
 -- faster, higher, stronger ... or as they like to say in
the display business: thinner, brighter, lighter.

More at:
http://www.hindu.com/seta/2004/07/22/stories/2004072200441600.htm

Jai Maharaj
http://www.mantra.com/jai
Om Shanti

Hindu Holocaust Museum
http://www.mantra.com/holocaust

Hindu life, principles, spirituality and philosophy
http://www.hindu.org
http://www.hindunet.org

The truth about Islam and Muslims
http://www.flex.com/~jai/satyamevajayate

The terrorist mission of Jesus stated in the Christian bible:

     "Think not that I am come to send peace on earth:
I came not so send peace, but a sword.
     "For I am come to set a man at variance against his
father, and the daughter against her mother, and the
daughter in law against her mother in law.
     "And a man's foes shall be they of his own
household.
 - Matthew 10:34-36.

     o Not for commercial use. Solely to be fairly used for the
educational purposes of research and open discussion. The contents of
this post may not have been authored by, and do not necessarily represent
the opinion of the poster. The contents are protected by copyright law
and the exemption for fair use of copyrighted works.
     o If you send private e-mail to me, it will likely not be read,
considered or answered if it does not contain your full legal name,
current e-mail and postal addresses, and live-voice telephone number.
     o Posted for information and discussion. Views expressed by others
are not necessarily those of the poster.