Transcript Palffy muhorray - Louisiana State University

Bring polarizing film
Palffy – Muhorray, “The Diverse World of Liquid Crystals”,
Physics Today, Sept. 2007
Some slides need re-organizing and tighter message.
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LC = a misnomer.
These systems are not crystals….
and the study is not necessarily
confined to liquids either.
First related
observations:
Myelin
1700s –1850
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Discovery is usually associated with the
behavior of cholesteryl benzoate, which
by ~1888 was known to have two
melting points.
Discovery due to Reinitzer & Lehman = Botanist & Physicist
Note the rather extended shape!
Irridescent beetle colors may
Trace to “liquid” “crystal”
behavior. (from a beetle wiki)
See also Srinivasarao Science 2009
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1949 Onsager f > 4/x (x = L/d) kind of a pure
packing argument, logs in a river photo.
1959 Maier Saupe extend to temperature;
anisotropic polarizability below some crit
temperature
1965 Kent State Glenn Brown
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classifications
Nematic smectic (a,c), chiral
Thermotropic, lyotropic
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http://www.texasbeyondhistory.net/timberhill/images/greatraft.html
The "Great Raft," a huge mass of timber that formed a logjam, dammed up the
Red River and flooded the surrounding area. Photo by R. B. Taylor, courtesy
Louisiana State University, Shreveport, Noel Memorial Library Archives.
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http://farm1.static.flickr.com/57/220279395_26a24ae64f.jpg
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Biaxial nematic
http://the2manadvantage.blogspot.com/2007/10/nhl-is-opening-flagship-store-in-nyc.html
http://www.thehockeyshop.com/hockey-sticks.htm
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LC’s as displays. Why do we need
something besides the CRT?
Vacuum! How heavy does a CRT have to be to be strong enough
to maintain vacuum, since the e-beam has to travel from gun
to phosphor screen? This is a fundamental limitation.
The problem is CRTs have a heart of glass!
By contrast, the limiting size of LCD’s = production yields of large,
defect-free films. There is no fundamental limitation, merely a
matter of engineering.
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Even so, very huge LCD displays are not with us yet; we use projection. For now.
Casio Hybrid Projector
Actually, this isn’t an LCD display.
Doesn’t use a lamp either….
$800 gets you a “hybrid” light source
with DLP technology.
Animated GIF of how it works.
LG HS201 Slim
Sort of 6” x 6” size
Not an LCD
No lamp
$550
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DIY LCD Projector Videos
Heart of Glass doesn’t cut it in the plastics world:
http://www.youtube.com/watch?v=FKrKHtdXroo
OHP
http://www.youtube.com/watch?v=NWlsPfPZTdc
Cracker box:
http://www.youtube.com/watch#!v=KZ_KpQV
1Vmo&feature=related
http://www.youtube.com/watch?v=n6n6jW0XIV0&featur
e=related DIY LCD Projector >500000 views
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The idea of using LCs for light display goes back to
simple rubbing of glass experiments.
1911 It is found that rubbing glass can align the LC molecules; crossed rubbing
leads to no transmission of light through the objects.
1922 word mesomorphic coined
1935 Freedericksz finds E field can align LCs
1936 patent (British) to Marconi for “light valves….for use in
television, facsimile telegraph and other systems”
Postwar: synthesis of mesogens
By 1950s, a thriving subject
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Twisted nematic LC (Saupe 1969, KSU)
How to twist it?
How to switch it?
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From PC World ~2000 (I think)
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http://www.maxi-pedia.com/tft+lcd+display+monitor+panel
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The invention of the TFT made this
practical in large arrays.
The TFT was invented
in 1973 by Westinghouse
(120 x 120 pixels in 6” x 6”
array = 0.05”/pixel).
By this time, the USA had
already ceded other video
technology, such as video
tape recording, to the
Japanese.
TFT/LCD panels met the
same fate.
http://en.wikipedia.org/wiki/TFT_LCD
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There are opportunities for polymers in this game.
About 40% of Corning’s $4.6B revenues in 2006 came from LCD glass.
So…how do you make a perfectly flat, bubble-free piece of glass?
Plastics’ role: under 30” the sandwich can be made from plastic.
From some website: The liquid crystal is placed between the two sheets in a
patterned plastic sheet that divides the liquid into individual shutters and
keeps the sheets at a precise distance from each other.
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Plasma….its days probably also numbered.
Probably better quality than LCD, though.
Plasma http://electronics.howstuffworks.com/plasma-display2.htm
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Research continues. This Fabry-Perot interferometer
device requires poly(ethylene napthalate) which
deflects to create a light gate at a particular color.
http://spie.org/x8775.xml?ArticleID=x8775
PEN, even better barrier
properties than PET
This color display is
flexible!
Harry Potter-Style Newspapers a Reality
http://www.dailymail.co.uk/news/worldnews/
article-1207944/Harry-Potter-meets-MinorityReport-video-adverts-magazines-reality.html
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The future is probably with these
technologies: OLED FED SED
The LCD is limited by energy cost—tosses away an
awful lot of light; 40” display about 250 W, same
as CRT.
Organic LEDs will light up just where/when you
need.
FED/SED display = array of nanotubes that makes
electrons for phosphors just where/when you
need them.
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Even others can be considered.
Electronic paper Wiki
50 mm
Palfy-Muhorray review article
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