Bring polarizing film
Palffy – Muhorray, “The Diverse World of Liquid Crystals”,
Physics Today, Sept. 2007
Some slides need re-organizing and tighter message.
1
LC = a misnomer.
These systems are not crystals….
and the study is not necessarily
confined to liquids either.
First related
observations:
Myelin
1700s –1850
2
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
3
4
5
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
6
classifications
Nematic smectic (a,c), chiral
Thermotropic, lyotropic
7
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.
8
http://farm1.static.flickr.com/57/220279395_26a24ae64f.jpg
9
Biaxial nematic
http://the2manadvantage.blogspot.com/2007/10/nhl-is-opening-flagship-store-in-nyc.html
http://www.thehockeyshop.com/hockey-sticks.htm
10
11
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.
12
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
13
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
14
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
15
Twisted nematic LC (Saupe 1969, KSU)
How to twist it?
How to switch it?
16
From PC World ~2000 (I think)
17
http://www.maxi-pedia.com/tft+lcd+display+monitor+panel
18
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
19
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.
20
Plasma….its days probably also numbered.
Probably better quality than LCD, though.
Plasma http://electronics.howstuffworks.com/plasma-display2.htm
21
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
22
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.
23
Even others can be considered.
Electronic paper Wiki
50 mm
Palfy-Muhorray review article
24