liquid crystal displays by farrell rogers materials research science and engineering center (mrsec)...
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Liquid Crystal DisplaysLiquid Crystal Displays
By
Farrell RogersMaterials Research Science and Engineering Center
(MRSEC)Interdisciplinary Education Group (IEG)
University of WisconsinMadison, Wisconsin
RET ProgramSummer 2006
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NanoScienceNanoScienceNanoscience involves the study and creation of materials,
devices, and systems through the manipulation of individual atoms and molecules.
o Describes research where the characteristic dimension of 1 or more plane is less than about 100 nanometers(.1 micron).
o Manufactured products are made from atoms. The properties of those products depend on how those atoms are arranged.
o If we rearrange the atoms in….o coal we get diamonds or graphite. o sand (adding a few other trace elements) we get computer
chips. o dirt, water and air we can make potatoes.
Unlike their larger or “macro” counterparts, nanoparticles often display unique properties that may be of use for various applications(Rattner & Rattner, 2003).
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States of MatterStates of Matter
Solid
Liquid crystal
“fourth state of matter”
Liquid
GasImages: MacDonald, R. “Liquid Crystals - Fascinating State of Matter or "Soft is beautiful". Accessed 7-2006
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Liquid Crystal – a stable phase of matter characterized by anisotropic properties without the existence of a 3-dimensional crystal lattice – generally lying between the solid and isotropic (“liquid”) phase.
What is a Liquid What is a Liquid Crystal?Crystal?
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IsotropicIsotropic
vs.vs.
AnisotropicAnisotropic
Liquids and gases(uniform properties in all
directions).
Liquid Crystals have orientational order
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There are 2 basic phases Nematic & Smectic
Anisotrpic substances may go through one or several
Liquid Crystal Phases
Liquid Crystal PhasesLiquid Crystal Phases
Images from Sheffield Hallum University, United Kingdom, 2006
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Liquid Crystal ModelLiquid Crystal Model
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Phase TransitionsPhase Transitions
Molecular Expressions, NHMFL-FSU( accessed, 2006.) http://micro.magnet.fsu.edu
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Project GoalsProject GoalsMy Curriculum Research Project focused
on Liquid Crystal Explaining Liquid Crystals Explaining Polarization Adapting the LCD Watch Dissection for my students
Designing a middle grade activity to create a simple LCD Panel
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Activity #1Activity #1Introducing Liquid CrystalsIntroducing Liquid Crystals
After reading a brief history and description of Liquid Crystals, students will answer some questions and use drawings to compare the 4 states of matter.
I designed a questionaire for this activity.
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Activity #1Activity #1Comparing Liquid CrystalsComparing Liquid Crystals
Part II: Visualizing Liquid Crystals 1-In the box below draw how the molecules of each
of the following phases might be arranged if you could see them.
Solid Phase LC Phase Liquid Gas
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Activity #2Activity #2Part 1: Polarized LightPart 1: Polarized Light
This activity involved having kids explore the properties of light using 2 polarized lenses. They will compare light from an CRT TV, LCD Screen and from an incandescent bulb.
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Activity #1 PicsActivity #1 Pics
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Activity #2Activity #2Part 2: “To Twist or Not to Part 2: “To Twist or Not to
Twist, a Play of Polarization”Twist, a Play of Polarization”
This is a student run Demo where different kids play different roles to demonstrate the parts of a Liquid Crystal Display.
Image: How Stuff Works, 2006
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Activity #3Activity #3
Adapting the LCD Watch Dissection
MRSEC/IEG already has an excellent lab for this at http://mrsec.wisc.edu/Edetc/nanolab/watch/index.html
The only thing I would add would be testing to see if Dry Ice was cold enough to solidify the LC and prevent the LCD Panel from Functioning. (Maybe Next Year? Please :o)
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Activity #4Activity #4Making a Liquid Crystal Making a Liquid Crystal
DisplayDisplayEverything seems easier once you figure it out.
I had a few obstacles such as… Which LC, How much LC, How thick the spacers should be, How much voltage, Do I need an orientational polymer, How do I apply the chemicals, etc.
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MaterialsMaterials5CB Liquid Crystal
ITO Conducting Glass slides
Polyvinyl Alcohol
Polarized Lenses
Capillary tube Pipettes
Binder Clamps
9V Battery
Glass Petri dishes
Hot Plate
Alligator clamps
Copper wire
Saran Wrap
Cotton Cloth
Tweezers
Q-tips
eyedropper
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LCD AlignmentLCD Alignment
When coming into contact with a finely grooved surface (alignment layer), LC molecules line up parallel along groove due to their rod-like shape.
Coating ITO glass with a layer of PVA and rubbing repeatedly creates these grooves.
Sharp Technologies, Inc. 2006
Natural state
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LCD OrientationLCD Orientation
The molecules along the upper plate point in direction 'a' and those along the lower plate in direction 'b,' thus forcing the liquid crystals into a twisted structural arrangement./ (figure shows a 90-degree twist) (TN type liquid crystal)
Sharp Technologies, Inc. 2006
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Unique Properties of Liquid Unique Properties of Liquid CrystalsCrystals
The orientation of Liquid Crystals can be affected by…
PressureTemperatureElectrical Field
S. Palmer, LCTec Displays, Inc. 2005
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LCD PreparationLCD Preparation
Checking the ITO Glass
Rubbing the PVA to create an alignment
layer
Removing the PVA at one edge
Placing the Saran Wrap Spacers
Applying the Liquid Crystal
Placing the Polarizers at 90°
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The LCD SandwichThe LCD Sandwich
Modified from S. Palmer, LCTec Displays, Inc. 2005
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LCD TechnologyLCD Technology
Electrical-field
NOT Applied
Light IS transmitted
Electrical-field
IS Applied
Light NOT transmitted
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LCD ResultsLCD Results
Electrical-field NOT Applied
Light IS transmitted
Electrical-field IS Applied
Light NOT transmitted
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LCD In ActionLCD In Action
pics\LCD13.mov
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LCD ApplicationsLCD Applications
The Nematic phase is most commonly The Nematic phase is most commonly used in Liquid Crystal Displays used in Liquid Crystal Displays
(LCD)(LCD)
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Prior Knowledge Prior Knowledge and Timingand Timing
LC’s can be discussed during any of the following units:
– States of Matter/Phase Changes– Properties of Light– Electricity
Possibly make it a long term activity discussing what an LC is during Matter, then doing the Watch Dissection & LCD Fabrication during the other Units?
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Standards AddressedStandards AddressedScience Nature of Science
History of Science Variables and Experimentation
Chemistry Matter
Physical Science Waves Energy Electricity
Technology & Society
Language Arts Main Idea Using Context Clues
These activities would be appropriate for Science students in grades 8-12.
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ReferencesReferencesReferences:1-Rudy, Lisa Jo. “Between the Boundaries of the Known
The Molecular World between Solid and Liquid”. Copyright ©2004 University of Pennsylvania. School of Arts and Sciences Updated September 1, 2004.http://www.sas.upenn.edu/sasalum/newsltr/spring04/between_boundries.htmlAccesses 6-25-20062-How Stuff Works. Building Your Own LCD. July 2006.http://electronics.howstuffworks.com/lcd4.htmAccesses 6-25-20063- The University of Wisconsin. Materials Research Science and Engineering Center (MRSEC)-Interdisciplinary Education Group (IEG)Engineering Centers Buildinghttp://mrsec.wisc.edu/Edetc/nanolab/index.htmlAccesses 6-25-20064-Ratner, M. & Ratner, D. Nanotechnology, A Gentle Introduction to the Next Big Idea, 2003. Pearson Education, Inc.5- Kent State University. Liquid Crystal Institute,http://www.lci.kent.edu/Accessed 7-6-20066- Macdonald, R., “Liquid Crystals - Fascinating State of Matter or "Soft is beautiful". Optical Institute of the Technical University of Berlin
Straße des 17. Juni 135, 10623 Berlin, GermanyAccessed 7-6-20067-Touch Screen infohttp://www.reedlink.com/ProductInfo~Productid~142231~ProductName~Touch-Screen-Displays.htmlAccesses 7-6-20068-Universität Hamburg Liquid Crystal Databasehttp://liqcryst.chemie.uni-hamburg.de/lcionline/liqcryst/lchistory/topics/c13b5.htmlAccesses 7-6-20069-Waclawik, Eric R. “Liquid-Crystal Displays: Fabrication and Measurement of a Twisted Nemetic Liquid Crystal Cell”. Journal of Chem. Engineering 81, no.
6, (2004) 854-858.10-Ondris-Crawford, R., Crawford, G.P., and Doane, J.W. “Liquid-Crystals, Phases of the Future”. The Physics Teacher 30, Sept. (2004) 332-339.11-Sadlej-Sosnowska, Nina. “Imposed Orientation of Dye Molecules by Liquid Crystals and an Electric Field”. Journal of Chem. Ed. 57, no. 3 (1980) 223-224.12-Daigle, Stephen M.. “Investigating the Bistibility of 4’-octyl-4-Biphenylcarbonitrile”. Liquid Crystal Institute, Kent State University (July 2004).http://clcse.lci.kent.edu/students.htmAccesses 7-12-200613- Sharp Technologies, Inc1. The Principles of LCD Technologyhttp://sharp-world.com/sc/library/lcd_e/s2_1_1e.htmAccesses 7-12-2006
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Thank youThank you Wendy Crone, Ph.D.: MRSEC Director of Education, University of Wisconsin Greta Zenner, Ph.D.: MRSEC Assistant Director of Education, University of
Wisconsin MRSEC-RET program Dana Horoszewski , Ph.D.: IEG Mentor Ken Gentry, Ph.D.: IEG Mentor Dr. George Lisensky, Ph.D.: IEG Mentor, Professor of Chemistry, Beloit College University of Wisconsin NSF, Research Experiences for Teachers(RET Programs)
"We are grateful to the National Science Foundation through the Materials Research Science and
Engineering Center (MRSEC) on Nanostructured Interfaces (DMR-0079983 and DMR-0520527) at the
University of Wisconsin-Madison”