scholarly journals Security devices based on liquid crystals doped with a colour dye

2011 ◽  
Vol 19 (4) ◽  
Author(s):  
C. Carrasco-Vela ◽  
X. Quintana ◽  
E. Otón ◽  
M. Geday ◽  
J. Otón
Keyword(s):  
Liquid Crystal ◽  
Polarized Light ◽  
Dielectric Surface ◽  
The Other ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Alignment Layer ◽  
Multiple Images ◽  
Crystal Properties ◽  
Twist Structure

AbstractLiquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices.Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multiple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC cell. By rubbing the polyimide in different directions in each substrate it is possible to create any kind of symbols, drawings or motifs with a greyscale; the more complex the created device is, the more difficult is to fake it.To identify the motifs it is necessary to use polarized light. Depending on whether the polarizer is located in front of the LC cell or behind it, different motifs from one or the other substrate are shown. The effect arises from the dopant colour dye added to the liquid crystal, the induced orientation and the twist structure. In practice, a grazing reflection on a dielectric surface is polarized enough to see the effect. Any LC flat panel display can obviously be used as backlight as well.

Market adjacency and competing technologies: evidence from the flat panel display industry

2019 ◽  
Vol 28 (6) ◽  
pp. 1429-1447
Author(s):  
Derek Lehmberg ◽  
Charles Dhanaraj ◽  
Rod White
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystal Display ◽  
Cost Advantage ◽  
Flat Panel Display ◽  
Plasma Display Panel ◽  
Flat Panel ◽  
End Products ◽  
Plasma Display ◽  
The Cost ◽  
Competing Technologies

Abstract What determines the emergence of a winner between competing technologies? We examine competition between flat panel display technologies, with the purpose of understanding of how liquid crystal display was able to surpass plasma display panel technology despite the initial lack of a convincing technological or cost advantage, and in the absence of network externalities. We propose an explanation whereby the relative availability of pathways of suitable adjacent applications markets provides differential opportunities for technologies to increase their scope and scale of application incrementally, effecting the speed of development as well as the cost effectiveness of the end products. Our findings suggest that these sets of adjacent application markets available can strongly influence which technologies emerge as winners and which are eventually abandoned.

A Flat Panel Display Combining a Polymer-Dispersed Liquid Crystal Film with an Electroluminescent Device

1994 ◽  
Vol 33 (Part 2, No. 6B) ◽  
pp. L870-L872 ◽  
Author(s):  
Andy Ying-Guey Fuh ◽  
Chi-Yen Huang ◽  
Chi-Ren Sheu ◽  
Gen-Lan Lin ◽  
Ming-Shann Tsai
Keyword(s):  
Liquid Crystal ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Electroluminescent Device ◽  
Polymer Dispersed Liquid Crystal ◽  
Crystal Film ◽  
Polymer Dispersed

scholarly journals The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

2020 ◽  
Vol 16 ◽  
pp. 175-184 ◽  
Author(s):  
Itamar L Gonçalves ◽  
Rafaela R da Rosa ◽  
Vera L Eifler-Lima ◽  
Aloir A Merlo
Keyword(s):  
Liquid Crystal ◽  
Relative Position ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Ammonium Thiocyanate ◽  
The Other ◽  
Amide Derivatives ◽  
Crystal Properties ◽  
Benzoyl Chlorides ◽  
Membered Heterocycle

A series of novel thiourea and amide liquid crystals containing 5-membered isoxazoline and isoxazole rings were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material. Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered heterocycle.

Integral-Color Plastic Liquid Crystal Display The Ultimate Flat Panel Display

1999 ◽  
Vol 30 (1) ◽  
pp. 1054 ◽  
Author(s):  
Carl Chiulli ◽  
Joseph DelPico ◽  
William Vetterling ◽  
Kristina M. Johnson ◽  
Gary D. Sharp ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystal Display ◽  
Flat Panel Display ◽  
Flat Panel

Bistable Technology in Flat Panel Display: Principle and Progress

2010 ◽  
Vol 428-429 ◽  
pp. 206-211 ◽  
Author(s):  
Zi Qiang Huang
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Thin Film Transistor ◽  
Manufacturing Cost ◽  
High Grade ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Display Devices ◽  
Light Interference

Active matrices often related with high grade display devices, due to application of the storage elements, typically thin film transistor (TFT). Because of the complex procedures in the manufacturing TFT, investment of the high value manufacturing equipments and clarification plants is necessary, hence increasing the manufacturing cost of the flat panel, and more importantly, causing the pollution of water and air. As the contribution of TFT array merely exists in supplying storage function for the pixels of the display panel, large efforts have been made to find suitable cells that have bistable effect, so as to substitute the effect of TFT. As the bistable cell is just the storage pixel, one could construct a bistable cell to skip the needs of TFT active matrices. The paper is to introduce currently available bistable display devices in the following field: liquid crystal bistable displays with cholesteric liquid crystals, which is an example to introduce the bistable technology; iMod display devices based on mechanic induced bistable and light interference, which shows the possibility to construct bistable display; and the display based on solid powder movement in air or in vacuum, so called liquid powder displays, which shows how to improve the existed display.

scholarly journals Chromosome Malorientations after Meiosis II Arrest Cause Nondisjunction

2007 ◽  
Vol 18 (5) ◽  
pp. 1645-1656 ◽  
Author(s):  
Marie A. Janicke ◽  
Loren Lasko ◽  
Rudolf Oldenbourg ◽  
James R. LaFountain
Keyword(s):  
Liquid Crystal ◽  
Light Microscope ◽  
Daughter Nucleus ◽  
Polarized Light ◽  
Live Cell ◽  
The Other ◽  
Sister Kinetochore ◽  
Microscope Imaging ◽  
Birefringent Fiber ◽  
Spindle Elongation

This study investigated the basis of meiosis II nondisjunction. Cold arrest induced a fraction of meiosis II crane fly spermatocytes to form (n + 1) and (n − 1) daughters during recovery. Live-cell liquid crystal polarized light microscope imaging showed nondisjunction was caused by chromosome malorientation. Whereas amphitely (sister kinetochore fibers to opposite poles) is normal, cold recovery induced anaphase syntely (sister fibers to the same pole) and merotely (fibers to both poles from 1 kinetochore). Maloriented chromosomes had stable metaphase positions near the equator or between the equator and a pole. Syntelics were at the spindle periphery at metaphase; their sisters disconnected at anaphase and moved all the way to a centrosome, as their strongly birefringent kinetochore fibers shortened. The kinetochore fibers of merotelics shortened little if any during anaphase, making anaphase lag common. If one fiber of a merotelic was more birefringent than the other, the less birefringent fiber lengthened with anaphase spindle elongation, often permitting inclusion of merotelics in a daughter nucleus. Meroamphitely (near amphitely but with some merotely) caused sisters to move in opposite directions. In contrast, syntely and merosyntely (near syntely but with some merotely) resulted in nondisjunction. Anaphase malorientations were more frequent after longer arrests, with particularly long arrests required to induce syntely and merosyntely.

Polymer-Dispersed Liquid Crystals: Boojums at Work

MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 22-28 ◽  
Author(s):  
J. William Doane
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Polarized Light ◽  
Solid Particles ◽  
Water Soluble ◽  
The Other ◽  
Polymer Materials ◽  
Water Soluble Polymer ◽  
Polymer Dispersed

The idea of dispersing micron-size birefringent particles in a polymer to selectively scatter light is not new. In the 1930s Land patented a light polarizing material in which small, oriented solid crystallites were suspended in a clear polymer. The polymer material was selected so that its refractive index matched one of the principal refractive indices of the crystallites while the other did not. The resuit was a light polarizer tha t would pass one component of polarized light but scatter the other component out of the beam path.This idea was substantially expanded by the introduction of liquid crystals as the birefringent material. The orientation of the particles (in this case droplets), and hence the refractive index match and the scattering, could be controlled by an electric field. Such a material could be used as a light shutter for either unpolarized or polarized light. In the mid-1970s this basic concept was applied by Hilsum, but having no way to disperse droplets of liquid crystals in a polymer, he did the opposite and put optically isotropic solid particles in the birefringent liquid crystal.Although Hilsum demonstrated the concept, no commercial device was produced, probably because the shutter contrast was limited. Since then several ways have been found to disperse droplets in a polymer: filling the pores of a microfilter; emulsifying the liquid crystal in a water soluble polymer; and using phase separation methods to create a dispersion of droplets in non-aqueous polymer materials.

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