Searches on LCD: more efficiency with new technology
An article published in Nature Materials, the result of a joint research of the University of Milan and the University of Tokyo Japanese (Prof. H. Tanaka) and Kyoto (Prof. T. Araki) demonstrates a unique property resulting from the integration of materials solid and liquid: the "defect" in the arrangement of the molecules of the materials can be technologically exploited to reduce the energy consumption in the operation of the liquid crystal display.
Technological development has always gone hand in hand with the ability to integrate different types of material and nature.
A case of particular interest is when integrating solid and liquid materials, as in the case of the liquid crystal display. In this case, the geometry of the pixels and of the electric fields used to activate, take advantage of the symmetry and tendency to the order of the liquid crystal.
A study recently published in Nature Materials highlighted as well as the conflicts between the symmetries of the materials may be an element of great benefit in the construction of the display.
The research has studied what happens when a liquid crystal is inserted into the microcavities of porous solids of various types.
In many cases it produces a condition generally referred to as molecular frustration. In the recent research shows that the molecular frustration can become a virtue.
An example of frustration is shown in the photograph of the apse of the Rotonda di San Lorenzo in Mantua. The construction of an apse with bricks easily leads to a conflict on the order with which the bricks must be arranged.
The natural way to arrange the bricks is parallel to each other. If you build a wall floor, there is perfect harmony between the parallelism of the bricks and the shape of the wall. If, however, the structure that is constructed has a different symmetry, as in the figure, it creates a conflict that leads to the existence of a point where the bricks, instead of being arranged in parallel, are arranged radially.
In science this point where the bricks are not arranged in a natural way is indicated with the name of "topological defect".
This defect in the arrangement of bricks is analogous to what happens in the microscopic world when the liquid crystals (molecules that want to be arranged in parallel) are closed in the microcavity is a solid material.
In the case of liquid crystals, which occupy a volume instead of a surface such as bricks, topological defects are lines.
It shows an example of the bizarre paths that the topological defects (red lines) can form inside the porosity of a solid material (porosity regular cubical, in this case).
In these mixed structures is therefore produces an interesting situation: it starts with two materials and dial them is a third fundamental entity in order to understand and control the properties of the whole, the topological defects.
How are fundamental flaws you can understand returning the apse. The manufacturer could place the defect much higher or lower.
In these cases, the bricks would have been mostly horizontal (in the first case) or vertical (in the second).
If the bricks were liquid crystal molecules and if the apse was a pixel of the display, these two locations of defects correspond to pixels on and off pixels. So if the bricks were fluid and if the apse was a pixel, you could control his power on / off by changing the position of the defect.
If then there were two positions in the apse of the defect spontaneously stable, a top and a bottom, the pixel-apse may remain switched on or off without any forces should actively
keep the defect in its position. Serve some kind of force only to move the defect from one position to another.
In the research on liquid crystals enclosed in the pores is shown that there are indeed geometries in which topological defects can be stabilized in a few different positions. So once moved in one of these positions remain there, and with them remains switched on or off the pixels.
Therefore, research has shown that by controlling the defects that arise from the frustration of the liquid crystal, you can design devices that do not require power to maintain the pixels on (as it is now in the normal display), but require to act (with electric fields) just to move defects between the different stable positions. For example, to move to the position shown in the third image, that in the geometry shown, is stable.
This is a solution of interest for display devices of pages to read (books, newspapers, the so-called "digital books"), where speed counts of redefinition of the page, but the battery life.
The research is funded by the Italian, the foundation Cariplo. The group of State at the moment is already working, in collaboration with a group of Politecnico di Milano, for the experimental realization, through microfabrication of these structures.
20/04/2011
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Translated via software
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Source:
Italian version of ReteArchitetti.it