Do Liquid Crystals maintain position?

Discussion in 'General Electronics Chat' started by patthehat033, Oct 6, 2016.

  1. patthehat033

    Thread Starter New Member

    Jul 28, 2012
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    Hello,

    I know that Liquid Crystals are commonly used in display circuits to determine the output of a given pixel. My question is, when a voltage is applied to a liquid crystal and it changes position, if you remove the voltage, does it return back to its original position? Or does another voltage have to be applied to return the liquid crystal back to it's original state?
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    899
    Welcome to AAC.

    Yes, upon removal of the voltage the molecules relax back to their pre-changed/aligned state. Functionally, however, one must "erase" a character that has been written. That is due to the fact that retention of a character on a screen is due to continual rewriting from the RAM of the display. There are new displays that are "zero power" and do not need to be refreshed. That type is described here about halfway down: https://en.wikipedia.org/wiki/Liquid-crystal_display

    However, there is a phenomenon called persistence in which the molecules do not completely relax upon stopping the electrical power. Here is a description: https://en.wikipedia.org/wiki/Image_persistence It takes several days for that to disappear.

    John
     
  3. patthehat033

    Thread Starter New Member

    Jul 28, 2012
    2
    0
    Thank you, John, for the response! I read through those links, that is all very interesting.

    Do you know how big those zero-power liquid crystals tend to be? I couldn't seem to find any information on that. In terms of their diameter, length etc.
     
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