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LCD's

Discussion in 'Electronic Basics' started by Abstract Dissonance, Jan 30, 2006.

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  1. I brought some LCD's. One was a package(contained some circuits and stuff)
    and the other was simply the display itself with no electronics(at .2$ a
    piece I thought it couldn't hurt to buy a couple).

    Anyways, I have no idea how they work and I took 1 of each and decided to
    tear them apart.

    The one with no circuitry has 2 glass planes with a backing on them that is
    silvered and some other semi-transparent mask. I tore the layers apart just
    to see whats going on but I couldn't really tell. On the glass though I can
    see what apears to be wires(and the only thing that looks like one could
    attach something to it)... on another piece I decided to take a 9V and
    "hook" it up to the wires and I can generate lines across the display... but
    strange thing is that sometimes it does it when I just press on the wires or
    something(not sure whats going on here... maybe static electricity?)

    On the one with the circuitry I tore it apart too and basicaly looks the
    same except where the wires are it has a long rubber like wire... I did the
    same thing with the batter and I could make lines(but not much else).

    Two questions I have is how does the LCD actually work... say, do I apply a
    voltage across two wires and it makes a pixel light up or what? do each wire
    have a function(like is there a ground and hot and the rest are controls or
    what)?

    Also, on the layers what actually is the liquid part? is it inbetween the
    two glass plates or was it the stuff I ripped off the back? (I'd guess these
    are some type of polarization things or something and the liquide is
    inbetween the two glass plates since)

    Oh, is there a way to buy those plastic wire things so I could use the LCD's
    that don't have them(I could try and make my own pcb boards to connect with
    them?)... ofcourse I'd have to know what those wires do though.

    Thanks,
    AD
     
  2. Anyone know what I'm talking about or am I just not making any sense? ;)

    Jon
     
  3. The rubbery thing is called a 'Zebra strip' and is a (clever) multiway
    electrical connector.
    The Black bits are the conductors. The white bits are insulators. Place the
    strip over the (nearly transparent) electrodes deposited on the glass and
    there will always be enough Black bits available to cover any of the LCD
    electrodes with (at least) one connection point. (Same goes for the PCB
    connection points)
    I've not seen Zebra strip on general sale.
    The LCD segments take virtually no power, so static or finger leakage is
    enough to turn them on.
    Yes, putting a DC across a segment or pixel will turn it on. Yes, the liquid
    is between the glass plates,(the old displays had enough chemicals to feel
    'wet' when broken).
    Most of the effort in LCD construction is involved with trying to get a good
    'on' visibility, with stuff that offers pretty crap contrast in the first
    place and is the reason for all the layers.
    The 'liquid' stuff ages rapidly with just a DC connection, so displays are
    arranged to be fed by a reversing DC ('ac') drive.
    Methods of arranging this 'ac' are legion and is best to look at each
    product's datasheet to figure out how the segments, pixels, commons and
    backplanes etc, etc, have been implemented.
     
  4. Thanks, Atleast I have some idea whats going on ;) would be nice to be able
    to ge those Zebra strips for my 10 LCD's without them.

    Thanks again,
    Jon
     
  5. Lord Garth

    Lord Garth Guest

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