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Subject: Re: Broken LCD :(
From: Chris Holt (amiga2k_at_cox.net)
Date: 2004-03-21


On Sun, 21 Mar 2004 16:56:43 +0100, roland wrote:
> hi chris,
>
>
>> When you pass current through these crystals, they line up and make
>> the pixel opaque. So... When a pixel on an LCD display is
>> transparent, it is off, no current applied.
>>
>
> i`d like to add a minor correction to this:
> it`s not the current which makes the crystal change their direction
> (and thus changing the polarization).
> it`s the electrical field - and so it`s just the volage causing the
> desired effect. there is a minor current going through the lcd - but
> that is not relevant at all and just a dissipation/leakage
> current,AFAIK.
>
> regards
> roland

Without current, no work is done. I certainly takes a certain amount of
current to generate an electric field. Yes, it is very minor, but it is
required nevertheless. All potential and no current = an open circuit.

(Should you wish to increase the value of your AFAIKs, read the link I
gave)

A quote from the link:

"One feature of liquid crystals is that they're affected by electric
current. A particular sort of nematic liquid crystal, called twisted
nematics (TN), is naturally twisted. Applying an electric current to these
liquid crystals will untwist them to varying degrees, depending on the
current's voltage. LCDs use these liquid crystals because they react
predictably to electric current in such a way as to control light
passage."

Chris

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