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Subject: Re: Broken LCD :(
From: roland (for_spam_at_gmx.de)
Date: 2004-03-21


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

----- Original Message -----
From: "Chris Holt" <amiga2k_at_cox.net>
To: "Rockbox development" <rockbox_at_cool.haxx.se>
Sent: Sunday, March 21, 2004 4:30 PM
Subject: Re: Broken LCD :(

> On Sat, 20 Mar 2004 20:34:09 -0500, David Litchman wrote:
> > To the best of my understanding, using inverse display would make no
> > difference in power consumption. In an LCD, there are tiny little
> > crystals which are suspended in liquid (hence the name). If a
> > particular cell (or pixel, if you prefer) is on, then a charge is
> > passed through it which aligns the crystals in such a way as to allow
> > light through. If it's off, then the charge is used to align the
> > crystals so that light will not pass through. So regardless of whether
> > or not the pixel is illuminated the same amount of power is used. At
> > least, that's how I understand it. If anyone knows better please feel
> > free to correct me.
>
> Put simply an LCD display consists of two pieces of polarized glass with
> the polarization 90 degrees out from each other. The crystals in between
> are oriented in a twisted pattern in their natural state. The light
> passing through the first polarized layer is twisted 90 degrees and is
> allowed to pass through the second polarized layer (a transparent pixel)
> 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. Simple logic applies here, since when the unit
> is off, the entire screen is transparent, because the crystals are "doing
> the twist". :)
>
> For a more detailed explanation than that:
> http://computer.howstuffworks.com/lcd1.htm
> (probably more than most people want to know about LCDs!)
>
> Chris
>
> _______________________________________________
> http://cool.haxx.se/mailman/listinfo/rockbox
>
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