>> Seriously, is it normal for LCDs to get warm during operation?
> 
> If they have a backlight, yes, because LEDs and CCFLs are only about 10% 
> efficient at converting electrical energy to visible light.  A typical 
> monitor might need around 5W of backlighting power, most of that is 
> converted to heat.


the bottom?

>> ...is 50 N a lot?
> 
> About 5 kg.  Significantly higher than the force you usually use to 
> write/press with.

5 Kg? Yeah, that is quite a bit... [Hmm, I wonder how much a human arm 
weighs?]

>> Heee, do you remember the old laptops with the blue/purple monochrome 
>> LCDs? Where if you touched the screen, the whole picture rippled 
>> slightly?
> 
> They still do, if you don't have any protection on the front.  My two 
> monitors and my laptop screen here certainly do.

*pokes it* Oh yeah, mine too. :-)

But it's not blue and purple. It's real colour. Even *our* equipment 
isn't *that* ancient. ;-)

>> [Actually, our photocopier has a display like that. And I think it 
>> needs a screen saver, cos some of the controls are well burnt into it! 
>> I didn't think LCDs could "burn" like that?]
> 
> They can if you don't keep the average voltage across each pixel exactly 
> zero volts.  A bad/cheap driving circuit can easily allow enough of a DC 
> voltage to start to screw things up after years of operation.  However 
> usually the burn-in is not permanent, and disappears after some period 
> (can be up to an hour or so with very slow displays).  Must admit I 
> don't know the details because the displays we work on are not allowed 
> to have any visible burn-in at all.

Well, it *is* a 2-year old photocopier. And it runs 24/7. (Although 
actually after a while it goes into a power-save mode where IIRC the LCD 
shuts down too.) That's a touch-sensitive display, come to think of it. 
But it doesn't ripple all that much... hmm.

I wonder... If you wanted to go all mad-scientist, how hard would it be 
to concoct a chemical which forms a vaguely-functional LCD?

[NB. I once tried to make an oscilator at school. The damn thing never 
actually produced any sound. It did, however, heat up the two power 
transistors with remarkable efficiency - I would never have believed 
that 9V was enough to burn your finger on...]

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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