>> Yeah, those usually just have a silvered back. And, depending on what 
>> it is, they don't always turn completely transparent when "off". 
>> (E.g., the phone on my desk has an 8x8 grid of pixels, and you can see 
>> where the pixels are even when they're supposed to be off. They do 
>> turn very, very black when they're on though.)
> 
> Only if you look at them from exactly the right angle :-)

Hmm, yes... Apparently if I stand in front of my desk phone, all the off 
pixels become completely transparent.

Why is LCD angle-dependent in the first place?

>> We have several items of equipment here that have screens like this. I 
>> first saw them in laptops, about 20 years ago. But now you see them as 
>> touch-screen controls for photocopiers and the like.
> 
> Yes, they are very cheap compared to higher performance displays.  Not 
> just the actual LCD, but also the drive electronics required is much 
> simpler.

I'm guessing making it touch-sensitive makes it more expensive though? 
(How the hell do they do that anyway? And how come the display doesn't 
"ripple" when you do this?)

>> And then, at home I have a keyboard that has a backlit LCD. But it's 
>> yellowy-green, with black pixels...
> 
> The "colour" of a monochrome display is just the combination of the LED 
> colour used in the backlight, and what wavelength the LCD is tuned to 
> block. I guess there are common combinations, but pretty much anything 
> should be possible.

So the keyboard probably has a green backlight and green liquid crystals?

I was under the impression that high-performance displays (e.g., my 
computer monitor) use florescent lighting rather than LEDs. (Although, 
obviously, I don't design LCDs for a living...)

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