The backlight of an LCD isn't itself polarized. A TN LCD display is made of two orthogonal polarization filters with the liquid crystals in between. In their relaxed (twisted) state, the crystals rotate the polarization of the light so that it can pass the second filter. When a voltage is applied, the crystals straighten and the second filter blocks the light.
That would be neat. But it's essentially impossible with a traditional LCD screen - the physics don't work that way.
The way a backlit LCD works is that the backlight produces light, which goes straight into a polarizer. That polarizer absorbs 50% of the light energy - if it absorbed any less, then the light wouldn't be polarized. Then the light passes through the liquid crystal element to another polarizer, which either passes the light through or blocks it completely.
If you assume that half the screen is lit at any given time, it's physically impossible to not absorb 75% of the light in the polarizer. There are really only two ways to improve this, one is to produce polarized light directly, and the other is to return the lost energy to the device some other way (as this does).
LCD screens are really cool! My dad had a half-broken one at some point, and we peeled the outer layer partly off. It was pure white underneath. Just constant white light, no matter what was being displayed.
But if you looked at the pure white with polarized sunglasses, you could see the image! The pixels don't turn on and off, they just change polarization. And there's a thin layer that blocks light of one polarization, but not the other.
One of the biggest reasons LCDs are so inefficient is that they block most of the light. Each R/G/B subpixel blocks everything that isn't that colour and turns it into heat. The polarizer also has to block all the light that is the wrong polarization and turn that into heat.
This means that the backlight has to be incredibly bright relative ambient light. So even if you positioned it to harness the power of the sun as a backlight, it'd be a lot dimmer than the ambient sunlight.
The reflective LCD in the OP is nice because the sun is behind you instead of shining in your face.
TL;DR, you'd end up having to squint your eyes anyway since the display would be much dimmer than the sun you're staring at, unless you rigged up some cardboard so you didn't have to stare into the sun.
I'm sorta surprised by this. Don't liquid crystal displays in laptops do exactly that?: LCDs are a controllably transparent array that is overlaid on a uniform backlight. So why can't one create a set of glasses where the lens are an LCD array without the backlight?
Not all LCD screens require a backlight. Reflective and Transparent LCD's can operate without backlights (1, 2), and the hybrid transflective LCD's can use ambient light and/or backlight to illuminate the image. Transflective LCDs improve sunlight readability without the need for an intense backlight.
All LCD's essentially use a similar liquid crystal pixel that serves as a variable light shutter for polarized light. It's the back- and front-planes (e.g. addition or omission of RGB color filters, different types of backlights, fully or partially reflective layers, etc.) that differentiate different types of LCDs. If you have an old LCD laying around, with many of them you can actually take the different layers apart to access the active or passive matrix LCD panel (you'll end up with a transparent LCD). I did it once with a tiny LCD, it's pretty cool. Then you can play around with adding your own layers/lighting effects.
In that case (rotating the screens) don't get a Twisted Nematic display. I have the Samsung 2443SW, which, like the Samsung panels in the link, has a TN display, and it is simply not usable rotated 90 degrees. The color and brightness gradient from top to bottom is bearable in panoramic mode, since both your eyes see the same color on each horizontal line. Rotated 90 degrees it's simply awful, because each eyes sees a different color/brightness, and the angle between top and bottom of the screen is so much larger.
Nice. I remember doing this to my scientific calculator at school.
Modern colour LCDs are still polarised, so I can only view my phone and tablet in one orientation when wearing my polarised sunglasses. On the plus side, they make for an excellent real life ad-block to those annoying video billboards (which are just portrait LCD TVs).
I wonder how practical it would be to make a private display by removing the polarising film from it and then viewing with polarised glasses.
This article ends disappointingly in a series of mental exercises. The "LCD" involved is the 8-shape commonly used in LCDs to allow any digit to be displayed. There is no discussion about how light traversing a liquid crystal display illuminates time's arrow, nor the change undergone when a liquid crystal is electrified.
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