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Why can't laptop screens be viewed outside like e-readers can? It turns out, they use very different technology. But engineers are working on closing the gap.

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Thanks to Brilliant for supporting this video!

Because you watch SciShow, Brilliant is offering you a 30 day free trial and 20% off an annual premium subscription at Many of us who use a laptop have had the same thought on a beautiful day: I’m going outside to get some work done!

And we’ve all had the same result: Disaster! No matter how bright your screen, all you see is your own reflection  or the glare of sunlight. Meanwhile, folks with e-readers  seem maddeningly unfazed.

Even in bright sunlight, they see just fine. That’s because many e-readers are cleverly designed to use  sunlight to their advantage. The trade-off is that this kind of screen isn’t great at all of the  things laptop screens can do, including display in color.

But that might not be true forever. [Intro music] The fundamental problem with screens is that most of them have a layer of glass. And glass might be great  at letting light through -- which is why we use it for lenses and windows -- but it’s also good at bouncing light back. When one side of a piece of glass is much brighter than the other, someone on the dark side can see through while someone on the bright side only sees their reflection.

Windows are an obvious example: During the day, they reflect sunlight and you can’t see inside. But at night, you can see straight in if the lights are on. And every crime drama has that  dramatic reveal of someone standing on the other side of the interrogation room’s one-way mirror.

In many cases, there’s nothing one-way about it. One side of the glass is just a lot brighter than the other. The same happens when you bring your laptop outside.

Laptops have tiny fluorescent tubes, LED strips, or other lights that shine through some filters and other stuff before exiting the glass screen. Those lights can be pretty bright. They generally outshine reflections from just about any room you’re in.

Which means that inside, you  can see your screen just fine. But Outside -- and this might sound obvious -- sunlight is bright. Maybe a hundred times brighter than a laptop screen.

Even a little reflected sunlight can overwhelm what’s coming from the laptop. So a sunny day reduces your  screen to a very expensive mirror. Manufacturers fight glare in a variety of ways, but there’s always a trade-off.

For example, some anti-glare coatings  are thin layers of material that reflect light from both the top and bottom. If the coating is just the right thickness, those two reflections cancel each other out and you don’t see any reflected light at all. But you have to stack a bunch of layers to account for the whole rainbow, which can be expensive and still isn’t perfect.

E-readers, though, seem like they solved this problem years ago. They don’t have the reflection  issues of phones and laptops, and yet they still have glass screens. And they do it by using sunlight against itself.

Some have what are called reflective liquid crystal displays, or RLCD, like you find in a lot of old calculators. A bunch of stuff is sandwiched between a glass front and a  sort of mirror in the back. Light reflects off both surfaces, with a lot more coming off  the bottom than the top.

So if it weren’t for the stuff in the middle, you’d always see all the  way through to the mirror. That stuff includes a bunch of little capsules called liquid crystals. Zapping them with electricity  moves some material inside of them that turns them from transparent to opaque.

You only need power to change the liquid crystals, so RLCD displaying mostly static pages can last next to forever. And since they only allow or stop external light, the brighter the environment, the more contrast there ends up being between the brightest and  darkest spots on the screen. For darker environments like the indoors, many e-readers also have internal lights.

So why don’t we just use  e-reader screen technology on our laptops? Well, unfortunately, e-readers struggle to show color very well. Working mostly with reflected light means it’s hard to make colors look  the way you want them to.

And putting colored filters in  front of the liquid crystals like backlit screens do would mean blocking some incoming light and dulling the display. Right now, you’ll find color RLCD screens in some electronic billboards, which can have big pixels  that take in lots of sunlight because you see them from far away and don’t notice the low resolution. On a smaller scale, this kind of screen technology isn’t quite ready for the transition to laptops.

But manufacturers are making progress by shrinking the color filters, adding more internal lights to make the device brighter, or even changing the stuff between the glass and the mirror-like surface in back. Some recent e-readers have little capsules with multiple types of responsive materials inside so that applying different amounts of electricity lets through different colors of light. It can’t match the detail of laptop screens, but it may get there.

Meanwhile, traditional screens may be getting a facelift, too. Engineers are testing ways to carve tiny grooves into the surface of the glass to make light’s transition  from air to glass more gradual. Since reflections happen  at sudden surface changes, the etched glass can almost eliminate them.

Every technology has its  strengths and its weaknesses. The path to a better laptop screen may run through RLCD, or another technology entirely. Either way, rest assured that engineers are working on it.

Maybe someday, the only disaster awaiting you when you bring your laptop outside will be that you forgot to charge it. Thanks for watching this SciShow video and thanks to Brilliant for supporting it! Brilliant makes online learning interactive, with thousands of lessons in science, computer science, and math.

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See you in the next video! Outro Music