Transcription
How can a piece of glass know you're touching it? What kind of black magic is this? Like, at one point, your phone screen was literally just sand. And using science and technology, that sand became this. Yes, actually, let me show you how.
Step one: Get some glass. First, melt some high-purity silica sand and pour it into a mold sort of thing. Boom, glass. But that glass breaks really easy. Not good. So, we give that glass a chemical manicure and make it very strong. We call this Gorilla Glass.
Step two: The touch. There are two kinds of touch screens: the one your phone uses and the annoying kiosk at McDonald's. First, let's talk about the McDonald's kiosk. This one has two layers, usually being plastic on top and glass behind it. Both pieces are slathered in a conductive material. That means when they touch, it makes electricity. So, if you put one just a little bit in front of the other and attach them to something, you get a touch screen.
But wait, it knows it's being touched. But how does it know where it's being touched? Well, you remember that slathering from earlier? It's actually a very precise slathering where we lather in a grid pattern. So, if you touch right here, it will send electricity to the processor like this. And the processor can match up with what's on the screen and register if it does anything. Pretty cool, except it sucks and you have to put an annoying, an, an annoying, and you have to put an annoying amount of pressure for it to work. And it's not reliable, but it's more durable and lasts longer, which is why big companies like McDonald's use it so they don't have to maintain it as much.
The other kind is what your phone, laptop, and pretty much any personal device almost always uses. This one has four layers. The top layer is the tough glass we talked about in step one, which, besides being kind of strong, there's really nothing special about this glass. It's just glass. But below that glass, we have two clear diamond-shaped grids with a clear insulator in between them. But I'm going to make them colored 'cause it's easier to explain. The grids are made with a material called ITO, which holds electricity really well. And it's actually the same stuff we slathered on the McDonald's kiosk, but this time, it's just on its own under some glass.
If we zoom in on the bottom grid, we'll see a ton of little electrons just chilling. They do this because there's an insulator in between the two grids, so the electrons are kind of stuck. They really have no choice but to chill. And because these electrons aren't moving, they generate a negative electric field, which causes the top layer to store a ton of positive charges. This, my young Padawan learners, is what we call a capacitor. It builds an electric field and it's used in a ton of stuff.
So, if you were to put something that can conduct electricity close to this capacitor, like a hot dog, it messes up the electric field. This changes the amount of positive charge on that top layer. Now, keep in mind, your phone knows exactly how much charge is supposed to be on each top diamond. So, the processor in your phone does the math and says, "Yo, there's a change in charge on diamond X50 Y173." Then the chip in your phone will look at what's displayed on X50 Y173. And if clicking there is supposed to do something, meaning if you tap right here, nothing happens. But if you tap right here, your phone matches it up with what's on the screen and subscribes to this.
Okay, but why do touch screens work with fingers and hot dogs but not gloves? Also, why does your touch screen act all weird when your hands are wet? It's because, like I said before, your finger and a hot dog conduct electricity. That means when you put your finger near your phone screen, the electricity from the capacitor literally runs through your finger, and that's what makes the change in charge. A glove, however, is an insulator, meaning electricity ignores it, so there's no change in charge.
Then you might say, "But what about water?" Water conducts electricity, and that's true. The problem is, when your hands are wet, the water activates at multiple points at the same time, and your phone just kind of gets confused.
All right, so we have some glass, the clear magic electricity stuff. But what about the screen itself? The colors? How does that work?
Step three: Display. Everyone thinks they know how pixels work, and they probably do. Basically, if you zoom in on your screen really, really, really, really close, you'll see something called a pixel. Each pixel is made up of three baby pixels that are either red, green, or blue. On top of each baby pixel is a dimmer. So, if you want this pixel to be the color red, you'd completely dim green and blue. If you want the color purple, you'd dim green completely and do 50% red, 50% blue. If you want white, you do them all at 100%. Basically, these three colors can make any color. And because you have millions of pixels, you can make any image. JIT crazy after all, eh? Anyway, that's going to cost you one subscribe. And the McDonald's kiosk is going to ask you a few questions.