How Do Touchscreens Actually Work? 📱

3 min read

Morning ipad kids!

Lemme tell you this funny story.

So, it's 2010, South Korea.

For some reason, the winter was super cold this year.

And people were struggling to activate their smartphones while wearing gloves.

So, you know what they did?

No, they didn't just take their gloves off.

Many actually began wielding snack sausages as squishy styluses:

And they actually worked!

Causing one particular company to see a 40% spike in sausage sales!

So, why do sausages work on touchscreens, but gloves don’t?

And… how do touchscreens actually work?

Alright, so, your smartphone screen is made of 5 separate layers.

First, you got a protective glass layer on the top (you know, for when you drop it).

Then at the bottom you got the LCD screen (this is for the stuff you see).

Then you're just left with the 3 in the middle.

Which are kinda like a sandwich.

The bottom layer has these little vertical lines of a conductive material called sensing lines.

And then the top layer has little horizontal lines of a conductive material also called sensing lines.

And smack dab in between these two is a see-through insulator layer.

FYI, all these layers (except the LCD screen) are completely transparent…

Anyway, these 2 lined layers lay on top of each other, separated by the insulator layer to form a grid pattern.

The points on this grid where those little lines connect are called nodes.

Now, when your phone is turned on, the phone's battery draws electrons to these node thingies and they begin to accumulate there, creating a small electric field.

Screens like these are called Capacitive touchscreens.

Because the little nodes act like tiny capacitors.

(Which basically just means they store a charge.)

So, when you touch one of these screens, your finger interacts with the weak electric field that the screen is producing.

And it shoots a signal into your body.

Which bounces about and then comes back into the screen.

This changes the charge in the nodes that your finger just touched.

Then the phone uses this fancy voltage measuring tech to measure where this charge is coming from, which then tells the phone's microprocessor which part of the screen is being touched.

But why do your fingers or a sausage work but gloves don't?

Well, it's simply because your body, and sausages are full of water.

Not perfect water, water that is loaded with atoms with lots of missing electrons, which makes it positively charged.

So the signal from the phone screen easily passes through into your body… or a sausage and back again.

But the thing is, gloves don't have a charge, so these signals cannot pass through them.

Sorry gloves.

Stay Cute,
Reece, Henry & Dylan 🌈

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