How Capacitive Touch Screens Work

[@PabloPazosGutierrez]

the important part is at the end but doesn't explain anything about how multi touch works

[@vitalityedge9406]

it checks one point in lightning speed thus registering multiple points

[@Technogroover]

Amazing explanation! Helped me a lot

[@thinkanddo2352]

Thanks!Keep up the great work!

[@YFTOUCH]

Great tutorial!Thanks for your sharing!

[@leozendo3500]

Beautiful use of a breadboard

[@user-vp6ox9lw7x]

Hello! I'm 18 years old student in Korea. I researched on the principle of capacitive touch screen and the criteria of the substance that detects the input several months ago. This is because it was interesting to know that touchscreen even works with materials such as water, salt, and polyethylene. I was able to find out some information about touchscreen, however, it is hard to find any more information about it on the Korean internetT.T If you have any facts about substance that can work on capacitive touchscreen, please help me... I'll will wait for the reply!

[@sathishr5471]

I am now working on this.If i get the answer .I will tell to you.If you already found tell to me

[@mrdeath4446]

Aluminum. In addition to copper, aluminum is another material that works with capacitive touchscreens. While aluminum isn't as conductive as copper, it's still able to conduct electricity - just like your bare fingers. As a result, it's supported by capacitive touchscreens

[@Danacus]

Thanks! I can use this for school

[@lostinthemoonlight]

Finally someone who explains it right.

[@pp2162]

thanks bro , u gave me awesome information

[@husseinghannam1663]

Very good tutorial, thanks a lot

[@alisaghi051]

Nice explanation!

[@RyutakuZaki]

Really EXCELLENT :D

[@madcircle7311]

That really was helpful

[@absoleet]

Tesla says hi at the end.

[@JagadeshRaoThalur]

great work

[@vinay3352]

Hey I just wanted to know your camera arrangement. Is it vertically or horizontally arranged ? Can you help me with the setup ?

[@ThomasHebb]

We shot the whiteboard portions with a handheld camera pointing down at a whiteboard on the floor, with no special lighting beyond the overhead flourescent lighting of the room. I then used Blender to plane-track and stabilize the whiteboard, and to tweak the contrast so the blank space appeared fully white. If you're trying to do something similar, I'd definitely recommend setting up a tripod and lighting when you film instead of trying to fix up the footage in post. Fixing our footage with Blender took me a *long* time...

[@IraiResende]

Excellent.

[@speechfactory4654]

Awesome

[@user-fo2ry2lt7z]

why all my fingers work fine with touchscreens only the thumb finger in my right hand doesn't work ? any one help plllllz ?

[@troyallen8223]

You didn't even have to touch the screen... Just get close enough to it

[@girl4632]

Difference between capacitive sensing and antenna

[@indirajain2782]

My mobile can sense three finger touch at a time

[@andrei4171]

At 0:43 you are drawing a light bulb which is ON with a capacitor in series, DC is not traveling thru a cap so the light bulb can't light.

[@ThomasHebb]

Good catch! You're absolutely right that the light bulb in that circuit won't stay lit. It is worth noting, though, that it will light for a brief period when the battery is first connected, since current has to flow through it in order to charge the capacitor.

[@glassofmilk7141]

How does this effect the graphic on the screen though?

[@ThomasHebb]

The electrodes that we describe in this video are contained in a transparent layer that's in front of the display. This layer, which is called the "digitizer," isn't connected to the display directly. Instead, both the digitizer and the display are connected to the microprocessor that runs your phone or tablet's operating system. When the operating system software running on the microprocessor detects a capacitance change in the digitizer, it knows that you're touching the screen. It then responds to this touch by changing what's on the screen, just like a laptop responds to you pressing a key by changing what's on its screen. Does that answer your question?

[@glassofmilk7141]

+Tom Hebb Oooohhhh, yes it does thanks.

[@cube4547]

The audio sounds bit crushed lol

[@anshulpagariya6881]

Amazing :(

[@user-dd7wz6tn3e]

nice

[@pyroromancer]

the dude sounds like that nilred dude

[@ernminpeck]

What if I am not connected to ground?

[@ThomasHebb]

Great question! It doesn't actually matter if you're connected to ground or not; if it did, capacitive touchscreens wouldn't work, since the human body isn't technically a "ground" for our purposes. For something to be called "ground," it needs two attributes: firstly, it needs to be able to absorb or release an infinite amount of charge without its voltage changing (practically, this just means it can hold much more charge than anything it interacts with); secondly, its voltage needs to be the same as all other things we call "ground" in the same circuit. Your body satisfies the first requirement, since you have much more mass and hence much more charge capacity than phones do. However, it doesn't satisfy the second one, since your voltage (the "ground" I draw at 4:10) isn't necessarily the same as the phone's ground voltage (the ground I draw at 5:00). Luckily, only the first attribute is needed for the capacitive touchscreen effect to work. I haven't been able to find a way to intuitively describe how the effect works when your body is at a different voltage than the phone's ground, which is why I drew the diagram the way I did; however, if you work through the math using conservation of charge and the capacitor equation Q = CV, you'll find that the result is exactly the same regardless of the voltage of the finger touching the screen. All that matters is that the finger stays at a constant voltage regardless of how much charge it absorbs or releases, which is true for your body to a very good approximation.

[@ernminpeck]

Tom Hebb Wow thanks for the elaborate explanation :)

[@55danielsachs]

Ern-Min Peck I

[@omarromero9038]

There are different types of grounds; for example, floating ground and instrument earth. The human body acts as a floating ground.

[@zrich1585]

Amazing your circuit diagram is wrong, and yes I have electrical engineering qualifications. A direct current would not flow through a capacitor shown in your diagram, it was fine until you made the lamp glow, signifying a current flowing, or if you had shown a alternating current in place of the battery.

[@ThomasHebb]

You're right that the light shown at 0:43 wouldn't remain lit, because a capacitor doesn't conduct direct current. However, the light would light up momentarily when the battery is connected, before slowly fading out as the capacitor charges and the voltage across it decreases. It's similar to what we show at 2:38, except with a charging capacitor instead of a discharging one. But we definitely could have made that more clear-and we probably should have included a resistor in the circuit diagram as well. Thanks for pointing it out!

[@theangusschmaloer]

nice vid, but i you dont sound like a "Tom" XD, but nice vid

[@BrianFrichette]

That was a great explanation, but the woman should have narrated the whole thing. She has a much more enthusiastic and professional sounding delivery.

[@thekaiser4333]

Skip the whiteboard crap. Make a touch-screen.

[@phs125]

I almost thought it's a female with brain!! then I realized its just a kid

[@ThomasHebb]

Three of the four people who made this video are women. Your sexism isn't welcome here.

[@Yrgen2]

He's muslim he can't help it

[@fernandasanroman2058]

Everyone has a brain but some people like you choose not to use it (: