How Do Touch Screens...Touch?

Summary

The video explains how touchscreens work, contrasting the technology used in phones versus kiosks. It breaks down the layers of a phone's touchscreen - strong Gorilla glass on top, then a grid that stores electric charge, detecting disruption when touched. It notes how gloves and wet fingers interfere with this system. Finally, it explains how screens display color via pixels containing red, green and blue light emitters, which combine to form millions of colors across the high resolution display.

Takeaways

• 😲 Touch screens work by detecting changes in electric charge distribution caused by touch
• 👨‍🔬 Gorilla glass makes touch screens durable
• 😀 McDonald's kiosks use pressure-sensitive touch screens with less precision
• 📱 Smartphones use capacitive touch screens that detect finer changes
• 🔋 The capacitive grid holds electric charge like a capacitor
• 🧠 The processor detects changes in charge distribution when touched
• 💡 Fingers conduct electricity to alter charge while gloves insulate
• 🌊 Wet fingers confuse the screen by activating multiple points
• 🎨 Pixels use RGB colors to create images on the display
• 💰 It costs one subscribe for this smartphone lesson!

Q & A

What are the two main types of touch screens explained in the video?

The two main types are resistive touch screens, like those used in McDonald's kiosks, and capacitive touch screens, which are used in most personal devices like phones and laptops.

What is gorilla glass and why is it important for touch screens?

Gorilla glass is a type of very strong, durable glass that is used for the top layer of capacitive touch screens. It provides protection for the sensitive layers below.

How does a resistive touch screen work?

A resistive touch screen has two plastic layers coated in a conductive material. When pressed, the layers connect to detect the touch. However, it requires more pressure than a capacitive screen.

What are the main layers in a capacitive touch screen?

The main layers are 1) the top gorilla glass layer, 2) a grid that holds a negative charge, 3) a grid that stores a positive charge when the first grid is near, and 4) a processor that detects changes in charge.

How does a capacitive touch screen detect touch location?

The positively charged grid has a precise diamond pattern. When a finger touches the screen, it changes the charge at specific diamonds. The processor matches these locations to the display.

Why don't gloves work on capacitive screens?

Gloves act as an insulator that blocks the electrical interaction between the screen and your finger needed for capacitive sensing.

Why do water drops sometimes cause issues with capacitive screens?

Water is conductive so it can activate multiple points on the grid at the same time, confusing the processor.

How does a screen display color?

Each pixel contains red, green and blue subpixels. By controlling the brightness of each one, any color can be produced.

Where does the glass for touch screens come from?

It starts as high purity silica sand which is melted and molded into glass sheets.

What enables touch sensing in a resistive screen?

The two plastic layers are coated in a conductive material that allows electricity to pass between them when pressed.

Outlines

00:00

😲 How Touchscreens Work

Explains the components and functionality of a touchscreen. A touchscreen is made of strong gorilla glass with a grid of conductive material that creates an electric field. When you touch the screen, it detects the change in charge in that grid section and interprets your touch. There are two main types - less sensitive but more durable plastic/glass screens used in kiosks, and highly sensitive capacitor-based screens used in phones and laptops.

Keywords

💡Gorilla Glass

Gorilla Glass is a type of very strong, damage-resistant glass used to make touchscreen displays. It undergoes a chemical treatment to increase its durability and resistance to cracks and scratches. This glass is what the video says phone and other device screens are typically made of, allowing them to withstand frequent touching and tapping.

💡Conductive Material

A conductive material allows electricity to pass through it easily. The video explains how both layers of the touchscreen on a McDonald's kiosk are covered in a conductive material. When the two layers touch, it completes a circuit and generates a signal.

💡Grid Pattern

The video describes how the conductive material on a McDonald's kiosk touchscreen is applied in a precise grid pattern. This allows the device to detect exactly where on the grid a touch occurs by sensing changes in electrical signals across the grid.

💡Capacitor

A capacitor is a device that stores electric charge. The video explains how the touchscreen in phones and laptops acts as a kind of capacitor, storing positive charges on its top layer. When something conductive like a finger touches the screen, it changes the charge at that point, allowing the device to detect the touch.

💡Processor

The processor is the brain of a computing device. In a phone, the processor analyzes electrical signals from the touchscreen and correlates changes to coordinates on the display, determining what the touch inputs represent and taking appropriate actions.

💡Pixel

A pixel is a tiny dot that makes up what you see on a digital display. Pixels come in three colors - red, green and blue - and by varying their brightness and combining colors, pixels can create any color and form images and text.

💡Dimmer

Each pixel has a dimmer, which controls how bright it appears. By adjusting the red, green and blue dimmers in different combinations, any color can be produced by the pixel.

💡Insulator

An insulator does not conduct electricity well. The video explains why touchscreens may not respond to input from insulating materials like gloves, because they do not alter the electrical charge like skin and conductive objects do.

💡Electric Field

An electric field surrounds electrically charged particles. In a phone touch screen, the layers of conductive grids create an electric field. Bringing another conductor like a finger into this field distorts it, allowing the phone to detect the touch.

💡Subscribe

This refers to subscribing to a YouTube channel. After explaining how a touchscreen works, the video humorously says this knowledge will "cost you" a subscription to the channel.

Highlights

Glass is made by melting high purity silica sand and pouring it into a mold.

Glass is given a chemical treatment to make it very strong, called gorilla glass.

Touch screens have a conductive material in a grid pattern to detect touches.

The grid allows the processor to match touches to what's on the screen.

Some touch screens use pressure while phones use capacitance.

Phone touch screens have 4 layers - glass, 2 grids to hold charge, and an insulator.

The grids act as a capacitor to store charge and detect changes from touches.

Touches change the charge in the grids, detected by the processor.

Bare fingers work by conducting electricity to change the charge.

Gloves don't work because they are insulators that block electricity.

Wet hands confuse the screen by activating multiple points.

Pixels have red, green and blue subpixels to create any color.

Varying the dimming of the subpixels generates different colors.

Millions of pixels together can make any image on the screen.

The touch screen layers and pixels make the displays functional.

Transcripts

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 touchcreen 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 slather 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 use es 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 cuz it's

easier to explain the grids are made

with a material called I 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 build an electric field and

it's used in a ton of stuff so if you

were to put something that inducts

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 y 173 then the chip in your phone

will look at what's displayed on x50 y

173 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 touchcreen 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 of 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