Gadgets

How a touchscreen works?

February 4, 2016

Sometimes when I really think about the journey from the apes in the jungle to the robots at mars a lot of feelings of surprise, amazement and enthusiasm rush through my veins. In the world of technology when we are ambitious about robots, ironman’s suit, genetics, bio-weapons, nuclear powers and much more. I am sure not only me but almost every one of us is amazed and surprised by the results and applications of daily discoveries and new inventions. This amazement and surprise generally attracts us towards the science part behind that magical device.

Today we are going to talk about the science behind one of the most common magical device that we are always stuck to. Yes!!! You guessed it right its none other than our smartphone. As we all know it comprises thousands of features even there was a time when wireless calling, video sharing, video calling etc. were the concepts which can only be seen in science fiction movies.

So today almost every one of us is carrying a touch screen smartphone. But have you ever wondered how it work and theory behind it. Of Corse you have; so as usual we are here to help you with the complete theory.

How a touchscreen works?

So to start with there are many touch screen technologies like: resistive, projected capacitive, surface capacitive, optical imaging, acoustic etc. but the technology that we generally use in our touchscreen smartphones is either resistive or either capacitive.

Both resistive and capacitive technologies have its own merits and demerits so we will study both the technologies and then you can decide which one is best for you.

We will also focus on the latest updates of technology like in-cell and on-cell technology. And then we will explore more about the super awesome technology that is the 3D Touch by APPLE.

Also read : 10 Best Phones for Senior Citizens

RESISTIVE TOUCH

As the name says resistive touch it really resist your touch and when you press the screen you can feel the screen to be slightly pressed just like a button is pressed.

There are 2 layers in resistive touch screen:

Conductive layer
Resistive layer

And these 2 layers are separated by tiny dots called spacers.

Current flows through the conductive layer at all time but when we touch the resistive layer comes in contact with conductive layer. Thus the electric current changes at that point of contact so as ohms law:

V=IR

So the function corresponding to that point(x, y) is activated.

Advantages of resistive touch are:

More durable and consistent
Stylus can be used

Disadvantages of resistive touch are:

Harder to read due to multiple layers which reflects more ambient light
Less smooth as compared to capacitive touch

Examples of resistive touch smartphones are:

Sony Ericsson	Satio	Resistive
Nokia	N97	Resistive
Nokia	N97 Mini	Resistive
Nokia	5800 XpressMusic	Resistive

CAPACITIVE TOUCH

Unlike resistive touch technology capacitive touch does not work on the pressure of your finger. It works with anything which possess an electric charge along with your skin.

Capacitive touch screens are made up of materials like copper or indium tin oxide. These screens contains electric charges like electrostatic grids of tiny wire. Each wire is as small as a human hair.

In capacitive touch we have:

A glass substrate(nowadays its generally gorilla glass)
A conductive layer
A protective coating
A controller
4 electrodes 1 at each corner

So the electrodes apply a low voltage to the conductive layer creating a uniform electrostatic field.

When a finger touches the screen a small electric charge is transverse to the finger to complete the circuit creating a voltage drop at that point (x, y) on the screen. The location of this voltage drop is recorded by the controller.

Advantages of capacitive touch are:

Multiple fingers can be detected
Smooth touch

Disadvantages of capacitive touch are:

Cannot be used after wearing gloves

Examples of capacitive touch smartphones are:

HTC	Hero	Capacitive
HTC	Magic	Capacitive
Huawei/T-Mobile	Pulse	Capacitive
Motorola	Milestone	Capacitive
Samsung	Galaxy	Capacitive

Also read : 10 Best water resistant Android smartphones

ON-CELL and IN-CELL TECHNOLOGIES

So there are some improvement in the technology by using two new methods known as on-cell and in-cell technologies.

So let us explore both of them:

On-cell technology: actually moving the touch technology onto the outer glass layer.
EXAMPLES of phones with on-cell technology are – Samsung’s Super AMOLED, used in Samsung’s high-end phones such as the Galaxy SIII and Galaxy Nexus.

In-cell technology: to put the touch sensors into the actual display panel.
EXAMPLES of phones with in-cell technology are – Apple’s iPhone 5 and Sony’s Xperia P.

ADVATAGES of using on-cell and in-cell technology are:

Slimmer phone
Better colour saturation- the light does not pass through the different layers

3D Touch

One of the most difficult technologies that apple have engineered is 3D Touch so let us have a detail analysis of this technology.

The best feature of 3D touch is it can sense and differentiate a soft and a hard touch.

How Does 3D Touch Work

There are sensors installed in the display known as the strain gauges, which detects the force generated by the pressure of touch of your fingers.

The 3D Touch is very sensitive in detecting the levels of touch. The haptic technology which simplifies vibrations in touch with the help of a “Taptic Engine”, allows the 3D Touch to differentiate between a soft touch, tap and a hold press.

So mainly 3D Touch technology combines capacitive touch technology+ strain gauges+ taptic engine.

All of this happens in a fraction of a second which provides you the amazing experience of 3D Touch.

Advantages of 3D touch are:

Totally awesome experience with multiple hidden features

Examples of 3D touch smartphones are:

I-phone 6S
I-phone 7
I-phone 7+

At conclusion I would like to add that we love the enthusiasm in you please always ask how, why, when and keep the spark alive in you. Because your spark will surely enlighten the world in the coming future.