Sunday, September 5, 2021

How does the touchscreen of mobile work?

Do you know how one click from your fingertip opened this article on your mobile or tablet? If not, then don’t worry! You have landed on the perfect page where you are going to know how does the touchscreen of mobile work? There are many types of touch screens that have been developed till now, but in this article we are going to discuss only two of them that are most commonly used. One is resistive touch screen and the other one is capacitive touch screen. So let us start!

Resistive touch screen

The most common types of touch screens that are found are resistive type. You must have used it ones if you have an ATM card. Yes, you are right. Resistive type touch screens are used in the ATMs. So how does a resistive type touch screen works?[Read – Why are airplanes painted White?]

Basically, these screens consist of two electrically conductive layers that are bend to touch each other. Among these two layers, one layer is resistive and the other one is conductive, and they both are separated by a gap of tiny dots also known as spacers. These tiny dots help in keeping the two layers separate from each other. An electrical current runs through the resistive layer all the time, but when we touch the screen using our finger, then the two layers (resistive and conductive) are pressed together and the electrical current changes at the point of contact.
Credit - Rosenfeld Media

The controller takes the information from the sensor and determines where exactly the touch has taken place. This information is then sent to the software, which performs the function that is commanded by the software according to that spot. The whole process may look like a long process, but actually it takes few nanoseconds in real time.[Read – What is bitcoin? How does it work?]

There are some advantages and some disadvantages of using resistive touch screens. For example, resistive touch screens are very durable, but they cannot handle multiple touch at a time. Also since they use multiple layers, they are very hard to read.

Capacitive touch screen

This type of touch screen is found in mobiles and tablets. In resistive touch screens, the pressure of our finger is used to bend the layers so that some change in electrical current occurs. But in capacitive touch screens not only digital pen but anything, specifically our finger touch, that has some electrical charge can be used.[Read – Mistake in black hole of Interstellar movie]

That is why capacitive touch screens cannot be used while wearing gloves/clothes as they do not conduct electricity. These touch screens are constructed from materials like indium tin oxide or copper that store electrical charges in an electrostatic grid of very thin hair like wires.
Credit - Rosenfeld Media

Basically what happens is, when we touch the screen using our finger, a very small amount of electrical charge is transferred to the finger to complete the circuit, which eventually creates a voltage drop on that point of the screen. And then the software processes the location of this voltage drop and commands it to perform the necessary action.[Read – How does a refrigerator or fridge work?]

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