How Does Fingerprint Under Display Works? Optical Scanner & Ultrasonic Scanner

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All of us use security features in our smartphone, some people use face unlock and some use strong pin or pattern password. But there is something new and something special, that is “In-Display Fingerprint”.

What Is In-Display Fingerprint?

If I explain you in simple language, there is a camera under display which takes a photo of your finger either it is your finger or thumb, and then it matches that photo with your finger that is it same or not, and On that base either your phone Gets Unlock or you get a message of “Try again”.

How Does It Work?

Now you are thinking that how it works under the display?  so this technology works only on AMOLED Displays, where there is no backlight. And if I talk about IPS or LCD Display, they have a backlight display and are not transparent. But in AMOLED Displays the pixels light themselves and take pictures through these gaps between the pixels.


Now you are thinking, that is that a real photo? Then of course yes. In Optical displays, there is a sensor under the display. When you register your finger for the very first time. You will see that there is a Greenlight which comes. So basically what does this green light works?

Actually, It projects a light on your finger based on where does your finger have ridges, valleys and curves. Then light reflects back through them and the light goes under the display and makes a complete map of your finger through that photo.

And data stores only in the Secure Zone of the Processor so that no one can access it. And when you scan your finger with different angles, it saves that data.

After that whenever you touch the fingerprint sensor, that green light comes to your finger and reflects back and makes an image and then it checks that is that your finger or not and over the time it learns this process and increases the unlocking speed.

Can We Improve This?

So we can only unlock our phone by touching on that small area? can’t we increase that touching area? So yes, we can increase that touching area.

In future, we may see that kind of technology in our phone where we can touch anywhere on the screen to unlock our phone.

We can increase the size of that In-display fingerprint scanner. It may increase the cost but your complete screen can work as a fingerprint sensor.

Advanced Security By Ultrasonic FIngerprint Scanner

And if you want your fingerprint sensor more secure then we can use “Ultrasonic scanner” instead of an “Optical Scanner”.  Because optical fingerprint only make a 2D image whereas ultrasonic fingerprint scanner makes a 3D image of your finger. In this, it transmits the Ultrasonic Waves which then reflects back to that scanner and then makes a 3D map of your finger. And that 3D Map is highly secured and accurate.


We should call this “Under display fingerprint” not “In-Display fingerprint”. Because In display means, that the sensor is in the display, whereas “under display” means that the scanner is under the display.


So this is the mechanism or work of the Under-Display or In-Display fingerprint.



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