Redmi implemented the In-Display fingerprint scanning feature on the LCD screens successfully. The Redmi global General manager just announced the technology in detail that, the new technology first experimented on the Redmi Note 8 Pro LCD screen & it’s working fine. Also, he attached the video reference of the LCD screen fingerprint scanning feature on the Redmi Note 8 Pro. Now let find how the In-Display fingerprint scanning works on the LCD screens. 
Generally, the In-Display fingerprint scanning works only on the super AMOLED & OLED displays & not work on LCD display. Since the LCD screens having a backlight behind the displays so, the overall screen size is more than AMOLED screens. Also, because of very thick display size & backlight module In-Display fingerprint scanning is not possible on the LCD screens. Therefore, most probably fingerprint scanner will be located on the rear sides if a mobile equips with LCD display. Similarly, nowadays brands also, keeping the fingerprint scanner at the sides of the display along with power button like recent launches of Realme 6, Realme 6 Pro, POCO X2, Redmi K30, and most of the Honor smartphones. 
Likewise, compared to the rear, side-mounted fingerprint scanning, In-Display fingerprint scanning is most reliable & convenient for daily usage also, most consumers wishes the same. But, keeping the AMOLED displays on the budget & the midrange price segment will not be possible for the brand because the AMOLED screens are more costly compared to LCD screens. In order to overcome this issue, Redmi is a first brand experiment the In-Display scanning feature on LCD screens. For that, Redmi used the Redmi Note 8 Pro to experiment with this feature. 

Redmi Experiment In-Display Scanning on LCD screens

The principle of LCD display fingerprint scanning works just by record the impressions of the fingerprint and sends it back to the sensor located below the screen and finally, matches with the user initial fingerprint impression. However, the LCD screens are having the backlight module beneath the screen so transmission of the optical or ultrasonic signal is not possible directly. But there is a channel is needed to convey the recorded fingerprint impression to the sensor located behind the LCD display. 

The Redmi research & development team used the innovative infrared high-transmittance film material which greatly improves the transmittance of infrared light that could not pass through the screen. The infrared transmitter located at the bottom of the screen emits the infrared light after the reflection of the fingerprint on the display. After that, it penetrates the screen and glows the fingerprint sensor to complete for the fingerprint scanning verification. This is how fingerprint scanning works on LCD screens. As said already, Redmi is a first brand brings these feature similarly, more brands will soon implement these feature to overcome the side & rear-mounted fingerprint scanning. Therefore, hereafter upcoming budget & mid-range mobile sports with LCD display will also, feature with In-Display scanning technology. Also, it still unknown, whether the upcoming Redmi Note 9 series will feature in-display fingerprint scanning or not. 
Likewise, let me know, What is you preference on using the fingerprint scanning whether, In-Display or Rear-mounted or Side-mounted. Please drop your comments below in the comment box.