Fingerprint scanners on the display were only available for smartphones with OLED panels, but that will change soon. BOE Technologies is already working on a fingerprint sensor in the display that would work with LCD panels, and Redmi teased a similar approach.
3M is now announcing the development of NITS (Near Infrared Transmission System), which is basically doing the same. Allows smartphones in the lower price range with LCD displays to use optical fingerprint sensors on the display.
3M NITS uses advanced 3M micro-thin optical display films that allow optical sensors to read fingerprints to be placed behind an LCD screen. This new technology offers better security with a full screen for mobile phones and other devices with LCD display systems.
The company states that its solution also works on tablets, laptops and other devices that have LCD panels. Although there is no information about when these solutions will be in consumer goods and when they are commercially available, 3M describes its technology in detail. For details, see the following source link.