Other What's the difference between ultrasonic and acoustic fingerprint sensors?

[racingman]

In regards to next year's iPhones, there are rumours that they will adopt full in-display Touch ID with acoustic or ultrasonic technology. Some articles seem to view them as equals, some say there are slight differences. Can anyone please explain how they're different? Thanks!

 

[Shirasaki]

https://en.wikipedia.org/wiki/Acoustics
https://en.wikipedia.org/wiki/Ultrasound
Based on my preliminary and brief search, I think acoustic method might shake the screen very slightly to detect fingerprint while ultrasonic method emit sound waves through screen to detect fingerprint. One thing certain for me is both are using sound waves in different ways to recognise fingerprint and authenticate.

I am waiting for an acoustic engineer to give a more formal answer.

 

[racingman]

https://en.wikipedia.org/wiki/Acoustics
https://en.wikipedia.org/wiki/Ultrasound
Based on my preliminary and brief search, I think acoustic method might shake the screen very slightly to detect fingerprint while ultrasonic method emit sound waves through screen to detect fingerprint. One thing certain for me is both are using sound waves in different ways to recognise fingerprint and authenticate.

I am waiting for an acoustic engineer to give a more formal answer.

Thanks for the reply! Can anyone please explain further?

 

[Moonjumper]

I thought ultrasonic was a form of acoustics. Maybe the term ultrasonic is being used to signify wavelength, and as a result, accuracy.

 

[JPack]

In regards to next year's iPhones, there are rumours that they will adopt full in-display Touch ID with acoustic or ultrasonic technology.

They are referring to the same thing.

The two main approaches to in-display fingerprint sensor are: ultrasonic echoing and optical imaging.

Ultrasonic works with LCD and OLED while current optical solutions require OLED due to backlight requirements. Optical solutions tend to have a wider sensing area compared to ultrasonic.