Tuesday, August 10, 2021

Tower Overviews Optical Fingerprint Technologies

Amos Fenigstein, Managing Director of CIS R&D at Tower, publishes a nice review article "Image Sensors: Leaving Fingerprints Everywhere in the Age of Consumer Data Protection and Security." Few quotes:

There are two major “under screen” optical sensors technologies:
  • a lens-type sensor that uses a system lens and thus uses pixels the size of 5 to 6 microns to resolve the 50um features resolution in the fingerprint, 
  • a 1:1 sensor that does not use a lens and thus, requires large pixels, of around 50um.
The lens-type sensor, if used under LCD, requires an internal light source at the near Infrared regium as the LCD screen is not transparent to visible light. However, if used under OLED, the OLED screen itself acts as the light source and thus, the pixels are required to be sensitive to visible light. This is true for both lens-type sensors and 1:1 sensors under OLED screen (1:1 sensors are not being used under LCD).
The reason to use 1:1 sensors, although it is much larger than a lens-type and as a result are much more costly, is the minimum sensor height that can be achieved only with a lens-less sensor. Such small heights, as small as half a millimeter, is crucial for high end 5G smartphones, where there is only 0.6mm space between the battery on the back and the screen.

The text under the top row of pictures appears to be switched:

No comments:

Post a Comment

All comments are moderated to avoid spam and personal attacks.