LITERATURE REVIEW

JOURNAL 2

FINGERPRINT SCANNER

Fingerprint scanners aren’t just reserved for the very top-tier of smartphones these days, even your reasonably priced mid-ranger can come packing in the additional security hardware.

OPTICAL SCANNER

Optical fingerprint scanners are the oldest method of capturing and comparing fingerprints. As the name suggests, this technique relies on capturing an optical image, essentially a photograph, and using algorithms to detect unique patterns on the surface, such as ridges or unique marks, by analysing the lightest and darkest areas of the image.

CAPACITIVE SCANNER

The most commonly found type of fingerprint scanner used today is the capacitive scanner. Instead of creating a traditional image of a fingerprint, capacitive fingerprint scanners use arrays tiny capacitor circuits to collect data about a fingerprint. As capacitors can store electrical charge, connecting them up to conductive plates on the surface of the scanner allows them to be used to track the details of a fingerprint. The charge stored in the capacitor will be changed slightly when a finger’s ridge is placed over the conductive plates, while an air gap will leave the charge at the capacitor relatively unchanged. An op-amp integrator circuit is used to track these changes, which can then be recorded by an analogue-to-digital converter.

Credit to : Reuban, S. (2014). Desing and Implementation of A Microcontroller Based Automatic Door NAd Visitor Counter.