發表於 Posted on: 2016-05-04 0:39

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Mobile phones use one of three types of fingerprint sensors:

Optical: This is the oldest method. It is much like taking picture of the fingerprint. This type can be fooled by an image from a printer.

Capacitive: This is the most common type today. It is by measuring the capacitance between the sensor and the "ridges and air gaps" on the fingertip. Adding any kind of tape over the sensor would likely adversely affect its calibrations.

Ultrasonic: This is the latest fingerprint scanning technology. Much like radars, this is by measuring the reflection of an ultrasonic pulse reflected from the finger. Adding any tape over it would likely adversely affect its calibrations.

Much of the time in fingerprint recognition is not in the scanning but in the interpretation of the data scanned. Delays usually are results of "No Match". The secret in fast recognition is keeping the sensor clean and scratch free.

發表於 Posted on: 2016-05-04 10:58

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