Showing posts with label fingerprint scanning. Show all posts
How Fingerprint Scanning Works: Capacitive Scanning
Unlike optical scanning which generates an image of a person's fingerprint by using light, capacitive scanners use electrical currents to achieve that. The sensor used in this scanning technology is made up of one or more semiconductor chips which is connected to an inverting operational amplifier; each chip is made up of two conductor plates. This very complicated device cleverly reads each fingerprint by measuring the different electrical voltage given by the ridges and valleys of each finger. The processor embedded into the scanner then reads the voltage output and puts together a picture of the scanned finger. From there it decides whether or not it matches up with authorized prints in the database.
Capacitive scanners have two advantages over optical scanning: 1) It requires an actual image of a fingerprint in order wot work properly and cannot be tricked by simply manipulating patterns of lights that make up the impression of a fingerprint. 2) Due to the size of semiconductor chips, capacitive scanners tend to be smaller than its optical counterpart.
by FingerTec USA
Wednesday, 11 July 2012
How Fingerprint Scanning Works: Optical Scanning
You walk up to the door, clean off your thumb, place it on the door's new, futuristic fingerprint scanner and you open the door and walk through without a second thought. You have gotten used to it to the point that it has become as second nature to you as opening and closing your front door when you leave home for work. But have there been times when you thought about how fingerprint scanning actually works? If so, here are a few answers to your questions.As you may know, fingerprints are very special identifiers unique to each person - even twins do not have the same fingerprints. The two most common fingerprint scanning techniques used are optical scanning and capacitance scanning. Optical scanning works in much the same way as digital cameras do. Using a charge coupled device (CCD), the optical scanner uses photosites that generate an electrical signal that respond to light. These photo sites record the light and dark pixels that make up the image of the fingerprint. Then a built-in device converts the signal into a digital image that the scanner can use to judge whether or not the fingerprint is valid.
Next time, we will discuss how capacitance scanning works.
by FingerTec USA Tuesday, 3 July 2012
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