Naked Science Forum
Non Life Sciences => Technology => Topic started by: scientizscht on 20/12/2018 22:04:39
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I read some articles online but do not have enough detail to understand how it works. They just say they work with electric current.
Any hint?
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very fruitful suggestions
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How did you manage not to find this?
https://computer.howstuffworks.com/fingerprint-scanner.htm
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How did you manage not to find this?
https://computer.howstuffworks.com/fingerprint-scanner.htm
Ofcourse I read it but it doesn't explain in detail.
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How did you manage not to find this?
https://computer.howstuffworks.com/fingerprint-scanner.htm
Ofcourse I read it but it doesn't explain in detail.
Did you read all 6 pages?
What more detail do you want?
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How did you manage not to find this?
https://computer.howstuffworks.com/fingerprint-scanner.htm
Ofcourse I read it but it doesn't explain in detail.
Did you read all 6 pages?
What more detail do you want?
How do they work in few words?
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Put simply, these devices work in three main ways: imaging, electrical/capacitive fingerprinting and sonic fingerprinting. The complexity and recency of introduction occur in that order.
In imaging, which is the oldest but also the weakest (easiest to fool), a light source at an angle to the skin surface emits a beam or light which reflects off the skin surface and reflections are focused by a lens and detected by photosensitive surface. The pattern of reflections is stored as a 2D image and used to authenticate the user. It's easy to fool because anything that produces the correct pattern will activate the detector.
In capacitative detection, the device compares the electrical capacitance profile of the skin surface, which will change across the skin surface owing to the patterns of ridges and folds. As the pattern of ridges and folds will vary so the capacitance function will vary; this capacitance variation pattern can be used to authenticate the user.
The most recent introduction is an ultrasonic approach. This uses an ultrasound source to bounce sound waves off the surface and store the reflection pattern; this is the hardest to fool but works a bit like the imaging system: the sound waves bounce off the topography of the skin surface in different ways according to the ridge pattern.
I hope that explains things for you?
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Thanks it helps but doesn't answer my questions.
For the second technology, what exactly is happening? The surface you touch your finger releases electrons that bind on your fingerprint beads and create a unique electric field? And how is this electric field is detected? And how the electric charge is generated?
As for the third technology, are we able to produce ultrasound beams and detect their reflection, with a device that is so tiny to fit on a cell phone?
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For the second technology, what exactly is happening? The surface you touch your finger releases electrons that bind on your fingerprint beads and create a unique electric field? And how is this electric field is detected? And how the electric charge is generated?
It's measuring "capacitance" - in other words, and put very basically, the ability of a surface to store charge. The more skin there is in contact with a part of the surface, the more charge that bit of surface can store; the device can measure this and infers the fingerprint pattern from the capacitance distribution.
As for the third technology, are we able to produce ultrasound beams and detect their reflection, with a device that is so tiny to fit on a cell phone?
Yes!
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Like optical scanners, capacitive fingerprint scanners generate an image of the ridges and valleys that make up a fingerprint. But instead of sensing the print using light, the capacitors use electrical current.
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