How Fingerprint Scanner Works


In day to day routine we are using fingerprint scanner in smartphone,punching Id card, aadhar card enrolment and many more.Today we will talk about how your fingerprint works in accurate way.Will also talk about how it important and secure to use fingerprint in our confidential documents.

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This diagram detailed about, How whole process occur from when we tap our finger till result.Like the optical scanner, capacitive fingerprint scanners make an image of ridges and valleys that make up a fingerprint. But instead of printing using light, capacitors use electric current.

The diagram below shows a simple capacitive sensor. The sensor is made up of one or more semiconductor chips containing an array of tiny cells. Every cell include two containing two conductor plates that is converted with insulating layer.the cells are very tiny even smaller than  width of one ridge.

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Two conductor plates make an original capacitor, an electrical component that can store the charge (see how capacitor works for details) The finger surface acts as a third capacitor plate, which isolated from the insulating layers in the cell structure , And in the case of fingerprint valleys, separating the distance between a pocket capacitor plates of the air (from the operating plates to the front or to the finger from the front) Changes the total capacitance capacitor (capacity to handle capacity).

Lets know what happen when you come to scan your finger by just placing your finger, the processor first closes the reset switch for each cell, which shorts each amplifier’s input and output to “balance” the integrator circuit. When the switch is opened again, and the processor applies a fixed charge to the integrator circuit, the capacitors charge up. The capacitance of the feedback loop’s capacitor affects the voltage at the amplifier’s input, which affects the amplifier’s output. Since the distance to the finger alters capacitance, a finger ridge will result in a different voltage output than a finger valley. 

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Scanner processor reads voltage output and determines whether it is characteristic of a ridge or a valley. By reading every cell in the sensor array, the processor can put together an overall picture of the fingerprint, similar to the image captured by an optical scanner and keep one thing important to reads accurate voltage.

Meaningful advantage of a capacitive scanner is that it requires a real fingerprint-type shape, rather than the pattern of light and dark that makes up the visual impression of a fingerprint. This makes the system harder to trick. Additionally, since they use a semiconductor chip rather than a CCD unit, When you compare both capacitive scanners tend to be more compact that optical devices.And though we prefer more to capacitive scanners only due to its compactness.

I hope now you understand how your fingerprint scanner used in daily life for security purpose.But one of the major disadvantage of fingerprint scanner is that It can be used by you when are sleeping and taking some naps By someone without your permission . so now a days more compact and secure is Eye retina scanner which is more secure than fingerprint scanner and more efficient.

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