Fingerprint reader as a means of authenticating a user
To date, the computerization of societymakes it necessary to search for various ways to restrict access to information stored on the computer. And the system of authorization and user authentication by password is one of the most common, although it has many shortcomings. An alternative to password protection can be authentication based on the user's biometric parameters, in particular fingerprint. And this requires only a fingerprint scanner and the corresponding software that comes with the device.
The fingerprint reader is aA device that reads a finger image with all its features in the form of a papillary pattern and transmits the result of scanning to the software. A specialized application compares the resulting image with the sample created in the biometric password generation step.
Types of fingerprint scanners
All fingerprint scanners, which are currently used, can be classified into three groups based on the physical principle of operation:
- semiconductor (silicon);
- optical;
- ultrasonic.
Semiconductor scanners
This type of scanner gets an image on thebased on the properties of semiconductors, which vary in the area of contact between the papillary pattern and the scanner. This type of scanning devices can be based on several technologies:
- Capacitive scanners. The work of such scanners is based on the effect when the capacity of the pn junction in a semiconductor device changes when the crests of the papillary pattern and the elements of the semiconductor matrix are in contact.
- Sensitive to pressure scanners. The fingerprint scanner of this type uses a special matrix of piezoelements in its work. When the finger touches the matrix, the crests exert pressure on it, and the cavities, respectively, do not. Based on the pressure applied to the matrix, an image is formed.
- Radio frequency scanners. Scanners of this type consist of micro-antennas that generate a weak signal, and the resulting image of the fingerprint is formed from the result of the electro-motive force in response to the papillary pattern.
- Stretch thermal scanners. The same as thermal scanners. The only difference is that the finger must be drawn along the scanning surface, and not attached.
- Capacitive drawing scanners. The technology for obtaining the image of the papillary pattern is the same as in the capacitive, but the method of production is different in that the finger is drawn along the scanning surface.
- Radio frequency scanners. The principle of operation of these devices is the same as in radio frequency devices, but the method of image acquisition is not the application of a finger to the device, but in carrying the finger along its surface.
Optical scanners
- FTIR scanners. These devices use the effect of disturbed internal reflection.
- Fiber-optic scanners. The fingerprint scanner is an optical fiber matrix, each fiber of which contains a photocell.
- Electrooptical scanners. The image is obtained from an electro-optical polymer, which in its composition has a light-emitting layer.
- Optical broaching scanners. This type of equipment is a refinement of optical devices in which you need to draw a finger across the surface to obtain an image, and not to apply it.
- Roller scanners. To obtain an image, you need to slide your finger along the roller, where fingerprints with papillary patterns are taken.
- Contactless scanners. The finger is scanned in a non-contact way. The finger is applied to the hole where it is illuminated by several sources, and the built-in camera captures the image of the finger.
Ultrasound scanners
This type of device scans the surface of a fingerultrasonic waves, and on the basis of the measured distance of the reflected waves from the depressions and protrusions an image is constructed. This type of device differs from the ones discussed above in that the result of scanning is more qualitative.
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