There are basically three patterns of fingerprint ridges that are the arch, the loop and the whorl.
The arch is the pattern where the ridges will start from one point of the finger, make an arch in center and end on the another side of the finger.
The loop is the pattern where the ridges will start from one point of the finger, forms a loop and ends on the same side of the finger where is has been started.
The Whorl is the pattern where the ridges will form the circular at the center point.
Following image will show you the detail of all the above.
1. Optical Readers : This is a common type of reader where the readers sensor act as a digital camera and captures the high resolution virtual image of the finger. More high resolution image more the security it will provide.It is available in the market at cheap rates. It actually captures the digital image of the finger and
translates the image into digital information which computer understand. It is ususally used for attandance and access control of any person.It has a disadvantage like if your finger is dirty it will also detect the same. From this type you can easily fool others and use the access of others. Therefore it is not used in paint industry or cement industry.
2. Capacitive Readers : This type of reader uses array of capacitive proximity sensor and it is associated signal processing circuits to create and store digital image of a human fingerprint. It generates complex pattern of an electrical currents which will form digital image of fingerprint. It requires physical presence of human finger, so it is very difficult to fool with this device which is possible with optical reader. This reader is expensive as compared to optical reader and quite safe as compared to optical reader.
3. Ultrasonic Readers : This type of reader are the most recent type of fingerprint readers, they use high frequency sound waves to penetrate the epidermal (outer) layer of the skin. They read the fingerprint on the dermal skin layer, which eliminates the need for a clean, unscarred surface. All other types of fingerprint
readers acquire an image of the outer surface, thus requiring hands to be cleaned and free of scars before read-out. This type of fingerprint reader is far more expensive than the first two, however due to their accuracy and the fact that they are difficult to fool the ultrasound readers are already very popular. The first mobile to use this techonolgy is Le Max Pro smartphone.
4. Thermal Readers : This reader sense, on a contact surface, the difference of temperature in between fingerprint ridges and valleys. Thermal fingerprint readers have a number of disadvantages such as higher power consumption and a performance that depends on the environment temperature.
When you set the fingerprint for unlocking your device for first time, it will capture the high resolution image of your finger and sensed data like ridges, pattern and then it will save in the smartphone. Second time when you place your finger on the sensor it will identify the previous data which was saved in smartphone and if it matches it gives access for unlocking your device.
Xiaomi Redmi Note 3 was the first device to launch Fingerprint scanner in its all the series of mobile.
Benefits of having fingerprint scanner in smartphone
1. Lock or unlock the device or application without remembering the password.
2. Easier, cheaper and faster to setup.
3. Substitute for passwords or pin
4. Payments via fingerprint scanner.