Fingerprint detection system having automatic gain control function and automatic gain control method thereof

Abstract

The invention relates to a fingerprint detection system having an automatic gain control function. The fingerprint detection system comprises a fingerprint sensor which comprises a fingerprint sensing unit array comprising a plurality of sensing units, a rapid scanning control circuit for selecting at least a part of the sensing units in the fingerprint sensing unit array as effective sensing units, a gain control circuit which comprises an ADC (Analog to Digital Converter) array and is used for converting an electric signal into digital fingerprint image information, an image gray value counting unit for counting the gray level distribution information of a fingerprint image, and an adaptive judging circuit for defining the type of the fingerprint image according to the gray level distribution information of the fingerprint image, wherein the gain control circuit is further used for receiving the output of the adaptive judging circuit and adjusting the gain of each effective sensing unit according to the type of the fingerprint image in order to correct the digital fingerprint image information and outputting the corrected information. The fingerprint detection system is wide in application range, high in stability and consistence and low in power consumption.

Description

technical field [0001] The invention relates to the technical field of fingerprint collection. In particular, the present invention relates to a fingerprint detection system with automatic gain control and an automatic gain control method thereof. Background technique [0002] As people's requirements for information security are getting higher and higher, living biometric authentication and identification are more and more used in people's daily life. Fingerprint authentication has high reliability and cost-effectiveness in biometric authentication, and has become the mainstream of current biometric authentication. At the same time, fingerprint acquisition technology is also developing rapidly, and fingerprint sensors with lower cost, smaller size, lower power consumption and high dynamic range will occupy a huge market. Therefore, fingerprint sensors with the above advantages have become the focus of current research. Among them, the capacitive fingerprint sensor has bec...

AI Technical Summary

Problems solved by technology

Because this method can only control the gain of ADC21, its adjustment range is limited, and in some applications, the valley and ridge of the fingerprint cannot be distinguished.

[0007] Greater progress is expected in many applications of personal authentication and identification of fingerprints, but unfortunately current fingerprint sensors and their associated circuits are too large and expensive, which on the one hand brings instability to fingerprint identification; On the other hand, the fingerprint image collected by the traditional fingerprint sensor varies greatly with the difference of individual fingerprints and different collection environments, which has strict requirements on the recognition algorithm; in addition, the change of the manufacturing process also leads to the sensor produced inconsistency

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