Fingerprint Recognition Module Leakage Current Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fingerprint identification technologies face challenges in accurately detecting ridges and valleys due to varying leakage currents in sensing devices, which affect the extraction of feature information.
Innovation Solution
A fingerprint identification module comprising sensing units with sensing and control transistors that receive modulation signals with different voltage intervals, a collecting unit to gather output signals, and a calculating unit to determine signal differences, effectively eliminating leakage current influence during fingerprint scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing devices are used to detect fingerprint ridges and valleys, then fingerprint detection capability is achieved, but leakage current in the sensing devices affects measurement precision
Solution Approach 1:
The sensing period is divided into multiple sub-periods (first sensing sub-period, second sensing sub-period, third sensing sub-period) with different scanning line activation patterns. This segmentation allows selective sensing of different pixel rows while others remain inactive, reducing cumulative leakage current effects and enabling differential measurement to eliminate leakage components.
Solution Approach 2:
The patent changes the activation state of scanning lines across different time sub-periods. During the first sensing sub-period, odd-numbered scanning lines are activated; during the second, even-numbered scanning lines are activated. This parameter change in scanning line activation patterns enables differential measurement that cancels out leakage current while preserving fingerprint signal.
2Productivity
If multiple sensing units are activated simultaneously to improve scanning speed, then productivity increases, but leakage current interference increases
Solution Approach 1:
The fingerprint scanning process is segmented into multiple sensing sub-periods where different groups of scanning lines are activated sequentially rather than simultaneously. This time-division multiplexing approach maintains high overall scanning speed while reducing leakage current interference by ensuring that at any given moment, only specific pixel rows are actively sensing.
Solution Approach 2:
The patent employs periodic activation of scanning lines in alternating patterns (odd rows in one period, even rows in the next period). This periodic action allows the system to maintain high productivity through continuous scanning cycles while managing leakage current interference by ensuring non-overlapping active sensing periods for different pixel groups.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate fingerprint identification by ensuring current signals correspond to the sensed differences between ridges and valleys, improving the precision of fingerprint detection.
Implementation Method 1
the light that a light source irradiated onto fingers will result in different reflections due to the difference between ridges and valleys of a fingerprint, thereby leading to variation of intensity of light arriving at a photosensitive device and generating dissimilar photocurrent differences
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present disclosure relates to a fingerprint identification module, comprising: a plurality of sensing units, wherein each sensing unit receives modulation signals when it is turned on, the modulation signal comprises at least one first time interval and at least one second time interval, and the voltage during the first time interval is a first voltage and that during the second time interval is a second voltage; a collecting unit for collecting output signals of the sensing units in the same column in all the first time intervals as a first signal and collecting output signals of the sensing units in the same column in all the second time intervals as a second signal; and a calculating unit for determining the difference between the first signal and the second signal to obtain a third signal and obtaining the fingerprint information sensed by the sensing unit on the basis of the third signal. Through the above technical solution, it is possible to eliminate the influence of the leakage current in the sensing unit during the fingerprint scanning phase, so as to make the current signals on which the calculation of fingerprint information is based correspond to the sensed difference between ridges and valleys of the fingerprint, thereby accurately identifying fingerprints.