Fingerprint Sensing Signal Correction for Display Panel Interference
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Solution Overview
Problem
Fingerprint recognition performance is compromised by environmental voltages generated from LCD panel polarity inversion, leading to signal saturation and reduced accuracy in fingerprint sensing due to superposed voltage signals.
Innovation Solution
A fingerprint sensing signal correction method and device that involves obtaining environmental voltages during a pre-scanning mode, generating correction voltages, and subtracting these from amplified sensing voltages to produce corrected sensing voltages, using a fingerprint sensor, AFE amplifier, A/D converter, digital processor, D/A converter, and subtractor to ensure accurate fingerprint recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polarity inversion is applied to prevent pixel damage, then pixel reliability is improved, but environmental voltage is generated that degrades fingerprint sensing accuracy
Solution Approach 1:
The system performs a pre-scanning operation before actual fingerprint sensing to detect and store the environmental voltage pattern generated by LCD polarity inversion. This preliminary measurement allows the system to prepare correction data in advance, which is then subtracted from the fingerprint sensing signals to eliminate the harmful environmental voltage interference and restore sensing accuracy.
Solution Approach 2:
The system converts the harmful environmental voltage generated by polarity inversion into a useful correction reference. By measuring the environmental voltage during pre-scanning and storing it as correction data, the system transforms the harmful interference into a beneficial reference signal that enables accurate fingerprint sensing through subsequent subtraction operations.
2Quantity of substance
If environmental voltage is large enough, then A/D converter enters saturated state, but this causes loss of fingerprint sensing data
Solution Approach 1:
The system performs a pre-scanning operation before actual fingerprint sensing to detect and store the environmental voltage pattern generated by LCD polarity inversion. This preliminary measurement allows the system to prepare correction data in advance, which is then subtracted from the fingerprint sensing signals to eliminate the harmful environmental voltage interference and restore sensing accuracy.
Solution Approach 2:
The system takes preliminary action by measuring and storing the environmental voltage pattern during pre-scanning mode. This advance detection enables the system to apply corrective subtraction to the fingerprint sensing signals, preventing the harmful environmental voltage from causing saturation and information loss during normal operation.
3Measurement precision
If pre-scanning mode is implemented to obtain environmental voltages, then fingerprint sensing accuracy is improved, but processing time is increased
Solution Approach 1:
The system merges the environmental voltage measurement function with the existing fingerprint sensing workflow by implementing pre-scanning mode that operates before actual fingerprint capture. This integration allows the system to obtain correction data without requiring separate dedicated measurement time, as the pre-scanning is seamlessly incorporated into the overall sensing process flow.
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
The method effectively cancels environmental voltages from sensing signals, preventing saturation and improving the accuracy of fingerprint recognition by maintaining the dynamic range of the A/D converter, thereby enhancing the reliability of fingerprint matching and authentication processes.
Implementation Method 1
the reflected light is received by a light sensor (e.g., a circuit including a photodiode and several thin-film transistors) to convert the reflected light into a voltage signal
Data Source
AI summary
A fingerprint sensing signal correction method for a fingerprint sensing signal correction device including a plurality of fingerprint sensors integrated inside of a display panel of an electronic device is disclosed. The method includes obtaining a plurality of environmental voltages of the display panel during a pre-scanning mode; generating a plurality of correction voltages associated with the plurality of environmental voltages during a signal processing mode; and canceling the plurality of environmental voltages from a plurality of amplified sensing voltages to generate a plurality of corrected sensing voltages during a normal mode.