In-Display Fingerprint Sensor Flicker Noise Mitigation
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Solution Overview
Problem
In-display fingerprint identification systems suffer from flicker noise due to mismatched exposure times of light sensing elements and light emitting elements, degrading fingerprint identification accuracy.
Innovation Solution
A sensor device with an exposure time adjusting module that senses raw images, detects flicker noise, and iteratively adjusts the exposure time to synchronize with the frame rate of light emitting elements, mitigating flicker noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rolling shutter is used in in-display fingerprint identification system, then the system can be integrated into display panel, but flicker noise is introduced degrading identification accuracy
Solution Approach 1:
The patent changes the exposure time parameter dynamically to synchronize with the frame rate of light emitting elements. By adjusting the exposure time based on detected flicker noise characteristics, the system eliminates the mismatch between sensing and lighting rates, thereby removing flicker noise while maintaining the integrated display panel configuration
2Ease of operation
If fixed exposure time is used, then the system is simple to operate, but flicker noise occurs due to mismatch with light emitting element frame rate
Solution Approach 1:
The patent transforms the fixed exposure time into a dynamic parameter that can be adjusted in real-time. The exposure time adjusting module continuously adapts the exposure time based on the actual frame rate of light emitting elements and detected flicker noise, converting a static system into a dynamic one that automatically compensates for synchronization issues
Solution Approach 2:
The patent implements a feedback mechanism where the exposure time adjusting module detects flicker noise in the captured image and uses this information to adjust the exposure time accordingly. This closed-loop feedback system automatically synchronizes the exposure time with the light emitting element frame rate, eliminating flicker noise while maintaining ease of operation
Data Source
AI summary
A sensor device includes a fingerprint sensing module, configured to sense a first raw image using a first exposure time; and an exposure time adjusting module. The exposure time adjusting module is configured to obtain a first image according to the first raw image; determine whether the first image comprises a flicker noise; and adjust the first exposure time when the first image comprises the flicker noise, so as to mitigate the flicker noise.