Dynamic Fingerprint Sensor Exposure Control for Unlocking Speed
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Solution Overview
Problem
Current fingerprint identification systems have a fixed exposure duration, leading to longer unlocking times due to considerations for worst-quality fingers, which negatively impacts user experience.
Innovation Solution
A method and apparatus that dynamically adjust exposure times by acquiring a second image at a longer exposure duration only if necessary, based on the quality of the first image, allowing for continuous exposure and reducing unlocking time while maintaining high unlocking rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fingerprint sensor uses a long exposure duration to ensure high unlocking rate for worst-quality fingers, then the unlocking rate is improved, but the unlocking time increases
Solution Approach 1:
The patent applies dynamics by making the exposure duration adjustable rather than fixed. The system dynamically selects between first exposure duration and second exposure duration based on image quality assessment, allowing the exposure time to adapt to different finger quality conditions. This resolves the contradiction by enabling short exposure for good quality fingers (reducing time) while maintaining long exposure capability for poor quality fingers (ensuring reliability).
Solution Approach 2:
The patent changes the exposure duration parameter based on image quality feedback. By assessing the quality of the first image and conditionally adjusting the exposure duration to a second value, the system optimizes the balance between unlocking speed and success rate. This parameter adaptation allows the system to achieve high unlocking rates without consistently using long exposure times.
2Loss of time
If the fingerprint sensor uses a short exposure duration to reduce unlocking time, then the unlocking time is reduced, but the unlocking rate decreases for poor-quality fingers
Solution Approach 1:
The system dynamically adjusts exposure duration based on real-time image quality assessment. When the first image quality is sufficient, short exposure duration is used for fast unlocking. When quality is insufficient, the system switches to long exposure duration to ensure successful identification. This dynamic adaptation resolves the contradiction by matching exposure time to actual finger quality conditions.
Solution Approach 2:
The patent implements feedback by assessing the quality of the first image and using this information to determine whether to proceed with short exposure or switch to long exposure. This feedback mechanism ensures that short exposure is only used when appropriate, maintaining high unlocking rates while minimizing unnecessary time delays.
3Reliability
If the system always acquires a second image with longer exposure duration to ensure identification success, then the unlocking rate is improved, but the unlocking time increases
Solution Approach 1:
The patent applies partial action by conditionally acquiring the second image only when necessary. Instead of always acquiring both images, the system assesses the first image quality and only proceeds to second image acquisition when the first image is insufficient. This partial approach maintains high unlocking rates while avoiding unnecessary time consumption from always acquiring two images.
Solution Approach 2:
The system performs preliminary assessment of the first image quality before deciding whether to acquire the second image. This preliminary action allows the system to quickly reject cases where the first image is sufficient, avoiding the time cost of acquiring and processing a second image unnecessarily, while still ensuring high unlocking rates for difficult cases.
Data Source
AI summary
Embodiments of the present application provide a method for fingerprint identification, and electronic device. The method includes: acquiring a first image collected by a fingerprint sensor at a first exposure time; determining whether to acquire a second image collected by the fingerprint sensor at a second exposure time according to the first image, where the second exposure time is continuous with the first exposure time, and a length of the second exposure time is greater than or equal to a length of the first exposure time; performing fingerprint identification according to the first image, or, the first image and the second image. The method, and electronic device of the embodiments of the present application can take into account an unlocking rate and unlocking time, thereby improving unlocking experience of a user.