Progressive Fingerprint Capture Rate for Wet Finger Authentication
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Solution Overview
Problem
Fingerprint sensors in electronic devices often require separate authentication steps, which can be inconvenient and inefficient, especially when performing other tasks, and struggle to handle varying finger conditions such as wet and dry fingers effectively.
Innovation Solution
An electronic device with a processor and finger biometric sensing pixels that generates a series of finger images at a progressively slower rate as the finger settles, determines a quality factor for each image, and selects the best images for matching based on factors like contrast, deformation, and ridge flow, allowing for efficient authentication and enrollment across different finger conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fingerprint sensor captures images at a constant fast rate, then authentication speed is improved, but image quality for wet and dry fingers deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant capture rate to a dynamic progressive capture rate that adapts over time. The system starts with a first capture rate for initial images and then transitions to a second, slower capture rate for subsequent images, allowing the capture process to evolve dynamically to match the settling behavior of different finger conditions (wet vs. dry), thereby resolving the contradiction between speed and quality
Solution Approach 2:
The patent changes the parameter of capture rate from a single constant value to a time-varying parameter that takes on different values at different stages of the capture process. By implementing a progressive capture rate that slows down over time, the system optimizes both the speed of authentication (through initial fast captures) and the quality of fingerprint images (through subsequent slower captures), directly addressing the technical contradiction
2Reliability
If a fingerprint sensor requires separate authentication steps, then authentication accuracy is improved, but user convenience deteriorates
Solution Approach 1:
The patent merges the authentication process with the normal device usage workflow by implementing continuous background fingerprint capture and processing. Instead of requiring users to pause their current task and perform a separate authentication action, the system continuously captures fingerprint images at progressive rates and processes them in the background, combining security verification with seamless user experience
3Reliability
If a fingerprint sensor captures more images to handle varying finger conditions, then authentication reliability is improved, but processing time increases
Solution Approach 1:
The patent implements periodic action through its progressive capture rate mechanism that systematically captures images at different time intervals. The system uses an initial faster capture phase followed by a slower capture phase, creating a structured periodic pattern that efficiently collects sufficient fingerprint data from various finger conditions (wet, dry, settling) while maintaining controlled processing time through the predetermined progressive rate schedule
Data Source
AI summary
An electronic device may include finger biometric sensing pixels and a processor capable of cooperating with the finger biometric sensing pixels to generate a series of finger images at a progressively slower capture rate as a finger settling increases over time from initial placement of a user's finger adjacent the finger biometric sensing pixels. The processor may also be capable of cooperating with the finger biometric sensing pixels to determine a quality factor for each image in the series thereof, and select at least one image from the series thereof for matching and based upon the quality factor.