Adaptive UDFPS Fingerprint Enrollment for Variable Finger Sizes

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Solution Overview

Problem

Existing fingerprint scanners with local under-display fingerprint sensors face challenges in efficiently enrolling fingerprints due to varying finger sizes, leading to under-enrollment or over-enrollment issues, which degrade the user experience and increase the number of touches required.

Innovation Solution

An adaptive fingerprint-enrollment method that adjusts the number and location of enrollment touches based on fingerprint characteristics, using visual guidance and feedback to optimize coverage and minimize the number of touches needed, while ensuring high-quality image capture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed number of enrollment images is used for all users, then the enrollment process is simple to implement, but large-size fingerprints may under-enroll and small-size fingerprints may over-enroll

Engineering Contradiction:
Improveenrollment scheme simplicityVSAvoidadaptability to different fingerprint sizes
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic enrollment scheme that adjusts the number of enrollment images based on the detected fingerprint size. The system determines whether to perform single-image or multi-image enrollment based on real-time fingerprint characteristics, making the enrollment process adaptive rather than static. This resolves the contradiction by maintaining simplicity through automated detection while achieving adaptability through conditional enrollment strategies.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of enrollment image count based on fingerprint size detection. For small fingerprints, it uses fewer images (single-image mode), while for large fingerprints, it uses more images (multi-image mode). This parameter adjustment directly addresses the contradiction by optimizing enrollment quality for different fingerprint sizes while maintaining a simple underlying framework.

Inventive Principle:
Principle #35Parameter changes

2Area of stationary object

If multiple enrollment images are captured to ensure complete coverage, then coverage of large fingerprints is improved, but the number of touches and time required increases

Engineering Contradiction:
Improvefingerprint coverageVSAvoidenrollment time
Core Design Contradiction:
Area of stationary objectVSLoss of time

Solution Approach 1:

The patent applies partial action by capturing only the necessary number of fingerprint images based on size detection. Instead of always capturing multiple images, the system captures single images for small fingerprints and multiple images only when needed for large fingerprints. This eliminates redundant captures, reducing enrollment time while maintaining adequate coverage through conditional multi-image enrollment for large fingerprints.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of operation

If a uniform enrollment scheme is used for all fingers, then the system is easy to operate, but the user experience degrades due to under-enrollment or over-enrollment

Engineering Contradiction:
Improveenrollment operation simplicityVSAvoidenrollment quality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system performs self-service by automatically detecting fingerprint size and determining the appropriate enrollment strategy without user intervention. The device autonomously decides whether to use single-image or multi-image enrollment based on detected fingerprint characteristics, eliminating the need for users to manually configure enrollment parameters. This maintains ease of operation while improving reliability through adaptive quality control.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses feedback from fingerprint size detection to adjust the enrollment process. By detecting the actual fingerprint size and using this information to determine the appropriate number of images to capture, the system creates a closed-loop control system that optimizes enrollment quality. This feedback mechanism ensures reliable enrollment outcomes while keeping the user experience simple.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4288943B1Adaptive fingerprint-enrollment to finger characteristics using local under-display fingerprint sensors in an electronic device
Publication Date: 2026.02.18 GOOGLE LLC
  • EP4288943B1 patent drawingFigure 1
  • EP4288943B1 patent drawingFigure 2
  • EP4288943B1 patent drawingFigure 3

AI summary

This document describes methods and systems of adaptive fingerprint-enrollment to finger characteristics using local under-display fingerprint sensors, UDFPS, in an electronic device. The electronic device includes an adaptive-enrollment module that determines characteristics of a fingerprint based on information corresponding to a touch input detected by a touch-display device, including size and shape of an area of the touch input. Based on the fingerprint characteristics, a number and location of enrollment touches used for completing enrollment of the fingerprint are adjusted to minimize the number of enrollment touches required to complete the enrollment, minimize the amount of time needed to complete the enrollment, and maximize coverage of the fingerprint. The adaptive-enrollment module also provides visual guidance to guide the user to touch the adjusted locations of the enrollment touches and, if needed, feedback to instruct the user to adjust the location of their finger to align with the visual guidance.