Fingerprint Sensor Impairment Data Suppression
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Solution Overview
Problem
Fingerprint sensors face difficulties in accurately capturing images due to quasi-stationary noise caused by material imperfections and variations, which complicates fingerprint recognition processes.
Innovation Solution
A method involving a fingerprint sensing system that captures multiple images of a user's finger to create a single image representing impairment data, which is then used to suppress noise from subsequent fingerprint images, allowing for real-time adaptation to changing sensor conditions and eliminating the need for offline registration processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sub-μm precision and extremely pure materials are used to eliminate capacitive noise, then measurement precision is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent captures images of impairment data in advance (before actual fingerprint recognition) and stores them for later use. This preliminary capture and storage of noise patterns allows the system to prepare correction data beforehand, eliminating the need for complex real-time noise filtering during actual fingerprint scanning.
Solution Approach 2:
The patent introduces an intermediary process where captured impairment images are processed to generate correction images that are then applied to subsequent fingerprint images. This intermediary correction image acts as a mediator between the raw noisy fingerprint data and the final clean recognition result, simplifying the overall system requirements.
2Measurement precision
If offline registration processes are implemented to capture impairment data, then measurement precision is improved, but loss of time occurs during device setup
Solution Approach 1:
The patent enables the system to automatically capture and process its own impairment data without requiring external calibration equipment or complex offline registration procedures. The fingerprint sensor itself serves to capture the impairment patterns, and the processing unit automatically generates correction images, making the system self-sufficient and eliminating time-consuming setup procedures.
Solution Approach 2:
The patent allows the system to continuously update and refine its impairment correction data over time. Rather than performing a one-time offline registration, the system can capture new impairment images and update correction images continuously, turning what would be a time-consuming setup process into an ongoing beneficial operation that improves accuracy without user intervention.
3Measurement precision
If multiple images are captured and processed to create impairment correction data, then measurement precision is improved, but productivity decreases due to additional processing steps
Solution Approach 1:
The patent performs the computationally intensive image processing to create correction images in advance, before actual fingerprint recognition is needed. By preparing the correction data beforehand and storing it, the system avoids performing complex multiple-image processing during real-time authentication, thus maintaining high recognition speed while still achieving improved precision.
Solution Approach 2:
The patent separates the fingerprint recognition process into two distinct phases: an offline phase where multiple images are captured and processed to create correction data, and an online phase where only simple correction application is needed for actual recognition. This segmentation allows complex processing to occur when speed is not critical, while maintaining fast response during actual authentication.
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
This approach effectively cancels out impairment data from captured images, improving fingerprint recognition accuracy and accommodating wear and tear on the device, while allowing for continuous updating and refinement of noise estimation.
Implementation Method 1
By measuring the capacitance between the surface touched by the user and the sensor at each pixel, the fingerprint of the user may be derived from an image captured by the fingerprint sensor
Data Source
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AI summary
The invention relates to a method of a fingerprint sensing system (101) of enabling suppressing impairment data (120) present in an image captured by a fingerprint sensor (102) of the fingerprint sensing system, and a fingerprint sensing system (101) performing the method.