Deblurring Finger Images Using Sub-Array Processing
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Solution Overview
Problem
Fingerprint sensors using electric field sensing methods face challenges in capturing clear images when a thick dielectric layer is present between the sensor array and the finger, leading to blurred images due to electric field diffusion.
Innovation Solution
An electronic device with a finger biometric sensor that includes an array of electric field sensing pixels, a dielectric layer causing electric field diffusion, and deblurring circuitry capable of processing image data from sub-arrays to produce deblurred finger images using deblurring functions and coefficients, such as inverse Gaussian functions, to address the blurring caused by the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thick dielectric layer is placed between the sensor array and the finger, then the sensor can operate at greater distances or with protective coverage, but the electric field diffusion causes image blurring
Solution Approach 1:
The patent applies deblurring processing that modifies the electrical parameters of the sensed data to reverse the diffusion effect. By changing the processing parameters (applying deconvolution algorithms), the system compensates for the physical parameter change (electric field diffusion through dielectric) and restores image clarity despite the increased distance or protective layer.
Solution Approach 2:
The system effectively creates a composite processing approach by combining the raw sensed data with deblurring algorithms. This composite processing method integrates the original signal with correction factors derived from the known dielectric properties, producing a enhanced output that maintains clarity despite the intermediate dielectric layer.
2Adaptability or versatility
If a thick dielectric layer is placed between the sensor array and the finger, then protective coverage or greater operating distance is achieved, but variations in the dielectric cause electric field variations and image blurring
Solution Approach 1:
The deblurring processing dynamically adjusts processing parameters based on the sensed data characteristics and known dielectric properties. By changing the processing parameters (such as deconvolution kernel selection and strength), the system adapts to different dielectric conditions while maintaining consistent image quality across varying operating distances and protective layer configurations.
Solution Approach 2:
The system uses feedback from the sensed data itself to guide the deblurring process. By analyzing the characteristics of the blurred image and applying iterative deconvolution algorithms, the system automatically adjusts the processing to compensate for dielectric variations, ensuring reliable image quality regardless of the specific operating conditions or protective layer present.
3Measurement precision
If deblurring processing is applied to the entire array, then image clarity is restored, but processing complexity and computational resources increase
Solution Approach 1:
The patent divides the sensor array into multiple sub-arrays and applies deblurring processing to each sub-array independently or in groups. This segmentation reduces the computational complexity of processing the entire array at once while maintaining image clarity. The divided processing approach allows for more manageable computational loads and can be implemented with fewer resources.
Solution Approach 2:
The system applies deblurring processing selectively to regions where it is most needed rather than uniformly across the entire array. By focusing processing resources on areas with significant blur or highest importance, the system achieves adequate image clarity with reduced overall processing complexity and computational requirements.
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
The solution effectively deblurs finger images by processing image data from sub-arrays based on their respective diffusion functions, improving image clarity and accuracy even with non-uniform dielectric layers, thereby enhancing fingerprint recognition and spoof detection capabilities.
Implementation Method 1
a dielectric layer over the array of electric field sensing pixels and causing electric field diffusion so that the image data output circuitry generates image data corresponding to a blurred finger image
Data Source
AI summary
An electronic device may include a finger biometric sensor that includes an array of electric field sensing pixels and image data output circuitry coupled thereto and capable of processing the image data from each of sub-arrays of the array of electric field sensing pixels. The electronic device may also include a dielectric layer over the array of electric field sensing pixels and causing electric field diffusion so that the image data output circuitry generates image data corresponding to a blurred finger image. The electronic device also includes deblurring circuitry coupled to the image data output circuitry and capable of processing the image data from each of the plurality of sub-arrays of the array of electric field sensing pixels to produce processed image data representative of a deblurred finger image.