Optical Fingerprint Sensor Pixel Layout for Anti-Counterfeiting
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Solution Overview
Problem
Conventional optical fingerprint sensors are susceptible to counterfeiting due to their inability to sense color images and lack of special positioning codes or patterns, which compromises their security and accuracy in fingerprint recognition.
Innovation Solution
The integration of positioning pixels and color pixels into the pixel array of an optical fingerprint sensor (OFPS) to add fingerprint positioning codes and skin tone codes, respectively, enhancing the anti-counterfeiting capabilities of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fingerprint sensors use only grayscale pixels, then the device complexity is reduced and manufacturing is easier, but the anti-counterfeiting capability and security are compromised
Solution Approach 1:
The pixel array is segmented into three distinct types of pixels: grayscale pixels for capturing fingerprint ridge-valley patterns, color pixels for detecting skin tone information, and positioning pixels for providing reference markers. This segmentation allows each pixel type to perform its specialized function, enhancing anti-counterfeiting capability while maintaining manageable complexity through clear functional division.
Solution Approach 2:
The sensor employs a composite pixel array structure that integrates multiple pixel types (grayscale, color, and positioning pixels) within a single array. This composite approach combines the advantages of different pixel types to achieve both security enhancement through multi-modal fingerprint data and structured complexity management through systematic integration.
2Reliability
If positioning pixels and color pixels are added to the pixel array, then the anti-counterfeiting capability is enhanced, but the manufacturing precision and alignment requirements increase
Solution Approach 1:
Positioning pixels are pre-distributed in a known regular pattern across the pixel array before fingerprint capture. These positioning pixels serve as predetermined reference markers that establish a coordinate system, enabling the system to compensate for minor alignment variations and facilitate accurate registration of fingerprint data without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The positioning pixels provide feedback reference points that enable the system to detect and correct for alignment deviations. By comparing the expected positions of positioning pixels with their actual detected positions, the system can identify and compensate for manufacturing variations, thereby maintaining security levels despite relaxed precision requirements.
3Measurement precision
If multiple types of pixels are integrated, then the fingerprint recognition accuracy is improved, but the device complexity and processing requirements increase
Solution Approach 1:
The processing of multi-type pixel data is segmented into distinct stages: positioning pixels are processed first to establish reference coordinates, then color pixels are processed to extract skin tone information, and finally grayscale pixels are processed to capture fingerprint patterns. This segmented processing approach improves recognition accuracy through comprehensive data analysis while managing complexity through systematic task division.
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 addition of positioning and color pixels significantly enhances the anti-counterfeiting capabilities of the OFPS by making it difficult to rebuild a fingerprint image from a hacked or leaked minutia map, thereby improving the security and accuracy of fingerprint recognition.
Implementation Method 1
The array of photodiodes is arranged under the array of light filters, and each photodiode is configured to accumulate charge from photons incident on the photodiode
Data Source
AI summary
An image sensing apparatus is disclosed. The image sensing apparatus includes a pixel array and micro lenses disposed above the pixel array. The pixel array includes sensing pixels configured to capture minutia points of a fingerprint and positioning pixels configured to provide positioning codes.