Optical Fingerprint Sensor with Varying Pixel Integration Times
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Solution Overview
Problem
Optical fingerprint systems face challenges in balancing reliability and security with processing time and power consumption, particularly when capturing and authenticating large or high-resolution images, which can lead to increased latency and resource wastage.
Innovation Solution
The system employs varying integration times across pixels, allowing the sensor to capture and authenticate blocks of pixels in parallel, with additional blocks captured and evaluated if initial authentication fails, thereby minimizing latency and power consumption while ensuring detailed image analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor captures and analyzes large or high-resolution images to improve reliability and security, then authentication accuracy is improved, but processing time and power consumption increase
Solution Approach 1:
The patent divides the fingerprint image into multiple blocks and processes them in stages. The sensor captures blocks sequentially with increasing integration times, allowing the system to authenticate using smaller subsets of blocks rather than waiting for complete high-resolution image capture. This segmentation enables early authentication decisions without processing the entire large image, reducing overall processing time while maintaining security through progressive detail analysis.
Solution Approach 2:
The system performs preliminary authentication attempts using blocks captured with shorter integration times before completing the full high-resolution capture. By attempting authentication with preliminary, lower-detail blocks first, the system can quickly reject obvious mismatches without incurring the full processing cost of high-resolution analysis, thereby reducing average processing time while preserving security for genuine matches.
2Reliability
If the sensor captures and analyzes large or high-resolution images to improve reliability and security, then authentication accuracy is improved, but power consumption increases
Solution Approach 1:
The patent segments the authentication process into multiple stages using different blocks with varying integration times. By processing blocks in stages and potentially authenticating before completing full high-resolution capture, the system avoids the excessive power consumption of always capturing and processing complete high-resolution images, while still maintaining security through progressive detail analysis when needed.
Solution Approach 2:
The system performs partial authentication using only the necessary subset of blocks with appropriate integration times for each authentication attempt. Rather than always capturing complete high-resolution images with maximum integration times, the system uses partial block sets with tailored integration durations, consuming only the power necessary for each specific authentication case while maintaining security through selective detail analysis.
3Measurement precision
If the sensor uses longer integration times to capture more detail, then image quality is improved, but latency increases
Solution Approach 1:
The patent segments the image capture into multiple blocks with different integration times. The sensor captures blocks sequentially, with each block using integration time optimized for its specific authentication purpose. This allows the system to use shorter integration times for blocks that don't require high detail, while applying longer integration times only to specific blocks where additional detail is necessary for authentication, thereby reducing overall latency while maintaining image quality where needed.
Solution Approach 2:
The system applies different integration times to different blocks based on their specific authentication requirements. Rather than using a uniform long integration time for all blocks, the patent implements local quality by tailoring integration duration to each block's needs, using shorter times for blocks where high precision isn't critical and longer times only where additional detail improves authentication accuracy, thus minimizing overall latency while preserving necessary image quality.
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 enables efficient authentication of large or high-resolution images with reduced latency and power usage, maintaining high security and reliability without compromising user experience.
Implementation Method 1
The sensor collects light, which reflects off the user input and back under the screen
Implementation Method 2
The sensor collects light... integrating the light reflected by the input, the sensor generates an image
Data Source
AI summary
Described is an optical fingerprint system with varying integration times across pixels. A sensor selects blocks of pixels contacted or covered by an input to a region of a display. While a matcher attempts to authenticate the input with first blocks of pixels captured by the sensor, the sensor captures additional blocks of pixels for subsequent authentication if the first blocks fail. With more time to integrate the light reflected off the input, each additional block of pixels include more detail than previously captured blocks. If authentication fails based on the first blocks, the matcher can reattempt authentication using the additional blocks without delay. Repeating this process enables the system to authenticate input using very large or high-resolution images while minimizing latency and power consumed to authenticate the input.