Optical Fingerprint Sensor Parallel Integration Time Selection
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Solution Overview
Problem
Conventional auto exposure methods for optical fingerprint recognition systems are inefficient in quickly determining the proper integration time, leading to prolonged processing times for determining the correct fingerprint image in varying ambient light conditions.
Innovation Solution
The method involves scanning multiple groups of sensing pixels with different integration times in parallel to rapidly determine the optimal integration time, allowing the system to then use this selected time for capturing image data, thereby reducing the overall time required for integration time determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional auto exposure method is used to determine proper integration time by scanning several image frames, then the integration time can be accurately determined, but the time required for determination is too long
Solution Approach 1:
The sensing pixels are divided into multiple groups, with each group assigned a different integration time. By scanning these groups simultaneously in parallel, the system determines the proper integration time much faster than conventional sequential methods, reducing determination time from 6T to 3T while maintaining accuracy
Solution Approach 2:
The patent performs preliminary scanning of multiple pixel groups with different integration times before final image capture. This preliminary action allows the system to pre-determine the optimal integration time based on ambient light conditions, enabling faster subsequent imaging without requiring multiple trial scans
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 significantly reduces the time needed to determine the proper integration time, from conventional methods' 6T to 3T, enhancing the speed and efficiency of fingerprint recognition processes.
Implementation Method 1
the optical fingerprint sensor needs to find out a proper integration time (also called exposure time) for each received fingerprint image
Data Source
AI summary
The present invention provides a method of obtaining image data for an image sensing system. The image sensing system includes a sensing area having a plurality of sensing pixels. The method includes the steps of: scanning at least two groups of sensing pixels among the plurality of sensing pixels with at least two integration times, respectively, to obtain a plurality of sensing results; obtaining a selected integration time from one of the at least two integration times according to the plurality of sensing results; and scanning the plurality of sensing pixels except for the at least two groups of sensing pixels with the selected integration time, to obtain the image data.