Optical Fingerprint Display Scanning Using Orthogonal Vector Demodulation
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Solution Overview
Problem
Optical fingerprint recognition technologies face challenges due to afterglow interference and ambient light interference, leading to low accuracy in fingerprint information obtained, which affects recognition performance.
Innovation Solution
A method using mutually orthogonal or quasi-orthogonal data vectors to control light emission in a fingerprint recognition area, reducing interference between pixel units and improving the accuracy of fingerprint information obtained through demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If self-emitting light of pixels is used to illuminate the finger, then the fingerprint recognition system can be integrated into the terminal display, but afterglow interference and ambient light interference occur, reducing the accuracy of fingerprint information
Solution Approach 1:
The patent applies periodic action by sequentially turning on different groups of pixels in multiple scanning rounds. In each round, only specific pixel groups (e.g., even rows in odd rounds, odd rows in even rounds) are activated to emit light. This periodic illumination pattern allows the system to integrate fingerprint recognition into the display while reducing interference through time-separated measurements and subsequent signal processing to extract accurate fingerprint information.
2Illumination intensity
If multiple pixels emit light simultaneously, then the illumination coverage is sufficient, but mutual interference between pixel lights causes afterglow interference
Solution Approach 1:
The patent segments the pixel array into multiple groups that are activated sequentially rather than simultaneously. Different pixel groups are turned on in different scanning rounds, with each group covering specific row ranges. This segmentation in time and space allows sufficient overall illumination coverage while preventing mutual interference between simultaneously emitting pixels, as only one group emits light at any given moment.
3Adaptability or versatility
If the photoelectric detector receives ambient light, then the detector can function in various lighting conditions, but strong ambient light causes interference to the optical fingerprint signal
Solution Approach 1:
The patent employs feedback through multiple scanning rounds and signal processing to distinguish the fingerprint signal from ambient light interference. By sequentially illuminating different pixel groups and measuring the reflected light multiple times, the system can differentiate between the modulated fingerprint signal and the constant ambient light background, thereby maintaining measurement precision across various lighting conditions.
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 method enhances the accuracy of fingerprint information and improves fingerprint recognition performance by minimizing mutual interference between light-emitting pixel units.
Implementation Method 1
the PD receives an optical signal reflected by a surface of the finger, converts the optical signal into an electrical signal
Data Source
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AI summary
Embodiments of this application disclose a terminal display scanning method for optical fingerprint recognition to improve optical fingerprint recognition performance. The method in this application includes: if a start operation on a terminal screen is detected, obtaining a first vector set, where the first vector set includes A data vectors that are mutually orthogonal or mutually quasi-orthogonal, each of the data vectors includes a plurality of data elements, and A is an integer greater than 1; sequentially using the data elements in each of the data vectors to control light emitting of minimum pixel units in a fingerprint recognition area until controlling light emitting of all the minimum pixel units in the fingerprint recognition area is completed, to obtain a second vector set corresponding to the fingerprint recognition area, where the second vector set carries fingerprint information; and demodulating the second vector set by using the first vector set to obtain all fingerprint information in the fingerprint recognition area.