Photodiode Detection Layout for Moiré-Resistant Fingerprint Sensing
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Solution Overview
Problem
Existing detection devices face challenges in reducing moiré patterns caused by the arrangement of photodiodes and sub-pixels in display devices, which affects the accuracy of light detection and fingerprint recognition.
Innovation Solution
A detection device is designed with a substrate having photodiodes arranged in a specific direction, overlapped by lenses, and a light-blocking layer with angled and varying openings to prevent moiré patterns by irregularly arranging the lenses and openings relative to the photodiode direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the arrangement direction of photosensors is aligned with the arrangement direction of display device pixels, then the manufacturing and assembly process is simplified, but moiré patterns occur in the incident light affecting detection accuracy
Solution Approach 1:
The patent applies asymmetry by arranging the photosensors at an angle (e.g., 45 degrees) relative to the display device pixel arrangement direction. This asymmetric configuration breaks the periodic alignment that causes moiré patterns, thereby eliminating interference fringes while maintaining manufacturing feasibility through standardized angular offsets.
Solution Approach 2:
The patent introduces a rotational dimension by orienting the photosensor array at an angle different from the display pixel grid. This dimensional transformation from parallel alignment to angular offset arrangement disrupts the moiré pattern formation mechanism while preserving the functional relationship between the two arrays.
2Measurement precision
If multiple openings are provided in the light-blocking layer for each photodiode region, then light focusing is improved, but the structure becomes more complex
Solution Approach 1:
The patent segments the light-blocking layer into multiple openings within each photodiode region, allowing individual light paths to be controlled and focused separately. This segmentation enables precise light focusing onto each photodiode while maintaining a regular, repeatable pattern that does not significantly increase manufacturing complexity.
Solution Approach 2:
The patent applies local quality by providing multiple openings specifically in regions where light focusing is needed, while other regions maintain simpler structures. This localized complexity only where necessary improves light focusing precision without uniformly increasing device complexity across the entire structure.
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 configuration effectively reduces moiré patterns and improves detection accuracy by ensuring that light is properly focused onto the photodiodes, enhancing the detection of fingerprints and other biometric information.
Implementation Method 1
a plurality of lenses provided so as to overlap the photodiodes
Implementation Method 2
a plurality of photodiodes provided to the substrate and arranged in a first direction
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; a plurality of photodiodes provided to the substrate and arranged in a first direction; a plurality of lenses provided so as to overlap the photodiodes; and a light-blocking layer provided between the photodiodes and the lenses and having a plurality of openings. More than one of the openings is provided in each of regions overlapping the respective photodiodes, and an arrangement direction of the openings in each of the regions overlapping the respective photodiodes is at an angle to the first direction.