Under-display Collimator for Moiré Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Under-display fingerprint sensors face challenges in achieving high resolution and compact design due to moiré patterns and alignment issues, which affect the manufacturing cost and image quality.
Innovation Solution
A collimator with a substrate, microlens array, and aperture array is used to focus light from a fingerprint surface onto an image sensor, allowing for a compact design and suppressing moiré patterns by limiting the field of view of each microlens, thus enabling high-resolution fingerprint imaging without requiring precise alignment with the image sensor pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an optical fingerprint sensor is positioned underneath the smartphone display, then the display area can be maximized, but moiré patterns interfere with image quality
Solution Approach 1:
The collimator lens is divided into multiple zones, with each zone corresponding to a specific region of the fingerprint sensor array. Each zone limits the field of view to collect light only from its corresponding sensor region, preventing moiré patterns caused by full-lens capture of display pixel patterns
Solution Approach 2:
Different zones of the collimator lens have different optical properties tailored to their specific functions. Each zone is optimized to capture light from its corresponding fingerprint sensor region, creating local optical quality variations that eliminate moiré interference while maintaining overall imaging performance
2Measurement precision
If a traditional imaging lens is used, then high-resolution imaging can be achieved, but the device complexity and alignment precision requirements increase
Solution Approach 1:
The imaging system is segmented into multiple independent lens zones, each serving a specific sensor region. This segmentation simplifies the optical path for each zone and reduces the overall alignment complexity compared to a single traditional imaging lens
Solution Approach 2:
The collimator lens acts as an intermediary optical element between the fingerprint sensor and the image sensor. It pre-processes the light by limiting fields of view and creating simplified optical paths, making the subsequent imaging process less complex and more tolerant to alignment variations
3Volume of moving object
If a compact design is implemented, then the device size is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The collimator lens is segmented into multiple zones with simplified optical paths for each zone. This segmentation allows for compact overall design while reducing the manufacturing precision requirements compared to a single complex imaging lens, as each zone can be independently optimized and aligned
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 solution allows for high-resolution fingerprint imaging with reduced manufacturing costs and effective suppression of moiré patterns, enabling compact device designs suitable for smartphones and tablets.
Implementation Method 1
an array of microlenses disposed on the first surface for focusing light from a fingerprint surface onto a focal plane
Implementation Method 2
an array of apertures between the array of microlenses and the substrate, wherein each of the apertures is aligned to and cooperates with a respective one of the microlenses to form a field-of-view-limited lens
Data Source
AI summary
A collimator for under-display fingerprint sensing includes (a) a substrate having opposite facing first and second sides, (b) an array of microlenses disposed on the first surface for focusing light from a fingerprint surface onto a focal plane that is between the array of microlenses and the second side of the substrate such that the light, as projected by the array of microlenses, is diverging when exiting the second side of the substrate, and (c) an array of apertures between the array of microlenses and the substrate, wherein each of the apertures is aligned to and cooperates with a respective one of the microlenses to form a field-of-view-limited lens having a field of view corresponding to a respective local portion of the fingerprint surface.