Collimator Filter Layer for Optical Fingerprint Sensing
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Solution Overview
Problem
Conventional optical fingerprint sensors are too bulky for integration in mobile devices, struggling to detect fine ridge and valley features through thick cover glass, requiring mechanical buttons and cutouts that compromise device design and functionality.
Innovation Solution
Integration of image sensor structures with collimator filters, where a collimator filter layer with light collimating apertures is formed on an image sensor wafer, allowing for optical sensing through thick cover layers without blurring, enabling a lower-profile sensor suitable for mobile devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fingerprint sensors are used, then optical sensing capability is achieved, but the sensor becomes too bulky for mobile device integration
Solution Approach 1:
The optical sensor is divided into separate functional layers: a collimator filter layer with aperture array positioned above the image sensor array. This segmentation allows each layer to be optimized independently and enables thin-profile integration in mobile devices while maintaining optical sensing capability through the separation of light conditioning and detection functions
Solution Approach 2:
The collimator filter layer is positioned in a dimension above the image sensor array, creating a layered vertical structure. This dimensional arrangement allows the light collimation function to be separated from the detection plane, enabling thin-profile integration while preserving optical sensing performance through spatial separation of functions
2Reliability
If conventional optical sensors sense through thick cover glass, then fingerprint detection is attempted, but image blurring occurs due to difficulty sensing fine ridge and valley features
Solution Approach 1:
The collimator filter layer acts as an intermediary between the thick cover glass and the image sensor array. The aperture array in this intermediate layer conditions the light paths, allowing fine ridge and valley features to be resolved through thick cover glass without image blurring by filtering out oblique light rays that would otherwise cause degradation
Solution Approach 2:
The collimator filter layer provides localized light conditioning at each aperture position, creating region-specific optical paths optimized for resolving fine fingerprint features. Each aperture acts as a local optical element that maintains image clarity by controlling light collection angles specific to its position in the array
3Reliability
If capacitive sensors with cutouts are used, then fingerprint sensing through cover glass is avoided, but device design is compromised and manufacturing is complicated
Solution Approach 1:
The optical sensor with collimator filter layer provides universal functionality that eliminates the need for separate cutout arrangements. The sensor can be integrated into the display assembly without requiring mechanical buttons or cutouts, as the optical design inherently enables fingerprint sensing through the display cover glass, simplifying both device structure and manufacturing
Solution Approach 2:
The fingerprint sensor is merged with the display assembly, with the collimator filter layer and image sensor array integrated into the display structure. This combination eliminates the need for separate cutout areas and mechanical buttons, creating a unified flush surface that simplifies device design and manufacturing while maintaining fingerprint sensing capability
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
Enables reliable optical fingerprint sensing through thick cover layers, improving sensitivity and reducing device thickness, thus enhancing user experience and manufacturing efficiency by eliminating the need for mechanical buttons and cutouts.
Implementation Method 1
forming a collimator filter layer on an image sensor wafer, wherein a plurality of light collimating apertures in the collimator filter layer are aligned with a plurality of light sensing elements in the image sensor wafer
Data Source
AI summary
Methods and systems for integrating image sensor structures with collimator filters, including manufacturing methods and associated structures for forming collimator filters at the wafer level for integration with image sensor semiconductor wafers. Methods of making an optical biometric sensor include forming a collimator filter layer on an image sensor wafer, wherein a plurality of light collimating apertures in the collimator filter layer are aligned with a plurality of light sensing elements in the image sensor wafer, and after forming the collimator filter layer on the image sensor wafer, singulating the image sensor wafer into a plurality of individual optical sensors.