Fingerprint Sensor Under Thin Face-Sheet Aperture Layer
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Solution Overview
Problem
Existing input devices struggle to effectively combine proximity sensing and fingerprint sensing functionalities in a single module, often requiring separate sensing regions and technologies, which complicates design and usability.
Innovation Solution
The input device integrates a glass cover layer, a printed circuit board with a cavity for the fingerprint sensor, and distinct adhesive layers for fingerprint and proximity sensing areas, allowing for a combined sensing module with improved assembly and signal-to-noise ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate sensing regions and technologies are used for proximity sensing and fingerprint sensing, then each sensing function can be optimized independently, but the device complexity and design difficulty increase
Solution Approach 1:
The patent combines proximity sensing and fingerprint sensing into a single integrated module. The sensing layer includes both proximity sensing regions and fingerprint sensing regions that share common structural elements (substrate, adhesive layers, cover layer), allowing both functions to coexist in one device while maintaining their respective optimization
Solution Approach 2:
The sensing layer is designed to perform multiple functions simultaneously - it serves as both the proximity sensing element and the fingerprint sensing element. The same basic structure (substrate, adhesive layers, cover layer) supports both sensing modalities, making the device multi-functional without requiring completely separate systems
2Device complexity
If a single integrated sensing module is used for both proximity and fingerprint sensing, then device complexity is reduced, but achieving adequate signal quality and assembly precision becomes more difficult
Solution Approach 1:
The sensing layer is segmented into distinct proximity sensing regions and fingerprint sensing regions. This segmentation allows each region to be optimized for its specific function while being part of the same integrated structure. The adhesive layers are also segmented - a first adhesive layer for the fingerprint sensor and a second adhesive layer for the proximity sensor - enabling precise positioning and assembly for each sensing type
Solution Approach 2:
Different adhesive layers with potentially different properties are used in different regions of the device. The first adhesive layer is optimized for bonding the fingerprint sensor, while the second adhesive layer is optimized for bonding the proximity sensor. This local differentiation of material properties enables precise assembly and maintains signal quality for both sensing functions within the integrated module
3Length of stationary object
If thin cover layers are used to improve device compactness, then the device becomes more compact and user-friendly, but signal-to-noise ratio for sensing may deteriorate
Solution Approach 1:
The patent uses a composite structure with multiple layers including a substrate, adhesive layers, and a cover layer. This composite material approach allows optimization of each layer's thickness and properties - the cover layer can be made thin for compactness while the adhesive layers and substrate provide the necessary mechanical support and signal transmission properties to maintain adequate signal-to-noise ratio
Data Source
AI summary
An input device for fingerprint sensing and proximity sensing includes a cover layer, where a top surface of the cover layer is configured to provide an input surface for a finger, a substrate having a cavity disposed below the cover layer, and a fingerprint sensor disposed below the cover layer and in the cavity of the substrate. A first adhesive layer is disposed between a top surface of the fingerprint sensor and a bottom surface of the cover layer in a fingerprint sensing area. A second adhesive layer is disposed between a top surface of the substrate and the bottom surface of the cover layer in a proximity sensing area.