Transparent Cover Waveguide for High-Resolution Fingerprint Detection
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Solution Overview
Problem
Existing fingerprint detection technologies in electronic devices face challenges in achieving high resolution and thin form factors due to the thickness of the transparent cover, which leads to blurring and increased component complexity, especially in portable devices.
Innovation Solution
The use of a transparent cover as a waveguide combined with a filter layer, such as a fiber optic faceplate or filter film, that selectively allows narrow-angle light rays to reach the detector, reducing blurring and enabling thinner, more scalable fingerprint sensors compatible with various device form factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional fingerprint sensor with separate components is used, then fingerprint detection function is achieved, but device thickness increases and resolution decreases due to blurring
Solution Approach 1:
The patent combines the transparent cover and the fingerprint sensor into a single integrated structure. The transparent cover serves dual purposes as both the display protective layer and the fingerprint sensing element, eliminating the need for separate components and reducing overall device thickness while maintaining detection resolution
Solution Approach 2:
The transparent cover is designed to perform multiple functions simultaneously: it acts as the display module's protective cover, serves as the waveguide for light propagation, and functions as the fingerprint sensor. This multi-functionality reduces component count and enables thinner device design without compromising fingerprint detection capability
2Strength
If the transparent cover thickness is increased, then structural strength is improved, but light scattering increases causing blurring and reduced detection resolution
Solution Approach 1:
The patent optimizes the thickness parameter of the transparent cover to a specific range that balances mechanical strength and optical performance. By carefully selecting the thickness parameter, the design achieves sufficient structural strength while minimizing light scattering and maintaining high fingerprint detection resolution
Solution Approach 2:
The transparent cover is designed as a composite structure with specific material properties that optimize both mechanical strength and optical clarity. The material composition is selected to provide adequate strength while maintaining low light scattering characteristics for high-resolution fingerprint detection
3Reliability
If separate fingerprint sensor components are used, then detection function is achieved, but device complexity and component quantity increase
Solution Approach 1:
The patent merges the fingerprint sensor functionality into the transparent cover itself, eliminating the need for separate sensor components. The transparent cover contains the necessary sensing elements and structures directly integrated within it, reducing component quantity while maintaining reliable fingerprint detection function
Solution Approach 2:
The transparent cover is designed as a multi-functional component that simultaneously provides display protection, light guidance, and fingerprint sensing capabilities. This integration reduces the overall component quantity and simplifies device architecture while ensuring reliable fingerprint detection functionality
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 solution enhances fingerprint detection resolution, reduces blurring, and simplifies device design by integrating the fingerprint sensor with the display module, allowing for thinner, more versatile, and efficient fingerprint detection systems in diverse electronic devices.
Implementation Method 1
The transparent cover guides light until interaction with a fingerprint ridge
Implementation Method 2
A filter layer is disposed along the rear face of the transparent cover. The filter layer is configured to selectively allow narrow-angle light rays scattered by the fingerprint ridge to reach the detector
Data Source
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AI summary
An electronic device includes a transparent cover and a light source disposed at an edge of the transparent cover. The light source is configured to inject light into the transparent cover. The transparent cover guides the light until interaction with a fingerprint ridge at the transparent cover. The electronic device further includes a filter disposed along the transparent cover. The filter is configured to selectively allow the light scattered by the fingerprint ridge to pass through the filter. A detector generates a signal indicative of the scattered light allowed through the filter.