Transparent Light Guide Layer for Multi-Fingerprint Capture
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Solution Overview
Problem
Existing mobile devices face challenges in capturing high-quality fingerprints of multiple fingers simultaneously without compromising screen brilliance and efficiency, as prior methods suffer from reduced brightness, energy consumption, and limited precision due to additional illumination layers and sensor configurations.
Innovation Solution
A device with a placement surface, touch-sensitive layer, and an LC unit that uses a transparent light guide layer for diffuse and directed illumination, where the optical sensor layer is positioned below the light guide, allowing for simultaneous capture of multiple fingerprints without additional brightness-reducing layers, and energy-efficient operation by activating only the necessary illumination when fingers are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional illumination layers and sensor configurations are added to capture multiple fingerprints simultaneously, then the capture capability is improved, but the screen brilliance is reduced
Solution Approach 1:
The patent merges the display function and fingerprint sensing function into a single integrated structure. The optical sensor layer is positioned behind the light guide layer, allowing both display and sensing to share the same optical path without requiring separate illumination layers, thus maintaining screen brilliance while enabling multi-fingerprint capture
Solution Approach 2:
The light guide layer serves multiple functions: it guides light for display purposes while simultaneously serving as the illumination source for fingerprint capture. The optical sensor layer also serves dual purposes by detecting both display light and fingerprint reflection patterns, eliminating the need for dedicated sensing components that would reduce screen brightness
2Measurement precision
If additional illumination layers are added for fingerprint capture, then the capture precision is improved, but the energy consumption increases
Solution Approach 1:
The system uses the display backlight itself as the illumination source for fingerprint capture. The light guide layer directs the display light onto the fingerprint and collects the reflected light through the same optical path, eliminating the need for separate illumination sources and reducing energy consumption while maintaining capture precision
Solution Approach 2:
The system switches between display mode and fingerprint capture mode by controlling the light guide layer. During fingerprint capture, the display content is temporarily replaced by the fingerprint image, allowing the same light source to serve both purposes at different times rather than requiring simultaneous operation of multiple illumination systems
3Adaptability or versatility
If additional illumination layers and components are added, then the multi-fingerprint capture capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into fewer layers: the light guide layer serves as both display illumination and fingerprint illumination, while the optical sensor layer detects both display output and fingerprint patterns. This merging eliminates the need for separate illumination layers and sensor arrays that would increase structural complexity
Solution Approach 2:
The optical sensor layer is positioned in a different dimensional plane (behind the light guide layer) rather than requiring lateral expansion of the device structure. This allows multi-fingerprint capture across the entire screen surface without adding complex lateral sensor arrays or multiple illumination zones
4Measurement precision
If the optical sensor is positioned closer to the placement surface, then the resolution is improved, but the screen brilliance is reduced due to additional layers
Solution Approach 1:
The optical sensor layer is integrated behind the light guide layer rather than being separated by additional illumination structures. This merging allows the sensor to be positioned optimally close to the placement surface for high resolution while the light guide layer maintains display brightness by efficiently guiding light without requiring extra intermediate layers
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 high-quality, simultaneous capture of multiple fingerprints across the entire screen surface with improved energy efficiency, maintaining screen brilliance and reducing energy consumption by only activating illumination when fingers are present.
Implementation Method 1
utilizing the reflection at a placement surface for the autopodia to generate the recordings of the prints; for example, the principle of frustrated total internal reflection can be used
Implementation Method 2
The reflection at a placement surface for the autopodia is utilized to generate the recordings of the prints
Data Source
AI summary
A device for displaying information and for capture of prints of a plurality of skin areas of human autopodia by means of reflection, comprising: a placement surface for applying the autopodia, a touch-sensitive layer, an LC unit with pixels arranged which are individually controllable by a control unit, an illumination unit with a transparent light-guide-layer body, first and second illumination means, and an optical sensor layer with sensors below the light-guide-layer body. The first illumination means emits diffuse light in a first wavelength range, and the second emits directed light in a predefined angular range and in a second wavelength range. The sensor elements are sensitive to light of the second wavelength range. The pixels are switchable between a state which is transparent to the diffuse light and directed light and a state which is opaque to the diffuse light, and are illuminated by the diffuse light for displaying information.