Optical Fingerprint Sensor With Multi-Spectral Groove Detection
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Solution Overview
Problem
Existing under-screen optical fingerprint sensors struggle to distinguish between real and false fingerprints, as they rely solely on visible light, which can result in false identifications due to similar reflectivity patterns.
Innovation Solution
The optical fingerprint sensor incorporates a light-sensing element with grooves for visible light and an additional layer for invisible light, combined with an optical filter and lens, allowing for the emission and detection of invisible light near the red spectrum to differentiate between real and false fingerprints based on unique spectral reflection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only visible light is used for fingerprint sensing, then the device structure is simple, but the ability to distinguish real from false fingerprints is insufficient
Solution Approach 1:
The light-sensing element is segmented into multiple independent light-sensing layers, each sensitive to different wavelength ranges (visible and invisible light). This segmentation allows the sensor to capture spectral information from different wavelength bands separately, enabling differentiation between real and false fingerprints through multi-spectral analysis while maintaining a modular structure that doesn't excessively increase device complexity
Solution Approach 2:
The patent transitions from single-wavelength (visible light only) to multi-wavelength (visible + invisible light) sensing by adding another dimension of spectral detection. This dimensional expansion in the wavelength domain provides additional discriminatory information for fingerprint authentication without requiring complex mechanical or structural changes to the overall sensor design
2Measurement precision
If multiple light-sensing layers are added to detect both visible and invisible light, then the spectral detection capability is improved, but the device structure becomes more complex
Solution Approach 1:
Multiple light-sensing layers detecting different wavelength ranges are merged into a single integrated light-sensing element structure. This merging combines the visible light sensing and invisible light sensing capabilities in one unified component, achieving precise multi-spectral detection while avoiding the complexity of separate sensing systems. The layered structure is integrated at the material level rather than requiring separate mechanical assemblies
Solution Approach 2:
The light-sensing element employs composite material structures with different layers having distinct spectral sensitivity characteristics. By using composite materials with tailored optical properties for each layer, the sensor achieves precise detection across multiple wavelength ranges while maintaining a compact, integrated structure that doesn't excessively increase device complexity
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 approach enhances the security of electronic devices by effectively distinguishing real from false fingerprints through improved imaging resolution and authenticity verification, reducing false identification rates.
Implementation Method 1
The light emitted by the display panel reaches a surface of a finger through the glass cover plate. Due to different reflectivity of the light at a ridge or a valley of the fingerprint, intensities of the light reflected at the ridge or the valley of the fingerprint are also different.
Implementation Method 2
a second light-sensing layer for receiving invisible light, the second light-emitting layer being arranged between an inner wall surface of at least part of the plurality of grooves and an outer wall surface of the first light-sensing layer
Implementation Method 3
an optical lens for focusing
Data Source
AI summary
An optical fingerprint sensor and an electronic device having same are provided. The optical fingerprint sensor includes a light-sensing element, an optical filter layer and an optical lens. The light-sensing element includes: a light-sensing base layer having a groove in a side surface thereof; a first light-sensing layer configured to receive visible light and arranged in the groove; and a second light-sensing layer configured to receive invisible light, and arranged between an inner wall surface of the groove and an outer wall surface of the first light-sensing layer. The optical filter layer is stacked on a side of the light-sensing element where the groove is formed. The optical lens is configured for focusing and stacked on a side of the optical filter layer facing away from the light-sensing element.