Light Guide Plate Layout for Uniform Fingerprint and Vein Illumination
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Solution Overview
Problem
Optical sensors face issues with insufficient illumination of light emitted from the front light, leading to reduced detection accuracy in fingerprint and vein pattern recognition.
Innovation Solution
A detection device with a light guide plate and multiple light sources emitting different wavelengths, combined with scattering portions and an optical filter layer to enhance light distribution and improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single front light is used for illumination, then the device structure is simple, but the illumination intensity and uniformity are insufficient
Solution Approach 1:
The front light is divided into multiple independent light sources (first light source, second light source, third light source) positioned at different locations. Each light source emits light in different directions to illuminate the detection area from multiple angles, thereby increasing overall illumination intensity and improving uniformity without requiring a single complex high-intensity source
Solution Approach 2:
Multiple light sources with different wavelengths (visible light and infrared light) are combined in a single illumination system. The light guide plate integrates these different wavelength lights and directs them through the same detection area, achieving comprehensive illumination that enhances both intensity and provides multiple wavelength options for different detection needs
2Measurement precision
If multiple light sources with different wavelengths are used, then detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The light guide plate is designed to handle multiple wavelengths (visible and infrared) simultaneously through a single structure. The same light guide plate that guides visible light from the first and second light sources also guides infrared light from the third light source, making the illumination system multi-functional without requiring separate guidance structures for each wavelength
Solution Approach 2:
The light guide plate serves as an intermediary component that receives light from multiple different wavelength sources and distributes it uniformly across the detection area. This mediator structure simplifies the overall system by providing a single interface for multiple light sources rather than requiring separate illumination paths for each wavelength
3Illumination intensity
If light guide paths are provided for multiple wavelengths, then illumination uniformity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses light sources with different wavelengths (visible and infrared) as a parameter change strategy. By selecting light sources and optical materials that are compatible across these wavelengths, the system achieves multi-wavelength illumination uniformity without requiring different optical paths for each wavelength, thereby reducing manufacturing precision requirements
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
The device achieves improved detection accuracy by ensuring optimal light illumination and reducing stray light, enhancing the ability to detect fingerprint and vein patterns.
Implementation Method 1
a plurality of scattering portions that are provided on the light guide plate and configured to scatter light from any of the first light source, the second light source, and the third light source
Implementation Method 2
a plurality of photodiodes arranged on a substrate
Data Source
AI summary
According to an aspect, a detection device includes: photodiodes arranged on a substrate; and a front light comprising a light guide plate disposed so as to overlap the photodiodes, a first light source configured to emit first light to a first side surface of the light guide plate, a second light source configured to emit second light having the same wavelength as that of the first light to a second side surface of the light guide plate opposite to the first side surface, a third light source configured to emit third light having a wavelength different from that of the first light to a third side surface of the light guide plate different from the first and second side surfaces, and scattering portions provided on the light guide plate and configured to scatter light from any of the first light source, the second light source, and the third light source.