Biometric Device Optical Angular Selecting Structure
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Solution Overview
Problem
Conventional biometric devices for fingerprint and finger vein recognition face challenges in achieving compact size and high accuracy due to the need for large lenses to converge light effectively, leading to issues with light divergence and low resolution images, which complicates their integration into portable electronic devices.
Innovation Solution
A biometric device with an optical angular selecting structure comprising a micro lens array, refractive layer, and light shielding layer, where specific conditions are met to control the aspect ratio and optical angular selective distance, reducing crosstalk and allowing only light with appropriate angles to reach the sensing units, thereby enhancing image quality and device compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lens is used to converge light from the finger onto the sensors, then light convergence is achieved, but the device size becomes large
Solution Approach 1:
The patent divides the single large lens into multiple small lens units arranged in an array. Each lens unit corresponds to a specific sensing unit and converges light only from its corresponding region, eliminating the need for a large lens while maintaining light convergence capability. This segmentation allows compact device design without sacrificing optical performance.
Solution Approach 2:
The patent transitions from a single-point optical convergence approach to a multi-point array approach by distributing multiple lens units across the sensing array. This dimensional expansion from 1D (single lens) to 2D (lens array) enables compact integration while preserving light convergence functionality for each sensing element.
2Volume of moving object
If the lens is removed to reduce device size, then device compactness is improved, but light received by the sensors becomes insufficient
Solution Approach 1:
The patent replaces the single large lens with multiple small lens units, each responsible for collecting and converging light for its corresponding sensing unit. This segmentation ensures that each sensing element receives sufficient light intensity while the overall device remains compact, as each small lens unit is much smaller than the original large lens.
3Quantity of substance
If light reflected by biological characteristics is allowed to reach multiple sensors, then light collection is maximized, but image resolution becomes low due to crosstalk
Solution Approach 1:
The patent segments the optical path by assigning each lens unit to a specific sensing unit, creating dedicated light collection channels. This segmentation prevents crosstalk between adjacent sensors while maintaining efficient light collection for each sensing element, thereby preserving both light collection efficiency and image resolution.
Solution Approach 2:
The patent implements local quality control by ensuring that each lens unit collects light only from its corresponding local region and directs it to the corresponding sensing unit. This local optimization prevents light from one region from interfering with adjacent sensing units, eliminating crosstalk while maintaining high light collection efficiency for each local channel.
4Measurement precision
If a light passing part with high aspect ratio is formed to prevent light divergence, then point-to-point imaging is achieved, but manufacturing difficulty increases
Solution Approach 1:
The patent segments the light passing structure into multiple small openings in the light shielding layer, each corresponding to a lens unit and sensing unit pair. This segmentation reduces the aspect ratio requirement for each individual opening compared to a single large opening, making manufacturing more feasible while maintaining point-to-point imaging capability through the array of segmented paths.
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 solution effectively reduces crosstalk and improves image resolution, enabling high-accuracy biometric recognition while maintaining a compact device size, as demonstrated by the satisfaction of specific conditions that ensure light with large angles is blocked or directed to non-sensing regions, resulting in high-resolution biometric images.
Implementation Method 1
The optical angular selecting structure includes a micro lens array, a refractive layer and a light shielding layer. The refractive layer is disposed between the micro lens array and the light shielding layer.
Implementation Method 2
the light shielding layer defines a plurality of light passing parts... allowing only light with appropriate angles to reach the sensing units, thereby enhancing image quality and device compactness
Data Source
AI summary
A biometric device includes an illuminating unit and an imaging module. The imaging module includes an optical angular selective structure and a sensing layer. The light selecting structure includes a micro lens array, a refractive layer and a light shielding layer. The refractive layer is disposed between the micro lens array and the light shielding layer. The micro lens array includes a plurality of lens unit units, and the light shielding layer has a plurality of light passing portions. The sensing layer defines multiple sensing regions which are spaced apart from each other. The light shielding layer is disposed between the refractive layer and the sensing layer. The sensing regions correspond to the light passing portions, respectively. An optical angular selective distance is defined between the light shielding layer and the sensing layer.