Optical Sensing Element With Stacked Light Shields for Fingerprint Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical fingerprint sensing devices struggle with accurate fingerprint recognition under strong ambient light conditions due to excessive exposure of the image signal, leading to reduced sensing performance.
Innovation Solution
An electronic device design incorporating a substrate, multiple light-shielding layers with non-overlapping openings, and a microlens configuration that maximizes response to oblique incident light within a specific angle range, reducing ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the optical sensing element is exposed to strong ambient light, then the sensing area is maximized, but the image signal becomes excessively exposed and fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent divides the light-shielding function into multiple separate light-shielding layers (first, second, and third light-shielding layers) positioned at different heights. Each layer blocks light from specific angles, collectively creating a comprehensive light-shielding effect that prevents ambient light overexposure while maintaining the sensing element's area.
Solution Approach 2:
The patent introduces a vertical dimension to light-shielding by positioning light-shielding layers at different heights (first light-shielding layer closest to the sensing element, second layer in the middle, third layer furthest). This three-dimensional arrangement blocks light from multiple angles simultaneously, solving the ambient light interference problem without reducing the sensing area.
2Measurement precision
If multiple light-shielding layers are added to block ambient light, then fingerprint recognition accuracy under strong light improves, but device structural complexity increases
Solution Approach 1:
The light-shielding function is segmented into multiple layers, each handling specific light angles. The first light-shielding layer blocks light from angles closer to the sensing element, the second layer handles intermediate angles, and the third layer blocks light from more oblique angles. This segmentation allows each layer to be simpler individually while the collective system achieves comprehensive light-shielding.
Solution Approach 2:
The light-shielding layers are nested in a stacked arrangement with the sensing element at the base. The first light-shielding layer is positioned closest to the sensing element, with the second and third layers positioned progressively higher. This nested structure efficiently uses space and maintains compact device dimensions while providing multi-angle light-shielding.
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
Enhances sensing performance by minimizing the impact of ambient light, particularly in bright environments, ensuring accurate fingerprint recognition and identification.
Implementation Method 1
a first light-shielding layer disposed on the substrate and having a first opening, a second light-shielding layer disposed on the first light-shielding layer and having a second opening, and a third light-shielding layer disposed on the second light-shielding layer and having a third opening
Implementation Method 2
a microlens configured to maximize a response value of the optical sensing element to oblique incident light within a specific angle range
Data Source
AI summary
An electronic device is provided. The electronic device includes a substrate, a first light-shielding layer, a second light-shielding layer, a third light-shielding layer and an optical sensing element. The first light-shielding layer is disposed on the substrate and has a first opening. The second light-shielding layer is disposed on the first light-shielding layer and has a second opening. The third light-shielding layer is disposed on the second light-shielding layer and has a third opening. The optical sensing element is disposed on the substrate, and overlapped with the first opening. In addition, in a top-view diagram, centers of the first opening, the second opening and the third opening are separated from each other along a first direction, and the first direction is a line connecting a center of the first opening and a center of the third opening.