Under-screen Fingerprint Sensor Light Directing Channels
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Solution Overview
Problem
Current under-screen optical fingerprint identification technologies face challenges in achieving high imaging quality while maintaining thinness and lightness, with existing solutions either requiring deep collimating holes for high imaging quality but low light utilization or using micro lenses that result in signal aliasing and low contrast.
Innovation Solution
A fingerprint identification apparatus combining a micro lens array with multiple pixel units and light shielding layers, where each micro lens corresponds to multiple pixel units receiving oblique collimated light, forming light directing channels to improve contrast and brightness, and the light shielding layers are designed with specific aperture ratios and shapes to optimize light transmission and reduce stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a collimating hole is used for imaging, then imaging quality is improved, but light utilization rate decreases and device thickness increases
Solution Approach 1:
The patent divides the single collimating hole into multiple light guiding channels, each with its own light blocking layer and pixel unit. This segmentation allows light to be collected from multiple directions while maintaining collimation, improving both light utilization and imaging quality without increasing overall device thickness
Solution Approach 2:
The patent introduces intermediate light blocking layers with light passing holes that create light directing channels in oblique directions. By adding this intermediate dimension of light blocking layers between the micro lens array and pixel units, the system can guide light from multiple angles to corresponding pixel units, resolving the contradiction between imaging quality and light utilization
2Loss of energy
If a micro lens is used for focusing, then light utilization rate is improved, but signal aliasing occurs and imaging quality decreases
Solution Approach 1:
The patent introduces intermediate light blocking layers as mediators between the micro lens array and pixel units. These intermediate layers with light passing holes prevent direct light from causing aliasing while still allowing collimated light to reach the pixel units, thus eliminating signal aliasing while maintaining high light utilization rate
Solution Approach 2:
The patent applies different functions to different parts of the optical system: the micro lens array focuses light efficiently, while the intermediate light blocking layers with light passing holes selectively block or transmit light based on direction. This local differentiation of functions resolves the aliasing problem while preserving the high light utilization rate of micro lenses
3Measurement precision
If the depth of collimating hole is increased, then imaging quality is improved, but device thickness increases
Solution Approach 1:
Instead of increasing the depth of collimating holes in the vertical direction, the patent introduces intermediate light blocking layers that create light directing channels in oblique directions. This dimensional approach allows achieving high imaging quality without increasing overall device thickness
Solution Approach 2:
The patent segments the light path into multiple channels with intermediate light blocking layers at different depths, allowing light to be guided from multiple directions to corresponding pixel units. This segmentation enables high imaging quality to be achieved through multiple shallow layers rather than one deep hole, reducing overall device thickness
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 design enhances image contrast and brightness, improves fingerprint identification accuracy, and reduces the thickness of the fingerprint identification apparatus, effectively addressing the limitations of existing technologies.
Implementation Method 1
each micro lens corresponds to multiple pixel units receiving oblique collimated light
Implementation Method 2
A fingerprint identification apparatus combining a micro lens array with multiple pixel units and light shielding layers, where each micro lens corresponds to multiple pixel units receiving oblique collimated light
Implementation Method 3
the light shielding layers are designed with specific aperture ratios and shapes to optimize light transmission and reduce stray light
Data Source
Figure 1~2
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Figure 5
AI summary
Embodiments of the present application disclose a fingerprint identification apparatus and an electronic device. The fingerprint identification apparatus includes a plurality of fingerprint identification units distributed in an array, and each of the plurality of fingerprint identification units includes: a plurality of pixel units; a micro lens disposed above the plurality of pixel pixels; and a plurality of light shielding layers disposed between the micro lens and the plurality of pixel units, where each of the plurality of light shielding layers is provided with light passing holes corresponding to the plurality of pixel units so as to from a plurality of light directing channels in one-to-one correspondence with the plurality of pixel units; where the plurality of light shielding layers include a bottom light shielding layer and an intermediate light shielding layer, the intermediate light shielding layer includes a light shielding layer other than the bottom light shielding layer, a light passing aperture D2 of a light passing region formed by light passing holes in the intermediate light shielding layer that are corresponding to the plurality of pixel units and a maximum aperture CA of the micro lens satisfy 0.3≤D2/CA≤1.3, and D2 is a distance between two farthest points in the light passing region on a plane where the intermediate light shielding layer is located.