Photosensitive Unit Optical Waveguide Fingerprint Recognition
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Solution Overview
Problem
The manufacturing of fingerprint recognition display devices is challenging due to the need for cutting openings in the cover plate, which can lead to rupture and increased difficulty in the manufacturing process.
Innovation Solution
A photosensitive unit comprising a light-emitting structure, a photoelectric converter, an optical waveguide device, and a collimator, where the collimator screens and collimates light rays to ensure they are incident within a specific direction, allowing the optical waveguide device to guide these rays to the photoelectric converter, reducing the need for openings in the cover plate and improving manufacturing ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an opening is cut in the cover plate to place photodiodes, then the distance between photodiodes and finger is reduced improving fingerprint recognition accuracy, but the cover plate becomes prone to rupture and manufacturing difficulty increases
Solution Approach 1:
The patent introduces an optical waveguide device as an intermediary component between the cover plate and photodiodes. The waveguide transmits light from the finger through total internal reflection to the photodiodes, eliminating the need to cut openings in the cover plate while maintaining close optical coupling for accurate fingerprint recognition
Solution Approach 2:
The patent replaces the mechanical approach of cutting physical openings in the cover plate with an optical transmission system using waveguides. This substitution allows light to pass through the intact cover plate via optical principles (total internal reflection) rather than requiring physical breaches, thus maintaining structural integrity while achieving optical access
2Manufacturing precision
If an opening is cut in the cover plate, then light scattering is reduced improving recognition accuracy, but the manufacturing process becomes more complex
Solution Approach 1:
The optical waveguide device serves as a mediator that controls light transmission without requiring openings. The waveguide's structured interface with the cover plate enables precise control of light paths through optical design rather than mechanical modification, reducing light scattering while simplifying manufacturing
Solution Approach 2:
The patent changes the optical parameters at the waveguide-cover plate interface by designing specific refraction and reflection characteristics. This allows control over light scattering behavior through optical parameter optimization rather than physical geometry modification, maintaining precision while reducing manufacturing complexity
3Reliability
If photodiodes are placed close to the finger by cutting an opening, then light ray scattering is minimized, but the risk of cover plate rupture increases
Solution Approach 1:
The optical waveguide device acts as an intermediary that transmits light from the finger to photodiodes without requiring the cover plate to be compromised. The waveguide maintains mechanical strength while enabling reliable light transmission through optical coupling, separating the structural and optical functions
Solution Approach 2:
The patent segments the optical transmission function from the structural cover plate by introducing a separate waveguide component. This segmentation allows the cover plate to maintain its integrity and strength while the waveguide handles the light transmission task, ensuring both reliability and structural soundness
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 configuration allows for accurate fingerprint recognition with reduced light scattering, enabling the photosensitive unit to be placed directly under the cover plate without cutting an opening, thus simplifying the manufacturing process and enhancing the accuracy of fingerprint recognition.
Implementation Method 1
an optical waveguide device and a collimator; wherein the collimator is capable of screening collimating light rays in the light rays incident from the target side, and controlling the collimating light rays to be incident to the optical waveguide device... and the optical waveguide device is capable of controlling the collimating light rays incident from the collimator to be incident to the photoelectric converter
Implementation Method 2
a light-emitting structure, a photoelectric converter, an optical waveguide device and a collimator... the photoelectric converter and the collimator are disposed on the same side of the optical waveguide device side by side... the light-emitting structure is capable of emitting light rays to a target side thereof away from the photoelectric converter
Data Source
AI summary
A photosensitive unit, a photosensitive module and a display device are provided. The photosensitive unit includes: a light-emitting structure, a photoelectric converter, an optical waveguide device and a collimator. The converter and collimator are disposed on the same side of the optical waveguide device side by side, the light-emitting structure is disposed on one side of the converter away from the optical waveguide device, and one side on the converter close to the light-emitting structure is light-shielding; the light-emitting structure is capable of emitting light rays to a target side thereof away from the converter; the collimator is capable of screening collimating light rays in the light rays incident from the target side, and controlling the collimating light rays to be incident to the optical waveguide device; the optical waveguide device is capable of controlling the collimating light rays incident from the collimator to be incident to the converter.