Birefringent Crystal Fingerprint Module Eliminates Moire Patterns
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Solution Overview
Problem
Current fingerprint recognition systems in mobile terminals suffer from reduced accuracy due to the generation of moire patterns between the fingerprint module and the screen, which cannot be completely eliminated by rotating the module, and this affects space utilization in the device.
Innovation Solution
Incorporating a crystal with a birefringent effect as an anisotropic medium between the lens and the optical fingerprint chip, which refracts incident light to reduce spatial frequency and eliminate moire patterns, thereby improving recognition accuracy without the need for module rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fingerprint module is arranged below the screen with a lens and light filter, then the module can capture fingerprint information through reflected light, but a moire pattern is generated between the fingerprint module and the screen, reducing recognition accuracy
Solution Approach 1:
The patent removes the light filter component from the fingerprint module and replaces it with a crystal that has birefringent properties. This extraction of the filtering function and replacement with a crystal-based solution eliminates the moire pattern interference while maintaining the ability to capture fingerprint information through the screen.
Solution Approach 2:
The patent changes the optical parameters of the system by introducing a crystal with specific birefringent properties. This crystal modifies the polarization state of light and reduces the spatial frequency of the optical signal, thereby eliminating the moire pattern and improving fingerprint recognition accuracy without requiring module rotation.
2Measurement precision
If the fingerprint module is rotated to eliminate moire patterns, then recognition accuracy improves, but space utilization in the device is reduced
Solution Approach 1:
The patent replaces the mechanical solution of rotating the fingerprint module with an optical solution using a birefringent crystal. Instead of physically reorienting the module to eliminate moire patterns, the crystal optically processes the light to remove interference, thereby maintaining recognition accuracy without consuming additional installation space.
3Use of energy by moving object
If a light filter is used in the fingerprint module, then light transmission to the optical fingerprint chip is enabled, but the filter contributes to moire pattern generation
Solution Approach 1:
The patent extracts the light filtering function from the traditional light filter component and replaces it with a crystal that performs both transmission and interference elimination. This allows the system to maintain efficient light transmission to the optical fingerprint chip while eliminating the moire pattern that was generated by the conventional light filter.
Solution Approach 2:
The patent uses a crystal with birefringent properties as a composite optical element that combines the functions of light transmission and moire pattern elimination. This composite material approach allows simultaneous achievement of efficient light transmission and interference reduction, replacing the separate light filter component.
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 birefringent crystal effectively reduces spatial frequency and eliminates moire patterns in the fingerprint image, enhancing recognition accuracy and optimizing space utilization in the device by eliminating the need for module rotation.
Implementation Method 1
incident light including fingerprint information is incident to the crystal through the lens and is incident to the optical fingerprint chip after being refracted by the crystal
Implementation Method 2
a crystal, and an optical fingerprint chip, the crystal being an anisotropic medium
Data Source
AI summary
A fingerprint module includes: a lens, a crystal, and an optical fingerprint chip, where the crystal is an anisotropic medium, the lens is located on one side of the crystal, the optical fingerprint chip is located on the other side of the crystal, and the optical fingerprint chip is fixed in a substrate of an electronic device. Incident light including fingerprint information is incident to the crystal through the lens and is incident to the optical fingerprint chip after being refracted by the crystal; and the optical fingerprint chip is used for generating a fingerprint image, and the fingerprint image is used for fingerprint recognition.