Under-screen Optical Lens for Fingerprint Recognition
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Solution Overview
Problem
Optical lenses used in under-screen fingerprint recognition systems suffer from poor imaging quality and large distortion, leading to low fingerprint recognition rates and high production costs, making them unsuitable for full-screen mobile phones.
Innovation Solution
An optical lens design comprising a flat glass, a first lens with negative refractive power, a stop, a second lens with positive refractive power, and a third lens with positive refractive power, all made of materials with a refractive index of less than or equal to 1.70, arranged to satisfy specific focal length and refractive power ratios, which improves imaging quality and reduces distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high refractive index materials are used for optical lenses in under-screen fingerprint recognition, then the imaging quality and distortion control improve, but the production cost increases significantly
Solution Approach 1:
The patent changes the material parameter from high refractive index to low refractive index (≤1.70), and compensates by optimizing the optical structure parameters including lens curvature radii, thicknesses, and spacing to achieve the required imaging quality without high-cost materials
Solution Approach 2:
The patent uses a composite optical system comprising multiple lenses with different refractive powers (positive and negative) and an infrared filter, where each component is made of low refractive index material but works together as a composite system to achieve high imaging quality
2Device complexity
If conventional optical lens designs are used in under-screen fingerprint recognition, then the structure is simple, but the imaging quality is poor and distortion is large
Solution Approach 1:
The patent divides the optical system into multiple discrete lens elements (first lens with negative refractive power, second lens with positive refractive power, third lens with positive refractive power) and an infrared filter, where each segment contributes to correcting specific aberrations and achieving high imaging quality
Solution Approach 2:
The patent employs aspheric surfaces on the lenses with specific curvature radii (R11, R12, R21, R22, R31, R32) to correct optical aberrations and reduce distortion, moving from simple spherical to optimized aspheric geometries
3Adaptability or versatility
If the optical lens size is reduced for full-screen mobile phones, then the adaptability to full-screen design improves, but the imaging quality and distortion control deteriorate
Solution Approach 1:
The patent compactly nests multiple optical components (flat glass, three lenses, stop, infrared filter) in a small total optical length, with each component optimized to fit within the constrained space while maintaining imaging performance
Solution Approach 2:
The patent optimizes the optical path in multiple dimensions by carefully controlling the spacing between lenses (d1, d2, d3) and using aspheric surfaces to achieve high imaging quality in a compact form factor suitable for under-screen placement
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 optical lens achieves high-quality imaging with small size and low distortion, significantly enhancing fingerprint recognition rates and reducing production costs, making it more suitable for full-screen mobile phone designs.
Implementation Method 1
The first lens has a negative refractive power, the second lens has a positive refractive power, and the third lens has a positive refractive power
Data Source
AI summary
The disclosure provides an optical lens, an imaging device, a fingerprint recognition module and a mobile terminal, along an optical axis from an object side to an image side, the optical lens sequentially including: a flat glass, a first lens, a stop, a second lens, a third lens, and an infrared filter. The optical lens satisfy a high-quality resolution, also have the advantages of small size, small distortion, and high relative illumination, they can effectively improve the rate of the fingerprint recognition, and more suitable for the design requirements of the full screen of the mobile phones. Meanwhile, the three lenses of the optical lens of the present disclosure all use low refractive index materials, which greatly reduces the production cost, and is more in line with the low-cost and high-performance development trend of the full screen of the mobile phone.