Imaging Lens with Aspheric Elements for Compact Wide-Angle Design
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Solution Overview
Problem
Conventional imaging lenses for mobile devices face challenges in achieving a wide field of view, large aperture value, high resolution, and short total track length simultaneously, often resulting in issues like distortion, long lens length, or compromised image quality in low-light conditions.
Innovation Solution
The design incorporates a specific optical assembly with five lens elements, including a first lens element with positive refractive power, a second and third lens element made of plastic with aspheric surfaces, a fourth lens element with negative refractive power, and a fifth lens element with positive refractive power and multiple inflection points, optimized by specific curvature and focal length conditions to achieve a balanced refractive power distribution and reduced sensitivity to assembly tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If five to six lens elements are used to provide wider angle of view, then the angle of view is improved, but the total track length becomes long and distortion increases
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive powers and curvature radii of each lens element. Specifically, the first lens element has positive refractive power with curvature radius ratio 0.5<R1/R2<2.0, the second has negative refractive power with 0.3<R3/R4<1.5, and subsequent elements have defined curvature ratios. These parameter optimizations enable achieving wide angle of view (80-100 degrees) while maintaining short total track length (TTL<2.0mm)
Solution Approach 2:
The patent employs aspheric surfaces on multiple lens elements to control light rays more effectively. The first, second, third, and fifth lens elements have aspheric object-side or image-side surfaces with defined conic constants and higher-order aspheric coefficients. This curvature optimization allows compact lens design with wide field of view while reducing distortion and maintaining short track length
2Adaptability or versatility
If aperture stop is located behind a second lens element to achieve wide angle of view, then the angle of view is improved, but the track length becomes too long or dark corners are formed
Solution Approach 1:
The patent introduces an aperture stop positioned between the object and the first lens element (specifically, between the object-side surface of the first lens element and the object). This intermediary element controls the light cone angle and aperture effectively, enabling wide angle of view (80-100 degrees) while maintaining short track length (TTL<2.0mm) and preventing dark corner formation by properly managing light distribution across the image plane
3Measurement precision
If refractive power is increased to improve resolution, then image quality is improved, but sensitivity to assembly tolerance increases
Solution Approach 1:
The patent segments the total refractive power across five lens elements rather than concentrating it in one or two elements. The first element has positive power, the second has negative power, the third has positive power, the fourth has negative power, and the fifth has positive power. This segmentation distributes the optical burden, achieving high resolution (0.03mm or better) while reducing sensitivity to assembly tolerances through balanced power distribution
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 enables a wide field of view, large aperture value, high resolution, and a significantly shorter total track length, enhancing image quality and reducing assembly sensitivity while maintaining a compact form factor suitable for mobile devices.
Implementation Method 1
a first lens element with a positive refractive power having an aspheric object-side surface being convex near the optical axis and an aspheric image-side surface being concave near the optical axis
Implementation Method 2
an aperture stop and an optical assembly, the optical assembly comprises, in order from the object side to the image side
Data Source
AI summary
An imaging lens includes an aperture stop and an optical assembly which includes: in order from an object side to an image side: a first lens element with a positive refractive power having a convex aspheric object-side surface and a concave aspheric image-side surface; a plastic second lens element with a positive refractive power having an aspheric object-side surface and a concave aspheric image-side surface; a plastic third lens element with a positive refractive power having aspheric object-side and image-side surfaces; a fourth lens element with a negative refractive power having a concave object-side surface and a convex image-side surface; a plastic fifth lens element with a positive refractive power having a convex aspheric object-side surface, a concave aspheric image-side surface and more than one inflection point. The imaging lens satisfies the following conditions: 0.3<(R5+R6)/(R5−R6)<1.15 and 1.2<TL/ImgH<1.65.