Three-Piece Plastic Lens Assembly for Wide-Angle Miniaturization
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Solution Overview
Problem
Existing three-piece lens assemblies face challenges in achieving miniaturization while maintaining a wide angle of view and effective aberration compensation, with previous designs either having high magnification or a low angle of view.
Innovation Solution
A three-piece lens assembly comprising a positive meniscus first lens group, a positive meniscus second lens group with a concave surface, and a biconcave third lens group with a stronger curvature on the object side, all made of plastic with aspheric surfaces, which reduces magnification and enhances the angle of view to 70°.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a plastic-made triplet aspheric lens with point of inflexion is used to achieve miniaturization, then the optical length is shortened, but the incident angle design becomes particularly difficult to maintain precision
Solution Approach 1:
The lens assembly is divided into three separate lens groups (first positive meniscus lens, second positive meniscus lens, and third biconcave lens) instead of using a single plastic triplet lens. This segmentation allows each lens to be optimized independently for its specific function while maintaining overall miniaturization, with the third lens group specifically designed to control incident angles at 25 degrees or less
Solution Approach 2:
The patent uses a composite optical system combining different lens materials and designs - plastic aspheric lenses with specific curvature relationships. The third lens group uses a biconcave design with specific radius of curvature ratios (R31/R32 between 0.5-2.0) to compensate for aberrations while controlling incident angles, creating a composite solution that achieves both miniaturization and precision
2Reliability
If the magnification is increased to 1.35-1.48 as in previous designs, then the optical performance is improved, but the angle of view becomes limited to around 62 degrees
Solution Approach 1:
The patent changes key optical parameters including setting the magnification to 1.18-1.20 (lower than previous designs) while adjusting the radius of curvature ratios of the third lens group (R31/R32 between 0.5-2.0) and the focal length ratios (f2/f1 between 0.6-1.2, f3/f1 between -2.0 to -0.5). These parameter changes enable both wide angle of view (70 degrees or more) and good optical performance with effective aberration compensation
3Reliability
If the third lens group uses a biconcave design with specific curvature relationships, then the incident angle is compensated effectively, but the manufacturing complexity increases
Solution Approach 1:
The patent employs aspheric surfaces on all three lens groups with specific curvature relationships. The third lens group uses a biconcave design where the absolute value of the radius of curvature of the object-side surface (R31) is 0.5 to 2.0 times that of the image-side surface (R32). This controlled curvature design effectively compensates for incident angle effects while the aspheric profiles are designed to be manufacturable using standard molding techniques
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 solution achieves a high-performance miniaturized lens assembly with improved aberration compensation and a wider angle of view, suitable for digital cameras and mobile phones, while maintaining cost-effectiveness and manufacturability.
Implementation Method 1
Both sides of the first, second and third lens groups are aspheric
Implementation Method 2
the concave surface of the third lens facing the object side is greater than the another surface of the third lens facing the image side in radius of curvature
Data Source
AI summary
A three-piece lens assembly comprises: a first lens group, a second lens group, a third lens group and an aperture. The first lens group is a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture. The second lens group is a positive meniscus lens with a concave surface facing the aperture and the object side. The third lens group is a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, and the concave surface of the third lens facing the object side is greater than the another surface of the third lens facing the image side in radius of curvature. Both sides of the first, second and third lens groups are aspheric and are all made of plastic material.