Five-Element Aspheric Lens System for Astigmatism Correction
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Solution Overview
Problem
Conventional compact imaging lens systems with four or five lens elements fail to provide high image quality due to limited astigmatism correction and low relative illumination, especially in portable electronic devices, where the second and third lens elements lack sufficient curvature, leading to vignetting and undesirable image quality.
Innovation Solution
An image capturing lens system comprising five lens elements with specific refractive powers and surface curvatures, including a first lens with positive refractive power, a second with negative refractive power, a third with positive refractive power, a fourth with negative refractive power, and a fifth with refractive power, where the curvature radii of the second and third lens elements are optimized to improve astigmatism correction and relative illumination, and the surfaces are aspheric to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lens system uses conventional four or five lens elements, then the device complexity is reduced, but the astigmatism correction capability is insufficient and image quality deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the curvature radii of the second and third lens elements according to specific formulas, and by designing aspheric surfaces with precise mathematical parameters. These parameter optimizations enable effective astigmatism correction while maintaining a compact five-element structure, resolving the contradiction between correction capability and device complexity.
2Illumination intensity
If the second and third lens elements have insufficient curvature, then the manufacturing is simpler, but the relative illumination is low and vignetting occurs
Solution Approach 1:
The patent changes the curvature parameters of the second and third lens elements by defining specific relationships between their curvature radii (R3, R4, R5, R6) through mathematical formulas. This parameter optimization ensures sufficient curvature to prevent vignetting and improve relative illumination while keeping the manufacturing precision within achievable limits.
Solution Approach 2:
The patent applies spheroidality by designing the second and third lens elements with optimized curved surfaces rather than flat or weakly curved surfaces. The specific curvature relationships ensure that light rays from off-axis positions can pass through the lens system with appropriate angles, reducing vignetting and improving relative illumination distribution across the image plane.
3Manufacturing precision
If the lens elements use spherical surfaces, then the manufacturing is easier, but the off-axis aberrations increase and image quality decreases
Solution Approach 1:
The patent transitions from spherical to aspheric surfaces by defining mathematical equations for the lens element surfaces. The aspheric designs include higher-order terms that enable precise correction of off-axis aberrations such as astigmatism and field curvature, significantly improving image quality while the standardized aspheric profiles keep manufacturing feasible through modern molding or grinding techniques.
4Length of moving object
If the lens system is designed for compact size, then the portability is improved, but the astigmatism correction capability is limited
Solution Approach 1:
The patent achieves compact size with effective astigmatism correction by optimizing the curvature radii parameters of the second and third lens elements according to specific formulas. The parameter relationships are designed to maximize correction effectiveness within the constrained physical dimensions, enabling high image quality in a compact form factor suitable for portable electronic devices.
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 proposed lens system significantly improves resolution and image quality by effectively correcting astigmatism and increasing relative illumination, while reducing off-axis aberrations and sensitivity, making it suitable for high-performance portable electronic devices.
Implementation Method 1
a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with positive refractive power, a fourth lens element with negative refractive power
Data Source
AI summary
This disclosure provides an image capturing lens system comprising: a positive first lens element having a convex object-side surface; a negative second lens element having a concave object-side surface; a positive third lens element having a convex object-side surface; a negative fourth lens element having a concave object-side surface and a convex image-side surface; a fifth lens element with refractive power having a concave image-side surface, the shape of the image-side surface changing from concave at the paraxial region thereof to convex while away from the paraxial region thereof, both of the object-side and image-side surfaces being aspheric.