Four-Lens Optical Assembly with Aspheric Plastic Elements
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Solution Overview
Problem
Conventional compact image capturing lens assemblies for portable electronic devices suffer from limitations in image quality due to excessive spherical-surface lenses, which restrict the system's degree of freedom, complicate manufacturing, and lead to unwanted light reflections, affecting image quality.
Innovation Solution
An optical image capturing lens assembly comprising four lens elements with specific refractive powers and aspheric surfaces, including a first lens with positive refractive power, a second with negative refractive power, a third with positive refractive power and a concave object-side surface, and a fourth with negative refractive power and at least one inflection point, optimizing the axial distance and curvature radii to reduce the total track length and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spherical-surface glass lenses are used to correct chromatic aberration, then chromatic aberration is corrected, but the total track length cannot be reduced easily and manufacturing becomes complicated
Solution Approach 1:
The patent changes the material parameter from glass to plastic and the surface parameter from spherical to aspheric. This allows the lens to correct both spherical and chromatic aberrations simultaneously while reducing the total track length and simplifying manufacturing through injection molding processes.
Solution Approach 2:
The patent uses plastic material with specific refractive index and Abbe number combinations to achieve chromatic aberration correction without requiring multiple glass lens elements. This composite approach integrates multiple functions into a single element, reducing system complexity.
2Manufacturing precision
If more lens elements are added to improve image quality, then image quality improves, but the total track length increases
Solution Approach 1:
The patent merges multiple functions (spherical aberration correction, chromatic aberration correction, and focusing) into fewer lens elements. The aspheric surfaces and plastic materials enable single elements to perform what previously required multiple separate elements, thereby shortening the total track length.
Solution Approach 2:
The patent employs aspheric surfaces instead of spherical surfaces. This allows for more efficient light ray control and aberration correction within a shorter optical path, reducing the total track length while maintaining or improving image quality.
3Volume of moving object
If lens elements are assembled tightly in compact space, then compactness is achieved, but unwanted light reflections increase affecting image quality
Solution Approach 1:
The patent converts the potential harm of tight spacing by using aspheric surfaces and plastic materials with optimized optical properties. These design choices reduce internal reflections and stray light while maintaining compact dimensions, turning the compactness constraint into an opportunity for optimized optical performance.
4Ease of manufacture
If spherical-surface lenses are used, then manufacturing is simpler, but the degree of freedom is curtailed and aberration correction is insufficient
Solution Approach 1:
The patent changes the surface geometry parameter from spherical to aspheric and the material parameter from glass to plastic. This enables greater design freedom to correct multiple types of aberrations while maintaining manufacturing simplicity through modern injection 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 effectively reduces the total track length, attenuates sensitivity, and improves image quality by correcting spherical and chromatic aberrations, while maintaining a compact form suitable for 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; and a fourth lens element with negative refractive power
Data Source
AI summary
This invention provides an optical image capturing lens assembly comprising four lens elements, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a plastic third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, the object-side and image-side surfaces thereof being aspheric; and a plastic fourth lens element with negative refractive power, an object-side surface and an image-side surface thereof being aspheric, at least one inflection point being formed on at least one of the object-side and image-side surfaces thereof. With the aforementioned arrangement, the total track length of the lens assembly can be effectively reduced, the sensitivity of the system can be attenuated and the image quality can be improved.