Four-Element Plastic Lens Assembly for Compact Image Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compact optical image capturing lens assemblies, whether three-element or four-element lens structures, fail to produce high-quality images due to limitations in refractive power distribution, chromatic aberration, and manufacturing complexities, especially with cemented glass lenses which are difficult to attach and manufacture.
Innovation Solution
A compact optical image capturing lens assembly comprising four non-cemented lens elements with specific refractive powers and surface curvatures, made of plastic or glass, arranged to optimize refractive power distribution and reduce total track length, including a first lens with positive refractive power, a second with negative refractive power, a third with positive refractive power and aspheric surfaces, and a fourth with negative refractive power and aspheric surfaces, to correct aberrations and maintain a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a three-element lens structure is used to achieve compact size, then the total track length is reduced, but the image quality deteriorates due to insufficient degrees of freedom in correcting aberrations
Solution Approach 1:
The lens assembly is divided into four separate non-cemented lens elements instead of using a cemented doublet structure. This segmentation provides more independent parameters for aberration correction while maintaining a compact form factor, resolving the contradiction between compact size and image quality.
Solution Approach 2:
The patent introduces aspheric surfaces on the third and fourth lens elements, adding a new dimensional aspect to the lens design. This aspheric configuration provides additional degrees of freedom for correcting spherical aberration and other optical imperfections without increasing the total track length, thus improving image quality within the same compact envelope.
2Manufacturing precision
If glass spherical lens elements are attached to form a doublet lens to eliminate chromatic aberration, then chromatic aberration is corrected, but the manufacturing process becomes difficult and the total optical track length increases
Solution Approach 1:
The patent extracts the chromatic aberration correction function from the cemented glass doublet structure and distributes it across multiple plastic lens elements with different refractive indices. This eliminates the need for difficult glass cementing processes while maintaining effective chromatic aberration correction through the non-cemented multi-element design.
Solution Approach 2:
The patent changes the material parameter from glass to plastic for the lens elements. Plastic materials offer easier manufacturing through injection molding, eliminate the need for cementing operations, and provide sufficient refractive index variation to correct chromatic aberration effectively, thus improving ease of manufacture while maintaining optical performance.
3Manufacturing precision
If multiple spherical lenses are allocated to correct aberrations, then image quality is improved, but the total optical track length increases and the structure becomes more complex
Solution Approach 1:
The patent replaces spherical surfaces with aspheric surfaces on the third and fourth lens elements. This curvature modification enables more efficient aberration correction within a shorter optical path, as aspheric surfaces can correct spherical aberration and other distortions more effectively than spherical surfaces, reducing the need for additional lens elements and track length.
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 improved image quality by correcting aberrations, reducing the total track length, and simplifying the manufacturing process, making it suitable for lightweight and portable electronic products while allowing for easier fabrication and cost reduction.
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
An optical image capturing lens assembly includes four non-cemented lens elements, in order from an object side to an image side: a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The third lens element with positive refractive power has a convex object-side surface and a convex image-side surface, and is made of plastic material, wherein the surfaces of the third lens element are aspheric. The fourth lens element with negative refractive power has a concave object-side surface and a convex image-side surface, and is made of plastic material, wherein the surfaces of the fourth lens element are aspheric.