Aspheric Imaging Lens Assembly for Compact Mobile Devices
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Solution Overview
Problem
Conventional compact imaging lens assemblies for mobile devices face challenges in achieving high image quality, resolution, and compact size due to the limitations of spherical-surface glass lenses and complex manufacturing processes, failing to meet the demands of advanced smartphone and PDA camera modules.
Innovation Solution
A compact imaging lens assembly comprising five lens elements with specific refractive powers and surface profiles, including aspheric surfaces, an aperture stop placement between the object and second lens element, and an air distance between the first and second lens elements, optimizing the total track length and image quality while maintaining a compact form.
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 and manufacturing becomes complicated
Solution Approach 1:
The patent employs aspheric surfaces instead of spherical surfaces for the lens elements. The aspheric curvature allows for better control of light paths and aberrations while enabling a more compact overall lens structure. Specifically, the first lens element has a convex aspheric surface and the fourth lens element has a concave aspheric surface, which facilitates shorter track length while maintaining optical performance.
Solution Approach 2:
The patent changes the refractive index parameters and curvature parameters of the lens elements to optimize the balance between aberration correction and compact size. By carefully selecting the refractive indices of the lens materials and adjusting the surface curvatures, the design achieves effective chromatic aberration correction within a reduced track length configuration.
2Manufacturing precision
If spherical-surface glass lenses are used, then chromatic aberration is corrected, but manufacturing process becomes complicated
Solution Approach 1:
The patent replaces complex multi-element spherical glass lens assemblies with a design using aspheric surfaces. The aspheric curvature can be manufactured more efficiently than precision spherical surfaces, and the reduced number of lens elements (five elements compared to conventional four-element spherical designs) simplifies the manufacturing process while maintaining aberration correction capabilities.
3Device complexity
If conventional four lens elements system is used, then structure is simple, but image quality and resolution do not satisfy high standard mobile devices
Solution Approach 1:
The patent uses aspheric surfaces on multiple lens elements (first, fourth, and fifth elements) to improve image quality and resolution. The aspheric curvature provides better control over light rays, reducing optical aberrations and enhancing sharpness, thereby achieving high image quality while maintaining a moderate number of lens elements.
Solution Approach 2:
The patent optimizes the refractive indices, curvatures, and spacing parameters of the five lens elements to achieve superior image quality. By carefully adjusting these parameters, the design surpasses the performance of conventional four-element systems while keeping the structure relatively simple.
4Ease of operation
If aperture stop is placed closer to the sensor, then telecentric feature is improved, but field of view becomes narrower
Solution Approach 1:
The patent employs the fifth lens element with a concave aspheric surface and inflection point to dynamically adjust the light cone geometry. This element helps in optimizing the balance between telecentricity and field of view by controlling the bending of light rays in a flexible manner, allowing the aperture stop to be positioned optimally for both requirements.
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 reduces the size and sensitivity of the lens assembly, enhances image resolution, corrects aberrations, and achieves a balance between telecentric feature and wide field of view, enabling installation in compact portable electronic products.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element having a concave object-side surface; a fourth lens element with positive refractive power having a convex image-side surface
Data Source
AI summary
This invention provides an imaging lens assembly including five lens elements with refractive power, in order from an object side toward an image side: a first lens with positive refractive power having a convex object-side surface, a second lens with negative refractive power, a third lens having a concave object-side surface, a fourth lens with positive refractive power having an object-side surface and a convex image-side surface, and at least one of both surfaces thereof being aspheric, a fifth lens with negative refractive power having a concave image-side surface with at least one inflection point formed thereon. An aperture stop is positioned between an imaged object and the second lens. The imaging lens assembly further comprises an electronic sensor on which an object is imaged. With such arrangement, the size and the optical sensitivity of the lens assembly can be reduced. A high image resolution is also obtained.