Aspheric Plastic Lens System for Mobile Camera Miniaturization
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Solution Overview
Problem
Conventional high-resolution mobile phone camera optical lens systems face challenges in miniaturization and image quality due to the complexity of spherical lens elements and difficulties in gluing glass lenses, which restricts the degree of freedom and increases the length of the optical system, while also being prone to chromatic aberration and shading issues.
Innovation Solution
A four-lens optical lens system comprising a plastic first lens with positive refractive power, a second lens with negative refractive power, a meniscus third lens with negative refractive power, and a fourth lens with negative refractive power, using aspheric surfaces and injection molding to reduce aberrations and system size, with specific focal length and Abbe number relationships to optimize image quality and correct chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical glass lens elements are used with gluing process, then chromatic aberration can be eliminated, but the degree of freedom of the optical system is reduced and the system length increases
Solution Approach 1:
The patent changes the material parameter from glass to plastic and the surface geometry parameter from spherical to aspheric. This allows the lens elements to be molded as single pieces without gluing, maintaining chromatic aberration correction through material selection while preserving optical system freedom and reducing overall complexity
Solution Approach 2:
The patent divides the optical system into four separate plastic lens elements with aspheric surfaces, each optimized for specific aberration correction. This segmentation allows independent optimization of each element without the constraints of gluing spherical glass elements, achieving better overall system performance
2Reliability
If spherical glass lens elements are used with gluing process, then chromatic aberration can be eliminated, but the gluing process is difficult to control
Solution Approach 1:
The patent extracts and eliminates the gluing process entirely by molding complete lens elements with integrated structures. The aspheric plastic lenses are manufactured as single pieces using injection molding, removing the problematic gluing step while maintaining the ability to correct chromatic aberration through material and geometric design
Solution Approach 2:
The patent replaces the mechanical gluing process with a molding process. Instead of assembling and gluing spherical glass elements, the system uses injection-molded plastic lenses with aspheric surfaces that achieve the same optical correction goals without requiring difficult-to-control adhesive bonding
3Measurement precision
If more lens elements are added to improve resolution, then image quality improves, but the system length increases
Solution Approach 1:
The patent employs aspheric surfaces on all four lens elements instead of spherical surfaces. This allows each element to be more compact while maintaining or improving resolution, as aspheric geometry provides better aberration control per unit length, thereby reducing the overall optical system length for a given resolution target
4Illumination intensity
If the aperture stop is located close to the object side, then the exit pupil is far from the image plane improving photosensitivity, but the incident angle becomes larger causing shading
Solution Approach 1:
The patent uses asymmetric aspheric surface profiles on the lens elements, particularly the fourth lens element, to control the chief ray angles. This asymmetric geometry compensates for the telecentric configuration's tendency toward large incident angles, reducing shading effects while preserving the beneficial photosensitivity characteristics of having the exit pupil far from the image plane
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 improves image resolution, reduces system size, and enhances photosensitivity by maintaining a balance between optical track length and image quality, while using plastic lenses to overcome the limitations of glass lenses in miniaturization and aberration correction.
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 having a concave image-side surface
Data Source
AI summary
An optical lens system for taking image comprises, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power having a concave image-side surface and at least one aspheric surface; a meniscus third lens element with negative refractive power having a convex image-side surface; and a fourth lens element with negative refractive power having a convex object-side surface and an aspheric image-side surface. The above configurations and arrangements of the lens elements can effectively reduce the size of the optical system while improving its resolution.