Four-Element Plastic Lens System for Mobile Camera Miniaturization
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Solution Overview
Problem
Conventional optical lens systems for mobile phone cameras, comprising three or four glass spherical lens elements, face challenges in achieving higher resolution and miniaturization due to insufficient degrees of freedom and increased manufacturing complexity, particularly in reducing the system's length and correcting chromatic aberration and distortion.
Innovation Solution
A four-lens optical lens system with a first positive refractive power element, a second negative refractive power element, a third negative refractive power element with aspheric surfaces, and a fourth negative refractive power element, optimized with specific refractive index and curvature relationships, along with an aperture stop placement to enhance telecentricity and correct aberrations, using plastic materials for injection molding to reduce size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional three-lens or four-lens glass spherical lens elements are used, then the optical system can be assembled, but the degree of freedom is insufficient and manufacturing complexity increases
Solution Approach 1:
The patent changes the fundamental parameters of the lens system by using plastic injection-molded lens elements instead of glass spherical elements. This allows for more complex surface profiles (aspheric surfaces, inflection points) and varied refractive indices that can be precisely controlled during injection molding, thereby increasing the degree of freedom in optical design while simplifying manufacturing through a single molding process rather than complex glass bonding operations.
Solution Approach 2:
The patent employs plastic materials with different refractive indices for different lens elements, creating a composite optical system. The first lens element has a first refractive index and the second lens element has a second refractive index, allowing independent optimization of each element's optical properties while maintaining compatibility through the injection molding process, thus resolving the contradiction between design freedom and manufacturing complexity.
2Manufacturing precision
If glass spherical lens elements are bonded together, then chromatic aberration can be corrected, but the manufacturing process becomes more difficult
Solution Approach 1:
The patent extracts the bonding process from the manufacturing sequence by using separate injection-molded plastic lens elements that are assembled rather than bonded. This eliminates the difficult glass bonding process while maintaining aberration correction capabilities through the optical design of the plastic elements, which can be precisely molded with complex surface profiles.
Solution Approach 2:
The patent replaces expensive, difficult-to-manufacture glass spherical lens elements with more economical plastic injection-molded elements. The plastic elements can be mass-produced through injection molding with precise optical surfaces, reducing manufacturing difficulty and cost while achieving the same aberration correction effects.
3Volume of moving object
If the optical system length is reduced for miniaturization, then the device size decreases, but aberration correction becomes more difficult
Solution Approach 1:
The patent utilizes aspheric surfaces and inflection points on the plastic lens elements to achieve effective aberration correction within a compact optical system. The aspheric curvature and inflection points provide additional degrees of freedom for correcting optical aberrations without requiring increased system length, thereby achieving miniaturization while maintaining high optical precision.
Solution Approach 2:
The patent changes the refractive index parameters and surface curvature parameters of the plastic lens elements to optimize aberration correction within a reduced system volume. The injection molding process allows precise control of these parameters, enabling effective aberration correction in a compact design that would be difficult to achieve with conventional glass spherical lenses.
4Measurement precision
If pixel size is reduced to increase resolution, then the sensor detail improves, but the optical system requires higher precision and becomes more difficult to design
Solution Approach 1:
The patent employs plastic lens elements with precisely controlled refractive indices and surface profiles (aspheric, inflection points) to achieve the high precision required for small pixel sizes. The injection molding process enables accurate reproduction of complex optical surfaces with tight tolerances, providing the necessary optical precision for high-resolution imaging without proportionally increasing design complexity.
Solution Approach 2:
The patent uses composite plastic materials with specifically selected refractive indices for different lens elements to optimize the optical system for high-resolution imaging. This allows for tailored optical properties that can be precisely controlled during injection molding, achieving the necessary precision for working with reduced pixel sizes while maintaining manageable design complexity through material selection rather than complex geometries alone.
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 system effectively improves image quality by correcting various aberrations, reducing the total track length, and enhancing the field of view, while maintaining miniaturization and cost-effectiveness through precise correction of chromatic and high-order aberrations.
Implementation Method 1
a first lens element with positive refractive power; a second lens element with negative refractive power
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; a second lens element with negative refractive power; a third lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a fourth lens element with negative refractive power being provided with at least one aspheric surface. In the optical lens system for taking image, the number of lens elements with refractive power is limited to four. Such arrangements can reduce the volume and the sensitivity of the optical lens system while providing higher resolution.