Five-Lens Plastic Module for Chromatic Aberration Control
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Solution Overview
Problem
Miniaturized and lightweight mobile communications terminal camera units face challenges in achieving high resolution and bright optical systems due to difficulties with chromatic aberration when using plastic lenses, which are less effective than glass lenses.
Innovation Solution
A lens module configuration with five lenses, including specific refractive powers and shapes, such as convex and concave meniscus lenses, and a stop placement to satisfy certain conditional expressions, optimizing the lens module's design to improve aberration correction and resolution while maintaining lightness and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If plastic lenses are used to reduce weight and manufacturing cost, then weight and cost are reduced, but chromatic aberration correction becomes more difficult
Solution Approach 1:
The patent divides the optical system into five separate lens elements with specific shape configurations (convex, concave, meniscus) and refractive power distributions. This segmentation allows each lens element to contribute differently to aberration correction, enabling effective chromatic aberration control in plastic lenses through optimized individual element designs rather than relying on a single lens material property.
Solution Approach 2:
The patent employs aspherical surface parameters (higher-order terms like A4, A6, A8 coefficients) to modify the surface geometry of plastic lenses. By changing the surface parameter equations from simple spherical to complex aspherical forms, the patent compensates for the inherent chromatic aberration limitations of plastic materials, achieving better optical performance despite using lighter plastic instead of glass.
2Ease of manufacture
If plastic lenses are used instead of glass lenses, then manufacturing cost is reduced, but optical performance (brightness and resolution) deteriorates
Solution Approach 1:
The patent uses plastic material with specific refractive index ranges (1.50-1.70 for positive power lenses, 1.60-1.80 for negative power lenses) and combines it with aspherical surface designs. This composite approach of selecting specific plastic material properties and pairing them with complex surface geometries achieves glass-level optical performance at lower manufacturing costs, as the aspherical plastic lenses compensate for material limitations.
Solution Approach 2:
By implementing higher-order aspherical parameters (A4, A6, A8 terms with specific coefficient ranges) in the lens surface equations, the patent transforms standard plastic lens performance. These parameter changes in surface geometry enable the plastic lenses to achieve better resolution and brightness control, matching or exceeding traditional glass lens performance while maintaining cost advantages.
3Volume of moving object
If a compact lens module is designed to fit miniaturized terminals, then terminal size is reduced, but optical system brightness (F-number) becomes harder to optimize
Solution Approach 1:
The patent arranges five lens elements in a compact nested configuration along the optical axis with minimized spacing. The lens elements are positioned closely together with specific thickness and air gap dimensions, creating a space-efficient nested structure that achieves miniaturization while maintaining the optical path length needed for adequate light transmission and brightness control.
Solution Approach 2:
The patent optimizes the F-number by adjusting specific parameter ranges: focal length (3.0-6.0mm), stop diameter (0.8-2.0mm), and lens element spacing. By changing these dimensional parameters within optimized ranges, the patent achieves a balance between compact size and brightness, producing an F-number between 1.8-2.8 that provides good illumination in a miniaturized form factor.
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 lens module achieves improved aberration correction, high resolution, and low F-number performance, enabling clear image capture under low illumination conditions while being lightweight and cost-effective.
Implementation Method 1
a first lens having positive refractive power, both surfaces thereof being convex; a second lens having negative refractive power and having a meniscus shape concave toward an image; a third lens having positive refractive power and having a shape convex toward the image; a fourth lens having negative refractive power and having a meniscus shape convex toward the image; a fifth lens having negative refractive power and having a meniscus shape concave toward the image
Data Source
AI summary
There is provided a lens module including: a first lens of which both surfaces are convex; a second lens having a meniscus shape concave toward an image; a third lens having a shape convex toward the image; a fourth lens having a meniscus shape convex toward the image; a fifth lens having a meniscus shape concave toward the image; and a stop disposed in front of an object side of the first lens, wherein when SD is a diameter of the stop and f is an overall focal length of the lens module, SD/f<0.45 is satisfied.