Five-Lens Imaging System with Aspherical Surfaces for Compact Design
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Solution Overview
Problem
Conventional imaging lenses for portable electronic devices are too long and do not achieve optimal optical performance, making them unsuitable for thin designs in mobile phones and digital cameras.
Innovation Solution
A five-lens imaging lens configuration with specific refractive power and surface designs, including convex and concave portions on each lens element, and a unique sag value distribution on the fourth lens element, which allows for a shorter overall length while maintaining good optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional five-lens imaging lens configurations are used, then optical performance can be maintained, but the system length becomes too long (10-18 mm) for thin portable electronic devices
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive indices, curvature radii, and thicknesses of the five lens elements. Specifically, it uses a negative-positive-positive-negative-positive refractive power configuration with carefully selected parameters (e.g., first lens element with negative refractive power and specific curvature radii R1 and R2) to achieve compact design. The fourth lens element's object-side surface satisfies specific sag ratio relationships (|Sag_r1-Sag_r0|>|Sag_r2-Sag_r1| and |Sag_r3-Sag_r2|>|Sag_r2-Sag_r1|) to control aberrations in the shortened system.
Solution Approach 2:
The patent utilizes aspherical surfaces on multiple lens elements to reduce system length while maintaining optical performance. The first, second, fourth, and fifth lens elements have aspherical object-side or image-side surfaces defined by specific aspherical coefficients (e.g., A04, A06, A08 values). This allows better control of light rays and reduction of spherical aberration, enabling a more compact lens configuration with system length below 4.4 mm.
2Length of moving object
If system length is reduced to meet thin design requirements, then portability is improved, but optical performance (spherical aberration, chromatic aberration) deteriorates
Solution Approach 1:
The patent applies local quality by giving different functional characteristics to different regions of the lens elements. The aspherical surfaces have varying curvature radii at different radial distances from the optical axis, allowing optimized light control for both central and peripheral rays. The fourth lens element's object-side surface has specific sag depth variations at different radial positions (1/3, 2/3, and 1.0 times effective optical radius) to locally correct aberrations in the compact design.
Solution Approach 2:
The patent uses composite material strategies by combining lens elements with different refractive indices and dispersion characteristics. The five lens elements have specifically selected refractive indices (e.g., first lens element with negative refractive power, third lens element made of plastic material with positive refractive power) and Abbe numbers to achieve chromatic aberration correction in the shortened system while maintaining overall compactness.
3Adaptability or versatility
If field of view is enlarged, then imaging capability is improved, but system length increases making it unsuitable for portable devices
Solution Approach 1:
The patent applies dynamics by using aspherical surfaces that dynamically adapt the curvature of light paths. The aspherical coefficients (e.g., A04, A06, A08 terms in the aspherical surface equations) allow the lens to effectively handle a wider angular range of incoming light rays, enabling enlarged field of view (e.g., 49.2 degrees half-field of view in embodiments) without proportionally increasing system length, as the aspherical surfaces optimize ray control for off-axis angles.
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 configuration reduces the system length to below 4.4 mm while achieving low spherical aberration and chromatic aberration, meeting the requirements for imaging quality and enabling the integration of the lens into thin portable electronic devices.
Implementation Method 1
a first lens element having a negative refractive power
Implementation Method 2
a second lens element having a positive refractive power
Implementation Method 3
a third lens element having a positive refractive power... The third lens element is made of a plastic material
Data Source
AI summary
An imaging lens includes first to fifth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant lens parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.