Five-Lens Imaging Assembly with Ultra-Low F-Number and Chief Ray Control

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Solution Overview

Problem

Existing imaging lens assemblies for portable electronic devices, particularly those with an F-number of 2.0 or above, fail to meet the requirements for high image quality in low-light conditions and during hand trembling due to insufficient aperture and optical performance.

Innovation Solution

A miniaturized imaging lens assembly comprising five lenses with specific refractive powers and curvatures, where the effective focal length and entrance pupil diameter satisfy f/EPD≤1.8, and the incident angle of the chief ray corresponding to the maximal field-of-view is less than 15°, ensuring a large aperture and improved image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the F-number is increased to 2.0 or above for miniaturization, then the lens assembly size is reduced, but the image quality in low-light conditions deteriorates

Engineering Contradiction:

Improvelens assembly sizeVSAvoidimage quality in low-light conditions

Core Design Contradiction:

Volume of moving objectVSIllumination intensity

Solution Approach 1:

The patent changes the F-number parameter from conventional values (2.0 or above) to an ultra-low F-number (F1.8 or below), specifically achieving F1.6 in embodiments. This parameter change allows larger aperture relative to focal length, improving low-light image quality while maintaining miniaturized form factor through optimized optical design

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If the F-number is reduced to improve aperture, then the image quality in low-light conditions is improved, but the lens assembly complexity increases

Engineering Contradiction:

Improveaperture sizeVSAvoidlens assembly complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent divides the optical system into five distinct lens elements with specific refractive power configurations (positive, negative, positive/negative, positive/negative, negative). Each lens element is optimized for specific functions: the first lens for light gathering, the second for aberration correction, and subsequent lenses for fine-tuning optical performance. This segmentation allows achieving ultra-low F-number while controlling complexity through specialized design of each element

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines multiple optical functions into a compact five-lens assembly, integrating aperture control, aberration correction, and focal length management in a unified structure. The close spacing and coordinated design of the five lenses enable them to work together as an integrated optical system, achieving ultra-low F-number without proportionally increasing overall complexity

Inventive Principle:

Principle #5Merging (Combining)

3Illumination intensity

If the aperture is enlarged to improve low-light performance, then the image quality is improved, but the lens assembly thickness increases

Engineering Contradiction:

Improvelow-light performanceVSAvoidlens assembly thickness

Core Design Contradiction:

Illumination intensityVSLength of moving object

Solution Approach 1:

The patent changes the F-number parameter to ultra-low values (F1.8 or below, specifically F1.6), which mathematically requires a larger aperture diameter relative to focal length. This parameter change is achieved through optimized lens curvatures and spacing, allowing large aperture without proportionally increasing the axial thickness of the lens assembly

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent optimizes the radial dimension (aperture diameter) independently from the axial dimension (thickness) by using aspheric surfaces and carefully controlled lens spacing. The five-lens design allows the aperture to be enlarged in the radial direction while maintaining compact thickness in the axial direction through reduced air gaps and optimized refraction angles

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

4Manufacturing precision

If the chief ray incident angle is reduced to improve image quality, then the aberrations are reduced, but the lens design complexity increases

Engineering Contradiction:

Improveimage quality and aberration controlVSAvoidlens design complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies different surface profiles to different lens elements based on their specific functional requirements. The first lens uses an aspheric object-side surface for optimal light gathering, while subsequent lenses use combinations of spherical and aspheric surfaces tailored to their roles in aberration correction. This localized optimization of surface quality allows controlling chief ray angles and aberrations without uniformly increasing design complexity across all elements

Inventive Principle:

Principle #3Local quality

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 provides an ultra-thin large aperture imaging lens assembly with enhanced image quality, effectively addressing the limitations of existing lens assemblies in low-light conditions and reducing aberrations, while maintaining a compact size.

Implementation Method 1

the first lens has a positive refractive power, and an object-side surface of the first lens is a convex surface

Methodology Applied