Six-Lens Imaging Assembly Optimizing Chief Ray Angle and Back Focal Length

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Solution Overview

Problem

Conventional imaging lens assemblies face challenges in achieving a compact size while maintaining a suitable chief ray angle, which is essential for portable electronic devices, as they often compromise on image quality due to limitations in chief ray angle and back focal length.

Innovation Solution

The proposed imaging lens assembly consists of six lens elements with specific refractive powers and aspheric surfaces, including a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with positive refractive power, a fourth lens element with positive refractive power, a fifth lens element with negative refractive power, and a sixth lens element with negative refractive power, featuring air gaps between adjacent elements to optimize the chief ray angle and reduce back focal length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the chief ray angle is increased to shorten back focal length and maintain compactness, then the back focal length is reduced and compactness is maintained, but the imaging lens assembly size becomes much greater than the image surface size

Engineering Contradiction:

Improveback focal lengthVSAvoidimaging lens assembly size

Core Design Contradiction:

Length of stationary objectVSVolume of moving object

Solution Approach 1:

The imaging lens assembly is divided into six separate lens elements with air gaps between them, allowing independent optimization of each element's refractive power and surface curvature to achieve the desired chief ray angle while maintaining compact overall size

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different lens elements have different refractive powers (positive or negative) and aspheric surface curvatures tailored to their specific positions in the optical path, enabling precise control of light rays to achieve the target chief ray angle of 38-65 degrees while keeping the assembly compact

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If the imaging lens assembly is made compact to satisfy portable device requirements, then the size is reduced, but the chief ray angle becomes small and image quality deteriorates

Engineering Contradiction:

Improveimaging lens assembly sizeVSAvoidimage quality

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

Multiple aspheric surfaces are employed on the lens elements to precisely control light ray paths and correct optical aberrations, enabling high image quality to be achieved in a compact assembly with adequate chief ray angle

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent optimizes multiple parameters including refractive powers of individual lens elements, air gap distances between elements, and aspheric surface coefficients to achieve the balance between compact size and image quality

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If conventional lens designs are used to achieve compact size, then the assembly is compact, but the chief ray angle is insufficient and back focal length cannot be effectively shortened

Engineering Contradiction:

Improveimaging lens assembly sizeVSAvoidback focal length

Core Design Contradiction:

Volume of moving objectVSLength of stationary object

Solution Approach 1:

Instead of using conventional lens arrangements that prioritize compactness at the expense of chief ray angle, the patent inverts the approach by designing six lens elements with specific refractive powers and air gaps to first achieve the target chief ray angle, then optimizing for compact dimensions

Inventive Principle:

Principle #13The other way round (Inversion)

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

This configuration allows for a compact imaging lens assembly with improved image quality and a larger chief ray angle, effectively maintaining the compact size and enhancing the image quality of portable electronic devices.

Implementation Method 1

an imaging lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The fifth lens element has an object-side surface and an image-side surface being both aspheric. The sixth lens element with negative refractive power has an object-side surface being concave in a paraxial region thereof, wherein the object-side surface and an image-side surface of the sixth lens element are aspheric

Methodology Applied

Scientific EffectOptical aberration correction:

Data Source

PatentUS10007093B2Imaging lens assembly, image capturing apparatus and electronic device

Publication Date: 2018.06.26 LARGAN PRECISION

AI summary

An imaging lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The third lens element has positive refractive power. The fifth lens element has both an object-side surface and an image-side surface being aspheric. The sixth lens element with negative refractive power has an object-side surface being concave in a paraxial region thereof, wherein an object-side surface and the image-side surface of the sixth lens element are aspheric.