Long-Focus Lens Assembly With Small-Stroke Macro Focusing
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Solution Overview
Problem
Current camera modules with long-focus lenses require large focusing strokes, leading to weak focusing capability and poor imaging quality due to system aberrations, and are challenging to miniaturize.
Innovation Solution
A long-focus lens design comprising fixed first and third lens assemblies and a movable second lens assembly, with appropriate focal powers and safe distances, allows for focusing with a small stroke, suppressing aberrations and enabling high imaging quality and macro capabilities while facilitating miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large focusing stroke is used to implement focusing in a long-focus lens, then the focusing range is improved, but the system aberration increases and imaging quality deteriorates
Solution Approach 1:
The lens system is divided into three lens assemblies: a first lens assembly with positive focal power, a second lens assembly with negative focal power that moves for focusing, and a third lens assembly with positive focal power. This segmentation allows the moving second lens assembly to correct aberrations while providing focusing capability, resolving the contradiction between focusing range and imaging quality.
2Adaptability or versatility
If a large focusing stroke is required for focusing, then the focusing capability is improved, but the motor volume increases and miniaturization becomes difficult
Solution Approach 1:
The patent changes the optical parameters of the lens system by using a negative focal power for the second lens assembly and specific focal length ratios (0.3<F2/EFL<0.7 and -0.1<F3/EFL<0.3). This parameter optimization enables effective focusing with a reduced focusing stroke, thereby decreasing motor volume and facilitating miniaturization while maintaining focusing capability.
3Volume of moving object
If the focusing stroke is reduced for miniaturization, then the motor volume is improved, but the focusing capability may be compromised
Solution Approach 1:
The second lens assembly is designed with negative focal power and positioned between the first and third lens assemblies with specific spacing relationships (0.05<T1/EFL<0.2 and -0.05<T2/EFL<0.1). This localized optimization of the middle lens assembly's optical properties enables it to provide effective focusing capability with minimal movement, achieving both reduced motor volume and maintained focusing performance.
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 design achieves strong focusing capability, high imaging quality, and miniaturization by reducing the focusing stroke and motor volume, while maintaining uniform image quality across long-shot and close-up modes.
Implementation Method 1
a first lens assembly, a second lens assembly, and a third lens assembly that are arranged from an object side to an image side... the second lens assembly moves toward the object side along an optical axis
Data Source
AI summary
This application discloses a long-focus lens, a camera module, and an electronic device. The long-focus lens includes a first lens assembly, a second lens assembly, and a third lens assembly that are arranged from an object side to an image side. The first lens assembly and the third lens assembly are fixed lens assemblies, and the second lens assembly is a focusing lens assembly. In a focusing process in which the long-focus lens is switched from a long shot to a close-up, the second lens assembly moves toward the object side along an optical axis, a combined focal length of the first lens assembly and the second lens assembly decreases, and a combined focal length of the second lens assembly and the third lens assembly decreases. The foregoing long-focus lens has a strong focusing capability and high imaging quality.