Internal Focusing Lens for Mobile Devices
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Solution Overview
Problem
Existing single focus imaging lenses for mobile devices face challenges in adjusting focus without increasing the overall length, especially when dealing with higher pixel counts, as they often require complex lens barrel constructions and cannot effectively implement internal focusing systems.
Innovation Solution
A single focus imaging lens configuration with a front lens group, a rear lens group, and a focusing lens between them, where the focusing lens moves on the optical axis to adjust focus, with specific refractive power and focal length conditions to maintain compactness and high performance, allowing for internal focusing type adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If focusing by moving the whole lens system is adopted, then focus adjustment is achieved, but the overall length changes and the lens barrel construction becomes complex
Solution Approach 1:
The lens system is divided into three distinct groups: a front lens group with positive refractive power, a rear lens group with negative refractive power, and a focusing lens with positive refractive power positioned between them. This segmentation allows the focusing lens to move independently for focus adjustment while the other lens groups remain stationary, avoiding the complexity of moving the entire lens system.
Solution Approach 2:
The focusing lens is designed to move dynamically along the optical axis for focus adjustment, while the front and rear lens groups remain fixed. This dynamic element enables focus control without changing the overall lens barrel construction, resolving the contradiction between ease of operation and device complexity.
2Manufacturing precision
If the number of lenses is increased to cope with higher pixel counts, then imaging performance improves, but the overall size of the lens system increases
Solution Approach 1:
The patent employs aspheric surfaces on the lenses to change the geometric parameters of the lens surfaces. This allows for better correction of optical aberrations and improved imaging performance without increasing the number of lenses or the overall system size, as the aspheric shapes enable more efficient light control.
Solution Approach 2:
The lens system uses combinations of different glass materials with specific refractive indices and Abbe numbers to achieve optimal imaging performance. By carefully selecting and combining materials, the patent corrects chromatic and spherical aberrations effectively without adding more lens elements, thus maintaining compact dimensions.
3Device complexity
If internal focusing system is adopted, then focus adjustment is achieved without changing overall length, but the image plane changes largely and the lens cannot cope with higher pixel counts
Solution Approach 1:
The focusing lens is designed with specific local optical properties, including a positive refractive power and specific focal length relationships with the other lens groups. This localized optimization of the focusing lens ensures that internal focusing can be achieved while maintaining image plane stability and accommodating higher pixel counts.
Solution Approach 2:
The patent establishes specific parameter relationships, particularly the conditional expression 0.5 < f/FL < 2.0, where f is the focal length of the imaging lens and FL is the focal length of the focusing lens. By controlling these parameters, the invention achieves internal focusing with minimal image plane shift, resolving the contradiction between overall length stability and image plane stability.
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 enables good focus adjustment without changing the overall length, optimizing power balance and aberration correction, facilitating miniaturization and high performance while supporting higher pixel counts.
Implementation Method 1
a focusing lens, disposed between the front lens group and the rear lens group, that has a positive refractive power and moves on an optical axis for adjusting focus
Data Source
AI summary
A single focus imaging lens comprises: a front lens group including one or two lenses and having a positive refractive power as a whole; a rear lens group including two or three lenses and having a negative refractive power as a whole; and a focusing lens, disposed between the front lens group and the rear lens group, that has a positive refractive power and moves on an optical axis for adjusting focus, wherein the following conditional expression is satisfied: <?in-line-formulae description="In-line Formulae" end="lead"?>1.0<FL/f<5.0 (X)<?in-line-formulae description="In-line Formulae" end="tail"?> where f: focal length of the single focus imaging lens; FL: focal length of the focusing lens.