Four-Lens Middle Stop Optical System for Compact Imaging
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Solution Overview
Problem
Compact image capturing devices, such as cameras and mobile phones, face challenges in achieving high image quality due to misalignment issues in lens units, which increase manufacturing costs and product defects, and existing four-lens structures either suffer from insufficient aberration correction or increased length.
Innovation Solution
A four-lens middle stop type lens unit is designed with a first lens having positive power, a second lens also with positive power, an aperture stop, a third lens with negative power, and a fourth lens, arranged from the object side to the image side, forming a composite lens structure that reduces thickness and suppresses aberrations while preventing misalignment-related defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a four-lens structure is used to suppress aberrations, then image quality is improved, but the length of the lens unit increases
Solution Approach 1:
The patent applies nesting by placing the aperture stop inside the lens structure, specifically between the second and third lenses from the object side. This middle stop configuration allows the stop to be integrated within the lens assembly rather than adding external length, enabling aberration correction while maintaining compact dimensions suitable for mobile phone cameras
Solution Approach 2:
The patent optimizes specific parameter ranges including the focal lengths of individual lenses, the position of the aperture stop, and the spacing between lens elements. By carefully controlling these parameters, the design achieves effective aberration suppression in a compact four-lens configuration that fits within mobile phone camera constraints
2Length of moving object
If a front stop lens system is used, then the structure is compact, but misalignment greatly affects image quality and increases manufacturing defects
Solution Approach 1:
The patent uses the aperture stop as an intermediary element positioned in the middle of the lens system rather than at the front. This middle stop configuration acts as a mediator that reduces the impact of misalignment on image quality, as light rays passing through the stop are less sensitive to lateral displacement of lens elements compared to front stop designs
3Power
If the positive refractive power of the second lens is increased to cope with insufficient light condensing, then the condensing ability is improved, but the thickness of the second lens and the entire lens unit increases
Solution Approach 1:
The patent combines the light condensing function with the aperture stop by positioning the stop between the second and third lenses. This merging of functions allows the system to achieve sufficient light condensing without requiring excessive positive power in the second lens, thereby avoiding increased lens thickness and overall unit length
Solution Approach 2:
The patent optimizes the refractive power of the second lens within a specific range and compensates for light condensing requirements through the combined effect of the lens group and aperture stop configuration. This parameter optimization achieves adequate light condensing while maintaining compact lens dimensions suitable for mobile phone cameras
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 effectively reduces the size of the lens unit, minimizes product defects caused by misalignment, and maintains high optical performance, making it suitable for compact imaging devices.
Implementation Method 1
a first lens (1) having positive power, a second lens (2) having positive power, an aperture stop (5), a third lens (3) having negative power, and a fourth lens (4) These lenses refract light to form images on the image sensor while correcting various optical aberrations
Data Source
AI summary
A lens unit includes a first lens having positive power, a second lens having positive power, an aperture stop, a third lens having negative power, and a fourth lens. The first lens, the second lens, the aperture stop, the third lens, and the fourth lens are arranged in order from an object side toward an image side.