Three-Element Imaging Lens for Compact Wide-Angle Design
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Solution Overview
Problem
Conventional imaging lenses for portable devices struggle to achieve both a small size and a wide angle while effectively correcting aberrations, leading to limitations in image-forming performance and increased fabrication and assembly complexities.
Innovation Solution
A three-lens configuration with all positive refractive powers, where the first and third lenses have positive curvature radii, and the second lens has a focal length that satisfies specific conditional expressions to balance refractive power ratios and focal lengths, ensuring optimal correction of chromatic aberration, field curvature, and astigmatism while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the second lens has negative refractive power to achieve downsizing and correct chromatic aberration, then the imaging lens size is reduced and chromatic aberration is corrected, but the angle of view is limited and fabrication/assembly accuracy requirements increase
Solution Approach 1:
The patent changes the refractive power parameter of the second lens from negative to positive, and adjusts the refractive power ratios and focal lengths of all three lenses according to specific conditional expressions. This parameter change enables the lens to achieve both compact size and wide angle of view while maintaining aberration correction performance.
Solution Approach 2:
The patent uses a composite lens configuration where all three lenses have positive refractive power, combining specific lens materials and shapes (including aspheric surfaces on the first and third lenses) to achieve the desired optical performance. The conditional expressions govern the composite design to balance size, angle of view, and aberration correction.
2Ease of manufacture
If refractive powers of all three lenses are positive to reduce fabrication and assembly accuracy requirements, then manufacturing complexity is reduced, but achieving both small size and wide angle becomes more difficult
Solution Approach 1:
The patent optimizes the refractive power ratios (P1+P3)/P2 and focal length ratios (f3/f1) and (f1/f2) to specific ranges, changing the parameters of all three positive lenses to achieve the right balance. This allows the system to maintain ease of manufacture while achieving compact size and wide angle of view.
3Adaptability or versatility
If aspheric surfaces with inflexion points are used on the second and third lenses to achieve wide angle and aberration correction, then the angle of view is widened and aberrations are corrected, but the lens configuration becomes more complex
Solution Approach 1:
The patent applies aspheric surfaces with inflexion points specifically to the first and third lenses (not the second lens), creating local optical quality enhancements where needed. This selective application corrects aberrations and widens the angle of view while avoiding unnecessary complexity in the entire lens configuration.
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 wider angle and smaller size while maintaining satisfactory image-forming performance, reducing fabrication and assembly complexities, and preventing issues like shading and distortion, thus enhancing the functionality of portable cameras.
Implementation Method 1
a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having positive refractive power, arranged in the order from an object side to an image plane side
Data Source
AI summary
An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having positive refractive power, arranged in the order from an object side to an image plane side. The first lens and the third lens have object-side surfaces and image plane-side surfaces, curvature radii of which are both positive. When the first lens has refractive power P1, the second lens has refractive power P2, the third lens has refractive power P3, the first lens has a focal length f1, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions: 5.0<(P1+P3)/P2<8.5 6<f3/f1<30.