Three-Element Image Pickup Lens Compact Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current image pickup lenses for mobile devices face challenges in downsizing while maintaining high performance and adequate aberration correction, with existing three-element lenses having insufficient back focus and aberration correction.
Innovation Solution
A three-element image pickup lens design featuring a meniscus-shaped positive first lens, an aperture stop, and a negative third lens with a concave surface facing the object side, optimized by specific conditional expressions to reduce total length and correct various aberrations, using plastic materials for cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a meniscus-shaped negative third lens whose convex surface faces the image side is used, then the lens structure is simplified, but the peripheral part of the third lens swells toward the image side causing the back focus to be large and aberration correction to be insufficient
Solution Approach 1:
The patent inverts the conventional meniscus-shaped negative third lens design by using a plano-convex negative lens instead. This inversion changes the curvature configuration from meniscus (where one surface is convex and the other concave) to plano-convex (where one surface is flat and the other is convex), thereby eliminating the peripheral swelling issue while maintaining the negative refractive power needed for the telephoto structure.
Solution Approach 2:
The patent changes the geometric parameters of the third lens by specifying a flat surface on the image side and a convex surface on the object side, with the convex surface having a curvature radius R3 that satisfies the condition -f/(n3-1) < R3 < 0. This parameter modification transforms the lens shape from meniscus to plano-convex, resolving the back focus issue while maintaining optical performance.
2Device complexity
If the third lens is arranged not to touch the substrate to avoid mechanical interference, then the lens assembly is simplified, but the back focus becomes large reducing the compactness of the image pickup apparatus
Solution Approach 1:
The patent modifies the third lens parameters to create a plano-convex shape with specific curvature radius R3 satisfying -f/(n3-1) < R3 < 0. This parameter change reduces the lens thickness and allows the lens to be positioned closer to the image pickup element, thereby reducing the overall back focus distance and enabling more compact apparatus design.
3Reliability
If a three-element lens structure is used to improve performance over one or two-element lenses, then aberration correction is improved, but the total length becomes larger counteracting the downsizing trend
Solution Approach 1:
The patent segments the lens system into three distinct elements with specific functions: a positive meniscus first lens for aberration correction, a negative plano-convex second lens for telephoto effect and compactness, and a negative plano-convex third lens for additional aberration control. This segmentation allows each lens to be optimized for its specific function while maintaining overall compactness.
Solution Approach 2:
The patent employs specific parameter conditions for each lens element: the first lens has curvature radii R1 and R2 satisfying 0 < R1 < R2, the second lens has curvature radius R3 satisfying -f/(n3-1) < R3 < 0, and the third lens has curvature radii R4 and R5 satisfying R4 < R5. These parameter optimizations enable the three-element structure to achieve both aberration correction and compactness.
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 a shorter total length, improved aberration correction, and high image quality, enabling smaller and more efficient mobile image pickup systems.
Implementation Method 1
a first lens having a positive refractive power in a meniscus shape
Implementation Method 2
a second lens having a positive refractive power in a meniscus shape
Implementation Method 3
a third lens having a negative refractive power whose concave surface faces to an object side
Data Source
AI summary
An image pickup lens for forming image of a subject on a solid-state image pickup element includes: a first lens having a positive refractive power in a meniscus shape whose convex surface faces to an object side of the image pickup lens; an aperture stop; a second lens having a positive refractive power in a meniscus shape whose convex surface faces to an image side of the image pickup lens; a third lens having a negative refractive power whose concave surface faces to an object side of the image pickup lens. The first lens, the aperture stop, the second lens and the third lens are arranged in this order form an object side of the image pickup lens. The first lens and the third lens satisfy a predefined conditional expression.