Imaging Lens Assembly with Tilted Fifth Lens for Low F-Number
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Solution Overview
Problem
Current camera lens assemblies for portable electronic devices face challenges in achieving high image quality and miniaturization while maintaining a large aperture, especially in low-light conditions and with hand trembling, as existing designs with an F-number of 2.0 or above are insufficient.
Innovation Solution
An imaging lens assembly comprising five lenses with specific refractive powers and surface configurations, including positive and negative refractive powers, convex surfaces, and optimized surface tilt angles, which allows for a total effective focal length and entrance pupil diameter ratio of f/EPD ≤ 1.9, enhancing light admission and reducing edge field-of-view aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the F-number is reduced to increase light admission, then imaging performance in low-light conditions is improved, but the lens assembly size increases and miniaturization becomes difficult
Solution Approach 1:
The lens assembly is divided into five distinct lens elements with alternating positive and negative refractive powers. This segmentation allows each lens to contribute specifically to light gathering or aberration correction, enabling a smaller overall aperture while maintaining high light admission capability through optimized optical paths.
Solution Approach 2:
The patent employs specific parameter optimizations including surface tilt angles (β5 between -20° to 20°), focal length ratios (f/EPD ≤ 1.9), and curvature radius relationships (R1/R2, R5/R6) to achieve enhanced light admission with reduced lens size. These parameter changes enable compact design without sacrificing illumination intensity.
2Manufacturing precision
If multiple lenses are added to improve image quality and reduce aberrations, then imaging performance is enhanced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Each lens element is designed with specific local characteristics: the first and third lenses have convex object-side surfaces for light convergence, the second and fifth lenses have negative refractive powers for aberration correction, and the fourth lens has positive refractive power for focal adjustment. This local quality differentiation optimizes overall image quality while maintaining manageable complexity through functional specialization.
Solution Approach 2:
The lens assembly employs asymmetric design in the surface tilt angles and curvature radii of individual lenses. Specifically, the fifth lens has a controlled surface tilt angle (β5) and the curvature radius ratios (R1/R2 = -0.5 to -2.0, R5/R6 = -0.5 to -2.0) create asymmetric optical paths that effectively reduce edge field-of-view aberrations while balancing the overall system complexity.
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 provides improved image quality, miniaturization, and reduced sensitivity, achieving better flat field curvature and distortion elimination, making it suitable for portable electronic products.
Implementation Method 1
The first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a positive refractive power, and the fifth lens has a negative refractive power
Data Source
AI summary
The present disclosure discloses an imaging lens assembly. The imaging lens assembly includes sequentially, from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The first lens has a positive refractive power, an object-side surface of the first lens is a convex surface, and an image-side surface of the first lens is a convex surface; the second lens has a negative refractive power; the third lens has a positive refractive power, an object-side surface of the third lens is a convex surface, and an image-side surface of the third lens is a convex surface; the fourth lens has a positive refractive power; and the fifth lens has a negative refractive power, and a surface tilt angle β5 of an object-side surface of the fifth lens at a maximum effective radius satisfies: −20°<β5<5°.