Four-Lens Image Pickup Lens for Wide Angle and Miniaturization
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Solution Overview
Problem
Current image pickup lenses for mobile devices face challenges in achieving high optical performance, wide angle, and miniaturization while maintaining sufficient brightness, due to limitations in aberration correction and lens design, particularly with four-lens configurations that fail to optimize refractive power distribution and focal lengths.
Innovation Solution
A four-lens configuration with specific refractive power and curvature radius conditions, including aspherical surfaces, is employed, featuring an aperture stop, a first lens with positive refractive power, a second meniscus-shaped lens with negative power, a third meniscus-shaped lens with positive power, and a fourth lens with negative power, optimized to achieve miniaturization and wide angle capabilities with a focal ratio number (Fno) less than 2.6.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-piece image pickup lens with a meniscus-shaped positive first lens, meniscus-shaped positive second lens, and negative third lens is used to achieve higher performance, then optical performance is improved, but the peripheral part of the third lens swells toward the image side causing the lens surface position to recede greatly and back focus cannot be made small, leaving room for further improvement in downsizing
Solution Approach 1:
The patent divides the lens system into four separate lenses instead of three, with each lens having specific refractive power assignments. The first lens has positive refractive power, the second lens has negative refractive power, the third lens has positive refractive power, and the fourth lens has negative refractive power. This segmentation allows for better distribution of optical functions and reduces the swelling effect at the periphery of individual lenses, enabling smaller back focus distance while maintaining optical performance.
Solution Approach 2:
The patent changes the refractive power distribution parameters by introducing a fourth lens with negative refractive power. The specific refractive power conditions are defined as: 0.70≦f1/f≦1.05 for the first lens, -1.80≦f2/f≦−1.20 for the second lens, -0.70≦f3/f≦0.10 for the third lens, and -0.90≦f4/f≦−0.50 for the fourth lens. These parameter changes optimize the lens configuration to reduce peripheral swelling and enable compact back focus distance.
2Reliability
If a four-lens configuration is used to improve optical performance, then aberration correction is enhanced, but distributions of the refractive power of the first lens and the second lens are not sufficient, which cannot enable sufficient wide angle and miniature
Solution Approach 1:
The patent assigns specific refractive power characteristics to each lens position to optimize both aberration correction and wide angle capability. The first lens has positive refractive power (0.70≦f1/f≦1.05) for aberration correction, the second lens has negative refractive power (-1.80≦f2/f≦−1.20) for wide angle, the third lens has positive refractive power (-0.70≦f3/f≦0.10) for aberration correction, and the fourth lens has negative refractive power (-0.90≦f4/f≦−0.50) for wide angle. This local optimization of refractive power distribution enables both sufficient aberration correction and wide angle capability.
Solution Approach 2:
The patent uses a composite lens system with four different lenses having different refractive power characteristics. The combination of positive and negative refractive power lenses creates a composite optical system that achieves both aberration correction and wide angle capability. The specific refractive power distribution across the four lenses creates a balanced optical system that satisfies both requirements.
3Adaptability or versatility
If a four-lens configuration is used to achieve wide angle, then full visual angle is reached, but distributions of the refractive power of the first lens and the second lens are not sufficient, which cannot enable sufficient miniature and brightness Fno=2.69 is not sufficient
Solution Approach 1:
The patent optimizes the refractive power parameters of all four lenses to achieve both wide angle and miniaturization. The specific conditions are: 0.70≦f1/f≦1.05 for the first lens, -1.80≦f2/f≦−1.20 for the second lens, -0.70≦f3/f≦0.10 for the third lens, and -0.90≦f4/f≦−0.50 for the fourth lens. These parameter changes create a balanced refractive power distribution that enables wide angle capability while maintaining compact lens size and achieving Fno<2.69.
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 corrects aberrations, achieves wide angle, and miniaturizes the lens design while maintaining brightness, as demonstrated by various embodiments showing excellent optical performance with full visual angles up to 79.4° and Fno values below 2.4, enhancing the optical characteristics of camera modules in mobile devices.
Implementation Method 1
a first lens L1 having a positive refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a fourth lens L4 having a negative refractive power
Data Source
AI summary
An image pickup lens includes, in sequence from an object side to an image side, an aperture stop; a first lens having two convex surfaces and having a positive refractive power; a second lens in a meniscus shape whose convex surface faces to the object side having a negative refractive power; a third lens in a meniscus shape with the convex surface facing to the image side having a positive refractive power; a fourth lens in a meniscus shape with the convex surface facing to the object side having a negative refractive power. Predefined conditions are satisfied.