Five-Lens Plastic Camera Optical System for Wide-Angle Resolution
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Solution Overview
Problem
Existing optical systems for high-resolution cameras in mobile devices face challenges in miniaturization and cost reduction while maintaining optical performance, particularly in satisfying wide-angle and high-resolution requirements with increased sensitivity to manufacturing tolerance.
Innovation Solution
The optical system consists of five lenses with different longitudinal chromatic aberration characteristics, including a meniscus-shaped first lens, a concave second lens, a convex third lens, a convex fourth lens, and a concave fifth lens, with an aperture stop between the first and second lenses to reduce sensitivity and improve illumination, and all lenses are made of plastic with aspherical surfaces to minimize manufacturing costs and enhance design freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the view angle of the lens is increased to 70 degrees or more, then a wider field of view is achieved, but the incident angle of light rays increases causing performance deterioration and increased sensitivity to manufacturing tolerance
Solution Approach 1:
The optical system is divided into five separate lens sheets with different functions: the first lens provides wide-angle capability, the second lens corrects chromatic aberration, and the third and fourth lenses correct field curvature and distortion. This segmentation allows each lens to be optimized for its specific function, reducing overall sensitivity to manufacturing tolerance while achieving 70 degrees or more view angle
Solution Approach 2:
Each lens sheet is designed with specific local optical properties: the first lens has positive refractive power for wide-angle, the second lens has negative refractive power with specific dispersion characteristics for chromatic aberration correction, and the third and fourth lenses have specific shapes for field curvature correction. This local optimization of optical properties reduces sensitivity to manufacturing tolerance in each component
2Measurement precision
If the pixel size of the sensor is decreased to increase the number of pixels to eight million or more, then higher resolution is achieved, but the required spatial frequency increases making the optical system more sensitive to manufacturing tolerance
Solution Approach 1:
The optical system uses five lens sheets with specialized functions to collectively achieve the required optical performance for 8 million pixels. The second lens specifically addresses chromatic aberration with negative refractive power, while the third and fourth lenses correct field curvature and distortion, thereby reducing sensitivity to manufacturing tolerance at high spatial frequencies
Solution Approach 2:
The optical system employs composite lens design with different glass materials having specific refractive indices and Abbe numbers. The second lens uses material with negative refractive power and specific dispersion characteristics to correct chromatic aberration, enabling high resolution performance with reduced sensitivity to manufacturing variations
3Reliability
If four sheets of lenses are used with crown or flint based glass lenses, then chromatic aberration can be compensated, but it is difficult to satisfy miniaturization and cost reduction requirements
Solution Approach 1:
The patent changes the material parameter from traditional crown or flint glass to plastic material for all five lens sheets. This parameter change enables mass production through injection molding, significantly reducing cost and facilitating miniaturization while maintaining chromatic aberration correction capability through the specific design of the second lens with negative refractive power
Solution Approach 2:
The optical system uses five lens sheets instead of four, with the second lens specifically designed with negative refractive power to compensate for chromatic aberration. This segmentation of functions allows plastic material to be used throughout while maintaining optical performance, achieving both miniaturization and cost reduction
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 achieves a wide view angle and high resolution while reducing sensitivity to manufacturing tolerance, allowing for compact and cost-effective production of optical systems for mobile devices, effectively correcting chromatic aberration and improving ambient light handling.
Implementation Method 1
a first lens having positive refractive power and a meniscus shape concave toward an image
Implementation Method 2
a second lens having negative refractive power and a shape concave toward the image
Implementation Method 3
the first and second lenses include an aperture stop disposed therebetween in order to block unnecessary light in light passing through the optical system
Implementation Method 4
a third lens having the positive refractive power and a shape convex toward an object
Implementation Method 5
a fourth lens having the positive refractive power and a shape convex toward the image
Implementation Method 6
a fifth lens having the negative refractive power, a shape convex toward the object and concave to the image, and one or more inflection point provided on an image surface
Data Source
AI summary
Disclosed herein is an optical system for a camera. The optical system for a camera includes: a first lens having positive refractive power and a meniscus shape concave toward an image; a second lens having negative refractive power and a shape concave toward the image; a third lens having the positive refractive power and a shape convex toward an object; a fourth lens having the positive refractive power and a shape convex toward the image; and a fifth lens having the negative refractive power, a shape convex toward the object and concave to the image, and one or more inflection point provided on an image surface.