Nine-Lens Imaging Lens with Aspherical Ninth Element
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Solution Overview
Problem
Conventional imaging lenses with a nine-lens configuration are too large for small-sized cameras, such as smartphones, and struggle to achieve both downsizing and satisfactory aberration correction.
Innovation Solution
A nine-lens imaging lens configuration with specific refractive power arrangements, including a 'positive-negative-negative-negative' sequence for the first four lenses and a negative refractive power for the ninth lens, along with aspheric surfaces, to optimize focal lengths and curvature radii, allowing for downsizing while maintaining aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a nine-lens configuration is used to correct aberrations, then aberration correction is improved, but the total track length becomes too long for small-sized cameras
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive powers of individual lenses and their spacing relationships. Specifically, it sets the refractive power of the first lens within -0.5<f1/f<0.5, the second lens within -5.0<f2/f1<0.5, and the third lens within 0.5<f3/f1<5.0, where f1, f2, and f3 are the focal lengths of the first, second, and third lenses respectively, and f is the focal length of the entire lens system. These parameter constraints enable aberration correction while maintaining a compact total track length suitable for small-sized cameras.
2Length of moving object
If the first lens is made stronger to downsize the imaging lens, then downsizing is improved, but chromatic aberration correction becomes more difficult
Solution Approach 1:
The patent applies segmentation by dividing the chromatic aberration correction function across multiple lenses rather than relying on a single strong first lens. The lens system includes a first lens with positive refractive power, followed by a second lens with negative refractive power and a third lens with positive refractive power, where each lens contributes to correcting different aspects of chromatic aberration. This segmentation allows the first lens to be made stronger for downsizing while the subsequent lenses compensate for chromatic aberration.
Solution Approach 2:
The patent uses the second and third lenses as intermediary elements between the first lens and the rest of the optical system. The second lens with negative refractive power acts as a mediator to counteract the chromatic aberration introduced by the strong first lens, while the third lens with positive refractive power further refines the correction. This intermediary approach enables the first lens to be optimized for size reduction without sacrificing chromatic aberration correction.
3Manufacturing precision
If three lenses with negative refractive power are arranged on the image plane side of the second lens, then chromatic aberration correction is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the second, third, and fourth lenses to serve multiple functions simultaneously. These lenses not only correct chromatic aberration but also contribute to spherical aberration correction, coma correction, and overall image quality improvement. The fourth lens with negative refractive power is positioned to work in conjunction with the second and third lenses, creating a multi-functional optical group that addresses multiple aberration types without requiring separate correction mechanisms, thereby reducing 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 configuration achieves a compact size suitable for small cameras while effectively correcting chromatic, spherical, and field aberrations, ensuring high image quality and a wider angle of view.
Implementation Method 1
an image plane-side surface of the ninth lens L9 is formed as an aspheric shape having an inflection point... satisfactorily correct paraxial aberrations and aberrations at the periphery thereof, while restraining an incident angle of a light beam emitted from the imaging lens to the image plane
Data Source
AI summary
An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens having negative refractive power; a fourth lens having negative refractive power; a fifth lens; a sixth lens; a seventh lens; an eighth lens; and a ninth lens having negative refractive power, arranged in this order from an object side to an image plane side. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point.