Five-Element Plastic Lens System Aberration Control
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Solution Overview
Problem
Conventional compact image lens assemblies, whether with four or five lens elements, fail to meet the increasing demands for higher image quality and resolving power in portable electronic devices due to inadequate distribution of negative refractive power and sensitivity issues.
Innovation Solution
A photographing optical lens system comprising five lens elements with specific refractive powers and surface curvatures, including a first lens with positive refractive power, a second with negative power, a third with positive power, a fourth with negative refractive power made of plastic and aspheric surfaces, and a fifth with negative refractive power also made of plastic, where the fifth lens's surface changes from concave to convex, optimizing image quality and reducing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional four lens elements structure is adopted, then the device complexity is reduced, but the image quality and resolving power cannot satisfy high specification requirements
Solution Approach 1:
The patent divides the optical system into five distinct lens elements with specific refractive power distributions. The first lens element has positive refractive power, the second has negative refractive power, the third has positive refractive power, the fourth has negative refractive power, and the fifth has positive refractive power. This segmentation allows each element to contribute specifically to correcting different types of aberrations, thereby achieving high image quality and resolving power while maintaining a compact structure suitable for portable electronic devices.
2Manufacturing precision
If a five lens elements structure is adopted to increase image quality, then the resolving power is improved, but the negative refractive power cannot be properly distributed and sensitivity increases
Solution Approach 1:
The patent assigns specific refractive power characteristics to each lens element position. The first lens element has positive refractive power with a convex object-side surface, the second has negative refractive power, the third has positive refractive power, the fourth has negative refractive power with aspheric surfaces, and the fifth has positive refractive power. This local differentiation of optical properties ensures proper distribution of negative refractive power throughout the system, reducing sensitivity while maintaining high image quality and resolving power.
3Length of stationary object
If the principal point cannot be positioned away from the image plane, then the back focal length is increased, but the compact size requirement is compromised
Solution Approach 1:
The patent employs aspheric surfaces on the fourth lens element (both object-side and image-side surfaces) and the fifth lens element (object-side surface) to control the positioning of the principal point. The aspheric shapes allow for optimized light ray convergence and divergence patterns, enabling the principal point to be positioned away from the image plane. This achieves a reduced back focal length while maintaining the required compact size for portable electronic devices.
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 system achieves improved image quality, reduced sensitivity, and a compact size by properly distributing refractive power and adjusting surface curvatures, enhancing aberration correction and maintaining stable manufacturing processes.
Implementation Method 1
The first lens element with positive refractive power has a convex object-side surface
Implementation Method 2
The second lens element has negative refractive power
Implementation Method 3
The fourth lens element with negative refractive power is made of plastic material, and has a concave object-side surface and a convex image-side surface, wherein at least one of the object-side surface and the image-side surface of the fourth lens element is aspheric
Implementation Method 4
The fifth lens element with negative refractive power is made of plastic material, and has a concave object-side surface and a concave image-side surface, wherein at least one of the object-side surface and the image-side surface of the fifth lens element is aspheric, and the image-side surface of the fifth lens element changes from concave at the paraxial region to convex at the peripheral region
Data Source
AI summary
A photographing optical lens system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has refractive power. The fourth lens element with negative refractive power is made of plastic material, and has a concave object-side surface and a convex image-side surface. The fifth lens element with negative refractive power is made of plastic material, and has a concave object-side surface and a concave image-side surface. At least one surface of the fourth through fifth lens elements is aspheric, and the image-side surface of the fifth lens element changes from concave at the paraxial region to convex at the peripheral region.