Five-Lens Optical System for Wide Field of View and Compact Design
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Solution Overview
Problem
Conventional imaging lens assemblies with large angles of view suffer from ineffective aberration correction and a bulky design, particularly in compact electronic devices like vehicle cameras and rear-view cameras, which require high-resolution, wide-angle lenses with a moderate total track length and reduced back focal length.
Innovation Solution
The optical image capturing lens system employs a specific arrangement of five lens elements with varying refractive powers and surface curvatures, including a negative refractive power for the first lens, positive for the second, negative for the third, positive for the fourth, and negative for the fifth, along with a tighter lens element arrangement and a smaller back focal length, to achieve a wide field of view while minimizing aberrations and maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional imaging lens assembly uses a four-element design with negative front group and positive rear group to achieve wide field of view, then the field of view is enlarged, but the aberration correction becomes ineffective
Solution Approach 1:
The lens assembly is divided into five distinct lens elements with alternating refractive powers (negative, positive, negative, positive, negative). This segmentation allows each element to contribute differently to the overall optical function, with the negative elements primarily controlling field of view and the positive elements providing aberration correction, thereby resolving the contradiction between wide field of view and effective aberration correction
Solution Approach 2:
Different regions of the lens elements have optimized surface curvatures and refractive powers tailored to their specific functions. The first lens element has a convex object-side surface for wide angle capture, while the second lens element has a concave object-side surface optimized for aberration correction. Each element's local optical properties are independently optimized to achieve both wide field of view and high image quality
2Manufacturing precision
If the lens elements are arranged with larger spacing to reduce aberrations, then the image quality improves, but the total track length increases making the device bulky
Solution Approach 1:
The patent optimizes specific parameter relationships to achieve compact design: the axial distance between adjacent lens elements is controlled within specific ranges (e.g., T23/T12 between 0.5-1.5, T34/T23 between 0.3-1.0), and the central thickness of each element is precisely controlled. These parameter optimizations allow aberration correction without requiring excessive spacing, maintaining compact total track length while achieving high image quality
Solution Approach 2:
The lens assembly uses lens elements with different refractive indices and Abbe numbers (e.g., V2/V3 between 1.5-3.0) to achieve chromatic aberration correction in a compact form. The combination of materials with complementary optical properties allows multiple aberration corrections to occur simultaneously within limited space, improving image quality without increasing total track length
3Length of moving object
If the back focal length is reduced for compact device integration, then the overall size decreases, but the aberration correction capability is compromised
Solution Approach 1:
Instead of placing the aperture stop at the traditional front position, the patent positions it between the first and second lens elements. This inverted positioning allows the stop to work in conjunction with the negative first element and positive second element to control both field of view and aberrations efficiently within a compact back focal length, achieving high image quality in a shortened optical path
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 effectively enlarges the field of view, reduces aberrations, and shortens the total track length, resulting in a more compact and high-quality imaging lens system suitable for portable electronic devices.
Implementation Method 1
an optical image capturing lens system comprises 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 has negative refractive power, and thereby it is favorable for enlarging the field of view of the system. When the second lens element has positive refractive power, and thereby can provide significant refractive power needed for the system
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
This invention provides an optical image capturing lens system comprising: a negative first lens element (110) having a convex object-side surface and a concave image-side surface at the paraxial region; a positive second lens element (120); a negative third lens element (130); a positive fourth lens element (140) having a convex image-side surface at the paraxial region; and a negative plastic fifth lens element (150) having a convex object-side surface at the paraxial region as well as a concave at the paraxial region and convex at the peripheral region image-side surface, at least one of the object-side and image-side surfaces being aspheric. The optical image capturing lens system of the present invention effectively increases the angle of view to a proper range and suppresses the distortion. In addition, the present invention has a tighter arrangement of the lens elements and a smaller back focal length, and therefore is more appropriate for the compact device.