Wide-Angle Lens with High-Index First Lens
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Solution Overview
Problem
The existing wide-angle lens designs face challenges in manufacturing efficiency and yield rate due to the difficulty in molding the second lens with a deep concave curved surface, which increases production time and costs.
Innovation Solution
A wide-angle lens configuration with a first negative meniscus lens, a second biconcave lens, a third biconvex lens, and a fourth negative lens, where the refractive index and focal length relationships are optimized to allow for a shallow concave curved surface on the second lens, enabling easier manufacturing and reducing aberrations, particularly chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the second lens is designed with a deep concave curved surface to ensure negative power, then the optical performance is improved, but the molding process becomes difficult and production efficiency decreases
Solution Approach 1:
The patent changes the curvature parameter of the second lens from a deep concave surface to a shallow concave surface by adjusting the focal length ratio (f2/f0 < -2.500). This parameter change makes the molding process easier while maintaining optical performance through compensated design of other lens parameters.
2Reliability
If the second lens is designed with a deep concave curved surface, then the negative power is ensured, but the molding time increases and yield rate decreases
Solution Approach 1:
The patent modifies the geometric parameters of the second lens, specifically changing the concave surface curvature to a shallower design. This is achieved by controlling the focal length ratio f2/f0 to be less than -2.500, which reduces molding complexity and time while maintaining the required negative power through overall system optimization.
3Volume of moving object
If the refractive index of the first lens is increased to exceed 1.800, then the lens diameter is reduced and downsizing is achieved, but the manufacturing complexity may increase
Solution Approach 1:
The patent specifies using a lens material for the first lens with refractive index n1 > 1.800. This high refractive index material enables lens downsizing by reducing the required diameter while managing manufacturing complexity through optimized design parameters and the use of advanced molding techniques for high-index plastic materials.
4Manufacturing precision
If the focal length ratio f2/f0 is set to be closer to 0 than -3.000, then various aberrations are corrected, but the design constraints increase
Solution Approach 1:
The patent optimizes the focal length ratio of the second lens to the entire system (f2/f0) to be less than -2.500 (closer to 0 than -3.000). This parameter optimization enables effective aberration correction, particularly chromatic aberration, while the design constraints are managed through coordinated optimization of other lens parameters and the overall four-group configuration.
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 improves production efficiency, reduces production costs, and allows for downsizing of the lens while effectively correcting various aberrations, including chromatic aberration, by using plastic lenses and optimizing the refractive indices and focal lengths to simplify the manufacturing process of the second lens.
Implementation Method 1
when a refractive index of the first lens is set as n1, a focal length of the second lens is set as f2, and a focal length of an entire lens system is set as f0, the refractive index n1, the focal length f2, and the focal length f0 satisfy both of the following conditional expressions, 1.800 < n1
Implementation Method 2
since f2/f0 is smaller than −2.500, the lens surface on the image side of the second lens does not have to be a deep concave curved surface. Accordingly, the second lens can have the structure that is easily manufactured
Data Source
AI summary
To provide a wide-angle lens having a four-group, five-lens configuration and capable of increasing an angle while maintaining productivity of a second lens and an object-to-image distance of an entire lens system is reduced. A wide-angle lens has a four-group, five-lens configuration. A second lens, a third lens, a fourth lens, and a fifth lens are plastic lenses, and the fourth lens and the fifth lens constitute a cemented lens. A refractive index n1 of the first lens is 1.839, which satisfies the following conditional expression (1),1.800<n1 Conditional expression (1),As a ratio between a focal length f2 of the second lens and a focal length f0 of an entire lens system, f2/f0 is −2.680, and satisfies the following conditional expression (2),−3.000<f2/f0<−2.500 Conditional expression (2).