Wide Angle Lens Front Group Material Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wide angle lenses for cameras, especially in mobile and surveillance applications, face challenges in reducing size and cost while maintaining optical performance, as excessive simplification of lens systems leads to deteriorated molding and assembly characteristics, increasing production costs.
Innovation Solution
A wide angle lens configuration comprising a front group with three identical plastic lenses and a rear group with at least one positive and one negative lens, where the refractive index and Abbe number of the material satisfy specific conditional expressions, allowing for reduced lens count and cost while maintaining excellent optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of lenses is reduced to decrease device complexity and cost, then the refractive power of each lens becomes too strong and molding characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by carefully selecting the refractive index range (1.48 ≤ NF < 1.6) and Abbe number range (50 ≤ νF < 65) of the plastic material used in the front group lenses. This material parameter optimization allows the lenses to achieve the required optical power without excessive curvature, thereby maintaining good molding characteristics while reducing the total number of lenses.
Solution Approach 2:
The patent employs composite material strategy by using identical plastic material for all three lenses in the front group, while the rear group uses different materials (glass or plastic with different properties). This material uniformity in the front group simplifies manufacturing and reduces costs, while the overall composite structure maintains the necessary optical performance.
2Reliability
If two kinds of plastic material are used to achieve achromatic conditions, then at least two pairs of main molds are required and molding cost increases
Solution Approach 1:
The patent applies homogeneity principle by using the same plastic material for all three lenses in the front group. This uniform material selection eliminates the need for multiple mold pairs, significantly reducing molding costs and manufacturing complexity while still achieving the required achromatic performance through the specific refractive index and Abbe number ranges.
3Device complexity
If the lens system is simplified excessively, then yield rates during molding and assembly drop and production cost increases
Solution Approach 1:
The patent optimizes material parameters (refractive index and Abbe number ranges) to ensure that even with a simplified lens configuration, the lenses maintain appropriate curvature and optical power. This prevents excessive molding difficulty and assembly challenges, thereby maintaining high yield rates while keeping the lens system simple.
4Volume of moving object
If plastic lenses with strong refractive power are used, then the lens size can be reduced, but molding characteristics deteriorate
Solution Approach 1:
The patent carefully controls the refractive index parameter (1.48 ≤ NF < 1.6) to achieve an optimal balance. This parameter selection enables the plastic lenses to provide sufficient optical power for compact lens size while avoiding excessive curvature that would deteriorate molding characteristics. The specific refractive index range ensures that lenses can be made small without becoming too difficult to manufacture.
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 enables a compact, cost-effective wide angle lens with improved optical performance, reduced production costs, and effective aberration correction, suitable for small-sized imaging apparatus.
Implementation Method 1
a lens closest to an image side in the rear group is a negative lens... when a refractive index for d-line of the material of the lenses constituting the front group is NF: 1.48≦NF<1.6
Data Source
AI summary
A wide angle lens consists essentially of a front group and a rear group in this order from an object side. The front group consists essentially of two negative lenses and a positive lens in this order from the object side, and all of the three lenses are made of an identical material. The rear group includes at least one positive lens and at least one negative lens, and a lens closest to an image side in the rear group is a negative lens. When a refractive index for d-line of the material of the lenses in the front group is NF, conditional expression (1): 1.48<NF<1.6 is satisfied.