Projection Lens Group Configuration for Aberration Correction
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Solution Overview
Problem
Existing projection systems with zooming functions have a high number of lenses, which increases manufacturing costs without ensuring optimal optical performance.
Innovation Solution
A projection system with a configuration of up to 13 lenses or fewer, utilizing specific lens groups and conditional expressions to maintain optical performance, including fixed and moving lens groups, and aspheric surfaces to achieve desired focal lengths and refractive indices, ensuring optimal magnification and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of lenses is reduced, then manufacturing cost is reduced, but optical performance may deteriorate
Solution Approach 1:
The projection lens is divided into seven lens groups (first through seventh lens groups) with specific functions. Each lens group contains one or more lenses with predetermined focal lengths and optical properties. This segmentation allows the system to achieve complex optical functions with fewer total lenses compared to conventional designs, reducing manufacturing cost while maintaining optical performance through optimized group configurations.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens group including focal length ratios (e.g., 0.3 ≤ f2/fw ≤ 1.0, 0.5 ≤ |f5/fw| ≤ 2.0), number of lenses per group, and optical properties. By optimizing these parameters within defined ranges, the system achieves superior optical performance with a reduced lens count, directly addressing the contradiction between manufacturing cost and optical performance.
2Area of stationary object
If the maximum half field angle is increased, then wide-angle performance is improved, but aberration correction becomes more difficult
Solution Approach 1:
The patent combines multiple optical functions into specific lens groups. For example, the fourth lens group contains both positive and negative lenses working together to correct aberrations, and the fifth lens group with its negative focal length contributes to both wide-angle performance and aberration correction. This merging of functions allows the system to achieve a maximum half field angle of 25° or more while maintaining excellent aberration correction.
Solution Approach 2:
The patent employs aspheric surfaces in certain lens groups, particularly in the fifth lens group which has a negative focal length. The aspheric surfaces enable effective correction of off-axis aberrations including distortion and field curvature, allowing the system to achieve wide-angle performance (maximum half field angle ≥ 25°) with excellent image quality across the entire field.
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 reduced manufacturing costs while maintaining or improving optical performance by optimizing lens configuration and movement, ensuring effective magnification and aberration correction within specified field angles.
Implementation Method 1
The projection lens includes a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group sequentially from a magnifying side toward the demagnifying side
Implementation Method 2
The fifth lens group is formed of one negative lens having an aspheric surface facing the magnifying side and an aspheric surface facing the demagnifying side
Data Source
AI summary
A projection system has a zooming function and is configured that light rays from a telecentric system enter. The projection system is formed of seven lens groups. The first and seventh lens groups are fixed when the projection magnification is changed, and the second, third, fourth, fifth, and the sixth lens groups move along the optical axis when the projection magnification is changed. The second lens group is formed of one positive lens. The third lens group is formed of one positive lens. The fourth lens group is formed of one or two positive lenses and one negative lens having the center of curvature located at the magnifying side. The fifth lens group is formed of one negative lens having a magnifying-side aspheric surface and a demagnifying-side aspheric surface with each of the surfaces having the center of curvature located at the demagnifying side.