Projection Zoom Lens Aberration Correction via Five-Group Segmentation
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Solution Overview
Problem
Conventional projection zoom lenses suffer from aberrations and limitations in image quality due to the lack of specific relationships between lens groups, particularly the third and other lens groups, which affect the quality of projected images.
Innovation Solution
A projection zoom lens comprising five lens groups with specific refractive powers and movements, where the second, third, and fourth lens groups move towards the screen side while the first and fifth lens groups remain stationary, satisfying certain refractive power conditions to eliminate aberrations and improve image quality, with all lens elements made of glass for heat resistance and ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional projection zoom lens with four lens groups is used, then the device complexity is reduced, but the image quality deteriorates due to uncorrected aberrations from the third lens group
Solution Approach 1:
The projection zoom lens is divided into five distinct lens groups (G1 to G5) with specific refractive powers, where each group serves a particular function in correcting aberrations. The third lens group (G3) with positive refractive power is specifically added to correct aberrations that cannot be corrected by conventional four-group designs, thereby improving image quality without excessive complexity increase.
Solution Approach 2:
Each lens group is assigned specific local optical properties: G1 (negative) for wide-angle correction, G2 (positive) for focal length adjustment, G3 (positive) for aberration correction, G4 (negative) for telephoto correction, and G5 (positive) for final focus. This localized optimization of each group's refractive power enables precise control over overall image quality while maintaining manageable system complexity.
2Manufacturing precision
If the third lens group movement is not controlled, then the device complexity is reduced, but the aberration correction capability deteriorates
Solution Approach 1:
The lens groups G2, G3, and G4 are designed to move dynamically along the optical axis during zooming operations, with their positions interdependently controlled to maintain optimal aberration correction across all focal lengths. The third lens group (G3) moves in coordination with G2 and G4, creating a dynamic system that adapts to different zoom positions while continuously correcting aberrations.
Solution Approach 2:
The patent establishes specific mathematical relationships between the positions and refractive powers of multiple lens groups, creating a feedback mechanism where the movement of one group influences the required positions of others. This interdependent control ensures that aberration correction is maintained throughout the zoom range, with the third lens group's position being critically linked to the overall correction system.
3Ease of manufacture
If glass lens elements are used, then the heat resistance and manufacturing ease are improved, but the device complexity increases due to additional lens groups
Solution Approach 1:
All lens elements within each lens group are made from glass materials with consistent optical properties, ensuring homogeneous manufacturing processes and quality control. This uniform material selection across all five lens groups simplifies production while the five-group configuration provides the necessary complexity for superior aberration correction and thermal stability.
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 solution effectively corrects aberrations and enhances image quality by satisfying specific refractive power conditions, providing stable optical performance resistant to temperature variations and easy manufacturing, suitable for high-end digital lens systems.
Implementation Method 1
a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power
Data Source
AI summary
A projection zoom lens includes, from a screen side to an image source side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power. Zooming the projection zoom lens from the wide-angle end to the telephoto end causes the second, third and fourth lens groups to move toward the screen side, and the first and fifth lens groups are kept stationary. The projection zoom lens may further include an auto iris being axially movable with the fourth lens group, a composite prism and a cover glass. The projection zoom lens satisfies several conditions so that it can effectively eliminate aberrations and improve the projection image quality.