Two-Group Variable Magnification Projection Lens with Telecentricity
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Solution Overview
Problem
Conventional variable magnification projection optical systems for projection display devices are bulky, heavy, and costly due to their complex multi-group configurations, and they often fail to maintain telecentricity on the reduction side, which is necessary for applications involving color combining or TIR prisms, limiting their ability to achieve high magnification and compactness.
Innovation Solution
A two-group variable magnification projection optical system with a first lens group having positive refractive power and a second lens group also with positive refractive power, both of which move during magnification changes, ensuring telecentricity on the reduction side, thus reducing size, weight, and cost while maintaining optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-group variable magnification optical system is used to achieve high magnification and telecentricity, then optical performance is improved, but device complexity, size, weight, and cost increase
Solution Approach 1:
The optical system is divided into only two lens groups (first lens group with positive refractive power and second lens group with negative refractive power) instead of the conventional four or more groups, achieving variable magnification through coordinated movement of these two simplified segments while maintaining telecentricity and optical performance
Solution Approach 2:
The patent changes the fundamental parameters of the optical system by using a positive-negative lens group configuration with specific focal length ratios (0.3 < f1/f2 < 1.5) and controlling movement distances to maintain telecentricity, enabling high magnification with reduced complexity
2Adaptability or versatility
If a multi-group variable magnification optical system is used to achieve high magnification, then magnification ratio is improved, but weight increases
Solution Approach 1:
The system uses only two lens groups instead of multiple groups, dramatically reducing the number of optical elements and their associated mounting structures, thereby reducing overall weight while achieving variable magnification through controlled movement of these two lightweight segments
Solution Approach 2:
The patent implements dynamic variable magnification by moving the two lens groups relative to each other along the optical axis, allowing magnification adjustment without adding heavy fixed structures, achieving high magnification ratio with minimal weight increase
3Adaptability or versatility
If a multi-group variable magnification optical system is used to achieve high magnification, then magnification ratio is improved, but device cost increases
Solution Approach 1:
The optical system is simplified to two lens groups with standard optical elements, reducing the number of precision-machined components, alignment requirements, and assembly steps, thereby lowering manufacturing cost while maintaining high magnification capability
Solution Approach 2:
The patent specifies practical parameter ranges (0.3 < f1/f2 < 1.5 for focal length ratio, and specific movement distance relationships) that enable mass production with standard tolerances, making high-magnification telecentric lenses more cost-effective to manufacture
4Device complexity
If a non-telecentric optical system is used to simplify configuration, then device complexity is reduced, but color unevenness and separation efficiency degrade
Solution Approach 1:
The patent achieves telecentricity by controlling the movement distances of the two lens groups relative to each other and to the reference plane, maintaining parallel chief rays without requiring complex additional optical elements, thus preserving color uniformity and separation efficiency while keeping the configuration simple
Solution Approach 2:
The system dynamically maintains telecentricity throughout the variable magnification range by coordinating the movement of the two lens groups, ensuring that the chief rays remain parallel to the optical axis at all magnification settings, thereby maintaining optical performance during dynamic operation
5Reliability
If the first lens group diameter is increased to achieve telecentricity in a two-group system, then telecentricity is improved, but overall length and weight increase
Solution Approach 1:
The patent optimizes the focal length ratio (0.3 < f1/f2 < 1.5) and movement distance relationships between the two lens groups to achieve telecentricity with compact dimensions, avoiding the need for excessive lens group diameters or overall system length by carefully controlling the optical parameters
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 a compact, lightweight, and cost-effective design with improved optical performance by maintaining telecentricity and securing sufficient back focus for prism insertion, while minimizing aberration variations across the magnification range.
Implementation Method 1
a first lens group having a positive refractive power and moved during magnification change, and a second lens group having a negative refractive power and moved during magnification change, disposed in order from the magnification side
Data Source
AI summary
A variable magnification projection optical system substantially consisting of two lens groups of a first lens group having a positive refractive power and is moved during magnification change, and a second lens group having a positive refractive power and is moved during magnification change, in which the variable magnification projection optical system is configured such that the reduction side is telecentric.