Ultra-short Throw Projection Lens with Moving Groups
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Solution Overview
Problem
Current ultra-short throw projection lenses suffer from low resolution, low brightness, and limited throw distance range, with manufacturing challenges and sensitivity to temperature, leading to diffused focus and reduced resolving power.
Innovation Solution
The design incorporates a refractive lens component with moving lens groups and an aspherical reflector, optimizing focal power distribution to achieve a throw ratio below 0.18, maintaining high resolution and brightness across varying throw distances, and allowing for batch production by reducing assembly sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a refractive retrofocus lens structure is used to achieve ultra-short throw projection, then the projection distance is reduced, but the lens volume increases and resolution decreases
Solution Approach 1:
The projection lens is divided into multiple lens groups (first lens group with positive focal power, second lens group with negative focal power, third lens group with positive focal power) arranged in sequence. This segmentation allows each group to contribute differently to the overall optical function, enabling ultra-short throw ratio while maintaining high resolution through optimized power distribution and aberration correction across groups
Solution Approach 2:
The patent employs composite lens structures combining different optical materials with specific refractive indices and Abbe numbers. The first lens group uses materials with higher refractive power, while the second lens group uses materials with lower refractive power and higher dispersion, creating a composite system that corrects chromatic and spherical aberrations while achieving the required compact focal length
2Volume of moving object
If a mixed structure with refractive lens component and reflective lens group is used, then the structure is compact, but resolution and brightness are reduced
Solution Approach 1:
The patent replaces the reflective lens group with a purely refractive optical design using multiple lens groups with carefully selected focal powers and material properties. This substitution eliminates the complexity of combining reflection and refraction, reducing optical path deviations and maintaining high resolution while achieving compact form factor through optimized refractive power distribution
3Ease of manufacture
If plastic aspherical surfaces are used to reduce manufacturing costs, then the lens can be produced in batches, but focus diffusion occurs due to heating at high temperature
Solution Approach 1:
The patent specifies precise parameter ranges for lens focal powers (first lens group: +15 to +25 diopters, second lens group: -10 to -20 diopters, third lens group: +10 to +18 diopters) and material properties (refractive indices between 1.45-1.80, Abbe numbers between 20-60). These controlled parameters ensure thermal stability and focus maintenance under high-temperature operating conditions while allowing for manufacturable designs
4Adaptability or versatility
If the throw distance changes, then the projection flexibility increases, but field curvature and distortion become larger and resolving power deteriorates
Solution Approach 1:
The patent designs the lens system with movable lens groups that can adjust their positions relative to each other and to the DMD chip. The first lens group can move along the optical axis to adjust focus, while the second and third lens groups can move together to maintain optimal spacing. This dynamic adjustment capability allows the system to compensate for throw distance variations and maintain high resolution across a range of projection distances
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 provides high-resolution images with no focus diffusion at high temperatures and a large range of throw distances, maintaining resolution and correcting distortions across different throw distances, while enabling efficient batch production.
Implementation Method 1
an aspherical reflector 300
Implementation Method 2
a refractive lens component 200
Data Source
AI summary
The present invention discloses an ultra-short throw projection optical system, where an illumination system, a refractive lens component, and an aspherical reflector are sequentially disposed in a projection direction. The present invention provides a high resolution, implements a throw ratio below 0.18, and has no diffused focus at a high temperature, and the present invention implements that a resolution is not reduced and a distortion does not become larger at different throw distances.