Concave Reflector Projection Lens for Short-Throw Distortion Control
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Solution Overview
Problem
Projectors with short focal lengths suffer from image distortion and narrow field of view, compromising image quality, and existing solutions do not adequately address these issues while ensuring efficient projection and cost-effectiveness.
Innovation Solution
A projection optical system with a concave reflector and a lens group comprising a front and rear group lens, utilizing aspheric lenses and specific optical path configurations to enhance image quality and reduce manufacturing costs, while optimizing focal lengths and throw ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focal length is reduced to achieve shorter projection distance, then the projection efficiency is improved, but the image distortion increases and image quality deteriorates
Solution Approach 1:
The projection lens is divided into multiple lens groups (first lens group, second lens group, third lens group) with different functions. The first lens group handles initial imaging, the second lens group (containing the reflector) handles beam expansion and path folding, and the third lens group handles final projection. This segmentation allows each group to be optimized for its specific function, enabling short focal length without excessive distortion.
Solution Approach 2:
A reflector is introduced to fold the optical path, changing the linear arrangement into a multi-dimensional optical path. The optical path is folded back through the lens groups, effectively increasing the optical path length within a compact physical space. This allows the system to achieve short throw ratio while maintaining adequate image quality through proper optical design.
2Area of moving object
If the focal length is reduced to achieve shorter projection distance, then the field of view is improved, but the image distortion increases
Solution Approach 1:
Different regions of the optical system are designed with different properties. The lens groups use different glass materials with varying refractive indices and Abbe numbers, and the reflector is positioned to handle specific angular ranges of light. This local optimization allows the system to maintain low distortion across the entire field of view while achieving a compact form factor.
Solution Approach 2:
The lens groups are constructed using composite optical materials with different refractive indices and dispersion properties. By combining materials with complementary characteristics, the system corrects chromatic aberration and geometric distortion while maintaining a short focal length and wide field of view.
3Manufacturing precision
If a complex optical path configuration is used to improve image quality, then the image distortion is reduced, but the device complexity increases
Solution Approach 1:
Multiple optical functions are merged into a compact arrangement. The reflector serves both to fold the optical path and to expand the beam. The lens groups are arranged in a telecentric configuration that simultaneously achieves multiple optimization goals (distortion correction, field uniformity, and compact size). This merging reduces the number of separate components needed while maintaining image quality.
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 improved image quality, reduced manufacturing costs, and optimized projection ratios, addressing distortion and field of view limitations in projectors with short focal lengths.
Implementation Method 1
a reflector positioned at said lateral side of the lens group; the lens group and the reflector form multiple optical paths between the image source and image
Data Source
AI summary
A projection optical system with a concave reflector in the projection lens, comprising: an image source; a lens group; a reflector; an image and an aperture, the lens group and the reflector form multiple optical paths between the image and image source, each optical path has a chief ray and a marginal ray, the chief ray of one of the optical paths forms a chief ray of a paraxial image height at the part where image source be near to the optical axis, the chief ray of another one of the optical paths forms a marginal ray of an off-axis image height at the part where image source be far from the optical axis; wherein 2.2<F1/F2<3.0; 8<IMH/TR/Fno<19; 5<IMH*T1/T2<8. whereby the optimal optical performance of resolving power and optical path interference allowance will be achieved.