Projection Optical System Folding Mirror Light Path
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Solution Overview
Problem
Conventional projection optical systems face issues where light is blocked, and the optical system needs to be buried behind the surface to be projected on, especially when the projection distance is less than the total length of the optical system, leading to difficulties in installation and shadow projection problems.
Innovation Solution
A projection optical system is designed with a first optical system having positive power and a folding mirror that folds the light path in a plane including the optical axis and the normal of the surface to be projected on, with specific conditional expressions for d1 and d2 to prevent light blocking, allowing the system to project without being buried and reducing shadow issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the projection distance is reduced to avoid shadow projection, then the advantage of ultra short-focus projectors is achieved, but the optical system must be buried behind the projection surface when the projection distance is less than the total length of the optical system
Solution Approach 1:
The patent introduces a folding mirror to fold the optical path in a direction perpendicular to the original optical axis, transforming a linear one-dimensional optical path into a two-dimensional folded path. This allows the optical system to achieve ultra-short projection distance while avoiding the need to be buried behind the projection surface, as the folded optical path extends in a different spatial dimension.
Solution Approach 2:
The optical system is divided into multiple segments: a first optical system, a folding mirror, and a second optical system. This segmentation allows each component to be optimized independently and positioned to avoid mutual obstruction, enabling the overall system to achieve compact projection distance without requiring burial installation.
2Length of moving object
If a folding mirror is disposed between the first optical system and the second optical system to reduce projection distance, then ultra short-focus projection is achieved, but light may be blocked by the first optical system or the second optical system
Solution Approach 1:
The patent applies local quality by making the folding mirror have different reflection characteristics at different positions. Specifically, different regions of the folding mirror reflect light from different object points to different image points, ensuring that light from the entire object field is properly directed without obstruction, thereby maintaining light transmission reliability while achieving compact projection.
Solution Approach 2:
By folding the optical path in a perpendicular direction using the folding mirror, the patent creates additional spatial dimension for light propagation. This dimensional change allows light rays that would otherwise be blocked by optical components to travel along a folded path, ensuring complete light transmission while achieving ultra-short projection distance.
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
This configuration enables the projection optical system to project images without being buried into the surface, reduces projection distance, and alleviates shadow issues, while maintaining performance and allowing for flexible design and aberration correction.
Implementation Method 1
a folding mirror; and a second optical system including at least one reflection surface having power
Data Source
AI summary
A disclosed projection optical system projects images on a surface to be projected on. The projection optical system includes a first optical system including at least one refraction optical system and having positive power as a whole, a folding mirror, and a second optical system including at least one reflection surface having power and having positive power as a whole. Further the folding mirror folds a light path from the first optical system to the second optical system, and in a plane including an optical axis of the first optical system and a normal line of the surface to be projected on, the following conditional expressions (1) through (3) are satisfied (1) 0.43≦d1, (2) 0.43≦d2, and (3) 0.7≦d2/d1≦2.0.