Projection Optical System with Variable Incident Angle for Trapezoidal Distortion Correction
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Solution Overview
Problem
Conventional projection optical systems face challenges in increasing screen size while reducing projection distance and correcting trapezoidal distortion, which occurs when the projection distance is varied, as they fail to effectively adjust focus and correct optical aberrations.
Innovation Solution
A projection optical system that includes one or more reflective surfaces with optical power, allowing for focus adjustment by moving optical devices, and satisfies specific conditional formulas to ensure optimal angle of incidence and projection magnification, thereby correcting trapezoidal distortion and maintaining high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the angle of incidence of rays with respect to the screen surface is increased to reduce projection space, then the screen size can be increased and projection distance reduced, but trapezoidal distortion is significantly produced when projection distance is varied
Solution Approach 1:
The patent employs a variable incident angle mechanism where the angle of incidence is dynamically adjusted based on the projection distance. When the projection distance changes, the optical system automatically modifies the angle at which rays strike the screen, allowing the system to maintain both compact projection space and accurate image geometry without fixed trapezoidal distortion.
Solution Approach 2:
The invention changes the parameter of incident angle dynamically according to projection distance. By varying this optical parameter, the system can adapt to different projection scenarios, reducing trapezoidal distortion while maintaining reduced projection space. This parameter adjustment enables the system to satisfy both the compactness requirement and the geometric accuracy requirement.
2Volume of moving object
If the viewing angle of the projection optical system is increased to reduce projection distance, then the screen size can be increased, but focus adjustment becomes difficult when projection distance is varied
Solution Approach 1:
The patent implements a dynamic focus adjustment mechanism that coordinates with the variable incident angle. When the projection distance changes and the incident angle is adjusted, the focus position is automatically recalibrated through the optical system's movable components, enabling smooth focus transition without user intervention and maintaining clear imaging across different distances.
Solution Approach 2:
The optical system incorporates feedback mechanisms where changes in projection distance and incident angle are detected, and the focus position is automatically adjusted in response. This closed-loop control ensures that focus remains accurate even as viewing angle and projection distance vary, making the system easy to operate across multiple distances.
3Volume of moving object
If a reflective surface is introduced to fold the optical path, then the projection space can be reduced, but trapezoidal distortion correction becomes more difficult
Solution Approach 1:
The patent merges the functions of the reflective surface and distortion correction into a unified optical design. The variable incident angle mechanism is integrated with the reflective surface arrangement, allowing the same optical components to simultaneously achieve compact projection space and correct trapezoidal distortion without requiring separate correction systems.
Solution Approach 2:
By dynamically adjusting the incident angle parameter in coordination with the reflective surface geometry, the system can control the path of light rays to compensate for trapezoidal distortion. This parameter-based approach allows the reflective surface design to inherently provide distortion correction capability, reducing overall system complexity.
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 successfully increases screen size, reduces projection distance, and effectively corrects trapezoidal distortion, maintaining high optical performance and achieving satisfactory focus across varying projection distances.
Implementation Method 1
an optical path within a projection optical system is folded by a reflective surface, and the angle of incidence of rays with respect to a screen surface is increased
Data Source
AI summary
A projection optical system satisfies a conditional formula: 0.01<{(tan θf1−tan θf2)−(tan θn1−tan θn2)}·(β2/β1)<0.20 where the direction of a normal to and the direction of a long side of the screen of the screen surface are referred to as a “z-direction” and an “x-direction”, respectively, the x-z plane component of the angle of incidence with respect to the screen surface is referred to as an “incident angle θ” and when, among rays that pass through the center of an aperture and that are incident on the ends of the upper and lower sides of the screen of the screen surface, the incident angle θ of rays whose incident angle θ is larger is referred to as “θf” and the incident angle θ of rays whose incident angle θ is smaller is referred to as “θn”, θn and θf2 respectively represent, when the absolute value of a projection magnification is the highest or lowest during focus adjustment, the incident angle θf, θn1 and θn2 respectively represent, when the absolute value of the projection magnification is the highest or lowest during focus adjustment, the incident angle θn, and β1 and β2 respectively represent the maximum and minimum values of the projection magnification during focus adjustment (except that β1 and β2 respectively represent, if the projection magnification is negative, a value of the projection magnification when the absolute value thereof is the highest or lowest).