Decentered Dome Corrects Short Throw Projection Distortion
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Solution Overview
Problem
Existing projection systems, particularly those with short throw configurations, face challenges in maintaining image quality due to distortions caused by the use of symmetrical Fresnel lenses in off-axis configurations, which become problematic at high incident angles and are susceptible to image distortion from screen flatness issues.
Innovation Solution
An outer dome made of optically active material is decenterized from the exit pupil, positioned between the projection optics and the projection target, providing protection and introducing a second-order distortion to correct image plane distortions, thereby improving image quality by reducing aberration and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If symmetrical Fresnel lenses are used in off-axis projection systems, then the projection system can achieve a compact design, but image distortion increases significantly at high incident angles
Solution Approach 1:
The patent applies asymmetry by using an asymmetric lens design instead of a symmetrical Fresnel lens. The asymmetric lens has different curvature radii on its object-side and image-side surfaces, allowing it to correct image distortion at high incident angles while maintaining a compact form factor suitable for off-axis projection systems.
Solution Approach 2:
The patent changes the optical parameters by specifying different curvature radii for the object-side and image-side surfaces of the lens. By optimizing these parameters (R1, R2, R3, R4) and the lens position (d1, d2), the system achieves reduced image distortion while maintaining compact dimensions.
2Length of moving object
If the projection lens is positioned close to the screen for short throw projection, then large images can be displayed in small spaces, but image quality deteriorates due to increased distortion
Solution Approach 1:
The asymmetric lens design with different curvature radii on opposite surfaces enables the lens to correct distortion effects that become pronounced in short-throw configurations. This allows the projection lens to be positioned very close to the screen while maintaining image quality.
Solution Approach 2:
The patent optimizes the dynamic performance by carefully positioning the lens at specific distances from both the display element and the screen (d1 and d2 parameters). This dynamic optimization allows the system to achieve excellent image quality across the projection field despite the short throw distance.
3Manufacturing precision
If complex optical elements are used to minimize distortion in short-throw projectors, then image quality can be maintained, but device complexity increases
Solution Approach 1:
The patent applies local quality by designing a lens with specific regional characteristics - the object-side surface and image-side surface have different curvature radii tailored to their respective functions. This localized optimization allows a single lens element to perform multiple correction functions, reducing overall system complexity.
Solution Approach 2:
The patent merges multiple optical functions into a single asymmetric lens element. By combining distortion correction, focusing, and field curvature compensation into one optimized lens, the system achieves high image quality without requiring multiple complex optical elements.
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 decenterized outer dome effectively corrects image distortions and aberrations, enhancing the quality of the projected image while protecting the optical system from physical harm, particularly in off-axis projection systems with high incident angles.
Implementation Method 1
introducing a second-order distortion to correct image plane distortions
Implementation Method 2
configured to provide protection to optical elements provided therein
Data Source
AI summary
The present invention relates to an outer dome configured to provide protection and optical correction to a system of projection optics and the output thereof. More particularly, an optical projection system having an optical offset of greater than 100% is comprised within a projector housing having an outer dome comprised of an optically active material mounted onto an opening approximately coinciding with the optical projection system's exit pupil. The outer dome is configured to be decenterized from the exit pupil (e.g., the center of the dome is offset from the exit pupil in one or more of an x, y, and z direction) such that it provides optical correction to a projected image. Therefore, an outer dome is configured to provide protection to optical elements provided therein and improvement of projected image quality (e.g., reduced image distortion, reduced aberration).