Rear Projection Luminance Uniformity Correction
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Solution Overview
Problem
Rear projection display systems, particularly those used in flight simulation, suffer from luminance non-uniformity due to factors like opacity of materials, non-unity gain diffusion, and changes in effective throw distance, leading to suboptimal visual performance.
Innovation Solution
A method and system that calculate luminance uniformity by determining baseline luminance values for each primary color, correcting luminance across the rear projection screen, and allocating correction between optical filters and electronic corrections to achieve uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rear projection systems use curved screens, then the field of view and immersion are improved, but luminance uniformity deteriorates due to opacity variations, non-unity gain diffusion, and change in effective throw distance
Solution Approach 1:
The patent applies local quality by implementing spatially-varying correction factors across different regions of the curved screen. The system calculates and applies position-dependent luminance corrections that account for local variations in opacity, diffusion characteristics, and throw distance, allowing each region to be optimized independently while maintaining overall luminance uniformity
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting luminance correction parameters based on measured screen characteristics. The system modifies effective luminance values through computational adjustments that compensate for physical variations in the curved screen's optical properties, transforming the non-uniform luminance distribution into a uniform one
2Illumination intensity
If luminance correction is applied to achieve uniformity, then luminance uniformity is improved, but the projector's dynamic range may be reduced due to overcorrection
Solution Approach 1:
The patent implements feedback by measuring actual luminance values at multiple screen positions and using these measurements to iteratively refine correction factors. The system continuously monitors luminance uniformity and adjusts correction parameters accordingly, preventing overcorrection that would compress the projector's dynamic range while still achieving the desired luminance uniformity
Solution Approach 2:
The patent applies partial correction by implementing position-dependent correction factors that are calibrated to achieve uniformity without applying excessive correction across the entire screen. The system selectively applies correction only where needed based on measured luminance variations, preserving the projector's dynamic range in regions where uniformity is already acceptable
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 effectively enhances luminance uniformity across rear projection screens, improving visual performance by maintaining dynamic range and contrast, while avoiding overcorrection and preserving the projector's dynamic range.
Implementation Method 1
The optical filter is configured to dim specified areas within the corrected color image according to the allocation
Data Source
AI summary
Generating luminance uniformity in a rear projection display system is provided. The method comprises calculating luminance generated by a projector on a rear projection screen relative to a design eye position in front of the screen. A baseline luminance is determined for each primary color according to the luminance. Luminance of all locations on the screen is corrected toward the baseline. Correction is allocated between an optical filter and electronic correction. Luminance is measured at calibration points on the screen. The electronic correction for a color image is adjusted according to the allocation and the luminance at the calibration points to produce a corrected color image for projection from the projector. The corrected color image is projected from the projector and through the optical filter. The optical filter is configured to dim specified areas within the corrected color image according to the allocation.