Dynamic Aperture Control for Projector Optics Black Level Reduction
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Solution Overview
Problem
Existing projector technologies face challenges in reducing black level without compromising luminance, leading to insufficient contrast ratio and geometrical light losses due to the use of apertures in illumination and projection lenses.
Innovation Solution
The solution involves adapting the effective étendue of the light source and projector to match the average picture level, using a diffuser element to increase the light source étendue and a controllable aperture to block stray light, ensuring no geometrical light losses and maintaining high contrast ratio without reducing bright pixel luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If apertures are used in the illumination system and projection lens to reduce the black level, then the contrast ratio is improved, but the luminance of bright pixels is reduced due to geometrical light losses
Solution Approach 1:
The patent employs dynamic aperture control where the aperture size is adjusted in real-time based on the displayed image content. When dark scenes are displayed, the aperture constricts to reduce black level and improve contrast ratio. When bright scenes are displayed, the aperture opens to maximize luminance output. This dynamic adaptation resolves the contradiction by optimizing both contrast ratio and luminance according to actual viewing conditions.
Solution Approach 2:
The system changes the aperture parameter dynamically based on image brightness analysis. By monitoring the average brightness level of the displayed content and adjusting the aperture opening accordingly, the system maintains high contrast ratio for dark content while preserving full luminance for bright content, thus resolving the trade-off between these two parameters.
2Illumination intensity
If the effective étendue of the light source is increased to maintain luminance, then the black level reduction capability is compromised
Solution Approach 1:
The system dynamically adjusts the effective étendue by controlling aperture size. When aperture is constricted, the effective étendue is reduced to improve black level reduction capability. When aperture is opened, the effective étendue increases to maintain high luminance output. This dynamic control allows the system to optimize for either black level reduction or luminance maintenance depending on the displayed content.
3Measurement precision
If a fixed aperture is used to reduce stray light, then the contrast ratio improves, but light power is lost reducing overall efficiency
Solution Approach 1:
The aperture transitions from a fixed component to a dynamic control element. The aperture size is continuously adjusted based on the brightness characteristics of the displayed image. For dark scenes requiring high contrast, the aperture constricts to block stray light. For bright scenes where luminance is priority, the aperture opens to maximize light throughput. This eliminates the need for a fixed aperture that would constantly sacrifice light power.
Solution Approach 2:
The system maintains continuous optimization of light utilization by dynamically adjusting aperture size according to content requirements. Rather than using a fixed aperture that continuously wastes light, the dynamic aperture ensures that light power is preserved whenever high luminance is needed, while only constricting when contrast improvement is actually required by the displayed content.
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 approach achieves a significant reduction in black level with minimal impact on luminance, resulting in high contrast ratios and zero or minimal light loss for full white luminance, suitable for high dynamic range projectors in applications like digital cinema and virtual reality.
Implementation Method 1
a means for increasing the light source étendue such as a diffuser element
Data Source
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AI summary
Projector methods, devices, software are described for a high decrease of the black level without decrease or a limited decrease of the luminance of the bright pixels for use with high contrast and high dynamic range projectors, e.g. based on RGB lasers or phosphor converted lasers. Such projectors can be used in a digital cinema, in a home theatre, in virtual reality systems, in simulators for training, for example. The projector optical system is adapted to vary, according to an average picture level, an effective étendue of the light source and to keep light power confined within a varying cone angle, whereby at the imaging system the projector étendue is matched to the effective étendue of the light source, the effective light source étendue and the projector étendue being controlled to the average picture level.