Local Dimming With Dual Modulators for Alignment and Halo Control
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Solution Overview
Problem
Existing dual and multi-modulator projector display systems face challenges in achieving precise time-division alignment and pixel-to-pixel correspondence, leading to difficulties in enhancing contrast ratio and image rendering performance.
Innovation Solution
Employing a dual-modulation scheme with a pre-modulator and a primary modulator, where the pre-modulator spatially modulates a light source to create a blurred light field, which is then pulse-width modulated by the primary modulator, allowing for frame-aligned operation and improved image rendering through light field modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dual and multi-modulator projector display systems are used to improve contrast ratio and light efficiency, then dynamic range is enhanced, but precise time-division alignment and pixel-to-pixel correspondence become difficult to achieve
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing lookup tables (LUTs) that contain compensation data for time-division alignment and pixel correspondence errors before the actual display operation. This allows the system to correct alignment issues without requiring real-time precision, thereby resolving the contradiction between achieving high contrast ratio and maintaining alignment precision.
Solution Approach 2:
The patent implements feedback mechanisms by using measured or modeled error data from the optical system to continuously adjust and compensate for misalignment between modulators. The system measures actual performance deviations and uses this information to refine the LUTs, ensuring precise pixel-to-pixel correspondence and time-division alignment while maintaining enhanced contrast ratio.
2Illumination intensity
If additional modulators are added to improve dynamic range, then light efficiency is enhanced, but system complexity increases
Solution Approach 1:
The patent uses copying by creating virtual models or representations of the optical system's behavior through light field modeling. Instead of physically testing and adjusting each additional modulator configuration, the system creates computational models that predict system performance, thereby reducing the practical complexity of managing multiple modulators while still achieving enhanced dynamic range.
Solution Approach 2:
The patent applies parameter changes by systematically varying key system parameters such as modulator timing, pixel mapping, and optical path characteristics to optimize performance. By changing these parameters in controlled ways and using LUTs to store optimal configurations, the system manages the complexity of additional modulators while maximizing dynamic range and light efficiency.
3Manufacturing precision
If light field modeling is used to improve image rendering, then visual artifacts are reduced, but computational requirements increase
Solution Approach 1:
The patent applies preliminary action by performing computationally intensive light field modeling and error analysis during the calibration phase, storing the results in LUTs for rapid retrieval during normal operation. This shifts the computational burden to an offline setup phase, allowing high-quality image rendering with minimal real-time computational requirements.
Solution Approach 2:
The patent uses partial action by implementing light field modeling at the necessary level of detail without over-engineering the system. The modeling is applied selectively to the most critical aspects of image rendering that impact visual artifacts, achieving sufficient quality improvement without excessive computational overhead.
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 contrast ratio of up to 15,000,000:1 and enhances image rendering performance by minimizing visual artifacts such as bright-clipping, dark-clipping, and halos, while optimizing computational efficiency.
Implementation Method 1
the pre-modulator spatially modulates a light source to create a blurred light field
Implementation Method 2
which is then pulse-width modulated by the primary modulator
Data Source
Figure 1
Figure 2~3A
Figure 3B~3D
AI summary
Dual and multi-modulator projector display systems and techniques are disclosed. In one embodiment, a projector display system comprises a light source; a controller, a first modulator, receiving light from the light source and rendering a halftone image of said the input image; a blurring optical system that blurs said halftone image with a Point Spread Function (PSF); and a second modulator receiving the blurred halftone image and rendering a pulse width modulated image which may be projected to form the desired screen image. Systems and techniques for forming a binary halftone image from input image, correcting for misalignment between the first and second modulators and calibrating the projector system - e.g. over time - for continuous image improvement are also disclosed.