Dual Modulation Projector Halftone Tile Synchronization
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Solution Overview
Problem
Dual modulation projectors face challenges in achieving high contrast ratios at low light levels due to limited discrete pre-modulation levels, which results in reduced image quality and halo artifacts, especially with small tile sizes.
Innovation Solution
The use of multiple halftone images per frame synchronized with a modified bit sequence in the primary modulator increases the number of levels provided by a given tile size without increasing the tile or Point Spread Function (PSF) size, allowing for improved contrast and reduced halo artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If small tile sizes are used in the pre-modulator, then the number of discrete pre-modulation levels is limited, but this reduces contrast ratio at low light levels and increases halo artifacts
Solution Approach 1:
The patent applies periodic action by using multiple halftone images per frame that are sequentially displayed and synchronized with the primary modulator. Instead of using a single static halftone image, the system cycles through multiple halftone representations (e.g., 2-4 halftones per frame), allowing the pre-modulator to effectively provide more discrete light levels over time. This temporal multiplexing resolves the contradiction by maintaining small tile sizes while achieving higher effective contrast through periodic variation of the halftone patterns.
Solution Approach 2:
The patent implements dynamics by transitioning from a static single halftone image to dynamic multiple halftone images per frame. The pre-modulator dynamically switches between different halftone patterns synchronized with the primary modulator's bit sequence, enabling the system to adaptively represent multiple discrete light levels. This dynamic approach allows small tiles to achieve higher effective resolution and contrast ratio by varying the halftone configuration over time rather than being constrained by a fixed single-pattern limitation.
2Area of stationary object
If small tile sizes are used in the pre-modulator, then the system complexity is reduced, but halo artifacts increase due to insufficient discrete levels
Solution Approach 1:
The patent uses periodic action to eliminate halo artifacts by cycling through multiple halftone images per frame. Each halftone pattern is displayed for a specific duration synchronized with the primary modulator, and the human visual system integrates these periodic variations. This temporal sampling approach allows small tiles to achieve smooth gradient transitions without the halo artifacts that would result from using insufficient discrete levels in a single static halftone image.
Solution Approach 2:
The patent introduces an intermediary mechanism by using the primary modulator's modified bit sequence as a mediator between the pre-modulator's multiple halftone images and the final projected image. The bit sequence controls the timing and synchronization of halftone switching, effectively mediating the interaction between the pre-modulator and display medium to produce smooth transitions that minimize halo artifacts while maintaining small tile sizes.
3Manufacturing precision
If multiple halftone images per frame are used, then the number of discrete levels is increased, but the device complexity increases
Solution Approach 1:
The patent merges the control of multiple halftone images with the existing primary modulator operation by synchronizing them through a unified bit sequence. Instead of treating the multiple halftone switching as a separate complex control system, the invention integrates this functionality into the primary modulator's existing timing and control architecture. The modified bit sequence simultaneously drives both the pre-modulator halftone switching and the primary modulator display, reducing overall system complexity despite the increased number of discrete levels.
Data Source
AI summary
Smaller halftone tiles are implemented on a first modulator of a dual modulation projection system. This techniques uses multiple halftones per frame in the pre-modulator synchronized with a modified bit sequence in the primary modulator to effectively increase the number of levels provided by a given tile size in the halftone modulator. It addresses the issue of reduced contrast ratio at low light levels for small tile sizes and allows the use of smaller PSFs which reduce halo artifacts in the projected image and may be utilized in 3D projecting and viewing.