Optical Engine for 3D Printing Using Pixel Shifting
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Solution Overview
Problem
Current three-dimensional printing technologies, such as stereolithographic apparatus (SLA), face limitations in achieving finer resolution due to the spatial light modulator's optical resolution, which restricts the detail and accuracy of printed devices.
Innovation Solution
The implementation of a spatial light modulator that outputs modulated light onto overlapping pixel regions, with a pixel shifter moving the modulated light between positions to ensure combined illumination above the curing threshold, allowing for higher resolution by selectively curing only the overlap area, thereby achieving finer details in printed objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spatial light modulator is used to produce patterns with millions of pixels, then layer resolution is improved, but the optical resolution of the spatial light modulator limits the resolution of the printed device
Solution Approach 1:
The patent divides each pixel into multiple sub-pixels (e.g., 2x2, 3x3, or 4x4 grids) to create finer resolution elements. This segmentation allows the system to achieve resolution beyond the native pixel density of the spatial light modulator by treating each pixel as a composite of smaller addressable units, effectively multiplying the resolution capability.
Solution Approach 2:
The patent introduces temporal dimension by sequentially activating different sub-pixel combinations across multiple frames to create intermediate resolution levels. By varying which sub-pixels are active in each frame and using persistence of vision in the photopolymerization process, the system achieves resolution levels between the native pixel grid points, adding a time-based dimension to the spatial resolution problem.
2Reliability
If light intensity is increased to ensure curing above threshold, then curing reliability is improved, but areas outside the intended pattern may also be cured reducing precision
Solution Approach 1:
The patent applies different intensity levels to different sub-pixel regions within the same pixel. By selectively activating specific sub-pixels or combining them in different patterns, the system creates localized variations in light intensity that precisely control where curing occurs. This allows high intensity to be concentrated exactly where needed while keeping surrounding areas below the curing threshold.
Solution Approach 2:
The patent uses partial activation of pixel sub-regions to achieve precise control. Instead of fully activating or deactivating entire pixels, the system partially activates specific sub-pixel portions, applying just enough light energy to cure only the desired areas while leaving adjacent areas sub-threshold. This partial action approach prevents over-curing while maintaining reliability in the intended pattern areas.
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 enhances the resolution of three-dimensional printing by ensuring that only the overlap area receives sufficient illumination, resulting in smaller, more precise features and improved accuracy in the printed objects, overcoming the limitations of traditional pixel-based curing thresholds.
Implementation Method 1
A spatial light modulator outputs modulated light including: modulated first light when the spatial light modulator receives first light; and modulated second light when the spatial light modulator receives second light
Implementation Method 2
The light causes the liquid in the vat to polymerize in that pattern and thus form solid material
Data Source
AI summary
A spatial light modulator outputs modulated light including: modulated first light when the spatial light modulator receives first light; and modulated second light when the spatial light modulator receives second light. Projection optics project the modulated light onto: a first pixel region when a component or the spatial light modulator has a first position; and a second pixel region when the component or the spatial light modulator has a second position. The first and second pixel regions partially overlap. A pixel shifter moves the component or the spatial light modulator between: the first position when the spatial light modulator outputs the modulated first light; and the second position when the spatial light modulator outputs the modulated second light.