Sub-pixel Shift Illumination for 3D Printing Resolution
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Solution Overview
Problem
Current methods for producing three-dimensional objects by layer-wise solidification of photohardening materials struggle to achieve high resolution in the construction plane without increasing the size of the construction area, as they rely on the resolution of the image forming unit and require complex mechanics for precise alignment of partial planes.
Innovation Solution
The process involves using a rastered image forming unit to create a sequence of images shifted in the sub-pixel range, generating separate masks for each shift, allowing for improved resolution along outer and inner contours without increasing the resolution of the image forming unit or requiring precise alignment of partial planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the resolution of the image forming unit is increased to improve construction plane resolution, then the manufacturing precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent divides a single high-resolution illumination task into multiple lower-resolution passes. The DMD device projects the same layer multiple times with different sub-pixel shifts, effectively segmenting the resolution achievement into incremental steps that accumulate to super-resolution without requiring a single high-resolution DMD.
Solution Approach 2:
The patent transitions from a single-dimensional resolution approach (single pass at native DMD resolution) to a multi-dimensional approach by introducing temporal dimension (multiple passes) and spatial dimension (sub-pixel shifts in X and Y directions). This allows resolution improvement without increasing the DMD's native pixel density.
2Manufacturing precision
If the projection field is down-sized to improve resolution, then the manufacturing precision improves, but the construction area decreases
Solution Approach 1:
The patent makes the projection system dynamic by introducing controlled movements. The DMD or projection optics are shifted by sub-pixel amounts between passes, and the construction platform may be moved to position different areas of the construction field under the projection. This dynamic approach allows the full construction area to be illuminated at each pass while achieving higher effective resolution through multiple passes.
3Manufacturing precision
If multiple partial planes are illuminated separately to improve resolution, then the manufacturing precision improves, but the device complexity increases due to precise alignment requirements
Solution Approach 1:
The patent employs self-aligning mechanisms where the system uses its own resources for alignment. Encoders on the DMD and projection optics provide feedback about their positions, allowing the control system to calculate and apply the correct sub-pixel shifts without external alignment equipment. The system serves its own alignment needs through integrated sensing and control.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with optical and computational methods. Instead of using precision mechanical stages and alignment optics to physically align multiple projection fields, the system uses digital masking, software-controlled DMD pixel addressing, and calculated sub-pixel shifts based on encoder feedback to achieve alignment computationally.
4Manufacturing precision
If the pixel size is reduced to improve resolution, then the manufacturing precision improves, but the construction area decreases
Solution Approach 1:
The patent performs preliminary actions by projecting and accumulating multiple passes of illumination data before the final curing occurs. Each pass deposits a portion of the required energy at slightly different sub-pixel positions, and these preliminary projections are accumulated in the photopolymer material. The full resolution is achieved through this preliminary multi-pass energy deposition before the layer is fully cured and hardened.
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 resolution in the construction plane by overlapping images shifted in the sub-pixel range, allowing for finer details without increasing the construction time or mechanical complexity, enabling flexible resolution improvement within the construction plane.
Implementation Method 1
layer-wise solidification of a material solidifiable by the action of electromagnetic irradiation
Data Source
AI summary
The invention relates to a process or a device for the production of a three-dimensional object by layer-wise solidification of a material which is solidifiable under the application of electromagnetic irradiation by means of mask illumination, wherein the mask is produced using an image forming unit having a prescribed resolution, which is formed from a constant number of image forming elements (pixels) being discrete and being arranged in a spatially mutually fixed manner. For the improvement of the resolution along the outer and inner contours of the sectional areas of the object to be generated layer-wise in the sub-pixel range, a multiple illumination per layer is performed, which consists of a series of multiple images that are mutually shifted in the sub-pixel range in the image/construction plane, wherein a separate mask/bitmap is produced for each shifted image.