SLM Mask Illumination for 3D Printing Curing Control

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Solution Overview

Problem

Existing methods for producing three-dimensional objects using photopolymers with SLM technology face issues of inhomogeneous light output distribution, variable light intensity affecting entire images, and limited resolution and fine adjustment, leading to inaccuracies and defects in the curing process.

Innovation Solution

The method involves using multiple digital masks (bitmaps) for selective exposure control at the pixel level, allowing for precise control of voxel curing depth and intensity, enabling overexposure in specific areas and optimizing support structures, while using gray value and color adjustments to refine the curing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If mask projection using SLM technology is used to expose entire cross-sectional area at once, then productivity is improved, but manufacturing precision deteriorates due to inhomogeneous light output distribution

Engineering Contradiction:
Improveexposure speedVSAvoidcuring homogeneity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent divides the cross-sectional area into multiple sub-areas corresponding to different pixel groups in the SLM device. Each pixel group receives independently controllable light intensity, allowing selective adjustment of exposure parameters for different regions to compensate for optical inhomogeneities and achieve uniform curing across the entire area.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If light intensity is increased to improve curing depth, then manufacturing precision is improved, but object-generated harmful factors worsen due to material shrinkage

Engineering Contradiction:
Improvecuring depth controlVSAvoidmaterial shrinkage
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies different light intensities to different spatial regions within the cross-sectional area based on local requirements. Areas requiring deeper curing receive higher intensity, while other areas use lower intensity to minimize shrinkage. This localized control allows optimization of curing depth without uniformly increasing shrinkage across the entire object.

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If multiple digital masks are used for selective exposure control, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvevoxel curing controlVSAvoidexposure system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical mask changing systems with a digital imaging device (SLM) that can dynamically generate and switch between multiple digital masks (bitmaps) electronically. This substitution maintains high manufacturing precision through selective pixel-level control while reducing mechanical complexity and improving response speed.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 accuracy, resolution, and homogeneity of the curing process, improving the quality of three-dimensional objects by allowing precise control over voxel depth and surface finish, reducing material shrinkage, and optimizing support structures.

Implementation Method 1

producing a three-dimensional object by solidifying a material that can be solidified under the action of electromagnetic radiation by means of energy input via an imaging unit

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP1849586B1Device and method for creating a three dimensional object using mask illumination
Publication Date: 2015.09.23 ENVISIONTEC GMBH DE
  • EP1849586B1 patent drawingFigure 1A~1C
  • EP1849586B1 patent drawingFigure 2A~2C
  • EP1849586B1 patent drawingFigure 3A~3B

AI summary

Device and method for producing a three-dimensional object (40) by solidifying a solidifiable material under the influence of electromagnetic radiation by means of energy input via an imaging unit having a specific number of discrete imaging elements, pixels. The energy input related to a specific cross-sectional area of ​​the three-dimensional object is controlled by exposure using several successive rasterized masks (Bitmap 1 and Bitmap 2).