Stereolithography Light Source Segmentation for Layer Homogeneity

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Solution Overview

Problem

Stereolithography machines with a single light radiation source are limited in producing large three-dimensional objects due to reduced resolution and beam divergence, leading to inaccurate layer connections and potential gaps, which affect the structural integrity of the object.

Innovation Solution

A method for controlling two adjacent light radiation sources in a stereolithography machine, where each source activates specific sections of a layer's lines within a superimposition area, allowing for a comb-like connection pattern without superimposition, ensuring uniform thickness and stable connections between layer portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light radiation source is used in stereolithography, then the device complexity is reduced, but the manufacturing precision and resolution deteriorate when producing large three-dimensional objects due to beam divergence

Engineering Contradiction:
Improvenumber of light radiation sourcesVSAvoidresolution of three-dimensional object
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent divides the work surface into multiple zones, each illuminated by a dedicated light radiation source. Each source illuminates a specific portion of the work surface, avoiding beam divergence issues that affect the entire surface when using a single source. This segmentation allows large objects to be manufactured with maintained resolution across the entire surface area.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If the distance between the light radiation source and work surface is reduced, then the resolution is improved, but the field of action is limited and cannot accommodate large objects

Engineering Contradiction:
Improveresolution of objectVSAvoidfield of action on work surface
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

Multiple light radiation sources are positioned at optimized distances from the work surface, each covering a specific zone. This allows each source to operate at an optimal distance for high resolution while collectively covering a large field of action across the entire work surface through the segmented zones.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-point illumination approach to a distributed array of illumination sources across multiple dimensions. By positioning sources at different locations and orientations, the system expands the effective field of action while maintaining optimal source-to-surface distances for each local zone.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If multiple light radiation sources are used to produce larger objects, then the field of action is expanded, but the structural integrity deteriorates due to gaps and weak connections between layer portions

Engineering Contradiction:
Improvefield of action on work surfaceVSAvoidstructural integrity of object
Core Design Contradiction:
Area of stationary objectVSStrength

Solution Approach 1:

The patent applies different illumination strategies to different zones of the work surface. In superimposition areas where multiple sources meet, the system adjusts exposure parameters to ensure overlapping illumination creates strong connections rather than gaps. Each zone receives optimized illumination tailored to its specific geometric and structural requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the illumination parameters of multiple light radiation sources based on real-time feedback about layer formation quality. Exposure times, intensities, and positioning are continuously optimized to ensure proper bonding between portions illuminated by different sources, preventing gap formation and maintaining structural integrity.

Inventive Principle:
Principle #15Dynamics

4Volume of stationary object

If multiple light radiation sources are used, then larger objects can be produced, but the process time increases due to sequential activation requirements

Engineering Contradiction:
Improvesize of three-dimensional objectVSAvoidprocess time
Core Design Contradiction:
Volume of stationary objectVSProductivity

Solution Approach 1:

The patent implements periodic activation sequences for multiple light radiation sources, where sources are activated in coordinated cycles rather than continuously or sequentially. This periodic action allows overlapping exposure zones to be formed efficiently, with each source contributing to multiple layers in alternating cycles, thereby reducing total process time compared to strict sequential operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system maintains continuous useful action by coordinating multiple light radiation sources to operate in overlapping cycles. While one source is active, another is preparing or completing its cycle, ensuring that illumination coverage across the work surface remains continuous without idle periods, thus maximizing productivity while producing large objects.

Inventive Principle:
Principle #20Continuity of useful action

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 homogeneity of layer thickness and stability of connections, reducing process time and enabling the production of larger, high-resolution three-dimensional objects with improved structural integrity.

Implementation Method 1

Each layer of the object is obtained through solidification of a material in the liquid or paste state, which takes place through selective exposure to light radiation. Typically, the material is a plastic-based compound that polymerizes when reached by said light radiation.

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3174692B1Improved method for controlling the activity of at least two light radiation sources belonging to a stereolithography machine.
Publication Date: 2020.06.24 DWS SRL
  • EP3174692B1 patent drawingFigure 1a~1b
  • EP3174692B1 patent drawingFigure 2
  • EP3174692B1 patent drawingFigure 3

AI summary

The invention is a method for controlling the activity of two light radiation sources (2, 3) belonging to a stereolithography machine (1) and suited to act at the level of a portion (104) of a superimposition area (101) defined on the work surface (100) of the stereolithography machine (1) for the production of a three-dimensional object (200) through stereolithography. For each one of the lines (210) with generic length L that define each layer (201) of the three- dimensional object (200) within the portion (104), the method provides for activating: - a first light radiation source (2) for a first section (211) of the line (210) having length X; - a second light radiation source (3) for the remaining second section (212) of the line (210) having length Y, wherein the value X of the first section (211) is selected within the interval 0 <= X <= L and wherein V is calculated as equal to L - X.