Reference-Layer Sensing for Stereolithographic Layer Separation

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Solution Overview

Problem

Stereolithography processes face long processing times due to layer separation, inability to detect exposure errors, and issues with adhering to substrates, with existing force sensors only measuring total separation forces and not individual layer forces, leading to unreliable production of multiple bodies.

Innovation Solution

A method using measurement radiation coupled into a reference layer for internal reflection, detected by a sensor with spatial and temporal resolution, allowing continuous monitoring of the layer production process and detection of adhesive forces through deformation of the reference layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If force sensors are used to measure separation forces, then the total separation force can be recorded, but the separation force of specific components or layers cannot be identified

Engineering Contradiction:
Improveseparation force measurementVSAvoidindividual layer force information
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the measurement function by positioning individual force sensors on each component layer rather than using a single total force sensor. This allows the measurement system to distinguish and record separation forces for specific components or layers, resolving the information loss problem while maintaining the ability to measure total separation force through summation of individual sensor readings.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If layer separation is performed manually or with simple movement, then the process is simple, but long processing times and waiting times occur

Engineering Contradiction:
Improvelayer separation processVSAvoidproduction speed
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent implements feedback control by using force sensors to detect separation forces in real-time during the layer separation process. The control system monitors the separation force signals and automatically determines when separation is complete, enabling automated control that reduces manual intervention time and waiting periods while maintaining simple operational principles through automated decision-making based on force threshold detection.

Inventive Principle:
Principle #23Feedback

3Device complexity

If exposure errors are not detected, then the process is simple, but production reliability is compromised

Engineering Contradiction:
Improveexposure monitoring systemVSAvoidproduction reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent incorporates feedback mechanisms through force sensors that monitor separation forces and provide real-time information about exposure quality. By analyzing the separation force characteristics, the system can detect exposure errors such as incomplete curing or improper layer formation, automatically identifying when rework is needed without significantly increasing device complexity through the use of existing sensor technology and signal processing.

Inventive Principle:
Principle #23Feedback

4Productivity

If multiple bodies are produced simultaneously, then productivity increases, but it is unclear whether all bodies will be built reliably and completely

Engineering Contradiction:
Improvenumber of bodies producedVSAvoidbuild quality consistency
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies segmentation by positioning individual force sensors on each component layer, enabling independent monitoring of separation forces for multiple bodies produced simultaneously. This segmented measurement approach allows the control system to track the build quality and separation status of each individual body, ensuring consistent and reliable production across multiple components without compromising quality for the sake of increased productivity.

Inventive Principle:
Principle #1Segmentation

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

Enables precise, continuous, and fast production of three-dimensional bodies with reduced waiting times, allowing simultaneous production of multiple bodies and monitoring of the polymerization process.

Implementation Method 1

measurement radiation is coupled into a reference layer and remains predominantly within the reference layer due to internal reflection

Methodology Applied
Scientific EffectInternal reflection: Total Internal Reflection

Implementation Method 2

a radiation source for generating the specific radiation required for curing; a photosensitive material is cured by radiation

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3825105B1Measuring method for creating a three-dimensional body
Publication Date: 2025.10.22 STADLMANN KLAUS
  • EP3825105B1 patent drawingFigure 1
  • EP3825105B1 patent drawingFigure 2
  • EP3825105B1 patent drawingFigure 3

AI summary

The invention relates to a method for producing a three-dimensional body (60, 70) in a stereolithographic process, wherein a photosensitive material (9) is cured by radiation from a radiation source (60), characterized in that the exothermic solidification processes triggered by the radiation source (60) are detected by a sensor (5) in order to at least partially detect the polymerization state of the formed layer (30, 31, 32) and, by recording the radiation through the sensor (5), also to gain an inference about the possible separation process of the produced layer (30, 31, 32).