Lithography-Based 3D Printing With Encoder-Synchronized Exposure
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Solution Overview
Problem
Existing additive manufacturing (AM) processes for polymers face challenges in achieving high surface quality, small feature resolution, and thermo-mechanical material properties, particularly with stereolithography (SLA) systems, due to limitations in resin accuracy, chemical stability, and viscosity issues, which hinder industrial and mass production applications like dental appliances and aligners.
Innovation Solution
A 3D printing system with a dynamic light engine and material transport unit allows for precise control of exposure time and synchronization of light patterning with relative movement, enabling high accuracy and large building areas, using a flexible carrier film and controlled temperature management to handle lowly cross-linked photopolymer networks with strong secondary bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If vat-based stereolithography is used with large resin vats, then large building areas are achieved, but manufacturing precision deteriorates due to optical limitations and timing constraints of laser scanning systems
Solution Approach 1:
The patent divides the large building area into multiple smaller exposure fields that can be processed sequentially. The light source scans across the resin surface in a controlled manner, exposing one region at a time according to a predetermined pattern. This segmentation allows the system to maintain high precision for each small region while achieving large overall building areas through systematic progression across multiple fields.
2Manufacturing precision
If resin layer thickness is reduced for high resolution, then manufacturing precision improves, but productivity deteriorates due to increased number of layers and exposure time
Solution Approach 1:
The patent implements continuous scanning of the light source across the resin surface without interruption. The light source moves continuously according to a predetermined pattern, exposing resin layers in a seamless manner. This continuous action eliminates idle time between exposure steps and maintains consistent processing speed throughout the entire printing process, thereby maintaining high productivity even with thin resin layers requiring high resolution.
3Ease of manufacture
If photopolymer resin is stored in large vats for extended periods, then ease of manufacture improves, but reliability deteriorates due to chemical instability and degradation
Solution Approach 1:
The patent extracts only the necessary amount of photopolymer resin from the bulk vat and processes it layer by layer. The system applies resin to the building platform in thin, controlled layers that are immediately exposed and cured. This extraction approach minimizes the amount of resin that remains in the vat for extended periods, thereby maintaining chemical stability and reliability while still enabling large building areas through the accumulation of multiple thin layers.
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
The system achieves high printing accuracy, stability, and flexibility, producing 3D structures with excellent thermo-mechanical properties suitable for industrial applications, overcoming viscosity and reactivity challenges, and supporting continuous additive manufacturing.
Implementation Method 1
Different light sources are typically used in order to induce photopolymerization of the liquid photopolymer resin layer
Data Source
AI summary
A device for the lithography-based additive manufacturing of three-dimensional structures may comprise a building platform defining a building plane, a light engine designed for the dynamic patterning of light in an exposure field of said light engine, a material transport unit comprising a first drive mechanism for transporting a material layer across the exposure field, a second drive mechanism for causing relative movement of the light engine and the building platform along a displacement path extending parallel to the building plane, a linear encoder for sensing a position and/or a velocity of the light engine relative to the building platform, and/or one or more control units configured to adjust the feeding rate of a pattern data feeder based on the position or the velocity sensed by the linear encoder.