Vat Polymerization Mask Scanning for Reduced Resin Heating
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Solution Overview
Problem
The heating of photo-curable liquid resin during three-dimensional printing due to exothermic curing reactions and mask irradiation leads to temperature exceedance, causing resin curing defects and necessitating process halts or resin circulation for cooling, which reduces throughput.
Innovation Solution
A vat polymerization printer system with a mask having individually controllable transparent and opaque pixels, controlled by a processor to selectively illuminate regions of the mask, minimizing heating by reducing the exposure of opaque pixels and optimizing scan paths to reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light source continuously irradiates the mask to maintain high printing throughput, then productivity is improved, but the mask and resin temperature increases causing curing defects
Solution Approach 1:
The mask is divided into multiple individually controllable pixels that can be independently switched between transparent and opaque states. This segmentation allows selective illumination of only the regions requiring curing, reducing overall heat generation while maintaining printing throughput in critical areas.
Solution Approach 2:
The system employs periodic scanning of the light beam across the mask rather than continuous stationary illumination. The beam scanner moves the light source in a scanning pattern, illuminating different pixel regions at different times, which distributes heat generation over time and reduces peak temperatures while maintaining effective curing.
2Temperature
If the printing process is halted periodically to cool the resin, then temperature control is improved, but productivity decreases
Solution Approach 1:
The system performs preliminary selective illumination by activating only the specific pixels corresponding to the cross-section being printed, before the resin can overheat. This preliminary targeted action prevents heat accumulation in non-curing regions, eliminating the need for periodic process halts for cooling.
Solution Approach 2:
Different regions of the mask receive different illumination treatments - only the regions corresponding to transparent pixels are illuminated, while opaque pixel regions remain unilluminated. This local quality differentiation ensures that heat is generated only where curing is needed, maintaining temperature control without reducing throughput.
3Temperature
If a resin circulatory system is used to cool the heated resin, then temperature control is improved, but device complexity increases
Solution Approach 1:
The invention extracts and removes the need for complex external cooling systems by addressing the root cause of heating - selective illumination of opaque pixels. By taking out the problematic broad illumination and replacing it with targeted pixel-level control, the system eliminates the requirement for resin circulatory cooling infrastructure.
Solution Approach 2:
The mask's pixel elements perform the dual function of defining the print pattern and controlling heat generation. The same transparent/opaque pixel configuration that defines the cross-section geometry also serves to limit heat generation to only necessary regions, making the system self-regulating without external cooling intervention.
4Manufacturing precision
If the light beam diameter is reduced to match pixel dimensions for precise illumination, then manufacturing precision is improved, but the scanning time increases reducing productivity
Solution Approach 1:
The system employs a dynamic scanning approach where the light beam rapidly moves across the mask in a scanning pattern. This dynamic motion allows the use of a relatively large beam diameter without sacrificing precision, as the beam's position is continuously updated to match the required pixel pattern, maintaining both speed and accuracy.
Solution Approach 2:
The beam scanning process maintains continuous useful action by keeping the light source constantly active and moving it through the required pattern. This continuous scanning eliminates idle time between illuminating different pixels, maintaining high productivity while achieving precise spatial control through the scanning motion rather than beam size reduction.
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
Reduces resin heating by selectively illuminating transparent pixels, minimizing the exposure of opaque pixels, thereby maintaining resin temperature within safe limits and enhancing printing throughput without cooling interruptions.
Implementation Method 1
The present invention relates to the printing of three-dimensional objects by photo-curing a liquid resin
Implementation Method 2
the irradiation of a mask by a light source, typically an ultra-violet (UV) light source, also causes heating of the mask
Implementation Method 3
A beam scanner is configured to scan the light beam across the mask
Data Source
AI summary
In a vat polymerization printer, a beam scanner scans a light beam across a mask and into a tank containing a photo-curable resin. The mask has pixels configurable to be individually transparent or opaque to portions of the light beam, which has a diameter greater than a cross-sectional dimension of the pixels of the mask. During an exposure time duration, a first subset of the pixels are controlled to be transparent at locations corresponding to the cross section of a three-dimensional object to be printed, while a second subset of the pixels are controlled to be opaque at locations not corresponding to the cross section of the three-dimensional object. The beam scanner is controlled to scan the light beam across the mask such that the light beam is always incident on at least one of the pixels of the mask that are controlled to be transparent.