Planar Plotting Mask for Stereolithography
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Solution Overview
Problem
Conventional stereolithographic methods face challenges in achieving high building accuracy, productivity, and surface quality due to issues like low productivity, high costs of UV laser systems, and difficulties in manufacturing large-size objects with uniform strength and accuracy.
Innovation Solution
A stereolithographic method and apparatus that uses a planar plotting mask capable of continuous movement, dynamically changing its mask image to form optically-cured resin layers with predetermined cross-sectional profiles, ensuring equal light intensity on boundary areas and staggering their positions to prevent lines, streaks, and ridges, while using an inexpensive light source like an ordinary UV lamp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spot-shaped UV laser beam is used for stereolithography, then high building accuracy can be achieved, but the productivity is low and the apparatus cost is extremely high
Solution Approach 1:
The patent divides the continuous light beam into discrete linear segments using a linear exposure mask with multiple optical shutters. This segmentation allows simultaneous exposure of multiple lines across the resin surface, transforming the sequential spot-by-spot curing into parallel line-by-line curing, thereby dramatically increasing building rate while maintaining precision through controlled shutter positioning.
Solution Approach 2:
The invention transitions from one-dimensional spot scanning to two-dimensional linear array exposure by arranging optical shutters in a line. This dimensional change enables simultaneous exposure of multiple locations across the resin surface, converting the time-consuming sequential process into a parallel operation that maintains accuracy while boosting productivity.
2Productivity
If a linear exposure mask with optical shutters is used to form linear optically-cured sections, then the building rate increases compared to spot laser, but lines, streaks, and ridges appear on the surface
Solution Approach 1:
The patent applies different exposure strategies to different regions of the resin surface. By selectively controlling which optical shutters are activated and adjusting their exposure parameters locally, the system optimizes curing for each specific area, preventing the formation of surface defects while maintaining high building rate through parallel exposure of multiple regions.
Solution Approach 2:
The invention dynamically adjusts the exposure parameters of individual optical shutters during the curing process. By making real-time adjustments to shutter positioning, exposure duration, and light intensity based on the specific requirements of each linear section, the system prevents surface defects while maintaining high productivity through coordinated dynamic control of multiple exposure zones.
3Productivity
If the photo-mask scan speed is increased to improve productivity, then the building rate increases, but insufficient optical curing occurs on a per-line basis
Solution Approach 1:
The patent implements continuous exposure of multiple linear sections simultaneously across the resin surface using an array of optical shutters. This continuous parallel exposure eliminates the intermittent scanning motion, ensuring that each line receives sufficient light energy for complete curing while the overall process maintains high speed through simultaneous multi-line exposure, thereby achieving both productivity and curing completeness.
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 enables the production of high-quality, large-size stereolithographic objects with superior appearance, dimensional accuracy, and uniform strength at a higher building rate and productivity, without the need for expensive UV laser systems.
Implementation Method 1
exposing a surface of a photocurable resin composition by way of a planar plotting mask under control to thus form an optically-cured resin layer having a predetermined cross-sectional profile pattern
Data Source
AI summary
A method and an apparatus includes using a planar plotting mask which can continuously change a mask image; continuously moving the planar plotting mask with reference to the surface of the photocurable resin composition and exposing the surface of a photocurable resin composition to light by way of the planar plotting mask while continuously changing a mask image of the planar plotting mask in accordance with a cross-sectional profile pattern of an optically-cured resin layer to be formed and in synchronism with movement of the planar plotting mask, to thus form an optically-cured resin layer having a predetermined cross-sectional profile pattern; and performing building operation such that boundary areas among adjacent plotted areas in the optically-cured resin layer become unnoticeable in a finally-obtained stereolithographic three-dimensional object.