Projection Micro Stereolithography Surface Positioning Control
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Solution Overview
Problem
Current 3D printing technologies, particularly projection micro-stereolithography, face challenges in achieving precise control of surface positioning within a 10-micron tolerance, especially for the first few layers, due to limitations in mechanical accuracy and lack of effective methods for aligning transparent membranes or windows relative to the sample stage.
Innovation Solution
The use of a system comprising a lens, charge-coupled device (CCD), and a displacement sensor, such as a laser displacement sensor, to align and position surfaces with high accuracy, ensuring parallelism and precise distance control between substrates, along with the option of a sacrificial resin to create a parallel and tangential surface for improved dimensional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical machining and assembly methods are used for positioning substrates, then the manufacturing process is simple, but the positioning accuracy deteriorates to exceed 10 microns
Solution Approach 1:
The patent replaces mechanical alignment methods with optical measurement systems. A displacement sensor and lens system are used to optically measure and control the position and parallelism of substrates, achieving 10-micron accuracy without relying on mechanical machining precision. This substitutes mechanical positioning with optical field-based measurement and control.
Solution Approach 2:
The patent introduces a displacement sensor as an intermediary device between the substrates and the measurement system. This sensor acts as a mediator that converts physical displacement into measurable signals, enabling precise control of surface positioning and parallelism without direct mechanical contact or complex mechanical linkages.
2Manufacturing precision
If a transparent membrane is used for resin layer definition, then the resin can be contained effectively, but the positioning accuracy relative to the sample stage deteriorates to exceed 10 microns
Solution Approach 1:
The patent implements a feedback control system where a displacement sensor continuously measures the position of the transparent membrane relative to the sample stage. The measured position information is fed back to adjust and control the membrane positioning, ensuring it remains within 10-micron accuracy. This closed-loop feedback enables precise positioning despite the flexibility and difficulty of handling transparent membranes.
3Manufacturing precision
If the focus depth of the printing lens is increased to 100 microns or more, then the depth of field is improved, but the layer thickness control accuracy deteriorates to 100 microns or more
Solution Approach 1:
The patent introduces a displacement sensor as an intermediary measurement device that independently measures the position of surfaces with high precision. This sensor acts as a separate measurement channel that does not rely on the printing lens's focus depth, thereby achieving 10-micron layer thickness control accuracy independent of the optical system's depth of field limitations.
4Manufacturing precision
If three non-linear points are aligned sequentially with the displacement sensor, then the surface parallelism is improved within 10-micron tolerance, but the alignment time increases
Solution Approach 1:
The patent employs preliminary alignment actions where the displacement sensor is first calibrated and positioned before the actual substrate alignment process. The measurement system is prepared in advance with known reference points, allowing the sequential alignment of three non-linear points to be performed more efficiently. This preliminary preparation reduces the total alignment time while maintaining 10-micron parallelism accuracy.
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 precise control of surface positioning within a 10-micron tolerance, enhancing the dimensional accuracy of 3D printed samples by ensuring accurate alignment and uniformity of layers, thereby improving the representation of CAD models.
Implementation Method 1
The use of a system comprising a lens, charge-coupled device (CCD), and a displacement sensor, such as a laser displacement sensor
Implementation Method 2
a displacement sensor, such as a laser displacement sensor
Data Source
AI summary
Parallel surfaces on two substrates are established with specific distances of separation, typically within a 10-micron tolerance. In general, one surface is a surface of a transparent membrane or hard window. On one embodiment, the gap defined by the distance of the transparent membrane or hard window and the other surface used to precisely control the dimensions of layers in projection micro stereolithography, however the methods for establishing the relative positions of two surfaces can be adapted to other applications.