Non-Contact Capacitive Resin Level Sensing in Additive Fabrication
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Solution Overview
Problem
Existing additive fabrication technologies face challenges in monitoring and controlling the temperature and fluid level of photopolymer resin within containers without increasing the complexity or cost of the container, as traditional sensors can contaminate or misalign with the resin and require extensive calibration for varying temperatures.
Innovation Solution
An additive fabrication device with non-contact capacitive sensors and heaters that monitor and control the resin level and temperature externally, allowing for a feedback loop to maintain a constant resin temperature and level without modifying the container, using multiple capacitive sensing regions to compensate for the low dielectric constant of photopolymer resin and variable container positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional contact sensors are used to monitor resin level and temperature, then measurement capability is improved, but sensor contamination and misalignment with resin occurs
Solution Approach 1:
The patent introduces an air gap as an intermediary space between the capacitive sensors and the photopolymer resin. This allows the sensors to measure resin level and temperature through non-contact means, eliminating contamination and misalignment issues while maintaining measurement capability. The air gap serves as a mediator that enables sensing without direct contact.
Solution Approach 2:
The patent replaces traditional mechanical contact sensors with non-contact capacitive sensors. This substitution eliminates the need for physical contact between sensors and resin, thereby preventing contamination and misalignment while preserving the ability to monitor resin level and temperature accurately.
2Measurement precision
If sensors are integrated into the container to enable monitoring, then measurement capability is improved, but container complexity increases
Solution Approach 1:
The air gap acts as an intermediary that enables sensing functionality without requiring sensor integration into the container. The external capacitive sensors can measure fluid level through the air gap and container wall, maintaining measurement capability while keeping the container structure simple and unchanged.
Solution Approach 2:
The container serves multiple functions: it holds the photopolymer resin and simultaneously acts as a dielectric medium that enables capacitive sensing. The container's existing structure is utilized for both its primary containment function and as part of the sensing mechanism, eliminating the need for additional sensor integration components.
3Measurement precision
If multiple capacitive sensors are used to compensate for low dielectric constant, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the sensing function into multiple discrete capacitive sensors positioned at different locations. Each sensor contributes to the overall measurement, and their combined data provides accurate resin level detection despite the low dielectric constant of the photopolymer resin. The segmentation of sensing zones enables precise measurement through spatial distribution.
Solution Approach 2:
The patent utilizes the dielectric properties of multiple materials (air, container wall, resin) and changes the sensing parameters by using multiple capacitive sensors with different positions and configurations. This allows compensation for the low dielectric constant of the resin by leveraging the combined capacitive effects of the entire sensing path.
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 the use of low-cost, replaceable resin containers with precise temperature and fluid level control, reducing structural instabilities and inaccuracies in fabricated objects by maintaining optimal resin conditions during the additive fabrication process.
Implementation Method 1
three or more capacitive sensors coupled to the additive fabrication device, and an air gap between said container and said sensors
Implementation Method 2
heaters that monitor and control the resin level and temperature externally
Implementation Method 3
allowing for a feedback loop to maintain a constant resin temperature and level
Data Source
AI summary
According to some aspects, an additive fabrication device is provided comprising a container removably attached to the additive fabrication device, and a detector configured to sense a fluid level of photopolymer resin within the container, wherein said detector does not contact said container.