Electrostatic Probe Mapping for Conductive Web Bagginess
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Solution Overview
Problem
The manufacturing of photovoltaic devices is hindered by bagginess in conductive webs, which results in non-uniform tension, leading to issues like undesirable aesthetics, coating variations, and increased manufacturing costs due to the need for complex steering mechanisms and frequent scrapage of defective webs.
Innovation Solution
A method and apparatus using electrostatic probes to monitor and map the tension levels of a moving conductive web, determining bagginess by measuring induced current or voltage and comparing it to reference values, allowing for real-time feedback to optimize the deposition process and prevent web defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tension is applied to the conductive web during the coating process, then the web can be processed and coated, but the tension becomes non-uniform in the cross web direction causing bagginess
Solution Approach 1:
The electrostatic probe system performs preliminary detection of web bagginess before the coating process begins. By measuring the capacitance between the probe and the web surface, the system identifies areas of non-uniform tension in advance, allowing operators to adjust web handling or tensioning mechanisms before coating, thus preventing defect formation while maintaining productivity
Solution Approach 2:
The system provides real-time feedback on web tension uniformity through continuous capacitance measurements. The electrostatic probe monitors bagginess levels during web processing, and this information can be fed back to control systems to dynamically adjust tensioning mechanisms, ensuring uniform tension is maintained throughout the coating process
2Manufacturing precision
If complex steering mechanisms are used to compensate for bagginess, then web uniformity can be improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent replaces complex mechanical steering mechanisms with an electrostatic detection system. Instead of using mechanical devices to physically steer or tension the web, the system uses electrostatic probes to detect bagginess and provides information for process control, significantly reducing mechanical complexity while achieving the same uniformity improvement
Solution Approach 2:
The electrostatic probe acts as an intermediary between the web and the control system. Rather than directly mechanically adjusting the web, the probe measures capacitance changes caused by bagginess and transmits this information to control systems, which then make adjustments based on the data, reducing the need for complex direct mechanical steering mechanisms
3Manufacturing precision
If frequent scrapage of defective webs is performed to maintain quality, then product quality is improved, but productivity and cost efficiency deteriorate
Solution Approach 1:
The electrostatic probe system performs preliminary detection of bagginess defects before they propagate through the coating process and become irreparable defects. By identifying problematic areas early in the web processing sequence, the system allows for corrective actions to be taken on specific sections rather than requiring scrapage of entire webs, thus maintaining quality while improving productivity
Solution Approach 2:
Instead of discarding entire webs when defects are detected, the system enables selective recovery and correction. By precisely locating bagginess areas through capacitance measurement, operators can apply localized corrections or adjustments to specific problem sections while salvaging the rest of the web, reducing scrapage rates and improving overall manufacturing efficiency
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 accurate, contact-less, and continuous monitoring of web tension and bagginess, reducing scrapage and manufacturing costs by ensuring uniform deposition and improving the quality of photovoltaic devices.
Implementation Method 1
measuring a current or voltage in the at least one electrostatic probe induced by a capacitance between the conductive web and the at least one electrostatic probe
Data Source
AI summary
A method for testing a conductive web includes moving a conductive web past at least one electrostatic probe, providing an alternating current or voltage which generates an alternating current to the at least one electrostatic probe, measuring a current or voltage in the at least one electrostatic probe induced by a capacitance between the conductive web and the at least one electrostatic probe, comparing the measured current or voltage to a reference value, and determining a level of bagginess of the conductive web based on the step of comparing.