Web Property Measurement Using Intermittent Chopping
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Solution Overview
Problem
Current web property measurement systems face challenges in accurately measuring properties of quickly moving, fluttering webs in harsh environments due to measurement errors caused by temperature drift and Planckian radiation, which are not adequately addressed by traditional continuous chopping methods.
Innovation Solution
The system performs a single chop at each edge of the sheet during web production, measuring edge temperature and thermal radiation to derive correction factors for Planckian radiation and electronic offset drift, allowing for precise web property measurement without interrupting the radiation beam, thereby improving signal-to-noise ratio and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional continuous chopping methods are used to correct for temperature drift and Planckian radiation, then measurement accuracy is improved, but signal intensity is reduced and measurement bandwidth is limited
Solution Approach 1:
The patent applies periodic action by using intermittent chopping instead of continuous chopping. The beam chopper operates in a periodic manner, chopping the beam only at specific intervals (e.g., at the edges of the web or at predetermined time intervals), allowing the beam to remain open during most of the measurement period. This periodic chopping corrects for temperature drift and Planckian radiation while maintaining higher signal intensity and bandwidth compared to continuous chopping.
Solution Approach 2:
The patent implements continuity of useful action by minimizing the time the beam is chopped. Instead of continuous chopping that blocks the beam throughout the measurement cycle, the system uses intermittent chopping where the beam is open for the majority of the measurement period. This allows the useful measurement action to continue uninterrupted, maintaining high signal intensity and measurement bandwidth while still providing necessary corrections for temperature effects.
2Measurement precision
If traditional continuous chopping methods are used to correct for temperature drift and Planckian radiation, then measurement accuracy is improved, but measurement bandwidth is reduced
Solution Approach 1:
The patent uses periodic action with intermittent chopping that occurs only at specific intervals rather than continuously. This allows the measurement system to maintain high bandwidth by minimizing the time the beam is blocked, while still providing periodic corrections for temperature drift and Planckian radiation effects through the intermittent chopping action.
Solution Approach 2:
The patent ensures continuity of useful measurement action by keeping the beam open for the majority of the measurement period. The intermittent chopping approach allows the measurement system to operate at high speeds without the bandwidth limitations imposed by continuous chopping, while still achieving accurate measurements through periodic corrections.
3Measurement precision
If multiple spatially separated sensors are used to measure different spectral bands simultaneously, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the measurement system into multiple sensors, each detecting a specific spectral band. Instead of using a single complex sensor to measure all wavelengths, the system segments the spectral measurement function across multiple simpler sensors, each optimized for a specific wavelength range. This segmentation approach improves measurement accuracy by allowing simultaneous measurement of multiple spectral bands while keeping individual sensor complexity manageable.
Solution Approach 2:
The patent implements multi-functionality by having a single sensor detect multiple spectral bands through the use of a beam chopper that modulates the beam at different frequencies for different wavelengths. Alternatively, multiple sensors share common optical paths and processing systems, allowing the system to achieve the functionality of multiple dedicated sensors while reducing overall device complexity through shared components.
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 high-precision measurement of short-term material property variations on fast-moving webs by correcting for thermal radiation and electronic drift, enhancing measurement accuracy and bandwidth without reducing radiation flux, allowing for higher sampling rates than traditional beam choppers.
Implementation Method 1
measuring temperature of the web while the source of measuring radiation is interrupted
Implementation Method 2
applying the correction factors at each of the consecutive points across the web to correct for Planckian radiation contained in radiation representative of the at least one property of the web received at the consecutive points across the web
Implementation Method 3
Infrared spectroscopic sensors are common monitoring devices for such control systems. These sensors measure the absorption of infrared radiation at specific wavelength bands, indicating a specific property's presence and/or magnitude.
Data Source
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Figure 3
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AI summary
Web measurement system monitors properties of a web during manufacture without chopping measuring radiation during web measurement. A single chop is performed at each sheet edge or every n? sheet edge to measure edge temperature and edge thermal radiation for correction for Planckian radiation. Correction factors, including Planckian radiation correction factors, are derived for each point in a web profile. The measuring system also enables derivation of correction factors during operation in a single point and similar machine operating modes.