Fiber Orientation Imaging for High-Speed Paper Webs
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Solution Overview
Problem
Existing methods for determining fiber orientation in fibrous material webs, such as paper and cardboard, fail to provide accurate measurements at high production speeds due to blurring and insufficient image resolution, leading to inaccurate fiber orientation calculations.
Innovation Solution
A method involving extremely short exposure times (up to 1 μs) and high-resolution imaging (pixel edge length <20 μm) combined with specific illumination parameters (wavelengths between 450 nm and 780 nm, narrowband illumination, and angled light incidence) to capture clear digital images of the fibrous material web.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical systems with longer exposure times are used, then the device complexity and cost are reduced, but the measurement precision deteriorates due to blurring at high production speeds
Solution Approach 1:
The patent applies periodic pulsed illumination with exposure times of 1 microsecond or less to freeze the motion of the fibrous material web during imaging. This ultra-short periodic illumination action captures sharp images without motion blur, enabling precise fiber orientation measurements at high production speeds while managing the complexity through controlled temporal illumination patterns
Solution Approach 2:
The patent changes the temporal parameter of illumination from continuous to ultra-short pulses (≤1 μs), and adjusts the spectral parameters by selecting specific wavelength ranges (450-780 nm). These parameter changes enable clear imaging of moving webs without requiring excessively complex hardware, balancing measurement precision with device complexity
2Productivity
If production speed is increased, then productivity improves, but measurement precision deteriorates due to motion blurring
Solution Approach 1:
The patent uses ultra-short illumination pulses (≤1 μs) to rush through the exposure process so quickly that the moving fibrous web does not appreciably move during the measurement. This allows high production speeds to be maintained while obtaining sharp, blur-free images for accurate fiber orientation determination
Solution Approach 2:
By implementing periodic pulsed illumination synchronized with the web motion, the system captures measurements at critical moments when the web position is stable, enabling high-speed production to continue without sacrificing measurement accuracy
3Measurement precision
If image resolution is increased to reduce pixel edge length, then measurement precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent achieves high measurement precision by changing the temporal parameter (ultra-short exposure) rather than solely relying on increasing spatial resolution. The combination of ≤1 μs exposure with moderate resolution (pixel edge length <20 μm) provides accurate fiber orientation data without requiring excessively complex high-resolution imaging systems
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 reliable fiber orientation measurements even at speeds greater than 1200 m/min, providing accurate fiber orientation data for improved production control and reducing paper defects like curls and jams.
Implementation Method 1
illumination means for illuminating an area A of the fibrous material web
Implementation Method 2
a camera for recording a digital image of the illuminated area of the fibrous material web
Data Source
AI summary
An apparatus and an associated method determine the fiber orientation of a moving fibrous web, in particular a paper, cardboard or cellulose web. An illumination device illuminates an area of the fibrous web and a camera records a digital image of the illuminated area of the fibrous web. The illumination device is configured to illuminate the fibrous web for a period of time of 1 μs or less and the camera is configured in such a way that the edge length of a pixel corresponds to no more than 20 μm, in particular no more than 10 μm.