Polarized Light Sensor for Material Web Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sensors fail to reliably capture the position of a moving material web, especially under unfavorable conditions such as low contrast between markings and the web due to coatings like clear varnish.
Innovation Solution
The sensor employs light sources that emit polarized emission light, varying polarization states to enhance contrast, and uses polarization filters to optimize detection, allowing reliable scanning of markings on moving material webs even when traditional illumination methods fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional illumination methods are used, then the sensor structure is simple, but the detection reliability deteriorates under unfavorable conditions such as low contrast markings or coated material webs
Solution Approach 1:
The patent applies parameter changes by varying the polarization state of the emission light to optimize contrast for different material web conditions. Multiple light sources with different polarization states (parallel and perpendicular to the material web plane) are used, and their emission powers are varied to achieve optimum contrast for detecting markings under various unfavorable conditions such as clear varnish coatings.
Solution Approach 2:
The patent introduces polarization filters as intermediary elements between the light sources and the material web, and between the material web and the light detector. These polarization filters mediate the interaction by selectively transmitting or blocking light based on polarization state, thereby enhancing the contrast of detected markings without requiring fundamental changes to the overall sensor structure.
2Measurement precision
If the emission power of light sources is varied to optimize contrast, then the detection precision improves, but the control complexity increases
Solution Approach 1:
The control system varies the emission power of individual light sources based on the polarization state required for optimal detection. By selectively activating and adjusting the intensity of light sources with different polarization characteristics, the system achieves precise adaptation to different material web conditions (e.g., marked vs. unmarked, coated vs. uncoated) without requiring complex real-time analysis.
3Illumination intensity
If polarization filters are added to optimize detection, then the contrast enhancement improves, but the device complexity increases
Solution Approach 1:
Polarization filters are introduced as intermediary optical elements that selectively transmit or block light based on polarization state. These filters are positioned between the light sources and the material web, and between the material web and the detector, to enhance the contrast of reflected or transmitted light from markings while maintaining a relatively simple overall optical system architecture.
4Adaptability or versatility
If multiple light sources with different polarization states are used, then the adaptability to different material conditions improves, but the device complexity increases
Solution Approach 1:
The sensor system achieves universality by incorporating multiple light sources that can emit light with different polarization states (parallel and perpendicular to the material web plane). This multi-functional light source configuration allows the same sensor to effectively detect markings on various material web conditions including clear varnish coatings, different substrate materials, and various marking types, without requiring separate specialized sensors for each condition.
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 reliable detection of material web positions and markings by leveraging polarization-dependent reflection properties, effectively overcoming challenges posed by low contrast and coatings, ensuring accurate scanning under difficult conditions.
Implementation Method 1
the emission light of the at least one of the light sources is polarized parallel to the plane of the material web, while the emission light of the at least one other light source is polarized perpendicular to the plane of the material web
Implementation Method 2
Light reflected thereby is reflected by the beam splitter and guided to a detector
Implementation Method 3
If light strikes the material web exactly at the Brewster angle, light having a polarization direction which is parallel to the material web is not reflected
Implementation Method 4
at least one polarization filter is provided between the at least one light source and the at least one light detector
Implementation Method 5
The light reflected by the material web is captured by a light detector and converted into an electrical signal
Data Source
AI summary
A sensor (1) serves for capturing the moving material web (2). It has light sources (4, 4′) and at least one light detector (10). The light sources (4, 4′) generate emission light (5) having different polarization. The polarization state of the emitted light can be influenced by selecting or mixing the emission light (5) of the light sources (4, 4′). Markings such as for example metal strips (13) in the material web (2) can thus be captured with the light detector (10) without problem.