Double Back Scanner for Web Thickness Measurement
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Solution Overview
Problem
Existing web measurement technologies, such as O-frame and C-frame scanners, face challenges in maintaining stable registration and distance due to inherent registration issues and mechanical wear, leading to degradation in measurement accuracy, especially when dealing with wide webs and varying geometries.
Innovation Solution
A double back scanner apparatus with a C-frame configuration and linear slide for cross-web movement, utilizing non-contact displacement sensors like capacitive sensors, and optionally incorporating additional sensors for temperature, moisture, and color measurements, to ensure precise thickness and basis weight measurement by guiding the web through a measurement channel with overlapping sections for enhanced signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If O-frame thickness measurement gauge scanners are used, then thickness and basis weight can be measured, but fixed distance and registration of sensor pairs are difficult to achieve and maintain stably
Solution Approach 1:
The patent replaces mechanical contact sensors with non-contact sensors (optical, capacitive, or inductive sensors) that measure thickness without physical contact. This eliminates mechanical wear and tear on translating elements, thereby maintaining stable registration and distance over time while preserving measurement precision.
Solution Approach 2:
The patent employs a multi-functional sensor system that can perform both thickness measurement and registration verification functions. The non-contact sensors are capable of measuring thickness while also providing feedback on their positional relationship to the web, enabling simultaneous optimization of both measurement precision and registration stability.
2Area of stationary object
If web width increases, then more material can be processed, but difficulty to maintain registration and distance of supporting structures increases
Solution Approach 1:
The patent divides the measurement system into multiple independent sensor units distributed across the web width. Each sensor unit maintains its own registration independently, and the system aggregates measurements from all units to provide comprehensive coverage of the wide web, thereby maintaining registration quality across the entire width.
Solution Approach 2:
By using non-contact sensors, the patent eliminates the need for mechanical supporting structures that span the web width. This removes the fundamental constraint that prevents maintaining registration over wide distances, allowing the system to accurately measure wide webs without degradation in registration quality.
3Ease of operation
If C-frame scanning gauges are used, then edge measurement can be performed, but positional stability of sensor pairs deteriorates with increased beam length
Solution Approach 1:
The patent replaces the C-frame mechanical structure with non-contact sensors that can be positioned close to the web edge without requiring long cantilevered beams. This eliminates the beam length limitation that causes positional instability, enabling accurate edge measurement while maintaining sensor positional stability.
4Reliability
If off-line excursion is required, then sensors can be re-standardized, but spatial constraints are violated and process envelope is exceeded
Solution Approach 1:
The patent uses non-contact sensors that can be re-standardized without requiring physical retraction or excursion from the web. The sensors maintain continuous contactless measurement capability, allowing re-standardization to occur in-line without violating spatial constraints or exceeding the process envelope.
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
The solution provides stable and precise measurements across wide web widths by maintaining registration and alignment, reducing mechanical interference, and allowing for accurate thickness and basis weight determination with improved precision and accuracy, even for thin materials and layered composites.
Implementation Method 1
The sensor may be a non-contact displacement sensor, such as parallel plate capacitive sensors
Implementation Method 2
parallel plate capacitive sensors
Implementation Method 3
x-ray tube and detector sensors
Implementation Method 4
beta source and beta detector sensors
Implementation Method 5
gamma source and gamma detector sensors
Implementation Method 6
pulsed terahertz sources and sensors
Data Source
AI summary
An apparatus for measuring thickness and/or basis weight of a web or film has a frame defining a measurement channel between two opposing frame faces. A first sensor component is on or appended to the first face and a second sensor component is on or appended to the second face of the frame. A series of rollers guide the web or film into the measurement channel in an overlapping relation such that at least two portions of said web reside in said measurement channel for detection by the sensor. The frame may be a C-frame gauge, and the sensor may be two capacitor plates. One sensor component is a source, while the opposing sensor component is sensitive to the source emission. The combined thickness of the portions of the web residing in the measurement channel is determined based upon the degree to which the web or film attenuates the emission.