Capacitive High-Frequency Foreign Body Detection in Fibrous Products
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Solution Overview
Problem
Existing measuring apparatuses for detecting foreign bodies in fibrous products like tobacco and cotton are complex due to their reliance on microwave resonators, which require high precision and elaborate circuitry, limiting their simplicity and effectiveness.
Innovation Solution
A capacitive measuring apparatus using a high-frequency field below the microwave range, with a capacitor instead of a microwave resonator, and a non-resonant circuit design, allowing for a more homogeneous field and reduced circuit complexity, enabling detection of foreign bodies by evaluating deviations in measurable variables such as capacitance and loss factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microwave resonators are used for detecting foreign bodies, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential measurement function from the complex microwave resonator system and implements it using a simple capacitor. By removing the resonator structure and using only a capacitor to generate the high-frequency field, the device achieves foreign body detection capability while dramatically reducing circuit complexity and eliminating the need for elaborate resonant circuitry.
Solution Approach 2:
The patent creates a simplified version of the microwave measurement system by using a capacitor that operates at high frequencies below the microwave range. This copied approach replicates the essential measurement functionality of detecting dielectric property changes caused by foreign bodies, while using a much simpler structural implementation than the original microwave resonator design.
2Measurement precision
If microwave resonators are used for detecting foreign bodies, then measurement precision is improved, but device size increases
Solution Approach 1:
The patent extracts the essential measurement function from the complex microwave resonator system and implements it using a simple capacitor. By removing the resonator structure and using only a capacitor to generate the high-frequency field, the device achieves foreign body detection capability while dramatically reducing circuit complexity and eliminating the need for elaborate resonant circuitry.
3Device complexity
If high-frequency fields below microwave range are used, then device complexity is reduced, but measurement precision may worsen
Solution Approach 1:
The patent changes the frequency parameter from the microwave range to high-frequency fields below the microwave range (but still above 10 kHz). This parameter change allows the use of a simple capacitor instead of a complex resonator, reducing device complexity. The patent demonstrates that this frequency adjustment maintains or even improves measurement precision for foreign body detection in fibrous products, as the lower frequencies provide greater sensitivity for detecting macroscopic conduction differences between product and foreign bodies.
4Device complexity
If capacitor is used instead of microwave resonator, then device complexity is reduced, but field homogeneity may worsen
Solution Approach 1:
The patent applies local quality by designing the capacitor and its surrounding structure to create a homogeneous electric field specifically in the product chamber region where measurement occurs. By carefully designing the local field distribution around the capacitor electrodes and using appropriate shielding structures, the patent achieves uniform field penetration through the fibrous product, ensuring consistent measurement conditions throughout the measurement volume.
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 results in a structurally simple and highly precise detection system capable of identifying foreign bodies with increased sensitivity at lower frequencies, reducing the size and elaborateness of the apparatus while maintaining accurate measurements.
Implementation Method 1
A capacitive measuring device for the detection of foreign bodies in a product, in particular in tobacco, cotton or some other fibrous product, comprises a high frequency generating device for generating a high-frequency wave which is supplied to a circuit device. The circuit device comprises a measuring capacitor through which is passed the product to be measured. The high-frequency wave is supplied to an electrode of the measuring capacitor in order to generate in it a high-frequency field which interacts with the product.
Implementation Method 2
Due to its different dielectric properties, in a certain way a foreign body influences the high-frequency field and therefore the determined measurable variables.
Implementation Method 3
The high-frequency wave emanating from the other electrode of the measuring capacitor and influenced by the product is processed by means of the circuit device in order to determine at least one, preferably two, measurable variables independent of each other and dependent on the amplitude and/or the phase of the high-frequency wave influenced by the product. These are preferably two measurable variables dependent on the capacitance and the loss factor of the measuring capacitor.
Data Source
AI summary
The invention concerns a measuring apparatus for the detection of foreign bodies in a product, in particular in tobacco, cotton or some other fibrous product, having a measuring device, a device for generating an alternating electromagnetic field in the measuring device, which is influenced by a product which is arranged in a measuring volume of the measuring apparatus, a circuit device which includes the measuring device and which is designed to determine at least one suitable measurable variable of the alternating field influenced by the product, and an evaluating device which is designed for detection of the foreign body by suitable evaluation of the measurable variable determined with the circuit device, and is distinguished in that the measuring device is a measuring capacitor and the frequency of the alternating field is in the high-frequency range below the microwave range. The application further concerns a corresponding measuring method.