Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2002-03-14
2004-06-08
Deb, Anjan K. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S634000, C324S639000
Reexamination Certificate
active
06747460
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
Priority is claimed herein with respect to German Patent Application Serial Nos. 101 12 499.6 filed on Mar. 15, 2001 and 101 57 266.2 filed on Nov. 22, 2001, the subject matter of which, along with the subject matter of each and every U.S. and foreign patent document mentioned herein, is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a resonator device, in particular a microwave resonator device, for testing a material quantity and especially a material flow in the tobacco-processing industry for the existence of at least one foreign substance and/or for detecting the weight, density and/or humidity level of the material or material flow. The resonator device is provided with at least one resonator housing and at least one opening in each resonator housing for the material or material flow to pass through.
The invention furthermore relates to a corresponding measuring device, especially a microwave measuring device, as well as a measuring system, in particular a microwave measuring system, for testing a material quantity and especially a material flow in the tobacco-processing industry for the existence of at least one foreign substance and/or for detecting the weight, density and/or humidity level of the material. Such a measuring device comprises at least one resonator housing, inside of which an electromagnetic field can be generated and which has at least one through opening for the material.
Finally, the invention relates to a method for testing a material for the existence of at least one foreign substance and/or for detecting the weight, density and/or humidity level of the material.
A corresponding resonator device or resonator housing for microwaves is known from German Patent No. 198 54 550 A1 commonly owned by the present assignee. This document discloses a resonator housing for the tobacco-processing industry, through which a rope of tobacco is moved and is subjected to microwaves for the purpose of detecting the weight and/or humidity level of the rope material. The purpose of this resonator housing is to improve the measuring accuracy and, if necessary, the measuring sensitivity when detecting the weight and/or humidity level of filler materials for ropes in the tobacco-processing industry. According to German Patent No. 198 54 550 A1, this is achieved by producing the housing at least in part from a material with a low expansion coefficient, so that with a corresponding fluctuation in the temperature, the housing essentially retains the same shape. It also improves the measuring accuracy if the resonator housing temperature is controlled to be at a constant value. Finally, it is advantageous according to the aforementioned reference if the interior housing walls are at least partially coated with a corrosion-resistant metal or consist of such a metal. The measuring accuracy for detecting the weight and/or humidity level for the aforementioned materials can be improved considerably in this way.
German Patent No. 101 00 664.0 also commonly owned by the present assignee, furthermore discloses a method for testing a production material or a material quantity primarily containing a production material, wherein the material is tested for the existence of a foreign substance. A microwave field is generated for this, the material is moved into the effective range of the microwave field and its influence on the microwave field is analyzed, wherein the actual values of a first and a second characteristic variable of the microwave field are measured simultaneously. A reliable value range is specified for these actual values and these are checked to determine whether the actual values are in the reliable range. A signal is generated if the actual values are outside of the reliable value range. For the purpose of this invention, the variable for a microwave field includes real variables of the generated microwave field, such as amplitude and phase, as well as variables of the components for guiding a microwave field, e.g. the resonance frequency and the band width of a resonator in which the microwave field propagates.
With the known measuring method, the goods to be measured are moved through the field of a resonator, wherein the dielectric properties of the goods to be measured change the field. By measuring the change in the resonance properties or the field, it is possible to determine the weight, density and humidity level as well as to detect foreign substances. However, it is difficult to detect very small foreign substances or to achieve a relatively exact local resolution. In particular the position of the foreign substance relative to the field orientation determines the measuring accuracy.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a resonator device, a measuring device and a measuring system, which increase the sensitivity of a method for determining whether a material flow contains a foreign substance and/or for detecting the weight, density and/or humidity level of the material flow or the material quantity.
Furthermore, it is an object of the present invention to increase the sensitivity of such a method and, in addition, provide means and a method for improving the accuracy and the local resolution of respective measurements.
The above and other objects are solved with a resonator device, in particular a microwave resonator for testing a material, in particular a material flow, in the tobacco-processing industry for the existence of at least one foreign substance and/or for detecting the weight, density and/or humidity level of the material or the material flow. The resonator device comprises a housing provided with an opening for the material quantity or the material flow to pass through, wherein the material can be transferred at least in part to a testing area, located in particular inside the resonator. At least one element that increases the energy density of electromagnetic waves is provided, wherein the energy density can be increased at least in a portion of the testing area.
As a result of this measure, a kind of bundling of the electromagnetic waves is possible in the testing area, which results in an increased flow of the respective waves, in particular microwaves, through the material to be checked or the region of the material flow to be checked. As a result, the sensitivity when measuring the weight, density and/or humidity level of the material flow and/or when testing for the existence of a foreign substance is increased, without the necessity of coupling additional energy into the resonator device. For the purpose of this invention, increasing or raising the energy density of electromagnetic waves in particular also means that these waves are bundled, focused, narrowed down or compacted. The electromagnetic waves preferably are microwaves. A material is advantageously tested with the resonator device according to the invention. The material advantageously is a material flow. For the purpose of this invention, the term testing region also encompasses the term measuring region.
The element preferably comprises a line resonator with at least one end face functioning as electrode. By using a line resonator, the waves coupled into the resonator can be bundled easily and effectively, wherein the waves or the respective field in particular exit the end face in the form of a beam.
It is advantageous if a coupling-in antenna and a coupling-out antenna are provided, which are arranged symmetrically inside the resonator. The antennas are furthermore arranged near a spot on the line resonator, where the field component that induces the coupling has a high amplitude, preferably a maximum.
A particularly good coupling of the waves coupled in and out of the element occurs if the element is preferably arranged inside a resonator cavity, at a distance to the walls delimiting the cavity.
A particularly effective method for testing the material flow is possible if the at least one end face is arranged near the material flow or the material quantity
Knöchel Reinhard
Möller Henning
Taute Wolfgang
Tobias Jörg
Anderson Chad C.
Deb Anjan K.
Hauni Maschinenbau AG
Kinberg Robert
Venable LLP
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