Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2002-01-03
2004-07-27
Le, N. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S640000, C131S109200, C131S905000
Reexamination Certificate
active
06768317
ABSTRACT:
CROSS-REFERENCE TO RELATED CASES
The present application claims the priority of the commonly owned copending German patent application Serial No. 101 00 664.0 filed Jan. 9, 2001. The disclosure of the above-referenced German patent application, as well as that of each US and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to improvements in methods of and in apparatus for testing materials for the presence or absence of impurities and/or other foreign matter, for example, to methods of and to apparatus for detecting the presence (if any) of one or more second (foreign) materials or substances in a body or mass which consists primarily of a first (particulate) material. More particularly, the present invention relates to improvements in methods of and in apparatus for monitoring or testing or examining a mass normally consisting of a first material for the presence or absence of one or more second materials (hereinafter often called impurities for short) by resorting to a microwave field which is influenced by the impurities contained in the first material when the impurities-containing first material is introduced into the range of the microwave field.
An example of a first material which is or which might be likely to contain one or more impurities (such as metallic or plastic particles) is tobacco, e.g., the so-called rod-like filler of a running continuous cigarette rod or the fillers of discrete cigarettes running endwise or sideways in a cigarette making and/or processing machine. It is important to detect the presence of impurities in tobacco which is processed in modern high-speed machines or apparatus designed to turn out and/or to automatically process huge quantities of smokers' products per unit of time. Certain machines or apparatus of such character are set up to subject a running mass or flow or a plurality of discrete masses or flows of comminuted natural, artificial and/or reconstituted tobacco to a series of successive treatments by resorting to belt conveyors, chain conveyors or analogous transporting means which advance tobacco between various stations or units, storage facilities and/or others.
It is inevitable or at least highly likely that the treatment of tobacco and/or of tobacco-containing products or similar products or commodities of the tobacco processing industry (e.g., filter material for tobacco smoke which is processed in filter rod making, filter cigarette making and similar units) results in or causes the introduction of impurities into tobacco, filter material and/or other primary or first materials. The presence of metallic particles, plastic particles and/or other impurities in plain or filter cigarettes and/or other finished smokers' products can adversely influence the appearance, the taste, the rate of combustion and/or other characteristics of such products. Therefore, the relevant industries are continuously seeking to arrive at methods and apparatus for reliably detecting impurities in smokers' products, and especially at improved methods and apparatus which can be put to use in modern high-speed machines (such as cigarette or filter cigarette making machines) that are capable of detecting impurities and/or of preventing introduction of impurities without necessitating a deceleration of such machines and without adversely affecting the appearance, the taste, the quality and/or other desirable characteristics or parameters of the products. The same holds true for the methods of and for the apparatus for mass-producing numerous other commodities, e.g., the aforementioned filter rods for tobacco smoke, filter rod sections and/or others.
Conventional undertakings to detect impurities in a primary or first material include numerous optical processes one step of which involves advancing the primary material along a path wherein the material is converted into a thin (single-stratum) layer. The exposed surface of the layer is photographed by one or more cameras and the thus obtained pictures are processed for the purpose of detecting and pinpointing foreign bodies (impurities) preparatory to their removal or expulsion from the layer. A drawback of such processes is that the equipment which is necessary for their practice is bulky and that such equipment can be put to use only during initial processing, e.g., during treatment of tobacco or filter material prior to entry into a cigarette rod making, filter rod making or an analogous machine. Consequently, the just described processes and apparatus cannot be resorted to for the detection of impurities which enter the primary material in a cigarette making, filter rod making or analogous machine, namely subsequent to confinement of the fillers of cigarettes, filter mouthpieces or the like in tubular wrappers consisting of or containing cigarette paper, artificial cork, tipping paper or the like.
In order to overcome the shortcomings of processes which are effective only during preliminary treatment of primary material (e.g., during transport of tobacco or filter material for tobacco smoke into a cigarette rod making or filter rod making machine), many machines of such character embody or are combined or associated with (a) suitable sifting devices which are capable of removing from the flow (stream) of tobacco or from the flow (tow) of filter material for tobacco smoke entering a cigarette maker or a filter rod maker certain heavier particles (such as tobacco ribs) and/or (b) with metal detectors (e.g., magnets) capable of detecting and/or detecting and segregating defective articles such as plain or filter cigarettes or filter rod sections. A drawback of the just discussed undertakings is that they can detect and/or remove only certain types of impurities so that, unless combined with sifting or the like, each such undertaking can ensure only the detection and segregation of a relatively low percentage of all impurities.
Certain additional presently known processes and apparatus for the detection of impurities rely upon the utilization of microwaves which are resorted to for the monitoring of specific parameters (such as the density and/or the moisture content) of finished or semifinished smokers' products, for example, a continuous cigarette rod and/or discrete plain or filter cigarettes. An advantage of such undertakings is that they can furnish information with a very high degree of accuracy. Their effectiveness is attributable to the fact that the primary material (such as tobacco) is a satisfactory dielectric and highly hygroscopic so that it can contain a relatively high percentage of water (e.g., between about 10 and 20 percent by weight). In addition, water is also a highly satisfactory dielectric substance and, due to pronounced mobility of the molecular dipoles, exhibits a high loss factor at microwave frequencies. Such characteristics enable tobacco to exert a pronounced influence upon a microwave field, and this influence renders it possible to adequately distinguish between water and dry tobacco. Reference may be had to the disclosure in U.S. Pat. No. 4,707,652 granted Nov. 17, 1987 to Lowitz for “IMPURITY DETECTOR MEASURING PARALLEL POLARIZED SCATTERED ELECTROMAGNETIC RADIATION”. The method which is disclosed in this patent involves a determination of abnormalities in spatial scattering of a microwave field by a tobacco sample to thus detect the presence or absence of impurities, such as metallic or plastic substances. The patented process is suitable for experimental practice in a laboratory, and its operation is satisfactory as long as the relative speed between the monitoring equipment and a sample is relatively low, i.e., such process cannot be resorted to in a high-speed machine, e.g., in a cigarette maker which turns out cigarettes in the range of up to 20,000 per minute.
OBJECTS OF THE INVENTION
An object of the invention is to provide a novel and improved method of at least detecting but preferably of detecting
Möller Henning
Tobias Jorg
Anderson Chad C.
Dole Timothy J.
Hauni Maschinenbau AG
Kinberg Robert
Le N.
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