Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2000-12-13
2002-09-17
Sherry, Michael (Department: 2829)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
Reexamination Certificate
active
06452404
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in methods of and in apparatus for ascertaining one or more characteristics of certain substances, such as tobacco. More particularly, the invention relates to improvements in methods of and in apparatus for ascertaining one or more characteristics (such as the mass per unit length and/or the moisture content) of mass flows of particulate materials, such as fragments of tobacco leaf laminae and/or other smokable substances.
It is already known to ascertain certain characteristics of mass flows of tobacco particles by evaluating the extent of detuning, due to the presence of such substances, of a high-frequency resonator which receives microwaves from a suitable generator and transmits high-frequency signals to a suitable evaluating circuit. The extent of shift of the resonance frequency and damping of such high-frequency signals (in comparison with output signals which are transmitted in the absence of mass flows within the range of the high-frequency resonator) is indicative of the characteristic(s) of the material of the mass flow.
The making of smokers' products, such as plain or filter cigarettes, normally involves a testing of the mass flow of tobacco particles which are to form the rod-like fillers of such products. As a rule, the testing involves a determination of the mass of tobacco per unit length of the mass flow and/or the moisture content of the particles in the mass flow and/or the dielectric constant of tobacco (as used herein, the term “tobacco” is intended to embrace natural, reconstituted and artificial (substitute) tobacco). An accurate determination of the mass per unit length and of the moisture content is particularly important in connection with the making of cigarettes or other rod-shaped smokers' products (hereinafter referred to as cigarettes for short). For example, once the percentages of dry ingredients and moisture in a mass flow of tobacco particles are known, one can accurately determine the overall mass of the tested substance by simple addition of the signals denoting the dry mass and the moisture content. The situation is similar in connection with the processing of certain other substances such as foodstuffs, chemicals, textile materials, paper and many others.
German patent No. 40 04 119 discloses the determination of the moisture content of substances in a cavity resonator which is connected to a microwave generator. The patented apparatus resorts to a calibration curve to ascertain the resonance frequency and the half intensity width of the resonance line.
OBJECTS OF THE INVENTION
An object of the invention is to provide a novel and improved method of rapidly and accurately ascertaining one or more characteristics of various substances, such as fragments of tobacco in a mass flow of tobacco particles in a production line for the making of rod-shaped smokers' products.
Another object of the invention is to provide a method which can be resorted to for rapid and accurate determination of various ingredients (such as dry mass and/or wet mass) in mass flows of particulate materials of the type being utilized in the tobacco processing, textile, paper making, chemical, food processing and other industries.
A further object of the invention is to provide method of ascertaining one or more characteristics of mass flow of filter material for tobacco smoke.
An additional object of the invention is to provide method of rapidly and accurately ascertaining one or more characteristics (such as the percentages of solid and liquid ingredients, the total mass and/or the dielectric constant) of a rapidly advancing stream or flow of tobacco or filter material in a cigarette making machine.
Still another object of the invention is to provide a method of in line determination of one or more characteristics of smokable materials, filter materials for tobacco smoke and/or other materials which are being conveyed in the form of mass flows or streams or rods or fillers in various plants of the tobacco processing industry.
A further object of the invention is to provide a novel and improved apparatus for the practice of the above outlined method.
Another object of the invention is to provide a machine or production line which embodies one or more apparatus for the practice of the above outlined method.
An additional object of the invention is to provide the apparatus with novel and improved means for transmitting signals to a resonator arrangement of the above outlined apparatus.
Still another object of the invention is to provide the apparatus with novel and improved means for processing signals being transmitted by the resonator arrangement of the above outlined apparatus.
A further object of the invention is to provide an apparatus which can be utilized with advantage in modern high-speed production lines for the mass-manufacture of plain or filter cigarettes, cigars, cigarillos, cheroots and/or other rod-shaped products of the tobacco processing industry.
Another object of the invention is to provide an apparatus which can be designed to accurately and rapidly ascertain one or more characteristics various substances, such as the dry mass, the moisture content, the total mass and/or the dielectric constant of tobacco particles or filter material for tobacco smoke, in cigarette makers, filter rod makers or other types of production lines.
SUMMARY OF THE INVENTION
One feature of the present invention resides in the provision of a method of ascertaining at least one characteristic of a substance by resorting to a high-frequency resonator arrangement which is detuned in the presence of the substance. The method comprises the steps of supplying or transmitting to an input of the resonator arrangement microwaves having at least two different frequencies whereby an output of the resonator arrangement respectively furnishes or transmits first and second curves of high-frequency output signals in the presence and absence of a substance at the resonator arrangement. Such curves have different amplitudes, and the method further comprises the step of evaluating the output signals including comparing the curves to ascertain shifts of resonance frequencies of the output signals due to the presence of a substance at the resonator arrangement and comparing the amplitudes of the curves to ascertain damping of output signals due to the presence of a substance at the resonator arrangement.
The supplying step can include continuously transmitting to the input of the resonator arrangement microwaves having at least two different frequencies.
The method can further comprise the step of periodically varying the frequencies of microwaves which are being transmitted to the input of the resonator arrangement. This varying step can include repeatedly shifting between higher and lower frequency values. Such varying step can also include repeatedly and continuously wobbling between higher-frequency and lower-frequency values. The frequencies of the microwaves can be allocated to a sloping flank of a curve of high-frequency output signals. The wobbling step can involve substantially sinusoidally wobbling the frequencies of the microwaves between threshold values with relatively small frequency changes or differences. The output signals can have d-c fractions and substantially sinusoidally varying a-c fractions. The evaluating step of such method can comprise transmitting the d-c fractions and the a-c fractions to discrete calculating or computing stages, polynomially computing the fractions in the respective stages with constants to thus generate partial signals, and adding or summing the partial signals. Such evaluating step can further comprise ascertaining the constants by parameterization on the basis of reference values of the substance; such reference values can include—as a function of the at least one characteristic to be ascertained in accordance with the novel method—at least one of the density/mass, moisture content and dielectric constant of the substance being tested.
The aforementioned threshold
Moeller Henning
Noack Andreas
Tobias Joerg
Hauni Maschinenbau AG
Kinberg Robert
Nguyen Jimmy
Sherry Michael
Venable
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