Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Reexamination Certificate
2000-08-17
2002-11-05
Le, N. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
C324S636000, C324S640000
Reexamination Certificate
active
06476619
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to density measurements of fibrous materials. In particular, this invention relates to a method and device for determining high-speed, real-time, continuous or stationary, in-line, non-invasive, three dimensional multi-point density deviation and density measurements and calculations of yarn, slivers, or pads of non-homogeneous fibrous material, used in the manufacture of feminine hygiene products (i.e., menstrual tampons, pads, and panty liners), as an example, and other fiber based products.
The manufacture of menstrual tampon products is based on the processing of yarn, slivers, or pads of non-homogeneous fibrous material, consisting of some combination of cotton and synthetic and/or cellulosic fibers. Fiber density and moisture content typically vary during the manufacturing process, primarily due to variation in fiber composition. Combining and controlling the proper relative amounts of cotton and synthetic and/or cellulosic fibers in a given tampon manufacturing production line can be accomplished by incorporating high-speed accurate measurement and control of in-line fiber density, moisture content, and temperature.
The main component of tampons is cotton, with synthetic (e.g., viscose rayon, rayon polyacrylates, polyester) and/or cellulosic (e.g., carboxymethol-cellulose) fibers mixed with the cotton to substantially increase the absorbency and anti-wicking properties of tampons. Since the late 1980's, it has been established through widespread investigation and research, court proceedings (e.g., United States District Court For The District Of Kansas, Case No. 94-1195-FGT), FDA reports and guidelines (e.g., Draft Guidance For The Content Of Pre-market Notifications For Menstrual Tampons, Obstetrics-Gynecology Devices Branch, Office Of Device Evaluation, Center For Devices And Radiological Health, May 25, 1995), that synthetic fibers in tampons are associated with Toxic Shock Syndrome (TSS) and infection in menstrual women. In the case of TSS, the presence of synthetic fibers in tampons has been determined to cause an increase in the production of toxic chemicals in the woman's body. In the case of infection, the presence of synthetic fibers in tampons inhibits the growth or existence of vaginal flora, due to excessive absorbency of vaginal moisture, necessary for proper vaginal health. Additionally, there are reports that synthetic fibers themselves contain toxins (e.g., “The Health Risks of Dioxin”, an FDA scientist's report referenced by U.S. congressman Rep. Ted Weiss, at a hearing of the Human and Intergovernmental Relations Subcommittee, Jun. 10, 1992). At that hearing, the FDA concluded that there was dioxin in rayon, and stated that if they (the FDA) did have a problem with medical devices, “menstrual products would be the greatest simply because of the mass of the material and the duration of exposure”. Thus, the potential of tampons causing TSS or infection is directly related to the synthetic fiber content, which in turn, is related to the overall tampon raw material fiber density and moisture content. From this background and information, it is apparent that accurate measure and control of density and moisture content during the manufacture of tampons is important not only from a manufacturing quality control viewpoint, but, also, from a health issue viewpoint.
In the manufacture of products containing fibrous yarn, sliver, or pad raw material, it is desirable to use the fiber density as a primary control parameter, especially in real time, in-line, and continuous mode of operation, in order to maintain product quality assurance (i.e., product composition and performance reproducibility). For a given composition of yarn, sliver, or pad material, fiber density is dependent on its moisture content, and to a lesser extent, dependent upon its temperature. Real time, in-line quality control of the fiber content, of finished feminine hygiene products, for example, is best achieved by measuring and calculating density and moisture deviations and controlling the density and moisture content of the fibrous raw material at both upstream and downstream stages of the manufacturing process.
Prior art devices and methods for measuring fiber density and moisture content are primarily mechanically based, suited for stationary, off-line, and invasive or direct contact operation and analysis of bulk quantities of materials with relatively high densities. Techniques utilizing radiation have been used for density and moisture measurements. Infra-red techniques can be used for moisture determination, but these require direct contact with the material, and are affected by the presence of industrial dust and the focal plane immediately around the sample; Beta rays have been used for density determination, but here there is a health hazard limitation in its application at manufacturing sites. Microwave and other electrical devices and methods for measuring density deviations and density of fibrous materials via moisture and temperature measurements discussed by Kraszewski, A. W. (Microwave Aquametry-Needs and Perspectives, IEEE Transactions On Microwave Theory And Techniques, vol. 39, no. 5, May 1991), provides background and discusses the development of microwave equipment for purposes of electrical monitoring of moisture content in materials. Included there are useful basic definitions, principles, and equations pertaining to microwave analysis of moisture content in materials. At specified material temperature, changes in attenuation and phase-shifts of transmitted microwaves are used for calculating material moisture and density values, respectively.
U.S. patent application Ser. No. 08/974,983, and now U.S. Pat. No. 6,025,724 and Ser. No. 08/777,872, and now U.S. Pat. No. 5,845,529 describe microwave based devices and methods for determining the moisture content of packaged, and non-packaged material, respectively, utilizing various antenna configurations as the source and receiver of transmitted microwave radiation. The earlier of this pair of related patent applications, U.S. patent application Ser. No. 08/777,872, describes moisture content determination of a given module of material (e.g., cotton, paper, processed wood, tea, synthetic fibers). The moisture measuring equipment is aimed at monitoring upstream incoming raw fibrous material, i.e., prior to fibrous material entering the CARD (i.e., fiber separating and processing) machine, and represents a ‘coarse’ monitoring and analysis of moisture content of upstream incoming fibrous material. As such, the invention is essentially limited to measurement of relatively large (bulk) quantities of minimally processed, high density fibrous material (e.g., typically, 10-15 kilograms per cubic meter), and not highly processed, low density fibrous material (e.g., typically, 4-12 grams per meter, linear density) composed of loose fibers, such as yarn, slivers, or pads (e.g., for tampon production). Moisture content is determined as a function of changes in signal attenuation (amplitude). Compensation of the phase shift for moisture and temperature change is not shown, and there is no discussion pertaining to density deviation measurement or calculation.
U.S. patent application Ser. No. 08/974,983, builds on U.S. patent application Ser. No. 08/777,872, in that compensation for temperature changes of the material, and a method for measurement and calculation of density deviations of indicated material, are included in the invention. A similar, microwave based, dual antenna device is used; phase-shifts and signal attenuation measurements, are used for calculating density and moisture content, respectively. An algorithm was developed to process and maintain the numerical information and data. This invention, too, is essentially limited to measurements of relatively large (bulk) quantities of minimally processed, high density material, and not highly processed, small density fibrous material composed of loose fibers, such as yarn, slivers, or pads. Moreove
Buzik Leonid M.
Greenwald Alexander
Moshe Danny S.
Benson Walter
G.E. Ehrlich Ltd.
Le N.
Malcam Ltd.
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