US-12625066-B2 - Detecting a mixture ratio of two components of a textile fiber structure

US12625066B2US 12625066 B2US12625066 B2US 12625066B2US-12625066-B2

Abstract

A device for detecting a mixture ratio of two components of a textile fabric contains a radiation source for transmitting electromagnetic radiation in a spectral band in the direction of the textile fiber structure, a radiation sensor for receiving at least a part of the electromagnetic radiation, and a spectral filter with spectral properties in the spectral band for filtering at least one part of the electromagnetic radiation. The transmittance of the spectral filter in the spectral band has at least one local maximum and at least one local minimum. The spectral properties of the spectral filter in the spectral band are adapted to the spectral properties of the radiation source and each of the two components such that a radiation intensity received by the radiation sensor is a monotonous function of the mixture ratio of the two components. The device is simple in design and allows the use of spatially resolving imaging radiation sensors.

Inventors

Rainer Jacob

Assignees

USTER TECHNOLOGIES AG

Dates

Publication Date: 20260512
Application Date: 20220315
Priority Date: 20210326

Claims (16)

1 . A device for detecting a mixture ratio of two components of a textile fiber structure, containing: a radiation source for transmitting electromagnetic radiation in a spectral band in a direction of the textile fiber structure for interaction with the textile fiber structure, a radiation sensor for receiving at least one part of the electromagnetic radiation after interaction with the textile fiber structure, and a spectral filter having spectral properties in the spectral band for filtering at least a part of the electromagnetic radiation before or after interaction with the textile fiber structure, wherein a transmittance or a reflectance of the spectral filter in the spectral band has at least one local maximum and at least one local minimum, and the spectral properties of the spectral filter in the spectral band are adapted to the spectral properties of the radiation source and each of the two components such that a radiation intensity received by the radiation sensor is a monotonous function of the mixture ratio of the two components.
2 . The device according to claim 1 , wherein the at least one local maximum lies at a wavelength or wavelengths of the electromagnetic radiation at which an absolute value of a difference of an absorptance, a transmittance, or a reflectance of the two components has a local maximum.
3 . The device according to claim 1 , wherein a transmittance or a reflectance of the spectral filter in the spectral band has at least two local maxima and local minima each.
4 . The device according to claim 1 , wherein the spectral filter is designed as a reflection filter or as a transmission filter.
5 . The device according to claim 1 , wherein the spectral filter is designed as an interference filter.
6 . The device according to claim 1 , wherein the spectral filter is integrated into the radiation sensor.
7 . The device according to claim 1 , wherein the spectral band is in a wavelength range between 300 nm and 2200 nm.
8 . The device according to claim 1 , wherein the spectral band has a width between 200 nm and 500 nm.
9 . The device according to claim 1 , wherein the radiation sensor is spatially resolving and/or time resolving.
10 . The device according to claim 9 , wherein the radiation sensor is formed either as a digital camera with a two-dimensional image converter or as a one-dimensional line sensor.
11 . The device according to claim 1 , wherein the spectral band is in a wavelength range of between 700 nm and 1900 nm.
12 . A method for detecting a mixture ratio of two components of a textile fiber structure, wherein: electromagnetic radiation in a spectral band is transmitted from a radiation source in a direction of the textile fiber structure, at least a part of the electromagnetic radiation interacts with the textile fiber structure, at least a part of the electromagnetic radiation is received by a radiation sensor after interacting with the textile fiber structure, and at least a part of the electromagnetic radiation is filtered by a spectral filter with spectral properties in the spectral band before or after interacting with the textile fiber structure, wherein, the spectral filter is selected such that, a transmittance or a reflectance in the spectral band has at least one local maximum and at least one local minimum, and its spectral properties in the spectral band are adapted to the spectral properties of the radiation source and each of the two components in the textile fiber structure such that a radiation intensity received by the radiation sensor is a monotonous function of the mixture ratio of the two components.
13 . The method according to claim 12 , wherein the spectral band is in a wavelength range between 300 nm and 2200 nm.
14 . The method according to claim 12 , wherein the spectral band has a width between 200 nm and 500 nm.
15 . The method according to claim 12 , wherein one of the two components is a base material of which a predominant part of the textile fiber structure consists, and the other of the two components is a foreign material whose proportion in the textile fiber structure is determined.
16 . The method according to claim 12 , wherein the spectral band is in a wavelength range of between 700 nm and 1900 nm.

Description

FIELD OF THE INVENTION The present invention is in the field of quality monitoring in the textile industry. It relates to a device and a method for detecting a mixture ratio of two components of a textile fiber structure, according to the independent claims. A preferred application is the detection of foreign materials in a textile fiber structure such as fiber flocks, fiber web, sliver, roving, yarn, woven fabric, knitted fabric, or nonwoven. DESCRIPTION OF THE PRIOR ART Foreign materials in the yarn represent one of the major problems of today's spinning mills. These are materials that differ from the base material of the yarn fibers, e.g. cotton fibers. They can be of various origins, such as residues of transport packaging (plastic packaging, cords), civilization impurities (soot parts, plastic bags) or residues of living beings (human or animal hair, plant stalks). Foreign materials cause thread breakage during spinning and weaving, take dye in a different way than the base material and affect the appearance of the final textile product. They significantly reduce the value of the final product. An overview of fabric defects caused by foreign materials and recommendations to reduce them is given in paragraph 3.8 of the USTER® NEWS BULLETIN NO. 47 “The origins of fabric defects—and ways to reduce them”, Uster Technologies AG, March 2010. Foreign materials can be detected and, if necessary, rejected at various stages of the yarn manufacturing process. The blowroom process is part of the yarn manufacturing process and is upstream of the carding process. The aim is to prepare the raw material so that it can be fed to the carding process in as constant a quality as possible and free of impurities. It comprises the opening of the raw material, the feeding of the same into the processing operation, and the mixing and coarse cleaning of the fed material. Depending on the design of the process, individual work steps can be run through several times or even omitted. At this stage of the process, the material is in the form of fiber flocks (for example, in the case of cotton and wool) or shreds (in the case of synthetic fiber material). The material is transported by an air stream that connects the various units in the blowroom process. The spinning process is another part of the yarn manufacturing process and is indirectly or directly downstream of the carding process. In this process, the yarn as the end product is spun from a sliver, e.g., the intermediate product of a carding machine, or a roving. In the process, the roving or sliver is transformed into its final form, the yarn, by drawing and twisting. During spinning, the yarn is wound onto spindles. Subsequently, the spindles are rewound onto large bobbins. The material is transported in the form of spindles and bobbins. The purification of foreign materials can basically be divided into the following three steps: 1) Detection of the foreign material;2) Spatial/temporal localization of the foreign material within the test material; and3) Ejection of the foreign material. In the blowroom process, foreign material cleaning can be carried out manually before the raw material is fed to the automatic converting process, or cleaning can be carried out automatically by appropriate equipment within the blowroom process. Nowadays, automatic cleaning is common. In the case of automatic cleaning, detection and localization are carried out with the aid of detection devices which recognize differences in a certain characteristic within the material flow. The following are mentioned in a non-exhaustive way here: reflection and transmission of electromagnetic radiation or fluorescence. In the simplest applications, optical detection devices are used to mimic the human eye and analyze the color impression of the material stream, detecting corresponding color differences. U.S. Pat. No. 6,452,157 B1 discloses a device for detecting impurities, foreign materials and foreign fibers in textile fiber material. The device has at least two light sources which alternately illuminate the fiber material with different colors. Furthermore, a sensor is provided which receives the colors of the light reflected from the fiber material. However, for the detection of foreign materials that are transparent to visible light or have a similar color to the raw material, more sophisticated detection devices are needed. In this case, the material flow can be analyzed with the help of such electromagnetic radiation which is not perceived by the human eye (ultraviolet or infrared). In this case, the material affiliation is determined on the basis of characteristic signatures (for example, sequence of specific absorption bands) in the reflected or transmitted spectrum of the electromagnetic radiation. The more characteristics (e.g., absorption bands) within the signature are used for discrimination, the more accurate the discrimination of the characteristic signatures becomes. Currently, each chara