Apparatus and methods for measurement and classification of generalized neplike entities in fiber samples

Abstract: Method and Apparatus for measuring and classifying individual neplike entities in a textile fiber sample is disclosed. The apparatus includes a fiber sample processor which takes a supply of fiber samples, separates and individualizes the individual entities of the fiber sample and provides the individualized entities to an airflow. The airflow directs the entities through a sensor volume which utilizes electro optical sensors to generate characteristic signals corresponding to the entity passing through the sensor volume. These signals are then analyzed to determine if the entity passing through the sensing volume was a nep and further classify neps by their type. Thus, a neplike entity could be classified as a either a polyester nep, a fiber nep or a seed coat fragment and further may be classified as a mature entity or an immature entity.

Description: Field of Invention This invention relates to the field of the measurement and classification of individual textile entities in a fiber sample and particularly to an apparatus and methods for the measurement and classification of neplike entities in a fiber sample, particularly in a high speed testing environment. Cross Reference to Related Applications This application is a continuation-in-part of U.S. Patent 5,469,253 entitled "Apparatus and Method for Testing Multiple Characteristics of Single Textile Sample With Automatic Feed" and US-5,270,787 (=WO91/14169) entitled "Electro-Optical Methods and Apparatus for High Speed Multivariate Measurement of Individual Entities in Fiber or Other Samples" whose disclosure is incorporated herein by reference. Background of Invention The predecessor instrument to the present invention is manufactured by Zellweger Uster, Inc. and is known as AFIS (Automated Fibre Inspection System). This instrument separated fibers and neps into one airstream and trash into another airstream using the device disclosed in U.S. Patent No. 4,512,060. Trash is defined as foreign matter having size greater than about 50 µm. Sometimes this foreign matter is called dust and trash but we shall use the designation trash here for simplicity. In this predecessor, AFIS, it was necessary to test three sets of replicate samples of textile material separately to determine information about fibers, neps and trash. One test and one separate sample of textile material was necessary for each type of entity for each replicate. Although this AFIS provided the best data available at the time for automated and fast textile testing instruments, there was a need for better data and increased speed. An improved sensor was discovered and is disclosed in above cited US-7 5270 787 (=WO 91/14169), which constitutes the most relevant prior art in this case, and the instrument incorporating the improved sensor, also known as AFIS, is manufactured by Zellweger Uster Inc. For clarity and consistency with the references, the first instrument is called AFIS-0 and the instrument with the improved sensor is called AFIS-1. The present invention is a further improvement in AFIS-1 and is directed primarily to testing rate considerations. It was first discovered that the improved sensor of AFIS-1 produced data that would enable substantially simultaneous measurement of multiple data from the same sample of textile material. By "substantially simultaneous" it is meant that nep data, fiber data and trash data are obtained by testing a single sample of textile material and detecting and measuring substantially all of the neps and trash and detecting and measuring a representative sample of the fibers. Thus, this improvement eliminates the need to run three separate tests on typically 3-5 replicates of three separate samples to obtain data for neps, trash and fiber. Also, it was discovered that such data could be obtained using only one sensor, if desired. The testing speed improvements discussed above are made possible by a new analyzer circuit, which is a hybrid analog and digital circuit in the preferred embodiment. Speed of operation is increased by a factor of three in the present invention as compared to AFIS-1 or AFIS-0. With the advent of high speed handling, the need for accurate and high speed characterization of entities in a test sample is necessary. Although the basic count and size information of trash and individual fibers is sometimes sufficient, more detailed information about neps and trash is required. Neps in staple textiles are broadly defined to be small clumps or entanglements of fiber. They are one of the three main constituents of staple fiber. However, neps may be broken down into three further categories; mechanically generated neps, seed coat neps, and shiny (or immature) neps. A mechanically generated nep is created during the opening, ginning, and carding of the cotton and can range from 0.1mm to 5mm in diameter. They are tightly knotted cotton or man-made fibers consisting of a tangled core and a long fiber tail that cannot be opened during processing. Seed coat neps or seed coat fragments are composed of a collection of fibers that remain attached to the shell of the cotton seed. When viewed in visible light, they are small tufts of fibers attached to a dark central core. A shiny nep or dye resistant nep is a collection of very immature or dead cotton fibers. These are formed on the cotton seed when a part or all of the cotton seed undergoes stress that stops the maturation process of the fibers. The resulting fibers are very thin and weak with very little lateral stiffness and can easily form tight clumps of closely packed, parallel fibers. These very immature fibers cannot absorb dyestuffs properly and result in white specks and discolorations in finished fabric. These shiny neps may or may not be attached to the seed coat. With these descriptions in mind, it is easy to understand the importance of classifying neps into these categories. Mechanically generated neps are indicative of the aggressiveness of the processing machinery and, therefore, an accurate count of these particles is used to fine tune or even overhaul processing machinery. The distinction between polyester, the most common man-made fiber, and cotton neps is important as they are often processed separately and combined in sliver form at a drawing frame. Seed coat fragments originate from the cotton plant and their numbers are influenced by the method of ginning and cleaning and the species of cotton. Seed coat fragments are particularly troublesome in that they are a major source of yarn defects. The number of these particles per unit weight provide useful information to the grower about seed-to-fiber tenacity, to the ginner about the aggressiveness of the seed removal process and to the processor about the quality of the raw material. Shiny nep counts predict the dyeability of the processed and spun cotton. Specifically, the number of these shiny neps per gram predicts the quality of the appearance of the finished and dyed fabric allowing the quality conscious mill operator to direct the highest quality material to the most demanding applications. The quantity and quality of trash in a sample of fiber is important to textile processors for reasons analogous to those discussed above. Trash occurs in cotton primarily as a result of mechanical picking and such trash may be classified as fibrous or non-fibrous and may be further sub-classified as fibrous bark, fibrous grass or leaf, flake grass or leaf, thick trash (seed coat fragments and some bark), dust or fiber fragments. The classification of trash in a sample will reveal problems in prior processing, will facilitate corrective processing, and will help predict the quality of the end-product (usually yarn) produced from the fiber. It is therefore one object of the present invention to provide a method and appartus for measuring characteristics of entities in a sample of textile material and permitting to distinguish the entities such as fibres, several types of neps, and for receiving more detailed information about the raw materials for the cotton grower, the ginner, the yarn or thread spinner and the fabric mill. Summary of the invention A preferred embodiment of the present invention addresses the concerns outlined above. In a preferred embodiment, there is provided an apparatus for measuring characteristics of entities in a sample of textile material with the sample containing at least neps which utilizes a supplier to provide the textile sample. The textile material could be supplied by an individual separating the material into samples or by an automated sampler. From the supplier the textile sample is provided to a processor which separates the entities and individualizes them to provide single entities to be tested. The individualized entities are then provided at the output of the processor into a transport airstream. The transport airstream then presents the individualized entities to a sensor which senses at least one characteristic of the individualized entities and produces characteristic signals which correspond to the sensed characteristic. In a further embodiment of the present invention, the sensor incorporates a first light source which produces and directs light along a first light path to impinge on the entities to be sensed in the sensor. A second light source produces and directs light along a second path which also impinges upon the entities in the sensor. An extinction sensor is placed in the first light path and oriented such that the entities to be sensed pass between the first light source and the extinction sensor. The extinction sensor senses light extinction and produces an output corresponding to the light extinction caused by the entity in the sensor and produces an extinction signal corresponding sensed extinction. The sensor further incorporates a forward scatter sensor which receives forward scattered light scattered by an entity passing through the first and second light paths. The forward scatter sensor produces a forward scatter signal corresponding to the sensed forward scattered light from the entity. In this embodiment, the analyzer includes a sub-analyzer which compares the light extinction signal to the forward scatter signal and determines whether the signals correspond to a nep and can further classify the signals as corresponding to one of several different types of neps. In a further embodiment of the present invention, the first light source is an infrared light source and the second light source is an ultraviolet light source. In this embodiment, the forward scatter sensor also has several components. A first forward scatter sensor is positioned and adapted to be responsive to forward scattered light from the first infrared light source. A second sensor is positioned to receive a portion of the light scattered by the entity from the ultraviolet light source and is adapted to be responsive to blue light emitted as a result of any fluorescence of the entity passing through the ultraviolet light beam. In this embodiment, the sub-analyzer analyzes the light extinction signal, the light scatter signal and the fluorescent signal and, based at least in part on these signals, determines whether a particular signal corresponds to a nep and further classifies the signal segments which correspond to different types of neps. An additional embodiment of the present invention is a method for determining the type of an individual neplike entity. First a sensing volume is provided and a ultraviolet light beam is generated and directed through the sensing volume. A fluorescence detector is positioned to one side of the sensing volume so that at least a portion of any light emitted by an object fluorescing as it passes through the ultraviolet light beam will fall on the fluorescence detector. An airflow is generated and directed through the sensing volume so that it passes through the ultraviolet light beam. Entities to be sensed are then introduced into the airflow and a fluorescence signal is generated at the fluorescence detector which corresponds to any fluorescence emitted from the entity. The fluorescence signal is then compared to a threshold, and if the fluorescence signal is greater than the threshold, the entity is classified as a polyester nep. If the fluorescence signal is less than the threshold, the entity is classified as non-polyester. A further embodiment of the present invention provides a method for determining the maturity and type of individual textile entities. A sensing volume is provided and a first light beam is generated and directed through the sensing volume. First and second extinction sensors are positioned to one side of the sensing volume, opposite the first light beam and adjacent one another so that the first light beam falls on the extinction sensors. A forward scatter detector is disposed to one side of the sensing volume such that at least a portion of any light forward scattered by an object passing through the first light beam will fall on the forward scatter detector. The next step in the method is generating and directing an airflow through the sensing volume so that it passes through the first beam of light and between the first beam of light and first and second extinction sensors. An entity to be sensed is then introduced into the airflow and characteristic signals corresponding to characteristics of the entity are generated as the entity passes through the light beam at the first and second extinction detectors and the forward scatter detector. A ratio of a characteristic signal corresponding to the peak value of the signal at the forward scatter detector to the peak value of the signal at one of the first and second extinction detectors is generated and compared to a first threshold. If the ratio is less than or equal to the first threshold, the entity is classified as immature and if the ratio is greater than the first threshold, the entity is classified as mature. A further embodiment of the method includes the additional steps of generating a speed signal corresponding to the speed of the entity from the characteristic signals and comparing the speed to a predetermined second threshold. If the speed is greater than the second threshold, the entity is classified as a nep and if the speed is less than the second threshold, the entity is classified as a seed coat fragment. Thus, with these additional steps, the mature or immature entity may further be determined to be a seed coat fragment or nep and classified accordingly. A further embodiment of this method includes a step of sizing the entity which is accomplished by calculating the core diameter of the entity based on at least one of the characteristic signals and a first constant and calculating the length of the entity based on at least one of the characteristic signals in a second constant. Brief Description of The Drawings The present invention may best be understood by reference to the following Detailed Description of preferred embodiments when considered in conjunction with the Drawings in which: FIGURE 1 is a perspective view of the exterior of a fiber testing apparatus, a preferred embodiment of the present invention; FIGURE 2a, 2b and 2c are illustrations of three classes of neps; FIGURE 3A shows an alternate sensor; FIGURE 3B shows the sensor of FIGURE 3A as it is connected to the data acquisition board; FIGURE 4 are graphs of waveforms produced by various neps passing through the sensor of FIGURE 3; FIGURE 5 is a flow chart of a nep classification program; FIGURE 6 is a pie chart showing the classes of neps; FIGURE 7 is a pie chart showing the classes of trash; FIGURE 8 is an illustration of various types of trash; and FIGURES 9A, 9B and 9C are flow charts of a trash classification program. Detailed Description Referring now to the drawings in which like reference characters designate like or corresponding parts throughout the several views, there is shown in Figure 1 an external view of the textile testing apparatus 10 constituting a preferred embodiment of the present invention. The testing apparatus 10 includes a main housing 12 with an automatic carousel 14 mounted on the top of housing 12 for holding textile material samples. A feed head 16 extends from the carousel 14 for loading textile samples into the testing apparatus 10. The operation of the testing apparatus 10 is under control of a computer 18 which interfaces with the operator through a display 20 and a keyboard 22. In the preferred embodiment, the testing apparatus 10 is used to test textile materials and is particularly designed to measure the characteristics of textile fibers, neps and trash, but the testing apparatus 10 would be equally operable on any entity having size and weight characteristics that are comparable to the aforementioned textile entities. In the above described system, particles were broadly classified as fibers, neps or trash. Below, two variations of the system are described, one which sub-classifies trash and another which sub-classifies neps. These systems variations may be used separately or in combination depending upon the needs of a particular application. Before describing the neps sub-classification program, referring now to FIG. 2, a better understanding of the nature of textile neps may be had. As was previously discussed, neps may generally be broken down into several categories, mechanically generated neps, shiny neps and seed coat fragments. As is shown in FIG.2, seed coat fragments 400 are generally made of a fragment of the cotton seed 402 to which cotton fibers 404 are attached. A mechanically generated nep 406 is generally comprised of a tangled core of fibers 408 along with a less dense tail of trailing fibers 410. Finally, a shiny nep 412 is generally made of a tightly tangled core 414 of immature fibers with a less dense tail of trailing fibers 416. Further, seed coat fragments may be subdivided into mature or immature fragments. Mechanically generated neps may also be subdivided into polyester neps, which fluoresce under ultraviolet light or others which do not. An alternate electro-optical sensor 418 and data acquisition electronics 161 are shown in FIGURE 3A and 3B. The alternate embodiment provides for additional information of neps and trash in order to characterize them further. The alternate electro-optical sensor 418 consists of two radiation sources; an infrared source 420 having a wavelength of about 880 nm and an ultra-violet source 422 having a wavelength of about 370 nm. These sources propagate through the gap 424 between the two opposing nozzles 106 and 110 in the flow cell 104 to form an IR beam 426 and a UV beam 428. The IR source 420 is received by a set of extinction detectors 430, 432 to measure the size and speed of the entity as it passes through the beam 426 as was previously discussed. A second detection system 434, located behind the imaging lens 436, collects the radiation scattered from the entity at angles from about 30 to 50 degrees. This system 434, is comprised of a beam splitter 438 and two detectors 440 and 442. The beam splitter 438 directs about one-half of the radiation to a fluorescence detector 442 which is sensitive to blue visible light (approximately 400 nm - 480 nm). The remaining half of the radiation is directed to an IR detector 440 which is sensitive to the near infrared (approximately 880 nm). The detector 442 responds to the fluorescence (blue light) from the passage of polyester through the UV beam 428. All other common textile materials such as cotton and rayon do not exhibit UV fluorescence to a significant degree. The near infrared detector 440 responds to the 880 nm light scattered by the entity. This IR scattering provides information about the surface characteristics of the particle. FIGURE 3B shows the interconnection between the sensor 418 of FIGURE 3A and the data acquisition board 161-G. The signals from the two extinction channels VE1 and VE2 are processed by the data acquisition board (DAB) 161-G to provide the speed of the particle. The speed of the particle is especially important in the classification of fiber neps as it is related to the mass of the entity. A particle with a larger mass, such as a seed coat nep, will not accelerate as rapidly in the flow stream 112 in the tapered section of nozzle 106 as a less massive particle and therefore will have a lower velocity while in the measurement volume. The first extinction channel signal VE1 is further processed to give the peak value of the signal (PE), the integrated value of the waveform above the threshold (AE) and the duration of the waveform above the threshold (TFE). Similarly, the scatter channel signal VS from the infrared scatter detector 440 is processed to yield PS, AS, and TFS. The signal from the fluorescence detector 442, VUV is coupled to a threshold comparator 444, whose threshold is set to respond to any significant amount of blue visible radiation above the electronic noise of the system, and the output of the comparator 444 is applied to the bus 213. The waveforms for a typical nep, shiny nep and seed coat nep are shown in FIG. 4 with the waveform parameters. With these waveforms in mind, the nep classification method described below may best be understood. Neps are classified according to the method illustrated in FIG. 5 in flow chart form. As illustrated in FIG. 6, the purpose of the classification method is to classify neps into groups, namely, mechanically generated neps, shiny neps and seed coat fragment neps. These classifications are further sub-classified as shown in FIGURE 6 and discussed below. The program (running on computer 18) waits at block 446 until a waveform appears on one of the channels. Then, it begins a series of three screening tests to determine if the event falls into one of the nep categories. If the event fails any of the three tests, control is passed to a trash classification program described hereafter. In the first test, the value of TFE must be small enough to exclude the possibility of counting a large clump of fibers, and the program checks whether TFE is less than X. The parameter X of block 448 is flow rate dependant and is normally chosen to exclude signals that are greater than approximately 30 µSec in duration when using current AFIS instruments. Second, the peak value of the signal must be greater than 21.3 V as shown in block 450. This defines the smallest group of fibers which will be defined as a nep. Third, the signal must contain enough information on the scatter channel, as determined by the ratio of PS/PE, to be processed as set forth in block 452. Any signal with a ratio less than 0.5 is not likely to be composed of fibers; i.e. such signals are usually due to trash particles and are ignored for the purposes of nep classification, but are further analyzed as possible trash particles. At block 454, the UV channel (output of comparator 444) is checked to see if the event was a polyester nep as determined by the signal on the UV channel having a peak value greater than the threshold voltage (VUT). If yes, the size of the polyester nep is calculated as shown in blocks 456 and 458. If no signal is found on the UV channel, the program tests the ratio of PS to PE again as set forth in block 460 to determine whether or not the event was shiny (immature) or mature. If the ratio is less than or equal to 0.75, the event was due either to an immature seed coat nep or shiny nep and the speed test as set forth in block 462 determines which type of entity the event was. If the speed is greater than Y, the program classifies and reports the event as a shiny nep as indicated at block 466 and if speed is less than Y, the event is classified and reported as an immature seed coat nep as indicated at block 468. The variable Y of blocks 462 and 464 is a flow rate dependant calibration parameter (expressed in meters per second (m/s)) that is optimized for particular system flow parameters. For a system operating at approximately 1.84 dm 3 /s (3.9 CFM), this value is typically 60 m/s. Once the particle is classified as either a seed coat nep or shiny nep it is sized as set forth in blocks 456 and 458. It is understood that separate sizing algorithms may be used for the different nep subclasses. Also, the speed used in this program is preferably the average speed calculated by averaging TB and TE and dividing the effective distance between detectors 430 and 432 in FIG. 3A by the average. Other speed calculations and measurements may also be used, such as a speed calculation based solely on TB, or solely on TE, or on an acceleration corrected time such as described US 5,410,401 entitled "Methods and Apparatus for Mechanically and Electronically Correcting Presentation of Entities in a Fluid Flow," filed December 31, 1992. The value Y must be calibrated depending upon the flow rate of the system and the manner in which speed is calculated. Because of the speed differences between mechanical neps and mature seed coat neps, any of the speed calculations mentioned above may be used to distinguish between and classify these two types of neps. If in block 460 the ratio of PS to PE is not less than or equal to 0.75, then the event was due to a mature entity and the event is tested as set forth in block 464 to determine if a mature seed coat nep was present. If speed is less than Y, it is determined that a mature seed coat nep is present, and the event is classified and reported as a mature seed coat nep as indicated at block 470 and then sized. If speed is greater than Y, there was no seed coat fragment, and the event is counted as a mature nep at block 472 and sized. The sizing program as set forth in blocks 456 and 458 convert the peak value on the extinction channel, PE, to a physical size by the calibration constant K1 (microns/volt). The length of the nep is preferably determined in this embodiment by multiplying TFE by the calibration parameter K2 which is the speed detected by the extinction detectors 430 and 432 as was also described previously. Statistics such as the standard deviation of diameters, the number of counts per unit weight in each of the classes and a size frequency histogram may then be calculated by the computer 18 (FIG. 1) based upon the classifications. It will be appreciated that neps may be further sub-classified using the system and methods discussed above. For example, sticky neps or "points" are found in cotton fibers and are typically caused by the sugars of insects that are harvested along with cotton. These sticky neps can cause gumming of the processing machinery and may be a concern. To detect sticky neps in the system described above, preferably, the infrared beam is chosen to have infrared frequency specific to a suspected sugar in the cotton and is chosen to avoid absorption by water. When a sticky nep is presented at the sensor 418, it will exhibit strong absorption of the infrared beam which will be detected by extinction detectors 430 and 432. Thus, once a nep is identified by the methods discussed above, it may be further sub-classified as a sticky nep or point by determining whether its absorption of sugar specific infrared light exceeds a predetermined threshold, which is determined by calibration for a particular system and will vary for different types of cottons from different geographical regions. Having described the nep sub-classification system above, the trash sub-classification system will now be described. However, before describing this system, a better understanding of trash, particularly cotton trash, may be had be reference to FIGS. 7 and 8 which show, respectively, a pie chart and illustrations of various types of trash. As shown in FIG. 7, trash may be divided into two broad classes or categories, fibrous and other. The category of "other" is not necessarily non-fibrous. For example, fiber fragments are classified as "other" because of their short length. Thus, it will be appreciated that the trash is being classified according to its physical characteristics. Generally, trash is considered to be fibrous if it has an aspect ratio of 3 or greater. Referring to FIGS. 7 and 8, it will be appreciated that bark and leaf or grass having an aspect ratio of greater than 3 will be classified as fibrous. Flake trash having an aspect ratio of less than 3 is considered "other" trash and, likewise, thick trash, dust and fiber fragments having an aspect ratio of less 3 are considered to be "other" trash. Thick trash which is illustrated in FIG. 8 is typically a thick seed coat fragment with only a few fibers attached or a fragment of bark. In general, thick trash is any trash having a geometry approximating a sphere or a cube. The exact definition of thick trash will depend upon selected parameters in the classification program described below. Referring now to FIG. 9A, there is shown a flow chart for classifying trash. This program begins at the circle labeled "T" and, referring to FIG. 5, it will be appreciated that the nep program is designed to transfer control to the trash program at three different positions in the program. Thus, the nep sub-classification program and the trash sub-classification program are designed to be able to run together, if desired. Of course, the trash program could run independently and this would be preferred where one knows that only trash will be detected by a particular or separate physical sensor system. The first step in the trash sub-classification in indicated by block 470 wherein the speed of an event is calculated. In this particular embodiment speed (S) is preferably calculated by averaging TB and TE [ (TB+TE)/2 ] and then dividing a constant (DCONST) by that average. Of course, DCONST is the effective distance between the extinction sensors 430 and 432 as shown in FIG. 3A. Of course, if the beam, for example beam 426, impinging upon the detectors, for example detectors 430 and 432, is converging or diverging, DCONST is appropriately corrected to compensate for the magnification or reduction caused by the diverging or converging beams. As indicated by block 472, the next step is to calculate the length of the event or entity using the formula L=S X TFE , where TFE is the time required for the entity to pass by one of the extinction sensors, L is length and S is speed. At decision step 474 the length is compared to a minimum length LMIN. If L is not greater than LMIN the program proceeds to point U indicated by character 476 and is transferred to another section of the program which will be described hereinafter. If L is greater than LMIN, the program proceeds to block 478 and calculates the aspect ratio (AR) which is the length (L) divided by the average diameter (DAV), where DAV is calculated using the formula DAV=AE/TFE . Proceeding to decision step 480, if the aspect ratio, AR is not greater than ARMIN, the event is regarded as a flake and the program passes to point "V" indicated by character 482. If AR is greater than ARMIN then the program continues to decision step 484. As previously discussed, by general industry agreement, an entity having an aspect ratio greater than 3 is considered fibrous. Thus, in the preferred embodiment, ARMIN is chosen to be 3. However, depending upon their application, it may be desirable to change the value of ARMIN in decision step 480. For example, in some applications, industry standards may define fibrous as an aspect ratio greater than 10. At decision step 484, the program compares DAV to a minimum threshold (DMIN). If DAV is not greater than DMIN, the program moves to block 486 and discards the data regarding it to be data produced by a fiber. If DAV is greater than DMIN, the program moves to a decision step 488 and determines whether speed is greater than a chosen speed bark maximum (SBM). If S is greater than SBM, the program classifies the trash as fibrous trash and it reports the length of the trash and the diameter of the trash. Preferably, the diameter of the trash is reported as being equal to DAV times a constant K3. The constant K3 is a calibration constant that is determined experimentally. If S is not greater than SBM, the program classifies the trash as bark trash, report's the length and reports the diameter, again, as K3 multiplied by DAV, as indicated by block 492. Returning to decision step 474, it will be recalled that if L was not greater than LMIN, the program transferred control to point U which is the sub-routine shown in FIG. 9B. Referring to FIG. 9B, the first decision step 494 compares the peak voltage (PE) to a threshold (PKDUST). If PE is greater than PKDUST, the program moves to decision step 496 where speed is compared to the constant (SSCFM) (Speed Seed Coat Fragment Max). If S is greater than SSCFM, as indicated at block 497, the program classifies the event as flake trash and reports the diameter of the trash as being equal to K4 multiplied by the square root of PE. If S is not greater than SSCFM, the program moves to block 498 and classifies the event as thick trash and reports the diameter as K4 multiplied by the square root of PE. K4 is a calibration constant and the constant PKDUST is chosen such that PE will be greater than PKDUST when a particle has a diameter greater than 500 microns. Referring again to decision step 494, if PE is not greater than PKDUST, the program moves to decision step 500 and determines whether speed (S) is greater than a constant (SDUST). If yes, the program classifies the event as a fiber fragment and reports the count of fiber fragments as indicated by block 502. If no, the program classifies the event as dust and reports the diameter as K4 multiplied by the square root of PE, as indicated by block 504. Referring to 9A and 9C, it will be recalled that if AR is not greater than a constant (ARMIN), the program moves to point 482 which begins another sub-routine, V. This sub-routine begins at step 506 where speed is compared to a constant (SSCFM). If yes, the program classifies the event as flake trash and reports the diameter as K5 multiplied by PE. If no, the program classifies the event as thick trash and reports the diameter, again, as K5 multiplied by PE. Having described the operation of the trash classification program, some additional details are provided below that are specific to a particular application of the invention. These details should be regarded as examples and not limitations. For example, the calibration parameters K1, K3-K5 are determined experimentally by placing known entities into the system. These parameters (K1, K3-K5) may be constants or curves. In the preferred embodiment, K4 is a curve which is stored within computer 18 in the form of a look-up table (PE), of selected peak extinction values (PE) and associated diameters. When a PE is sensed, the diameter is found by using the look-up table and interpolation where necessary. Referring to decision step 474, the length of the event was tested against LMIN. Preferably LMIN is 1mm, but other dimensions could be chosen. The philosophy for choosing this dimension is that, in this particular application, trash that has a length of less than 1mm is "other" trash. It is not fibrous trash. Referring to decision step 480, as previously mentioned, it is preferred to use ARMIN equal to 3. This decision step means that for trash to be classified as fibrous, it must have an aspect ratio of 3. Otherwise, it will be classified as "other." At step 484, the diameter of the trash is compared to DMIN. Preferably DMIN is 120µm which corresponds to 12 volts in the AFIS circuitry described above. The underlying reason behind this test is to ensure that fiber has not somehow thus far been classified as trash. If DAV is not greater than 120µm, the data are discarded as possibly being non-trash fiber data. Referring to decision step 488, the speed test is distinguishing between two types of fibrous trash. Grass and leaf trash, which is categorized as fibrous trash, will travel faster in an accelerating airstream than bark trash (which is also fibrous) because leaf and grass trash is less dense and usually has less mass. Consequently of course, bark is traveling at a slower speed than grass and leaf because of its mass and density. Referring to decision step 494, this decision is based entirely on size. If an event is smaller than 500 microns which is the industry standard cutoff, the program classifies it as dust or a fiber fragment. At decision step 500, SDUST is preferably chosen to be 64 meters per second. This constant is highly dependent upon the flow rate of the gas or air in a particular system, since extremely small particles such as dust and fiber fragments will move at approximately the flow rate of the airstream. Referring to decision steps 496 and 506, there is again a classification according to speed. In this particular application, SSCFM is chosen to be 30 meters per second and it functions to distinguish between flake trash and thick trash. In this case, flake trash has a greater surface area per unit weight than thick trash and, thus, will travel faster in an accelerating airstream. The actual value for SSCFM should be determined by calibration by injecting known flake trash and known thick trash and observing their speeds. As previously mentioned, these specific numbers should be regarded as examples and it will be understood that they will vary depending upon air flow rates, nozzle configuration, sensor system, amplification systems, etc. It should be noted that the values given above are for use in the system described with reference to FIG. 3A. If different gain values are used or different components are substituted, these values would naturally have to be changed to correspond to the modified system. One way to determine these values for a new system would be to drop a series of known entities through the sensor section and measure the values of the characteristic parameters. Then, these values could be provided to the computer for use in the classification program to be used with unknown test samples. It should be further noted that the sensor of FIG. 3A adds the UV light source 422, beam splitter 438, fluorescence detector 442 and its associated electronics. The remaining components function substantially as was described previously. While several embodiments of the invention have been described in the foregoing Detailed Description, it will be understood that the invention is capable of numerous re-arrangements, modifications and substitutions of parts without departing from the scope of the invention as defined by the appended claims.

Claims: Apparatus for measuring characteristics of entities in a sample of textile material including at least fibres, comprising supply means (16) for supplying a sample of textile material, processor means including a processor input and a processor output, said processor input being positioned and operable to receive the sample of textile material from said supply means, said processor means being operable for processing a sample, releasing the entities of the sample one from the others, individualizing said entities to produce single entities and producing entities at said processor output in an individualized condition, sensor means (418) for sensing characteristics of said entities, transporting means including an airstream for transporting the entities from the processor means in the airstream to and through said sensor means, analysis means for receiving signals from the sensor means, a first light source (420) for producing and directing light onto said entities along a first light path (426) in said sensor means in said airstream, a first extinction sensor (430) disposed within the sensor (418) to the side of said sensor airstream for sensing light disturbances caused by said entities in said sensor passing through said first light path and producing a first extinction signal (VE1) corresponding to the light extinction caused by said entities within said sensor (430), a second extinction sensor (432) positioned to the side of said sensor airstream in said sensor means, adjacent to said first extinction sensor (430), and being downstream from said first extinction signal sensor relative to said airstream, said second extinction sensor (432) for sensing light disturbances caused by said entities in said sensor passing through said first light path and producing a second extinction signal (VE2) corresponding to the light extinction caused by said entity within said sensor (432), charcterised by a second light source (422) for producing and directing ultraviolet light (UV) onto entities along a second light path (428) in said sensor means in said airstream, light collection and direction means (434), for collecting light forward scattered by entities passing through said first and second light paths of said first and second light sources and directing such light along a first desired path, splitter means (438) disposed in the path of said light directed by said light collection and direction means (434)for allowing a portion of light directed by said collection and direction means to continue on the first desired path and directing the remaining portion along a second desired path, forward scatter sensor means (440) disposed in said first desired path adapted to be responsive to forward scattered light from said first light source for producing a forward scatter signal (VS)corresponding to received forward scattered light, fluorescence sensor means (442) disposed in said second desired path adapted to be responsive to forward scattered light emitted by said entity when said entity is in the path of said second light source (422), said emitted light being emitted as a result of fluorescence of the entity, said fluorescence sensor further being unresponsive to forward scattered light from said first light source, for producing a fluorescence signal corresponding to received light, analysis means (18) for receiving said first (VE1) and second extinction signals (VE2), said forward scatter signal and said fluorescence signal as characteristic signals, analyzing said characteristic signals to identify segments of said characteristic signals that correspond to one of said fibres, trash or neps, said analysis means being operable to compare a selected one of said first extinction signal, second extinction signal or forward scatter signal to a predetermined threshold. Apparatus according to claim 1, wherein said analysis means is a computer including digital signal processing means. Apparatus according to claim 1, wherein said first light source is an infrared source. Method for measuring characteristics of entities in a sample of textile material including at least fibres, comprising: supplying a sample of textile material, processing the sample to produce individualized single entities, transporting the entities in an airstream to and through sensor means, sensing at least one characteristic of a portion of the entities from each single entity and generating characteristic signals, by producing and directing light along a first light path to impinge on said entities, sensing light disturbances caused by said entities in said first light path (426) and producing a first extinction signal (VE1) corresponding to the light extinction caused by said entities, sensing light disturbances caused by said entities in said first light path and producing a second extinction signal (VE2) corresponding to the light extinction caused by said entity, characterised by producing and directing ultraviolet light (UV) along a second light path to impinge on said entities, transporting entities through said first and second light paths, collecting light forward scattered by said entities passing through said first and second light paths and directing such light along a first desired path, allowing a portion of light directed along said first desired path to continue on the first desired path and directing the remaining portion along a second desired path, producing a forward scatter signal (VS) corresponding to received forward scattered light scattered by an entity passing through said first and second light paths, emitting light as a result of fluorescence of the entity, for producing a fluorescence signal (VUV) corresponding to received light, analyzing said signals by comparing a selected one of said first extinction signal (VE1), said second exctinction signal (VE2) and said forward scatter (VS) signal to a predetermined threshold, if said selected one of said signals exceeds the threshold, to compare one of said first or second extinction signals to the forward scatter signal, to produce a nep detect signal when the selected one signal exceeds the threshold and the ratio of the forward scatter signal to one of the extinction signals exceeds a predetermined ratio and to further identify and distinguish signals as corresponding to one of several types of neps based upon the values of said characteristic signals and the presence or absence of a fluorescence signal, and to produce a trash detect signal when the selected one extinction signal exceeds the threshold and the ratio of the forward scatter signal to said one of the extinction signals does not exceed the predetermined ratio, if said selected one of said extinction signals does not exceed the threshold, to compare the amplitude of said one of said extinction signals to the duration of said one of said extinction signals and based in part on such comparison to determine whether said entity is a fibre or trash. Method according to claim 4, charcterised in that the fluorescence signal is compared to a threshold and the entity is classified as a polyester nep, if the fluorescence signal is greater than the threshold.

Inventors: BALDWIN JOSEPF C, GALYON MICHAEL E, SHOFNER FREDERICK M, YOUE-T CHU, BALDWIN, JOSEPF C., GALYON, MICHAEL E., SHOFNER, FREDERICK M., YOUE-T, CHU
Applicants: ZELLWEGER USTER INC, ZELLWEGER USTER, INC.
Application year: 1993
Main classification: G01N33
IPC codes: D06H3, G01N15, G01N33, G01N21, D01G31