DE4341685A1 - An optical test set for yarn structure, giving clear fibre images - Google Patents

Abstract

An optical test set for yarn structure comprises: transparent cuvette (11), esp. of square cross section, to hold the yarn (12) sample in a predetermined, pref. elongated shape, appts. (13) to illuminate the sample with scattered light and optical observation appts. (14) producing at least one, pref. magnified, picture of the yarn and comprising at least one objective (16) to capture at least most of the light penetrating the yarn and at least one high sensitivity, esp. video, camera (17,17') directly or indirectly connected to a high resolution monitor (18). Also claimed are: (A) a mathematical method, (B) a programmed computer.

Description

The invention relates to an optical yarn structure testing device according to the preamble of claim 1, a device according to the preambles of claims 13, 14 and one Method according to the preambles of claims 15 and 16.

Such optical yarn structure testing devices are used to determine fiber orientation in fiber tapes and for testing the geometric properties of yarns and threads det. This includes the inner yarn structure, the diameter and the outer shape of the yarn, testing the yarn hairy and the geometric defects in the yarn (textile technology 24 (1974) 3, pages 168 to 171). In the known optical Yarn structure tester enters from a projection lamp outgoing and reflected by a spherical mirror Luminous flux into a condenser system is changed by a change self-filtered and with the help of two exposure prisms divided into two mutually perpendicular bundles. By the intersection of the two bundles runs vertically to the optical axis the yarn to be examined, which is in the middle with transparent flat walls is a cuvette, the yarn ver parallel to the walls running. While examining the inner yarn structure the cuvette is filled with an immersion liquid. On the opposite side of the two perpendicular to each other there are other light entry walls Special prisms that light perpendicular to each other bundles that have passed through or past the yarn are again in the same direction Combine light bundles and guide them into a lens, wel ches either on a focusing screen or a film two juxtaposed enlarged images of the yarn are generated, which are perpendicular to each other from the two observations correspond to the directions.

Detecting the structural arrangement of fibers inside  half of the yarn can be favored in that the Production of the yarn of the drawstrings a small amount Number of colored fibers is added, preferably in such an amount that in a cross section of the yarn about a colored fiber is present. This can be done at the optical observation clearly from the undyed fibers distinguished and so exactly in their geometric course be followed.

The well-known optical yarn structure tester delivers especially when examining yarn from cotton fibers often unsatisfactory results because of the Coloring optically highlighted fibers in their geometric Difficult due to blurred image and are incompletely traceable.

The aim of the invention is therefore an optical Yarn structure testing device of the type mentioned at the beginning create, by means of which also when examining from Yarns made of cotton fibers are optimally recognizable speed of individual, especially dyed fibers within the Yarn structure is guaranteed.

To achieve this object, the invention provides one optical yarn structure tester of the aforementioned Genus before that the lighting device with the yarn Stray light illuminates and the observation device little least at least a larger fraction of that by Lens arrangement detecting yarn passed through and at least one highly sensitive camera, in particular Video camera with directly or indirectly connected high up resolving monitor.

Surprisingly, it has been shown that when using the litter unsuitable for exact optical images  the recognizability of individual, especially stained Fibers within a cotton yarn are substantially verbs sert. However, this requires that the lens used for the illustration is the one directed to the thread Scattered light recorded as much as possible, which is why z. B. the Macro Vario lens setting on highly sensitive video cameras are particularly suitable. Preferred for the purposes of inven is a 3-CCD video camera.

The video monitor can either be connected directly to the video camera be connected, or it will be on a video first recorder cached the video image and then reproduced on a video monitor. It is also purpose moderately to the camera or video monitor Video image printer connected, with which certain Bil which can be recorded in the form of a video photo.

Advantageous further developments of the invention Test device are by claims 2 to 12 featured.

In addition to the known optical merging of the Beam paths perpendicular to one another according to claim 3 Video observation of the yarn is also suitable for two Electro pictures taken with separate video cameras niche on a video monitor, like the one in Claim 4 is defined.

Claims 5 and 6 characterize two possibilities investigating yarn the litter used in the invention to generate light. The Ver is particularly advantageous here using a cuvette with light-scattering light entry walls because of the special light-diffusing elements can be avoided and in this way the light scatter particularly close to the yarn. This is for the purpose of  Maintaining sufficient light intensity for video recording advantage.

Basically, the light-scattering elements could too inside the cuvette between the light entry walls and the yarn can be arranged what be by light scattering would reduce further losses.

To generate the best possible image quality, the Cuvette can be filled with an immersion liquid has the same refractive index as the yarn to be examined. Furthermore, the immersion liquid is said to have good wetting of the yarn, so that the liquid quickly into the Voids penetrate. A mixture of is preferably used two liquids with different refractive indices, so that you get exactly the refraction by the mixing ratio index of the yarn to be examined. By tree the refractive index is usually in the range from 1.5428 to 1.552. A preferred immersion liquid consists of a mixture of methyl salicylate and cis- Methyl cinnamate, in the case of cis-methyl cinnamate in an amount is added to the desired refractive index adjust.

Ideally, the colored fibers are added to the Cotton flake so that the dyed fibers all work go through steps that are normally used in the manufacture of yarn be carried out. The addition at the very beginning has however, the disadvantage that very large amounts of yarn with dyed fibers must be made for the Examination of the fiber structure are not needed. Therefore according to the invention, the colored fibers are added expedient in the stretch band as a colored band. Doing so the mixture of colored tape and uncolored tape that is about 1: 3  additional undyed tapes added to the 1: 3 mixture are not subjected to. The colored part of the gar nes is therefore stretched three times over the others unstained ribbons that are only stretched twice. The Amount of admixture of colored fibers should be such that with the resulting yarn in every cross section essentially there is only one colored fiber. So the relationship depends on the fineness of the yarn and is for fine yarns about 1: 150. The yarn is then preferably at 60 ° C. 4 bleached for a long time, using H₂O₂ / NaOH (10 g / l H₂O₂, 2.8 g / l NaOH) can be used to remove Verunreini in the cotton used in the structural examination can interfere with eliminating. Then with distilled water washed and dried.

Any dye can be used to dye the fibers color it dark, preferably black. By tree wool fibers can e.g. B. vat and reactive dyes be det.

It has been shown that in particular the combination of Above mentioned immersion liquid with the light scattering Means before the cuvette and the use of one or several highly sensitive video cameras for observation too with cotton yarns leads to optimal test results because due to the excellent image quality of the geometric Course of the particular dyed individual fibers on the high-resolution video monitor can be tracked exactly.

An advantageous device for determining the structure of a yarn mixed with measuring fibers with a optical test device according to the invention results from the Claims 13 and 14.

A preferred method of determining the structure of a  yarns mixed with measuring fibers can be found in the claims 15 and 16.

Advantageous developments of this method are through characterized claims 17 to 20.

The evaluation of the images of the fiber yarn is generally in two perpendicular planes like described assessed. After this assessment, the considered measurement images in a number of measurement classes classified. Then the number of samples in the individual measurement classes and an average coefficient determined from all samples. This takes place in the Way that the number in each class with the class coefficient is multiplied for weighting, the numbers obtained are summed up and by the Number of total measured fibers can be divided. This then gives the average coefficient as Statement about the fiber parallelism in the measured yarn, from which the samples were taken.

This procedure is complex and time-consuming, so that automatic evaluation is desirable.

Such an automatic evaluation can be based on the invention do the following.

First the fiber lengths are entered into a computer, that has the processed fiber material. With synthetic fibers it is a rectangular stack, so the stack length in a simple manner from this stack of rectangles is leading. With cotton, the fibers are very under different lengths. It is a so-called Triangle stack. The middle stack is entered here. This middle stack corresponds to the actual fiber length  only on average, with a sufficiently large number of experiments however, it is representative of the fiber length. With a optical measuring device is now the horizontal length of the Fiber measured as shown in the picture. This expediently takes place with a so-called class mask according to the measurement classes, as they already do from the visual Method are known. The number of measurement classes can ver enlarged and thus also the measurement can be refined. These optically recorded signals are then in accordance with the Class masks classified in the corresponding measurement classes. Furthermore, the computer determines the number in the individual measuring classes, from which it then - as already above described - an average coefficient determined as Measure of fiber parallelism.

In the described method, it is also possible to use the length class determined directly in the class mask with the given stack as total fiber length ins To set the ratio and thus the for each individual sample To determine the degree of stretching and then from the sum of the The degree of stretching of the individual samples is the average To calculate the degree of stretch for the yarn.

According to another method, the exact length of the Fiber recorded from the three-dimensional image. this will enabled because the fiber is shown in two levels. Then, similarly to the method described above, the straight distance between the beginning and end of the shown fiber determined, but this is not only with a Class mask, but made to measure. The computer determined from these two values (actual exact Length of the fiber and straight line distance between the beginning and ender of the fiber) the degree of stretching in each individual Case. By adding up the individual degrees of stretch an average degree of stretch is then determined as above  already described. This way you can automatically with the yarn structure measuring device according to the invention Yarn structure of fiber yarns, especially cotton fiber yarn, determine in a simple and rational way.

According to the invention, the two views of the yarn in two mutually perpendicular planes are therefore not only assessed by visual inspection; rather, an automatic evaluation of the observation results, as stated above, is preferred. It is assumed here that the added colored fibers can be given a very specific length and preferably also given, from which the position and orientation of the fibers in the finished yarn can then be derived. For example, five different classes of fibers (fiber coefficient K _F ) can be differentiated as follows:

K1: essentially stretched (fiber coefficient K _F1 = 0.89)
K2: one end of the fiber is double (fiber coefficient K _F2 = 0.63)
K3: fiber lies twice (fiber coefficient K _F3 = 0.35)
K4: the fiber is multiple (fiber coefficient K _F4 = 0.12)
K5: multiple layers and wraps (fiber coefficient K _F5 = 0.05).

The parallelism of the fibers in the yarn can be deduced from this calculate using the following formula:

in which
K _{F is} the mean fiber coefficient and
n₁, n₂,. . . means the amount of fiber in classes K1, K2 etc.

The measurement results can be saved in a connected computer can be entered, where then according to the formulas above resulting evaluation is carried out automatically. For this it is only necessary that the correspondingly measured fiber amounts can be entered, since it from these then taking into account the well-known Festig fiber can calculate the yarn tenacity.

The invention is described below, for example, with the aid of Drawing described; in this shows:

Fig. 1 is a schematic view of an optical yarn structure tester according to the invention and

Fig. 2 is a corresponding view of another form of Ausfüh.

According to Fig. 1 shows a lamp 26 generates by means of a concave mirror 27 and a condenser system 28, a parallel light bundle 29, which is a special beam splitter prism is incident on the flat front surface 30 31. Within the beam splitting prism 31 there is a 45 ° to the direction of the parallel light beam 29 inclined splitter mirror surface 32 on which 50% of the light beam 29 is deflected by 90 ° to a flat side surface 33 , to the side surface 33 again by 90 ° To be deflected first light exit surface 34 , which is perpendicular to the direction of the parallel light beam 29 .

The other 50% of the light beam 29 go through the divider mirror surface 32 to meet on a further, parallel to the side surface 33 flat side surface 35 on which the light beam is deflected by 90 ° to another light exit surface 36 , which with the light exit surface 34 includes a right angle.

In this way, an illumination device 13 is created with two mutually perpendicular light beams 20 , 21 , which overlap in an intersection area in which a cuvette 11 with a linearly stretched yarn 12 located therein and extending perpendicular to the plane of the drawing is arranged.

Seen in the beam direction, behind the beam splitting prism 31 and the cuvette 11 and in the extension of the light bundles 20 , 21, there is an observation device 14 which, in the beam path, has surface 32 formed beam deflecting prisms 38 , 39 which are symmetrical to the divider mirror and which extend to them at an angle of 90 ° deflect light beams 20 , 21 impinging on each other and perpendicular to the light bundles 20 , 21 running flat light entry surfaces 40 , 41 in such a way that they emerge parallel to one another from flat light exit surfaces 42 , 43 which run at 45 ° to the light entry surfaces 40 , 41 and are aligned with one another are.

Immediately behind the light exit surfaces 42 , 43 is a high-resolution 3-CCD video camera 17 with a macro lens arrangement 16 , which is connected via a cable 44 to a high-resolution video monitor 18 . A video image printer 45 is connected to the video monitor 18 via a cable 46 .

The beam deflecting prisms 38 , 39 and the video camera 17 form an observation device 14 .

The cuvette 11 with a square cross-section is thus arranged in a substantially square cross-section in facing space, which is limited by the light exit surfaces 34 , 36 of the beam splitting prism 31 and the light entry surfaces 40 , 41 of the beam deflecting prisms 38 , 39 . The cuvette 11 has transparent flat side walls which run parallel to the light exit surfaces 34 and 36 and the light entry surfaces 40 and 41 , respectively.

Between the light exit surfaces 34 , 36 of the beam splitting prism 31 and the parallel parallel light entry surfaces 22 ', 23 ' of the cuvette 11 according to the invention, focusing screens 22 , 23 are arranged.

The cuvette 11 contains, in addition to the straight, tensioned cotton yarn 12 extending perpendicular to the drawing plane, an immersion liquid 15 . The yarn is preferably located in the central axis of the cuvette 11 forming a cylinder with a square cross section. The yarn 12 is introduced and held within the cuvette 11 in the same manner as that described in Textile Technology 24 (1974) 3, page 169.

In the case of cotton yarn, the immersion liquid 15 located in the cuvette 11 is a mixture of methyl salicylate and cis-methylcinnamate with a refractive index in the range from 1.5428 to 1.552.

The function of the optical yarn structure tester described is as follows:
Up to the light exit surfaces 34 , 36 of the beam splitting prism 31 , the light divided into two mutually perpendicular light beams 20 , 21 is sharply focused so that a high light intensity is achieved up to these surfaces.

On the focusing screens 22 , 23 there is a strong light scattering, which ensures that the yarn 12 located in the cuvette 11 is applied not only from the direction of the light beams 20 , 21 , but from a variety of directions of light. The closer the focusing screens 22 , 23 are to the yarn 12 , the greater the angular range from which light strikes the yarn 12 . However, only those scattering angles make sense in which the light that has passed through the yarn 12 under these scattering angles still enters the light entry surfaces 40 , 41 of the beam deflection prisms 38 , 39 . It is therefore also important according to the invention that the light entry surfaces 40 , 41 are as close as possible to the light exit surfaces of the cuvette 11 and are of a sufficient size. Also, the inner structure of the beam deflecting prisms 38 , 39 must take into account the considerable scattering angles of the incoming light in the sense that as far as possible all incoming scattered light surfaces 42 , 43 emerge from the light exit.

It is important further that the opening of the lens assembly 16 of the video camera 17 sufficiently large and the distance between the lens assembly 16 is sufficiently small from the light exit surfaces 42, 43 so that the surfaces of the light output is largely detected 42, 43 exiting scattered light completely by the lens assembly 16 and contributes to the generation of images in the video camera 17 .

In this way, even with cotton fibers, a complete dige and exact illustration of the preferably colored Ein cell fibers achieved.

While in the embodiment of FIG. 1, the cross beam 20, can be made 21 before entering the video camera 17 optically again parallel to each other are shown in Fig. 2 instead of the Strahlumlenkprismen 38, 39 and a video camera 17, two at an angle of 90 ° zuein other arranged highly sensitive 3-CCD video cameras 17 , 17 'used, which observe the yarn 12 in the direction of the light bundles 20 and 21 and are also designed and arranged as the video camera 17 of FIG. 1st

In this way, instead of the observation beam paths according to FIG. 1, which are kinked several times in the beam deflection prisms 38 , 39, straight observation beam paths are created between the cuvette 11 and the lenses 16 of the video camera 17 , 17 '.

The video signals of the two video cameras 17 , 17 'are supplied via cables 44 , 44 ', a video processor 19 and a cable 44 '' to the video monitor 18 . In the video processor 19 , the two images of the video camera 17 ', 17 ''are processed such that they appear on the screen of the monitor 18 side by side or one below the other.

Reference list

11 cuvette
12 yarn
13 lighting device
14 observation device
15 immersion liquid
16 lens arrangement
17 , 17 ′ , 17 ′ ′ video camera
18 video monitor
19 video processor
20 light beams
21 light beams
22 focusing screen
23 focusing screen
22 ′ light entry wall
23 ′ light entrance wall
26 lamp
27 concave mirror
28 condenser system
29 parallel light beams
30 front surface
31 beam splitting prism
32 partial mirror surface
33 side surface
34 light exit surface
35 side surface
36 light exit surface
37 intersection area
38 beam deflection prism
39 beam deflection prism
40 light entry surface
41 light entry surface
42 light exit surface
43 light exit surface
44 cables
45 Video image printers
46 cables

Claims (20)

1. Optical yarn structure tester with a cuvette ( 11 ) containing an always sion liquid, preferably a rectangular, in particular square cross-section, in which the yarn ( 12 ) to be examined can be arranged in a predetermined position, preferably in a stretched form, with a lighting device ( 13 ) for the yarn ( 12 ) located in the cuvette ( 11 ) and an optical observation device ( 14 ) with which at least one preferably enlarged image of the yarn ( 12 ) located in the cuvette ( 11 ) by means of the light emanating from the yarn ( 12 ) and passing through translucent walls of the cuvette ( 11 ) to the observation device ( 14 ), characterized in that the lighting device ( 13 ) illuminates the yarn ( 12 ) with scattered light and the observation device ( 14 ) at least a at least a larger fraction of the L passed through the yarn ( 12 ) ichtes capturing transmitting lens arrangement ( 16 ) and at least one highly sensitive camera, in particular video camera ( 17 , 17 ') with a directly or indirectly connected high-resolution monitor ( 18 ). 2. Apparatus according to claim 1, characterized in that the observation device ( 14 ) observes the yarn ( 12 ) from two mutually perpendicular sides and that the lighting device ( 13 ) illuminates the yarn ( 12 ) preferably from two mutually perpendicular sides . 3. Apparatus according to claim 2, characterized in that the two observation beam paths are brought together optically and directed to the same camera ( 17 ). 4. Apparatus according to claim 2, characterized in that the two observation beam paths from separate video camera ( 17 , 17 ') are detected and the video images of the two video cameras ( 17 , 17 ') electronically combined by a video processor ( 19 ) and on a common seed monitor ( 18 ) are reproduced. 5. Device according to one of the preceding claims, in which in the direction from which the observation (s) on the cuvette ( 11 ) takes place or takes place, preferably at least largely parallel light beams ( 20 , 21 ) sent to the cuvette ( 11 ) are characterized in that a light-scattering element, in particular a matt disc ( 22 , 23 ) or matt paper paper, is arranged directly in front of the cuvette ( 11 ) in the light bundle ( 20 , 21 ). 6. Device according to one of claims 1 to 4, in which, in the direction from which the observation (s) on the cuvette ( 11 ) takes place or take place, preferably at least largely parallelized light beams ( 20 , 21 ) to the cuvette ( 11 ) be sent, characterized in that the light entry walls ( 22 ', 23 ') of the cuvette ( 11 ) itself light-scattering, z. B. are designed as a focusing screen. 7. Device according to one of the preceding claims, characterized in that the immersion liquid ( 15 ) has a refractive index which corresponds to the refractive index of the yarn under investigation. 8. Apparatus according to claim 7, characterized in that the  Immersion liquid is a mixture of methyl salicylate and is cis methyl cinnamate. 9. Apparatus according to claim 7 or 8, characterized in that the immersion liquid has a refractive index in the Range from 1.5428 to 1.552 if that's too under searching yarn is made of cotton. 10. Device according to one of the preceding claims, characterized characterized in that the yarn to be examined a contains a small number of colored fibers. 11. Apparatus according to claim 9, characterized in that in each cross section of the yarn essentially only one dyed fiber is present. 12. Apparatus according to claim 10 or 11, characterized in that to darken the colored fibers vat and / or Reactive dyes are used. 13. Device for determining the structure of a especially dyed measuring fibers with yarn an optical test device according to one of the preceding Claims, characterized in that the test device with is coupled to a computer in which the center stack the measuring fibers contained in the testing yarn and corresponding classes for given length ranges as well as the corresponding length range Coefficients can be entered and which way It is programmable that the number of prepared Fibers per class determined and from the determined measuring fibers, taking into account the Quantity distribution of the measuring fibers to the individual classes and thus on the individual coefficients, one Average coefficient determined.   14. Device for determining the structure of a especially dyed measuring fibers with yarn an optical testing device according to one of claims 1 to 12, characterized in that the test device with a Computer is coupled, which is so programmable that it from each point of the length of the measuring fibers found the position in the room determined and from the comparison of the measured points the actual stretched Total length of the measuring fibers calculated that he also the Extension of the measuring fibers along the yarn axis determined and in relation to the stretched length of the measuring fibers sets to a coefficient for the To calculate the length utilization of each fiber length, and that finally from the coefficients obtained taking into account the fiber distribution on this Coefficients an overall coefficient for the fiber length utilization is determined. 15. Method of determining the structure of a preferably dyed measuring fibers with added yarn which the measuring fibers in defined classes, the each assigned a previously defined coefficient is grouped and quantified per class and then by dividing the sum that results from the addition of the products of each class counted fiber quantity with that of this class in each case assigned coefficient is formed by the Total of the total counted in all classes Fibers an average coefficient is formed in particular with the device according to one of the preceding Claims 1 to 12 and / or a device according to Claim 13 or 14, characterized in that a Middle stack of those contained in the yarn to be checked Measuring fibers is calculated as a function of this  Middle stacks and from the possible fiber lengths uses the longitudinal extension of the fibers in the yarn corresponding classes and assigned to them Coefficients are determined that the measuring fibers according to the length of the fibers in the yarn grouped into the specified classes and then taking into account the per class determined Fiber quantities and the predetermined coefficients of Average coefficient is determined. 16. Method of determining the structure of a preferably dyed measuring fibers with added yarn which the measuring fibers in fixed classes grouped, each with a previously defined Is assigned coefficient, and per class in quantity and then dividing the sum, that from the addition of the products of each class counted fiber quantity with that of this class in each case assigned coefficient is formed by the Total of the total counted in all classes Fibers an average coefficient is formed in particular with the device according to one of claims 1 to 12, and / or a device according to claim 13 or 14, characterized in that from each point the Length of the detected measuring fibers the position in the room it is determined that from the comparison of the measured Points in space the stretched length of the measuring fiber is calculated that the fiber extension along the Garnachse is determined and in relation to the stretched length of the measuring fiber is set to one Coefficients for fiber length utilization too calculate, and that taking into account the number of counted measuring fibers an overall coefficient for the Fiber length utilization is determined.   17. The method according to claim 15 or 16, characterized characterized in that the coefficient is from the ratio stretched length of the measuring fiber for fiber extension lengthways the Garnachse is calculated. 18. The method according to any one of claims 15 to 17, characterized characterized in that to prepare a test Yarn fiber material in flake form, in particular colored and then in the usual way a sliver is formed from this, which then not with the introduction of slivers prepared fibers is warped. 19. The method according to one or more of claims 15 to 18, characterized in that the prepared, especially dyed fibers under existing sliver Addition from unprepared fibers existing slivers several times, especially two to warped three times and then into a yarn is spun in such a way that the prepared Fibers are distributed so that in each cross section of the spun yarns essentially only one at a time such as serving as measuring fiber is included. 20. The method according to one or more of claims 15 to 19, characterized in that the yarn to be tested two bundles of light crossing at right angles is exposed in the immediate vicinity of the testing yarns are converted to flare on the other side of the yarn to be tested To make measuring fibers visible in their position and / or around generate digital values for evaluation.