CH699123B1 - Apparatus for use in spinning preparation or Ginnerei for detecting foreign parts in plastic. - Google Patents

Abstract

A device for use in spinning preparation or ginning for detecting foreign parts (34) of plastic, such as polypropylene tapes, polypropylene fabrics and polypropylene films, in a fiber material stream (D), e.g. made of cotton, comprising a light source (18) for polarized light for the transillumination of the fiber material stream (D) and contained in the fiber material flow (D), transmittable said foreign parts (34). The apparatus further comprises a detector means (13) for detecting the altered polarized light transmitted through the transmittable foreign parts (34) and another ultraviolet light source (43 1 to 43 4) for illuminating the fiber material stream (D) and contained in the fiber material stream , non-translucent said foreign parts (34). The detector device (13) is designed and arranged such that it detects light converted from the non-translucent foreign parts (34) from ultraviolet light to visible light and both the transilluminable and the non-transmittable foreign parts (34) are detected and separated from the fiber material (40 ) differs in the fiber material flow (D).

Description

The invention relates to a device for use in the spinning preparation or Ginnerei for detecting foreign parts made of plastic, according to the preamble of claim 1.

A problem in the operation of optically operating Fremdfaser- or Fremdteilausscheidern in spinning preparation machines for cotton or man-made fibers is that these bright or transparent plastics (such as packaging films or packaging fabric of polyethylene or polypropylene) due to the low optical contrast only insufficient or not recognize can.

In a known device (EP 0 545 129 B) for detecting polypropylene fibers in silk wrap two images are compared. One is created by illuminating with polarized light, the other is created by illuminating with white light. The material must be present in substantially parallel aligned silk fibers. The evaluation method requires the comparison of both pictures. So that both images can be brought to coincidence, the material is conveyed on a conveyor belt with motion synchronization under both inspection points. A device is described which requires only one camera. But you still have to take two pictures (one with polarized light, one with white light). For this purpose, the lights are sequenced, so that both images can be recorded by just one camera. For this purpose, however, the interruption of the material movement is required, wherein the sampling operations are carried out sequentially and the silk fiber blanket is advanced gradually. The device is complex plant. In particular, disturbing the switching of lighting, the discontinuous material transport and the taking of two images. Another significant disadvantage is that such packaging materials and waste plastics can not be detected which are not detectable by irradiated polarized light, e.g. dense or thick packaging residues. In the same way, plastic types which do not change the polarization state of the transmitted polarized light are not detectable.

The invention is therefore an object of the invention to provide a device of the type described above, which avoids the disadvantages mentioned, which enables the effective detection of white and / or transparent plastic parts in a structurally simple way in particular.

The solution of this object is achieved according to the invention by a device having the features of independent claim 1.

According to the invention, the detection is combined with polarized light with the detection with UV light, without it essential components such as cameras, inspection rooms, glass channels, or evaluation must be duplicated and without mutual interference of the two detection methods takes place. This arrangement concentrates the necessary components in the smallest of spaces and thereby saves installation space. There is a combined application of different wavelengths (visible light / UV light) and different polarization states (polarized / unpolarized). It is dispensed with switching the lighting and the discontinuous material transport, because not two images, but only one image is taken, which is illuminated simultaneously with both light sources. Another advantage is the possibility of simultaneous illumination and image acquisition, so that on the one hand no convergence of the two components subsequently generated and no temporal resolution reduction due to double image acquisition takes place. According to the invention, (without visible spectral components) is illuminated unpolarized (incident light) and polarized with visible light (transmitted light). This combination produces an image that can be recorded by a camera without switching / flashing the illumination and thus also includes both effects by changing the polarization state as well as by fluorescence. In this way, packaging materials and waste plastics are detected in fiber materials, which are not visible with polarized light. In certain chemical fibers and also in plastics produced with optical brighteners, the radiated UV light is converted by a fluorescence effect into visible wavelengths. This is then detectable by normal camera systems. The camera is not sensitive to the radiated UV light. Detection only takes place when the UV light is converted into visible light by fluorescence effects. As a result, it is possible to detect the widest possible variety of varieties of plastic foreign parts. In addition, dense or thick plastic residues or types of plastic that do not change the polarization state of the irradiated polarized light are detected.

The dependent claims have advantageous developments of the invention the subject.

The invention will be explained in more detail with reference to exemplary embodiments illustrated in the drawings.

It shows:

[0009] <Tb> FIG. 1 <sep> the device according to the invention on a Fremdteilerkennungs- and -ausscheidevorrichtung with horizontal transport channel, <Tb> FIG. 2 <sep> the device according to the invention on a Fremdteilerkennungs- and -ausscheidevorrichtung with lighting devices for polarized top light and UV incident light, vertical transport channel and straight camera directive, <Tb> FIG. 3 <sep> a device like FIG. 2, but with a deflected camera directive, <Tb> FIG. 4 <sep> an embodiment with two detection devices, <Tb> FIG. 5 is a schematic side view of a device with a glass channel and a lighting device for polarized overhead light, <Tb> FIG. 6 Fig. 7 is a plan view of a blower having a plurality of blowing nozzles arranged across the width, Block diagram of an electronic control and regulating device to which two sensor systems and two blower devices are connected, <Tb> FIG. 8 <sep> the device according to the invention for a 4-roll cleaner and <Tb> FIG. 9 <sep> the device according to the invention after a 1-roll cleaner; and <Tb> FIG. 10 <sep> the device according to the invention on a Fremdteilerkennungs and -ausscheidevorrichtung with vertical transport channel.

Referring to Fig. 1, in an apparatus for detecting and eliminating foreign matters, e.g. Trützschler Fremdteilausscheider SECUROMAT PROP SP-FP, the upper inlet opening of a hopper 1 associated with a means for pneumatically feeding a fiber-air stream A, the (not shown) fiber material transport fan, a stationary air-permeable surface 2 for separation (deposition) of the fiber material B of Air with air discharge and an air flow guide means 3 having movable elements, wherein a reversible guiding of the present in the air flow fiber material back and forth across the air-permeable surface 2 takes place and the fiber material following the impact substantially by gravity from the air-permeable surface 2 drops and enters down into the hopper 1. The low speed rollers 4a, 4b have a dual function; They serve as take-off rolls for the fiber material B from the hopper 1 and at the same time as feed rollers for the feeding of the fiber material B to a fast-running opener roller 5. The filled arrows represent fiber material, the empty arrows represent air and the semi-filled arrows represent an air flow with fibers.

The total area of the opener roller 5 is an optical sensor system 6, e.g. Line camera 6 (CCD camera) with electronic evaluation for the detection of foreign substances, in particular with brightness and / or color deviations assigned. The sensor system 6 is connected via an electronic control and regulating device 35 (see Fig. 7) to a device 7 for separating the foreign substances (see Fig. 6). The device 7 is able to produce a short-term blowing air flow, which extends in the direction of the clothing surface and generates a suction air stream, which removes the impurities together with a few fibers from the clothing surface and discharges into a channel 10.

The optical sensor system 6 with the camera, e.g. Color line camera, is arranged obliquely above the opener roller 5 close to the outer wall of the hopper 1. As a result, a compact, space-saving construction is realized. The color line camera 6 is directed towards the clothing of the opening roller 5 and is capable of colored foreign matter, e.g. red fibers, visible in the fiber material. The camera 6 comprises the entire area across the width of the opening roller 5, e.g. 1600 mm. The opener roller 5 rotates in the direction of the curved arrow in the counterclockwise direction. In the direction of rotation of the optical sensor system 6, the means 7 for generating a Blasluftstrom downstream, the nozzles are aligned in the direction of the clothing surface of the opening roller 6, that a short-term sharp air jet flows approximately tangentially with respect to the clothing surface. The sensor system 6 is connected via an evaluation device and an electronic control and regulating device with the device 7 in connection, which is associated with a valve control 8. If the camera 6 has detected an impurity in the fiber material on the clothing surface on the basis of comparison or setpoint values, a short air blast is ejected via the valve control 8 at high speed with respect to the clothing, the impurity from the fiber coating on the clothing with few Outgoing fibers through a suction air stream and then leads away through an evacuated channel 10.

Through a channel, a blast of air flows approximately tangentially to the opener roller 5, dissolves the fiber layer (good fibers) from the clothing and flows as a fiber-air flow D through a fiber transport line 11 to the glass channel 17 from.

The pneumatic fiber transport line 11 is associated with the device 12 according to the invention. The device 12 is suitable for detecting any foreign matter, e.g. Pieces of fabric, tapes, cords, pieces of film u. Like. In fiber. According to an advantageous embodiment, the device 12 for detecting foreign parts made of plastic, such as polypropylene tapes, fabrics and films u. in or between fiber flakes, e.g. made of cotton and / or man-made fibers. The plastics are bright, white or transparent.

In the device 12 for detecting foreign substances, the fiber material is transported in an air flow (fiber-air flow D) through a pneumatic fiber transport line 11, which is connected to a (not shown) suction source. As an optical sensor system, above the fiber transport line 11 across the machine width, e.g. 1600 mm, two cameras 13a, 13b, e.g. Diode matrix cameras with polarizing filters, arranged in a housing 14. Below the cameras 13a, 13b (shown only camera 13a), the wall surfaces of the fiber transport line 11 on two transparent areas in the form of two mutually parallel glass panes 17a, 17b (glass window), which form a glass channel 17. Below the fiber transport line 11, a lighting device 18 is provided as a source of polarized light. Above the fiber transport line 11, a further illumination device 43 is arranged as the source of ultraviolet (UV) light. Downstream of the glass channel 17, a blow-out device 19 is assigned to deposit the foreign substances 34 of the fiber transport line 11 detected by the device 12. The fiber air flow D is sucked through the fiber transport line 11 after the blow-out device 19 and fed to further processing.

The camera 13 detects in operation through the glass sheet 17a through the fiber-air flow D. In this case, the glass plate 17a projects into the fiber-air flow D so that the fiber-air flow D on the glass sheet 17a impinges and flows along the glass pane 17a touching under a contact pressure. By the movement of the fiber-air flow D on the one hand largely or completely unwanted deposits on the glass sheet 17a avoided or in the case of minor deposits they are wiped by the fiber-air flow D of the inner surface of the glass sheet 17a and through the channel 11 discharged. In the same way, the fiber air flow D acts on the inner surface of the glass pane 17b.

If unwanted foreign substances 34 are detected by the device 12 in the fiber-air flow D, the blow-out device 19 is actuated, which blows the foreign substances 34 into a suction channel 20.

2, the light of the light source 18 (here a fluorescent tube) via a polarizing filter 28 is converted into polarized light and passes through a glass sheet 17a in the inspection area. This inspection area is formed in this example by a shaft 41 of rectangular cross-section, through which the fiber material 40 is guided past the inspection point. The material conveyor is here from top to bottom. (The embodiment of Figs. 2 and 3 is equally applicable to the embodiment of Fig. 1 with horizontal channel 11.) The glass sheets 17a, 17b are slightly inclined to the material flow D for self-cleaning of the surfaces. The polarized light passes through the inspection area via a second glass pane 17b finally to a camera 13, which is also equipped with a polarizing filter 42 as an analyzer. This blocks all incident unchanged polarized light of the light source 18a, so that a total of a dark image is formed. Further, the inspection room is illuminated by a light source 43 which emits ultraviolet light (here, there are four UV fluorescent tubes). This light source 43 emits no wavelength components in the visible range, so that the camera 13, which is sensitive only in the visible range of the optical spectrum, experiences no modulation. This is achieved by appropriate optical filters in the light source itself (so-called black light) or by additional filters to be placed in front of the light source. Optionally, the camera 13 or the sensor of the camera 13 must be equipped by another filter 44, which blocks UV light, so that it has no sensitivity in the UV wavelength range.

Since the camera 13 with the analyzer 42 is not sensitive to both the polarized light and the UV light, it will normally pick up a dark image. If fiber material 40 is now located in the inspection space, it is irradiated by the polarized light and illuminated by the UV light. The polarized light is not changed by the fiber material 40, and it remains with the dark image. Also, the UV light is not changed by the fiber material 40. UV light reflected back to the camera 13 is not recorded because the camera 13 is not sensitive in this wavelength range. It stays with the dark picture. On the other hand, if there are transmittable extraneous parts 34 (e.g., packaging tapes of PP or films of PE) in the inspection room, they change the polarization state of the polarized light. This light can now pass through the analyzer 42 of the camera 13 and thus provides a modulation, which is registered by the evaluation unit 38 connected to the camera, and e.g. from a downstream separation unit (blower 19, see Figures 1 and 6) is used to eject these foreign parts 34 from the channel 41. In the case of non-transmittable foreign parts (eg dense plastic packaging residues), no polarized light passes through the foreign part to the camera 13. Instead, the irradiated UV light is detected by a fluorescence effect which can be observed in many packaging materials which are provided with optical brighteners Light of visible wavelengths changed. This light can pass only the UV blocking filter 44 and thus generates a modulation of the camera 13, which in turn is registered by the connected evaluation unit 38.

Fig. 3 shows a similar arrangement in which the camera view of 45 required to reduce installation space via a mirror 46 is folded.

For large channel widths, it may be advantageous to distribute a plurality of detection devices according to Fig. 2so over the working width so that each is responsible for only a portion of the channel 41. But again, each section can be realized both detection methods with only one detector and an evaluation.

Fig. 4 shows such an arrangement, from a viewing direction with material conveying direction D perpendicular to the paper plane, in which a plurality of detection devices 47, 47 are arranged side by side to cover the large working width. Each device 47, 47 is again responsible for both the recognition with polarized light as well as for the detection with UV light, each with only one sensor 13. Although the illuminations 18 and 43 are divided into sections in this example, they are realized by a continuous component in each case. Similarly, the evaluation units assigned to the individual sections can also be combined to form an evaluation unit 38.

According to Fig. 5, a holding device 21 is provided, the four Al extruded hollow sections 21a, 21b, 21c and 21d (holding profiles) comprises, which are arranged in the longitudinal direction - over the machine width - parallel to each other and each with their end faces to the both (not shown) frame walls of the machine are attached. On the extruded profile 21a, a fastening screw 22 is shown by way of example. The inner planar surfaces 21, 21, 21 and 21 <I> <V> form part of the inner circumferential surface of the fiber transport line 11 and the channel 41. The surfaces 21 and 21 on the one hand and the surfaces 21st And 21 <IV>, on the other hand, are respectively aligned with each other. The surfaces 21, 21 on the one hand and the surfaces 21 and 21 <IV> on the other hand are arranged parallel to each other. The mutually facing side regions of the extruded profiles 21a to 21d each have a cylinder jacket section-shaped concave surface. Between the four cylinder jacket-section-shaped surfaces and in contact therewith, a housing 23 is arranged, which is rotatable in the direction of the arrows G, H about its longitudinal axis M. The housing 23 comprises a support element 24 made of two Al extrusion hollow profiles 24a, 24b (support profiles), which are each formed in the form of cylinder sections in cross section. The outer contour of the housing 23 is circular. The convexly rounded outer surfaces of the support profiles 24a, 24b are in engagement with the concave rounded cylindrical jacket-section-shaped surfaces of the holding profiles 21a, 21b or 21c, 21d. In the planar chordal surfaces of the support profiles 24a, 24b are each arranged flat glass panes 17a, 17b, wherein the chord surfaces and the outer surfaces of the glass panes 17a, 17b are aligned with each other. The two opposite surfaces thus formed respectively of chord surfaces and glass sheets 17a and 17b form part of the fiber transport channel 11 and of the channel 41 which narrows in the direction of the fiber air flow D. The two opposing surfaces of the glass panes 17a, 17b form a glass channel 17, which also converges conically in the direction of the fiber-air flow D conically. The area formed by the surfaces 21, 21 closes with the surface of the support element 24a formed by the chord surface and the glass pane 17a at an acute and shallow angle α and the surface formed by the surfaces 21, 21 <IV> closes with it the surface of the support profile 24b formed from the chord surface and the glass sheet 17b has an acute and shallow angle α. The conically converging surfaces of the two opposing surfaces each of chord surface and glass sheet 17a and 17b form an angle β.

Below the housing 23 for the glass channel 17, the illumination device 18 (for polarized transmitted light) is present, which has a housing 25 which in guide grooves on the holding profiles 21c, 21 d - extending over the machine width - is mounted. In the interior of the housing 25, two fluorescent tubes 26, 27, e.g. Neon tubes, which extend with their longitudinal axes over the working width of the machine. The housing 25 is an aluminum extruded hollow profile with cooling fins 25a. In the housing 23 for the glass channel 17 facing top surface 25b of the housing 25 are elongated glass sheets 28a, 28b mounted with polarizing filter. The polarization filters (not shown) of the cameras 13a, 13b on the one hand and the polarizing filters (not shown) of the glass panes 28a, 28b on the other hand are arranged at a right angle to one another.

Above the housing 23 for the glass channel 17, the illumination device 43 (for UV incident light) is arranged (see Fig. 1).

The embodiment in FIG. 5 was explained using the example of the horizontal transport channel 11 (FIG. 1). The embodiment is correspondingly applicable to the vertical channel 41 (Figures 2 and 3).

According to FIG. 6, the blow-out device 19 comprises a plurality of blowing nozzles 30a to 30n, to each of which a valve 31a to 31n is assigned. The blowing nozzles 30a to 30n are connected via the valves 31a to 31n to a common compressed air line 32 which is in communication with a compressed air source 33. Denoted at 11 is the fiber transport line which has inlet openings for the blowing nozzles 30a to 30n. The outlet opening for the blown air streams in the channel 20 is shown in Fig. 1. Via a valve control, the valves 31a to 31n are selectively driven, e.g. in the presence of the foreign matter 34, the valve 31d is momentarily opened, so that a sharp air flow at high speed, e.g. 15 to 25 m / sec, exits through the nozzle 30d and blows the foreign body 34 into the channel 20 (see Fig. 1).

According to FIG. 7, the camera 6, an image evaluation device 36 and a valve control 37 for the valves of the blow-out device 7 are connected to an electronic control and regulation device 35. In addition, the cameras 13a, 13b, an image evaluation device 38 and the valve control 39 for the valves 31a to 31n of the blow-out device 19 are connected to the electronic control and regulation device 35.

Referring to Fig. 8, the device of the invention as shown in Fig. 3 is a cleaner 50, e.g. Trützschler CL-C4, downstream. From the last high-speed garnished roller 514, the fiber material is removed by an air flow E (Luftdoffing) and passes as fiber-air flow D in a channel 52 which is approximately U-shaped, one leg in a vertical channel 53 upwards passes. The fiber air mixture D flows through the channel 53 from bottom to top. The channel 53 is associated with the inventive device, as shown in Fig. 3. Following the detection device according to the invention, a blow-out device 19 (see Fig. 1) is present. The freed of foreign parts fiber-air mixture is then fed to further processing. The device according to the invention (camera 13, illuminations 18, 43, deflection mirror 46) are not arranged directly in the delivery area of the opening roller 514.

Referring to Figure 9, the apparatus of the invention, as shown in Figure 3, is a cleaner 54, e.g. Trützschler CL-C1, downstream. From the high-speed garnished roller 55, the fiber material is removed by the air flow E (Luftdoffing) and passes as a fiber-air flow D in an obliquely arranged channel 56, which passes over a curved portion in a vertical channel 53 upwards. The fiber material D flows through the channel 56 and the channel 53 from bottom to top. The channel 53 is - according to FIG. 8 - associated with the device according to the invention, as shown in Fig. 3. After the detection device according to the invention, the blow-out device 19 (see Fig. 8) is arranged, and the fiber material G freed from foreign parts is subsequently supplied for further processing. The device according to the invention (camera 13, illumination device 18, 43, deflecting mirror 46) are not arranged directly in the delivery region of the opening roller 55.

According to FIG. 10, a vertically arranged channel 57 is provided in a housing 58. The arrangement according to Fig. 10 allows the transport of the fiber material from top to bottom through a channel in which it is monitored. The semi-filled arrow, labeled I, represents the downward movement of the fibers conveyed in an air stream. The monitoring of fibers flowing from top to bottom in a channel has proven advantageous.

The opposing parallel side walls 57, 57 are at least partially formed as transparent disks (see Fig. 2) so as to form a transparent channel 62. Lighting means are assigned outside the outer sides of the two side walls 57 <I>, 57 <II>. A first detection device comprises two CCD cameras 59 <I>, 59 <II> (line scanner cameras), which are directed indirectly onto the glass channel 62 with the aid of two tilted mirrors 60 <I> and 60 <II>, the are arranged at an angle. The optical surfaces are slightly offset from each other. On the side of the channel 57 located opposite to the camera 59 <I>, an illumination system 61 <I> is arranged, and on the side of the channel 57 which is opposite to the camera 59 <II>, is an illumination system 61 <II> arranged. As a result of this measure, the material in the glass channel 62 is recognized by the two cameras 59 <I>, 59 <I> <I> from two sides.

The housing 58 <I>, which contains the glass channel 61, the cameras 59 <I>, 59 <II>, the tilted mirrors 60 <I>, 60 <II> and the illumination systems 61 <I>, 61 <II> form a first recognition module 63 <I> in which, in particular, colored foreign material in or between the cotton is recognized.

Below the first recognition module 63 is a second recognition module 63. The cross sections of the channels 57 are the same.

A second detection device comprises a CCD camera 13, which is indirectly directed to the glass channel 64 by means of a tilted mirror 46, which is arranged at an angle. On the side of the channel 57 located opposite to the camera 13, there is disposed an illumination system 18 having polarization filters (see Fig. 2), and on the side of the channel 57 facing the camera, an illumination system 43 for Arranged UV light. The polarized light (transmitted light) and the light reflected by the ultraviolet irradiation (incident light) are detected in common by the one CCD camera 13. Light-transmitted light and incident light are directed from two sides onto the material in the glass channel 64. The housing 58, which contains the glass channel 64, the camera 13, the tilted mirror 46 and the illumination systems 18, 43 form a second recognition module 63, in which in particular lightly colored or transparent plastics in or between the cotton is recognized. Below the second detection module 63 is a separation module 65. The separation module 65 in the housing 58 comprises the blower 19 with a series of nozzles which is associated with a side wall of the channel 57. A collecting tank 20, which is under negative pressure, for the contaminants that have been blown out of the transport stream is associated with that side wall of the channel 57, which lies opposite the row of nozzles.

The inventive device was shown using the example of a cleaner 50, 54 in the spinning preparation. It is equally applicable in the Ginnerei to a Egreniervorrichtung.

Claims (37)

A device for use in spinning preparation or ginning to detect foreign parts (34) of plastic, such as polypropylene tapes, polypropylene fabrics and polypropylene films, in a fiber material stream (D), e.g. of cotton, which device comprises a light source (18) for polarized light for transilluminating the fiber material stream (D) and transmittable foreign parts (34) contained in the fiber material stream (D), which device further comprises a detector device (13; 13a, 13b) for detecting the altered polarized light transmitted through the transmittable foreign parts (34), and which device comprises another ultraviolet light source (43; 431 to 434) for illuminating the fiber material stream (D) and non-transilluminable material contained in the fiber material stream Foreign parts (34), characterized in that the detector means (13; 13a, 13b) is arranged and arranged to detect light converted from the non-transmittable extraneous parts (34) of ultraviolet light to visible light, and to detect both the transilluminable and the transient non-transmittable foreign parts (34) detected and de m fiber material (40) in the fiber material flow (D) differs. 2. Apparatus according to claim 1, characterized in that the detector device (13; 13a, 13b) is designed such that the by the transmittable foreign parts (34) transmitted modified polarized light and the non-transmittable foreign parts (34) and reflected in visible light converted light simultaneously from the detector device (13; 13a, 13b) is detectable. 3. Device according to one of claims 1 or 2, characterized in that the detector device (13; 13a, 13b) comprises an evaluation device (38; 38). 4. Device according to one of claims 1 to 3, characterized in that for covering a working width a plurality of detector means (13a, 13b) are arranged in sections parallel to each other. 5. Device according to one of claims 1 to 4, characterized in that the detector device (13; 13a, 13b) comprises a camera, wherein in order to reduce the installation space, the camera directive (45) by means of mirrors (46) or prisms is foldable. 6. Device according to one of claims 1 to 5, characterized in that it comprises a polarizing filter (42) as an analyzer, and that the analyzer (42) in the light path in front of the detector means (13; 13a, 13b) is arranged. 7. Apparatus according to claim 5 or 6, characterized in that the camera (13; 13a, 13b) has a filter (44) which prevents the passage of ultraviolet light. 8. Device according to one of claims 3 to 7, characterized in that it comprises a glass channel (17), wherein on the evaluation device (38, 38) a separating unit (19) for separating the foreign parts (34) is arranged, which in With respect to the direction of the fiber material flow (D) downstream of the glass channel (17) is arranged. 9. Device according to one of claims 1 to 8, characterized in that the light source (18; 18a; 18b) is designed for polarized light such that the light is linearly polarized. 10. Device according to one of claims 1 to 8, characterized in that the light source (18; 18a; 18b) is designed for polarized light such that the light is circularly polarized. 11. Device according to one of claims 1 to 8, characterized in that the light source (18; 18a; 18b) is designed for polarized light such that the light is elliptically polarized. 12. Device according to one of claims 1 to 11, characterized in that the device comprises a channel (41) and the light source (18; 18a; 18b) for polarized light and the detector device (13; 13a, 13b) on different sides of the Channels (41) are arranged. 13. Apparatus according to claim 12, characterized in that the ultraviolet light source (43; 431 to 434) and the detector means (13; 13a, 13b) are arranged on the same side of the channel (41). 14. Device according to one of claims 12 or 13, characterized in that the device is designed such that the fiber material (40) is pneumatically conveyed through the channel (41). Device according to any one of Claims 12 to 14, characterized in that the device comprises a roller (5, 55), e.g. a beating roller for feeding the fiber material into the channel (41). 16. Device according to one of claims 1 to 15, characterized in that the detector device (13; 13a, 13b) is a line scan camera. 17. Device according to one of claims 1 to 15, characterized in that the detector device (13; 13a, 13b) is a matrix camera. 18. Device according to one of claims 1 to 17, characterized in that the light source (18; 18a; 18b) for polarized light comprises a polarization filter (28). 19. Device according to claim 18, characterized in that the polarization filter (28) is structurally integrated in the light source (18; 18a; 18b) for polarized light. 20. Device according to claim 6 and one of claims 12 to 19, characterized in that the analyzer (42) is arranged between the channel (41) and the detector device (13; 13a, 13b). 21. Device according to claim 20, characterized in that the analyzer (42) is structurally integrated into the detector device (13; 13a, 13b). 22. Device according to one of claims 1 to 21, characterized in that in the beam path between the light source (18; 18a; 18b) for polarized light and the detector device (13; 13a, 13b) and / or between the further light source (43; 431 to 434) for ultraviolet light and the detector means (13; 13a, 13b) light reflecting elements are arranged. 23. The device according to claim 22, characterized in that the light-reflecting elements are mirrors. 24. Device according to one of claims 1 to 21, characterized in that in the beam path between the light source (18; 18a; 18b) for polarized light and the detector device (13; 13a, 13b) and / or between the further light source (43; 431 to 434) for ultraviolet light and the detector means (13; 13a, 13b) light-refracting elements are arranged. 25. The device according to claim 24, characterized in that the light-breaking elements are prisms. 26. The device according to claim 24, characterized in that the light-refracting elements are lenses. 27. Device according to one of claims 8 to 26, characterized in that the evaluation device (38, 38) and the separation unit (19) by a control or regulating device (35) are electrically connected together. 28. Device according to one of claims 3 to 27, characterized in that the evaluation device (38, 38) is designed in such a way that anisotropies of the foreign parts (34), such as a birefringent effect of the foreign parts (34 ), be evaluated. 29. Device according to one of claims 3 to 28, characterized in that the evaluation device (38, 38) is designed such that for detecting the foreign parts (34) a selectively absorbing behavior of the foreign parts (34), such as dichroism of foreign parts (34). 34). 30. Device according to one of claims 3 to 29, characterized in that the evaluation device (38; 38) is designed such that for detecting the foreign parts (34) an optically active behavior of the foreign parts (34), such as rotational dispersion of foreign parts, is evaluated. 31. Device according to one of claims 1 to 30, characterized in that the detector device (13, 13 a, 13 b) is designed such that it is able to distinguish due to their resolution surface-shaped of fibrous foreign parts (34). 32. Device according to one of claims 1 to 31, characterized in that the further light source (43; 431 to 434) is designed for ultraviolet light as a linear light source for illuminating a working width. 33. Device according to one of claims 1 to 31, characterized in that the further light source (43; 431 to 434) for ultraviolet light has a plurality of juxtaposed individual light sources for illuminating a working width. 34. Device according to one of claims 1 to 31, characterized in that the further light source (43; 431 to 434) for ultraviolet light for illuminating a working width comprises a single point-like light source and a projection device which the ultraviolet light of the punctiform light source the working width is projected. 35. Device according to one of claims 1 to 34, characterized in that the further light source (43; 431 to 434) for ultraviolet light comprises a filter which allows only ultraviolet light to pass. 36. Device according to one of claims 12 to 35, characterized in that it is designed such that the fiber material (40) is conveyed from top to bottom through the channel (41). 37. Device according to one of claims 12 to 35, characterized in that it is designed such that the fiber material (40) is conveyed from bottom to top through the channel (41).