WO2007006702A1

WO2007006702A1 - Device for detecting the weft threads and position of a transported textile web

Info

Publication number: WO2007006702A1
Application number: PCT/EP2006/063893
Authority: WO
Inventors: Karl-Heinz Schmidl
Original assignee: Mahlo Gmbh & Co. Kg
Priority date: 2005-07-12
Filing date: 2006-07-05
Publication date: 2007-01-18
Also published as: DE502006002840D1; EP1924732A1; ATE422576T1; EP1924732B1

Abstract

The invention relates to a device for detecting the weft threads and position of a transported textile web (5). Said device comprises an oscillatory weft-thread detection unit (10) and an image-recording unit (20). The device is characterised in that the oscillatory weft-thread detection unit and the image-recording unit are configured as integral components of a compact measuring head assembly (30) that is located on either side of the web. According to the invention, the measuring head assembly comprises a row of illumination units (40), enabling the oscillatory weft-thread detection unit and the image-recording unit to operate both with incident light and with transmitted light and also comprises integrated control and evaluation electronics (50) for operating the oscillatory weft-thread detection unit and the image-recording unit.

Description

Device for weft thread and position detection of a conveyed textile

web

description

The invention relates to a device for weft thread and position detection of a conveyed textile material web, comprising an oscillatory weft yarn detection unit and an image acquisition unit according to the preamble of claim 1.

To detect a weft layer of a woven material web, which is necessary, inter alia, to assess a distortion of the textile fabric, essentially two methods or devices are known from the prior art.

In a first method, described for example in EP 0 262 525 Bl, and a device provided therefor, recourse is made to an oscillatory movement of a slot-shaped diaphragm element which is rotational in sections and executed around a central position. The textile material passing through in front of the panel element is irradiated by a light source located behind it. If the instantaneous angular position of the slit-shaped diaphragm element now coincides with the current position of the weft thread, a minimization of the received light intensity is registered in a photoelement arranged behind the slit-shaped diaphragm. In conjunction with a certain conveying speed of the textile material, this leads to a characteristic light intensity as a function of the instantaneous angular position of the panel element, from which the weft thread position can be determined. According to the teaching of EP 0 262 525 Bl, such an oscillatory measuring method allows a particularly simple and precise position detection of the weft thread, if the oscillatory movement of the slot-shaped aperture element is carried out stepwise in discrete angles. For this purpose, the slot-shaped diaphragm is adjusted by means of a stepping motor in discrete steps up to a maximum angle in the positive direction of rotation with respect to the central position and a maximum angle in the negative direction of rotation with respect to the central position, while the textile Ma moved material under this arrangement. From the now dependent on the discrete angle intensity values, in particular the angular position of certain maxima and minima, the position of the weft threads of the fabric can be determined very quickly. Such a method is particularly well suited for simple weave structures and a higher conveying speed of the textile material. However, in interwoven structures, in particular embroidered patterns, or low-thread goods, a considerable drop in measurement accuracy occurs because the woven structures falsify the measurement signal, in some cases considerably, or at lower product speeds, the peaks in the angle-dependent intensity value distribution on the photoelement become more indistinct and unclear identify.

EP 0 816 554 B1 discloses a method for distortion correction of a material web printed with a pattern or otherwise provided with optically recognizable patterns, in particular woven, knitted or crocheted fabrics. Here, the recognizable on the web pattern is taken by a CCD image capture device, converted into image signals and processed in an image processing device for generating control signals. The control signals are used for a subsequent distortion correction of the web. The CCD image acquisition device can be arranged according to the teaching specified therein both in the transverse direction, as well as in the longitudinal direction to the conveying direction of the web and therefore both for registering a delay, as well as for controlling a repeat of the web. Such a method, or a device provided for carrying out such a method, can be operated at lower goods speeds and used for distortion control of patterned webs and in part also for weft thread recognition.

The above-mentioned oscillatory measuring method for registering the weft yarn layer and said CCD image recognition method thus relate to two different application areas defined by different speeds of goods transport or a non-existent or existing pattern structure of the material web. In the production of textile Webs, however, it often happens that quite differently structured webs are promoted in a transport device, while the conveying speed due to the internal structure of the respective web must be changed. As a result, either the oscillatory measuring method or the CCD image recognition method can not be used or with only insufficient accuracy. The conveyor system or straightening machine must therefore either be retrofitted on a case by case basis, or necessarily have both an oscillatory measuring device and a CCD image recognition device. This is associated with an increased space requirement and requires the attachment of a variety of additional and differently executed fasteners, such as trusses, brackets, racks and the like on a sometimes very tight space. It is understood that such a conversion is associated with a very high cost and often longer downtime of the system or partly not possible at all.

It is therefore an object of the invention to provide a device for weft, courses and structure detection and / or non-contact temperature measurement textile webs, in which the components can be inserted in a simple manner, cost-effective, space-saving and precisely adjusted in a given straightening machine or web conveyor , The device should also make it possible to operate the straightening machine with arbitrary web speeds and at the same time to ensure reliable structural recognition of the web both with regard to the pattern and the fabric structure at all times. In particular, a combined scanning of the web both in terms of weft position, as well as the position of the web should be made possible in total, depending on the requirement both a reflected light and a transmitted light measurement of the sought quality and manufacturing parameters must be made possible.

The object is achieved with a device for weft thread and position detection of a conveyed textile web, comprising an oscillatory weft detection unit and an image acquisition unit with the Features of claim 1. Features of expedient or advantageous embodiments are described in the subclaims.

According to the invention, the device is characterized in that the oscillatory weft detection unit and the image acquisition unit are formed as integral components of a compact measuring head arrangement arranged on one or both sides of the web, wherein the measuring head arrangement comprises a series of lighting units for both reflected light and transmitted light operation of the oscillatory weft detection unit and the image acquisition unit and a control and evaluation electronics integrated into the measuring head arrangement for operating the oscillatory weft yarn detection unit and the image acquisition unit.

Thus, the device for weft and position detection forms a closed installable measuring system, with both the weft position, as well as the fabric position as needed simultaneously or alternately with the oscillatory detection method or image recognition in both a reflected light, and in a transmitted light configuration leaves. All necessary components are summarized at a designated section of the production or conveyor system of the web, with a removal and installation or fitting a variety of individual components avoided and the installation and implementation costs for the detection device is sustainably reduced.

Conveniently, in one embodiment, the device consists of a measuring head arrangement consisting of two opposite partial measuring heads with the material web passing between the partial measuring heads. In this case, a first part measuring head includes an oscillating or rotating slit diaphragm with a photodetector for the weft detection unit and a second part measuring head a lighting device in transmitted light configuration for the oscillatory slit diaphragm. Furthermore, the second partial measuring head has an image acquisition device, wherein the first partial measuring head contains a lighting device in transmitted light configuration for the image acquisition device. A one-sided arrangement for a reflection operation is possible.

The two partial measuring heads complement each other functionally. The first part of the measuring head is used to scan the web for image acquisition, which is performed in the second part of the measuring head, while the second part of the measuring head for the transillumination of the web for oscillatory weft detection is formed. The image acquisition and the weft detection thus take place in different partial measuring heads and thus do not interfere with each other. For reflected light or reflection mode, light sources are integrated in the respective measuring head.

Ie. the first part measuring head can have an illumination device for incident light operation of the oscillatory weft detection unit, and the second part measuring head can accordingly have a lighting device for an incident light operation of the image detection unit. As a result, both the weft position detection, as well as the image acquisition can be done either in reflected light or transmitted light mode and thus adapted to differently shaped webs in a simple manner.

It is also possible, in another embodiment, to combine the oscillatory weft detection unit and the image acquisition unit together with an illumination unit for incident light operation in the first component measuring head and to provide at least one illumination unit for transmitted light operation of the weft detection unit and / or the image acquisition unit in the second component measuring head. As a result, the lighting unit for the transmitted light operation can be easily exchanged and replaced if necessary.

At least one lighting unit in each of the aforementioned embodiments is designed both for incident light and transmitted light operation in a first variant as a continuously emitting light source, in particular a high-power light source. In a further variant, at least one lighting unit is a light source operating in flash mode. At least one lighting unit is formed in an advantageous development as a monochromatic light source.

In an advantageous embodiment, the image detection unit has a gradient optical system in combination with a mirror device delimiting the overall length of the partial measuring head provided for this purpose. Such optics are very sharp, especially at close range, while the mirror device contributes to the compact shape of the respective partial measuring head.

The measuring head arrangement is expediently encapsulated against adverse environmental influences, in particular atmospheric humidity or high ambient temperatures. Furthermore, in a further advantageous embodiment, the measuring head arrangement can have measuring devices for detecting physical-chemical environmental parameters of the material web, in particular an air humidity sensor and / or a temperature sensor.

The device according to the invention will now be explained in more detail with reference to some exemplary embodiments. For clarity, Figures 1 to 3 are used. The same reference numerals are used for the same or equivalent parts.

In detail shows:

1 shows an exemplary measuring head arrangement in a first embodiment,

2 shows an exemplary measuring head arrangement in a second embodiment,

Fig. 3, the part measuring heads of Fig. 2 seen from the web.

Fig. 1 shows a textile web 5 with an oscillatory weft detection unit 10 on a first side of the web and one on the Both the weft detection unit, as well as the image detection unit are formed as integral parts of a measuring head assembly 30, which is located on both sides of the web. The measuring head arrangement has a number of illumination units 40, which ensure both incident light and transmitted light operation for the weft detection unit or the image acquisition unit. Furthermore, the weft detection unit and the image acquisition unit are each assigned an evaluation electronics 50, which also controls the functional sequence of the illumination devices.

In the embodiment of FIG. 1, the components arranged on one side of the web 5 are combined to form a first part measuring head 60a and the components arranged on the other side of the web to form a second part measuring head 60b and thus form closed compact functional units, which are expediently encapsulated , In this case, the partial measuring head 60a has a slit diaphragm 70 oscillating about an average angular position with a photodetector 75 arranged behind the slit diaphragm. This transmits the angle-dependent light intensity in a measurement voltage, which is processed by the transmitter 50. The second partial measuring head 60b arranged on the other side of the material web 5 has an illumination device 80 which is arranged in a transmitted light configuration with respect to the slit diaphragm 70. The illumination device 80 is a high-power light source, which expediently has an optical system for generating a parallel beam and whose emission direction is oriented perpendicular to the surface of the material web. The illumination device 80 is controlled by an electronic control unit 50 within the second partial measuring head. Furthermore, the second partial measuring head contains an image capture device 90, which is preferably designed as a CCD camera. The image capture device is also controlled by the control electronics 50.

For image formation in transmitted-light mode, an illumination device 100 integrated into the first sub-measuring head 60a is used. In its construction, this substantially corresponds to the illumination device 80. The first sub-measuring head 60a also has an illumination device 110 which interacts with the oscillatory slit 70 in an incident light mode and locally illuminates the material web 5. For an incident light operation of the image capture device 90, a number of illumination devices 115 integrated into the second partial scan head 60 b are provided.

The lighting devices can be designed in the form of the usual types of light sources. Preferably, either intense white light sources in continuous or flash operation or monochromatic light sources are used. The use of monochromatic light makes it possible, via corresponding color filters, to prevent stray light passing, for example, from the illumination device 80 into the image capture device 90 or from the illumination device 100 to the oscillatory weft detection device.

For optimum length limitation of the sub-measuring head 60b, a gradient optical system 127 is provided in optional combination with a mirror unit 130, which transmits the structures of the web 5 to the image-capturing device 90, i. the CCD camera, images. The mirror unit 130 can be designed to be adjustable and can thus be conveniently changed in two angularly perpendicular axes in their angular position. The gradient optics 127 ensures a particularly good resolution of the web structures in the vicinity.

FIG. 2 shows a further exemplary embodiment of the measuring head arrangement 30. In this embodiment, the partial measuring head 60a contains both the weft detection unit 10 and the image acquisition unit 20 with the corresponding components. The partial measuring head 60b has illumination devices for the transmitted light operation of the weft detection unit and the image acquisition unit. In the example shown in FIG. 2, a single light source 120 is provided for this purpose.

The partial measuring head 60a from FIG. 2 also has illumination devices 115a and 115b for incident light operation. The lighting device 115a and 115b are independently activatable. In addition, a sensor 150 for detecting physical or chemical environmental parameters in the vicinity of the web 5 is integrated in the sub-measuring head 60a.

As can be seen from FIG. 2, the image capture device 90 is integrated in the partial measurement head 60a such that its objective is protected by a lens shield 160 against the occurrence of scattered radiation. Thus, for example, the oscillatory weft detection unit 10 can be operated in incident light, while the image detection unit 20 operates in transmitted light mode. Of course, a comparable lens shield is also possible for the slit 70 and can be performed accordingly within the scope of professional practice.

Fig. 3 shows the surface of the partial measuring head 60a of Fig. 2 viewed from the web. The illumination devices 115 have, for optimum illumination of the corresponding area of the material web, a shape that at least partially encloses the openings for the slit 70 and the lens shield 160, respectively. As a result, the detection field of the weft detection unit 10 or the image detection unit 20 can be illuminated to a large extent homogeneously. For this purpose, the illumination devices 115 can have special focusing or diffuser optics with which on the one hand sufficiently clear local illumination of the respective detection field can be achieved with a minimum scattered light component while the detection field is uniformly illuminated.

The device according to the invention for weft thread and position detection of a conveyed textile web allows, by virtue of its described properties, an automatic, independent selection of the optimal measuring method with regard to the tissue properties, depending on the type of material of the web.

Several measuring head configurations are arranged across the width of the material web or it is possible to traverse them over the width of the web. For the surface camera system find CCD or CMOS sensors Application, wherein the illumination for the camera system is effected by pulse-triggered, emitting infrared radiation LEDs.

The resulting camera image is subjected to a configurable filtering, followed by a transformation of the gray-scale image (spatial domain) into the frequency domain by means of a fast Fourier transform (FFT). In a fixed sector in the frequency domain, determined by evaluation angle and minimum or maximum thread frequency, the maximum is sought, which is attributable to the dominant thread structure. The then recognizable angular deviation with respect to the vertical corresponds to the current angular position of the thread structure, wherein the vertical distance to the center corresponds to the frequency of the thread structure. According to the invention, the maximum can be shifted by undersampling to higher frequencies, so that the angular resolution can be increased, so that at a relatively small yarn frequency, the maximum to be sought for determining a Materialbandverzugswertes not in the vicinity of the zero point and is difficult to detect.

With the help of the surface camera system, typical properties are determined which are stored in a so-called recipe memory. For example, the evaluation of the camera image by means of edge filtering with subsequent averaging over the respective image. The resulting value represents a measure of the horizontal edges contained in the image and their characteristics and is therefore a characteristic of the respective type of fabric.

When the measurement is running, the current properties are compared with those in the recipe memory and the recipe with the most common matching properties is determined. If changes are detected here, this is considered a change of the goods and the matching, new recipe is selected. In this way, it is no longer necessary to make a new set up of the system during a web change or the treatment of different fabrics or knitted fabrics, so that production downtime can be avoided. LIST OF REFERENCE NUMBERS

5 textile web

10 oscillatory weft detection unit

20 image capture unit

30 measuring head arrangement

40 lighting unit

50 transmitter

60a first partial measuring head

60b second partial measuring head

70 oscillating slit diaphragm

75 photodetector

80 lighting device

90 image capture device

100 lighting device

110 illumination device for incident light operation

115 Lighting device for reflected light operation

120 light source

127 gradient optics

130 mirror unit

150 measuring sensor

160 lens shield

Claims

claims

1. An apparatus for weft thread and position detection of a conveyed textile web (5) comprising an oscillatory weft yarn detection unit (10) and an image acquisition unit (20), characterized in that the oscillatory weft yarn detection unit and the image acquisition unit are arranged as integral components on both sides of the web compact measuring head arrangement (30) are formed, wherein the measuring head arrangement comprises a series of lighting units (40) for both incident and transmitted light operation of the oscillatory weft detection unit and the image detection unit and an integrated into the measuring head arrangement control and evaluation (50) for operating the oscillatory Weft detection unit and the image acquisition unit has.

2. Apparatus according to claim 1, characterized in that the measuring head arrangement (30) of two opposite part measuring heads (60a, 60b) is formed with the passing between the part measuring web, wherein a first part measuring head (60a) an oscillatory slit (70) with a photodetector (75) for the weft detection unit (10) and a second partial measuring head (60b) has an illumination device (80) in transmitted light configuration for the oscillatory slit diaphragm and the second sub-measuring head comprises an image detection device (90), wherein the first sub-measuring head a lighting device (100) in transmitted light configuration for the image capture device.

3. Apparatus according to claim 1 and 2, characterized in that the first partial measuring head (60a) an illumination device (110) for an incident light operation of the oscillatory weft detection unit and the second sub-measuring head (60b) has a lighting device (115) for an incident-light operation of the image-capturing unit.

4. The device according to claim 1, characterized in that the oscillatory weft yarn detection unit and the image acquisition unit together with a lighting unit for an incident light operation (115) in the first part measuring head (60 a) are united and the second part measuring head (60 b) at least one lighting unit (120) for a transmitted light operation of the weft detection unit and / or the image detection unit.

5. Device according to one of the preceding claims, characterized in that at least one illumination unit (40) is a continuously emitting light source, in particular a high-power light source.

6. Device according to one of claims 1 to 4, characterized in that at least one lighting unit (40) is a light source operating in flash mode.

7. Device according to one of claims 1 to 6, characterized in that at least one illumination unit (40) is a monochromatic light source.

8. Device according to one of the preceding claims, characterized in that the image acquisition unit has a gradient optics (127) in combination with a length of the respective measuring head delimiting mirror device (130).

9. Device according to one of the preceding claims, characterized in that the measuring head assembly against adverse environmental influences, in particular humidity or high ambient temperatures, is encapsulated.

10. Device according to one of the preceding claims, characterized in that the measuring head arrangement measuring means for detecting physical-chemical environmental parameters of the web, in particular an air humidity sensor and / or a temperature sensor (150).