EP3510877B1 - Device and method for inspecting rod-shaped items for the tobacco industry - Google Patents

Description

The invention relates to a device in the tobacco processing industry for optically inspecting rod-shaped articles in the tobacco processing industry, the rod-shaped articles each being a combination of a plurality of segments, and the device comprising a conveying element for transversely axial conveying of the rod-shaped articles and the conveying element comprising a plurality of receiving troughs, in which the rod-shaped articles can be received or are received, the device further comprising an image detection device with which the rod-shaped articles arranged in the receiving troughs can be detected or are detected during the transverse-axial conveyance. The invention also relates to a method for optically inspecting rod-shaped articles in the tobacco processing industry, with the rod-shaped articles each being an assembly of several segments and being conveyed transversely axially by a conveying element in a receiving trough of the conveying element.

Rod-shaped articles of the tobacco processing industry, which are a compilation are made up of several segments are known, for example, as multi-segment filters. When assembling the filter segments, errors can occur, for example swapping filter segments, a missing filter segment, an incorrect position or inserting a filter segment with the wrong length. Furthermore, gaps can occur between filter segments or the filter segments can be tilted relative to one another.

In order to detect such errors during production, is from the EP 1 769 689 A1 a device for measuring properties of multi-segment filters or combinations of filter segments in the tobacco processing industry. The multi-segment filter arrangement is illuminated with a line laser. The light reflected on the surface of the filter segments is received using a line camera, and the data recorded by the line camera is evaluated accordingly.

Another device in which multi-segment filters are tested during cross-axial promotion on a conveyor drum is, for example, from DE 10 2009 041 320 A1 famous. The conveyor drum is provided with a lighting device. The multi-segment filters are accommodated in a slotted receptacle, for example a receptacle trough, of this conveying element. A sensor device that is also provided picks up the radiation shining through the multi-segment filter or through the arrangement of a plurality of segments present in the receiving trough. Observation takes place via a mirror, the emitted radiation is collimated using a lens and directed to a CCD camera. In this transmitted light method, filter segments filled with activated carbon are particularly easy to detect.

Out of DE 20 2015 004 790 U1 a device for optically checking articles in the tobacco processing industry is known, which comprises an image acquisition device with at least one image sensor and at least one light source for illuminating the article to be checked. The image capturing device comprises a plurality of image sensors arranged next to one another, for example in one or more rows. Each of the image sensors is assigned a cylindrical lens with a rectangular cross-sectional area, which is designed, for example, as a plano-concave cylindrical lens or as a combination of plano-convex and concave cylindrical lenses.

Out of DE 10 2014 209 000 A1 a device for optically checking the surface of rod-shaped articles in the tobacco processing industry is known. The articles are checked during cross-axial conveyance on a conveyor drum. The device comprises a plurality of light sources, which are switched on one after the other in a predetermined order for a predetermined period of time by means of a control device. DE-A1-10 2016 107 247 discloses the preamble of claim 1.

If the distance between the segments of a rod-shaped article, which is conveyed transversely axially on a conveyor drum, is to be measured with high accuracy, a line camera with a very high resolution would be required in the conventional solutions mentioned above. However, such cameras are complicated to operate and also expensive to purchase. In addition, the segment arrangement would have to be imaged on the line scan camera without distortion or distortion, which requires telecentric optics. With telecentric optics, the light bundles from the observed object area enter the front lens of the objective parallel to the optical axis. For this reason, a telecentric lens is required to have a front lens that is as large as or larger than a maximum size of the object to be viewed. This requirement means, among other things, that telecentric optics are very expensive. In addition, telecentric optics are quite large and heavy, so that the design effort to implement the measurement arrangement is correspondingly complex and expensive. In addition, a large installation space is required, which in practice often leads to problems in the implementation.

The object of the present invention is to provide a device in the tobacco processing industry for optically inspecting rod-shaped articles in the tobacco processing industry and a method for optically inspecting rod-shaped articles in the tobacco processing industry, with which an exact examination of the rod-shaped articles can be carried out with high Resolution can be made, but the design effort should be kept low.

The object is achieved by a device in the tobacco processing industry for optically inspecting rod-shaped articles in the tobacco processing industry, the rod-shaped articles each being a combination of several segments, and the device comprising a conveying element for transversely axial conveying of the rod-shaped articles and the conveying element comprises a plurality of receiving troughs in which the rod-shaped articles can be received or are received, the device further comprising an image capturing device with which the rod-shaped articles arranged in the receiving troughs can be detected or are captured during the transverse axial conveyance, the image capturing device having a camera arrangement comprises a plurality of cameras for image acquisition, and wherein the cameras are synchronized in particular for simultaneous image acquisition and these cameras are arranged next to one another in a direction of longitudinal extension of the receiving troughs each camera of the camera arrangement comprises an entocentric lens and uses this to image an object field, which the rod-shaped articles arranged in the receiving recesses pass through during the transverse axial conveyance, onto an image field, with the image field comprising a central imaging area in which the lens is distortion-free or images at least with a distortion below a predetermined or predeterminable limit value, which is surrounded by an imaging edge area with greater distortion, the cameras in the camera arrangement being arranged in such a way that the central imaging areas of adjacent cameras overlap, the image capturing device also comprising a processing unit , the is set up to calculate the image data recorded by at least two, in particular all, cameras of the camera arrangement in the central imaging areas to form a common image of the camera arrangement.

The device according to aspects of the invention is based on the technical consideration that the conventional effort, especially the use of telecentric optics and the use of a large line camera with a high resolution, can be avoided by using a camera arrangement that has a plurality of individual cameras arranged side by side. The individual images captured by these individual cameras are offset against each other after capture. In this context, it is advantageous if the cameras are synchronized, i.e. the individual images of the cameras are captured at the same point in time. Overall, such a camera arrangement is less expensive than a correspondingly large line scan camera, since the individual cameras can be standard products that are available at a manageable price. Furthermore, it is advantageous that no special optics, such as telecentric optics, but rather conventional entocentric optics can be used. This represents a further considerable cost advantage. The fundamentally disadvantageous property of entocentric optics for the measurement task, namely distortion, for example pincushion-shaped or barrel-shaped distortion, only plays a subordinate role in the camera arrangement according to aspects of the invention. It does not have a negative effect on the measurement. This is achieved by excluding those edge areas of the image area in which the distortion is high from the measurement task. In other words, only those imaging areas of the cameras are used for the measurement task which lie in a central area in which the entocentric optics also image almost without distortion.

Finally, it is extremely advantageous that the device according to aspects the invention does not take up much space. The entocentric optics are not overly large and can be purchased in good quality at a reasonable price. In addition, the object distance can be selected to be relatively small, for example less than 100 mm, 200 mm, 300 mm or less than 500 mm.

The camera arrangement is preferably arranged in such a way that the rod-shaped articles are imaged directly with the entocentric lenses of the individual cameras without further optical elements, such as for example one or more prisms or the like.

The cameras of the camera arrangements are those with a surface sensor (2D image sensor). In particular, no line scan cameras are used. In particular, the cameras of the camera device are synchronized. In other words, in particular, an image is captured simultaneously with all the cameras in the camera arrangement.

In particular, the camera arrangement comprises such a large number of individual cameras that it is possible, viewed as a whole, to image the rod-shaped article completely in the central areas of the cameras. After the captured image data have been combined to form a common image, a complete image of the rod-shaped article is available for subsequent analysis.

The device is developed in particular in that the processing unit is also set up to quantitatively measure at least one gap between two adjacent segments and/or at least one length of a segment of the rod-shaped article.

In addition to a quantitative evaluation, a qualitative evaluation can also be carried out. For example, it is possible to assess the quality of the cut edge of the individual segments. This is advantageously possible because with the camera arrangement of the device according to aspects of the invention a visual inspection is carried out under supervision, i.e. directly from above. The viewing direction is at least approximately perpendicular to a direction of longitudinal extent of the rod-shaped article. In comparison, if an optical test were to take place with a single entocentric lens, the end faces of the individual segments would be visible at least in the outer segments due to the viewing angle becoming flatter in the edge areas. Such a perspective makes a qualitative assessment of the cut edges difficult or imprecise. A quantitative measurement of the gaps between the adjacent segments or a length of the segments of the rod-shaped articles is difficult and imprecise due to the blurred edges. With the device according to aspects of the invention, however, this is possible at significantly lower costs and in a significantly smaller installation space with the same or similar quality and accuracy as is the case when using a telecentric lens.

With regard to the quantitative evaluation, the device is further developed in particular in that the image acquisition device and the processing unit are also set up to measure at least one distance between two adjacent segments oriented in the direction of longitudinal extent of the receiving troughs and/or a length of a segment oriented in this direction of longitudinal extent, in particular with an accuracy of better than 0.1 mm.

For example, the resolution of the cameras of the camera arrangement is selected such that the resolution of the camera is large enough to achieve the desired resolution given the selected object distance and the optics used. For example, the object distance is 200 mm and a maximum object length is also 200 mm. A resolution of the camera is between 8 and 10 thousand pixels, for example. For example, more than 4 cameras are used in the camera arrangement. Furthermore, for example, the camera arrangement comprises 4, 6, 8 or 10 cameras. The device advantageously allows a very precise measurement the width of the individual gaps between the segments and a very precise measurement of the length of the segments of the rod-shaped article.

The device is further developed in particular in that the processing unit is also set up to calibrate the cameras of the camera arrangement by evaluating the image data of adjacent cameras recorded in the overlapping central image areas and determining a displacement vector between the image areas of adjacent cameras.

The displacement vector determined as part of the calibration is applied to the subsequent recordings in order to align them with one another, so that overall, i.e. in the joint image, there is an objectively and realistically correct representation of the rod-shaped article. Of course, this calibration takes place especially for all cameras. It is also possible to repeat the calibration during the measurement operation, for example at regular intervals.

It is also provided in particular that the cameras of the camera arrangement are sensitive in the visible spectral range. For example, the rod-shaped articles are illuminated in overhead light or in transmitted light. Provision is also made in particular for the illumination to be a continuous light or, in particular, a flashing light or the like. In other words, there is no permanent lighting, for example. This requires the flash to be synchronized with the camera equipment. This synchronization is taken over by the processing unit, for example. A corresponding flash light is actuated simultaneously with a trigger of the individual cameras of the camera arrangement. The image acquisition therefore takes place at the moment when the rod-shaped article, which is received in the receiving trough, is illuminated by the flashlight. The flash device is therefore synchronized with the cameras of the camera device. Furthermore, the image acquisition takes place when the rod-shaped article, which is in the Receiving trough is included, is transported through the field of view of the camera assembly. Furthermore, according to a further embodiment, it is provided in particular that the conveying element is a conveying drum on which the rod-shaped articles are conveyed transversely and axially.

The object is also achieved by an arrangement in the tobacco processing industry, comprising a device according to one or more of the aforementioned embodiments, the arrangement also comprising a rolling device and the device for optically inspecting rod-shaped articles in relation to a conveying direction of the rod-shaped articles upstream the rolling device is arranged.

The rolling device comprises, for example, a conveyor drum on which the rod-shaped articles are conveyed transversely and with which the rod-shaped articles are fed to a roller block. The device for optically inspecting the rod-shaped articles is arranged, for example, in such a way that the assembly of the segments is detected directly on the conveyor drum, just before the assembly is rolled into a sheet. In other words, the device for optical testing is therefore arranged immediately before the rolling process.

• einem Vorhandensein eines oder mehrerer Segmente,
• einer Anzahl der in der Zusammenstellung vorhandenen Segmente,
• einer Lage und/oder Art der Segmente, wobei unter der Art eines Segments beispielsweise dessen Typ und Dimension zu verstehen ist,
• einer Größe zumindest einer Lücke zwischen zwei benachbarten Segmenten,
• einer Größe einer Länge zumindest eines Segments und/oder
• einem Vorhandensein und/oder einer Lage eines Blättchens, welches zur Umhüllung der Zusammenstellung der Segmente in einer Rollvorrichtung vorgesehen ist.

According to further aspects, it is provided that with the device for the optical inspection of rod-shaped articles, a set of parameters is obtained which, in particular, completely describes the composition of a plurality of segments. For example, this set of parameters includes information about:

• a presence of one or more segments,
• a number of segments present in the composition,
• a position and/or type of the segments, whereby the type of a segment is to be understood, for example, as its type and dimension,
• a size of at least one gap between two adjacent segments,
• a size a length of at least one segment and/or
• a presence and/or location of a sheet intended to wrap the assembly of segments in a rolling device.

According to a further embodiment, the arrangement is set up to perform process control and/or regulation on the basis of this parameter set. To this end, it is set up, for example, to make an association between a rod-shaped article and a set of parameters. If a rod-shaped article does not meet a predefined quality criterion due to a deviation in one or more parameters from a specified target value, the arrangement is also set up, for example, to eject this rod-shaped article after the rolling process and exclude it from further processing. It is further provided in particular that the parameter set or individual values/parameters are used to readjust and/or regulate the process of assembling the segments. If, for example, the gap between segments is found to be too small, this information can be used to readjust the composition in such a way that the desired target value is maintained in the subsequent compositions.

Furthermore, it is provided in particular that the set of parameters is used within the framework of quality control for the detection of error sources. For example, defective base materials can be identified.

The object is also achieved by a method for optically inspecting rod-shaped articles in the tobacco processing industry, in which the rod-shaped articles are each composed of a plurality of segments and are conveyed transversely by a conveying element in a receiving trough of the conveying element, the rod-shaped articles being conveyed during the transverse axial Promotion with a plurality of Cameras are recorded, these cameras being arranged next to one another in a longitudinal extension direction of the receiving trough, characterized in that the cameras are in particular synchronized and the rod-shaped articles are recorded in particular simultaneously and each camera captures an object field partially encompassing the rod-shaped articles entocentrically or at least approximately entocentrically Image field, the image field comprising a central imaging area in which a lens of the camera images without distortion or at least with a distortion below a specified or specifiable limit value, which is surrounded by an imaging edge area with greater distortion, and the rod-shaped article is imaged in this way is that the central imaging areas of adjacent cameras overlap one another, with the image data recorded by at least two, in particular by all, cameras in the central imaging areas being combined into one same picture will be offset.

The same or similar advantages apply to the method for optically inspecting the rod-shaped articles as have already been mentioned above with regard to the device, so that repetitions are dispensed with shall be.

In particular, it is provided that the image capture takes place with the aid of cameras which include a two-dimensional image sensor. Provision is also made in particular for the images of the rod-shaped articles to be recorded without another optical element being located in the beam path, such as for example one or more prisms or a mirror. In other words, the cameras capture the rod-shaped article directly through their entocentric lenses.

According to an advantageous embodiment, it is provided that at least one intermediate space between two adjacent segments and/or at least one length of a segment of the rod-shaped article is/is quantitatively measured.

It is also provided that the method is also used to examine the rod-shaped articles or the segments qualitatively, for example with regard to the quality of the cut edges.

It is further provided in particular that a width of one of the intermediate spaces oriented in the direction of longitudinal extension of the receiving trough and/or a length of a segment is/are measured, in particular with an accuracy of better than 0.1 mm. The method advantageously allows a very precise measurement of the width of the gaps between the individual segments.

Provision is also made in particular for the cameras to be calibrated by evaluating the image data of neighboring cameras recorded in the overlapping central image areas and determining a displacement vector between the imaging areas of neighboring cameras.

The method is further developed in particular in that the rod-shaped articles are transported on a conveyor drum during the transverse axial conveyance are recorded.

The object is also achieved by a method for controlling and/or regulating a rolling device in an arrangement in the tobacco processing industry. The arrangement comprises a device for optically inspecting rod-shaped articles according to one or more of the aforementioned embodiments and a rolling device. In the rolling device, the assembly of segments is covered with a leaflet. The rod-shaped articles of the tobacco processing industry are inspected according to a method for optically inspecting rod-shaped articles of the tobacco processing industry according to one or more of the aforementioned embodiments. This check takes place upstream of the rolling device, based on a conveying direction of the rod-shaped articles.

The rolling device comprises, for example, a conveyor drum on which the rod-shaped articles are conveyed transversely and with which the rod-shaped articles are fed to a roller block. For example, the inspection occurs while the assembly of segments is directly on the conveyor drum, just before the assembly is rolled into a sheet.

• einem Vorhandensein eines oder mehrerer Segmente,
• einer Anzahl der in der Zusammenstellung vorhandenen Segmente,
• einer Lage und/oder Art der Segmente, wobei unter der Art eines Segments beispielsweise dessen Typ und Dimension zu verstehen ist,
• einer Größe zumindest einer Lücke zwischen zwei benachbarten Segmenten,
• einer Größe einer Länge zumindest eines Segments und/oder
• einem Vorhandensein und/oder einer Lage eines Blättchens, welches zur Umhüllung der Zusammenstellung der Segmente in einer Rollvorrichtung vorgesehen ist.

According to further aspects, it is provided that during the optical inspection of the rod-shaped articles, a set of parameters is obtained which, in particular, completely describes the composition of a plurality of segments. For example, this set of parameters includes information about:

• a presence of one or more segments,
• a number of segments present in the composition,
• a position and/or type of the segments, whereby the type of a segment is to be understood, for example, as its type and dimension,
• a size of at least one gap between two adjacent segments,
• a size a length of at least one segment and/or
• a presence and/or location of a leaflet which for wrapping the assembly of segments in a rolling device.

Process control and/or regulation is carried out, for example, on the basis of this parameter set. For example, an association between a rod-shaped article and a parameter set can be made. If a rod-shaped article does not meet a predefined quality criterion due to a deviation in one or more parameters from a specified target value, this rod-shaped article can be ejected after the rolling process and excluded from further processing. Provision is also made in particular for the parameter set or individual values/parameters to be used in order to readjust and/or regulate the process of assembling the segments. If, for example, the gap between segments is found to be too small, this information can be used to readjust the composition in such a way that the desired target value is maintained in the subsequent compositions. Furthermore, it is provided in particular that the set of parameters is used within the framework of quality control for the detection of error sources. For example, defective base materials can be identified.

Further features of the invention will be apparent from the description of embodiments of the invention taken together with the claims and the accompanying drawings. Embodiments according to the invention can fulfill individual features or a combination of several features.

FIG. 1

schematisch und vereinfacht einen Aufbau gemäß dem Stand der Technik, mit dem eine optische Abbildung eines stabförmigen Artikels aus einer Zusammenstellung aus mehreren Segmenten mit einem entozentrischen Objektiv durchführbar ist,

FIG. 2

ein mit einer Anordnung aus FIG. 1 erhaltenes Bild,

FIG. 3

eine Kameraanordnung mit einer Mehrzahl von Kameras zur Bilderfassung eines stabförmigen Artikels aus einer Zusammenstellung aus mehreren Segmenten in einer Vorrichtung der Tabak verarbeitenden Industrie

FIG. 4

ein Bildfeld einer ersten und einer zweiten Kamera der Kameraanordnung,

FIG. 5

zueinander korrigierte Bildfelder der ersten und der zweiten Kamera der Kameraanordnung,

FIG. 6a

ein mit dieser Kameraanordnung erhaltenes Bild, welches von einer Verarbeitungseinheit errechnet wurde aus den Bilddaten der einzelnen Bilder der Kameras der Kameraanordnung

FIG. 6b

im Vergleich dazu das bereits aus FIG. 2 bekannte Bild und

FIG. 7

eine Vorrichtung der Tabak verarbeitenden Industrie zum optischen Prüfen von stabförmigen Artikeln der Tabak verarbeitenden Industrie, wobei die Vorrichtung eine Fördertrommel zur queraxialen Förderung der stabförmigen Artikel umfasst, die Fördertrommel eine Vielzahl von Aufnahmemulden umfasst, in denen die stabförmigen Artikel aufgenommen sind und ferner eine Bilderfassungsvorrichtung umfasst ist, mit der die in den Aufnahmemulden angeordneten stabförmigen Artikel während der queraxialen Förderung erfasst werden.

The invention is described below without restricting the general inventive concept using exemplary embodiments with reference to the drawings, with express reference being made to the drawings with regard to all details according to the invention that are not explained in more detail in the text. Show it:

FIG. 1

schematically and simplifies a structure according to the prior art, with which an optical imaging of a rod-shaped article from a combination of several segments can be carried out with an entocentric lens,

FIG. 2

one with an arrangement FIG. 1 preserved image,

FIG. 3

a camera arrangement with a plurality of cameras for image acquisition of a rod-shaped article from an assembly of several segments in an apparatus of the tobacco processing industry

FIG. 4

an image field of a first and a second camera of the camera arrangement,

FIG. 5

mutually corrected image fields of the first and the second camera of the camera arrangement,

FIG. 6a

an image obtained with this camera arrangement, which was calculated by a processing unit from the image data of the individual images of the cameras of the camera arrangement

FIG. 6b

compared to that already out FIG. 2 familiar picture and

FIG. 7

a device in the tobacco processing industry for optically inspecting rod-shaped articles in the tobacco processing industry, the device comprising a conveying drum for transversely axial conveying of the rod-shaped articles, the conveying drum comprising a multiplicity of receiving troughs in which the rod-shaped articles are accommodated and further comprising an image acquisition device is, with which the arranged in the receiving troughs rod-shaped articles are detected during the transverse axial conveyance.

In the drawings, elements and/or parts that are the same or of the same type are provided with the same reference numbers, so that they are not presented again in each case.

1 Fig. 12 shows schematically and simplified a prior art optical setup for imaging a rod-shaped article 2 with an entocentric or near entocentric lens 4. For the sake of simplicity, the entocentric lens 4 is represented by a single lens. The rod-shaped article 2 is an assembly of several segments 6a, 6b, 6c, 6d and 6e. The entocentric lens 4 captures the objects in the object space at an aperture angle α. The outer light beams in this angular range fall obliquely into the entrance lens of objective 4 . This means that the outer segments 6a, 6b and 6d and 6e, especially the two outer segments 6a and 6e, are not viewed directly from above, i.e. from a viewing direction perpendicular to a longitudinal axial direction L (shown in a dot-dash line).

2 shows an example and simplifies the resulting image of the rod-shaped article in FIG 1 known arrangement. The images of the segments 6a..6e are denoted by 8a..8e. Apart from the middle segment 6c (see reference number 8c), all segments 8a . This circumstance means that the edges 12 of the segments 6a..6e of the rod-shaped article 2, in the idealized schematic representation of 2 are shown with a solid line, cannot be clearly identified. It is therefore possible with the help of an entocentric optics 4, as exemplified in 1 is shown, it is only possible to measure the distances D1 to D4 between the segments 6a. While distances D2 and D3 may still be detectable with reasonable accuracy, distances D1 and D4 clearly cannot. Furthermore, it is not possible to guarantee the quality of the To detect edges 12 with sufficient accuracy.

This is remedied by the device according to aspects of the invention, the various exemplary embodiments of which are described below. The device includes a conveying element, which later in connection with 7 is explained in more detail. Furthermore, the device comprises an image capturing device with which the rod-shaped articles 2 can be captured or are captured during the transverse axial conveyance on the conveying member.

The image capturing device comprises a camera arrangement 14, as is shown schematically and in simplified form in 3 is shown. The camera assembly 14 includes a plurality of cameras 16a, 16b, 16c, 16d and 16e. Each of the cameras 16a..16e is provided with an entocentric lens 4a..4e. The cameras 16a..16e of the camera arrangement 14 together with their associated entocentric lenses 4a..4e form the image capturing device 18. The image capturing device 18 also includes means, for example a suitable control or regulation, which ensures that the cameras 16a..16e of the Camera arrangement 14 are synchronized. In other words, the cameras 16a . . . 16e are triggered at the same time, ie they capture image data at the same time.

The image capturing device 18 is set up to capture rod-shaped articles 2, which are arranged in receiving troughs of a conveying element, for example a conveying drum, while they are being conveyed transversely. The individual cameras 16a . This longitudinal direction A is in 3 indicated with a dotted line (cf. also 7 ).

The lenses 4a..4e of the cameras 16a..16e of the camera arrangement 14 are entocentric optics or approximately entocentric optics. For the sake of simplicity, the lenses are entocentric 4a..4e each represented by a single lens. Each lens 4a..4e captures an object field and maps this onto the sensor of the associated camera 16a..16e. The viewing angles of the cameras 16a..16e are shown with their respective opening angles α1, α2, α3, α4 and α5. The opening angles α1..α5 are at least approximately the same size. Light incident on the lenses 4a..4e from the opening angles α1..α5 is imaged onto a central imaging area of the sensors of the cameras 16a..16e. The opening angles α1..α5 of the entocentric lenses 4a..4e of the camera arrangement 14 are all small compared to the opening angle α of in 1 shown entocentric lens 4 according to the prior art. The opening angles α1..α5 of the entocentric lenses 4a..4e overlap in the object space. This overlapping area in object space shall be denoted by reference numeral 26'. Light incident from the overlapping area 26′ is recorded by two cameras 16a . The rod-shaped article 2 passes through the object field during the cross-axial conveyance and is recorded by the cameras 16a..16e.

4 FIG. 1 shows an example of an image field 20a of the first camera 16a, as it is imaged on a surface sensor, for example a CMOS sensor, of this camera by the associated lens 4a. The image field 20b of the second camera 16b of the camera arrangement 14 is also shown. Each of the image fields 20a, 20b includes a central imaging area 22a, 22b. Light incident from the object space at the angle α1 in the lens 4a of the first camera 16a is imaged in the central imaging area 22a. This also applies analogously to the other cameras 16b..16e. The respective central imaging areas in the object space shall be denoted by the reference symbols 22a' to 22e'. In these areas, the associated lenses 4a, 4b image without distortion or almost without distortion. At least the distortion of the associated lens 4a, 4b is below a predetermined limit value. This is given, for example, as a percentage of the ideal image. This limit value is, for example, less than 1%, in particular less than 2%, moreover in particular less than 2.5% and moreover in particular less than 5%, moreover in particular the imaging error is less than 7.5%, moreover in particular less than 10% and more particularly less than 15%.

The central imaging area 22a, 22b is surrounded by an imaging edge area 24a, 24b, in which the distortion is greater than in the central imaging area 22a, 22b. In particular, the distortion in the imaging edge area 24a, 24b is above one of the aforementioned limit values. The cameras 16a..16e of the camera arrangement 14 are arranged such that the central imaging areas 22a, 22b of adjacent cameras 16a..16e overlap one another. The overlapping area 26 is the interface between the adjacent central imaging areas 22a, 22b of adjacent cameras 16a..16e.

There is a processing unit in the image capturing device 18 which is set up to calibrate the cameras 16a..16e of the camera arrangement 14 by evaluating the image data of neighboring cameras 16a..16e captured in the overlapping central image areas 22a, 22b. For example, a cross-correlation between the image data of the images from neighboring cameras in the overlapping area 26 is calculated. Such a comparison allows a displacement vector 28 to be calculated, by which the image fields 20a, 20b of the adjacent cameras 16a, 16b are displaced relative to one another. in the in 4 illustrated embodiment, the displacement vector 28 is directed exclusively vertically. If the overlapping area 26 turns out to be wider than desired or narrower than desired, the displacement vector 28 would also include a corresponding horizontal component. A displacement vector 28 for all neighboring cameras 16a..16e of the camera arrangement 14 is calculated.

The processing unit is now set up to process the cameras 16a..16e of the camera arrangement 14 in the central imaging areas 22a, 22b to calculate a common image of the camera arrangement 14.

figure 5 shows the two image fields 20a, 20b corrected by the displacement vector 28, for example of the cameras 16a and 16, the image field 20b of the second camera 16b being shown with a dashed line for clarification. The two central recording areas 22a, 22b are combined, with the image data of one or the other camera being able to be used in the overlapping area 26 as desired.

By appropriate application of the mechanism described above, the individual image fields 20a to 20e, as shown in 3 are shown schematically and in simplified form, gain a complete picture of the rod-shaped article 2. Deviating from the actual execution are in 3 the image fields 20a..20e, and this only for reasons of clarity, not shown overlapping.

As a result of this measurement, an image of the rod-shaped article 2 can be provided, as shown in FIG. 6a by way of example and schematically simplified. This is already off directly below in FIG. 6b 2 known image of the rod-shaped article 2, as can be obtained with a single entocentric lens 4. Advantageously, apparatus in accordance with aspects of the invention provides an image of the rod-shaped article 2 in which both the edges 12, only some of which are numbered for the sake of clarity only, are clearly visible. Consequently, the distances D1..D4 between the individual segments 6a..6e can be determined very precisely by knowing the imaging scale of the lenses 4a..4e from the distances D1'..D4' between the images 8a..8e of the corresponding segments 6a..6e are calculated.

In other words, the device is set up in such a way that gaps 30 (cf. 3 , only some of which are provided with reference symbols for reasons of clarity) between adjacent ones Segments 6a..6e of the rod-shaped article 2 can be measured quantitatively. The same applies to a length of the segments 6a..6e.

The image capturing device 18 is also set up in particular to measure the distances D1..D4 between the segments 6a..6e with an accuracy which is better than 0.1 mm. For this purpose, depending in particular on the recording distance B (object distance), as shown in 3 is indicated, a resolution of the lenses 4a..4e and a resolution of the sensors used in the cameras 16a..16e (number of image points or pixels per unit length) are selected such that the desired resolution is achieved.

7 shows a device 32 of the tobacco processing industry for the optical inspection of rod-shaped articles 2, the rod-shaped articles 2 for reasons of simplification in 7 are not presented as a compilation of several segments. The device 32 comprises a conveying drum 34 as a conveying element, which is shown in sections. On a surface of the conveyor drum 34 there are receiving troughs 36 in which the rod-shaped articles 2 are received in a conveying direction R during their transverse axial conveyance. The conveying direction R corresponds to a direction of rotation of the conveying drum. Above the receiving troughs 36 is the previously described image capturing device 18, of which only a few camera units, each comprising a camera and an entocentric lens, are shown schematically in an exemplary representation. The receiving troughs 36 have a longitudinal extension direction A, which is already in connection with 3 was mentioned and in 7 is also indicated with a dotted line. The direction of longitudinal extension A is oriented at least approximately perpendicular to the conveying direction R. The individual cameras 16a . It is thus possible to check the rod-shaped articles 2 optically during the cross-axial conveyance on the conveying element 34 .

The device 32 also includes a processing unit 38, for example a computer, a workstation or the like, which is set up, among other things, to control and read out the image capturing device 18, to carry out the aforementioned calibration and to calculate the joint image of the camera arrangement 14.

In the context of the invention, features that are marked with "particularly" or "preferably" are to be understood as optional features.

Reference character list

2

rod-shaped article

4, 4a..4e

entocentric lens

6a..6e

segment

8a..8e

Pictures

10

face

12

cut edges

14

camera arrangement

16a..16e

camera

18

image capture device

20a, 20b

image field

22a, 22b, 22a'..22e'

central imaging area

24a, 24b

Image border area

26, 26'

overlap area

28

move vector

30

spaces

32

Device of the tobacco processing industry

34

funding body

36

receiving recesses

38

processing unit

α,α1..α5

opening angle

L

longitudinal axial direction

D1..D4, D1'..D4'

Distance

A

longitudinal direction

R

conveying direction

Claims (11)

1. An apparatus (32) of the tobacco industry for visually inspecting rod-shaped items (2) of the tobacco industry, wherein the rod-shaped items (2) are each an assembly made up of multiple segments (6a..6e), and wherein the apparatus (32) comprises a conveying element (34) for conveying the rod-shaped items (2) in a transverse-axial manner and the conveying element (34) comprises a plurality of receiving troughs (36) in which the rod-shaped items (2) can be or are received, wherein the apparatus (32) additionally comprises an image acquisition device (18) with which the rod-shaped items (2) arranged in the receiving troughs (36) can be or are acquired during the transverse-axial conveying, wherein the image acquisition device (18) comprises a camera arrangement (14) having a plurality of cameras (16a..16e) for image acquisition, and wherein the cameras (16a..16e) are in particular synchronized for simultaneous image acquisition, and wherein each camera (16a..16e) of the camera arrangement (14) comprises an entocentric lens (4a..4e) and, with the latter, an object field, which the rod-shaped items (2) arranged in the receiving troughs (36) run through during the transverse-axial conveying, is imaged onto a field of view (20a, 20b), wherein the field of view (20a, 20b) comprises a central imaging region (22a, 22b) in which the lens (4a..4e) images free of distortion or at least with a distortion below a predefined or predefinable threshold value, which is surrounded by an imaging edge region (24a, 24b) having greater distortion, characterized in that said cameras (16a..16e) are arranged next to one another in a longitudinal extension direction (A) of the receiving troughs (36) and the cameras (16a..16e) are arranged in the camera arrangement (14) in such a manner that the central imaging regions (22a, 22b) of neighboring cameras (16a..16e) overlap one another, wherein the image acquisition device (18) additionally comprises a processing unit (38) which is designed to balance the image data acquired by at least two, in particular all of the, cameras (16a..16e) of the camera arrangement (14) in the central imaging regions (22a, 22b) to produce a common image of the camera arrangement (14).
2. The apparatus (32) of the tobacco industry according to Claim 1, characterized in that the processing unit (38) is additionally configured to quantitatively survey at least one intermediate space (30) between two neighboring segments (6a..6e) and/or at least one length of a segment (6a..6e) of the rod-shaped items (2).
3. The apparatus (32) of the tobacco industry according to Claim 2, characterized in that the image acquisition device (18) and the processing unit (38) are additionally configured to measure at least one distance (D1..D4) between two neighboring segments (6a..6e) oriented in the longitudinal extension direction (A) of the receiving troughs (36) and/or one length of a segment (6a..6e) oriented in said longitudinal extension direction (A), in particular with an accuracy of better than 0.1 mm.
4. The apparatus (32) of the tobacco industry according to any one of Claims 1 to 3, characterized in that the processing unit (38) is additionally designed to calibrate the cameras (16a..16e) of the camera arrangement (14) by evaluating the image data of neighboring cameras (16a..16b) acquired in the central image regions (22a, 22b) overlapping one another and by determining a shift vector (28) between the fields of view (20a, 20b) of neighboring cameras (16a..16e).
5. The apparatus (32) of the tobacco industry according to any one of Claims 1 to 4, characterized in that the conveying element (34) is a conveying drum.
6. An arrangement of the tobacco industry, comprising an apparatus according to any one of Claims 1 to 5 and a rolling device, wherein the apparatus for visually inspecting rod-shaped items (2) is arranged upstream of the rolling device with respect to a conveying direction of the rod-shaped items (2).
7. A method for visually inspecting rod-shaped items (2) of the tobacco industry, wherein the rod-shaped items (2) are each an assembly made up of multiple segments (6a..6e) and are conveyed by a conveying element in a transverse-axial manner in a receiving trough (36) of the conveying element, wherein the rod-shaped items (2) are acquired with a plurality of cameras (16a..16e) during the transverse-axial conveying, wherein said cameras (16a..16e) are arranged next to one another in a longitudinal extension direction (A) of the receiving trough (36), characterized in that the cameras (16a..16e) are in particular synchronized and the rod-shaped items (2) are in particular acquired simultaneously and each camera (16a..16e) images an object field partially comprising the rod-shaped items (2) entocentrically onto a field of view (20a, 20b), wherein the field of view (20a, 20b) comprises a central imaging region (22a, 22b) in which a lens (4) of the camera (16a..16e) images free of distortion or at least with a distortion below a predefined or predefinable threshold value, which is surrounded by an imaging edge region (24a, 24b) having greater distortion, and wherein the rod-shaped item (2) is imaged in such a manner that the central imaging regions (22a, 22b) of neighboring cameras (16a..16e) overlap one another, wherein the image data acquired by at least two, in particular by all, of the cameras (16a..16e) are balanced in the central imaging regions (22a, 22b) to produce a common image.
8. The method according to Claim 7, characterized in that at least one intermediate space (30) between two neighboring segments (6a..6e) and/or at least one length of a segment (6a..6e) of the rod-shaped items (2) is/are quantitatively surveyed.
9. The method according to Claim 8, characterized in that a width of an intermediate space (30) oriented in the longitudinal extension direction (A) of the receiving trough (36) and/or a length of a segment (6a..6e) oriented in the longitudinal extension direction (A) is/are measured, in particular with an accuracy of better than 0.1 mm.
10. The method according to any one of Claims 7 to 9, characterized in that the cameras (16a..16e) are calibrated by evaluating the image data of neighboring cameras (16a..16e) acquired in the central image regions (22a, 22b) overlapping one another and by determining a shift vector (28) between the imaging regions (22a, 22b) of neighboring cameras (16).
11. The method according to any one of Claims 7 to 10, characterized in that the rod-shaped items (2) are acquired during the transverse-axial conveying on a conveying drum.

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