Abstract:
The invention relates to a method for testing cigarette heads, at least one region of a cigarette head being irradiated with light, and light reflected by the cigarette head being received by a detector in such a way that irradiating and received reflected light run at an angle to one another, the irradiated region is imaged on the detector and a signal generated by the detector is evaluated. Such known methods have the disadvantage that they are inaccurate and do not permit exact statements on the state of cigarettes. The invention is therefore based on the problem of improving the testing of cigarettes. It solves this problem by virtue of the fact that, when evaluating, a possible deviation, in particular a distance, of the position of the image of the irradiated region from an expected position of an image of a corresponding region of an ideal cigarette head onto the detector is determined, the deviation being used to determine the distance of the irradiated region from a desired position of this region. The invention also relates to an apparatus for carrying out this method.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for testing cigarette heads, at least one region of a cigarette head being irradiated with light, and light reflected by the cigarette head being received by a detector in such a way that irradiating and received reflected light run at an angle to one another, the irradiated region is imaged on the detector and a signal generated by the detector is evaluated. The invention also relates to an apparatus for testing cigarette heads, having a light source and an optical system for producing at least one region, irradiated with light, on a cigarette head, and having a detector, for receiving light reflected by the cigarette head, which is arranged in such a way that irradiating and received reflected light run at an angle to one another and the irradiated region can be imaged on the detector. 
     A test method or a testing apparatus is known for contactless testing of cigarette heads, in the case of which a straight line is radiated onto a tobacco-end cigarette head. If the cigarette is not properly filled with tobacco, the line no longer appears as a straight line—if it is observed from a different viewing angle—, but as a wavy line or as a broken wavy line. This image is detected by a sensor. Finally, the image points which lie inside and outside a narrow region around an imaginary, theoretical straight line are counted and their ratio is formed. If this ratio exceeds a limiting value, this is formed to indicate that a cigarette is not properly filled. 
     This type of testing has the disadvantage that it is inaccurate and does not permit exact statements on the state of a cigarette. The invention is therefore based on the problem of improving the testing of cigarettes and permitting more accurate statements on the state of a cigarette. 
     SUMMARY OF THE INVENTION 
     For the purpose of solving this problem, the method according to the invention is characterized in that, when evaluating, a possible deviation, in particular a distance, of the position of the image of the irradiated region from an expected position of an image of a corresponding region of an ideal cigarette head on the detector is determined, the deviation being used to determine the distance of the irradiated region from a desired position of this region. Furthermore, the problem is solved by an apparatus according to the invention which is characterized by an evaluation device which evaluates a signal generated by the detector in order to determine a possible deviation, in particular a distance, in the position of the image of the irradiated region from an expected position of an image of a corresponding region of an ideal cigarette head, in order to determine from the deviation the distance of the irradiated region from a desired position of this region. 
     A cigarette head can be measured in a contactless fashion by means of the invention. In this case, it is preferred for the light beam of a laser or another bright light source to be used and focused onto a cigarette head via a lens. One or more image points are thereby illuminated essentially at the test distance. A lens focuses the reflected light on a position-sensitive detector. If the illuminated region is not located in its desired position, this leads to a deviation in the image point on the position-sensitive detector, or to a deviation in the image of the illuminated region with reference to an expected position of the image on the detector. On the basis of the geometrical arrangement of the cigarette head or the desired position of the cigarette head, the direction of incidence of the light and direction of the reflected light, as well as of the distances of these positions from the lens or from the optical system and from the detector, this deviation, which may be expressed as a distance, yields the distance of the irradiated region in relation to a desired position of this region. 
     The invention achieves a very high measuring accuracy. Furthermore, an instantaneous exposure of the cigarette head suffices for determining these distances. Consequently, a cigarette head can be measured as it moves and in a contactless fashion. This permits a high operating speed of the cigarette packaging or cigarette producing machine. 
     It is preferred to irradiate and evaluate a plurality of regions of a cigarette head. It is possible in this way to judge the correct construction, in particular of recess filter or Russian cigarettes and, in particular, to measure the length of a hollow section of a tip sleeve of such cigarettes. Furthermore, the correct, in particular round construction of such tip sleeves can be monitored by irradiating a plurality of points or relatively small regions onto the end region of a tip sleeve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Further preferred embodiments of the invention follow from the subclaims and with the aid of the exemplary embodiments illustrated in the drawing, in which: 
     FIG. 1 shows a testing apparatus according to the invention for testing the heads of a cigarette formation, having a light source arranged directly upstream of a lens-stop system; 
     FIG. 2 shows a further testing apparatus according to the invention, having a glass fibre line for guiding light from a remote light source to a lens-stop system; 
     FIG. 3 shows a further testing apparatus according to the invention, having a glass fibre bundle for guiding light of a light source into the region of the cigarette ends; 
     FIG. 4 shows a stop or arrangement of the glass fibre ends of the glass fibre bundle of FIG. 3, in accordance with a section along the line IV—IV in FIG. 1; 
     FIG. 5 shows the light pattern, yielded by the use of a stop or an arrangement of glass fibres in accordance with FIG. 4, on a 7/6/7 formation of 20 cigarettes, in accordance with a section along the line V—V in FIG. 1; 
     FIG. 5 a  shows the geometrical structure of an image of a correctly constructed cigarette on a detector; 
     FIG. 5 b  shows the image resulting on the detector in the case of a geometrical arrangement in accordance with FIG. 5 a , in the case of a section in accordance with the plane of section Vb—Vb; 
     FIG. 6 a  shows the geometrical structure of an image of a cigarette which is too short on a detector; 
     FIG. 6 b  shows the image resulting on the detector in the case of a geometrical arrangement in accordance with FIG. 6 a , in the case of a section in accordance with the plane of section VIb—VIb; 
     FIG. 7 a  shows the geometrical structure of an image of a cigarette of correct length but defective filling on a detector; 
     FIG. 7 b  shows the image resulting on the detector in the case of a geometrical arrangement in accordance with FIG. 7 a , in the case of a section in accordance with the plane of section VIIb—VIIb; 
     FIG. 8 a  shows the geometrical structure of an image of a recess filter cigarette of correct construction, on a detector; and 
     FIG. 8 b  shows the image resulting on the detector in the case of a geometrical arrangement in accordance with FIG. 8 a , in the case of a section in accordance with the plane of section VIIIb—VIIIb. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a testing apparatus  10  for testing cigarette heads, having a light source in the form of a laser  11 . In addition or alternatively, it is also possible to use other light sources having bright light which is monochromatic or non-monochromatic and non-coherent such as, for example, bright LEDs. The light source can shine permanently or be operated in a pulsed fashion in order to produce individual light flashes. 
     A light beam  12  emanating from the laser  11  strikes a lens-stop system  13  which has a lens  14  and a stop (diaphragm)  15  or mask. This lens-stop system  13  converts the light beam  12  into light  18  irradiating cigarette heads  16  of a cigarette formation  17 . The irradiating light  18  is reflected by the cigarette heads  16 . Located in a direction of reflecting is a detector  19 , for example a CCD camera, that is to say a camera having a CCD chip, comprising a plurality of two-dimensionally arranged CCD elements, for producing a two-dimensional image with a multiplicity of pixels. 
     Reflected light  20  received by the detector  19  is arranged at a non-vanishing angle to the irradiating light  18 , that is to say the light beams incident on the cigarette heads  16  are reflected to the detector  19  in a direction deviating from the direction of incidence. In addition to the CCD chip, the detector  19  also has an optical system  21 , in particular a lens located therein. This optical system  21  serves the purpose of focusing the reflected light beams  20  onto the CCD chip. The detector  19  is connected via a cable  22  to an evaluation device in which the received image or images of the irradiated regions of the cigarette heads  16  are evaluated. 
     The cigarette formation  17  is tested in accordance with FIG. 1 as an overall, three-layer formation. Consequently, the detector  19  also detects the cigarette heads  16  of all cigarettes located inside the cigarette formation  17 . The evaluation device must therefore evaluate an image comprising a number of partial images, specifically  20 , corresponding to the number of cigarettes in the formation  17 . This testing of the cigarette formation  17  preferably takes place on the cigarette turret of a cigarette packaging machine. If a defective cigarette is detected in this testing method, this leads to ejection of the corresponding defective cigarette formation  17 . 
     Furthermore, it is also possible to investigate only a single cigarette. Such testing can also take place in the cigarette magazine of a cigarette packaging machine, in which case it is only individual cigarettes which are ejected, and not an entire cigarette formation  17 . The ejection of individual cigarettes is then performed in accordance with the way described in the German Laid-Open Patent Application DE 36 20 735 A1, in particular with the aid of an apparatus explained there. 
     FIG. 2 shows a further testing apparatus  23 , which corresponds to the testing apparatus  10  illustrated in FIG. 1, with the following exception: the light beam  12  does not pass directly to the lens-stop system  13 , but is firstly guided via an optical system  24 , in particular having a lens  25 . This optical system  24  focuses the light beam  12  onto a glass fibre line  26  which has at its ends a section  27  for entry of the light coming from the optical system  24 , and a section  28  for exit of the light coming from the glass fibre line  26 . The light coming from the exit section  28  passes to the lens-stop system  13 . The testing apparatus  23  corresponds otherwise to the testing apparatus  10  in accordance with FIG. 1, to the description of which reference is hereby made. 
     The glass fibre line  26  serves the purpose of enabling a light source  11  also to be arranged at a different location than in the immediate vicinity of the lens-stop system  13 . This has the advantage that it is possible for some of the components of the testing apparatus  23  to be arranged where enough space is available. Other components, such as the lens-stop system  13 , can then be accommodated in the immediate vicinity of the cigarette or cigarette formation  17 . The detector  19  can be accommodated at a different location as appropriate. For this purpose, the detector  19  is likewise connected optically to the site of the cigarette testing, likewise via a glass fibre line. The reflected light  20  is then focused into an appropriate glass fibre line via a small optical system. This produces further space in the region of the cigarette or cigarette formation to be tested. 
     Alternatively, instead of the stops  15  illustrated in FIGS. 1 and 2, it is also possible to use a hologram in order to produce a structured light pattern on the cigarette heads  16  of the cigarette formation  17 . 
     FIG. 3 shows a further testing apparatus  29 , which likewise has a light source  11 . The light beam  12  emanating from the light source  11  is guided, in a fashion similar to FIG. 2, onto an optical system  24  having a lens  25 . This lens  25  serves to focus the light beam  12  onto a bundle of glass fibre lines, or onto the individual fibres of a glass fibre line. The term glass fibre bundle  30  is used below generically for both variants, that is to say both for a bundle of individual glass fibre lines and for a glass fibre line having a multiplicity of individual glass fibres. 
     The glass fibre bundle  30  likewise has an entry section  31  for the entry of the light coming from the optical system  24 , and an exit section  32  for the exit of the light originating from the glass fibre bundle  30 . An apparatus  33  guides the light coming from the exit section  32  in the direction of the cigarette heads  16 . The apparatus  33  serves either only to hold the exit section  32 , or else only to arrange the fibres or glass fibre lines of the glass fibre bundle  30 , in order to produce a specific structured light pattern on the cigarette heads  16 . This is, in particular, an arrangement in accordance with the way illustrated in FIG. 4, the regions illustrated as relatively large circles respectively illustrating a bundle of glass fibres, while the regions illustrated as relatively small circles illustrate only a few or individual glass fibres. 
     Otherwise, the testing apparatus  29  illustrated in FIG. 3 corresponds to the testing apparatuses  10  and  23 , to which reference is made, illustrated in FIG. 1 or  2 . This holds, in particular, for the embodiment (not illustrated) of an additional glass fibre line from the cigarette heads  16  to the detector  19 , that is to say for transporting the reflected light  20 . 
     FIG. 4 shows the stop  15  in accordance with a section along the line IV—IV in FIG.  1 . This stop  15  has three rows of relatively large openings  34 , and a number of relatively small openings  35  arranged around the openings  34 . This stop produces a structured light pattern on the cigarette heads. Each relatively large opening  34  corresponds to the central region of a cigarette located in a cigarette formation  17 . This opening  34  serves the purpose of illuminating a large portion of the cigarette head, in particular essentially 40% to 90% of the surface of the end face of a cigarette head. This relatively large opening  34  serves the purpose of producing a light spot for testing the tobacco or the filter at the cigarette head  16 . It has a diameter of 5 mm to 6 mm, for example, when the cigarette diameter is 8 mm, that is to say the ratio of the relatively large opening  34  to the cigarette diameter is 5{fraction (6/8)}. Alternatively, the relatively large opening  34  can also be of polygonal or irregular construction. 
     In the example in accordance with FIG. 4, six relatively small circular openings  35  are provided in a fashion arranged circularly and concentrically with reference to the relatively large opening  34 . They are located essentially at a distance from the centre of the relatively large opening  34  which corresponds to the cigarette radius, that is to say at a distance of approximately 4 mm from the centre of the relatively large opening  34  in the case of a cigarette having a diameter of 8 mm. These relatively small openings  35  serve the purpose of illuminating the end face of the cigarette paper or the external cigarette wrapping. This is either the cigarette paper itself, or else a paper-like section surrounding a cigarette filter. 
     Furthermore, however, it can also be a tip sleeve of a recess filter cigarette or a Russian cigarette. A recess filter cigarette is a filter cigarette in which the cigarette filter does not terminate with the cigarette paper, the filter being situated set back instead, with the result that a hollow tip is formed. A Russian cigarette is a similar cigarette, but without a filter, that is to say a filterless cigarette likewise has a hollow tip. The construction of this hollow tip can be tested with the aid of the apparatus according to the invention and the method according to the invention. In particular, it is possible according to the invention to scan and test the contour, that is to say the circular construction of the tip, in particular. However, it is also possible to determine the depth of the tip, specifically owing to the advantageous arrangement of at least one illuminated region of the centre of a cigarette head (specifically through the relatively large opening  34 ) and owing to the arrangement of one or more illuminated regions on the edge of the tip sleeve. A depth measurement is likewise performed using the distance-measuring method described here. 
     However, FIG. 4 also serves the purpose of the explanation, already mentioned above, of the apparatus  33 , specifically of explaining the geometrical arrangement of individual glass fibres of the glass fibre bundle  30  for a testing apparatus  29  in accordance with the exemplary embodiment in accordance with FIG.  3 . Here, a plurality of glass fibres are respectively combined to produce relatively large formations, arranged in three layers, in accordance with the relatively large opening  34 . A smaller number of glass fibres are correspondingly arranged to produce a multiplicity of relatively small formations in accordance with the relatively small opening  35 . Such a bundling or combination of glass fibres serves the purpose of producing a structured light pattern which corresponds to the light pattern produced by a stop  15  in accordance with FIG.  4 . 
     FIG. 5 is an illustration of the light pattern  36  resulting on the cigarette heads  16  of a cigarette formation  17 , in an illustration of a section along the line V—V in FIG.  1 . The light pattern  36  comprises a total of 20 relatively large, circular light spots  37  arranged in three layers, specifically in a 7/6/7 formation. Six relatively small light spots  38  are respectively arranged around these relatively large light spots  37  and are located on the outer wrapping  39  of the cigarette. The relatively large light spots  37  serve as evaluation surfaces for testing the tobacco-end or filter-end ends of the cigarette heads  16 . By contrast, the relatively small light spots  38  serve as evaluation surfaces for the paper ends of the tip sleeves in the case of recess filter cigarettes and/or Russian cigarettes. 
     FIG. 5 a  shows the geometrical structure of light  18  which irradiates a cigarette head  16  and passes as reflected light  20  onto a CCD chip  41  via a lens  40 . The cigarette head  16  is located at its correct position in the position illustrated in FIG. 5 a , and is also correctly constructed. In the case of such a correct cigarette, the result on the CCD chip  41  is a display  42  in accordance with FIG. 5 b  corresponding to a section along the line Vb—Vb in FIG. 5 a . The display  42  shows a plurality of irradiated regions  43 , specifically a relatively large region  44  and six relatively small regions  45  in a concentric arrangement therewith. The circular double line is an imaginary line for orientating and indicating the cigarette wrapping  47 . All regions  43  or  44  and  45  respectively illuminate a multiplicity of CCD elements displayed in small squares. These CCD elements form an image, comprising a multiplicity of pixels, of the cigarette heads or of an entire cigarette formation. 
     The display  42  shown by way of example in FIG. 5 b  is arranged symmetrically with the CCD chip. Furthermore, the relatively small regions  45  are also arranged symmetrically or concentrically with the relatively large region  44 . This symmetry indicates a correctly constructed cigarette of correct length. All images of irradiated regions of a cigarette head  16  are located at their expected position, since the correct cigarette head  16  is located at its desired position. 
     By contrast, FIGS. 6 a  and  6   b  show the display  48  of a cigarette which is constructed too short by the length A. The display  48  corresponds essentially to the display  42 . It is however, located in a different position, that is to say the regions  43  or  44  and  45  of the display  42  from FIG. 5 b , specifically the images of the irradiated regions of tobacco and cigarette wrapping are no longer situated in the middle of the CCD chip  41 , but are displaced upwards by comparison with the display  42  from FIG. 5 b . This deviation, that is to say displacement, in particular the distance of this displacement is detected according to the invention by the evaluation device connected to the CCD chip. A desired position of these regions at the distance of the irradiated regions can then be determined from this deviation. 
     FIGS. 7 a  and  7   b  correspondingly show the resulting display  49  of a cigarette of correct length and having a defective filling. As shown in FIG. 7 a , at the cigarette head  16  the cigarette is not filled with tobacco  50  up to the end of the cigarette wrapping  47 . This defective filling changes the display  49  by comparison with the displays  42  and  48  from FIGS. 5 b  and  6   b , respectively. To be precise, the relatively large region  44  of FIG. 7 b  is now no longer arranged concentrically with the relatively small regions  45 . The images of the irradiated regions, that is to say the relatively small and relatively large regions  45  and  44 , are now no longer arranged symmetrically relative to one another. It is thereby possible to infer a defective cigarette. The depth of the hole, that is to say the absence of tobacco, can be concluded from the deviation of the relatively large region  44 , that is to say from the displacement of this region by comparison with the display in FIG. 5 b . The evaluation is performed in such a way that a cigarette is detected as defective in the case of overshooting predetermined limiting values of the deviation, or in the case of asymmetries, and this leads to the ejection of the cigarette or of the cigarette group containing this cigarette. 
     Finally, FIGS. 8 a  and  8   b  show a recess filter cigarette  51  of correct construction. This recess filter cigarette  51  has a hollow tip  50  and a recessed filter  53 . The centrally irradiated region of the recessed filter  53  is imaged as a relatively large region  44  on the CCD chip. By contrast, the relatively small regions  45 , which result from illumination of the tip at six sites, do not form at sites situated concentrically with the relatively large region  44 . This asymmetry of relatively small and relatively large regions  44  and  45  is a normal phenomenon in the case of recess filter cigarettes, but also in the case of Russian cigarettes, and is taken into account when evaluating the display  54  of the evaluation device. 
     A deviation in the display  54  from this expected position shown in FIG. 8 b  results in the case of defectively constructed recess filter cigarettes and/or Russian cigarettes. Such a deviation can likewise be tolerated within specific limiting values. Only upon overshooting of predetermined limiting values is the corresponding cigarette or an entire cigarette formation ejected. 
     In the case of a variant which is not illustrated, two of the previously explained testing apparatuses are provided at both ends of the cigarettes. It is possible in this way to detect the correct construction of a correctly constructed cigarette even in the case of an axial displacement thereof, since the overall length of a cigarette can be inferred on the basis of the determined distance of an end of the cigarette from its desired position at either end, respectively. It is thereby possible advantageously to prevent the ejection of inherently correct cigarettes which are, however, slightly displaced axially. 
     The invention opens up a multiplicity of possibilities in testing cigarette heads, with the result that it is possible to detect not only defective tobacco locations, but also the depth of tips in the case of recess filter cigarettes and/or Russian cigarettes, as well as the construction of the tip itself, that is to say whether the latter is really circular or deformed. Finally, the invention can also be used to determine the length of a cigarette exactly. 
     LIST OF REFERENCE SYMBOLS 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 10 
                 Testing apparatus 
               
               
                   
                 11 
                 Laser 
               
               
                   
                 12 
                 Light beam 
               
               
                   
                 13 
                 Lens-stop system 
               
               
                   
                 14 
                 Lens 
               
               
                   
                 15 
                 Stop 
               
               
                   
                 16 
                 Cigarette head 
               
               
                   
                 17 
                 Cigarette formation 
               
               
                   
                 18 
                 Irradiating light 
               
               
                   
                 19 
                 Detector 
               
               
                   
                 20 
                 Reflected light 
               
               
                   
                 21 
                 Optical system 
               
               
                   
                 22 
                 Cable 
               
               
                   
                 23 
                 Testing apparatus 
               
               
                   
                 24 
                 Optical system 
               
               
                   
                 25 
                 Lens 
               
               
                   
                 26 
                 Glass fibre line 
               
               
                   
                 27 
                 Entry section 
               
               
                   
                 28 
                 Exit section 
               
               
                   
                 29 
                 Testing apparatus 
               
               
                   
                 30 
                 Glass fibre bundle 
               
               
                   
                 31 
                 Entry section 
               
               
                   
                 32 
                 Exit section 
               
               
                   
                 33 
                 Apparatus 
               
               
                   
                 34 
                 Relatively large opening 
               
               
                   
                 35 
                 Relatively small opening 
               
               
                   
                 36 
                 Light pattern 
               
               
                   
                 37 
                 Relatively large light spot 
               
               
                   
                 38 
                 Relatively small light spot 
               
               
                   
                 39 
                 Outer wrapping 
               
               
                   
                 40 
                 Lens 
               
               
                   
                 41 
                 CCD chip 
               
               
                   
                 42 
                 Display 
               
               
                   
                 43 
                 Region 
               
               
                   
                 44 
                 Relatively large region 
               
               
                   
                 45 
                 Relatively small region 
               
               
                   
                 46 
                 Circular double line 
               
               
                   
                 47 
                 Cigarette wrapping 
               
               
                   
                 48 
                 Display 
               
               
                   
                 49 
                 Display 
               
               
                   
                 50 
                 Tobacco 
               
               
                   
                 51 
                 Recess filter cigarette 
               
               
                   
                 52 
                 Hollow tip 
               
               
                   
                 53 
                 Recessed filter 
               
               
                   
                 54 
                 Image 
               
               
                   
                 A 
                 Length