EP1057727B1 - Method and apparatus for inspecting cigarette ends - Google Patents

Description

The invention relates to a method for testing cigarette heads, wherein light radiates in at least two different directions streak-like sections onto the end face of a cigarette head and light reflected from the end face is received and evaluated by a detector. The invention further relates to a device for testing cigarette heads with at least two light sources for illuminating in each case a strip-like section of an end face of a cigarette head from different directions and a detector for receiving light reflected from the end face.

Test methods and test devices for contactless testing of cigarette heads are known, in which one or more straight lines are blasted onto the tobacco-side cigarette head. If the cigarette is not properly filled with tobacco, the line - when viewed from a different angle - no longer appears as a straight line, but as a serpentine line or as a broken serpentine line. This image is captured by a sensor. Finally, the pixels that lie inside and outside a narrow area around an imaginary, theoretical straight line are counted and put in a relationship to one another. If this ratio exceeds a limit, this is to indicate that a cigarette is not properly filled.

This type of testing has the disadvantage that it is inaccurate and does not allow exact statements about the condition of a cigarette.

The invention is therefore based on the problem of improving the testing of cigarettes and of providing more precise information about the condition of a cigarette.

To solve this problem, the method according to the invention is characterized in that during evaluation a distance between two lines resulting from a signal generated by the detector and corresponding to the strip-shaped sections is determined in order to determine the position of the area of the cigarette head irradiated by the sections. Furthermore, the problem is solved by a device according to the invention, which is characterized by an evaluation device for evaluating a signal generated by the detector, which is designed to determine a distance between two lines resulting from the signal and corresponding to the strip-shaped sections in order to determine the Determine the position of the area of the cigarette head irradiated by the sections.

The invention makes use of the knowledge that two light strips converging towards one another and striking a measurement object, namely a cigarette head, provide information about the distance of the measurement object from the measurement arrangement or another fixed point or generally about the position of the measurement object. The distance between the two light strips striking the measurement object provides the desired information about the position of the measurement object.

This type of contactless testing of cigarette heads is particularly suitable for recess filter cigarettes or papyrossi cigarettes, the light strips also being used in these cigarettes at least partially strike the front of the cigarette tube or the mouthpiece tube and the light also reflected from these areas is received and evaluated by the detector. This results in a point-like light spot when the light strip strikes or cuts with the sleeve or mouthpiece sleeve. These point-like light spots provide an orientation point for the end of the cigarette or mouthpiece. With these cigarettes (with a hollow mouthpiece), the light strips striking the tobacco or filter lie behind the end of the mouthpiece. The depth of the mouthpiece sleeve can therefore be determined from a distance between the images of these point-like light spots or light strips on the detector.

The result of the test can be used to generate an error signal if a cigarette does not meet predetermined limit values. Such an error signal leads to the ejection of a cigarette in the cigarette manufacturing or packaging process. A formation of several layers of cigarettes is preferably checked at the same time and the entire formation is ejected if a defective cigarette occurs.

Fig. 1

eine erfindungsgemäße Prüfvorrichtung zum Prüfen von Köpfen einer Zigarettenformation mit einer direkt vor einem Linsen-Blenden-System angeordneten Lichtquelle;

Fig. 2

einen Schnitt entlang der Linie II-II gemäß Fig. 1, der die Stirnflächen von mit Lichtstreifen beleuchteten Zigarettenköpfen einer Zigarettenformation zeigt;

Fig. 3

einen Schnitt entlang der Linie III-III gemäß Fig. 2, die die geometrische Konstruktion der einfallenden Lichtstrahlen zum Erläutern der Abstandsverhältnisse der Lichtstreifen zeigt;

Fig. 4a

das tabakseitige Ende einer korrekt ausgebildeten Zigarette im Längsschnitt;

Fig. 4b

die von zwei Lichtstreifen beleuchtete Stirnfläche des Zigarettenkopfs aus Fig. 4a, wie sie auf einem Detektor abgebildet wird;

Fig. 4c

die von einer Auswerteeinrichtung errechneten Schwerpunktslinien der Abbildungen gemäß Fig. 4b auf dem Detektor;

Fig. 5a

das tabakseitige Ende einer zu kurzen Zigarette im Längsschnitt;

Fig. 5b

die von zwei Lichtstreifen beleuchtete Stirnfläche des Zigarettenkopfs aus Fig. 5a, wie sie auf einem Detektor abgebildet wird;

Fig. 5c

die von einer Auswerteeinrichtung errechneten Schwerpunktslinien der Abbildungen gemäß Fig. 5b auf dem Detektor;

Fig. 6a

das tabakseitige Ende einer Zigarette im Längsschnitt mit einer Fehlstelle im Tabak in Form eines Lochs;

Fig. 6b

die von zwei Lichtstreifen beleuchtete Stirnfläche des Zigarettenkopfs aus Fig. 6a, wie sie auf einem Detektor abgebildet wird;

Fig. 6c

die von einer Auswerteeinrichtung errechneten Schwerpunktslinien der Abbildungen gemäß Fig. 6b auf dem Detektor;

Fig. 7a

den Zigarettenkopf einer korrekt ausgebildeten Rezeßfilterzigaretten im Längsschnitt;

Fig. 7b

die von zwei Lichtstreifen beleuchtete Stirnfläche des Zigarettenkopfs aus Fig. 7a, wie sie auf einem Detektor abgebildet wird;

Fig. 7c

die von einer Auswerteeinrichtung errechneten Schwerpunktslinien der Abbildungen gemäß Fig. 7b auf dem Detektor;

Fig. 8a

einen Zigarettenkopf einer Rezeßfilterzigarette im Längsschnitt mit schräg abgeschnittenem Filter;

Fig. 8b

die von zwei Lichtstreifen beleuchtete Stirnfläche des Zigarettenkopfs aus Fig. 8a, wie sie auf einem Detektor abgebildet wird;

Fig. 8c

die von einer Auswerteeinrichtung errechneten Schwerpunktslinien der Abbildungen gemäß Fig. 8b auf den Detektor.

Further preferred embodiments of the invention result from the subclaims and on the basis of the exemplary embodiments illustrated in the drawing. The drawing shows:

Fig. 1

a test device according to the invention for testing heads of a cigarette formation with a light source arranged directly in front of a lens aperture system;

Fig. 2

a section along the line II-II of Figure 1, showing the end faces of lighted strips of cigarette heads of a cigarette formation.

Fig. 3

a section along the line III-III of Figure 2, showing the geometric construction of the incident light beams to explain the spacing of the light strips.

Fig. 4a

the tobacco side end of a correctly formed cigarette in longitudinal section;

Fig. 4b

the end face of the cigarette head from FIG. 4a illuminated by two light strips, as is imaged on a detector;

Fig. 4c

the center of gravity of the images according to FIG. 4b calculated by an evaluation device on the detector;

Fig. 5a

the tobacco end of a short cigarette in longitudinal section;

Fig. 5b

the end face of the cigarette head from FIG. 5a illuminated by two light strips, as is imaged on a detector;

Fig. 5c

the centroid lines of the images according to FIG. 5b calculated by an evaluation device on the detector;

Fig. 6a

the tobacco end of a cigarette in longitudinal section with a missing part in the tobacco in the form of a hole;

Fig. 6b

the end face of the cigarette head from FIG. 6a illuminated by two light strips, as is imaged on a detector;

Fig. 6c

the centroid lines of the images according to FIG. 6b calculated by an evaluation device on the detector;

Fig. 7a

the cigarette head of a correctly formed recess filter cigarettes in longitudinal section;

Fig. 7b

the end face of the cigarette head from FIG. 7a illuminated by two light strips, as is imaged on a detector;

Fig. 7c

the centroid lines of the images according to FIG. 7b calculated by an evaluation device on the detector;

Fig. 8a

a cigarette head of a recess filter cigarette in longitudinal section with an obliquely cut filter;

Fig. 8b

the end face of the cigarette head from FIG. 8a illuminated by two light strips, as is imaged on a detector;

Fig. 8c

the center of gravity of the images according to FIG. 8b on the detector calculated by an evaluation device.

1 shows a test device 10 for testing a cigarette formation 11 consisting of cigarettes 12 arranged in three layers. The test device 10 has two light sources 13 and 14, each of which preferably comprises a laser, but can also consist of another bright light source, for example an arrangement of bright LEDs. The light emitted is therefore monochromatic and coherent or monochromatic and non-coherent or non-monochromatic and non-coherent. The light sources 13, 14 are either switched on permanently. However, they can also be operated in a pulsed manner so that they produce short flashes of light.

The light beams 15, 16 emanating from the light sources 13, 14 each arrive at an optical system or a lens-aperture system 17, 18 or a hologram, which each of the light beams 15, 16 in three light bands 19, 20, 21 and 22, 23, 24. These light strips 19 to 24 fall on cigarette heads 25 of the cigarettes 12. There, the light strips 19 to 24 have the shape of strip-like sections 26 to 31, as shown in FIG. 2. The end faces of the cigarette heads 25 from FIG. 1 are shown in FIG. 2. The cigarette formation 11 consists of three layers, the two outer layers consisting of seven and the middle layer consisting of six cigarettes. Depending on the position, two strip-like sections 26 and 27 or 28 and 29 or 30 and 31 hit the end faces. The respective upper strip-like sections 26, 28, 30 originate from the light source 13 shown at the top in FIG. 1. The lower strip-like sections 27, 29, 31 accordingly originate from the lower light source 14.

Each strip-like section 26 to 31 covers a wide area of the end face of the respective cigarette heads 25 and in each case somewhat less than half the end face of a cigarette head. Two strip-like sections therefore essentially provide an entire covering of the cigarette end face. This has the advantage that an evaluation of almost the entire end face is possible.

1 also shows a detector 32 which receives light 33 reflected from the end faces. The detector 32 has optics 34 which serve to focus the reflected light 33 onto a sensor. This sensor contained in the detector 32 has a CCD chip which has a multiplicity of two-dimensionally arranged CCD elements. This makes it possible to generate the images of the strip-shaped sections 26 to 31 on the end faces of the cigarette heads on the CCD chip. The individual CCD elements each emit a signal that flows to an evaluation device.

The test device 10 described is preferably located on the cigarette turret of a cigarette packaging machine. However, it can also be arranged in a similar form on the cigarette magazine and there pre-sort or eject individual cigarettes by means of an ejector arranged on the magazine, as described in German published patent application DE 36 20 735 A1. In the case of a test device arranged on the cigarette turret, the detection of a faulty cigarette leads to the ejection of the entire cigarette formation 11. For this purpose, an error signal is generated by the test device that causes the ejector to eject.

FIG. 3 shows a section along the line III-III from FIG. 2, that is to say a longitudinal section through a cigarette head 25. This cigarette head 25 has a filter piece 35, which lies behind the end of the mouthpiece sleeve 36. The incident light strips 20, 23 irradiate the strip-shaped sections 28, 30 at the end of the filter piece 35. In addition, irradiate the light strips 20, 23 also the end face of the mouthpiece sleeve 36 at end sections 37, 38. These sections 28, 29, 37, 38 illustrate the illuminated sections in a recess filter cigarette. A similar picture would result in a papyrosicigarette, but the filter piece 35 is then replaced by tobacco.

The lines shown in broken lines in FIG. 3 show the situation in the case of a cigarette 12 that is too long. In the case of such a defective cigarette, the end face 39 of the filter piece 35 would end offset to the right, as would the end edge of the mouthpiece sleeve 40.

In the case of a properly designed cigarette, the sections 28 and 29 are at a certain distance from one another, as are the distances 37, 38 and the distances of the sections 28 to 37 and 38 and 29 to 38 and 37, respectively Errors of the cigarette heads are closed. Specifically, as shown in Fig. 3, these sections 28, 29, 37, 38 move away from the formation when a cigarette is too long. The section 28 thus shifts to the dashed line 28 'and 29 to the dashed line 29', just like the end sections 37 and 38 to dashed lines 37 'and 38'.

4a shows a longitudinal section through a cigarette head 41 of a filterless cigarette with an end face 42. FIG. 4b shows the image obtained on the detector 32 when the end face 42 is illuminated with two light strips which strike the end face 42 as strip-like sections ,

Two images 43, 44 of strip-like sections meet on the end face 42 and illuminate a multiplicity of pixels 45 represented as points. The circular line 46 shown as a double solid line is an imaginary representation of the cigarette paper 47 surrounding the cigarette head 41. The illustrations 43, 44 have a central section 48 and 49, respectively, which corresponds to the tobacco-side end face areas illuminated by the respective strip-like sections , These middle sections 48, 49 are each delimited by two point-like end sections 50 to 53. These point-like end sections 50 to 53 correspond to bright light spots at the points at which the light strips hit the filter paper.

4c shows the image generated or calculated by an evaluation device. This picture does not necessarily have to be shown. It is sufficient that the data on which this image is based are calculated in order to carry out the invention. A center of gravity line 54, 55 is determined in each case from the middle sections 48, 49. The center of gravity lines 54, 55 are advantageously calculated such that they lie parallel to one another. In addition, the end sections 50 to 53 are combined to form a focal point 56 to 59.

FIG. 5a shows a cigarette that is too short compared to the cigarette shown in FIG. 4a. The cigarette shown in FIG. 5a is shorter by a distance A than that shown in FIG. 4a. As a result, the central sections 48, 49 shown in FIG. 5b are closer together than those shown in FIG. 4b. The same applies to the end sections 50 to 53. This is a consequence of the light strips tapering toward one another with increasing spacing, which lead to the sections being brought together.

The same applies to the center of gravity lines 54, 55 and center of gravity 56 to 59 shown in FIG. 5c. This shift results in a shorter distance C in FIG. 5c than a correspondingly larger section B in FIG. 4c.

6a again shows the cigarette head 41 of a filterless cigarette, in which, however, a piece of the tobacco filling is missing. This leads to a hole 60. In the illustration 43 of an upper light strip on the detector, which detects an upper section of the end face of the cigarette head 41, an irregularity can therefore be seen in the upper middle section 48 in FIG. 6b. The middle section 48 of Figure 43 is namely not essentially aligned horizontally, but falls off obliquely to the side. 6c shows the center of gravity lines 54, 55 calculated therefrom. The center of gravity line 54 shown in FIG. 6c is shifted towards the center of the cigarette in relation to the center of gravity line 54 shown in FIG. 4c.

This is a consequence of the hole 60. Since the lower illustration 44 in FIG. 6b corresponds to that shown in FIG. 4b, the center of gravity line 55 in FIG. 6c is in the same position as in FIG. 4c. The distance between the center of gravity lines 54, 55 no longer corresponds to the desired distance B according to FIG. 4c, but is smaller than this. This suggests a faulty cigarette. A further peculiarity of the representations according to FIGS. 6b and 6c results from the fact that the section 48, which is sloping per se, is converted into a straight center of gravity 54. This computationally forced alignment of the center lines serves to simplify the distance determination of the center lines 54 and 55.

7a shows the cigarette head 61 of a recess filter cigarette with a filter piece 62 and a hollow mouthpiece 63. The light strips striking the cigarette head 61 as strip-like sections are shown as images 64, 65 on the detector 32 according to FIG. 7b. In the case of a cigarette which has been correctly designed in this way, middle sections 66, 67 are displaced toward the cigarette axis. In contrast, the end sections 50 to 53 are in the same position as in FIG. 5b for a completely filled cigarette.

FIG. 7c shows calculated center of gravity lines 68, 69 which, with a proper recess filter cigarette, are at a smaller distance than the distance C shown in FIG. 4c. In addition, the center of gravity 56 to 59 in FIG. 7c are in a different horizontal position than the center of gravity lines 68, 69. This is due to the fact that the light bands or strip-shaped sections striking the cigarette head 61 shift towards the cigarette axis, since these sections are set back in the axial direction, ie are at a greater distance from the test device.

8a again shows a cigarette head 61 of a recess filter cigarette, but the filter 62 is incorrectly designed because it was cut off at an angle. As a result, the middle sections 66, 67 of the illustrations 64, 65 are at a different position in FIG. 8b compared to FIG. 7b. However, end portions 50 through 53 of Figures 64, 65 are in the same position as in Figure 7b. 8b shows that from the illustrations Center of gravity 68, 69 formed in accordance with FIG. 8b, as well as the centers of gravity 56 to 59. The centers of gravity 56 to 59 are not shifted with respect to FIG. 7c, while the center of gravity lines 68 and 69 in FIG. 8b are shifted upwards with respect to FIG. They are also closer together.

The differentiation between focal lines 54, 55 to 68, 69 and focal points 56 to 59 allows one or four reference points to be determined on the edge of the cigarette tube or mouthpiece tube. As a result, statements about past filters or holes in tobacco are even possible in a quantitative manner, i.e. that information about the distances between the end of the cigarette and any holes or the depth of a mouthpiece sleeve for recess filter cigarettes or papyrossi cigarettes can be made. For example, it can be measured whether a mouthpiece sleeve which has a setpoint depth of 5 mm is within tolerance limits of +/- 1 mm.

The test method described and the test device described allow a very high measuring accuracy. Furthermore, a snapshot of a cigarette head or the cigarette heads of a cigarette formation is sufficient to check the length of a cigarette, the depth of a mouthpiece sleeve, the shape of a cigarette head and the filling with tobacco or filter. This allows a cigarette head to be measured in one movement. As a result, in contrast to other known test methods in which, for example, a plunger is pressed onto a cigarette head, a cigarette packaging or production machine can be operated at high speed by this contactless method. The invention therefore opens up a multitude of possibilities when testing cigarette heads.

LIST OF REFERENCE NUMBERS

10

Tester

11

cigarette formation

12

Cigarette

13

light source

14

light source

15

beam of light

16

beam of light

17

Lens-stop system

18

Lens-stop system

19

trunking

20

trunking

21

trunking

22

trunking

23

trunking

24

trunking

25

cigarettes head

26

strip-like section

27

strip-like section

28

strip-like section

28 '

strip-like section

29

strip-like section

29 '

strip-like section

30

strip-like section

31

strip-like section

32

detector

33

reflected light

34

optics

35

filter piece

36

Nose Casing

37

end section

37 '

end section

38

end section

38 '

end section

39

face

40

Nose Casing

41

cigarettes head

42

face

43

Illustration

44

Illustration

45

pixel

46

circular line

47

cigarette paper

48

middle section of the illustration

49

middle section of the illustration

50

end

51

end

52

end

53

end

54

Gravity line

55

Gravity line

56

main emphasis

57

main emphasis

58

main emphasis

59

main emphasis

60

hole

61

cigarettes head

62

filter piece

63

mouthpiece

64

Illustration

65

Illustration

66

middle section of the illustration

67

middle section of the illustration

68

Gravity line

69

Gravity line

A

distance

B

distance

C

distance

Claims (13)

1. Method for inspecting cigarette heads (25, 41, 61), where light radiates in at least two strip-like portions (26-31), which are incident from different directions, onto the end area (39, 42) of a cigarette head (25, 41, 61) and light (33) reflected from the end area (39, 42) is received by a detector (32) and evaluated, characterized in that, in the course of evaluation, a distance (B, C) between two lines (54, 55, 68, 69) which are produced from a signal generated by the detector (32) and correspond to the strip-shaped portions (26-31) is determined in order to establish the position of that region of the cigarette head (25, 41, 61) which is irradiated by the portions (26-31).
2. Method according to Claim 1, characterized in that images of the strip-shaped portions (26-31), said images being received by the detector (32), are subjected to image processing, an area centroid line (54, 55, 68, 69) being determined, in particular calculated, as a corresponding line for each image of a strip-shaped portion (26-31).
3. Method according to Claim 2, characterized in that the area centroid lines (54, 55, 68, 69) are calculated in such a way that they run parallel to one another.
4. Method according to one of Claims 1 to 3, characterized in that an error signal is generated if the distance determined exceeds or falls below a limit value, in particular in order to activate an ejector for ejecting an inspected cigarette (12) or a cigarette formation (11) containing said cigarette (12).
5. Method according to one of Claims 1 to 4, characterized in that the strip-shaped portions (26-31) illuminate essentially the entire end area (39, 42), in particular the end area on the tobacco or filter side, of the cigarette (12).
6. Method according to one of Claims 1 to 5, characterized in that a strip-shaped portion (26-31) covers a plurality of cigarettes, in particular six or seven, arranged next to one another in a layer of a cigarette formation (11) and a number of strip-shaped portions (26-31) corresponding to the number of layers of the cigarette formation (11), in particular three, are radiated from each direction onto the end areas (39, 42).
7. Method according to one of Claims 1 to 6, characterized in that the detector (32) receives light (33) reflected in the axial direction with respect to the cigarette axis and the incident light (19-24) is radiated onto the end area (39, 42) from two directions arranged at identical angles with respect to the cigarette axis.
8. Method according to one of Claims 1 to 7, characterized in that both cigarette heads (25, 41, 61) of a cigarette (12) are inspected and the cigarette length is calculated from the positions obtained.
9. Method according to one of Claims 1 to 8, characterized in that the strip-shaped portions (26-31) partially illuminate the end of the cigarette casing, in particular of the cigarette paper surrounding the cigarette (12), and/or of the tip sleeve (63) of a recessed filter cigarette or Papyrossi cigarette, and the light (33) reflected from this end is received and evaluated.
10. Method according to Claim 9, characterized in that a distance between a centroid (56-59) of an image (50-53) of the illuminated regions (37, 38) of the cigarette casing and a centroid line (54, 55) is calculated in order to infer the depth of a tip sleeve (63) or the depth of a tobacco vacancy (60) and/or a distance between two centroids (56-59) of two images (50-53) of two illuminated regions (37, 38) of the cigarette casing is calculated in order to inspect an embodiment of the cigarette casing, in particular the uniformity thereof.
11. Apparatus for inspecting cigarette heads (25, 41, 61), having at least two light sources (13, 14) for illuminating a respective strip-like portion (26-31) of an end area of a cigarette head (25, 41, 61) from different directions, and having a detector (32) for receiving light (33) reflected from the end area, characterized by an evaluation device for evaluating a signal generated by the detector (32), which evaluation device is designed to determine a distance between two lines (54, 55, 68, 69) which are produced from the signal and correspond to the strip-shaped portions (26-31), in order to establish the position of that region of the cigarette head (25, 41, 61) which is irradiated by the portions (26-31).
12. Apparatus according to Claim 11, characterized by, assigned to a light source (13, 14), in each case a lens-diaphragm system (17, 18) and/or optical system with a hologram for generating the strip-like portions (26-31) in particular a number, in particular three, of strip-like portions (26-31) corresponding to the number of layers of a formation (11), a respective strip-like portion (26-31) being directed at a respective layer.
13. Apparatus according to Claim 11 or 12, characterized by pulsed light sources (13, 14), in particular laser or LED light sources, for generating flashes of light.