EP1176092B1 - Method and apparatus for inspecting cigarette ends - Google Patents

Description

The invention relates to a method for testing cigarette heads, wherein a Cigarette head is irradiated with light and reflected light from the cigarette head is received by a detector, wherein irradiating and receiving reflected light at an angle, in particular triangulation angle, to each other run, and the received light is evaluated to be in the presence of a not to produce a proper signal to reject a cigar. Further The invention relates to a corresponding device for testing Cigarettes heads.

A test method or a test device for non-contact is known Check cigarette heads with a straight line on a tobacco side Cigarette head is blasted. If the cigarette is not working properly with tobacco filled, the line appears - when viewed from another angle becomes - no more than a straight line, but as a snake line or as interrupted Schlangelinie. This image is captured by a sensor. Finally, the pixels that are inside and outside a narrow Area around an imaginary, theoretical straight line lie, counted and in Set relation to each other. If this ratio is a limit This should indicate that a cigarette is not working properly is filled.

This type of checking has the disadvantage that it is inaccurate and not exact Statements about the condition of a cigarette allowed.

From DE 40 00 658 A1 is an optical test method of cigarette ends in which a picture taken by illuminated cigarette ends is known is processed. The brightness values of individual pixels are examined. The Number of pixels with the same brightness is added and added to a coordinate system applied to a histogram. There are three in this histogram characteristic maxima. The number of pixels belonging to one of the maxima becomes counted. If the number of pixels in this maximum within given Limits, the respective cigarette is evaluated as correct and the next one Examined cigarette. This is an irradiation of an area of the Cigarette head, namely its complete face, known after only a criterion, namely the number of "almost black" pixels, evaluated becomes.

From EP 0 843 974 A2 is an optical test method of cigarette ends known, in which the cigarette end by light directed by light guide illuminated and the reflection at different angles by means of two another light guide is led to each one (brightness) sensor. From the Difference of the brightnesses detected by both sensors is on the Correctness of the respective cigarette closed. It will only be one area of the Cigarette end irradiated. Because the reflected light only from one sensor is recorded, only the average brightness of the two reflections related to each other, so the evaluation also after only a criterion takes place.

EP 0 630 586 A2 describes an optical test method of cigarette ends, in which by means of a linear sensor, a brightness curve from the reflection of the lit cigarette end and to a contrast curve and finally a contrast index is processed. The contrast index is with a predetermined reference value and then on the correctness of the closed each cigarette.

The invention is therefore based on the problem of testing To improve cigarettes.

This problem is solved by a method according to claim 1. Furthermore, this problem is solved by a device according to claim 9.

In contrast to the prior art are not linear Selected areas, but area-like. This has one hand the advantage of having larger areas of a cigarette head tested can be. On the other hand, offers a planar scanning the possibility of different methods of investigation or criteria based solely on the areal Training the individual areas are possible, but not with linear formation of the irradiated areas. For example, the size of the surface, its circumference, diameter, Centroid distances, and derived therefrom Magnitudes, such as elongation and compactness of the detector generated Figure of an irradiated area examined. hereby results in an advantageous way the possibility different Define criteria by which to decide whether a cigarette is proper or not-proper is trained. The use of several different Criteria for testing a cigarette thus provides a substantial higher reliability, only non-proper cigarettes weed out and properly trained cigarettes in the Production process. By the combination according to the invention of areal education of irradiated areas and Application of several different criteria in the evaluation The images generated by the detector may be for testing Cigarettes are significantly improved.

Fig. 1

eine Prüfvorrichtung gemäß einem Ausführungsbeispiel der Erfindung zum Prüfen der Köpfe einer Zigarettenformation mit einer Lichtquelle mit Linsen-Blenden-System und einem Detektor;

Fig. 1a

einen Querschnitt durch von Einzellichtquellen ausgesandtem Licht gemäß einem Schnitt entlang der Linie IA-IA in Fig. 1;

Fig. 2

eine in dem Linsen-Blenden-System gemäß Fig. 1 verwendete Blende;

Fig. 3

die Stirnseite einer Zigarettenformation mit jeweils drei bestrahlten Bereichen auf jedem Zigarettenkopf;

Fig. 4

einen Zigarettenkopf, bei dem nur einer von drei sich einander überlappenden Bereichen aktuell bestrahlt ist (schwarz hervorgehoben);

Fig. 5

einen Zigarettenkopf mit drei voneinander beabstandeten bestrahlten Bereichen;

Fig. 6

eine Abbildung eines bestrahlten Bereichs, wie sie von Detektor bei einer nicht-ordnungsgemäßen Zigarette erzeugt wird;

Fig. 7

eine Abbildung eines bestrahlten Bereichs mit nur einer Teilfläche, wie sie vom Detektor bei einer ordnungsgemäßen Zigarette erzeugt wird;

Fig. 8 A bis H

die Auswertung von 25 Zigaretten jeweils anhand eines anderen Kriteriums; und

Fig. 9

die Ergebnisse der Auswertung der verschiedenen Kriterien gemäß Fig. 8.

Preferred embodiments of the invention will become apparent from the dependent claims and with reference to the embodiments illustrated in the drawings. In the drawing show:

Fig. 1

a test device according to an embodiment of the invention for testing the heads of a cigarette formation with a light source with lens aperture system and a detector;

Fig. 1a

a cross section through light emitted by individual light sources according to a section along the line IA-IA in Fig. 1;

Fig. 2

a shutter used in the lens shutter system of Fig. 1;

Fig. 3

the face of a cigarette formation, each with three irradiated areas on each cigarette head;

Fig. 4

a cigarette head in which only one of three overlapping areas is currently irradiated (highlighted in black);

Fig. 5

a cigarette head with three spaced-apart irradiated areas;

Fig. 6

an image of an irradiated area as generated by the detector in the case of an improper cigarette;

Fig. 7

an image of an irradiated area with only a partial area, as it is generated by the detector in a proper cigarette;

Fig. 8 A to H

the evaluation of 25 cigarettes, each based on a different criterion; and

Fig. 9

the results of the evaluation of the various criteria according to FIG. 8.

Fig. 1 shows a test apparatus 10 for testing cigarette heads 11 of a cigarette formation 12. The testing device 10 preferably checks the tobacco-side ends of cigarettes, they However, it can also be used to check filter-side cigarette heads be used.

The test apparatus 10 has a light source 13 which has a plurality of preferably three, individual light sources, in particular laser diodes, having. The individual light sources 14 are each with Light pipes 15 connected, that of the individual light sources 14 outgoing light to a lens aperture system 16, comprising one or more lenses 17 and a diaphragm 18, which are housed in particular in a housing 19.

That of the lens aperture system 16 facing ends of Light pipes 15 outgoing light is substantially parallel aligned and has one shown in Fig. 1a respectively circular cross-section on. That of the individual light sources 14 emitted light thus occurs in a substantially columnar in the lens aperture system 16 a. The light becomes such herein widened by the lenses 17 and formed by the aperture 18, that it is on the opposite side - the exit side - The lens aperture system 16 in turn substantially parallel, columnar structured and uniformly shaped, exit. Through this structuring, different Areas of a cigarette head 11 sharply delineated illuminated become. That a cigarette head 11 is within a one Area delimiting perimeter line evenly with light irradiated. A cigarette head 11 is in several such Divided areas. The areas cover the largest overall Part of the face of a cigarette head.

In an alternative embodiment, the light is on the cigarette heads 11 facing the end of the lens aperture system 16 non-parallel, but converging or diverging out.

From the cigarette heads 11 reflected light is from a Detector 20, in particular a CCD camera received. The Light source 13 and the lens aperture system 16 and the detector 20 are spatially spaced apart at an angle, in particular triangulation angle 21, arranged. To this The way the cigarette heads 11 radiate also run way and the reflected light rays received by the detector 20 in this triangulation angle to each other. The triangulation angle 21 is in the range between 10 ° and 80 °, preferably 20 ° and 60 °, more preferably 20 ° to 30 °, and is preferably essentially 25 °. The detector 20 has an output line 22, which with a (not shown) evaluation unit connected by means of those generated by the detector mappings the irradiated areas are evaluated. The evaluation unit generated in the presence of an improper Cigarette a reject signal. Such a reject signal leads to the rejection of the recognized as defective cigarette or cigarette formation.

The individual light sources 14 are connected to a (not shown) Connected control unit, by means of which the individual light sources 14 can be switched on and off individually. This control unit is so operable that in each case only one light source can be turned on while the rest are turned off stay. That way, those on the cigarette heads selected area are irradiated successively, so that interference between the areas is excluded are. This is particularly advantageous when the areas are so are selected so that they partially overlap. However, if the areas are spaced apart or tangent are selected, the control unit can also be operated in this way be that the individual light sources simultaneously and be turned off. The test takes place in such a way that every area of a cigarette head of a cigarette formation each time only irradiated. This can be during a current one Standstill phase of the cigarette formation take place.

Due to a fast reaction time of the individual light sources However, it is also possible to take the exam during a movement the cigarette formation past the test apparatus 10 over.

Fig. 2 shows the aperture 18 in an enlarged view. The aperture 18 each has a cigarette of the cigarette formation 12 associated opening 23, unhindered by the light can pass through. The arrangement of the openings 23 corresponds the arrangement of the cigarettes within the cigarette formation 12th

3 shows the front side of the cigarette formation 12 with 20 Cigarette heads 11. Each cigarette head 11 are several, namely three, uniform, in particular circular Areas 24 assigned consecutively or simultaneously with Be irradiated light. These areas 24 arise in the same On each cigarette head 11 of the cigarette formation 12 thanks to the plurality of individual light sources 14 and the lens aperture system 16. The emanating from a single light source 14 Light is widened by the lenses 17 and through the Aperture 18 structured such that on each cigarette head the cigarette formation a circular illuminated area 24th is produced. Due to the expansion, there is an overlap the areas 24 of different individual light sources 14 according to the manner shown in Fig. 3. At a lower level at widening, an overlap of the areas can be avoided so that the regions 24 are spaced apart or tangent are arranged together.

Fig. 4 shows a single cigarette head 11 in enlarged Presentation. Of the three areas to be irradiated is only the upper, black area 24 momentarily illuminated, while the other two areas are unlit and only schematic are shown. All three areas 24 are partial arranged overlapping. There will only be one of these areas 24 irradiated with light.

Fig. 5 shows a spaced arrangement of the regions 24 a cigarette head 11. In this arrangement, all three Area are irradiated simultaneously with light. alternative For example, the areas may be arranged to contact each other just touch the edges.

FIG. 6 shows an image 25 generated by the detector 20 from several, namely three sub-areas 26. Due to the angular arrangement of light source 13 and detector 20, in particular in triangulation angle 21, as well as the unevenness of the Surface of a cigarette head 11 is formed in the detector 20th an illustration of the example. Irradiated as shown in Fig. 4 Area 24 with a plurality of partial surfaces 26, between which apparently unlighted areas 27 are. These seemingly unlit areas 27 arise due to shadows, that of the unevenness of the tobacco structure or filter structure be generated. The stronger these bumps are formed are, the larger the seemingly unlit areas or the more unlit areas arise. hereby increases the length of the perimeter of Figure 25 or the total length of all peripheral lines of all partial surfaces 26. The invention has recognized that the length of the circumferential line A measure of the quality of the surface of a cigarette head 11 is. Preferably, the circumferential line is still the length of the connecting lines between the centroids of the faces 26th added, with preferred only the lengths of the connecting lines the largest partial area 26 is taken into account to the other partial areas become.

Fig. 7 shows a cigarette head 11 with a compared to Fig. 6 more uniform surface, i. a surface with less roughness. Figure 25 only exists in this case from a single surface, however, is the circular structure the illuminated area of an irregular border. Although in Fig. 6 and 7, the cigarette heads 11 are circular shown. In fact, however, would be at a complete Illumination of the cigarette heads 11 an elliptical border the cigarette heads are imaged by the detector 20.

Is missing on a cigarette head 11 tobacco, tears an example. In FIG. 7 shows illustration 25 in several, for example, in FIG. 6 shown partial surfaces 26, it lacks parts of Figure 25 or the outline of Figure 25 is less smooth. Around To evaluate these phenomena, a binarization of the received from the detector image signal. The so binarized Illustration then becomes based on the criteria described in more detail below evaluated.

FIGS. 8A to 8 show eight different criteria of the evaluated ones Pictures and their results for every 25 cigarettes. The 25 cigarettes are each plotted on the abscissa, while each determined values of a criterion plotted on the ordinate. The cigarettes are 1 to 10 properly formed cigarettes while the cigarettes 11 to 25 are not properly trained cigarettes.

FIG. 8B illustrates as a criterion the total area of an image 25, possibly taking into account its partial areas 26. If the total area lies above a limit value GR _B , then a cigarette is found to be good. Accordingly, a cigarette is considered bad if the value of the total area is below this limit GR _B.

8F respectively represents the sum of the weights weighted by the partial areas Distances of the centroids of the partial surfaces 26 to the center of gravity of the largest surface 26, without Normalization to the total area according to FIG. 8B. falls below this weighted distance sum a limit GRF will be the respective Cigarette good. Accordingly, a cigarette found to be bad if the limit exceeded GRF becomes.

8A shows a representation, derived from FIG. 8F, of the weighted distance sum of the area centroids of the subareas as explained above, but normalized to the total area as shown in FIG. 8B. If a limit value GR _A for the weighted distance sum with normalization to the respective total area is undercut, a cigarette is found to be good. Accordingly, a cigarette is considered poor if this limit GR _{A is} exceeded.

FIG. 8D illustrates the maximum diameter of an image, which may be measured over a plurality of sub-areas 26. The maximum diameter can also be determined as the diameter of the convex circumference. The convex circumference refers to the curve with the shortest length that encloses all faces of an image. A cigarette is judged to be correct if a limit GR _D for the maximum diameter is undershot. Accordingly, a cigarette is found to be improper if this limit GR _{D is} exceeded.

FIG. 8H similarly illustrates the minimum diameter of an image or through the partial areas of an image or the minimum diameter of the structure enclosed by the convex circumferential line. If the determined minimum diameter exceeds a limit GR _H , a cigarette is deemed to be correct. Accordingly, a cigarette is found to be abnormal if this limit GR _H is exceeded.

Figure 8C illustrates the mean diameter of a map that can be determined as the average of minimum and maximum diameters. Alternatively, this diameter can also be determined as the average of all the diameter resulting with respect to the convex circumferential line. If the mean diameter exceeds a limit GR _C , a cigarette is judged to be correct. Accordingly, a cigarette will be deemed improper if this limit is exceeded.

Fig. 8E illustrates the so-called elongation, which is determined as the ratio of maximum diameter to minimum diameter. If the elongation falls below a threshold GR _E , a cigarette is judged to be proper, and accordingly a cigarette will be deemed to be improper if this limit is exceeded.

Fig. 8G illustrates the so-called compactness of an image. The compactness is a measure that is calculated from the squared length of the circumference, which is divided by the product "4 π total area". In this case, the length of the circumferential line of an image is calculated if necessary, taking into account the lengths of the peripheral lines of the individual partial areas belonging to an image, in particular taking into account the lengths of the connecting lines of the centroids from the largest partial area to the remaining partial areas. If the value of compactness falls below a limit GR _G , a cigarette is judged to be proper, accordingly a cigarette will be deemed to be improper if this limit is exceeded.

In addition to the criteria shown in Figs. 8A to H can the following further criteria are used for the investigation: The length of the perimeter of an image, if necessary considering the lengths of the peripheral lines of partial surfaces of Illustration. Furthermore, the length of the connecting lines is preferred the centroids of the largest partial areas taken into account for the remaining partial areas.

Another criterion is the so-called "fracture" of an image. The fracture is determined by the length of the circumference in the sense of one of the above definitions in proportion to the length of the convex circumference.

Another criterion is the optically measured cigarette length. In particular, two methods are available for this purpose. On the one hand, the cigarette length can be from a triangulation measurement be won. This is useful if that of the Lens iris system directed to the cigarette heads light is formed in parallel. This is a possible deviation, in particular a distance, the position of the image of a irradiated area from an expected position of a Illustration of a corresponding area of an ideal cigarette head determined and from the deviation the length of the tested Cigarette calculated. In another method is from the size or area of an image the length of the cigarette calculated. Prerequisite for this procedure is that that of the lens aperture system 16 on the cigarette heads emitted light non-parallel, but diverging or is converging.

All of the above criteria can be used for each illustration of a irradiate area to be applied. At three irradiated areas each cigarette head would therefore each of the above criteria apply three times. The results can then be averaged, for example become.

FIG. 9 shows a table of the evaluation of the examinations illustrated in FIGS. 8A to H. A dot in this table identifies a cigarette that has been found to be improper by the criterion associated with the corresponding column. A reject signal is generated by the evaluation unit when at least one such point has been assigned to a cigarette, ie has been found to be improper by at least one criterion. The limit values of the criteria GR _A to GR _H are generously selected, ie a cigarette is tended to be more likely to be good than bad.

Of the explained criteria, at least two become one another combined to produce a reject signal if necessary. It but can also be three, four, five, six, seven, eight or more criteria for forming a reject signal with each other be combined. The larger the number combined with each other Criteria is, the higher the degree of reliability when detecting an improper cigarette.

By evaluating images of irradiated cigarette head areas, especially within the area enclosed by the cigarette paper Face of a cigarette head, based on several different criteria can be a very high detection rate not to be achieved with improper cigarettes. By means of The invention therefore considerably improves the testing of cigarettes.

LIST OF REFERENCE NUMBERS

10

Tester

11

cigarettes head

12

cigarette formation

13

light source

14

Single light source

15

light line

16

Lens-stop system

17

lens

18

cover

19

casing

20

detector

21

triangulation

22

output line

23

opening

24

Area

25

Illustration

26

subarea

27

apparently unlit Area

GR _A :

Limit for weighted Distance total with Standardization on total area

GR _B :

Limit for total area

GR _C :

Limit for medium diameter

GR _D :

Limit for maximum diameter

GR _E :

Limit for elongation

GR _F :

Limit for weighted golden handshake

GR _G :

Limit for compactness

GR _H :

Limit for minimum diameter

Claims (11)

1. Method for inspecting cigarette ends (11), a cigarette end (11) being irradiated with light and light reflected by the cigarette end (11) being received by a detector (20), irradiating and received reflected light running at an angle (21) to each other, in particular a triangulation angle, and the received light being evaluated in order to generate a reject signal in the event of an improper cigarette being present, characterized in that, of the cigarette end (11), a plurality of regions (24) of the cigarette end (11) are irradiated one after another with light structured in accordance with these regions (24), in that the irradiated regions (24) are imaged on the detector (20) and in each case an image (25) generated by the detector (20) and associated with the region (24) is evaluated in order to generate the reject signal, and in that the irradiated regions (24) are in each case two-dimensional and each image (25) is evaluated by using a plurality of different criteria.
2. Method according to Claim 1, characterized in that the following are used as criteria:

   the total area of an image (25), if appropriate taking into account a plurality of subareas (26) of the image (25);

   the sum of the distances between the individual area centres of gravity, weighted with the subareas (26), of the subareas from the area of centre of gravity of one of the subareas (26), in particular of the largest subarea (26), with or without normalization to the total area;

   the minimum, maximum and/or average diameter of an image (25);

   the elongation of an image (25), in particular the ratio of maximum to minimum diameter;

   the length of the circumferential line of an image, if appropriate taking into account the lengths of the circumferential lines of the subareas of the image (25);

   the compactness, in particular the ratio of the square of the circumferential line to the total area, and/or

   the fissuring, in particular the ratio of the length of the circumferential line to the length of the convex circumference of a length of the shortest line enclosing all the subareas.
3. Method according to Claim 1 or 2, characterized in that the regions (24) are arranged to some extent intersecting, adjoining one another or spaced apart from one another.
4. Method according to one of the preceding claims, characterized in that the regions (24) are irradiated one after another over time, in particular in the case of partial intersection, or simultaneously, in particular in the case of a mutually adjacent or spaced-apart arrangement.
5. Method according to one of the preceding claims, characterized in that the regions (24) in each case have a uniform, in particular circular, contour.
6. Method according to one of the preceding claims, characterized in that the reject signal is generated if at least one of the criteria is not satisfied, in particular a limiting value (GR_{A - H}) is violated.
7. Method according to one of the preceding claims, characterized in that any deviation, in particular a spacing, of the position of the image (25) of an irradiated region (24) from an expected position of an image (25) of a corresponding region (24) of an ideal cigarette end (11), is determined and the length of the cigarette inspected is calculated from the deviation.
8. Method according to one of the preceding claims, characterized in that the regions (24) are irradiated with non-parallel light, in particular divergent or convergent light, and the length of the corresponding cigarette is calculated from the dimensions, in particular a diameter, of an image.
9. Apparatus for inspecting cigarettes (11), in particular for carrying out a method according to one of Claims 1 to 8, having a light source (13) for irradiating the cigarette end (11), a detector (20) for receiving light reflected from the cigarette end (11), light source (13) and detector (20) being arranged spaced apart from each other and at an angle to each other, in particular a triangulation angle (21), and an evaluation unit for evaluating light received by the detector (20) in order to generate a reject signal when an improper cigarette is detected, characterized in that the light source (13) is provided to generate structured light for irradiating a plurality of regions (24) of the cigarette end (11) one after another, in that the radiating regions (24) can be imaged on the detector (20) and in each case an image (25) generated by the detector (20) and assigned to a region (24) can be evaluated in order to generate the reject signal, in that the light source (13) irradiates the regions (24) two-dimensionally in each case, and the evaluation unit is constructed in such a way that each image (25) can be evaluated by using a plurality of different criteria.
10. Apparatus according to Claims 9, characterized in that the light source (13) has a plurality, in particular three, of individual light sources (14), which are in each case connected to a light line (15) in order to lead light to a lens-aperture stop system (16), which is constructed in such a way as to irradiate the same regions (24) on each cigarette end (11) of a cigarette formation (12) located in the region of the inspection apparatus (10).
11. Apparatus according to Claim 9 or 10, characterized by a control unit for switching the individual light sources (14) on and off cyclically, in particular for switching on only one individual light source (14) in a cyclically alternating manner.

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