GB2176598A

GB2176598A - Method and apparatus for optically testing the ends of rod-shaped articles of the tobacco processing industry

Info

Publication number: GB2176598A
Application number: GB08614234A
Authority: GB
Inventors: Andrzej Radzio
Original assignee: Hauni Werke Koerber and Co KG; Koerber AG
Current assignee: Koerber AG
Priority date: 1985-06-11
Filing date: 1986-06-11
Publication date: 1986-12-31
Also published as: DE3618190A1; JPS61285981A; IT8620496A1; IT1189535B; IT8620496A0; GB8614234D0; GB2176598B

Abstract

Cigarettes 3 whose ends 3a are to be tested for density, the presence or absence of cavities and/or other defects are transported by a peripherally fluted drum-shaped conveyor 1 sideways past the narrow slit-shaped aperture 9 of a stationary diaphragm 11. Radiation from a light source 13 is conveyed to the aperture 9 by a first bundle 16 of fiber optics, and a second bundle 17 of fiber optics conveys reflected radiation from the aperture 9 to a transducer 14 which transmits signals to an evaluating circuit 18. The aperture 9 is surrounded by a surface 7 which contacts the ends 3a of cigarettes 3 during testing of the respective ends to ensure that such cigarette ends are located at an optimum distance from the uniformly distributed ends of the first and second bundles 16, 17 in the aperture 9. The evaluating circuit 18 integrates the signals generated during testing and the integrated signals are modified 24 as a function of the selected speed of the conveyor. <IMAGE>

Description

SPECIFICATION Method and apparatus for optically testing the ends of rod-shaped articles of the tobacco processing industry The present invention relates to testing of cigarettes and analogous rod-shaped articles of the tobacco processing industry, and more particularly to improvements in a method of and in an apparatus for optically testing the ends of such rod-shaped articles.

It is already known to test the ends of plain or filter cigarettes in an apparatus wherein the cigarettes are transported sideways by the peripheral flutes of a rotary drum-shaped conveyor and their ends are caused to reflect radiation which is directed thereagainst by a bundle of fiber optics. The reflected radiation is evaluated and defective cigarettes are segregated from satisfactory or acceptable cigarettes. The purpose of such testing is to detect cigarettes whose ends are overly dense or too soft as well as to detect cigarettes whose ends are formed with cavities as a result of the escape of tobacco shreds.

U.S. Pats. Nos. 3,729,636 (to Merker) and 3,980,567 (to Benini) disclose testing apparatus wherein the articles to be tested are transported sideways and their ends are scanned by a device employing a bundle of fiber optics extending in parallelism with the longitudinal axes of the tested articles. Those ends of the fiber optics which are remote from the path of the articles to be tested are split into two groups or branches one of which receives radiation from a light source and the other of which directs radiation against a signal generating detector. The intensity of reflected light is indicative of the condition (particularly the density) of the ends of the tested articles.The detector generates signals which denote the intensity of reflected light, and such signals are utilized to segregate the articles with defective ends from the remaining (presumably satisfactory or acceptable) articles.

Additional apparatus for testing the ends of cigarettes or analogous rod-shaped articles of the tobacco processing industry are disclosed in U.S. Pat. No. 4,090,794 to Benini, in U.S.

Pat. No. 4,025,770 to Reuland, in U.S. Pat.

No. 4,276,444 to Bald, in U.S. Pat. No.

4,486,098 to Buchegger et al., and in U.S.

Pat. No. 3,993,194 to Reuland. A drawback of patented apparatus is that their reliability is not entirely satisfactory, especially if the articles to be tested are transported at one of several different speeds. Moreover certain presently known testing apparatus can only ascertain the average quality or condition of the ends of entire rows of neighboring rod-shaped articles (see, for example, the aforementioned U.S. Pat. No. 4,486,098 to Buchegger et al.).

Still further, certain presently known testing apparatus cannot accurately scan the entire end of each of a series of rapidly advancing rod-shaped articles, and certain other conventional apparatus cannot generate signals which are indicative of the average condition or quality of each tested end.

One feature of the invention resides in the provision of an apparatus for optically testing the ends of rod-shaped articles (particularly plain or filter cigarettes) of the tobacco processing industry. The apparatus comprises a fluted drum-shaped conveyor or other suitable means for transporting a series of preferably equidistant discrete rod-shaped articles sideways (i.e., at right angles to their respective longitudinal axes) in a predetermined direction so that one end of each article normally advances along a predetermined path, a source of radiation (e.g., a light emitting diode), a diaphragm having a slit-shaped aperture which is adjacent to and extends transversely of the path (preferably radially of the path if the latter is a circular or substantially circular path), a bundle of first fiber opticas for conveying radiation from the source to the aperture, signal generating radiation detector means (such as a photoelectronic transducer), a bundle of second fiber optical for conveying to the detector means radiation which is supplied by the first fiber optics and is reflected by the ends of successive articles during transport of the ends past the aperture, and means for processing the signals which are generated by the detector means. The diaphragm includes an article-containing surface which at least partially surrounds the aperture. The width of the aperture, as considered in the predetermined direction, is preferably a small fraction (most preferably a minute fraction) of the diameter of an article. For example, the width of the aperture can be substantially less than one-fourth of the diameter of an article.

The detector means is preferably designed to generate a plurality of signals during transport of the end of each article past the aperture of the diaphragm, and the processing means preferably includes means for integrating the signals which are generated by the detector means during transport of the end of an article past the aperture. The integrating means can comprise an operational amplifier.

In order to increase the selectivity or improve the sensitivity of detecting missing tobacco, it is proposed according to one embodiment of the invention that the slit-shaped aperture is divided into a plurality of part sensing surfaces between which separate fibre optic bundles terminate. According to a further proposal each fibre optic bundle is associated with a respective evaluating circuit. In this arrangement it is useful to establish the signal stepwise in known manner and supply them to a mean value and limit value evaluation means in which either the machine phase dictates the step or a free running microprocessor system is used.

Such partial evaluation of the cigarette head with the aid of a plurality of individual sensors substantially improves the fault detection.

The transporting means is normally designed to transport the articles at a selected one of a plurality of different speeds (e.g. at a normal high speed and at a lower speed during starting of the machine which turns out or processes the articles). The processing means then preferably includes means for modifying the signals which are generated by the detector means as a function of the selected speed of the tested articles. Such modifying means can comprise signal generating means for directly or indirectly monitoring the speed of the transporting means, and the processing means then further comprises a stage (such as the aforementioned operational amplifier) which receives signals from the monitoring means and from the detector means.

The radiation emitting ends of the bundle of first fiber optics and the radiation receiving ends of the bundle of second fiber optics are preferably uniformly or substantially uniformly distributed at the aperture of the diaphragm.

The radiation source and the detector means are preferably closely adjacent to the aperture, and the diaphragm is preferably formed with a cam face which is located immediately upstream of the aperture, as considered in the predetermined direction, and serves to direct against the article-contacting surface the ends of those rod-shaped articles which extend beyond the path, i.e., of the articles whose axial positions deviate from an optimum axial position. Such cam face preferably merges gradually into the article-contacting surface of the diaphragm.

The apparatus can further comprise means for effecting segregation from the remaining articles of all such articles whose ends reflect excessive and/or insufficient amounts of radiation, i.e., of all such articles whose ends reflect radiation outside of a preselected range which is indicative of satisfactory or acceptable ends of rod-shaped articles.

Another feature of the invention resides in the provision of a method of preferably optically testing the ends of rod-shaped articles of the tobacco processing industry, particularly plain or filter cigarettes. The improved method comprises the steps of transporting a series of discrete articles sideways in a predetermined direction so that one end of each article of the series normally advances along a predetermined path, establishing and maintaining a source of radiation (e.g., a suitable light source), conveying radiation from the source along a plurality of first discrete paths having radiation discharging ends in a transversely extending narrow slit-shaped portion of the predetermined path (e.g., in the aforementioned narrow slit-shaped aperture of a stationary diaphragm) so that the radiation which is conveyed along such first discrete paths is reflected by the ends of successive articles which advance along the predetermined path, conveying reflected radiation from the narrow portion of the predetermined path along a plurality of second discrete paths which have radiation receiving ends in the narrow portion of the predetermined path, generating signals which denote the characteristics of radiation that is conveyed along the second discrete paths, processing the signals, and maintaining the ends of successive articles in immediate proximity of the ends of the first and second discrete paths during travel of the ends of articles past the narrow portion of the predetermined path.

The method preferably further comprises the step of at least substantially uniformly distributing the ends of the first and second discrete paths in the narrow portion of the predetermined path.

The width of the narrow portion of the predetermined path is preferably a small (most preferably a rather minute) fraction of the diameter of an article.

The signal generating step preferably includes generating a plurality of signals during transport of the end of each article past the narrow portion of the predetermined path, and the processing step preferably includes integrating the signals which are generated during transport of the end of an article past the narrow portion of the predetermined path.

The transporting step normally or often involves transporting the articles of the series at a selected one of a plurality of different speeds (e.g., at one of two different speeds), and the processing step then preferably comprises modifying the signals as a function of the selected speed of the articles.

The method preferably further comprises the step of axially shifting (ahead of the narrow portion of the predetermined path, as considered in the predetermined direction) all such rod-shaped articles whose axial positions deviate from a predetermined optimum axial position.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

Figure 1 is a fragmentary partly elevational, partly sectional and partly diagrammatic view of an optical testing apparatus which embodies the present invention; Figure 2 is a fragmentary plan view as seen in the direction of arrow II in Fig. 1; and Figure 3 is a fragmentary sectional view as seen in the direction of arrows from the line Ill-Ill of Fig. 1; Figure 4 is an alternative embodiment of the optical testing apparatus according to the invention, and Figure 5 is a cross-section of the appartus on line V-V of Fig. 4.

The apparatus which is shown in Figs. 1 to 3 comprises a rotary drum-shaped conveyor 1 which has axially parallel peripheral flutes 5 for discrete rod-shaped articles 3 in the form of plain or filter cigarettes which are transported sideways (i.e., at right angles to their respective longitudinal axes) and are attracted to the surfaces surrounding the respective flutes 5 by suction in the ports 2 of the conveyor 1. The suction generating device which communicates with the ports 2 during certain stages of each revolution of the conveyor 1 is not shown in the drawing.

The apparatus further comprises a stationary support 4 for a diaphragm 6 having a narrow slit-shaped aperture 9 which extends radially (see Fig. 3) of the endless circular path 1A of movement of articles 3 past the testing station in the direction which is indicated by the arrow A. The diaphragm 6 has an article-containing surface 7 which at least partially surrounds the aperture 9 and is in contact with the adjacent ends 3a of successive articles 3 while such ends advance past the testing station, i.e., past the diaphragm 6. The latter further includes a suitably inclined (see Fig. 2) cam face 8 which is located ahead of the surface 7, as considered in the direction of arrow A, and serves to change the axial positions of those articles 3 whose ends 3a extend beyond their prescribed path, i.e., to the right of such path as viewed in Fig. 1 or 2.

The arrangement may be such that successive articles 3 are intentionally transported in axial positions wherein their ends 3a strike against and are shifted by the cam face 8 so that each end 3a reliably contacts the surface 7 and is thus located at an optimum distance from (i.e., in immediate proximity of) the slitshaped aperture 9.

The aperture 9 is actually formed in a blockshaped member 11 of the diaphragm 6, and this member receives the respective ends of two bundles 16 and 17 of fiber optics which together form a composite bundle 12. The radiation receiving ends of fiber optics which constitute the bundle 16 are adjacent to a radiation source 13 (e.g., a light emitting diode) and the radiation discharging or emitting ends of such fiber optics are located in the aperture. Radiation which is supplied by the bundle 16 is reflected by the ends 3a of successive articles 3, and the reflected radiation enters the adjacent ends of the bundle 17 of fiber optics which convey the radiation to a signal generating detector 14, e.g., a photoelectronic transducer.Those ends of the bundles 16 and 17 of fiber optics which are located in the aperture 9 are uniformly distributed so as to ensure that radiation is directed against each portion of an end 3a which advances past the testing station and that reflected radiation is indicative of the characteristics of all portions of the tested end face of the article 3 advancing past the diaphragm 6.

The width of the aperture 9, as considered in the direction of the arrow A, is preferably a small and most preferably a minute fraction of the diameter of an article 3. For example, the width of the aperture 9 can be considerably less than 20 or 25 percent of the diameter of an article 3.

The output of the detector 14 transmits signals to an evaluating circuit 18 which processes such signals and whose output is constituted by an amplifier 22 which can transmit signals for segregation of articles 3 with unsatisfactory ends 3a from the remaining (satisfactory or acceptable) articles. The evaluating circuit 18 further comprises an amplifier 19 which amplifies the signals from the detector 14 and transmits the amplified signals to an operational amplifier 21 which constitutes an integrator and may be of the type known as 3240 manufactured and sold by RCA. The amplifier 21 integrates all signals which are generated during transport of an end 3a past the aperture 9, and the integrated signals are then amplified by the amplifier 22 prior to transmission to a suitable segregating device 31 for defective articles (reference may be had to the aforementioned commonly owned U.S.Pat. No. 3,993,194 to Reuland which discloses a pneumatic ejector for defective articles).

The operational amplifier 21 is reset to zero during intervals between the testing of the ends 3a of successive articles 3. Such resetting is effected by a comparator 23 (e.g., type LM 311 manufactured and sold by Motoroia) which receives signals from the output of the amplifier 19 and generates a signal in response to the absence of reflected radiation during each interval which elapses following the transport of a freshly tested end 3a beyond the aperture 9 and prior to arrival of the next-following end 3a at the testing station.

The evaluating circuit 18 further comprises a signal correcting or modifying circuit 24 which monitors the selected speed of the conveyor 1 and transmits appropriate signals to a programmable operational amplifier 26 (e.g., of the type CA 3080 manufactured and sold by RCA) whose output is connected to one input of the operational amplifier 21. The signals which are transmitted by the output of the operational amplifier 26 are used to modify the signals from the operational amplifier 21 as a function of the selected speed of the conveyor 1 in such a way that the intensity of signals which are transmitted to the amplifier 22 is reduced when the speed of the conveyor 1 is increased and vice versa.The correcting circuit 24 further comprises a rotary disc-shaped pulse generator 29 which is driven in synchronism with the conveyor 1 (e.g. by the main prime mover of a cigarette maker or a filter tipping machine) and cooperates with a proximity detector 28 to generate signals at a frequency which is indictive of the selected speed of the articles 3. The output of the proximity detector 28 is connected with the input of the operational amplifier 26 by a suitable pulse-voltage converter 27.

In the modification illustrated in Figs. 4 and 5 parts of the apparatus corresponding to those of the preferred embodiment are given the same references increased by 100 and are not further described. The modification differs from the first embodiment in that the slitshaped aperture 9 is divided into three sectors or part sensing surfaces 130a, b, c in which separate fibre optic bundles 112a, b, c terminate. The signals emitted by the detectors 114a, b, c associated with the respective fibre optic bundles are fed to separate evaluating circuits 118a, b, c by the amplifiers 119a, b, c.At the output side all three evaluating circuits are connected to a logic OR-gate 132 so that on occurrence of at least one fault signal of one of the part sensing surfaces 130a, b or c monitoring the associated sector of the cigarette head an output signal of the OR-gate 132 appears and can be evaluated by the amplifier 122 for ejecting the respective article.

The apparatus comprises two diaphragms 6, two composite bundles 12 of fiber optics, two radiation sources 13, two detectors 14 and two evaluating or processing circuits 18 if the articles 3 are plain cigarettes and it is desired to test both ends of each article, either simultaneously or sequentially.

An important advantage of the improved method and apparatus is that the evaluating circuit 18 (and more particularly its operational amplifier 21) can transmit signals which are representative of the average quality or condition of the entire end 3a of each tested article 3.

Another important advantage of the improved method and apparatus is that the evaluating circuit 18 (and more particularly the provision of its signal correcting or modifying circuit 24) ensures the generation of output signals which accurately denote the condition or quality of the ends 3a of tested articles 3, irrespective of the selected speed of the conveyor 1 and of the series of articles thereon.

Such articles can be turned out by a cigarette rod maker, a filter rod maker, a filter tipping machine or any other machine for the making of rod-shaped articles which constitute or form part of smokers' products.

A further important advantage of the improved method and apparatus is that the aforediscussed uniform or substantially uniform distribution of the ends of bundles 16 and 17 of fiber optics at the testing station (in the aperture 9) ensures the generation of signals which are indicative of the quality or condition of each and every portion of the tested end 3a of each article 3 which has advanced past the diaphragm 6. Thus, each integrated signal is representative of the quality or condition of the entire cross-section of the respective end 3a. The utilization of a rather narrow aperture 9 and the feature that the detector 14 generates several signals during testing of the end 3a of an article 3 also contribute to the generation of such truly representative integrated signals.

Claims

1. Apparatus for testing the ends of rodshaped articles of the tobacco processing industry, particularly cigarettes, comprising means for transporting a series of articles sideways in a predetermined direction so that one end of each article of the series normally advances along a predetermined path; a source of radiation; a diaphragm having a slitshaped elongated aperture adjacent to and extending transversely of said path; first fiber optics for conveying radiation from said source to said aperture; signal-generating radiation detector means; second fiber optics for conveying to said detector means radiation which is supplied by said first fiber optics and is reflected by the ends of successive articles during transport of such ends past said aperture; and means for processing the signals which are generated by said detector means.

2. The apparatus of claim 1, wherein said diaphragm includes an article-containing surface at least partially surrounding said aperture.

3. The apparatus of claim 2 for optically testing the ends of rod-shaped articles each having a predetermined diameter, wherein the width of said aperture as considered in said direction is a small fraction of said predetermined diameter.

4. The apparatus of claim 3, wherein the width of said aperture is less than one-fourth of said predetermined diameter.

5. The apparatus of claim 2, wherein said detector means is arranged to generate a plurality of signals during transport of the end of an article past said aperture, said processing means including means for integrating the signals which are generated by said detector means during transport of the ends of successive articles past said aperture.

6. The apparatus of claim 5, wherein said integrating means comprises an operational amplifier.

7. Apparatus as claimed in any one of the preceding claims, wherein said aperture is divided into a plurality of part sensing surfaces in which separate fibre optic bundles terminate.

8. Apparatus as claimed in claim 7, wherein each fibre optic bundle is associated with a respective evaluating circuit.

9. The apparatus of claim 2, wherein said transporting means is arranged to transport the articles at a selected one of a plurality of different speeds and said processing means includes means for modifying the signals which are generated by said detector means as a function of the selected speed of tested articles.

10. The apparatus of claim 9, wherein said modifying means includes signal generating means for monitoring the speed of said transporting means and said processing means further comprises a stage receiving signals from said monitoring means and said detector means.

11. The apparatus of claim 2, wherein said first and second fiber optics have at least substantially uniformly distributed end portions adjacent to said aperture.

12. The apparatus of claim 11, wherein said radiation source and said detector means are closely adjacent to said aperture.

13. The apparatus of claim 2, wherein said diaphragm has a cam face located upstream of said article-containing surface, as considered in said direction, and arranged to direct against said surface the ends of all articles which extend beyond said path.

14. The apparatus of claim 13, wherein said cam face merges gradually into said article-contacting surface.

15. The apparatus of claim 2, wherein said path is a circular path and said aperture extends substantially radially of said path.

16. The apparatus of claim 2, wherein said radiation source is a light source.

17. The apparatus of claim 2, further comprising means for effecting segregation from the remaining articles of all such tested articles whose ends reflect radiation in amounts outside of a preselected range.

18. A method of optically testing the ends of rod-shaped articles of the tobacco processing industry, particularly cigarettes, comprising the steps of transporting a series of discrete articles sideways in a predetermined direction so that one end of each article of such series normally advances along a predetermined path; establishing a source of radiation; conveying radiation from said source along a plurality of first discrete paths having radiation discharging ends in a transversely extending narrow portion of said predetermined path so that the radiation is reflected by the ends of successive articles advancing along said predetermined path; conveying reflected radiation from said narrow portion of said predetermined path along a plurality of second discrete paths having radiation receiving ends in said narrow portion of said predetermined path; generating signals denoting the characteristics of radiation which is conveyed along said second discrete paths; processing said signals; and maintaining the ends of successive articles in immediate proximity of the ends of said first and second discrete paths during travel of the ends of articles past said narrow portion of said predetermined path.

19. The method of claim 18, further comprising the step of at least substantially uniformly distributing the ends of said first and second discrete paths in said narrow portion of said predetermined path.

20. The method of claim 18, of testing rod-shaped articles each of which has a predetermined diameter, wherein the width of the narrow portion of said predetermined path is a minute fraction of such predetermined diameter.

21. The method of claim 18, wherein said signal generating step includes generating a plurality of signals during transport of the end of each article past said narrow portion of said predetermined path and said processing step includes integrating the signals which are generated during transport of the end of an article past said narrow portion of said predetermined path.

22. The method of claim 18, wherein said transporting step includes transporting the articles of said series at a selected one of a plurality of different speeds and said processing step includes modifying said signals as a function of the selected speed.

23. The method of claim 18, further comprising the step of axially shifting ahead of said narrow portion of said predetermined path, as considered in said direction, all such rod-shaped articles whose axial positions deviate from a predetermined position.

24. Apparatus for testing the ends of rodshaped articles of the tobacco processing industry, substantially as herein described with reference to the accompanying drawings.

25. A method of optically testing the ends of rod-shaped articles of the tobacco processing industry, substantially as herein described with reference to the accompanying drawings.