Method for checking aerosol-generating articles for manufacturing defects

Abstract

The present invention relates to a method for checking an aerosol-generating article for manufacturing defects, the method comprising: - recording several two-dimensional surface profiles of the aerosol-generating article while rotating the aerosol-generating article; - combining several surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile; - calculating a maximum height difference of the three-dimensional surface profiles; and - rejecting the aerosol-generating article if the maximum height difference of the three-dimensional surface profile exceeds a threshold value.

Description

[Technical field]

[0001] The present invention relates to a method of checking an aerosol-generating article for manufacturing defects.The present invention further relates to an inspection device configured for the detection of manufacturing defects in an aerosol-generating article.The present invention further relates to a system of an inspection device and an aerosol-generating article configured for the detection of manufacturing defects in an aerosol-generating article. [Background technology]

[0002] An aerosol-generating article comprises an aerosol-forming substrate and a substrate section, which often additionally includes a filter section, both of which are covered with a wrapping paper. During the production of the aerosol-generating article, defects may occur in the aerosol-generating article, such as peeling of the wrapping paper, breaks between the connection between the filter section and the substrate section, wrinkles or stains in the wrapping paper, etc. It may be very difficult and time-consuming to detect all the different defects that may occur during the manufacture of the aerosol-generating article. Summary of the Invention [Problem to be solved by the invention]

[0003] It would be desirable to provide a method of checking aerosol-generating articles for manufacturing defects that can detect a number of different defects in a simple manner. Further, it would be desirable to provide a reliable method of checking aerosol-generating articles for manufacturing defects. In addition, it would be desirable to provide a method of checking aerosol-generating articles for manufacturing defects that can be implemented as an in-line process control during the manufacture of the aerosol-generating articles. Furthermore, it may be desirable to provide an accurate method of checking aerosol-generating articles for manufacturing defects. Furthermore, it would be desirable to provide an inspection apparatus that can detect a number of different defects simultaneously. [Means for solving the problem]

[0004] According to one embodiment of the present invention, there may be provided a method of checking an aerosol-generating article for manufacturing defects. The method may comprise recording several two-dimensional surface profiles of the aerosol-generating article while rotating the aerosol-generating article. The method may further comprise combining several surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile. Furthermore, the method may comprise the step of calculating a maximum height difference of the three-dimensional surface profiles. Additionally, the aerosol-generating article may be rejected if the maximum height difference of the three-dimensional surface profile exceeds a threshold value.

[0005] According to another embodiment of the invention, there is provided a method for checking an aerosol-generating article for manufacturing defects. The method comprises recording several two-dimensional surface profiles of the aerosol-generating article while rotating the aerosol-generating article. The several surface profiles recorded at different rotation angles are combined to obtain a three-dimensional surface profile. A maximum height difference of the three-dimensional surface profiles is calculated, and if the maximum height difference of the three-dimensional surface profiles exceeds a threshold value, the aerosol-generating article is rejected.

[0006] Such methods for checking an aerosol-generating article for manufacturing defects may enable the detection of some manufacturing defects, which are not typically easily detected by visual detection methods, and may also enable the detection of manufacturing defects located at different positions around the circumference of the aerosol-generating article.

[0007] The two-dimensional surface profile may be a two-dimensional height profile of the surface of the aerosol-generating article. The two-dimensional height profile of the surface may be along the x-axis and y-axis of a Cartesian coordinate system (xy profile). The two-dimensional height profile may illustrate indentations and bulges on the surface of the aerosol-generating article. The two-dimensional height profile may illustrate height differences on the surface of the aerosol-generating article. The two-dimensional height profile may illustrate the lowest and highest points of the height profile of the surface of the aerosol-generating article.

[0008] Combining several two-dimensional height profiles of a surface recorded at different rotation angles of the aerosol-generating article creates a three-dimensional surface profile that may be aligned along the x-, y- and z-axes of a Cartesian coordinate system (xyz profile).

[0009] These three-dimensional surface profiles may facilitate the detection of manufacturing defects, which result in changes to the surface profile of the aerosol-generating article, such as wrinkles, holes, or protruding sections of the aerosol-generating article.

[0010] The method may include projecting the three-dimensional surface profile onto a two-dimensional plane. The two-dimensional projection of the three-dimensional surface profile may include a plurality of two-dimensional surface profiles disposed one above the other. The two-dimensional plane may illustrate a series of subsequently recorded three-dimensional surface profiles at different rotation angles. The series of subsequently recorded three-dimensional surface profiles may be recorded at equidistant rotation angles. For example, while recording the two-dimensional surface profile, the aerosol-generating article may be rotated in equidistant increments of 1 degree to 9 degrees, preferably 2 degrees to 8 degrees, more preferably 3 degrees to 7 degrees.

[0011] The aerosol-generating article may be rotated 360 degrees while recording several two-dimensional surface profiles. This may allow to obtain a 360 degree three-dimensional surface profile of the entire surface of the aerosol-generating article. Between 30 and 550, preferably at least 200, two-dimensional surface profiles may be acquired, analyzed and potentially recorded for one single aerosol-generating article. All these two-dimensional surface profiles recorded at equidistant rotation angles may be combined into one single three-dimensional surface profile, which may also be called a three-dimensional point cloud.

[0012] Analysis of three-dimensional surface profiles (point clouds) may simplify the detection of manufacturing errors in aerosol-generating articles.

[0013] The aerosol-generating article may be shaped in a tubular form with a central longitudinal axis. During recording of the several two-dimensional surface profiles, the aerosol-generating article may be rotated along its central longitudinal axis. This may allow recording several two-dimensional surface profiles of the aerosol-generating article along the longitudinal axis of the aerosol-generating article at equidistant rotation angles. This may simplify inspection of at least a large section of the aerosol-generating article along the longitudinal axis of the aerosol-generating article. The two-dimensional surface profile may be a two-dimensional height profile of the surface of the aerosol-generating article along the longitudinal axis of the aerosol-generating article.

[0014] The aerosol-generating article may comprise a filter portion and a substrate portion. The substrate portion may comprise an aerosol-forming substrate. The substrate portion may be tubular. A wrapper may be wound around the substrate portion of the aerosol-generating article. The wrapper may comprise paper, cardboard, plastic, or a mixture thereof. The filter portion may comprise a plug of cellulose acetate tow. The filter portion may comprise, for example, a hollow acetate tube (HAT), a fine hollow acetate tube (FHAT), or a plug of tow wound around a central cardboard tube, all of whose constructions are known from the manufacture of filter elements.

[0015] The aerosol-generating article may further comprise tipping paper disposed at least partially wrapped around the filter portion and the substrate portion so as to overlap the filter portion and the substrate portion. The tipping paper may overwrap the filter portion and at least a portion of the substrate portion adjacent the filter portion. The tipping paper may be used to attach components of the aerosol-generating article, in particular the filter portion and the substrate portion, to one another.

[0016] According to a further embodiment of the method of the present invention, several two-dimensional surface profiles of at least the filter portion and part of the substrate portion overwrapped by the tipping paper are recorded, which may allow the detection of manufacturing defects that may occur when the filter portion is connected to the substrate portion via the wrapping paper.

[0017] The aerosol-generating article with a filter portion may be produced by inserting a double-length filter portion between two single-length substrate portions. The double-length filter portion may then be attached to both substrate portions by overwrapping with tipping paper. An adhesive may be applied to the end portions of the tipping paper to allow for closure of the tipping paper around both substrate portions. This may provide a stable connection between both substrate portions and the double-length filter portion. The double-length filter portion is then cut in the middle, releasing two single aerosol-forming articles, each comprising a substrate portion and a filter portion. Manufacturing defects may occur when connecting the double-length filter portion to both substrate portions. The method for checking manufacturing defects may be particularly suitable for detecting any manufacturing defects that may occur during attachment of the filter portion to the substrate portion.

[0018] The threshold value may be the maximum deviation of the surface profile of a particular aerosol-generating article from the surface profile of an aerosol-generating article that does not have a manufacturing defect that is still acceptable during production. The maximum height difference in the combined three-dimensional surface profile of the aerosol-generating article may be determined by selecting the two-dimensional surface profile of the combined three-dimensional surface profile that has the maximum height difference. Hence, the maximum height difference may be calculated as the maximum of all the maximum height differences calculated for each profile. Any aerosol-forming article that has been subjected to the method for checking for manufacturing defects may be accepted as free of defects if the maximum height difference of its three-dimensional surface profile is equal to or less than the threshold value. If the maximum height difference of its three-dimensional surface profile is above the threshold value, the aerosol-generating article may be rejected as containing a defect.

[0019] The threshold value may be between 0.4 and 0.6 millimeters, preferably between 0.48 and 0.52 millimeters.

[0020] Manufacturing defects that may be detected by recording the three-dimensional surface profile are selected from the group consisting of tears, slits, holes, wrinkles, breaks, poor adhesion of the filter portion to the substrate portion, and exposed connections between the filter portion and the substrate portion.

[0021] These manufacturing defects result in changes in the three-dimensional surface profile of the aerosol-generating article that can be easily detected by the method according to the present invention.

[0022] The method of checking aerosol-generating articles for manufacturing defects may be accurate and rapid, and may be part of the manufacturing process for the aerosol-generating articles and may be implemented as an in-line process control during the manufacturing process.

[0023] The method for checking for manufacturing defects may further comprise the step of recording two-dimensional visual images or intensity lines of the surface of the aerosol-generating article while rotating the aerosol-generating article. Several two-dimensional surface visual images or several intensity lines recorded at different rotation angles may be combined to obtain a combined two-dimensional visual surface image. The combined visual surface profile may be compared via image correlation with a defect-free combined visual image of a defect-free aerosol-generating article. If the combined visual surface profile does not match the defect-free visual image, the aerosol-generating article may be rejected.

[0024] To obtain a combined 2D visual surface image, several 2D surface visual images may be combined. Alternatively, several intensity lines, in particular grayscale intensity lines, may be combined into one combined 2D visual surface grayscale image. The recording of the intensity lines, in particular grayscale intensity lines, may be performed with a 2D linear camera.

[0025] Recording several two-dimensional visual images or several intensity lines of the surface of the aerosol-generating article may allow the detection of manufacturing defects that are not easily detected, employing the recording of several two-dimensional surface profiles.

[0026] The at least one first visual marker may be present on a surface of the aerosol-generating article. The location of the first visual marker on the surface of the aerosol-generating article may be determined using the combined two-dimensional visual surface image. The at least one first visual marker may comprise at least one line. The at least one first visual marker may be a line extending around the circumference of the aerosol-generating article. The at least one first visual marker that is a line may be located on the tipping paper. The at least one first visual marker may indicate the location of the tipping paper relative to the substrate portion and the filter portion.

[0027] Additionally, a set of parallel lines may be present as a set of second visual markers. The set of parallel lines may be located on the tipping paper. There may be at least two sets of parallel lines. The at least two sets of parallel lines may be located at different positions on the tipping paper. When the tipping paper is wrapped around the aerosol-generating article, the at least two sets of parallel lines may be located at different positions around the periphery of the article. The at least two sets of parallel lines may allow for detection of the position of the tipping paper around the periphery of the aerosol-generating article relative to the substrate portion.

[0028] All these visual markers may be detected employing the methods described above of recording either several two-dimensional visual images or several lines of intensity and combining these two-dimensional surface visual images or several lines of intensity into a combined two-dimensional visual surface image of the aerosol-generating article. Visual markers may also include markers that indicate the brand of the aerosol-generating article, for example a trademark. Visual markers may also be located on a wrapping paper that overwraps the substrate portion of the aerosol-generating article.

[0029] These visual markers may be suitable for detecting any misalignment of the tipping paper relative to the aerosol-generating article when attaching the filter portion to the base portion. These visual markers may also be suitable for detecting any displacement of the base portion relative to the filter portion or its wrapping paper. These visual markers may also be suitable for detecting wrinkles or overwrap defects in the wrapping paper of the base portion.

[0030] Manufacturing defects that may be detected by recording a visual image or intensity lines on the surface of the aerosol-generating article may be selected from the group consisting of stains, displacement of the tipping paper relative to the substrate portion, mixing of different brands of aerosol-generating articles, and creases in the tipping paper.

[0031] Recording a two-dimensional visual image of the surface of an aerosol-generating article may enable the detection of manufacturing defects that would otherwise not be detectable or would be difficult to detect by recording several two-dimensional surface profiles.

[0032] Any changes in the position or appearance of the visual markers, or any of the manufacturing defects mentioned above, may be detected via image correlation. The actual recorded combined two-dimensional visual surface image may be compared via image correlation to a reference two-dimensional visual surface image of a defect-free aerosol-generating article. Similarly, the position and appearance of a single continuous line or a set of parallel lines extending around the circumference of the aerosol-generating article may be compared to the reference image via image correlation.

[0033] During recording of either the several two-dimensional surface visual images or the several lines of intensity, the aerosol-generating article may be rotated 360 degrees, which may allow combining the several two-dimensional surface visual images or several lines of intensity into a combined 360 degree two-dimensional visual surface image that covers the entire surface of the aerosol-generating article.

[0034] Multiple two-dimensional surface visual images may be recorded at equidistant rotation angles of the aerosol generating device. Between 30 and 550, preferably at least 200, two-dimensional visual surface images may be recorded and combined into one combined two-dimensional visual surface image.

[0035] Several 2D surface profiles and several 2D visual surface images or several intensity lines may be recorded simultaneously, which may allow for simultaneously obtaining 3D surface profiles and combined 2D visual surface images for detecting a wide variety of different manufacturing defects.

[0036] A surface profile sensor may be employed that is configured to record either several two-dimensional surface profiles or several intensity lines of the aerosol-generating article. Similarly, a visual imaging sensor may be employed that is configured to record several two-dimensional visual images of the surface of the aerosol-generating article. One or both of the surface profile sensor and the visual imaging sensor may be a laser sensor.

[0037] According to another embodiment of the method of the present invention, there may be a separate 2D laser sensor and a separate 3D laser sensor, the 2D laser sensor may be configured to record either several 2D surface visual images or several intensity lines, and the 3D laser sensor may be configured to record several 2D surface visual images that are combined into a three dimensional surface profile.

[0038] The two-dimensional laser sensor and the separate three-dimensional laser sensor may be located at different locations, for example one sensor below the aerosol-generating article and one sensor above the article.

[0039] Both the surface profile sensor and the visual imaging sensor are preferably integrated into one single sensor head, which is preferably a line laser sensor head.

[0040] The laser sensor head is - some two-dimensional surface profile, or - It may be employed to record either several two-dimensional surface visual images or several intensity lines, or both.

[0041] This laser sensor head may allow for rapid and accurate recording of both the surface profile and the surface visual image. A line laser sensor head may be employed. The line laser sensor head may comprise a laser source for generating a laser beam and an optical device for projecting the laser beam as a laser line. Thus, the line laser may allow for recording, during one single scanning motion, either a two-dimensional surface profile, or a two-dimensional visual surface image or several intensity lines, or both, over at least a portion, and preferably over the entire length, of the aerosol-generating article.

[0042] One single laser sensor head, preferably a single line laser sensor head, may be used to record either or both of several two-dimensional surface profiles and several two-dimensional surface visual images of the aerosol-generating article. Either several two-dimensional surface profiles and several two-dimensional surface visual images or several intensity lines may be recorded preferably simultaneously.

[0043] This may allow for simultaneous, rapid and accurate detection of both the three-dimensional surface profile and the combined two-dimensional visual surface image. The combination of both detection methods may allow for detection of a variety of different manufacturing defects in the aerosol-generating article that may otherwise be difficult to simultaneously monitor during the manufacturing process of the aerosol-generating article.

[0044] The laser sensor head may be a laser profiler. The laser profiler comprises a combination of a laser light source and an area-scanning high-speed sensor. This allows for the emission of a laser beam and the detection of the laser beam reflected from the surface of the aerosol-generating article in one device. As mentioned above, the laser profiler may comprise a line laser. This may allow for the recording of a surface profile and a surface visual image of a large portion of the surface of the aerosol-generating article in one scanning step. The laser profiler may be a 2D / 3D laser profiler. Such a 2D / 3D laser profiler may comprise a two-dimensional laser scanner or a linear sensor camera and a three-dimensional laser scanner. The two-dimensional laser scanner or the linear sensor camera may be configured to record either several two-dimensional surface visual images or several intensity lines and combine them into a combined two-dimensional visual surface image of the aerosol-generating article. The two-dimensional laser scanner or the linear sensor camera may include a grayscale or RGB linear sensor camera or an area-scanning sensor camera. The three-dimensional laser scanner may be configured to record several two-dimensional surface profiles of the aerosol-generating article and combine them into a three-dimensional surface profile. The 3D laser scanner may record a variety of different 2D surface profiles corresponding to different rotation angles of the aerosol-generating article, which may allow the collection of different recorded data in three-dimensional space, a so-called "3D point cloud acquisition".

[0045] The aerosol-generating article may be rotated at a speed of 16,000 to 1,200, preferably at a speed of 15,000 to 2,400, more preferably at a speed of 15,000 to 10,000 revolutions per minute (rpm).

[0046] Such a speed range may be sufficient to integrate the method for checking manufacturing defects as an in-line process control into the manufacturing process of the aerosol-generating article.

[0047] Aerosol-generating articles are: -Two rotating drums, -One rotating drum and one stationary part, or -It may rotate between either one moving belt and one stationary part.

[0048] Any of these configurations may be suitable for rotating the aerosol-generating article while recording either or both of several two-dimensional surface profiles or several two-dimensional surface visual images.

[0049] Employing two rotating drums is a preferred way of rotating the aerosol-generating article during recording of either or both of several two-dimensional surface profiles or several two-dimensional surface visual images. The two drums may be rotated in opposite directions. Employing two rotating drums may allow the laser sensor to be in a stationary position and still record images of most or preferably the entire surface of the aerosol-generating article due to the rotation. One of the rotating drums may be a vacuum drum. This vacuum drum may comprise vacuum holes for generating a vacuum that can hold the aerosol-generating article in place while the vacuum drum is rotating. The vacuum drum may comprise a different set of vacuum holes that are arranged around the circumference of the drum. The first rotating vacuum drum may have a larger diameter than the other second rotating drum. The vacuum drum may hold the aerosol-generating article to be evaluated in place and rotate the aerosol-generating article during the production process until it reaches the other drum. Once it reaches the other drum, the aerosol-generating article may be disengaged from the vacuum holes and rotated between the vacuum drum and the other drum. During rotation, the laser sensor may record either a number of surface profiles or a number of intensity lines or a number of two-dimensional surface visual images, or both. The aerosol-generating article may then continue to be transported further down the production line by the vacuum drum, when the next set of vacuum holes in the drum re-picks up the aerosol-generating article for further transport.

[0050] Alternatively, the aerosol-generating article may be rotated between one rotating drum and one stationary part. The stationary part may be part of a production line for the aerosol-generating article. The stationary part may be at least partially transparent or partially open to allow inspection of the aerosol-generating article. The rotating drum may be a vacuum drum that holds the aerosol-generating article in place due to vacuum holes and transports the aerosol-generating article to a stationary part. When the aerosol-generating article reaches the stationary part, it is detached from the vacuum holes of the drum and starts to rotate between the rotating drum and the stationary part. The laser sensor may be stationary. The laser sensor may be able to monitor part or the entire surface of the aerosol-generating article due to the rotation of the article.

[0051] The aerosol-generating article may be rotated between one moving belt and one stationary part. The belt may be linear or circular. The stationary part may be part of a production line for producing the aerosol-generating article. Due to the relative movement of the moving belt with respect to the stationary part, the aerosol-generating article is rotated. Thus, in this embodiment, the laser sensor may also be stationary.

[0052] According to another embodiment of the method of the present invention, the aerosol-generating articles are conveyed between a moving belt and a stationary part of the production line. The stationary part may be at least partially transparent or open to allow inspection of the aerosol-generating articles fixed between the belt and the stationary part. For example, the stationary part may be a strap that secures the aerosol-generating articles to the moving belt. In this case, the laser sensor may perform one or both of a rotational or translational movement so that an image can be recorded.

[0053] There may be a mirror configured to be rotatable. If the laser sensor is stationary and the aerosol-generating article is moving relative to the laser sensor, the mirror may rotate to project an image of the aerosol-generating article onto the laser sensor. A rotating mirror may enable the laser sensor to record most or all of the surface of the aerosol-generating article. A rotating mirror may be particularly advantageous when one rotating drum and one fixed part, or one moving belt and one fixed part, are employed.

[0054] The invention also provides an inspection apparatus configured for detection of manufacturing defects in an aerosol-generating article. The inspection apparatus may comprise a surface profile sensor configured to record several surface profiles of the aerosol-generating article. The inspection apparatus may also comprise rotation means configured to rotate the aerosol-generating article during recording of the surface profiles. A surface profile controller may be present in the inspection apparatus, the surface profile controller configured to process several two-dimensional surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile. The surface profile controller may be configured to calculate a maximum height difference of the three-dimensional surface profiles.

[0055] According to a further embodiment of the invention, there is provided an inspection apparatus configured for detection of manufacturing defects in an aerosol-generating article. The inspection apparatus comprises a surface profile sensor configured to record several surface profiles of the aerosol-generating article. Furthermore, the inspection apparatus also comprises rotation means configured to rotate the aerosol-generating article during recording of the surface profiles. A surface profile controller is configured to process the several surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile, and is also configured to calculate a maximum height difference of the three-dimensional surface profile.

[0056] Such an inspection device can simply record the surface profile of the aerosol-generating article at different rotation angles of the aerosol-generating article due to the rotation means. A surface profile controller processes these surface profiles to obtain a three-dimensional surface profile.

[0057] The surface profile controller may further be able to control the rotation means, which may allow reliable recording of several surface profiles at different rotation angles.

[0058] The surface profile controller may be further configured to control the surface profile sensor.

[0059] The inspection apparatus may further comprise a visual imaging sensor configured to record two-dimensional visual images of the surface of the aerosol-generating article while rotating the aerosol-generating article. The inspection apparatus may further comprise a visual imaging controller configured to process several two-dimensional surface visual images at different rotation angles. The visual imaging controller may be configured to process several two-dimensional surface visual images to obtain a combined two-dimensional visual surface image. The visual imaging controller may also be configured to compare the combined visual surface profile with a combined defect-free visual image of a defect-free aerosol-generating article via image correlation.

[0060] Such an inspection device is capable of monitoring a three-dimensional surface profile and additionally a visual image of the surface of the aerosol-generating article. Preferably, the inspection device is configured to simultaneously record either several two-dimensional visual images or several intensity lines of the surface of the aerosol-generating article and several two-dimensional surface profiles.

[0061] Such inspection equipment may be configured to check for a variety of manufacturing defects that can be detected either by employing surface profiling or by visual imaging of the surface of the aerosol-generating article.

[0062] The visual image controller may be capable of controlling the rotating means. The visual image controller may be further configured to control the visual imaging sensor. Preferably, the surface profile controller and the visual image controller are integrated into one control unit.

[0063] The control unit may thus be configured to process several two-dimensional surface visual images and several two-dimensional surface profiles, or both. The control unit may be configured to combine several two-dimensional surface visual images and several two-dimensional surface profiles, or both, to obtain a three-dimensional surface profile and a combined two-dimensional visual surface image, or both. These data may then be processed by the control unit (e.g., by using software) to obtain the three-dimensional surface profile. The control unit may also be configured to control the visual image controller and / or the surface profile sensor.

[0064] Both the surface profile sensor and the visual image controller may be integrated into one sensor head, as already mentioned above. Preferably, this single sensor head is a laser sensor head, more preferably a line laser sensor head. The laser sensor head may be a 2D / 3D laser profiler, as mentioned above. The control unit may control the 2D / 3D laser profiler.

[0065] One example of a 2D / 3D laser profiler is the LJ-V7000 series high speed 2D / 3D laser profiler marketed by Keyence. One specific example of a 2D / 3D laser profiler is the sensor head LJ-V7200B manufactured by Keyence. Another example of a 2D / 3D laser profiler is the 3D machine vision Ranger 3 marketed by Sick.

[0066] One example for a control unit configured to control one or both of the visual image controller and the surface profile sensor (specifically a 2D / 3D laser profiler) is the XG-X series controller marketed by Keyence. One specific example of a controller is the CV-X / XG-X controller that can be connected to any of the LJ-V7000 series high-speed 2D / 3D laser profilers.

[0067] The rotation means is -Two rotating drums, -One rotating drum and one stationary part, or - one moving belt and one stationary part.

[0068] These different embodiments of the rotating means may be controlled by one or both of the visual imaging controller and the surface profile controller, preferably a control unit integrating both the surface profile controller and the visual imaging controller is also configured to control these rotating means.

[0069] Such an inspection apparatus would be configured to provide detection of a wide variety of different manufacturing defects that can be detected using both surface profiling and visual imaging. Such an inspection apparatus would further be configured and fully integrated to provide an automated system of detection of manufacturing defects while rotating the aerosol-generating article.

[0070] It is another object of the present invention to provide an inspection system comprising an inspection apparatus as described herein and an aerosol-generating article, the aerosol-generating article to be inspected for various manufacturing defects as mentioned above.

[0071] The term "aerosol-forming substrate" as used herein relates to a substrate capable of releasing volatile compounds capable of forming an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may conveniently be part of an aerosol-generating article or a smoking article.

[0072] An aerosol-forming substrate is a substrate capable of releasing volatile compounds capable of forming an aerosol. The volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise a homogenized plant-based material (including homogenized tobacco) made, for example, by a papermaking process or a casting process.

[0073] The aerosol-forming substrate may include at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Suitable aerosol formers are, for example, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). The aerosol former may be a polyhydric alcohol or a mixture thereof (such as triethylene glycol, 1,3-butanediol, glycerin, etc.). The aerosol former may be propylene glycol. The aerosol former may include both glycerin and propylene glycol.

[0074] The aerosol-generating article may generate the aerosol by igniting the article and heating the aerosol-forming substrate above its combustion temperature. Alternatively, the aerosol-generating article may generate the aerosol by heating the aerosol-forming substrate below its combustion temperature. Such aerosol-generating articles may be referred to as "heat-free combustion products."

[0075] The following provides a non-exhaustive list of non-limiting examples, any one or more of the features of which may be combined with any one or more features of the other examples, embodiments, or aspects described herein.

[0076] Example A: A method for checking an aerosol-generating article for manufacturing defects, comprising: - recording several two-dimensional surface profiles of the aerosol-generating article while rotating the aerosol-generating article; - combining several surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile; - calculating the maximum height difference of a three-dimensional surface profile; - rejecting the aerosol-generating article if a maximum height difference of its three-dimensional surface profile exceeds a threshold value. Example B: A method as described in Example A, in which the three-dimensional surface profile is projected onto a two-dimensional plane, preferably the two-dimensional projections of several combined surface profiles comprise a series of two-dimensional surface profiles recorded at equidistant rotation angles. Example C: A method according to any of Examples A-B, wherein the aerosol-generating article is shaped in a tubular form with a central longitudinal axis, preferably the aerosol-generating article is rotated along its longitudinal axis and several two-dimensional surface profiles of the aerosol-generating article are recorded along the longitudinal axis at equidistant rotation angles, more preferably the two-dimensional surface profiles are two-dimensional height profiles of the surface of the aerosol-generating article along the longitudinal axis. Example D: The method of any of Examples A to C, wherein the aerosol-generating article comprises a filter portion and a substrate portion, the substrate portion comprising an aerosol-forming substrate, and the aerosol-generating article further comprises tipping paper overwrapping the filter portion and at least a portion of the substrate portion adjacent the filter portion. Example E: A method as described in the preceding Example D, wherein several two-dimensional surface profiles of at least the filter portion and part of the substrate portion overwrapped by tipping paper are recorded. Example F: The method of any of Examples A to E, wherein the threshold for the maximum height difference is the maximum distance between the lowest point and the highest point in the three-dimensional surface profile, preferably the threshold is 0.44 to 0.52 millimeters, preferably 0.46 to 0.50 millimeters, more preferably 0.47 to 0.49 millimeters. Example G: The method of any of Examples A-F, wherein the manufacturing defect is selected from the group consisting of tears, slits, holes, wrinkles, breaks, poor adhesion of the substrate portion to the filter portion, and exposed connections between the filter portion and the substrate portion. Example H: Additionally, - while rotating the aerosol-generating article, a two-dimensional visual image of the surface of the aerosol-generating article is recorded; - combining several two-dimensional surface visual images or intensity lines recorded at different rotation angles to obtain a combined two-dimensional visual surface image, - comparing the combined visual surface profile to a non-defective combined visual image of a non-defective aerosol-generating article via image correlation; The method of any one of claims A to G, wherein the aerosol-generating article is rejected if its combined visual surface profile does not match the defect-free visual image. Example I: The method of any one of Examples A to H, wherein at least one visual marker is present on the surface of the aerosol-generating article and the position of the visual marker on the surface of the aerosol-generating article is determined using the combined two-dimensional visual surface image, preferably the visual marker comprises at least one line. Example J: The method described in the preceding Examples I and D, wherein at least one visual marker is present on the tipping paper, and the position of the visual marker on the surface of the aerosol-generating article is used to determine the position of the tipping paper relative to the substrate portion. Example K: The method of any of Examples H-J, wherein the manufacturing defect is selected from the group consisting of stains, displacement of the tipping paper relative to the substrate portion, mixing of different brands of aerosol-generating articles, and creasing of the tipping paper. Example L: The aerosol-generating article is rotated 360 degrees and - 360 degree 3D surface profile, or The method of any of embodiments A-K, wherein one or both of the combined 360 degree two-dimensional visual surface images are obtained. Example M: ​​A line laser sensor - several two-dimensional surface profiles, or The method of any of embodiments A to L, adapted to record one or both of several two-dimensional surface visual images. Example N: The method described in the preceding Example L, in which a single line laser sensor is employed to record several surface profiles and / or several two-dimensional surface visual images or intensity lines of the aerosol-generating article, preferably several surface profiles and several two-dimensional surface visual images are recorded simultaneously. Example O: An aerosol-generating article comprising: -Two rotating drums, - one rotating drum and one stationary part, The method according to any of embodiments A-N, wherein the rotation is between one moving belt and one stationary part. Example P: The method of any of Examples A-O, wherein two different sensors are employed to record several two-dimensional surface visual images and several surface profiles. Example Q: An inspection device configured for detection of manufacturing defects in an aerosol-generating article, comprising: a surface profile sensor configured to record several two-dimensional surface profiles of the aerosol-generating article; and - a rotating means configured to rotate the aerosol-generating article during recording of the surface profile; - an inspection apparatus comprising: a surface profile controller configured to process several two-dimensional surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile, and configured to calculate a maximum height difference of the three-dimensional surface profile. Example R: a visual imaging sensor configured to record several two-dimensional visual images or intensity lines of the surface of the aerosol-generating article while rotating the aerosol-generating article; The inspection apparatus of preceding Example Q, further comprising: a visual imaging controller configured to process several two-dimensional surface visual images or intensity lines at different rotation angles to obtain a combined two-dimensional visual surface image, and configured to compare the combined visual surface profile with a combined defect-free visual image of a defect-free aerosol-generating article via image correlation. Example S: The inspection apparatus of the preceding example R, wherein the visual imaging sensor and the surface profile sensor are integrated within one single sensor head, preferably the sensor head being a line laser sensor head. Example T: An inspection apparatus as described in any preceding example Q-S, wherein the surface profile controller and the visual imaging controller are integrated into one single control unit. Embodiment U: The rotating means is -Two rotating drums, - one rotating drum and one stationary part, -An inspection device as described in any of the preceding embodiments Q to T, comprising one moving belt and one stationary part. Example V: An inspection system comprising an inspection device described in any of the preceding Examples Q to U and an aerosol-generating article.

[0077] Features described with respect to one embodiment may be equally applied to other embodiments of the invention.

[0078] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0079] [Figure 1] FIG. 1 shows a schematic perspective view of an inspection device and an inspection system according to one embodiment of the present invention. [Diagram 2] FIG. 2 shows a schematic diagram of a 2D / 3D laser profiler inspecting an aerosol-generating article between a first rotating drum and a strap. [Figure 3A-3B]3A and 3B show cross-sectional views of a 2D / 3D laser profiler scanning an aerosol-generating article rotating between two rotating drums. [Figure 4] FIG. 4 illustrates another schematic perspective view showing a moving 2D / 3D profiler inspecting an aerosol-generating article rotating between a moving belt and straps. [Figure 5A-5B] 5A and 5B show a photograph of a defect-free dual stick containing two aerosol-generating articles connected via a filter portion, and a single two-dimensional surface profile of one of the dual sticks, respectively. [Figure 6A-6B] 6A and 6B show a photograph of a dual stick containing two aerosol-generating articles containing a manufacturing defect, and a single two-dimensional surface profile of one of the dual sticks, respectively. [Figure 7] FIG. 7 shows a three-dimensional surface profile of an aerosol-generating article containing a manufacturing defect projected onto a two-dimensional plane. [Figure 8A-8B] 8A and 8B show two different combined two-dimensional visual surface images of two different aerosol-generating particles having manufacturing defects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0080] In the following, like elements are designated by like reference numerals throughout the figures.

[0081] FIG. 1 illustrates an inspection device and an inspection system configured for detection of manufacturing defects in an aerosol-generating article according to one embodiment of the present invention. The inspection device is preferably employed as a so-called "in-line quality inspection" during the manufacturing process of the aerosol-generating article. The inspection device comprises a laser sensor 12 (notably a 2D / 3D laser profiler including a laser 12A and a sensor 12B integrated in one sensor head). The 2D / 3D laser profiler scans the surface of the aerosol-generating article 10 or the surface of a so-called "dual stick" 2×10 containing two aerosol-generating articles (which are connected by a double filter part connected to a substrate part on both sides). In the following, when referring to an "aerosol-generating article" 10, this is meant to include a "dual stick" 2×10 as well, unless otherwise stated. The 2D / 3D laser profiler may be configured to simultaneously record several two-dimensional surface profiles and several two-dimensional surface visual images of the aerosol-generating article or the dual stick. The aerosol-generating article is rotated between a first rotating drum 14 and a second rotating drum 16, which are rotating means. The first rotating drum rotates in a direction indicated by arrow 14A, and the second rotating drum 16 rotates in an opposite direction indicated by arrow 16A. This allows the 2D / 3D laser profiler to scan a large portion of the surface of the aerosol-generating article 10, preferably the entire surface of the aerosol-generating article if the article rotates 360 degrees. During the scanning process, the 2D / 3D laser profiler is held stationary. The first rotating drum 14 includes a protrusion 14B, which can carry the aerosol-generating article 10 further through the manufacturing process. Initially, the aerosol-generating article 10 is held in place on the first rotating drum 14 via a vacuum hole 14C. When the aerosol-generating article held by the vacuum hole 14C reaches the second rotating drum 16, the article starts to rotate and inspection of the article by the 2D / 3D laser profiler begins. Inspection of the aerosol-generating article ends when the next protrusion 14 B of the first rotatable drum 14 pushes the aerosol-generating article 10 away from the second rotatable drum 16 .Thus, the aerosol-generating article 10 is rotated between the first and second rotating drums 14 between adjacent protrusions 14B of the first rotating drum 14. The first rotating drum 14 and the second rotating drum 16 and the 2D / 3D laser profiler are connected to a control unit 18 via a communication connection 22. The control unit 18 is configured to process either several two-dimensional surface visual images or several intensity lines and / or several two-dimensional surface profiles. In particular, the control unit 18 may be configured to combine either several two-dimensional surface visual images or several intensity lines to obtain a combined dimensional visual surface image. Similarly, the control unit 18 may be configured to combine several two-dimensional surface profiles to obtain a three-dimensional surface profile. There is a workstation 20 connected to the control unit 18 via the communication connection 22. The workstation 20 allows a user to handle an inspection device. Such an inspection device is configured to provide an in-line inspection of the manufactured aerosol-generating articles during the manufacturing process. This in-line inspection allows for the detection of a variety of different manufacturing defects, which can preferably be detected by either visual imaging or surface profiling. Thus, this inspection apparatus allows a user to implement the method of checking for manufacturing defects of the present invention in an automated manner.

[0082] Figure 2 illustrates another embodiment of a rotating means for an inspection apparatus that may be integrated into the inspection apparatus of Figure 1 instead of two rotating drums. In this embodiment, the rotating means includes a first rotating drum 14 and straps 24 that secure the aerosol-generating article 10 to the rotating drum. In this case, the 2D / 3D laser profiler 12, including laser 12A and sensor 12B, must move together with the first drum to inspect different portions of the surface of the aerosol-generating article.

[0083] FIG. 3A illustrates in cross-section two rotating drums 14 and 16, which rotate in opposite directions as a rotating means. FIG. 3B shows cross-sectional views of different subsequent steps of transporting an aerosol-generating article 10 using the two rotating drums 14 and 16. In a first step, labeled "a"), the aerosol-generating article 10, held in place by the vacuum holes of the first rotating drum 14, is caught between the drums 14 and 16 and starts to rotate (the vacuum holes are not shown in FIG. 3B). During rotation, a 2D / 3D laser profiler scans the surface of the aerosol-generating article, as shown in the second step, labeled "b") (only the beams 12A and 12B of the laser profiler are shown). In a final step, labeled "c"), the next protrusion 14B of the first rotating drum 14 picks up the aerosol-generating article 10 for further transport through the manufacturing process, thereby completing the inspection of the aerosol-generating article.

[0084] Figure 4 illustrates a perspective schematic view of another embodiment of a rotation means that can be incorporated into the inspection apparatus shown in Figure 1. In this case, the aerosol-generating article 10 is fixed between a moving belt 26 and a strap 24. As the strap 24 is a stationary part of the apparatus, the aerosol-generating article 10 starts to rotate between the stationary strap 24 and the moving belt 26 and at the same time moves in the direction indicated by arrow 15 (rotational translation of the aerosol-generating article). In order to scan all or most of the surface of the aerosol-generating article, the 2D / 3D profiler 12 has to follow the translation of the aerosol-generating article indicated by arrow 15.

[0085] FIG. 5A shows a photograph of a dual stick 2×10 including two substrate pieces 10B connected to one dual filter piece 10A by tipping paper. The dashed lines in FIG. 5A indicate the cut lines for cutting the dual stick to produce two single aerosol-generating articles 10. In this case, the dual stick does not contain any manufacturing defects. There is one continuous first visual marker 10C on the dual stick, which is a line that extends around the circumference of the dual stick. In addition, there is a set of second visual markers 10D on the tipping paper of the dual stick. The first and second sets of visual markers can be used to monitor the correct position of the tipping paper when connecting the dual filter piece 10A to both substrate pieces 10B.

[0086] Figure 5B shows a single 2D surface profile of one of the dual sticks shown in Figure 5A. Since there are no defects in this dual stick, the 2D surface profile is flat and does not show any large protrusions above a threshold level.

[0087] 6A shows a photograph of another dual stick 2×10 that contains a manufacturing defect 30. Specifically, the tipping paper has been peeled away from the dual stick and protrudes from the dual stick.

[0088] Figure 6B shows a single two-dimensional surface profile 28 of the dual stick shown in Figure 6A in an area where a manufacturing defect 30 is present. The protrusion 30 of the manufacturing defect is clearly visible in the two-dimensional surface profile 28. Recording the two-dimensional surface profiles and combining them into a three-dimensional surface profile is therefore particularly suitable for detecting manufacturing defects that involve changes in the surface profile of the dual stick.

[0089] FIG. 7 shows a two-dimensional projection 32 of a three-dimensional surface profile. Several two-dimensional surface profiles 28 are aligned one on top of the other. Adjacent surface profiles 28 are separated by a so-called "step size" 34, which is an equidistant rotation angle. One single two-dimensional surface profile 28 is indicated by a single bright line in FIG. 7. For clarity, only a few bright lines are labeled with reference numbers 28. The manufacturing defect 30 is clearly visible in the three-dimensional surface profile 32.

[0090] Figures 8A and 8B show different combined two-dimensional visual surface images of a dual stick with a manufacturing defect. Such a greyscale surface image can be obtained by combining various different greyscale intensity lines recorded at different rotation angles of the aerosol-generating article. In Figure 8A, the second set of visual markers 10D is not straight, but wavy as shown in the circle labeled 38, possibly due to misalignment of the tipping paper in this area. In Figure 8B, a stain 40 is present as a manufacturing defect. In both cases, visual imaging of the dual stick is well able to detect both manufacturing defects.

Claims

1. 1. A method for checking an aerosol-generating article for manufacturing defects, comprising the steps of: - recording several two-dimensional surface profiles of the aerosol-generating article while rotating the aerosol-generating article; - combining several surface profiles recorded at different rotation angles to obtain a three-dimensional surface profile; - calculating the maximum height difference of said three-dimensional surface profile; - rejecting the aerosol-generating article if the maximum height difference of its three-dimensional surface profile exceeds a threshold value, and additionally, - while rotating the aerosol-generating article, a two-dimensional visual image of the surface of the aerosol-generating article is recorded; - several two-dimensional surface visual images or intensity lines recorded at different rotation angles are combined to obtain a combined two-dimensional visual surface image, - the combined visual surface image is compared via image correlation to a non-defective combined visual image of a non-defective aerosol-generating article; if the combined visual surface image does not match the defect-free visual image, the aerosol-generating article is rejected.

2. 2. The method of claim 1, wherein the aerosol-generating article comprises a filter portion and a substrate portion, the substrate portion comprising an aerosol-forming substrate, and the aerosol-generating article further comprises tipping paper overwrapping the filter portion, and at least a portion of the substrate portion is adjacent to the filter portion.

3. The method according to any of claims 1 to 2, wherein several two-dimensional surface profiles of at least the filter portion and part of the substrate portion overwrapped by the tipping paper are recorded.

4. 2. The method of claim 1, wherein the manufacturing defects are selected from the group consisting of tears, slits, holes, wrinkles, breaks, poor adhesion of the substrate portion to the filter portion, and exposed connections between the filter portion and the substrate portion.

5. 2. The method of claim 1, wherein at least one visual marker is present on the surface of the aerosol-generating article and the position of the visual marker on the surface of the aerosol-generating article is determined using the combined two-dimensional visual surface image, preferably the visual marker comprises at least one line.

6. 2. The method of claim 1, wherein the manufacturing defects are selected from the group consisting of stains, displacement of the tipping paper relative to the substrate portion, mixing of different brands of aerosol-generating articles, and creasing of the tipping paper.

7. the aerosol-generating article is rotated 360 degrees; and -360 degree three-dimensional surface profile, or 2. The method of claim 1, wherein one or both of the combined two-dimensional visual surface images of -360 degrees are obtained.

8. The line laser sensor - said several two-dimensional surface profiles, or The method of claim 1, adapted to record one or both of several two-dimensional surface visual images.

9. 1. An inspection apparatus configured for detection of manufacturing defects in an aerosol-generating article, comprising: - a surface profile sensor configured to record several two-dimensional surface profiles of said aerosol-generating article; - rotating means configured to rotate the aerosol-generating article during said recording of the surface profile; a surface profile controller configured to process said several two-dimensional surface profiles recorded at different rotation angles in order to obtain a three-dimensional surface profile and configured to calculate a maximum height difference of said three-dimensional surface profile, a visual imaging sensor configured to record several two-dimensional visual images or intensity lines of the surface of the aerosol-generating article while rotating the aerosol-generating article; - a visual imaging controller configured to process several of the two-dimensional surface visual images or intensity lines at different rotation angles to obtain a combined two-dimensional visual surface image, and configured to compare the combined visual surface image with a combined defect-free visual image of a defect-free aerosol-generating article via image correlation.

10. 10. The inspection apparatus of claim 9, wherein the visual imaging sensor and the surface profile sensor are integrated in one single sensor head, preferably the sensor head being a line laser sensor head.

11. 11. An inspection apparatus according to claim 9 or claim 10, wherein the surface profile controller and the visual imaging controller are integrated into one single control unit.

12. The rotating means is - Two rotating drums, - one rotating drum and one stationary part, An inspection device according to claim 9, comprising either: a moving belt and a stationary part.

13. An inspection system comprising the inspection device according to claim 9 and an aerosol-generating article.

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