METHOD FOR CHECKING A PRODUCT WITH A VENTILATION ZONE FOR THE PRESENCE OF MANUFACTURING DEFECTS AND AN INSTALLATION FOR CHECKING

Abstract

The invention relates to a method for inspecting an aerosol-generating article for manufacturing defects, the method comprising the method steps: A) providing the aerosol-generating article comprising a ventilation zone with perforations, the article furthermore comprising a longitudinal axis, B) subjecting the perforations to light pulses while rotating the aerosol-generating article about the longitudinal axis, C) determining any light being reflected by the perforations, and D) assessing based on the reflected light whether a manufacturing defect is present in the perforations of the ventilation zone. This method provides an easy way of inspecting an aerosol-generating article for manufacturing defects in the ventilation zone.

Description

[0001] METHOD FOR INSPECTING AN ARTICLE WITH A VENTILATION ZONE FOR MANUFACTURING DEFECTS AND INSPECTION APPARATUS

[0002] The present invention relates to a method for inspecting an aerosol-generating article comprising a ventilation zone with perforations for manufacturing defects. The present invention also relates to an inspection apparatus for carrying out the method for inspection. The aerosol-generating article may comprise an aerosol-forming substrate and may be adapted to produce an inhalable aerosol upon heating.

[0003] Aerosol-generating articles in which an aerosol-forming substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-forming substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0004] Aerosol-generating articles with a ventilation zone including perforations are known. These ventilation zones allow ambient air to enter the aerosol-generating article during a user’s puff. This enables a better mixing of the air flow coming from the aerosol-forming substrate with the ambient air for facilitating the formation of an aerosol. The amount of air which may enter the aerosol-generating article during the user’s puff depends on the number, positions and the shape of the perforations. These perforations may be hard to form with low variability during a manufacturing process for the aerosol-generating articles.

[0005] It would be desirable to provide a method for inspecting an aerosol-generating article with a ventilation zone for manufacturing defects that can be operated efficiently and at high speed, and which provides aerosol-generating articles with uniform ventilation zones. It also would be desirable to provide a method for inspecting an aerosol-generating article for manufacturing defects while manufacturing the articles.

[0006] According to an embodiment of the present invention there is provided a method for inspecting an aerosol-generating article for manufacturing defects. The method may comprise the method steps of A) providing the aerosol-generating article comprising a ventilation zone with perforations, the article furthermore comprising a longitudinal axis. The method furthermore may comprise the method step B) subjecting the perforations to light pulses while rotating the aerosol-generating article about the longitudinal axis. The method for inspecting may comprise the method step C) determining any light being reflected by the perforations. The method for inspecting may comprise the method step D) assessing based on the reflected light whether a manufacturing defect is present in the perforation of the ventilation zone. A further embodiment of the invention provides a method for inspecting an aerosolgenerating article for manufacturing defects. The method for inspecting comprises the method step A) providing the aerosol-generating article, comprising a ventilation zone with perforations, wherein the article furthermore comprises a longitudinal axis. The method for inspection furthermore comprises the method step B) subjecting the perforations to light pulses while rotating the aerosol-generating article about the longitudinal axis. The method for inspecting furthermore comprises the method step C) determining any light being reflected by the perforations, and the method step D) assessing based on the reflected light whether a manufacturing defect is present in the perforations of the ventilation zone.

[0007] Such a method for inspecting an aerosol-generating article for manufacturing defects may be employed during the manufacturing of the aerosol-generating articles. This method may be employed in a quick manner. This method for inspecting an aerosol-generating article for manufacturing defects may allow to quickly change the manufacturing process based on the detected manufacturing defects.

[0008] The method may allow the detection of manufacturing defects in the perforations of the ventilation zone. This method may allow the detection of the manufacturing defects in the ventilation zone during or right after the manufacturing process of the ventilation zones.

[0009] The method may allow the inspection of a plurality of perforations for manufacturing defects in a ventilation zone by subjecting different perforations in the same ventilation zone of an aerosol-generating article to light pulses while rotating the same aerosol-generating article. This may allow the inspection of a large plurality of perforations in a ventilation zone of the same aerosol-generating article for manufacturing defects in a short period of time.

[0010] The ventilation zone may be configured to allow the entry of air from the outside of the aerosol-generating article into the interior of the aerosol-generating article. The additional air may be mixed with the airstream generated from the aerosol-forming substrate of the substrate section of the aerosol-generating article for forming an aerosol. The ventilation zone may be located downstream of the substrate section comprising the aerosol-forming substrate.

[0011] As used herein, the terms “upstream”, and “downstream”, are used to describe the relative positions of sections of the aerosol-generating article in relation to the direction in which the aerosol is transported through the aerosol-generating article during use. The aerosolgenerating article according to the invention comprises a proximal end through which, in use, an aerosol exits the aerosol-generating article. The proximal end of the aerosol-generating article may also be referred to as the mouth end or the downstream end. In use, a user draws on the downstream or mouth end of the aerosol-generating article in order to inhale an aerosol generated by the aerosol-generating system. The aerosol-generating article comprises an upstream end opposed to the downstream or mouth end. The mouth end is downstream of the distal end. The distal end of the aerosol-generating article may also be referred to as the upstream end. Components, or portions of components of the aerosol-generating article may be described as being upstream or downstream of one another based on their relative positions to the direction in which the aerosol is transported through the aerosol-generating article during use of the article or the aerosol generating device. The aerosol-generating article can be used in conjunction with an aerosol-generating device for heating the substrate section of the article in order to generate an inhalable aerosol.

[0012] During method step D) the reflected light determined in method step C) may be compared to a reference range for the reflected light. This may allow the assessment whether any manufacturing defects are present in the perforations of the ventilation zone or not.

[0013] If the reflected light determined in method step C) is within the reference range for the reflected light, then the perforations in the ventilation zone may be within the specifications required for the perforations. If the light being reflected by the perforations is outside of the reference range, then a manufacturing defect may be present in the perforations. In particular, if an intensity of the reflected light is outside of the reference range and above the reference range, then manufacturing defect may be present in the perforations of the aerosol-generating article.

[0014] The reference range may refer to a percentage range of the intensity of the light which have been applied to the perforations in method step B) of the method and which is reflected by the perforations. The reference range may be between 0 percent and 6 percent of the light intensity of the light applied to the perforations, preferably between 0.5 percent and 4 percent of the light applied to the perforations.

[0015] An intensity of reflected light being outside of the reference range may indicate a manufacturing defect in the perforations of the ventilation zone. Preferably, a lack of reflected light being detected in method step C) may indicate a correct perforation without a manufacturing defect. Any light being emitted towards a perforation without manufacturing defects may simply pass through the perforation into the interior of the aerosol-generating article without being reflected.

[0016] The light pulses may be applied while rotating the aerosol-generating article in such a way that the ventilation zone is subjected to light in positions within the ventilation zone during the rotation where perforations are located. Light pulses may not be applied during the rotation in positions of the ventilation zones where perforations are not located. The light pulses may be applied with a frequency allowing positions of perforations within the ventilation zone to be subjected to light. This may allow to selectively apply light to suspected positions of perforations within the ventilation zone during the rotation of the aerosol-generating article.

[0017] For example, if the product specification requires 9 perforations per ventilation zone, each light pulse may be provided at an angle of rotation of 360 degrees / 9 equaling 40 degrees. Likewise, if the product specification requires 11 perforations each light pulse will be provided at the rotation angle of 360 degrees / 11 equaling 33 degrees.

[0018] Any light within a wavelength of 400 nanometers to 800 nanometers may be used in order to assess whether the perforations in the ventilation zone have manufacturing defects or not.

[0019] Any light source producing light pulses may be used for the method of the present invention. Preferably, xenon lamps or pulsed LED lamps are employed, which can produce light pulses of a broad wavelength spectrum of non-coherent light. The pulsed light source may be driven by an energy source which is pulsed.

[0020] A number of perforations may be arranged in an outer wall of the ventilation zone of the aerosol-generating article. The outer wall of the ventilation zone may comprise or be made of a light reflective material being reflective for the light of the light pulses. The light pulses applied to the perforations in method step B) may in part be reflected by parts of the outer wall of the ventilation zone being one or both located adjacent to the perforations or being located within the perforations. This may indicate an offset in one or both the position of a perforation within the ventilation zone in comparison to the position of a correct perforation or a different angle of the perforation reaching into the interior of the article in comparison to a correct perforation.

[0021] The ventilation zone of the aerosol-generating article may be circumscribed by a light reflective wrapper. The light pulses applied to the perforations in method step B) may in part be reflected by parts of the reflective wrapper being located adjacent to the perforations.

[0022] An area of the light reflective material of the outer wall of the ventilation zone reflecting the light pulses applied in method step B) may increase if the manufacturing errors increase. An area of the light reflective wrapper reflecting the light pulses applied in method step B) may increase with an increase in the manufacturing errors.

[0023] An increase in the manufacturing errors may be characterized by an increase in the deviation from the specifications of a perforation without manufacturing error. In particular, an increase of the manufacturing error may be characterized by an increasing deviation of a perforation from a correct, expected position of a perforation without manufacturing error. In particular, an increase of the manufacturing error may be characterized by an increasing tilting angle of the sidewalls of a perforation in comparison to the correct, expected sidewalls of a perforation without any manufacturing error.

[0024] Each of the perforations may have an actual width extending between opposing sidewalls of the outer wall of the ventilation zone. Each of the perforations may have an actual depth extending from the exterior of the outer wall through the outer wall towards the interior of the aerosol-generating article. Each of the perforations may have an actual position on the circumference of the outer wall. An intensity of reflected light detected in method step C) may indicate a deviation of the actual width of the perforation subjected to the light from a correct width expected for a perforation without any manufacturing defect. The intensity of reflected light may also indicate a deviation of the actual depth of the perforation subjected to the light from the correct depth of a perforation without any manufacturing defect. The intensity of reflected light may also indicate a deviation of the actual position of the perforation from a correct position of a perforation without any manufacturing defect. The intensity of reflected light may also indicate a deviation of the actual number of perforations from a correct number of perforations which is present in a ventilation zone without any manufacturing defects.

[0025] The terms “actual width”, “actual depth”, “actual position” and “actual number” refer to the width, depth, and the number of perforations in the ventilation zone which are present in perforations of a ventilation zone of a manufactured aerosol-generating article and which may differ from the respective width, depth, position and number of perforations expected for a perforation being within the required specifications without manufacturing defects.

[0026] The perforations in the ventilation zones may be arranged in an outer wall of the ventilation zone. The outer wall of the ventilation zone may comprise or be made of a light reflective material. The light reflective material of the outer wall of the ventilation zone may comprise one or more materials selected from the group consisting of: cellulose acetate, cardboard, crimped paper and polymeric materials. The ventilation zone may be formed in a hollow tube section of the aerosol-generating article. The hollow tube of the ventilation zone may be a hollow acetate tube (HAT) or a cardboard tube. Light pulses being sent towards the perforations in the ventilation zone in method step B) may be reflected by the light reflective material of the outer wall of the ventilation zone.

[0027] The ventilation zone may be circumscribed by a light reflective wrapper. The light reflective wrapper may preferably comprise or be formed of a paper wrapper or a cardboard wrapper.

[0028] The reflected light detected in method step C) may be reflected from one or both: the light reflective wrapper and the light reflective material of the outer wall of the ventilation zone.

[0029] An intensity of the reflected light detected in method step C) may increase if a deviation of the actual width from the correct with of a perforation increases. An intensity of the reflected light may increase if a deviation of the actual depth of a perforation from the correct depth of a perforation without manufacturing defect increases. An intensity of the reflected light may increase if a deviation of actual position of a perforation from the correct position of a perforation increases.

[0030] The larger the deviation of an actual width of opposing sidewalls of the outer wall of the ventilation zone for a perforation is in comparison to the correct width of the opposing sidewalls of a perforation without manufacturing defects, the larger may be the area of the outer wall of the ventilation zone which reflects the light pulses applied to the perforation in method step C). Therefore, the intensity of the light being reflected by the perforations, determined in method step C) may increase with an increasing deviation of the actual width of a perforation in comparison to a correct width, expected for a perforation without manufacturing defects.

[0031] The larger the deviation of an actual depth of a perforation is in comparison that of a perforation being within the specification, the larger may be the area of sidewalls within the perforation which can reflect the light pulses applied to the perforation in method step B). Thus, the intensity of the light being reflected by the perforations determined in method step B) may increase with an increasing deviation of the actual depth of a perforation in comparison to the correct depth.

[0032] Likewise, the larger the deviation of an actual position of our perforation within the ventilation zone is in comparison to the expected, correct position of the perforation, the larger may be the area of either the outer wall of the ventilation zone or the area of the light reflective wrapper which can reflect the light pulses applied to the perforations in method step B).

[0033] The perforations may be arranged in an outer wall of the ventilation zone, wherein each of the perforations may comprise a central longitudinal perforation axis. The aerosolgenerating article may furthermore comprise a central longitudinal article axis. A number of perforations may be located at different rotational positions on a circumference of the outer wall. The different rotational positions may correspond to different rotation angles of each central longitudinal perforation axis with regard to the central longitudinal article axis. The light pulses may be applied in method step B) at the respective different rotational positions of the perforations. In particular, the light pulses may be applied at the expected, correct rotational positions of the perforations, where the positions of the perforations are expected to be located in the case that the perforations are within the required specifications without manufacturing defects.

[0034] The aerosol-generating article may be a continuous double article. The continuous double article may be made of two aerosol-generating articles, wherein each article may comprise a separate ventilation zone with perforations. Method steps B) and C) may be applied to each of the separate ventilation zones of the double article simultaneously.

[0035] This may allow an easy and quick inspection of a continuous double article being made of two aerosol-generating articles.

[0036] Each of the two aerosol-generating articles included in the continuous double article may comprise a filter section, in particular a mouthpiece filter section. The mouthpiece filter section may be made of a typical filter material such as cellulose acetate. Each of the two aerosol-generating articles may additionally comprise a hollow tube section upstream of the mouthpiece filter section. The hollow tube section may be configured to include a ventilation zone allowing the additional entry of air into the aerosol-generating article. A substrate section comprising an aerosol-forming substrate may be located upstream of the hollow tube section, further upstream of the substrate section another filter section may be located. This filter section may reduce or avoid the leakage of aerosol-forming substrate out of the aerosolgenerating article.

[0037] The aerosol-forming substrate may comprise an aerosol-former. An aerosol-former is any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the temperature of operation of the aerosol-generating system. Suitable aerosol-formers may include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Aerosol formers may be polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1 ,3-butanediol and glycerine. The aerosol-former may be propylene glycol. The aerosol former may include both glycerine and propylene glycol. The aerosol former may only include glycerine.

[0038] The aerosol-former may be present in an amount of 20 weight percent to 58 percent, preferably 25 weight percent to 45 weight percent, more preferred 30 weight percent to 38 weight percent on a dry weight basis based on the total amount of the aerosol-forming substrate. The term “dry weight basis” throughout the application refers to the weight of the aerosol-forming substrate calculated with the water removed via Karl-Fischer titration, for example after being heated to a temperature of 110 degrees Celsius at standard conditions for temperature and pressure and using potentiometry to determine the endpoint. The end point is detected by a bipotentiometric titration method. A second pair of Pt electrodes is immersed in the anode solution. The detector circuit maintains a constant current between the two detector electrodes during titration. Prior to the equivalence point, the solution contains I but little I2. At the equivalence point, excess I2 appears and an abrupt voltage drop marks the endpoint. The amount of charge needed to generate I2 and reach the endpoint can then be used to calculate the amount of water in the original sample. The aerosol-former content can be measured by gas chromatography in combination with a flame ionization detector.

[0039] In certain preferred embodiments, the aerosol-forming substrate may comprise homogenised plant material, preferably a homogenised tobacco material.

[0040] As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-forming substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

[0041] The homogenised plant material can be provided in any suitable form. For example, the homogenised plant material may be in the form of one or more sheets. As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.

[0042] The homogenised plant material may be in the form of a plurality of pellets or granules.

[0043] The homogenised plant material may be in the form of a plurality of strands, strips or shreds. As used herein, the term “strand” describes an elongate element of material having a length that is substantially greater than the width and thickness thereof. The term “strand” should be considered to encompass strips, shreds and any other homogenised plant material having a similar form. The strands of homogenised plant material may be formed from a sheet of homogenised plant material, for example by cutting or shredding, or by other methods, for example, by an extrusion method.

[0044] The tobacco particles may have a nicotine content of at least about 2.5 percent by weight, based on dry weight. More preferably, the tobacco particles may have a nicotine content of at least about 3 percent, even more preferably at least about 3.2 percent, even more preferably at least about 3.5 percent, most preferably at least about 4 percent by weight, based on dry weight.

[0045] At least one susceptor element may be located in the substrate section. In general, the susceptor may comprise or maybe made of a material that is capable of generating heat, when penetrated by an alternating magnetic field. If the susceptor is conductive, then typically eddy currents are induced by the alternating magnetic field. If the susceptor is magnetic, then typically another effect that contributes to the heating is commonly referred to hysteresis losses. Hysteresis losses occur mainly due to the movement of the magnetic domain blocks within the susceptor, because the magnetic orientation of these will align with the magnetic induction field, which alternates. Another effect contributing to the hysteresis loss is when the magnetic domains will grow or shrink within the susceptor. Commonly all these changes in the susceptor that happen on a nano-scale or below are referred to as “hysteresis losses", because they produce heat in the susceptor. Hence, if the susceptor is both magnetic and electrically conductive, both hysteresis losses and the generation of eddy currents will contribute to the heating of the susceptor particles. If the susceptor is magnetic, but not conductive, then hysteresis losses will be the only means by which the susceptor will heat, when penetrated by an alternating magnetic field. An alternating magnetic field generated by one or several induction coils heat the susceptor, which then transfers the heat to the other components of the aerosol-forming substrate. This may facilitate the formation of an aerosol. The heat transfer may be mainly by conduction of heat. The susceptor may be ferromagnetic. The ferromagnetic susceptor may comprise or consist of a metal or metal oxide. The ferromagnetic susceptor may comprise one or more of iron, cobalt and nickel or the oxides thereof. Preferably, the susceptor may comprise or consist of Fe2O3.

[0046] Another embodiment of the invention provides a method for manufacturing an aerosolgenerating article. The article may comprise a ventilation zone with perforations. The method may comprise a method for inspecting the aerosol-generating article for manufacturing defects as described herein.

[0047] During the method of manufacturing, the aerosol-generating article may be transported via a loading drum during method step A) to an inspection drum. The inspection drum may be configured to be employed for the method for inspecting the aerosol-generating article for manufacturing defects as described herein. The perforations may be subjected to light pulses during method step B) while rotating the aerosol-generating article on the inspection drum. A radius of the inspection drum may be larger than a radius of the loading drum.

[0048] This may slow down the transport of the aerosol-generating article on the inspection drum in comparison to the transport on the loading drum. A speed of rotation of the aerosolgenerating article on the inspection drum may be slower than a speed of rotation of the aerosolgenerating article on the loading drum. This may provide more time for the method for inspecting the aerosol-generating article for manufacturing defects. This may improve the accuracy of the method for inspecting for manufacturing defects. Preferably a radius of the inspection drum may be at least 5 times larger than a radius of the loading drum.

[0049] The aerosol-generating article may be accommodated in a rotating hand of the inspection drum. The inspection drum may be rotated in a first direction and the rotating hand may be rotated in a second direction. The first direction of rotation may be opposite to the second direction of rotation. This may serve to slow down the inspection process for manufacturing defects. This may increase the accuracy of the inspection process for detecting manufacturing defects.

[0050] The rotating hands may comprise a rotating spindle including rotating rolls. The rotating hand may be configured to allow a rotation of the aerosol-generating article about its longitudinal axis. This may enable a complete rotation of the aerosol-generating article about its longitudinal axis. This may enable an inspection of all of the perforations in the ventilation zone of the aerosol-generating article for manufacturing defects.

[0051] A first and a second visual inspection system may be applied in one embodiment of the method of the invention. Both the first visual inspection system and the second visual inspection system may comprise a pulsed light source. The pulsed light source may be configured for subjecting the perforations to the light pulses during method step B). Both the first visual inspection system and the second visual inspection system may comprise a light detector. The light detector may be configured for determining any light being reflected by the perforations during method step C).

[0052] Such a first and a second visual inspection system may provide an easy method for applying the light pulses to the perforations and for determining any light being reflected by the perforations.

[0053] The first and the second visual inspection system may be arranged on separate positions around the circumference of the inspection drum. This may enable the inspection of different perforations of the ventilation zone of an aerosol-generating article. These different perforations may be located at different rotational positions on a circumference of the outer wall of the ventilation zone.

[0054] This may enable an easy inspection of perforations being located at different rotational positions of a larger circumference of the ventilation zone.

[0055] The method of manufacturing the aerosol-generating article may be configured for manufacturing a plurality of aerosol-generating articles. The method of manufacturing may be configured as a high-speed manufacturing process. The method of manufacturing may be configured to produce at least 5000 double articles per minute, which is 10.000 individual aerosol-generating articles per minute.

[0056] The method for manufacturing the aerosol-generating article or the plurality of aerosolgenerating articles may comprise an additional method step E) after method step D). This method step E) may comprise changing the parameters for a laser source, the laser source being configured for producing the perforations in the ventilation zone of the article. The parameters of the laser source may be changed in such a way in order to adapt one or more of: the positions of the perforations within the ventilation zone, a width of the perforations within the perforation zone, a depth of the perforations within the perforation zone and a number of perforations within the perforation zone in order to change the intensity of reflected light detected in method step C). This may assist in reducing or avoiding any deviation from a reference range of the intensity of the reflected light determined in method step D). This may enable to change the parameters of the laser source in such a way so that the perforations produced conform with the required specifications for perforations without manufacturing defects.

[0057] At the beginning of the manufacturing process for the aerosol-generating articles, the laser source may be calibrated on a reference value of the reflected light detected in method step C) being 0. This may correspond to the intensity of reflected light being expected to be received from a perforation without any manufacturing defects. If an intensity of reflected light outside of the reference range is detected in method step C) during the manufacturing process, the duty cycle of the laser source may be adjusted within a range of 50 percent to 90 percent. The duty cycle may be calculated as (pulse width of laser source) / (pulse period of laser source)* 100. The duty cycle may in particular be adjusted by keeping the power of the laser source constant and taking the speed of the manufacturing equipment into consideration. This may reduce the manufacturing defects of the perforations in the ventilation zone.

[0058] In particular, the higher the intensity of reflected light outside of the reference range detected in method step C), the higher may be the increase in the duty cycle of the laser source. Once the intensity of reflected light detected in method step C) is within the reference range, the duty cycle of the laser source may be reduced, accordingly.

[0059] Another embodiment of the invention provides an inspection apparatus. The inspection apparatus may be configured for carrying out a method for inspecting an aerosol-generating article for manufacturing defects as described herein. The inspection apparatus may comprise a first visual inspection system. The inspection apparatus may comprise a second visual inspection system. The first visual inspection system may comprise a first pulsed light source. The first pulsed light source may be configured for subjecting the perforations to the light pulses during method step B) The first visual inspection system may comprise a first light detector. The first light detector may be configured for determining any light being reflected by the perforations during method step C). The second visual inspection system may comprise a second pulsed light source. The second pulsed light source may be configured for subjecting the perforations to the light pulses during method step B). The second visual inspection system may comprise a second light detector. The second light detector may be configured for determining any light being reflected by the perforations during method step C). The inspection apparatus may comprise an inspection unit configured for carrying out method step D). The inspection unit for example may comprise computational means for determining whether any reflected light detected by the light detectors is within a reference range or outside a reference range.

[0060] A further embodiment of the invention provides an inspection apparatus configured for carrying out a method of inspection as described herein. The inspection apparatus comprises a first visual inspection system and a second visual inspection system. The first visual inspection system comprises a first pulsed light source and a first light detector. The second visual inspection system comprises a second pulsed light source and a second light detector. The first pulsed light source and the second pulsed light source are both configured for subjecting the perforations to the light pulses during method step B). The first light detector and the second light detector both are configured for determining any light being reflected by the perforations during method step C). The inspection apparatus furthermore comprises an inspection control unit configured for carrying out method step D).

[0061] Such an inspection apparatus may ease the inspection of the aerosol-generating articles for manufacturing defects. The aerosol-generating article produced by the method of the present invention may be used in an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating article as described herein and an aerosol-generating device comprising a cavity for receiving the aerosol-generating article.

[0062] Such an aerosol-generating system comprising the aerosol-generating article and the aerosol-generating device may be configured to provide an aerosol from the aerosol-forming substrate of the substrate section of the aerosol-generating article as described herein.

[0063] The cavity of the aerosol-generating device may comprise inner walls with sections protruding inwards into the cavity. These protruding sections may contact the aerosolgenerating article received in the cavity. These protruding sections may allow the formation of an air flow path between the inner walls of the cavity and the aerosol-generating article. This may also allow the formation of an airflow path leading to the above-described ventilation zone of the aerosol-generating article.

[0064] The aerosol-generating device may include a heating element, in particular an inductive heating element, such as an inductive coil. Upon inductive heating of the aerosol-forming substrate of the aerosol-generating article received in the aerosol-generating device, the susceptor may be heated by the alternating magnetic field of the inductive heating element. This may also heat the aerosol-forming substrate. For induction heating, the heating element preferably comprises an induction coil. An alternating current may be supplied to the induction coil for generating an alternating magnetic field. The alternating current may have a high frequency. As used herein, the term "high frequency oscillating current" means an oscillating current having a frequency of between 500 kilohertz and 30 megahertz. The high frequency oscillating current may have a frequency of from about 1 megahertz to about 30 megahertz, preferably from about 1 megahertz to about 10 megahertz and more preferably from about 5 megahertz to about 8 megahertz.

[0065] The heating element may be configured to heat the aerosol-generating article to a temperature ranging from 220 degrees Celsius to 400 degrees Celsius, preferably from 250 degrees Celsius to 290 degrees Celsius. The heating element may be configured to heat the aerosol-generating article, in particular the aerosol-forming substrate to a temperature below the combustion temperature of the aerosol-forming substrate. This may allow the use of an aerosol generated from a “heat not burn” aerosol-generating article.

[0066] The heating element may be configured as a resistive heating element. The heating element may be configured as a resistive heating coil, at least partly surrounding the cavity, for receiving the aerosol-generating article.

[0067] The heating element may be located adjacent to the cavity for receiving the aerosolgenerating article. The heating element may be located at least partly around the cavity for heating an aerosol-generating article received in the cavity. The heating element may surround a perimeter of the cavity for receiving the aerosol-generating article. This may allow a reliable and uniform heating of the substrate section of the aerosol-generating article.

[0068] Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0069] Example Ex1 : Method for inspecting an aerosol-generating article for manufacturing defects, the method comprising the method steps:

[0070] A) providing the aerosol-generating article comprising a ventilation zone with perforations, the article furthermore comprising a longitudinal axis,

[0071] B) subjecting the perforations to light pulses while rotating the aerosol-generating article about the longitudinal axis,

[0072] C) determining any light being reflected by the perforations, and

[0073] D) assessing based on the reflected light whether a manufacturing defect is present in the perforations of the ventilation zone.

[0074] Example Ex2: Method for inspecting according to the preceding example, wherein during method step D) the reflected light determined in method step C) is compared to a reference range for the reflected light.

[0075] Example Ex3: Method for inspecting according to any of the preceding examples, wherein an intensity of the reflected light indicates a manufacturing defect, preferably wherein a lack of reflected light indicates a correct perforation without manufacturing defect.

[0076] Example Ex4: Method for inspecting according to any of the preceding examples, wherein a number of perforations is arranged in an outer wall of the ventilation zone and wherein the light pulses applied in method step B) are at least partly reflected in method step C) by one or both of: parts of the outer wall being located adjacent to the perforations or parts of the outer wall being located within the perforations.

[0077] Example Ex5: Method for inspecting according to any of the preceding examples, wherein the ventilation zone is circumscribed by a light reflective wrapper and wherein the light pulses applied in method step B) are at least partly reflected in method step C) by parts of the light reflective wrapper being located adjacent to the perforations.

[0078] Example Ex6: Method for inspecting according to any of the preceding examples Ex4 or Ex5, wherein one or both: an area of the outer wall reflecting the light pulses and an area of the light reflective wrapper reflecting the light pulses increases with an increase of a manufacturing defect.

[0079] Example Ex7: Method for inspecting according to any of the preceding examples, wherein a number of perforations is arranged in an outer wall of the ventilation zone, each of the perforations having an actual width extending between opposing side walls of the outer wall, an actual depth extending from the exterior of the outer wall through the outer wall towards the interior of the aerosol-generating article and an actual position on the circumference of the outer wall, and wherein an intensity of reflected light indicates one or more of: a deviation of the actual width from a correct width, a deviation of the actual depth from a correct depth, a deviation of the actual position from a correct position of the perforation and a deviation of the actual number of perforations from a correct number of perforations.

[0080] Example Ex8: Method for inspecting according to the preceding example, wherein in method step C) an intensity of the reflected light increases, if one or more of: a deviation of the actual width from the correct width increases, a deviation of the actual depth from the correct depth increases and a deviation of the actual position from the correct position increases.

[0081] Example Ex9: Method for inspecting according to any of the preceding examples, wherein the perforations are arranged in an outer wall of the ventilation zone, wherein the outer wall comprises a light reflective material, preferably wherein the light reflective material comprises one or more materials selected from the group consisting of: cellulose acetate; cardboard; crimped paper, and polymeric materials.

[0082] Example Ex10: Method for inspecting according to any of the preceding examples, wherein the ventilation zone is circumscribed by a light reflective wrapper, preferably a paper wrapper or a cardboard wrapper.

[0083] Example Ex11 : Method for inspecting according to any of the preceding examples Ex9 or Ex10, wherein the reflected light detected in method step C) is reflected from one or both: the light reflective wrapper and the light reflective material of the outer wall of the ventilation zone.

[0084] Example Ex12: Method for inspecting according to any of the preceding examples, wherein the perforations are arranged in an outer wall of the ventilation zone, each of the perforations comprising a central longitudinal perforation axis, the aerosol-generating article furthermore comprising a central longitudinal article axis, wherein a number of perforations are located at different rotational positions on a circumference of the outer wall, the different rotational positions corresponding to different rotation angles of each central longitudinal perforation axis with regard to the central longitudinal article axis, preferably wherein the light pulses are applied at the respective different rotational positions of the perforations.

[0085] Example Ex13: Method for inspecting according to any of the preceding examples, wherein during method step B) Xenon light pulses or LED light pulses are applied.

[0086] Example Ex14: Method for inspecting according to any of the preceding examples, wherein the aerosol-generating article is a continuous double article being made of two aerosol-generating articles, each article comprising a ventilation zone with perforations, preferably wherein method steps B) to C) are applied to each of the ventilation zones simultaneously. Example Ex15: Method for manufacturing an aerosol-generating article comprising a ventilation zone with perforations, comprising a method for inspecting the aerosol-generating article for manufacturing defects according to any of the preceding examples.

[0087] Example Ex16: Method for manufacturing according to the preceding example, wherein the aerosol-generating article is transported via a loading drum during method step A) to an inspection drum and wherein the perforations are subjected to light pulses while rotating the aerosol-generating article on the inspection drum, wherein a radius of the inspection drum is larger than a radius of the loading drum, preferably wherein a radius of the inspection drum is at least 5 times larger than a radius of the loading drum.

[0088] Example Ex17: Method for manufacturing of the preceding example, wherein the aerosol-generating article is accommodated in a rotating hand of the inspection drum, wherein the inspection drum is rotated in a first direction and wherein the rotating hand is rotated in a second direction, the first direction of rotation being opposite to the second direction of rotation.

[0089] Example Ex18: Method for manufacturing of any of the preceding examples, wherein a first and a second visual inspection system are applied, the first and second visual inspection system both systems comprising a pulsed light source configured for subjecting the perforations to the light pulses during method step B) and a light detector configured for determining any light being reflected by the perforations during method step C).

[0090] Example Ex19: Method for manufacturing an aerosol-generating article of the preceding example, further being dependent on any of the examples Ex16 or Ex17, wherein the first and second visual inspection system are arranged on separate positions around the circumference of the inspection drum for inspecting different perforations of the ventilation zone.

[0091] Example Ex20: Inspection apparatus configured for carrying out a method for inspection of any of the examples Ex1 to Ex14, comprising

[0092] - a first visual inspection system and a second visual inspection system,

[0093] - the first visual inspection system comprising a first pulsed light source and a first light detector, and the second visual inspection system comprising a second pulsed light source and a second light detector,

[0094] - the first pulsed light source and the second pulsed light source both being configured for subjecting the perforations to the light pulses during method step B) and the first light detector and the second light detector both being configured for determining any light being reflected by the perforations during method step C), and

[0095] - an inspection control unit configured for carrying out method step D).

[0096] Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

[0097] The invention will be further described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 shows a cross-sectional view of a continuous double article, including two aerosol-generating articles;

[0098] Fig. 2 depicts a cross-sectional view of an inspection apparatus configured for carrying out an embodiment of an inspection method in accordance with the present invention;

[0099] Fig. 3 shows a photograph of a perforation produced by a laser light source, and

[0100] Fig. 4 shows a cross-sectional view of an aerosol-generating article through the ventilation zone depicting different perforations which are either without a manufacturing defect or showing different manufacturing defects.

[0101] In the following elements with the same functionality are marked with the same reference numerals throughout all the figures.

[0102] Fig. 1 depicts a schematic cross-sectional view of a first continuous double article 11 including two separate individual first aerosol-generating articles 10, thereby forming a double stick. Such a double stick may be employed by an embodiment of the method for inspecting the aerosol-generating article for manufacturing defects. These individual aerosol-generating articles 10 can be generated from the first continuous double article 11 by cutting the continuous rod along the dashed line 10A. The two individual aerosol-generating articles 10 are connected to each other via their respective mouth end filter elements 20. These mouth end filter elements 20 are adjacent to the hollow tube section 14, which consists of the hollow support element 16 and the aerosol-cooling element 18. This hollow tube section 14 is adjacent to the substrate section 22 in the individual aerosol-generating articles 10, wherein each substrate section 22 contains a susceptor 24. This substrate section 22 is flanked in each aerosol-generating article by the filter element 26. In the continuous rod two ventilation zones 12 are present in the hollow tube sections 14 of each individual aerosol-generating article 10. The method for inspecting the aerosol-generating article for manufacturing defects allows to simultaneously inspect the perforations of both ventilation zones 12 in the continuous rod for manufacturing defects.

[0103] The length of such a double stick may be 90 millimeters. Consequently, the length of the individual aerosol-generating articles after cutting of the double stick may be 45 millimeters. The diameter of the double stick may be 7.25 mm.

[0104] Fig. 2 depicts a schematic view of an inspection apparatus 50 configured for carrying out an inspection method for manufacturing defects in accordance with an embodiment of the present invention. The inspection apparatus 50 comprises a first visual inspection system 37, a second visual inspection system 36, an inspection control unit 38 and an inspection drum 34 for transporting the aerosol-generating article through the inspection process. The inspection apparatus 50 is integrated in a manufacturing process for manufacturing the aerosolgenerating articles and allows a quick change of the settings for producing the perforations within the ventilation zone in order to reduce or avoid manufacturing defects. On the right-hand side of Fig. 2, a first manufacturing drum 28 is shown which rotates in a rotation direction 28A. The first manufacturing drum 28 transports aerosol-generating articles 11 A, which do not include the perforations of the ventilation zone to the first loading drum 29 with the direction of rotation 29A. This first loading drum 29 transports the aerosol-generating articles 11A without ventilation zone to a second manufacturing drum 30. In the center of the second manufacturing drum 30 a laser light source 32 for producing the perforations is located. The second manufacturing drum 30 includes rotating hands 31 which allow the rotation of the aerosolgenerating article about it central longitudinal axis while the laser light source 32 forms the perforations in the aerosol-generating articles 11. The laser light source 32 is controlled by the laser light source control unit 39. The inspection control unit 38 of the inspection apparatus 50 is also connected to the laser light source control unit 39 and is configured in order to control the laser light source control unit 39 based on the outcome of the inspection in method step D). The finished double article aerosol-generating articles 11 with the ventilation zones are transported from the second manufacturing drum to the second loading drum 33 with the direction of rotation 33A. This second manufacturing drum transports the aerosol-generating articles 11 to the inspection drum 34 of the inspection apparatus 50. A radius of the inspection drum 34 is larger than a radius of the second loading drum 33. This enables to slow down the inspection process, increasing the accuracy of the inspection process for manufacturing defects. The inspection drum 34 includes rotating hands (rotating hands not shown in Fig. 2) which rotate the aerosol-generating articles 11 about their central longitudinal axis in a rotation direction opposite to the direction of rotation 34A of the inspection drum 34. This additionally slows down the inspection process. The first visual inspection system 37 includes a first pulsed light source and a first light detector and the second visual inspection system 36 includes a second pulsed light source and a second light detector (pulsed light sources and light detectors not individually shown in Fig. 2). The first visual inspection system 37 and the second visual inspection system 36 are arranged on separate positions around the circumference of the inspection drum 34. This enables both visual inspection systems to inspect different perforations on a circumference of the ventilation zone. The inspected aerosol-generating articles 11 can be transported to an unloading drum 35 with the rotation direction 35A. These inspected aerosol-generating articles 11 can either be discarded in the case that they are not within the specification required for a ventilation zone without manufacturing defects or can be transported to a further manufacturing section where the continuous double article is cut in order to produce individual aerosol-generating articles. Depending on the outcome of the inspection method for manufacturing defects, the inspection control unit 38 of the inspection apparatus 50 can change the settings of the laser light source control unit 39 for changing the parameters for generating the perforations in the ventilation zone with the laser light source 32. Fig. 3 shows a photograph of a perforation 12A with the expected boundaries for correct perforation shown in dashed lines 12B. This photograph shows that a perforation 12A in accordance with the specifications for a correct perforation would absorb most of the light applied by the light pulses in method step B) so that no or only little intensity of reflected light would be detected in method step C).

[0105] Fig. 4 depicts a schematic cross-sectional view of an aerosol-generating article 11 through one of its ventilation zones 12. Fig. 4 shows that the hollow section of the ventilation zone includes a light reflective material 18 of an outer wall of the ventilation zone which is circumscribed by a light reflective wrapper 40. Four different perforations 12A are located at four different rotational positions with regard to a central longitudinal axis 43 of the aerosolgenerating article 11 . The expected, correct central longitudinal perforation axis for each of the perforations 12A are indicated with dashed lines 44. The arrows indicated with the reference signs 41 A, 41 B, 41 C and 41 D indicate the direction of the light pulses applied to the sections where a perforation 12A without manufacturing defects would be expected to be located. The dashed lines 12B indicate the expected boundaries of a perforation 12A without manufacturing defects. The perforation 12A in the upper part of Fig. 4 exhibits a correct expected width 12D between opposing sidewalls of the perforation and a correct expected depth 12C of the perforation leading from outside of the ventilation zone into the interior of the aerosolgenerating article 11. With such a perforation 12A extending within the expected correct boundaries 12B no or only a very small intensity of reflected light is to be expected to be detected in method step C) when a light pulse 41 A is applied to the perforation 12A along the central longitudinal axis 44 of the perforation 12A.

[0106] The perforation 12A shown on the left-hand side of Fig. 4 is slightly tilted with regard to the expected, correct boundaries 12B. This manufacturing defect results in additional intensity of reflected light. In particular, a light pulse 41 D applied along the expected central longitudinal perforation axis 44 results in light being reflected at parts of the light reflective wrapper 40 and of the light reflective material 18 as indicated with the arrows denoted with the reference signs 42D. This perforation 12A shows an actual width 12B’ between opposing sidewalls of the perforation which differs from the expected, correct width 12D, resulting in an increased intensity of reflected light.

[0107] The perforation 12A shown in the lower half of Fig. 4 is an incomplete perforation so that light reflective material 18 of the outer wall is located within the perforation. This light reflective material leads to light being reflected as indicated by the arrow with the reference sign 42C when a light pulse 41 C is applied along the central longitudinal perforation axis 44. This perforation 12A has a depth 12C’ which differs from the expected, correct depth 12C, as shown above. The perforation 12A shown in the right-hand part of Fig. 4 shows an offset with regard to the expected boundaries 12B for a correct perforation 12A and is laterally displaced in comparison to a perforation without manufacturing defects. When a light pulse 41 B is applied to that perforation additional intensity of reflected light from the light reflective wrapper 40 can be detected as indicated by the arrow denoted with 42B.

Claims

1. A method for testing an aerosol-generating product for the presence of manufacturing defects, which method includes the following steps: A) providing an aerosol generating article comprising a ventilation zone with perforations, wherein the article further comprises a longitudinal axis, B) exposure to light pulses on the perforation holes during rotation of the aerosol-generating article around the longitudinal axis, wherein at step B) of the method the light pulses are applied at a frequency that allows the light to affect the positions of the perforation holes within the ventilation zone, C) determination of any light reflected by the perforations, and D) assessing, based on reflected light, whether a manufacturing defect is present in the perforations of the ventilation zone.

2. The verification method according to claim 1, characterized in that during step D) of the method, the reflected light determined in step C) of the method is compared with a reference range for reflected light.

3. A method of testing according to any of the preceding claims, characterized in that the intensity of the reflected light indicates a manufacturing defect, while preferably the absence of reflected light indicates a proper perforation hole without manufacturing defects.

4. A testing method according to any of the preceding claims, characterized in that a number of perforations are located in the outer wall of the ventilation zone, and wherein the light pulses applied in step B) of the method are at least partially reflected in step C) of the method by one or both of: parts of the outer wall located adjacent to the perforations, or parts of the outer wall located inside the perforations.

5. A testing method according to any of the preceding claims, characterized in that the ventilation zone is surrounded by a reflective wrapping, and wherein the light pulses applied in step B) of the method are at least partially reflected in step C) of the method by parts of the reflective wrapping located adjacent to the perforation holes.

6. The testing method according to paragraph 4 or 5, characterized in that one or both of: the area of ​​the outer wall reflecting light pulses and the area of ​​the reflective wrapper reflecting light pulses increase with the increase of the manufacturing defect.

7. A testing method according to any of the preceding claims, characterized in that a number of perforations are located in the outer wall of the ventilation zone, wherein each of the perforations has an actual width extending between opposite side walls of the outer wall, an actual depth extending from the outer portion of the outer wall through the outer wall in the direction of the interior of the aerosol-generating article, and an actual position on the circumference of the outer wall, and wherein the intensity of reflected light indicates one or more of: a deviation of the actual width from the proper width, a deviation of the actual depth from the proper depth, a deviation of the actual position from the proper position of the perforation, and a deviation of the actual number of perforations from the proper number of perforations.

8. The testing method according to the previous paragraph, characterized in that in step C) of the method the intensity of the reflected light increases if one or more of: the deviation of the actual width from the proper width, the deviation of the actual depth from the proper depth, and the deviation of the actual position from the proper position increases.

9. A testing method according to any of the preceding paragraphs, characterized in that the perforation holes are located in the outer wall of the ventilation zone, wherein the outer wall contains a reflective material, preferably wherein the reflective material contains one or more materials selected from the group consisting of: cellulose acetate; cardboard; corrugated paper and polymeric materials.

10. A testing method according to any of the preceding paragraphs, characterized in that the ventilation zone is surrounded by reflective wrapping, preferably paper wrapping or cardboard wrapping.

11. The testing method according to claim 9 or 10, characterized in that the reflected light recorded in step C) of the method is reflected from one or both of: the reflective wrapper and the reflective material of the outer wall of the ventilation zone.

12. A testing method according to any of the preceding paragraphs, characterized in that in step B) of the method, a plurality of perforations in the ventilation zone are tested for the presence of manufacturing defects by exposing different perforations in the same ventilation zone of the aerosol-generating article to light pulses while rotating the same aerosol-generating article.

13. A method for producing an aerosol-generating article comprising a ventilation zone with perforations, including a method for testing the aerosol-generating article for the presence of manufacturing defects according to any of the preceding paragraphs.

14. The production method according to claim 13, characterized in that the aerosol-generating article is transported by means of a loading drum during step A) of the method onto an inspection drum, and wherein the perforations are exposed to light pulses during rotation of the aerosol-generating article on the inspection drum, wherein the radius of the inspection drum is greater than the radius of the loading drum, preferably wherein the radius of the inspection drum is at least 5 times greater than the radius of the loading drum.

15. The manufacturing method according to the previous paragraph, characterized in that the aerosol-generating article is placed in a rotating grip of the testing drum, wherein the testing drum is rotated in a first direction, and wherein the rotating grip is rotated in a second direction, wherein the first direction of rotation is opposite to the second direction of rotation.

16. A testing device configured to implement the testing method according to any one of paragraphs 1-12, comprising - the first visual inspection system and the second visual inspection system, - wherein the first visual inspection system comprises a first pulsed light source and a first light sensor, and the second visual inspection system comprises a second pulsed light source and a second light sensor, - wherein both the first pulsed light source and the second pulsed light source are configured to act on the perforation openings with light pulses during step B) of the method with a frequency that allows the light to act on the positions of the perforation openings within the ventilation zone, and wherein both the first light sensor and the second light sensor are configured to detect any light reflected by the perforation openings during step C) of the method, and - a verification control unit configured to implement step D) of the method.