WO2024002982A1

WO2024002982A1 - Taggant inspection system

Info

Publication number: WO2024002982A1
Application number: PCT/EP2023/067347
Authority: WO
Inventors: Hans-Reiner Hoffmann; Markus Brand; Walter Braumandl; Helmut LÖW
Original assignee: Philip Morris Products S.A.
Priority date: 2022-06-29
Filing date: 2023-06-26
Publication date: 2024-01-04

Abstract

There is provided a system for checking taggant applied to components of aerosol- generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the system comprising: at least one first sensor configured to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; and at least one second sensor located downstream of the at least one first sensor on the manufacturing line, the at least one second sensor configured to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

Description

TAGGANT INSPECTION SYSTEM

The present disclosure relates to a system and method for checking quality parameters of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line.

Aerosol-generating devices which heat an aerosol-forming substrate to produce an aerosol without burning the aerosol-forming substrate are known in the art. The aerosolforming substrate is typically provided within an aerosol-generating article, together with other components such as one or more filter segments. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a cavity of the aerosol-generating device.

A heating element is typically arranged to heat the aerosol-forming substrate once the aerosol-generating article is inserted into the cavity of the aerosol-generating device. The heating element may comprise an internal heating element that extends into the cavity and is received in the aerosol-generating article. The heating element may comprise an external heating element arranged to extend around the outside of the aerosol-generating article. The combination of the aerosol-generating device and the aerosol-generating article may be referred to as an aerosol-generating system.

Aerosol-generating articles developed for use in an aerosol-generating system are typically specially designed, because the flavours are generated and released by a controlled heating of the aerosol-forming substrate, without the combustion that takes place in lit-end cigarettes and other smoking articles. Therefore, the structure of the aerosol-generating article may be different from the structure of a lit-end smoking article. Using a lit-end smoking article with an aerosol-generating device may result in a poor smoking experience for the user, and may also damage the aerosol-generating device because, for example, the smoking article is not compatible with the aerosol-generating device.

Nonetheless, it is conceivable that a user may, inadvertently or otherwise, attempt to use an aerosol-generating article with an aerosol-generating device where the device is not designed to be used with the article. For example, a user may attempt to use a lit-end cigarette, or a counterfeit aerosol-generating article in an aerosol-generating device. This may result in poor aerosol-generation and reduced user experience which may reflect badly on the aerosol-generating device. In addition, the use of aerosol-generating articles other than those intended may damage the aerosol-generating device.

In addition, there may be a number of different aerosol-generating articles which are each configured for use with the aerosol-generating device, but which each provide a different smoking experience for the user. It may be desirable for one of more heating elements of the aerosol-generating device to reach different temperatures at different times (that is, have a different heating profile) depending on the variety or flavour of aerosol-generating article used with the aerosol-generating device. In such examples, it would be desirable for the aerosolgenerating device to alter the temperature settings automatically without a user needing to enter any details manually.

It would be desirable to provide an aerosol-generating article, an aerosol-generating device and an aerosol-generating system that facilitates detection of the presence of particular aerosol-generating articles. Where the aerosol-generating device does not recognise a particular aerosol-generating article, it would be desirable to prevent activation of a heating element to prevent a poor user experience. In addition, where the aerosol-generating device detects a particular recognised aerosol-generating article, it would be desirable for the aerosolgenerating device to operate a heating element according to a particular heating profile configured specifically for use with that variety of aerosol-generating article.

It is known to address these problems by applying a taggant to at least a component of an aerosol-generating article. The taggant may be a photoluminescent taggant that generates an identifiable signal when exposed to electromagnetic radiation of particular wavelengths.

An aerosol-generating system may comprise an emitter to emit electromagnetic radiation towards the taggant on the aerosol-generating article and a receiver to receive electromagnetic radiation emitted by the taggant in response to the incident electromagnetic radiation. In this way, the aerosol-generating device can identify an aerosol-generating article inserted into the device by checking for a predetermined photoluminescent profile generated by the taggant in response to incident electromagnetic radiation. Different taggants with different photoluminescent profiles can be used to identify different flavours, strengths or types of aerosol-generating articles, and this information can be used to set appropriate operational parameters, such as heating parameters, for the aerosol-generating device. It is also possible to prevent the use of counterfeit aerosol-generating articles, or aerosol-generating articles not designed for use with a particular aerosol-generating device, by preventing heating operation if the predetermined photoluminescent profile is not detected.

Applying taggant to aerosol-generating articles during manufacture can be complex, and it is important for quality parameters of the applied taggant to be within predetermined tolerances. If, for example, taggant is insufficiently applied or not applied to a sufficient degree of continuity (for example, with no interruptions greater than 1 millimetre (mm)), this may result in genuine aerosol-generating articles being manufactured and sold, but not able to be used in genuine aerosol-generating devices, which can result in consumer disappointment. Furthermore, because of the high speed and throughput of manufacturing processes for aerosol-generating articles (typically several thousand articles per minute), there is insufficient time to perform a full taggant quality check for each individual article without appreciably slowing down the manufacturing process and increasing costs.

According to an aspect of the present invention, there is provided a system for checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the system comprising: at least one first sensor configured to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; and at least one second sensor located downstream of the at least one first sensor on the manufacturing line, the at least one second sensor configured to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

The present invention employs two different types of sensor, each performing a different function.

The at least one first sensor is provided at an upstream location relative to the at least one second sensor, and is configured to detect the taggant applied to the surface of the material web. Advantageously, the material web is in the form of a continuous band of material, such as tipping paper, that is unwound from a spool of material. The taggant may be applied by spraying or painting a taggant solution onto the surface of the material web so as to form at least one substantially continuous line along a length of the continuous band. The at least one first sensor may be configured to detect the presence of the taggant and to verify that the taggant is applied to meet a predetermined continuity of application quality condition along a length of the band of the material web. Alternatively or in addition, the at least one first sensor may be configured to detect interruptions in the substantially continuous line or lines of taggant applied to the continuous band or to detect a variation in the amount of taggant per unit length of the band of the material web. If an interruption is detected, or if the variation in the amount of taggant per unit length outside of permitted tolerances is detected, then a fault condition may be indicated. If a fault condition is indicated, the manufacturing process may be stopped until the cause of the fault is determined and fixed. Alternatively or in addition, aerosol-generating articles manufactured with portions of the material web where the taggant does not meet the predetermined continuity of application quality condition may be automatically discarded by the manufacturing line. Importantly, the at least one first sensor may be configured to detect only the presence and the continuity of application quality condition of the taggant on the surface of the material web. The at least one first sensor does not need to identify a photoluminescent profile of the taggant. This can speed up the manufacturing process, since the band of material web can be run past the at least one first sensor at a greater speed than would be possible if it were necessary also to identify the photoluminescent profile of the taggant.

The at least one second sensor is provided at a downstream location relative to the at least one first sensor, and is configured to confirm at least one of the photoluminescent profile of the taggant and a concentration of the taggant. The at least one second sensor is configured to inspect the taggant on individual portions of the material web after the portions have been cut from the continuous band of material web. The cut portions may be configured as circumferential wrappers in rod-shaped articles, such as components of aerosol-generating articles. Because the at least one first sensor has already established that the taggant has been applied to meet a predetermined continuity of application quality condition along the band of the material web, the at least one second sensor does not need to check the taggant continuity for each cut portion of the material web, either before or after the cut portion of the material web is formed into a circumferential wrapper. Instead, the at least one second sensor is configured to confirm at least one of the photoluminescent profile of the taggant and the concentration of the taggant. This step can take a finite amount of time for each rod-shaped article. This step can take a longer time than the step of detecting the taggant applied to the surface of the material web and determining that the taggant has been applied to meet the predetermined continuity of application quality condition. By removing the need to check for continuity of taggant application on the cut portions of the material web, the system of the present invention means that only a relatively small portion of the taggant on the cut portion of the material web needs to be inspected by the at least one second sensor, since the at least one first sensor has already established that taggant has been applied to a required degree of continuity, for example with no interruptions greater than 1 millimetre. As a result, more time is available for the at least one second sensor to identify and confirm the photoluminescent profile of the taggant for a given throughput of cut portions of the band of material web.

Moreover, in some manufacturing lines, the material web, before it is cut into portions, may travel at high speeds, for example 120 to 150 m/min. In examples where the material web is travelling at 125 m/min, a movement of 1mm takes place every 480 microseconds (ps). It can take several milliseconds (ms), for example about 2ms, to confirm a photoluminescent profile of a taggant (there needs to be enough time for the taggant to absorb and re-emit photonic energy and for a detector to perform calculations in order to analyse and identify the photoluminescent profile), and this means that it is very difficult to confirm a photoluminescent profile of a taggant at high material web travel speeds. Reducing the travel speed of the material web so as to allow the photoluminescent profile of the taggant to be confirmed can result in a significant reduction in production speed.

By separating the sensor that checks taggant continuity from the sensor that confirms at least one of the predetermined profile of the taggant and the predetermined concentration of the taggant, a high degree of taggant application quality control is made possible without compromising on the speed and efficiency of the manufacturing line. The first sensor is configured to perform the function of detecting the taggant applied to the surface of the material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition, which can be done at relatively high material web travel speeds. Accordingly, the first sensor can be disposed at a part of the manufacturing line where the material web is travelling at a high speed. The second sensor is configured to perform the function of confirming at least one of the predetermined profile of the taggant and the predetermined concentration of the taggant, which takes longer than determining the continuity of application quality condition. Accordingly, the second sensor is disposed at a part of the manufacturing line where the material web is not travelling at such high speed, namely after the material web has been cut into portions (for example to form circumferential wrappers in rod-shaped articles).

In some embodiments, the at least one first sensor is disposed at an upstream part of the system where the material web, in the form of a band of material, travels past the at least one first sensor at a velocity of at least 50 m/min. In some embodiments, the at least one first sensor is disposed at an upstream part of the system where the material web, in the form of a band of material, travels past the at least one first sensor at a velocity of at least 100 m/min.

In some embodiments, the at least one second sensor is disposed at a downstream part of the system where cut portions of the material web travel past the at least one second sensor at a velocity of less than 50 m/min. For example, the at least one second sensor may be disposed a downstream part of the system where the cut portions of material web have been wrapped around various components to form rod-shaped articles, and the rod-shaped articles are being transported around a circumference of a drum-shaped transfer assembly having a plurality of longitudinally-extending circumferential channels. The drum-shaped transfer assembly may rotate at a speed of up to around 140 revolutions per minute (rpm). The drumshaped transfer assembly may rotate at a speed of up to around 180rpm. In some examples, a rotational speed of 143rpm results in passage of 4000 rod-shaped articles per minute passing the second sensor. In some examples, a rotational speed of 178rpm results in passage of 5000 rod-shaped articles per minute passing the second sensor. In some examples, it may take about 10 to 12ms for the drum-shaped transfer assembly to rotate by an angle subtended by a distance of a separation between one longitudinally-extending circumferential channel to an adjacent longitudinally-extending circumferential channel.

The material web may be tipping paper.

The material web may be a band of material having a length that is at least 1000 times greater than a width of the band of material. For example, the band of material may be unwound from a bobbin of material web. For example, the band of material may have a width of 40mm to 100mm, and a length of over 2500m, for example of 2500m to 3400m.

The taggant may be applied to the material web in the form of at least one substantially continuous band along the length of the material web. In some embodiments, the taggant is applied to the material web in the form of at least two substantially continuous bands of taggant along the length of the material web. Having at least two substantially continuous bands applied generally in parallel along the length of the material web allows the material web firstly to be cut into tipping paper portions configured for forming conjoined pairs of rod-shaped articles, namely forming double-length rod-shaped articles, which can then be cut in a direction perpendicular to a longitudinal axis of the conjoined pair of rod-shaped articles to form two individual rod-shaped articles. The application of two substantially continuous bands of taggant along the length of the material web means that each individual rod-shaped article, after cutting, can be provided with a band of taggant on the tipping paper.

The first sensor may be configured to indicate a fault condition if the first sensor detects a variation outside a predetermined range in the amount of taggant per unit length applied along the at least one substantially continuous band or in the amount of taggant per unit length applied along at least one of the at least two substantially continuous bands. For example, the first sensor may be configured to indicate a fault condition if the first sensor detects an interruption of greater than 1 mm along the length of the band or bands of taggant. The first sensor thus determines if the taggant applied along the at least one substantially continuous band or applied along at least one of the at least two substantially continuous bands has been applied to meet a predetermined continuity of application condition. For example, in the event that the application of taggant by a taggant applicator is interrupted due to nozzle blockage or depletion of a reservoir of taggant, the at least one first sensor can provide a quick indication that the taggant applicator requires attention or maintenance.

The cut portions of the material web may be configured as circumferential wrappers in rod-shaped articles. For example, a machine known in the art as a combiner can be used to combine several components into a single or double rod-shaped article by circumferentially wrapping several aligned components in a portion of tipping paper.

The taggant may be present on exterior surfaces of the circumferential wrappers. For example, the taggant may be applied to a surface of the material web that will form an exterior tipping paper surface on a finished rod-shaped article. This facilitates identification of the rodshaped article in an aerosol-generating device by illuminating the exterior surface of the tipping paper with light of a predetermined wavelength when the rod-shaped article is inserted into a cavity of an aerosol-generating device, since the light will not have to penetrate the tipping paper in order to elicit a photoluminescent response from the taggant.

Alternatively or in addition, the taggant may be present on interior surfaces of the circumferential wrappers. For example, the taggant may be applied to a surface of the material web that will form an interior tipping paper surface on a finished rod-shaped article. Although this could potentially reduce the sensitivity of identification of the rod-shaped article in an aerosol-generating device, provision of taggant on interior surfaces of the circumferential wrappers may help to avoid or reduce erosion of taggant from the tipping paper during transport or handling of the rod-shaped articles prior to insertion into an aerosol-generating device.

The second sensor may be configured to inspect each circumferential wrapper at only one rotational orientation of the rod-shaped article with respect to a longitudinal axis of the rod-shaped component. For example, where the rod-shaped articles (whether single rodshaped articles or double conjoined rod-shaped articles) are being transported around a circumference of a drum-shaped transfer assembly having a plurality of longitudinally extending circumferential channels, the rod-shaped articles need not themselves rotate within the circumferential channels. Because the first sensor has already determined that the taggant has been applied to meet a predetermined continuity of application condition, there is no need for the second sensor to perform the same check. It can be assumed by the second sensor that the taggant has been applied to meet the predetermined continuity of application condition, and the second sensor can therefore be configured just to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant by inspecting the taggant at a single rotational orientation of the rod-shaped article with respect to a longitudinal axis of the rod-shaped component.

The first sensor or the second sensor or the first sensor and the second sensor may be configured to operate using electromagnetic waves having a wavelength or having wavelengths in at least one of an ultraviolet spectrum, a visible light spectrum, and an infrared spectrum.

The wavelength or wavelengths of the electromagnetic radiation may be chosen according to the photoluminescent properties of the taggant applied to the material web.

The first sensor and the second sensor may be configured to operate using electromagnetic radiation in the same spectrum. The first sensor and the second sensor may be configured to operate using electromagnetic radiation of substantially the same wavelength.

The first sensor and the second sensor may be configured to operate using electromagnetic radiation in different spectra. The first sensor and the second sensor may be configured to operate using electromagnetic radiation of different wavelengths.

The selection of appropriate electromagnetic radiation wavelengths will depend on the photochemical properties of the applied taggant.

The first sensor may be configured to determine the predetermined continuity of application quality condition without requiring a photoluminescent response from the taggant. For example, the first sensor may determine the continuity of application quality condition by determining an intensity or coloration or electromagnetic radiation reflected from the material web, with variations in the intensity or coloration indicating a variation in continuity of application quality condition. The second sensor, however, is preferably configured to detect a particular photoluminescent response elicited from the taggant after illumination with electromagnetic radiation of a specific wavelength or wavelengths, and this may be a different process to that used by the first sensor to determine that the taggant has been applied to meet the predetermined continuity of application quality condition.

In other examples, both the first sensor and the second sensor may be configured to elicit a photoluminescent response from the taggant by illuminating the taggant with electromagnetic radiation of a specific wavelength or wavelengths, and to detect the photoluminescent response. In these examples, the first sensor may be configured to confirm only that a photoluminescent response is elicited, while the second sensor may be configured to analyse particular properties of the photoluminescent response in more detail, for example by analysing a rate of decay of the photoluminescent response after illumination with electromagnetic radiation of a specific wavelength or wavelengths has temporarily ceased.

The first sensor and the second sensor may be configured to operate using electromagnetic radiation having a wavelength or wavelengths in a range of 600 nanometres (nm) to 1200nm.

The first sensor and the second sensor may be configured to operate using electromagnetic radiation having a wavelength or wavelengths in a range of 800nm to 1000nm.

Electromagnetic radiation at these wavelengths is well-suited for eliciting a good response from taggants typically used in the tobacco product and aerosol-generating system industry.

The taggant may be a photoluminescent taggant. Photoluminescence is light emission from any form of matter after the absorption of photons, and is initiated by photoexcitation. Following excitation, various relaxation processes typically occur in which other photons are re-radiated. Time periods between absorption and emission may vary, but are typically of the order of milliseconds in molecular systems.

The first sensor may be configured to emit a beam of electromagnetic radiation towards the taggant on the material web, and to receive electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the first sensor.

The second sensor may be configured to emit a beam of electromagnetic radiation towards the taggant on the cut portion of the material web, and to receive electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the second sensor.

The first sensor may be configured to emit a pulsed beam of electromagnetic radiation towards the taggant on the material web.

The second sensor may be configured to emit a pulsed beam of electromagnetic radiation towards the taggant on the cut portion of the material web.

The pulsed beam emitted by the first sensor may have a top-hat pulse profile.

The pulsed beam emitted by the second sensor may have a top-hat pulse profile, which may be the same as or different from the top-hat pulse profile of the first sensor.

The taggant may be a fluorescent taggant. Fluorescence is a form of photoluminescence in which the emitted electromagnetic radiation generally has a longer wavelength, and therefore a lower photon energy, than the absorbed electromagnetic radiation.

The taggant may be a phosphorescent taggant. Phosphorescence is a form of photoluminescence similar to fluorescence, but with a greater delay before electromagnetic radiation is emitted, often continuing for a longer period of time after the incident electromagnetic radiation has been removed. The delay is due to absorption of some of the photon energy by the taggant molecule.

The phosphorescent taggant may have a predetermined emission half-life. The emission half-life is the time taken for the emitted electromagnetic radiation intensity to fall by 50% from a maximum value after the incident electromagnetic radiation has been removed.

The first sensor may be configured to detect a phosphorescent response from the taggant but not to verify or determine the emission half-life of the phosphorescent taggant. The second sensor may be configured to verify or determine the emission half-life of the phosphorescent taggant. By using different detection mechanisms, the first and second sensors may be adapted to their different tasks so as to provide improved efficiency in the system. The first sensor may comprise an emitter to emit electromagnetic radiation towards the taggant. The second sensor may comprise an emitter to emit electromagnetic radiation towards the taggant.

The emitter of the first sensor may be configured to emit a pulsed beam of electromagnetic radiation towards the taggant on the material web.

The emitter of the second sensor may be configured to emit a pulsed beam of electromagnetic radiation towards the taggant on the cut portion of the material web.

The pulsed beam emitted by the emitter of the first sensor may have a top-hat pulse profile.

The pulsed beam emitted by the emitter of the second sensor may have a top-hat pulse profile, which may be the same as or different from the top-hat pulse profile of the first sensor.

The emitter in each of the first and second sensors may comprise a light emitting diode or a laser. The first sensor may have an emitter in the form of a light emitting diode and the second sensor may have an emitter in the form of a laser. The first sensor may have an emitter in the form of a laser and the second sensor may have an emitter in the form of a light emitting diode.

The first sensor may comprise a receiver to receive electromagnetic radiation emitted by the taggant. The second sensor may comprise a receiver to receive electromagnetic radiation emitted by the taggant. The receiver of the first sensor may comprise a photoreceiver, optionally a photodiode or a phototransistor. The receiver of the second sensor may comprise a photoreceiver, optionally a photodiode or a phototransistor.

According to another aspect of the present invention, there is provided a method of checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the method comprising: providing at least one first sensor; operating the at least one first sensor to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; providing at least one second sensor located downstream of the at least one first sensor on the manufacturing line; and operating the at least one second sensor to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

As used herein, the term “aerosol-generating article” refers to an article comprising an aerosol-forming substrate that, when heated in an aerosol-generating device, releases volatile compounds that can form an aerosol. An aerosol-generating article is separate from and configured for combination with the aerosol-generating device for heating the aerosolgenerating article.

As used herein, the term “amount” is used to describe a quantity of a material, component or object. An amount may be used to describe a number, a mass, extent or size in a quantitative manner.

As used herein, the term “apply” is used to describe a process of supplying or dispensing a material to another material, for example, on a material or within a material.

As used herein, the term “component” is used to describe an element of a larger whole. For example, component is used to describe a part of an aerosol-generating article. Component may also refer to more than one part of an aerosol-generating article.

As used herein, the term “concentration” is used to describe an amount of a substance per unit area, or volume. For example, the concentration is used to quantify an amount or density of a substance within a component.

As used herein, the term “detect” is used to describe a process of identifying the presence of a substance.

As used herein, the term “emission half-life” is used to refer to the time taken for an intensity of radiation emission by a photoluminescent material to decay by half after the photoluminescent material has been irradiated by a source of electromagnetic radiation and after the source of electromagnetic radiation has been removed or switched off.

As used herein, the term “emitter” is used to describe a device that emits a signal.

As used herein, the term “manufacturing line” refers to an arrangement in a factory by way of which articles are assembled from separate components in a generally linear sequence of mechanical operations. A manufacturing line may be implemented by a single apparatus, but is more usually implemented by several apparatuses arranged in sequence. In the context of a manufacturing line, the term “downstream” refers to locations through which the components or partially-assembled article pass subsequent to passing a given point, and the term “upstream” refers to locations through which the components or partially-assembled article pass prior to passing a given point.

As used herein, the term “material web” refers to a web of thin, flexible material, for example paper, that may be dispensed from a bobbin.

As used herein, the term “predetermined” is used to describe a parameter that is established in advance.

As used herein, the term “predetermined continuity of application quality condition” refers to a measure of a continuity of a band of taggant applied along a surface of a material web. The continuity of application quality condition is not met when a break or interruption is detected in the band of taggant applied along the surface of the material web. Optionally, the continuity of application quality condition is not met when a break or interruption greater than 1 millimetre is detected in the band of taggant applied along the surface of the material web Optionally, the continuity of application quality condition may not be met when a width of the band of taggant applied along the surface of the material web is detected to be smaller than a predetermined value. Optionally, the continuity of application quality condition may not be met when a width of the band of taggant applied along the surface of the material web is detected to be smaller than a predetermined value. Variations of the width of the band of applied taggant may be indicative of application nozzle blockage or depletion of a supply of taggant.

As used herein, the term “rod” is used to describe a component, segment or element, having a generally cylindrical cross-section, for use in an aerosol-generating article. The aerosol-generating article may comprise a number of different rods, for example, a filter rod. The cylindrical cross-section may be a circular cross-section or an oval cross-section, for example.

As used herein, the term “sensor” is used to describe a device which is used to measure a physical property of an environment. For example, the sensor may be a device that is used in the manufacturing process for measuring a physical property, such as a photoluminescent property, of a component for an aerosol-generating article.

As used herein, the term “profile of the taggant” is used to refer to a characteristic response of a taggant applied to a material web when irradiated with electromagnetic radiation of an appropriate wavelength or wavelengths. The response may, for example, be a photoluminescent response or a spectroscopic response. Different taggants may have different profiles, thus allowing taggants to be used to identify and distinguish between articles to which different taggants have been applied.

As used herein, the term “taggant” refers to a substance, for example a photoluminescent chemical compound, applied to a material web, the presence of which may be detected by a suitable detector to enable identification of aerosol-generating articles incorporating portions of the material web. The taggant may be sprayed or painted onto the material web in liquid form before subsequently drying. The taggant may include an appropriate solvent to facilitate rapid drying.

As used herein, the term “verify” is used to refer to a process in which a measured parameter is compared against a desired value or values of that parameter. The parameter is considered to be verified if the measured value is within a predetermined threshold range that includes the desired value of values,

The invention is defined in the claims. However, 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.

Example Ex1 : A system for checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the system comprising: at least one first sensor configured to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; and at least one second sensor located downstream of the at least one first sensor on the manufacturing line, the at least one second sensor configured to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

Example Ex2. The system according to Example Ex1 , wherein the material web is tipping paper.

Example Ex3. The system according to Example Ex1 or Ex2, wherein the material web is a band of material having a length that is at least 1000 times greater than a width of the band of material.

Example Ex4. The system according to Example Ex3, wherein the taggant is applied to the material web in the form of at least one substantially continuous band along the length of the material web.

Example Ex5. The system according to Example Ex3, wherein the taggant is applied to the material web in the form of at least two substantially continuous bands along the length of the material web.

Example Ex6. The system according to Example Ex4 or Ex5, wherein the first sensor is configured to indicate a fault condition if the first sensor detects an interruption in the at least one substantially continuous band or in at least one of the at least two substantially continuous bands.

Example Ex7. The system according to any one of Examples Ex4 to Ex6, wherein the first sensor is configured to indicate a fault condition if the first sensor detects a variation outside a predetermined range in the amount of taggant per unit length applied along the at least one substantially continuous band or in the amount of taggant per unit length applied along at least one of the at least two substantially continuous bands.

Example Ex8. The system according to any preceding Example, wherein the cut portions of the material web are configured as circumferential wrappers in rod-shaped articles.

Example Ex9. The system according to Example Ex8, wherein the taggant is present on exterior surfaces of the circumferential wrappers. Example Ex10. The system according to Example Ex8 or Ex9, wherein the taggant is present on interior surfaces of the circumferential wrappers.

Example Ex11. The system according to any one of Examples Ex8 to Ex10, wherein the second sensor is configured to inspect each circumferential wrapper at only one rotational orientation of the rod-shaped article with respect to a longitudinal axis of the rod-shaped article.

Example Ex12. The system according to any preceding Example, wherein the first sensor or the second sensor or the first sensor and the second sensor are configured to operate using electromagnetic waves having a wavelength or having wavelengths in at least one of an ultraviolet spectrum, a visible light spectrum, and an infra-red spectrum

Example Ex13. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation in the same spectrum.

Example Ex14. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation of substantially the same wavelength.

Example Ex15. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation in different spectra.

Example Ex16. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation of different wavelengths.

Example Ex17. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation having a wavelength or wavelengths in a range of 600nm to 1200nm.

Example Ex18. The system according to Example Ex12, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation having a wavelength or wavelengths in a range of 800nm to 1000nm.

Example Ex19. The system according to any preceding Example, wherein the taggant is a photoluminescent taggant.

Example Ex20. The system according to Example Ex19, wherein the first sensor is configured to emit a beam of electromagnetic radiation towards the taggant on the material web, and to receive electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the first sensor.

Example Ex21. The system according to Example Ex19 or Ex20, wherein the second sensor is configured to emit a beam of electromagnetic radiation towards the taggant on the cut portion of the material web, and to receive electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the second sensor.

Example Ex22. The system according to any one of Examples Ex19 to Ex21 , wherein the taggant is a fluorescent taggant.

Example Ex23. The system according to any one of Examples Ex19 to 21 , wherein the taggant is a phosphorescent taggant.

Example Ex24. The system according to Example Ex23, wherein the phosphorescent taggant has a predetermined emission half-life.

Example Ex25. The system according to Example Ex24, wherein the first sensor is configured to detect a phosphorescent response from the taggant but not to verify or determine the emission half-life of the phosphorescent taggant.

Example Ex26. The system according to Example Ex25, wherein the second sensor is configured to verify or determine the emission half-life of the phosphorescent taggant.

Example Ex27. The system according to any preceding Example, wherein the first sensor comprises an emitter to emit electromagnetic radiation towards the taggant.

Example Ex28. The system according to any preceding Example, wherein the second sensor comprises an emitter to emit electromagnetic radiation towards the taggant.

Example Ex29. The system according to Example Ex27 or Ex28, wherein the emitter comprises a light emitting diode.

Example Ex30. The system according to any one of Examples Ex27 to Ex29, wherein the emitter comprises a laser.

Example Ex31 . The system according to any preceding Example, wherein the first sensor comprises a receiver to receive electromagnetic radiation emitted by the taggant.

Example Ex32. The system according to any preceding Example, wherein the second sensor comprises a receiver to receive electromagnetic radiation emitted by the taggant.

Example Ex33. The system according to Example Ex29 or Ex30, wherein the receiver comprises a photoreceiver.

Example Ex 34. The system according to Example Ex33, wherein the photoreceiver comprises a photodiode.

Example Ex35. The system according to Example Ex33, wherein the photoreceiver comprises a phototransistor.

Example Ex36. A method of checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the method comprising: providing at least one first sensor; operating the at least one first sensor to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; providing at least one second sensor located downstream of the at least one first sensor on the manufacturing line; and operating the at least one second sensor to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

Example Ex37. The method according to Example Ex36, wherein the material web is tipping paper.

Example Ex38. The method according to Example Ex36 or Ex37, wherein the material web is a band of material having a length that is at least 1000 times greater than a width of the band of material.

Example Ex39. The method according to Example Ex38, wherein the taggant is applied to the material web in the form of at least one substantially continuous band along the length of the material web.

Example Ex40. The method according to Example Ex38, wherein the taggant is applied to the material web in the form of at least two substantially continuous bands along the length of the material web.

Example Ex41. The method according to Example Ex39 or Ex40, wherein the first sensor indicates a fault condition if the first sensor detects an interruption in the at least one substantially continuous band or in at least one of the at least two substantially continuous bands.

Example Ex42. The method according to any one of Examples Ex39 to Ex41 , wherein the first sensor indicates a fault condition if the first sensor detects a variation outside a predetermined range in the amount of taggant per unit length applied along the at least one substantially continuous band or in the amount of taggant per unit length applied along at least one of the at least two substantially continuous bands.

Example Ex43. The method according to any one of Examples Ex36 to Ex42, wherein the cut portions of the material web are wrapped around rod-shaped articles to form circumferential wrappers.

Example Ex44. The method according to Example Ex43, wherein the taggant is present on exterior surfaces of the circumferential wrappers.

Example Ex45. The method according to Example Ex43 or Ex44, wherein the taggant is present on interior surfaces of the circumferential wrappers. Example Ex46. The method according to any one of Examples Ex43 to Ex45, wherein the second sensor inspects each circumferential wrapper at only one rotational orientation of the rod-shaped article with respect to a longitudinal axis of the rod-shaped article.

Example Ex47. The method according to any one of Examples Ex36 to Ex46, wherein the first sensor or the second sensor or the first sensor and the second sensor operate using electromagnetic waves having a wavelength or having wavelengths in at least one of an ultraviolet spectrum, a visible light spectrum, and an infra-red spectrum

Example Ex48. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation in the same spectrum.

Example Ex49. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation of substantially the same wavelength.

Example Ex50. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation in different spectra.

Example Ex51. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation of different wavelengths.

Example Ex52. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation having a wavelength or wavelengths in a range of 600nm to 1200nm.

Example Ex53. The method according to Example Ex47, wherein the first sensor and the second sensor operate using electromagnetic radiation having a wavelength or wavelengths in a range of 800nm to 1000nm.

Example Ex54. The method according to any one of Examples Ex36 to Ex53, wherein the taggant is a photoluminescent taggant.

Example Ex55. The method according to Example Ex54, wherein the first sensor emits a beam of electromagnetic radiation towards the taggant on the material web, and receives electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the first sensor.

Example Ex56. The method according to Example Ex54 or Ex55, wherein the second sensor emits a beam of electromagnetic radiation towards the taggant on the cut portion of the material web, and receives electromagnetic radiation emitted by the taggant in response to the beam of electromagnetic radiation emitted by the second sensor.

Example Ex57. The method according to any one of Examples Ex54 to Ex56, wherein the taggant is a fluorescent taggant.

Example Ex58. The method according to any one of Example Ex54 to Ex56, wherein the taggant is a phosphorescent taggant. Example Ex59. The method according to Example Ex58, wherein the phosphorescent taggant has a predetermined emission half-life.

Example Ex60. The method according to Example Ex59, wherein the first sensor detects a phosphorescent response from the taggant but does not verify or determine the emission half-life of the phosphorescent taggant.

Example Ex61. The method according to Example Ex60, wherein the second sensor verifies or determines the emission half-life of the phosphorescent taggant.

Example Ex62. The method according to any one of Examples Ex36 to Ex61 , wherein the first sensor comprises an emitter to emit electromagnetic radiation towards the taggant.

Example Ex63. The method according to any one of Examples Ex36 to Ex62, wherein the second sensor comprises an emitter to emit electromagnetic radiation towards the taggant.

Example Ex64. The method according to Example Ex62 or Ex63, wherein the emitter comprises a light emitting diode.

Example Ex65. The method according to any one of Examples Ex62 to Ex64, wherein the emitter comprises a laser.

Example Ex66. The method according to any one of Examples Ex36 to Ex65, wherein the first sensor comprises a receiver to receive electromagnetic radiation emitted by the taggant.

Example Ex67. The method according to any one of Examples Ex36 to Ex66, wherein the second sensor comprises a receiver to receive electromagnetic radiation emitted by the taggant.

Example Ex68. The method according to Example Ex66 or Ex67, wherein the receiver comprises a photoreceiver.

Example Ex69. The method according to Example Ex68, wherein the photoreceiver comprises a photodiode.

Example Ex70. The method according to Example Ex68, wherein the photoreceiver comprises a phototransistor.

Examples will now be further described with reference to the figures in which:

Figure 1 shows an aerosol-generating article manufacturing line in schematic form, comprising a rod-making section and a combiner section;

Figure 2 shows the combiner section of Figure 1 in cross-sectional view;

Figure 3 shows an arrangement where a band of material web runs past a pair of first sensors;

Figure 4 shows an arrangement where rod-shaped aerosol-generating articles on the surface of a conveyor drum pass under a second sensor; Figure 5 shows an arrangement where a band of material web runs past three first sensors;

Figure 6 shows an arrangement where a band of material web runs past a pair of first sensor front ends electrically connected to a controller; and

Figure 7 shows an arrangement where double length rods on the surface of a conveyor drum pass under two second sensors.

Figure 1 shows a manufacturing line 100 comprising a rod-making section 200 and a combiner section 300. In the rod-making section 100, rod-shaped components A, B and C are placed onto a continuous band of wrapper material supported by a garniture tape. The garniture tape, wrapper material and rod-shaped components then pass longitudinally along direction T 1 through a shaping assembly that curves the garniture tape and the supported band of wrapper material around the segments A, B and C so as to form a continuous rod CR. The continuous rod CR is then cut into individual wrapped rods 1 by a cutter 210.

Component A may be a filter rod, component B may be a hollow acetate tube, and component C may be a tobacco rod, although this is just a non-limiting example.

After cutting, the individual wrapped rods 1 are passed on to the combiner section 300, shown in more detail in Figure 2. The individual wrapped rods 1 travel through the combiner section 300 in an overall general direction T2. In the illustrated example, the individual wrapped rods 1 are disposed substantially transverse to the direction T2.

The combiner section 300 is configured to take individual wrapped rods 1 that have been cut from the continuous rod CR and to arrange the individual wrapped rods 1 pair-wise, each pair of individual wrapped rods 1 being disposed along a straight line generally transverse to the direction of travel T2. Each pair of individual wrapped rods 1 is linearly arranged so that a segment A of one individual wrapped rod 1 is closest to a segment A of its corresponding individual wrapped rod 1 in the pair, with a space between respective segments A of the pair.

A further rod-shaped segment D is then placed in the space between the individual wrapped rods 1 of each pair, and a tipping paper (not shown in Figure 1) is wrapped around the rod-shaped segment D and the facing ends of each pair of individual wrapped rods 1 so as to form a double length rod (not shown in Figure 1). The rod-shaped segment D may be a mouthpiece.

The double rods are then cut in half through the tipping paper and the rod-shaped segment D so as to form individual aerosol-generating articles 310.

Figure 2 shows a cross-section through the combiner section 300 of Figure 1. A placement device 320 takes individual wrapped rods 1 from the rod-making section 200 and arranges the individual wrapped rods 1 pairwise in an end-to-end configuration in grooves on a surface of a first conveyor drum 330. Generally, the individual wrapped rods 1 are temporarily held in the groove of the conveyor drum 330 by pneumatic suction.

The pairs of individual wrapped rods 1 are passed along direction T2 by way of a sequence of rotating conveyor drums 331 , 332, 333 and 334. During passage along direction T2, the individual wrapped rods 1 are positioned precisely relative to each other so as to provide a gap between segment A ends of each pair of individual wrapped rods 1 . Operational details of conveyor drums in combiner machines are known to those skilled in the art, and need not be described in detail in the present disclosure.

Rod-shaped segments D, for example mouthpieces, are placed in the spaces between segment A ends of respective pairs of individual wrapped rods 1 on conveyor drum 334 by way of conveyor drums 340, 341 and 342.

The pairs of individual wrapped rods 1 with their centrally-disposed rod-shaped segments D are then passed further along direction T2 by way of conveyor drums 335 and 336.

At conveyor drum 335, each pair of individual wrapped rods 1 with its centrally-disposed rod-shaped segment D is provided with a tipping paper that is wrapped around the rod-shaped segment D and the facing ends of each pair of individual wrapped rods 1 so as to form double length rods 9, which are then passed on to conveyor drum 336 and then on to conveyor drum 6. The double length rods 9 are subsequently cut in half through the tipping paper and the rod-shaped segment D so as to form individual aerosol-generating articles 310.

Instead of forming double length rods 9 from end-to-end arranged individual wrapped rods 1 and centrally-disposed rod-shaped segments D, it is also possible for a combiner 300 to be configured to transport individual wrapped rods 1 as a single, rather than a double, stream along direction T2. In this alternative, rod-shaped segments D are individually attached to segment A ends of each individual wrapped rod 1 by way of tipping paper, and no subsequent cutting step is required. However, combiners 300 that process double length rods

9 generally have a greater throughput than combiners that only process single rods.

The general operation of the rod-making section 200 and the combiner section 300 is known to those skilled in the art, and will not be described in further detail in the present disclosure.

Referring to Figures 1 and 2, embodiments of the present disclosure particularly relate to a part of the manufacturing line 100 where a material web 2, for example tipping paper, is dispensed from a bobbin 4 at a relatively high speed. The material web 2 passes a first sensor

10 at the relatively high speed, and is then cut into tipping paper portions at drum 339 by a cutter 5. The cut tipping paper portions of the material web 2 are then used to join the individual wrapped rods 1 to their respective rod-shaped segments D (either to form individual rods or double length rods 9) at the interface between drums 335 and 339. The individual wrapped rods 1 and the rod-shaped segments D are joined by wrapping the cut tipping paper portions around the interface between the individual wrapped rods 1 and the rod-shaped segments D with an adhesive or the like. The rods are then transferred via conveyor drum 336 to conveyor drum 6, where they pass a second sensor 20 at a relatively low speed. In this context, the speeds of travel past the respective first sensor 10 and second sensor 20 are defined relative to each other, i.e. the speed of travel of the material web 2 past the first sensor

10 is much higher than the speed of travel of the rods past the second sensor 20.

Figure 3 shows an embodiment where a band of material web 2 to which a taggant has been applied in two substantially continuous bands 3, 33 along the length of the material web 2. The two continuous bands 3, 33 of taggant have been applied to an upper surface of the band of material web 2 substantially parallel to each other, and also substantially parallel to the longitudinal direction of the band of material web 2. In the embodiment of Figure 3, two first sensors 10, 11 are provided, with one first sensor 10 configured to inspect one of the continuous bands 3 of taggant, and the other first sensor 11 configured to inspect the other of the continuous bands 33 of taggant. The first sensor 10 comprises an emitter configured to emit a pulsed beam of electromagnetic radiation 350 towards the band 3 of taggant on the material web 2, and a receiver configured to receive electromagnetic radiation 360 emitted by the band 3 of taggant on the material web 2 in response to the pulsed beam of electromagnetic radiation 350. When the pulsed beam of electromagnetic radiation 350 is “on”, photons are absorbed by the band 3 of taggant as a result of electron transitions in the taggant. When the pulsed beam of electromagnetic radiation 350 is “off”, the electrons in the taggant will return to a lower energy state, resulting in emission of the electromagnetic radiation 360 that is detected by the first sensor 10. Similarly, the other first sensor 11 comprises an emitter configured to emit a beam of electromagnetic radiation 351 towards the other band 33 of taggant on the material web 2, and a receiver configured to receive electromagnetic radiation 361 emitted by the other band 33 of taggant on the material web 2. The receivers of the first sensors 10, 11 may continue to be operational both when the emitters of the first sensors 10,

11 are on and when the emitters of the first sensors 10, 11 are off. While the emitters of the first sensors 10, 11 are on, and for a short period thereafter, the receivers of the first sensors 10, 11 may indicate a maximum emission signal, after which a received and detected intensity of received electromagnetic radiation 360, 361 will start to decrease from the maximum level, indicating the presence of sufficient taggant in the band 3 of taggant. By appropriate selection of the pulse width and frequency of the pulsed beam of electromagnetic radiation 350, 351 in combination with a speed of travel of the band of material web 2 past the first sensors 10, 11 , it is possible to determine whether or not the taggant has been applied to meet a predetermined continuity of application quality condition.

The first sensors 10, 11 are preferably not configured to detect a predetermined profile of the taggant. Alternatively or in addition, the first sensors 10, 11 are preferably not configured to detect a predetermined concentration of the taggant. Detecting a predetermined profile of a taggant is generally a slower process than detecting a taggant continuity of application quality condition, since detecting the predetermined profile usually requires analysing a rate of decay of intensity of electromagnetic radiation 360, 361 emitted by the taggant and performing appropriate calculations. This analysis typically takes a time of the order of milliseconds. Similar considerations apply to detecting a predetermined concentration of the taggant. Accordingly, band of material web 2 can be run past the first sensors 10, 11 at a higher speed than would be possible if it was necessary for the first sensors 10, 11 to detect a predetermined profile or concentration of the taggant. This means that the speed of travel of the band of material web 2 past the first sensors 10, 11 is not unduly limited, thus improving speed of manufacture of the aerosol-generating articles.

If the first sensor or sensors 10, 11 detects an interruption or discontinuity in the band or bands of taggant 3, 33 applied to the band of material web 2, then a signal may be given to reject an aerosol-generating article 310 comprising a tipping paper 400 bearing the interrupted or discontinuous band or bands of taggant 3, 33. In extreme situations, such as the first sensor or sensors 10, 11 detecting that no taggant 3 is present at all on an extended length of material web 2, the manufacturing line 100 may be temporarily stopped so as to allow a replacement bobbin 4 of material web 2 to be installed.

Figure 4 shows in detail a plurality of rod-shaped aerosol-generating articles 310 on the conveyor drum 6 of Figure 2. Each aerosol-generating article 310 comprises an individual wrapped rod 1 joined to a rod-shaped segment D by a cut portion of the band of material web 2 (not shown in Figure 4) configured as a tipping paper 400. In the illustrated embodiment, the band of material web 2 has only a single continuous band 3 of taggant. The aerosolgenerating articles 310 are held in grooves 410 on the surface of the conveyor drum 6, for example by way of pneumatic suction.

A second sensor 20 is mounted adjacent to the conveyor drum 6. The second sensor 20 comprises an emitter configured to emit a beam of electromagnetic radiation 430 towards the band 3 of taggant on the tipping paper 400, and a receiver configured to receive electromagnetic radiation 440 emitted by the band 3 of taggant on the tipping paper 400.

The conveyor drum 6 is configured to rotate about an axis 420. Preferably, the conveyor drum 6 is configured to rotate continuously. The speed of travel of the rod-shaped aerosolgenerating articles 310 past the second sensor is less than the speed of travel of the band of material web 2 past the first sensor or sensors 10, 11. This means that there is sufficient time for the incident beam of electromagnetic radiation 430 to elicit a photoluminescent response from the taggant 3 on the tipping paper 400 and for the rate of decay of intensity of emitted electromagnetic radiation from the taggant 3 to be analysed. For example, the incident beam of electromagnetic radiation 430 may be directed at the taggant 3 on the tipping paper 400 for a first predetermined time, sufficient to excite electrons in the taggant 3 to a higher energy state, and the emitter in the second sensor may then be switched off. The electrons in the taggant 3 will then return to a lower energy state, emitting photons as the electromagnetic radiation 440 that is detected by the receiver in the second sensor 20. An emission half-life of the taggant 3 can be determined by measuring an intensity of the electromagnetic radiation 440 emitted by the taggant 3 and determining a time taken for the intensity to fall by 50% from a peak value at a time when the emitter in the second sensor 20 is switched off. The emission half-life of the taggant 3 can be correlated with a predetermined profile of the taggant 3. Alternatively or in addition, the emission half-life of the taggant can be correlated with a predetermined concentration of the taggant 3.

The conveyor drum 6 continues to rotate so that the next aerosol-generating article 310 passes under the second sensor 20, and the emitter of the second sensor 20 is switched on again to repeat the process described above.

Importantly, because the first sensor or sensors 10, 11 have already checked the predetermined continuity of application quality condition, there is no need to the aerosolgenerating articles 310 to be rotated within the grooves 410 of the conveyor drum 6 when being inspected by the second sensor 20. It will already have been established by the first sensor or sensors 10, 11 that the band of taggant 3 has been applied evenly all the way around the tipping paper 400 on the aerosol-generating article 310. Accordingly, the second sensor 20 need only inspect the taggant 3 on the aerosol-generating articles 310 at a single rotational orientation of the aerosol-generating article 310 with respect to a longitudinal axis of the aerosol-generating article 310. This improves the speed of manufacture of the aerosolgenerating articles, since the conveyor drum 6 can rotate more quickly than would be the case if it were necessary to inspect the taggant 3 on the tipping paper 400 in multiple rotational orientations of the aerosol-generating article.

If the second sensor 20 determines that the taggant 3 does not elicit the correct response to the incident beam of electromagnetic radiation 430, for example because the concentration of taggant 3 is too low, or because the taggant 3 is contaminated, then a signal may be given to reject the aerosol-generating article 310 (or double length rod 9) comprising the tipping paper 400 with the defective taggant 3. Although the illustrated embodiment shows individual aerosol-generating articles 310, it will be understood that double length rods 9 could be conveyed by the drum, and two second sensors 20 could be provided so as to inspect the taggant on each half of the respective double length rods 9.

The taggant 3 may be applied to the band of material web 2 on the manufacturing line 100, for example by way of a spray nozzle. Alternatively, the band of material web 2 may have the taggant 3 applied before feeding into the manufacturing line 100. The band of material web 2 may have taggant 3 applied during manufacture, or prior to being wound onto the bobbin 4.

Preferably, the taggant 3 is applied to a surface of the band of material web 2 that will form an exterior surface of a tipping paper 400 on an aerosol-generating article 310. This means that electromagnetic radiation does not have to penetrate the tipping paper 400 before eliciting a photoluminescent response. This is also of benefit when the aerosol-generating article 310 is inserted into an aerosol-generating device (not shown) where electromagnetic radiation is used to identify a predetermined profile of the taggant 3 so as to identify a type or provenance of the aerosol-generating article 310.

However, there may be implementations where the taggant 3 is applied to a surface of the band of material web 2 that will form an interior surface of a tipping paper 400 on an aerosol-generating article 310. Although it is necessary for electromagnetic radiation to penetrate the tipping paper 400 in these implementations, locating the taggant 3 on the interior surface of the tipping paper 400 may help to prevent the taggant 3 from being inadvertently removed from the tipping paper 400 by rough handling or exposure to moisture.

Advantageously, the first sensor or sensors 10, 11 are positioned at a point in the production line 100 immediately before the band of material web 2 is cut into portions. This ensures that the continuity of application quality condition is determined after the band of material web 2 has been dispensed from the bobbin 4 and passed over a number of tensioning rollers, since these handling steps might themselves damage the band of applied taggant 3 and introduce unwanted discontinuities. By performing the continuity of application quality condition check immediately before cutting the band of material web 2 into portions, a more reliable indication of continuity of application quality around the tipping paper 400 on a finished aerosol-generating article is obtained.

Figure 5 shows an implementation where a band of material web 2 bearing a single band of taggant 3 passes under three first sensors 10, 12, 13 arranged in a line along a direction of travel of the band of material web 2. For bands of material web 2 having two bands of taggant 3, 33 (as shown in Figure 3), a corresponding plurality of first sensors 10, 12, 13 may be provided to check the continuity of application quality condition of the band of taggant 33 on the other edge of the band of material web 2. In the implementation of Figure 5, the plurality of first sensors 10, 12, 13, arranged in line, means that each first sensor 10, 12, 13 checks a different section of the band of taggant 3, 33, thus enabling the band of material web 2 to travel even faster past the first sensors 10, 12, 13 in comparison to an implementation where the continuity of taggant application is checked by a single first sensor 10, thereby increasing production speed.

Figure 6 shows a particular implementation of two first sensors 10, 11 in the form of front ends arranged side-by-side with the band of material web 2 passing below the two first sensors 10, 11. The band of material web 2 has two bands of taggant 3, 33. The two first sensor 10, 11 front ends are electrically connected to a controller 600. The controller 600 drives the first sensor 10, 11 front ends and receives signals from the first sensor 10, 11 front ends. Each first sensor 10, 11 front end comprises an emitter in the form of a laser diode or LED to emit electromagnetic radiation, and a receiver in the form of a photodiode or phototransistor to receive electromagnetic radiation. Each first sensor 10, 11 front end may be narrower than 36mm in order to accommodate the narrowest commercial bands of material web 2 used for tipping paper. Different widths of bands of material web 2 may be accommodated by adjusting a spacing between the first sensor 10, 11 front ends. The control unit 600 may include, for each of the first sensor 10, 11 front ends, a programmable logic controller (PLC) connector 610 and a diagnostic connector 620.

Figure 7 shows a particular implementation of two second sensors 20, 21 in the form of front ends arranged side-by-side above a conveyor drum 6 conveying double length rods 9 each formed from two individual wrapped rods 1 arranged end-to-end with an intervening rodshaped segment D and joined by a tipping paper 400 with two bands of taggant 3, 33. The two second sensor 20, 21 front ends are electrically connected to a controller (not shown). The controller drives the second sensor 20, 21 front ends and receives signals from the second sensor 20, 21 front ends. Each second sensor 20, 21 front end comprises an emitter in the form of a laser diode or LED to emit electromagnetic radiation, and a receiver in the form of a photodiode or phototransistor to receive electromagnetic radiation emitted by the taggant 3, 33 in response to the electromagnetic radiation emitted by the laser diode or LED of the respective second sensor 20, 21 front end. The second sensor 20, 21 front ends may operate on a different measuring principle to the first sensor 10, 11 front ends. Instead of just checking for a fall-off of electromagnetic radiation from a maximum level, the receivers of the second sensor 20, 21 front ends are configured to determine a rate of decay of intensity of the photoluminescent response from the taggant 3, 33. For example, an emission half-life of a phosphorescent taggant 3, 33 can be determined by measuring a time taken for an intensity of electromagnetic radiation emitted as a phosphorescent response by the taggant 3, 33 to reduce by 50% from a peak value when the emitters of the second sensor 20, 21 front ends is switched off.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. A system for checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the system comprising: at least one first sensor configured to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; and at least one second sensor located downstream of the at least one first sensor on the manufacturing line, the at least one second sensor configured to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

2. The system according to claim 1 , wherein the material web is tipping paper.

3. The system according to claim 1 or 2, wherein the taggant is applied to the material web in the form of at least one substantially continuous band along a length of the material web.

4. The system according to claim 3, wherein the first sensor is configured to indicate a fault condition if the first sensor detects an interruption in the at least one substantially continuous band.

5. The system according to claim 3 or 4, wherein the first sensor is configured to indicate a fault condition if the first sensor detects a variation outside a predetermined range in the amount of taggant per unit length applied along the at least one substantially continuous band or in the amount of taggant per unit length applied along at least one of the at least two substantially continuous bands.

6. The system according to any preceding claim, wherein the cut portions of the material web are configured as circumferential wrappers in rod-shaped articles, and wherein the taggant is present on exterior surfaces of the circumferential wrappers.

7. The system according to claim 6, wherein the second sensor is configured to inspect each circumferential wrapper at only one rotational orientation of the rod-shaped article with respect to a longitudinal axis of the rod-shaped article.

8. The system according to any preceding claim, wherein the first sensor or the second sensor or the first sensor and the second sensor are configured to operate using electromagnetic waves having a wavelength or having wavelengths in at least one of an ultraviolet spectrum, a visible light spectrum, and an infra-red spectrum

9. The system according to claim 8, wherein the first sensor and the second sensor are configured to operate using electromagnetic radiation of different wavelengths.

10. The system according to any preceding claim, wherein the taggant is a phosphorescent taggant having a predetermined emission half-life, and wherein the first sensor is configured to detect a phosphorescent response from the taggant but not to verify or determine the emission half-life of the phosphorescent taggant.

11. The system according to claim 10, wherein the second sensor is configured to verify or determine the emission half-life of the phosphorescent taggant.

12. A method of checking a presence and integrity of taggant applied to components of aerosol-generating articles during manufacture of the aerosol-generating articles on a manufacturing line, the method comprising: providing at least one first sensor; operating the at least one first sensor to detect a taggant applied to a surface of a material web and to determine that the taggant has been applied to meet a predetermined continuity of application quality condition; providing at least one second sensor located downstream of the at least one first sensor on the manufacturing line; and operating the at least one second sensor to inspect portions of the material web after the material web has been cut into portions and to confirm at least one of a predetermined profile of the taggant and a predetermined concentration of the taggant.

13. The method according to claim 12, wherein the first sensor indicates a fault condition if the first sensor detects a variation outside a predetermined range in the amount of taggant per unit length applied along the at least one substantially continuous band.

14. The method according to claim 12 or 13, wherein the taggant is a phosphorescent taggant having a predetermined emission half-life, and wherein the first sensor detects a phosphorescent response from the taggant but does not verify or determine the emission halflife of the phosphorescent taggant.

15. The method according to claim 14, wherein the second sensor verifies or determines the emission half-life of the phosphorescent taggant.