Perforation inspection apparatus and method

Abstract

An inspection device for inspecting radial perforations in a tubular component of an aerosol-generating article, the device comprising: a housing comprising an illumination device, the illumination device including a light guide that extends out of the housing; wherein the light guide is configured to be inserted into the tubular component along the longitudinal axis of the tubular component and is operable to transmit light from the illumination device to an inside of the tubular component.

Description

[0001] PERFORATION INSPECTION APPARATUS AND METHOD

[0002] The present disclosure relates to an apparatus and method for at-line inspection of radial perforations formed in rod-shaped aerosol-generating articles.

[0003] It is known that ventilation of tobacco articles is a key factor that can be manipulated to control the nicotine and condensate contents of tobacco smoke. During manufacturing, a tobacco article may be provided with a series of perforations to enhance ventilation and optimize aerosol formation. Often, these perforations form ventilated conduits extending from the outermost wrapping material to penetrate across a filter plug. These perforations have the primary function of generating zones with a desired permeability, allowing cool atmospheric air to enter the tobacco smoke stream, thus modulating the characteristics and intensity of the smoke inhaled by the consumer.

[0004] Such ventilation by way of radial perforations is also employed in heat-not-burn type aerosol-generating articles where an aerosol is generated by heating an aerosol-generating substrate, for example tobacco cast leaf, and the aerosol is then drawn through aerosol-cooling components or filter components as described above.

[0005] For example, in a multi-segment tobacco article 1 , as shown in Figure 1 , a series of radial perforations 2 extend circumferentially along a region corresponding to a fine hollow acetate tube (FHAT) filter segment 3. The perforations 2 may be formed using a laser apparatus, which emits a focused beam with an accurate penetration depth.

[0006] The perforations must be completed during the manufacture phase according to exact specifications so as to provide the desired ventilation. To verify that all equipment functions as intended and that the established perforating process meets an established quality criterion, conventional off-line measurements are employed, in which a collected sample is transferred to a testing laboratory. It is widely recognized that that the primary method to ascertain the accuracy of perforations and to confirm that the laser beam has effectively penetrated the FHAT segment 3 is through scanning the perforated region with either a tomograph or a computerized tomography, CT, scan.

[0007] Figure 2 shows a complete multi-segment tobacco article 1 with radial perforations 2. As depicted in Figure 3, a cross-sectional image from a CT scan displays radial conduits traversing the FHAT segment 3 filter. To confirm that all perforations are adequate, a CT scan should reveal a conduit 4 that runs completely through the surrounding wall of the tubular filter. An incomplete perforation 5 is evident in Figure 3, where the laser penetration depth is shallower than what is required.

[0008] The known procedure for validating the quality of the perforations requires that samples are sent to equipment located in a specialized laboratory for analysis. This procedure typically has a lead time of at least two weeks. Such a delay is disadvantageous as the production line continues to run uninterrupted while awaiting these results, which could potentially result in faulty articles advancing through the production process and ultimately reaching the end consumer.

[0009] According to a first aspect of the present invention, there is provided an inspection device for inspecting radial perforations in a tubular component of an aerosol-generating article, the device comprising: a housing comprising an illumination device, the illumination device including a light guide that extends out of the housing; wherein the light guide is configured to be inserted into the tubular component along the longitudinal axis of the tubular component and is operable to transmit light from the illumination device to an inside of the tubular component.

[0010] The light passes from the inside of the tubular component through the radial perforations, and a quality of the radial perforations can be checked by inspecting an image formed by the light in an image plane of a camera or microscope.

[0011] The device of this aspect of the present invention allows tubular components to be inspected at-line, with minimal delay, and can help to provide an early indication in the event that the radial perforations are being imperfectly formed in the manufacturing process without having to send sample tubular components to a remote laboratory for time-consuming CT scanning. This reduces the risk of a large number of imperfect tubular components being manufactured before a problem is identified. An imperfectly formed radial perforation may be a radial perforation that does not extend cleanly through an entire thickness of a wall of the tubular component. An imperfectly formed radial perforation may be a radial perforation that has a diameter that does not fall within predetermined tolerances. An imperfectly formed radial perforation may be a radial perforation that does not extend through a wrapper provided circumferentially around the tubular component.

[0012] The tubular component may be a hollow acetate tube (HAT) component. A hollow acetate tube component is a tubular component, usually open at both ends, made of cellulose acetate fibres with a plasticizer. HAT components may be provided with a circumferential paper wrapper during manufacture of the HAT component. Alternatively, HAT components may be manufactured without a circumferential wrapper, but subsequently provided with a circumferential paper wrapper when wrapped together with other cylindrical components to produce an aerosolgenerating article. The tubular component may be a fine hollow acetate tube (FHAT) component. FHAT components are similar to HAT components, but have a thinner circumferential wall and a correspondingly larger internal diameter.

[0013] The tubular component may be a cardboard or paperboard tubular component. This may be advantageous in terms of sustainability, since cardboard or paperboard, made of wood pulp fibres, is more biodegradable than cellulose acetate fibres. The tubular component may alternatively be made of other materials, for example polylactic acid (PLA) or other appropriate polymers.

[0014] The tubular component, as described above, is provided with radial perforations. The radial perforations allow for ingress of ambient air into an inner lumen of the tubular component when a consumer draws on a mouthpiece of an aerosol-generating article incorporating the tubular component. This may provide a ventilating effect so as to modify certain parameters of the aerosol passing along the inner lumen of the tubular component. For example, the air may cool the aerosol. For example, the air may reduce an intensity or concentration of the aerosol.

[0015] The tubular component may be held manually when inserting the light guide into the tubular component. For example, the tubular component may be held between a finger and thumb when inserting the light guide into the tubular component. The tubular component may be manually rotated about the longitudinal axis of the tubular component.

[0016] The device may further comprise a sample holder configured to hold the tubular component such that the tubular component is rotatable about a longitudinal axis of the tubular component. This may advantageously help to keep the tubular component steady during inspection. This may allow for more precise fine rotational control of the tubular component.

[0017] The sample holder of the inspection device may be connected to the housing by a bridge portion.

[0018] The bridge portion may connect a lower part of the sample holder to a lower part of the housing so as to define an inspection gap above the bridge portion between the sample holder and the housing.

[0019] In this way, the sample holder and the housing together form an integrated inspection device, with the sample holder configured to hold the tubular component at a correct position to allow the light guide to be inserted. Advantageously, the sample holder is configured such that the light guide can be inserted into an inner lumen of the tubular member. The light guide may extend out of the housing in a direction towards the sample holder. When the light guide is correctly inserted into the tubular component, light emitted by the light guide in a radial direction will be directed radially outward, with at least some of the light passing through at least some of the radial perforations to an outside of the tubular component.

[0020] The sample holder may comprise a tubular aperture configured to receive the tubular component. Preferably, the tubular aperture of the sample holder is configured to hold the tubular component so that the tubular component is rotatable about the longitudinal axis of the tubular component. The tubular aperture may be provided with a spring bushing configured rotatably to hold the tubular component. In this way, it is possible to rotate the tubular component around the light guide so as to enable inspection of the radial perforations around the entire circumference of the tubular component from a given line of sight. The tubular aperture may have a longitudinal axis that is substantially coincident with the longitudinal axis of the tubular component when the tubular component is received in the tubular aperture. The longitudinal axis of the tubular aperture may be substantially coincident with a longitudinal axis of the light guide. This may facilitate rotation of the tubular component around the longitudinal axis of the tubular component and around the light guide.

[0021] The light guide may be configured for insertion into at least a portion of the tubular component that is disposed within the inspection gap when the tubular component is held by the sample holder. This allows for easy inspection of light passing radially outwardly from the light guide and through the radial perforations in the tubular component by positioning a camera or microscope or other appropriate optical detector in a vicinity of the inspection gap. For example, a camera or microscope may be positioned above the inspection gap, or to one side of the inspection gap, and the tubular component rotated in the sample holder around the longitudinal axis of the tubular component so as to align different radial perforations, around the circumference of the tubular component, for inspection between the light guide and the camera or microscope.

[0022] The device may further comprise a rotation mechanism configured to rotate the tubular component about the longitudinal axis of the tubular component when the tubular component is rotatably held by the sample holder. The rotation mechanism may comprise a gearing mechanism. This may facilitate accurate fine rotational control when rotating the tubular component. It will be appreciated that accurate alignment of a radial perforation with respect to a light path from the light guide is important, and direct rotation of the tubular component, for example by way of an operator’s fingers, may not be sufficiently accurate. Accordingly, a rotation mechanism, for example a gearing mechanism, that provides a velocity ratio greater than one will allow improved fine rotational control.

[0023] The rotation mechanism may be a manually operated mechanism.

[0024] The rotation mechanism may comprise an electric motor. The electric motor may be a servomotor. The electric motor may be a stepper motor. The stepper motor may be configured to rotate the tubular component through a rotational angle corresponding to an angle subtended by two radial perforations, for example two circumferentially-adjacent radial perforations. The electric motor may be controlled by an actuator switch.

[0025] The illumination device may comprise an optical fibre cable and the light guide may comprise a radiating tip portion of the optical fibre cable. The radiating tip portion may have a longitudinal axis coincident with or parallel to the longitudinal axis of the tubular component. The radiating tip portion may be configured to emit light substantially radially from the longitudinal axis of the radiating tip portion.

[0026] The radiating tip portion of the optical fibre cable may extend from a substantially rigid termination portion of the optical fibre cable. The radiating tip portion may be substantially rigid. This may help to keep the radiating tip portion correctly aligned when inserted into the tubular component.

[0027] The optical fibre cable may have a connecting end portion at an end of the optical fibre cable remote from the radiating tip portion. The connecting end portion of the optical fibre cable may be configured for optical connection to a light source. The light source may be external to the housing of the inspection device. The light source may be internal to the housing of the inspection device.

[0028] A portion of the optical fibre cable between the radiating tip portion and the remote connecting end portion may be disposed within a substantially cylindrical housing. The substantially cylindrical housing is preferably substantially impermeable to light. This may promote total internal reflection in the optical fibre cable. The cylindrical housing may comprise two semi-cylindrical components that are attached to each other around the optical fibre cable.

[0029] The cylindrical housing may form part of a body of the illumination device. The cylindrical housing may be contained in or mounted on the housing of the illumination device. The cylindrical housing may also help to ensure that the light guide is correctly positioned, by holding less rigid parts of the optical fibre cable in a correctly aligned longitudinal configuration.

[0030] In some embodiments, the illumination device may include a light source. In other embodiments, the light source may be external to the illumination device and connected thereto by an optical fibre cable. The light source may be a light emitting diode. The light source may be a laser.

[0031] The light guide may be configured to emit light from the longitudinal axis in all radial directions.

[0032] The light guide may be configured to emit light from the longitudinal axis in only a predetermined sector of radial directions. An angle subtended by the sector of radial directions may be less than 90 degrees, optionally less than 45 degrees, optionally less than 25 degrees, optionally less than 10 degrees. In this way, it may be possible to concentrate the emitted light in a direction generally towards an optical detector, for example a camera or a microscope.

[0033] The device may be provided in combination with a microscope or camera configured to detect light passing through the radial perforations in the tubular component from the light guide.

[0034] The microscope or camera may be disposed over or adjacent to the inspection gap.

[0035] By detecting light passing through the radial perforations and examining characteristics of a pattern or image formed by the light on a detection plane of the camera or microscope, it is possible to determine whether or not a given radial perforation meets desired quality criteria. For example, when a given radial perforation correctly extends through an entire wall thickness of the tubular component, light passing through the radial perforation from the light guide will form an image on the detection plane with a well-defined peripheral edge. Conversely, when a given radial perforation does not correctly extend through the entire wall thickness of the tubular component, light passing through the radial perforation from the light guide will form an image on the detection plane with a poorly-defined or blurred peripheral edge. This is because the light will tend to scatter more in the event of obstructions or constrictions in the radial perforation, giving rise to the poorly-defined or blurred peripheral edge in the image plane. Obstructions or constrictions in the radial perforations both in the body of the tubular component and in any wrapper that may be provided around the tubular component may thus be detected.

[0036] According to a second aspect of the present invention, there is provided a method of inspecting radial perforations in a tubular component of an aerosol-generating article, the method comprising the steps of: i) inserting a light guide into the tubular component along a longitudinal axis of the tubular component; ii) directing light from a light source along the light guide so as to illuminate an inside of the tubular component; iii) detecting light that passes from the inside of the tubular component through at least one radial perforation using a microscope or camera; and iv) rotating the tubular component around the longitudinal axis so as to allow further radial perforations to be inspected by the microscope or camera.

[0037] The method of this aspect of the present invention allows tubular components to be inspected at-line, with minimal delay, and can help to provide an early indication in the event that the radial perforations are being imperfectly formed in the manufacturing process without having to send sample tubular components to a remote laboratory for time-consuming CT scanning. This reduces the risk of a large number of imperfect tubular components being manufactured before a problem is identified.

[0038] An imperfectly formed radial perforation may be a radial perforation that does not extend cleanly through an entire thickness of a wall of the tubular component. An imperfectly formed radial perforation may be a radial perforation that has a diameter that does not fall within predetermined tolerances. An imperfectly formed radial perforation may be a radial perforation that does not extend through a wrapper provided circumferentially around the tubular component.

[0039] The tubular component may be rotatably held in a sample holder. The sample holder may comprise a tubular aperture, and the tubular component may be rotatably held in the tubular aperture. The tubular aperture may be provided with a spring bushing, and wherein tubular component may be rotatably held by the spring bushing. In this way, it is possible to rotate the tubular component around the light guide so as to enable inspection of the radial perforations around the entire circumference of the tubular component from a given line of sight.

[0040] The tubular component may be rotated around the longitudinal axis by a rotation mechanism. The rotation mechanism may comprise a gearing mechanism. This may facilitate accurate fine rotational control when rotating the tubular component. It will be appreciated that accurate alignment of a radial perforation with respect to a light path from the light guide is important, and direct rotation of the tubular component, for example by way of an operator’s fingers, may not be sufficiently accurate. Accordingly, a rotation mechanism, for example a gearing mechanism, that provides a velocity ratio greater than one will allow improved fine rotational control.

[0041] The rotation mechanism may be manually operated to rotate the tubular component.

[0042] The rotation mechanism may be operated by an electric motor to rotate the tubular component. The electric motor may be a servomotor. The electric motor may be a stepper motor. The stepper motor may rotate the tubular component stepwise through a rotational angle corresponding to an angle subtended by two radial perforations, for example two circumferentially-adjacent radial perforations. The electric motor may be controlled by an actuator switch.

[0043] Light may be directed from the light source to the light guide along an optical fibre cable, and the light guide may comprise a radiating tip portion of the optical fibre cable. The radiating tip portion may have a longitudinal axis coincident with or parallel to the longitudinal axis of the tubular component. The radiating tip portion may be configured to emit light substantially radially from the longitudinal axis of the radiating tip portion.

[0044] The radiating tip portion of the optical fibre cable may extend from a substantially rigid termination portion of the optical fibre cable. The radiating tip portion may be substantially rigid. This may help to keep the radiating tip portion correctly aligned when inserted into the tubular component.

[0045] The optical fibre cable may have a connecting end portion at an end of the optical fibre cable remote from the radiating tip portion. The connecting end portion of the optical fibre cable may be optically connected to the light source. The light source may be external to the housing of the inspection device. The light source may be internal to the housing of the inspection device.

[0046] A portion of the optical fibre cable between the radiating tip portion and the remote connecting end portion may be disposed within a substantially cylindrical housing. The substantially cylindrical housing is preferably substantially impermeable to light. This may promote total internal reflection in the optical fibre cable. The cylindrical housing may comprise two semi-cylindrical components that are attached to each other around the optical fibre cable.

[0047] The light guide may emit light from the longitudinal axis in all radial directions.

[0048] The light guide may emit light from the longitudinal axis in only a predetermined sector of radial directions. An angle subtended by the sector of radial directions may be less than 90 degrees, optionally less than 45 degrees, optionally less than 25 degrees, optionally less than 10 degrees. In this way, it may be possible to concentrate the emitted light in a direction generally towards an optical detector, for example a camera or a microscope. Light passing from the inside of the tubular component through the at least one radial perforation may form an image in an image plane of the microscope or camera.

[0049] The at least one radial perforation may be determined to be satisfactory if the image comprises a light area surrounding a central dark area. The at least one radial perforation may be determined to be satisfactory if the image comprises a light area surrounding a central dark area, the central dark area having a well-defined peripheral edge.

[0050] The at least one radial perforation may be determined to be unsatisfactory if the image comprises a light area without a central dark area. The at least one radial perforation may be determined to be unsatisfactory if the image comprises a light area without a central dark area having a well-defined peripheral edge.

[0051] The at least one radial perforation may be determined to be satisfactory if the image has a well-defined peripheral edge. The at least one radial perforation may be determined to be unsatisfactory if the image has a blurred peripheral edge.

[0052] By detecting light passing through the radial perforations and examining characteristics of a pattern or image formed by the light on a detection plane of the camera or microscope, it is possible to determine whether or not a given radial perforation meets desired quality criteria. For example, when a given radial perforation correctly extends through an entire wall thickness of the tubular component, and also through any circumferential wrapper that may be present, light passing through the radial perforation from the light guide may form an image on the detection plane comprising a light area with a central dark area having a well-defined peripheral edge. Conversely, when a given radial perforation does not correctly extend through the entire wall thickness of the tubular component, or does not extend cleanly or fully through any circumferential wrapper that may be present, light passing through the radial perforation from the light guide will form an image on the detection plane without a central dark area having a well-defined peripheral edge. This is because the light will tend to scatter more in the event of obstructions or constrictions in the radial perforation, giving rise to a more evenly illuminated light area in the image. Obstructions or constrictions in the radial perforations both in the body of the tubular component and in any wrapper that may be provided around the tubular component may thus be detected.

[0053] In the context of the present disclosure, the term “camera or microscope” is intended to mean any device that is configured to form an image on an image plane for inspection by a human or a computer.

[0054] In the context of the present disclosure, the term “inner lumen” is intended to mean a central longitudinal passageway of a tubular component.

[0055] In the context of the present disclosure, the term “light guide” is intended to mean an element along which light travels lengthwise before being emitted in a direction generally transverse to the lengthwise direction. A light guide may be or may be part of an optical fibre cable, a silica element, a plastic optical fibre, an acrylic resin element, a polymethyl methacrylate element, a polycarbonate element, a glass element, a silicone element, a liquid crystal element, an epoxy resin element, a sapphire element, a quartz element, or a photonic crystal waveguide.

[0056] In the context of the present disclosure, the term “light source” is intended to mean a source of light that is optically configured to transmit light along and out of the light guide. The light source may be a light emitting diode, an organic light emitting diode, an incandescent bulb, a halogen bulb, an electroluminescent wire, a xenon bulb, a laser diode, a laser, or surface mount device light emitting diode.

[0057] In the context of the present disclosure, the term “radial perforation” is intended to mean a small diameter hole that extends from an inner lumen of a tubular component to an outer circumference of the tubular component in a radial direction.

[0058] In the context of the present disclosure, the term “tubular component” is intended to mean a component of an aerosol-generating article that has the overall form of a hollow cylinder or tube. The tubular component may, for example, be a fine hollow acetate tube (FHAT) component, a hollow acetate tube (HAT) component, a cardboard tube component, or a polylactic acid (PLA) tube component. Such tubular components may be employed as aerosol-cooling components in an aerosol-generating article, and are provided with radial perforations in order to permit ingress of ambient cooling air when a user draws on the aerosol-generating article by sucking or inhaling at a mouthpiece end of the aerosol-generating article.

[0059] 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.

[0060] Example Ex1 : An inspection device for inspecting radial perforations in a tubular component of an aerosol-generating article, the device comprising: a housing comprising an illumination device, the illumination device including a light guide that extends out of the housing; wherein the light guide is configured to be inserted into the tubular component along the longitudinal axis of the tubular component and is operable to transmit light from the illumination device to an inside of the tubular component.

[0061] Example Ex2: The device according to Example Ex1 , further comprising a sample holder configured to hold the tubular component such that the tubular component is rotatable about a longitudinal axis of the tubular component.

[0062] Example Ex3: The device according to Example Ex2, wherein the sample holder is connected to the housing by a bridge portion.

[0063] Example Ex4: The device according to Example Ex3, wherein the bridge portion connects a lower part of the sample holder to a lower part of the housing so as to define an inspection gap above the bridge portion between the sample holder and the housing. Example Ex5: The device according to any one of Examples Ex2 to Ex4, wherein the sample holder comprises a tubular aperture configured to receive the tubular component.

[0064] Example Ex6: The device according to Example Ex5, wherein the tubular aperture is provided with a spring bushing configured rotatably to hold the tubular component.

[0065] Example Ex7: The device according to Example Ex5 or Ex6, wherein the tubular aperture has a longitudinal axis that is substantially coincident with the longitudinal axis of the tubular component when the tubular component is received in the tubular aperture.

[0066] Example Ex8: The device according to Example Ex7, wherein the longitudinal axis of the tubular aperture is substantially coincident with a longitudinal axis of the light guide.

[0067] Example Ex9: The device according to Example Ex4 or any one of Examples Ex5 to Ex8 depending from Example Ex4, wherein the light guide is configured to be inserted into at least a portion of the tubular component that is disposed within the inspection gap when the tubular component is held by the sample holder.

[0068] Example Ex10: The device according to any one of Examples Ex2 to Ex9, further comprising a rotation mechanism configured to rotate the tubular component about the longitudinal axis of the tubular component when the tubular component is rotatably held by the sample holder.

[0069] Example Ex11: The device according to Example Ex10, wherein the rotation mechanism is a manually operated mechanism.

[0070] Example Ex12: The device according to Example Ex10, wherein the rotation mechanism comprises an electric motor.

[0071] Example Ex13: The device according to Example Ex12, wherein the electric motor is a servomotor.

[0072] Example Ex14: The device according to Example Ex12 or Ex13, wherein the electric motor is a stepper motor.

[0073] Example Ex15: The device according to any one of Examples Ex12 to Ex14, wherein the electric motor is controlled by an actuator switch.

[0074] Example Ex16: The device according to any preceding Example, wherein the illumination device comprises an optical fibre cable and wherein the light guide comprises a radiating tip portion of the optical fibre cable.

[0075] Example Ex17: The device according to Example Ex16, wherein the radiating tip portion of the optical fibre cable extends from a substantially rigid termination portion of the optical fibre cable.

[0076] Example Ex18: The device according to Example Ex16 or Ex17, wherein the optical fibre cable has a connecting end portion at an end of the optical fibre cable remote from the radiating tip portion. Example Ex19: The device according to Example Ex18, wherein the connecting end portion of the optical fibre cable is configured for optical connection to a light source.

[0077] Example Ex20: The device according to Example Ex19, wherein a portion of the optical fibre cable between the radiating tip portion and the remote connecting end portion is disposed within a substantially cylindrical housing that forms part of a body of the illumination device.

[0078] Example Ex21: The device according to Example Ex20, wherein the cylindrical housing comprises two semi-cylindrical components that are attached to each other around the optical fibre cable.

[0079] Example Ex22: The device according to any one of Examples Ex1 to Ex15, wherein the illumination device includes a light source.

[0080] Example Ex23: The device according to any preceding Example, wherein the light guide is configured to emit light from the longitudinal axis in all radial directions.

[0081] Example Ex24: The device according to any one of Examples Ex1 to Ex22, wherein the light guide is configured to emit light from the longitudinal axis in only a predetermined sector of radial directions.

[0082] Example Ex25: The device according to Example Ex24, wherein an angle subtended by the sector of radial directions is less than 90 degrees, optionally less than 45 degrees, optionally less than 25 degrees, optionally less than 10 degrees.

[0083] Example Ex26: The device according to any preceding Example, in combination with a microscope or camera configured to detect light passing through the radial perforations in the tubular component from the light guide.

[0084] Example Ex27: The device according to Example Ex26 depending through Example Ex4, wherein the microscope or camera is disposed over or adjacent to the inspection gap.

[0085] Example Ex28: A method of inspecting radial perforations in a tubular component of an aerosol-generating article, the method comprising the steps of: i) inserting a light guide into the tubular component along a longitudinal axis of the tubular component; ii) directing light from a light source along the light guide so as to illuminate an inside of the tubular component; iii) detecting light that passes from the inside of the tubular component through at least one radial perforation using a microscope or camera; and iv) rotating the tubular component around the longitudinal axis so as to allow further radial perforations to be inspected by the microscope or camera.

[0086] Example Ex29: The method according to Example Ex28, wherein the tubular component is rotatably held in a sample holder. Example Ex30: The method according to Example Ex29, wherein the sample holder comprises a tubular aperture, and wherein the tubular component is rotatably held in the tubular aperture.

[0087] Example Ex31 : The method according to Example Ex30, wherein the tubular aperture is provided with a spring bushing, and wherein the tubular component is rotatably held by the spring bushing.

[0088] Example Ex32: The method according to any one of Examples Ex28 to Ex31 , wherein the tubular component is rotated around the longitudinal axis by a rotation mechanism.

[0089] Example Ex33: The method according to Example Ex32, wherein the rotation mechanism is manually operated to rotate the tubular component.

[0090] Example Ex34: The method according to Example Ex32, wherein the rotation mechanism is operated by an electric motor to rotate the tubular component.

[0091] Example Ex35: The method according to Example Ex34, wherein the electric motor is a servomotor.

[0092] Example Ex36: The method according to Example Ex34 or Ex35, wherein the electric motor is a stepper motor.

[0093] Example Ex37: The method according to any one of Examples Ex34 to Ex36, wherein the electric motor is controlled by an actuator switch.

[0094] Example Ex38: The method according to any one of Examples Ex28 to Ex37, wherein light is directed from the light source to the light guide along an optical fibre cable, and wherein the light guide comprises a radiating tip portion of the optical fibre cable.

[0095] Example Ex39: The method according to Example Ex38, wherein the radiating tip portion of the optical fibre cable extends from a substantially rigid termination portion of the optical fibre cable.

[0096] Example Ex40: The method according to Example Ex38 or Ex39, wherein the optical fibre cable has a connecting end portion at an end of the optical fibre cable remote from the radiating tip portion.

[0097] Example Ex41 : The method according to Example Ex40, wherein the connecting end portion of the optical fibre cable is optically connected to the light source.

[0098] Example Ex42: The method according to Example Ex41 , wherein a portion of the optical fibre cable between the radiating tip portion and the remote connecting end portion is disposed within a substantially cylindrical housing.

[0099] Example Ex43: The method according to Example Ex41 , wherein the cylindrical housing comprises two semi-cylindrical components that are attached to each other around the optical fibre cable.

[0100] Example Ex44: The method according to any one of Examples Ex28 to Ex44, wherein the light guide emits light from the longitudinal axis in all radial directions. Example Ex45: The method according to any one of Example Ex28 to Ex44, wherein the light guide emits light from the longitudinal axis in only a predetermined sector of radial directions.

[0101] Example Ex46: The method according to Example Ex45, wherein an angle subtended by the sector of radial directions is less than 90 degrees, optionally less than 45 degrees, optionally less than 25 degrees, optionally less than 10 degrees.

[0102] Example Ex47: The method according to any one of Examples Ex28 to Ex46, wherein light passing from the inside of the tubular component through the at least one radial perforation forms an image in an image plane of the microscope or camera.

[0103] Example Ex48: The method according to Example Ex47, wherein the at least one radial perforation is determined to be satisfactory if the image comprises a light area surrounding a central dark area.

[0104] Example Ex49: The method according to Example Ex47 or Ex48, wherein the at least one radial perforation is determined to be unsatisfactory if the image comprises a light area without a central dark area.

[0105] Example Ex50: The method according to Example Ex47, wherein the at least one radial perforation is determined to be satisfactory if the image comprises a light area surrounding a central dark area, the central dark area having a well-defined peripheral edge.

[0106] Example Ex51 : The method according to Example Ex47 or Ex50, wherein the at least one radial perforation is determined to be unsatisfactory if the image comprises a light area without a central dark area having a well-defined peripheral edge.

[0107] Example Ex52: The method according to Example Ex47, wherein the at least one radial perforation is determined to be satisfactory if the image has a well-defined peripheral edge.

[0108] Example Ex53: The method according to Example Ex47 or Ex52, wherein the at least one radial perforation is determined to be unsatisfactory if the image has a blurred peripheral edge.

[0109] Examples will now be further described with reference to the figures in which:

[0110] Figure 1 shows a close-up view of a multi-segment tobacco article with a line of perforations visible on an outer wrapper;

[0111] Figure 2 shows a complete view of a multi-segment tobacco article with a line of perforations visible on an outer wrapper;

[0112] Figure 3 shows a computerised tomography (CT) scan of a cross section through the perforated part of the article of Figure 2;

[0113] Figure 4 shows a schematic cross-sectional view of an inspection device;

[0114] Figure 5 shows a schematic perspective view of an inspection device;

[0115] Figure 6 shows a detailed schematic cross-sectional view of an inspection device including a tubular component of an aerosol-generating article;

[0116] Figure 7 shows a detailed schematic cross-sectional view of an inspection device omitting the tubular component of an aerosol-generating article but including an illumination device; Figures 8 and 9 show the assembly of an illumination device;

[0117] Figure 10 shows a tobacco component of an aerosol-generating article being removed from a tubular component of the aerosol-generating article;

[0118] Figure 11 shows a detailed schematic cross-sectional view of an inspection device including a tubular component of an aerosol-generating article and an illumination device;

[0119] Figure 12 shows an image generated by the inspection device when a perforation meets specifications;

[0120] Figure 13 shows an image generated by the inspection device when a perforation does not meet specifications; and

[0121] Figure 14 is a schematic outline of an inspection device indicating exemplary dimensions.

[0122] Figure 4 shows a schematic cross-sectional view of an inspection device 10. The inspection device 10 comprises a sample holder 12 configured to hold a tubular component (not shown in Figure 4) such that the tubular component is rotatable about a longitudinal axis A. The sample holder 12 comprises a tubular aperture 13 configured to receive the tubular component. The inspection device 10 further comprises a housing 14 connected to the sample holder 12 by a bridge portion 17. The bridge portion 17 connects a lower part of the sample holder 12 to a lower part of the housing 14 so as to define an inspection gap 11 above the bridge portion 17 between the sample holder 12 and the housing 14. The housing 14 comprises a chamber 15 configured to receive an illumination device (not shown in Figure 4). One end of the chamber 15 communicates with the inspection gap 11 by way of an aperture 142. The aperture 142 extends from the one end of the chamber 15 to an outer wall 141 of the housing 14 at the inspection gap 11. In the illustrated embodiment, the tubular aperture 13, the aperture 142 and the chamber 15 are all aligned along the longitudinal axis A.

[0123] In alternative embodiments, the bridge portion 17 may be omitted, and the sample holder 12 and housing 14 may be mounted on a common substrate or may be separate free-standing components.

[0124] Figure 5 shows a schematic perspective view of an inspection device 10 similar to that of Figure 4, with parts labelled as for Figure 4. The embodiment of Figure 5 additionally comprises a spring bushing 16 incorporated in the tubular aperture 13. The spring bushing 16 may provide a compressing action on a tubular component (not shown) being held in the tubular aperture 13 of the sample holder 12, while still allowing the tubular component to be rotated about its longitudinal axis. The spring bushing 16 may be constructed with a gripping material that provides sufficient friction to retain the tubular component. The tubular component may be rotated about its longitudinal axis by rotating the spring bushing 16, for example by way of a rotating knob (not shown) connected to the spring bushing 16. Alternatively, sufficient rotational force may be applied to the tubular component by a skilled operator so as to overcome the friction between the spring bushing 16 and a circumferential surface of the tubular component, thus allowing the tubular component to be rotated about its longitudinal axis.

[0125] Figure 6 shows a detailed schematic cross-sectional view of an inspection device 10 similar to that of Figures 4 and 5, with parts labelled as for Figures 4 and 5. Figure 6 additionally shows a tubular component 100 of an aerosol-generating article 1 having a region 101 with radial perforations. The tubular component 100 is rotatably held in the tubular aperture 13 by way of the spring bushing 16 with the perforated region 101 extending across the inspection gap 11. One end of the tubular component 100 may abut the outer wall 141 of the housing 14 when the tubular component 100 is inserted fully through the tubular aperture 13 of the sample holder 12. In the embodiment of Figure 6, the inspection device is further provided with an electric motor 22, which may be a servomotor or a stepper motor. The electric motor 22 may be located adjacent to the bridge portion 17. The electric motor 22 may be provided with a mounting bracket 21 and a driveshaft 23 of the electric motor 22 may extend through the mounting bracket 21 to a gearwheel 24. The gearwheel 24 may in turn drive one or more further gearwheels 25 that serve to rotate the spring bushing 16 and thus also to rotate the tubular component 100 about its longitudinal axis. Through appropriate selection of the gearwheels 24 and 25, it is possible to obtain a velocity ratio greater than one, so that a relatively large rotation of the driveshaft 23 results in a relatively small rotation of the spring bushing 16 and the tubular component 100. This allows for very precise rotational control. The electric motor 22 is operated by an actuator switch 26. In embodiments where the electric motor 22 is a stepper motor, actuation of the actuator switch 26 can be used to cause a rotation of the tubular component 100 about its longitudinal axis through a precisely controlled predetermined angle, in either a forward or a reverse direction as required. The stepper motor may be configured for micro stepping, enabling a gradual rotation of the tubular component 100 in fine increments in either direction.

[0126] Figure 7 shows the inspection device of Figure 6 with the tubular component 100 omitted for clarity. Figure 7 shows an illumination device 40 inserted into the cavity 15 of the housing 14. A light guide 41 of the illumination device 40 extends out of the housing 14, through the aperture 143, in a direction towards the sample holder 12. The light guide 41 is configured for insertion into the tubular component 100 (see Figure 6) along the longitudinal axis of the tubular component 100 when the tubular component 100 is held in the sample holder 12.

[0127] The light guide 41 may be configured to emit light in all radial directions, or may be configured to emit light only in a range of radial directions, for example upwardly away from the bridge portion 17. The light emitted by the light guide 41 can pass through the radial perforations in the region 101 of the tubular component 100, and can be examined by way of a camera or microscope so as to determine a quality of the perforations, as will be described hereinbelow.

[0128] Figures 8 and 9 show how an exemplary illumination device 40 may be assembled. As shown in Figure 8, the illumination device 40 of an embodiment may comprise an optical fibre cable 42 having substantially rigid termination end 44 from which the light guide 41 extends. The light guide 41 may include a radiating tip portion 45. A connecting end 43 of the optical fibre cable 42, remote from the light guide 41 , is configured to receive light from a light source (not shown), which may be an LED or a laser or the like. A portion of the optical fibre cable 42, including the termination end 44, is enclosed between a pair of semi-cylindrical components 46 that together form a cylindrical housing that is configured to be received in the chamber 15 of the inspection device 10. The semi-cylindrical components 46 may be connected to each other by way of fasteners 47, for example screws or bolts. The assembled illumination device 40 is shown in Figure 9, with the light guide 41 and the radiating tip portion 45 extending from the cylindrical housing. The light guide 41 may be held in a substantially rigid configuration by the cylindrical housing so as to facilitate insertion into the tubular component 100 when the inspection device 10 is assembled for use.

[0129] In alternative embodiments, the illumination device 40 may comprise a cylindrical casing that fits into the chamber 15, the cylindrical casing including a light source such as an LED or a laser, and optionally a power source and power circuitry, with a light guide 41 extending from one end of the cylindrical casing so as to guide light from the light source into the tubular component 100 when the inspection device 10 is assembled for use.

[0130] Figure 10 shows an aerosol-generating article 1 , which may be a conventional cigarette or a heat-not-burn type aerosol-generating article, comprising multiple segments including a tubular component 100 with radial perforations 2, and a segment 110 comprising an aerosol-generating substrate. The aerosol-generating substrate segment 110 is removed so as to expose an end of the tubular component 100 including the radial perforations 2. The tubular component 100 may have a longitudinally-extending inner lumen (not shown in Figure 10).

[0131] Figure 11 shows the tubular component 100 of Figure 10 inserted into and held by the tubular aperture 13 of the sample holder 12 of an inspection device 10. A region 101 of the tubular component 100 comprising the radial perforations 2 is disposed in the inspection gap 11. An illumination device 40, for example as shown in Figures 7 and 9, is disposed in the cavity 15 of the housing 14. The illumination device 40 may be secured in the cavity 15 by way of a screw or bolt 48. The light guide 41 extends from the illumination device 40 into the longitudinally- extending inner lumen of the tubular component 100 so as to allow light to be emitted towards a circumferential wall of the inner lumen in the region of the radial perforations 2. When the tubular component 100 is inserted fully through the tubular aperture 13 so that one end of the tubular component abuts the housing 14, the light guide 41 , or at least a radiating tip 45 of the light guide 41 , will penetrate the tubular component 100 to a distance sufficient to ensure that light can be emitted towards the radial perforations 2. The tubular component 100 is then rotated about its longitudinal axis by operating the electric motor 22, controlled by actuator switch 26. The electric motor 22 has a driveshaft 23 and a mounting bracket 21. The driveshaft 23 is operable to rotate the tubular component 100 by way of gearwheels 24, 25. A camera or microscope (not shown in Figure 11) is positioned above the inspection gap 11 to examine light that passes from the light guide 41 , or at least the radiating tip 45 of the light guide 41 , through the radial perforations 2. Rotation of the tubular component 100 about its longitudinal axis allows all of the radial perforations to be inspected with having to move the camera or microscope.

[0132] Figure 12 shows an image formed at an image plane of a camera or microscope positioned above the inspection gap 12 of the inspection device 10 of Figure 11 when light passes through a correctly-formed and correctly-dimensioned radial perforation 2. It can be seen that the image comprises a lighter outer area 50 surrounding a darker central area 51. The darker central area 51 has a distinct peripheral edge with a high contrast visible against a brighter background formed by the lighter outer area 50, indicating that the radial perforation 2 extends cleanly through the entire circumferential wall of the tubular component 100.

[0133] Conversely, Figure 13 shows an image formed at an image plane of a camera or microscope positioned above the inspection gap 12 of the inspection device 10 of Figure 11 when light passes through an incorrectly-formed or incorrectly-dimensioned radial perforation 2. It can be seen that the image comprises a lighter area 50 of illumination without a darker central area having a distinct peripheral edge. This is caused by scattering of light within the incorrectly- formed or incorrectly-dimensioned radial perforation 2, or where the radial perforation 2 does not correctly pass through an outer wrapper.

[0134] It will be appreciated that different types of tubular component 100 may have different numbers of radial perforations 2. For example, some tubular components 100 may have nine radial perforations 2 disposed circumferentially, while other tubular components 100 may have eleven radial perforations 2. Other numbers of radial perforations 2 are also possible. The electric motor 22 may be configured to rotate the tubular component 100 rapidly about its longitudinal axis through a predetermined angle between successive radial perforations 2, depending on the expected number of perforations, while also allowing fine rotational control when required to get a good image at the camera or microscope.

[0135] In an exemplary, compliant, tubular component 100, the radial perforations 2 are evenly distributed around a circumference of the tubular component 100. Each radial perforation may have a diameter of around 0.13 millimetres to a tolerance of ±0.04 millimetres.

[0136] To give a sense of scale, and without intending to be limiting, Figure 14 shows a schematic outline of an inspection device 10 indicating exemplary dimensions:

[0137] A: 3 millimetres to 10 millimetres, preferably 5 millimetres to 8 millimetres, preferably

[0138] 5 millimetres

[0139] B: 5 millimetres to 10 millimetres, preferably 6 millimetres to 9 millimetres, preferably

[0140] 7.5 millimetres C: 5 millimetres to 10 millimetres, preferably 6 millimetres to 9 millimetres, preferably

[0141] 8 millimetres

[0142] D: 15 millimetres to 25 millimetres, preferably 17 millimetres to 23 millimetres, preferably 20.2 millimetres

[0143] E: 40 millimetres to 60 millimetres, preferably 42 millimetres to 58 millimetres, preferably 50 millimetres

[0144] F: 45 millimetres to 65 millimetres, preferably 50 millimetres to 60 millimetres, preferably 55 millimetres

[0145] 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

CLAIMS:

1. An inspection device for inspecting radial perforations in a tubular component of an aerosol-generating article, the device comprising: a housing comprising an illumination device, the illumination device including a light guide that extends out of the housing; and a sample holder configured to hold the tubular component such that the tubular component is rotatable about a longitudinal axis of the tubular component; wherein the light guide is configured to be inserted into the tubular component along the longitudinal axis of the tubular component and is operable to transmit light from the illumination device to an inside of the tubular component when the tubular component is held by the sample holder; and further comprising an optical detector configured to detect light passing through the radial perforations in the tubular component from the light guide.

2. The device according to claim 1 , wherein the sample holder is connected to the housing by a bridge portion, and wherein the bridge portion connects a lower part of the sample holder to a lower part of the housing so as to define an inspection gap above the bridge portion between the sample holder and the housing.

3. The device according to claim 1 or 2, wherein the sample holder comprises a tubular aperture configured to receive the tubular component.

4. The device according to claim 3, wherein the tubular aperture is provided with a spring bushing configured rotatably to hold the tubular component.

5. The device according to claim 2 or claim 3 or 4 depending from claim 2, wherein the light guide is configured to be inserted into at least a portion of the tubular component that is disposed within the inspection gap when the tubular component is held by the sample holder.

6. The device according to any preceding claim, further comprising a rotation mechanism configured to rotate the tubular component about the longitudinal axis of the tubular component when the tubular component is rotatably held by the sample holder.

7. The device according to claim 6, wherein the rotation mechanism comprises an electric motor.

8. The device according to any preceding claim, wherein the illumination device comprises an optical fibre cable and wherein the light guide comprises a radiating tip portion of the optical fibre cable.

9. The device according to claim 8, wherein the optical fibre cable has a connecting end portion at an end of the optical fibre cable remote from the radiating tip portion, and wherein the connecting end portion of the optical fibre cable is configured for optical connection to a light source.

10. The device according to any preceding claim, wherein the optical detector comprises a microscope or camera configured to detect light passing through the radial perforations in the tubular component from the light guide.

11. A method of inspecting radial perforations in a tubular component of an aerosol-generating article, the method comprising the steps of: i) inserting a light guide into the tubular component along a longitudinal axis of the tubular component; ii) directing light from a light source along the light guide so as to illuminate an inside of the tubular component; iii) detecting light that passes from the inside of the tubular component through at least one radial perforation using a microscope or camera; and iv) rotating the tubular component around the longitudinal axis so as to allow further radial perforations to be inspected by the microscope or camera.

12. The method according to claim 11 , wherein the tubular component is rotatably held in a sample holder.

13. The method according to claim 12, wherein the tubular component is rotated around the longitudinal axis by a rotation mechanism, and wherein the rotation mechanism is operated by an electric motor to rotate the tubular component.

14. The method according to any one of claims 11 to 13, wherein light is directed from the light source to the light guide along an optical fibre cable, and wherein the light guide comprises a radiating tip portion of the optical fibre cable.

15. The method according to any one of claims 11 to 14, wherein light passing from the inside of the tubular component through the at least one radial perforation forms an image in an image plane of the microscope or camera.

Images