APPARATUS FOR ANALYSING A ROD-SHAPED SMOKING ARTICLE

Abstract

Apparatus for analysing a rod-shaped smoking article is disclosed. The apparatus comprises a source (10) of x-ray radiation arranged to irradiate an area of the article (30), one or more area image sensors (12) arranged to detect x-ray radiation from an area of the article and to produce two-dimensional image data therefrom, and a drive mechanism arranged to move the smoking article (30) or the sensor (12) in an axial direction. A processing unit (20) is arranged to process two-dimensional image data produced by the area image sensor (12) at a plurality of different axial positions and to produce an output in dependence thereon. The processing unit may be arranged to output a two-dimensional image to be displayed and/or to output processed dimensional or quality information.

Claims

1. Apparatus arranged to analyse a rod-shaped smoking article, the apparatus comprising: a source of x-ray radiation arranged to irradiate an area of the rod-shaped smoking article; an area image sensor arranged to detect x-ray radiation from an area of the rod-shaped smoking article and to produce two-dimensional image data therefrom; a drive mechanism arranged to move at least one of the rod-shaped smoking article or the area image sensor in an axial direction relative to the rod-shaped smoking article; and a processing unit arranged to process the two-dimensional image data produced by the area image sensor at a plurality of different axial positions and to produce an output in dependence thereon.

2. (canceled)

3. Apparatus according to claim 1, wherein the rod-shaped smoking article comprises at least one hidden feature.

4. Apparatus according to claim 1, wherein the area image sensor is arranged to image an area which is smaller than a length of the rod-shaped smoking article.

5. Apparatus according to claim 1, wherein the area image sensor comprises a flat panel x-ray detector.

6. Apparatus according to claim 1, wherein two or more area image sensors are disposed circumferentially about the rod-shaped smoking article, and the two or more area image sensors are arranged to image the rod-shaped smoking article simultaneously.

7. (canceled)

8. Apparatus according to claim 6, wherein the two or more area image sensors are irradiated by a single x-ray source.

9. (canceled)

10. Apparatus according to claim 1, wherein the processing unit is arranged to process an image produced without rotation of the rod-shaped smoking article.

11. Apparatus according to claim 1, wherein the processing unit is arranged to determine positional characteristics of the rod-shaped smoking article or components of the rod-shaped smoking article in three orthogonal directions.

12. Apparatus according to claim 1, wherein the processing unit is arranged to output at least one of: a two-dimensional image to be displayed processed dimensional information; or processed quality information.

13. Apparatus according to claim 1, wherein the processing unit is arranged to produce a composite two-dimensional image from the two-dimensional image data produced by the area image sensor at the plurality of different axial positions of the rod-shaped smoking article.

14. (canceled)

15. Apparatus according to claim 1, wherein the processing unit is arranged to perform an imaging algorithm which analyses variations in at least one of intensity or color in the two-dimensional image data.

16. Apparatus according to claim 1, wherein the processing unit is arranged to identify components of the rod-shaped smoking article in a two-dimensional image.

17. Apparatus according to claim 1, wherein the processing unit is arranged to determine one or more physical properties of the rod-shaped smoking article or a component of the rod-shaped smoking article.

18. (canceled)

19. Apparatus according to claim 1, wherein the processing unit is arranged to detect a defect in the rod-shaped smoking article.

20. (canceled)

21. (canceled)

22. Apparatus according to claim 1, further comprising a holder arranged to hold the rod-shaped smoking article, wherein the holder is arranged to hold a single smoking article.

23. (canceled)

24. Apparatus according to claim 1, wherein the drive mechanism is arranged such that the rod-shaped smoking article is not rotated relative to the area image sensor.

25. Apparatus according to claim 1, further comprising a control unit ter arranged to control operation of the drive mechanism, wherein the control unit is arranged to control the drive mechanism to move at least one of the rod-shaped smoking article or the area image sensor such that an area of interest of the rod-shaped smoking article is in a field of view of the area image sensor.

26. (canceled)

27. Apparatus according to claim 25, wherein the control unit is arranged to control the drive mechanism to move at least one of the rod-shaped smoking article or the area image sensor such that relative movement between the rod-shaped smoking article and the area image sensor is faster in some axial positions of the rod-shaded smoking article than in others axial positions of the rod-shaped smoking article.

28. Apparatus according to claim 1, wherein the processing unit is arranged to produce a composite image comprising at least one region with higher quality image data and at least one region with lower quality image data.

29. (canceled)

30. (canceled)

31. A method of analysing a rod-shaped smoking article, the method comprising: irradiating an area of the rod-shaped smoking article with x-ray radiation; detecting x-ray radiation from the area of the rod-shaped smoking article using an area image sensor and producing two-dimensional image data therefrom; moving the rod-shaped smoking article or the area image sensor in an axial direction; detecting x-ray radiation from another area of the rod-shaped smoking article and producing two-dimensional image data therefrom; and processing two-dimensional image data from a plurality of different axial positions and producing an output in dependence thereon.

Description

[0057] Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:

[0058] FIG. 1 shows an example of a heat-not-burn (HNB) stick;

[0059] FIG. 2 shows parts of a testing apparatus in an embodiment of the present invention;

[0060] FIG. 3 shows parts of the apparatus of FIG. 2 viewed from above;

[0061] FIG. 4 shows parts of an x-ray source;

[0062] FIG. 5 shows parts of a typical panel detector;

[0063] FIG. 6 shows a composite image of an HNB stick;

[0064] FIG. 7 shows composite images of an HNB stick which have been digitally processed to enhance contrast;

[0065] FIG. 8 shows two orthogonal images of part of an HNB stick;

[0066] FIG. 9 shows two orthogonal images of another part of an HNB stick.

[0067] FIG. 1 shows an example of a heat-not-burn (HNB) stick. Referring to FIG. 1, the stick 1 is generally rod-shaped (cylindrical) with a major longitudinal axis running through its centre. In this example, the y-axis is defined as lying in the longitudinal (axial) direction while the x- and z-axes are defined as lying in the radial directions of the rod-shaped stick.

[0068] The HNB stick 1 comprises a tobacco plug 2, a transfer tube 3 and a filter 4, all of which are wrapped in paper 5. Since the stick does not burn, the wrapping paper 5 may be thicker than in conventional cigarettes. A foil overwrap 6 may also be provided over part of the stick. The tobacco plug 2 may be leaf or reconstituted tobacco and may be shredded or crimped into a fluted form. The transfer tube 3 may be made of paper, plastic or formed acetate. The filter 4 may be made of polylactic acid (PLA) crimped in place, or monoacetate. Other physical components (not shown) may be present such as carbon blocks, flavour capsules, metal foils and so on. The stick may further include tipping paper and flavours such as menthol. It will be appreciated that the exact construction of a HNB stick will vary depending on the manufacturer, so this description is given by way of example rather than limitation.

[0069] In use, the consumer inserts the HNB stick into a separate heating device which contains an electronically controlled heater. Typically, a heated blade is inserted into the tobacco plug. The heated blade heats the tobacco to produce a vapour. The vapour is drawn through the transfer tube and the filter and inhaled by the consumer.

[0070] During manufacture of HNB sticks it is necessary to perform quality control to establish if the physical construction is as specified. Any defects may have a significant impact on consumer satisfaction and the delivery of nicotine and potentially harmful compounds to the consumer. Defects may be defined as, for example, missing elements, misplaced elements, gaps between elements, malformed elements, damaged elements etc. In all cases these may be hidden by the wrapping that surrounds the components of the HNB stick and so cannot be inspected using conventional callipers and inspection equipment unless the stick is disassembled.

[0071] Camera systems using visible light, such as those disclosed in WO 2004/083834, are known to be able to detect defects in conventional cigarettes. However, these systems are generally unsuitable for analysing HNB sticks which may have thick papers, outer metal foils, and little density differences between elements.

[0072] In embodiments of the present invention, radiation in the x-ray range of wavelengths, rather than visible or infrared, is used to perform quality control analysis. By changing the wavelength of radiation to the x-ray region it is possible for the radiation to penetrate the article under test. An image of the article can be generated using an area image sensor. This will provide image definition in two dimensions when the image is suitable processed digitally to enhance features of interest. This gives dimensional information in the x and y directions with a practical resolution of 0.05 mm or better from a single image frame.

[0073] For many applications, the cost of a large flat panel image sensor may be prohibitive. However, by moving the sample under examination laterally in front of a smaller detector the images can be assembled into a larger image. This has some disadvantages in that image construction is slow unless image quality is compromised. In embodiments of the invention this is overcome by fast scanning across the majority of the sample and then slow scanning across areas of interest in order to generate a high-resolution image.

[0074] In principle, the information gained from the image can be enhanced if the sample is rotated whilst a series of images are taken and a quasi-three dimensional image is built up of the HNB stick structure. This will enhance some component features such as the density of tobacco along the length of the stick or the radial positioning of inserted elements such as flavour capsules. However, in practice this may involve excessive waiting times, and it has been found that similar benefits can be obtained by simultaneously taking two images at 90° to one another or at another suitable angle. This gives information on the radial placement of objects such as capsules and foils as well as information about the concentricity of holes in tubes such as present when hollow acetate tubes are present in the construction of the HNB sticks. Imaging in this way at oblique angles can also give additional information on the density of packing of a component of the HNB stick such as the tobacco crimp.

[0075] FIG. 2 shows parts of a testing apparatus in accordance with an embodiment of the present invention. Referring to FIG. 2, the apparatus comprises an x-ray source 10, x-ray panel detectors 12, vacuum chuck 14, drive mechanism 16, control unit 18, processing unit 20, input device 21, display 22 and alarm unit 28. The vacuum chuck 14 is used to hold a sample 30 using a vacuum. This holds the sample 30 in position with respect to the source 10 and the detector 12. The drive mechanism 16 is positioned out of the line of sight of the x-ray source 10 and the panel detectors 12.

[0076] FIG. 3 shows parts of the apparatus of FIG. 2 when viewed from above. Referring to FIG. 3, in this example two x-ray panel detectors 12 are disposed at different positions circumferentially about the sample 30, and are held in place with holder 13. The x-ray source 10 is arranged to irradiate the sample 30 with a beam of x-ray radiation 31 such that each detector 12 receives radiation that has passed through or been reflected by the sample 30. The panel detectors 12 are each in a plane which is parallel to the axis of the sample 30, but at an angle to each other, so that each detector views a different area of the sample circumferentially. In this example the two detectors are substantially orthogonal (at 90°) to each other, although other angles may be used instead. Additional panel detectors may also be provided if desired.

[0077] FIG. 4 shows parts of the x-ray source 10 in one embodiment. Referring to FIG. 4, the x-ray source comprises filament 32, cathode 34, target 36, Beryllium window 38 and enclosure wall 40. In operation, the filament 32 is used to heat the cathode 34 to produce electrons 42. The electrons 42 are accelerated to a high velocity by the target (anode) 36, which is at a high voltage. The high velocity electrons collide with the target, creating the x-rays 44. The x-rays are emitted to the exterior via the Beryllium window 38.

[0078] The panel detectors 12 are flat panel x-ray detectors (area image sensors) of a type known in the art. Flat panel x-ray detectors are a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. The flat panel detectors detect x-ray radiation and convert it into electrical signals that represent an image. The detected radiation is radiation from the x-ray source 10 that has been subject to variable attenuation as it passes through or is reflected by the sample 30. The panel detectors may be of the CMOS (complementary metal-oxide-semiconductor) or CCD (charge-coupled device) type with appropriate scintillator devices, or any other appropriate type. The panel detectors typically include multiple functional blocks such as timing generators, vertical and horizontal shift registers, readout amplifier, A/D converters and low-voltage differential signalling (LVDS). This results in a digital signal with a high S/N ratio which makes the sensor panels easy to integrate into standard digital imaging tools. The panel detectors may incorporate a global shutter function that allows the synchronisation of the x-ray illumination timing to take a single shot of an image.

[0079] FIG. 5 shows parts of a typical panel detector. Referring to FIG. 5 the panel detector comprises photosensitive area 46, timing generator 48, vertical shift register 50, horizontal shift register 52, column CDS (correlated double sampling) circuit 54, image amplifier 56, and digital-to-analogue converter 58. The photosensitive area 46 in this example comprises 1000×1500 pixels and has an area of approximately 20 mm×30 mm, although of course other values could be used instead. In operation, the timing generator 48 is used to generate timing signals for the shift registers 50, 52 in order to read out data from the photosensitive area 46. The data is amplified by image amplifier 56 and converted into digital by analogue-to-digital converter 58 to produce the image data. Panel detectors such as those shown in FIG. 5 are known in the art and are typically used for intra-oral x-ray imaging in dental applications.

[0080] The panel detectors 12 are smaller than the sample under test so that a high-quality image can be taken of a small region of interest of the sample with a single exposure in a relatively short period of time. The distances between the source 10 and the sample 30, and between the sample 30 and the detectors 12, are optimised to give sufficient magnification of the image for the desired spatial resolution when considered with the image detector pixel size. Excessive magnification is avoided as there is a compromise regarding the exposure time which must be minimised to allow an analysis cycle time commensurate with the use of the equipment for Quality Assurance of a high-speed process.

[0081] Referring back to FIG. 2, the drive mechanism 16 comprises platform 23, drive motor 24, leadscrew 25 and positional encoder 26. The vacuum chuck 14 is attached to the platform 23, which is translated by means of the motor 24 and leadscrew 25. The leadscrew 25 is aligned with the axis of the sample 30, such that rotation of the motor 24 causes the sample to move axially with respect to the source 10 and the detectors 12. The control unit 18 is used to control the operation of the motor 24 in order to move the sample 30 into the appropriate position for imaging. The exact positional reference to the vacuum chuck is measured by the positional encoder 26 and sent to the control unit 18. The positional encoder 26 may be fitted either to the drive mechanism 16 or to the vacuum chuck 14 itself. The drive mechanism 16 under control of the control unit 18 can precisely translate the sample 30 by increments as measured by the encoder 26.

[0082] In operation, the sample 30 is first moved to a position in which an area of interest is in the field of view of the detectors 12. Images of the sample are then taken by the panel detectors 12 and transferred to the processing unit 20. The sample is then moved axially to another position. In this position another pair of images is taken and transferred to the processing unit 20. This process may be repeated for a number of different positions of the sample. Preferably, the sample is moved such that images are taken along its entire length, with each image abutting or overlapping with the next. If desired, certain parts of the sample may be imaged as the sample is moving and/or with a reduced exposure time compared to other parts. The processing unit 20 processes the various images to produce a composite image and/or to determine physical properties of components of the sample 30.

[0083] The control unit 18 and the processing unit 20 may both be implemented as software routines executing on a suitable processor, such as personal computer. The control unit 18 and the processing unit 20 are both connected to the input device 21. The input device may comprise, for example, a keyboard and/or mouse, and is used for inputting test parameters and controlling operation of the system. The processing unit 20 is connected to the display 22 for displaying the results of the analysis. The control unit may also be connected to the display in order to facilitate the input of parameters and control of the system.

[0084] The processing unit 20 includes a suitable imaging algorithm for producing a composite image based on the individual images of different areas of the sample. Once a composite image has been produced, further image processing algorithms may be applied. For example, different contrasts may be applied highlighting different features and defects in the sample under test.

[0085] The processing unit 20 is also arranged to analyse the individual images and/or the composite image to discern one or more features in the image. Typical imaging software utilises one or more known algorithms for detecting an edge of an object in a digital image. Such algorithms typically involve measuring contrast levels for defining a point at which an edge is defined as being present, and the length (in pixels) along the defined edge which is used to determine a contiguous and true edge, and involve statistical considerations to determine the probability that a detected edge is a true edge. Edges are detected by analysing horizontal and vertical region projections of the image. Bright spots corresponding to internal voids and the like are detected using basic segmentation techniques after the image has been “thresholded” using a bimodal histogram threshold detection algorithm. Examples of suitable imaging algorithms are disclosed in WO 2004/083834, the subject matter of which is incorporated herein by reference. In the arrangement described above, the drive mechanism 16 can precisely translate the sample 30 by increments as measured by the encoder to move a region of interest to the field of view of the detectors 12. At this point, two high quality images can be taken at orthogonal angles. Alternatively, a series of high quality images (relatively long exposure time) can be taken and overlaid to produce an image of greater quality.

[0086] During translation to a second or third region of interest it is possible to take lower quality images as the sample is moved. The processing unit 20 may overlay these with the high-quality images to form a composite image of the sample under test with critical regions of high quality for analysis and less critical areas having lower image quality and so of less detailed information. An example of the use of this lower quality image might be to determine the overall distribution of carbon in a so called Dalmatian filter (a filter with carbon dispersed within a cellulose acetate tow) over 120 mm length during filter production. The higher quality image might be used at the interface at two combined sections of rod where there might be a void of sub millimetre size caused by angled cutting of one of the elements, while the lower quality images might be used elsewhere.

[0087] The proposed techniques are a significant improvement over existing camera techniques in that the information needed can be obtained quickly, for example in 5 to 10 seconds as opposed to 30 to 60 seconds; they can provide detailed spatial information in the x and y directions; they are impervious to paper thickness of blocking elements such as foils; they can determine changes in density of materials (similar to microwave imaging); they can find included objects (for example foils or capsules), determine their form, determine their position, determine if they are damaged; and with suitable algorithms define segment lengths and gaps in segment elements.

[0088] The images can be suitably processed digitally to enhance contrast using known techniques. One or more of the following may be determined from a single image or pair of images: [0089] End cut angle of rod [0090] Length of components within HNB stick [0091] Diameter of components with HNB stick [0092] Gaps between components in HNB stick [0093] Presence of all elements in HNB stick [0094] Overwrap of tipping and envelope papers [0095] Density of tobacco fill along tobacco column [0096] Dense end offset of tobacco column (a parameter used in manufacturing tobacco columns to prevent hot coal fall out) [0097] Uniformity of reconstituted tobacco crimp [0098] Contamination from one component to another e.g. tobacco to hollow acetate tube (HAT) [0099] Uniformity of carbon distribution in “Dalmatian” filters [0100] Longitudinal and radial positioning of inserted elements in filters and tobacco columns e.g. foils and capsules [0101] Concentricity of inner and outer surfaces of HAT [0102] Wall thickness of HAT and paper tubes [0103] Integrity of capsules (burst/not burst) [0104] Count of inserts

[0105] Currently available techniques such as microwave scanning or optical imaging require multiple measurement techniques to be used to glean defect information or the defects may go undetected due to the difficulty of determining the presence or nature of any potential defect.

[0106] FIG. 6 shows an example composite image of an HNB stick. The composite image is obtained by “stitching” together images taken with the sample 30 at different positions with respect to the panel detectors 12. Referring to FIG. 6, it can be seen that different components of the stick, such as the tobacco plug, transfer tube, filter, wrapping paper and foil overwrap can be identified visually. Imaging algorithms in the processing unit 20 can also be used to identify the various components automatically. This is achieved by analysing variations in the intensity of the image, and comparing the variations in intensity to stored models. The edges of each component can be identified by the appropriate edge detection algorithms. Once the components and their edges have been identified, their dimensions can be measured by measuring the distances between the edges.

[0107] In FIG. 6, the lighter section between the tobacco plug and transfer tube indicates a gap between those components which is undesirable. The processing unit can identify any such gaps by detecting a lighter area between two components. The exact size of the gap can be determined through calibration against a precise size standard that converts pixels on the detector to distance in both x and y directions. This size standard can form part of the image if a calibrated graticule is included as a mask over the detector or as part of the sample holder.

[0108] FIG. 7 shows examples of composite images of an HNB stick which have been digitally processed to enhance contrast. In FIG. 7(A) a wide tone range filter has been applied to the image. In FIG. 7(B) a dark tone range filter has been applied. In FIG. 7(C) a wide tone range and a dynamic compression filter has been applied. Each of the filters of FIGS. 7(A) to 7(C) may enhance a particular property or feature of the HNB stick. In the examples of FIG. 7, a tobacco plug 64 and a hollow acetate tube (HAT) 66 can been seen, with different properties of these components being enhanced by the different filters.

[0109] FIG. 8 shows example images of an HNB stick with an inserted object taken with the panel detectors 12. In FIG. 8, the images show part of an HNB stick 60 with an inserted object 62. The inserted object in this example is a gelatine capsule filled with flavoured water. As indicated in FIG. 8, the imaging algorithms in the processing unit 20 can be used to measure various parameters such as the distance of the object from the end of the stick (y-location), the concentricity of the object (x- and z-locations), and the diameter of the object.

[0110] For example, in order to determine the y-location of the inserted object, the imaging algorithms first identify the end of the stick 60 and the centre of the object 62 by analysing variations in the intensity of the image. Once these points have been identified, the location of the object in the y-direction can be obtained by measuring the distance between the two. From FIG. 8 it can be seen that the inserted object can be located in the y-direction from a single image, although more accurate results may be obtained by using two or more images. Similar processing techniques can be used to measure the diameter of the object.

[0111] The concentricity of the object can be determined from the pair of images which are taken orthogonally to each other. Additionally, through measurement of the diameter of the capsule in two orthogonal directions it can be determined if the capsule is burst or damaged during processing. In the example shown in FIG. 8, the inserted capsule 62 has broken as can be seen from the right-hand side image.

[0112] FIG. 9 shows another example of two orthogonal images taken with the panel detectors 12. In FIG. 9, the images show a tobacco plug 64 and a hollow acetate tube (HAT) 66. As indicated in FIG. 9, the imaging algorithms in the processing unit 20 can be used to measure various parameters such as the outside diameter (OD) of the HAT and the inside diameter (ID) of the HAT. This can be achieved by identifying the edges of the HAT, and then measuring the appropriate distances between them, in a similar way to that described above. By using orthogonal images it is possible to determine the concentricity (uniformity of section) of the HAT.

[0113] Additionally, the density uniformity of the tobacco crimp can be determined by analysing the change in grey density in the orthogonal images. Similar techniques can be used to identify “bleed” from tobacco into other elements.

[0114] FIG. 9 also shows a lighter area between the tobacco plug 64 and the HAT 66 in the right-hand image. As in the example described above, this can be identified by the imaging algorithms by identifying a bright spot between the two components.

[0115] It will be appreciated that any other appropriate physical property of the HNB stick or a component thereof which is derivable from the image may be determined as well as or instead of those discussed above.

[0116] In any of the above embodiments, the imaging algorithms may be arranged to detected any defects in the sample, such as an unwanted gap, broken capsule, non-uniform tobacco crimp, migration of tobacco to HAT, lack of concentricity in the HAT, misplaced components, missing components, components not conforming to expected sizes, or any other unexpected or undesired physical property of the sample being determined. If any defects are detected, then this may be indicated to the user via the display 22, for example by highlighting the affected area or displaying a warning message. Alternatively or in addition an alarm signal may be output to alarm unit 28 which may output a visual and/or audible alarm, and/or be used to halt production of the HNB sticks.

[0117] It will be appreciated that embodiments of the present invention have been described above by way of example only, and modifications in detail will be apparent to the skilled person within the scope of the appended claims. For example, while embodiments of the invention have been described with reference to a HNB stick, the principles described herein may also be applied to the analysis of conventional cigarettes or any other rod-shaped article.