TWI657969B - Evaluating porosity distribution within a porous rod - Google Patents

Abstract

In a method for assessing the porosity distribution of a porous article such as a wrinkled filter, a tobacco stopper or a cigarette, a digital image of the cross-sectional area of the article is obtained and a plurality of Each of the size sub-regions determines the hole area ratio. This provides a plurality of pore area ratios. The plurality of pore area ratios allow the local porosity distribution within the cross-sectional area of the porous article to be evaluated. The calculated area ratio of each sub-region overlaps with at least one adjacent sub-region between 10% and 95%. The method used to quantitatively evaluate the porosity distribution can be used to control the process used to make the porous article.

Description

Assess porosity distribution in porous members

This specification relates to a method for evaluating a porosity distribution in a porous article. This specification may be particularly related to a method for evaluating the porosity distribution in the body of a smoking article such as a cigarette, or a rod formed from a bundle sheet, such as the porosity distribution in a filter.

The filter for smoking articles can be formed, for example, by a process of corrugating appropriate sheets and then bundling the materials together to form a continuous rod having holes along the longitudinal axis of the filter rod. The rod can then be cut to the appropriate length to form individual filter rod segments. The essence of this method means that the length of the filter rod segment can have a substantially uniform material weight distribution. Moreover, a set of filter rod segments produced by this method can have a very narrow weight distribution if they are cut to the same length. Even if the density and thickness of the sheet used to form the filter rod are substantially uniform throughout the width of the sheet and the change in overall porosity between the filter elements is small, the wrinkles in the filter element and the shape of the cluster sheet may still be very different This causes a great change in the distribution of the pore area ratio across the cross section of the filter element. The cross-sectional distribution of the pore area ratio of porous articles such as wrinkles and cluster filters can be conveniently referred to as "porous distribution" or "local porosity distribution". The width of the porosity distribution can be determined by the ratio of a plurality of pore areas Deviation indication. In general, if the pores have the same size and shape throughout the length of the porous article, the porous distribution measured according to the present invention will be the most representative of the entire porous article.

Such changes in the porosity distribution may significantly affect the efficiency of the filter element. For example, if the sheet is bundled into a rod such that a part of the cross-section of the rod is almost non-porous, and different parts of the cross-section of the rod are almost 100% porous, the filter may not be able to Works as expected. Properties such as pumping resistance may also be strongly affected by the local porosity distribution.

Some tobacco products, such as heated aerosol-generating articles, may include tobacco plugs, which are formed by crimping and bundling the treated tobacco sheet into a continuous rod and cutting the rod to a suitable length to form individual tobacco plugs Be formed. The structure of the tobacco stopper formed in this manner may be similar to that of a filter produced by corrugating and bundling an appropriate filter sheet. It is desirable to have low variability in the physical properties of the tobacco plugs with each other. Each of a batch of plugs preferably has a similar weight so that they contain a similar amount of tobacco material, and each should also have a similar internal morphology. The shape of the tobacco stopper may be important in determining how it functions optimally in heating the aerosol to produce tobacco products.

Conventional cigarettes can be formed by producing continuous rods of shredded tobacco wrapped in cigarette paper, and then cutting the continuous rods into appropriate lengths to form individual tobacco rods or rods in the form of cigarettes. A filter is typically applied to one end of the tobacco rod to form the final cigarette product. At least one end of the cigarette is a loose end or an open end, and the shreds contained in the rod body may fall out of the rod at this end. If the cigarette does not form the correct shred The density, the material is more likely to fall out of the open end, and the quality of this cigarette is low. One way to assess the amount of material that falls out of the end of a cigarette is to evaluate the porosity distribution of the cigarette at the open end.

A method for determining the uniformity of the porosity distribution in a porous article such as a porous rod can be useful in quantitatively determining and controlling the quality of products such as filters, tobacco plugs, and cigarettes.

EP0518141 discloses a method for determining when a pack of cigarettes is inappropriate, such as being improperly filled, broken or short. The disclosed method measures luminescence away from the end face from a pack of conventional cigarettes. Measure a signal corresponding to the amount of light received by each pixel of a light-sensitive sensor (for example, a CCD), and adjust the gray scale from 0-255. Draw the adjusted gray scale of the signal measured from each pixel, and calculate the standard deviation of the brightness measured from the cigarette pack to provide a threshold value to determine whether to reject the entire pack. EP0518141 does not determine the uniformity of the porosity distribution.

DE19753333 discloses a method for determining whether several batches of cigarettes are sufficiently filled. Signal intensity indicating the front end of a batch of cigarettes was measured using a CCD camera. The number of adjacent pixels below a certain threshold is considered as an indicator of an area with underfilled cigarettes. DE19753333 does not disclose a way to distinguish between holes that are evenly distributed throughout the tobacco rod and all holes are merged into one large hole or a large area that is not sufficiently filled with cigarettes.

EP0747855 discloses a method for enhancing digital images. Make most local histograms to improve visual local contrast in sub-regions of natural scene images.

In one aspect, a quantification method for evaluating the distribution of porosity in a porous article such as a porous member includes the steps of: obtaining a digital image of a cross-sectional area of the article; determining a plurality of cross-sectional areas of the article The pore area ratio in each of the child regions of the same size, thereby obtaining a plurality of pore area ratios; and using the plurality of pore area ratios to evaluate the pore area ratio in the cross-sectional area of the porous article of the article The cross-sectional distribution is also referred to herein as the porous distribution. Each sub-region overlaps with at least one adjacent sub-region preferably between 10% and 95%.

A quantitative method for assessing the distribution of porosity in a porous article such as a porous rod may include the following steps: obtaining a digital image of a cross-sectional area of the article; determining a plurality of children of the same size in the cross-sectional area of the article A hole area ratio in each of the regions, thereby obtaining a plurality of hole area ratios; and determining a standard deviation of the hole area ratio. In this case, the standard deviation of the pore area ratio indicates the width of the porosity distribution. Each sub-region overlaps with at least one adjacent sub-region preferably between 10% and 95%.

As used herein, "cross-sectional area of an article" refers to the area of an article in a plane substantially perpendicular to the longitudinal dimension of the article. For example, the article may be a rod and the cross-sectional area may be the cross-section of the rod taken along the rod rod at any length, or the cross-sectional area may be the end surface of the rod. The cross-sectional area need not be taken from a plane that is perpendicular to the longitudinal direction of the rod, but it is preferably within about 45 ° that is approximately perpendicular to the longitudinal direction of the rod. Preferably, the cross-sectional area is in a plane substantially perpendicular to the longitudinal direction of the rod.

As used herein, the term "pore" refers to the objectless area of a porous article. For example, the cross-sectional area of the corrugated filter includes a portion of the cluster sheet and a gap portion between the portions of the cluster sheet. In this case, the holes are related to the gaps between the sheets.

As used herein, the term "porosity" refers to the volume ratio of void space in a porous article.

As used herein, the term "overall porosity" refers to the entire cross-section of a porous article, such as the porosity of the cross-section of a porous member.

As used herein, the term "subregion" refers to an area in a cross-sectional area of an article that is smaller than the cross-sectional area of the article and includes at least a portion of the cross-sectional area of the article.

As used herein, the term "pore area ratio" refers to the porosity within a subregion. The pore area ratio is a measure of local porosity, that is, porosity within a subregion. Another term for pore area ratio may be local porosity.

As used herein, the term "porosity distribution" refers to the measurement of changes in the ratio of different pore areas. In other words, the porosity distribution is a quantitative measurement of the porosity distribution throughout the cross-sectional area of the article. As used herein, "porosity distribution" has the same meaning as "local porosity distribution". The width of the porosity distribution can be expressed as the standard deviation in a plurality of pore area ratios.

The local porosity distribution or porosity distribution can be calculated only from the pore area ratio of a single cross-sectional area constituting the article. The local porosity distribution of any individual item can be compared with another item. The local porosity distribution can be viewed as a measure of the porosity uniformity of an individual article. For example, if the area of multiple holes in an article is lower than the standard deviation, the holes in the article are It can be evenly distributed across the cross-sectional area of the article. However, if the area ratio of the plurality of holes of the article is higher than the standard deviation, the holes are not evenly distributed throughout the cross-sectional area of the article.

The local porosity distribution or porosity distribution can be calculated from the pore area ratio of the cross-sectional area from most different articles, such as a group of articles. The local porosity distribution from one set of items can be used to evaluate the quality of porosity between one set and another set of items.

As used herein, the terms "aerosol-generating article" and "smoke product" refer to an article that includes an aerosol-forming substrate capable of releasing volatile compounds that can form an aerosol. For example, the aerosol-generating article may be a smoking article that generates an aerosol that can be directly inhaled into the lungs of a user through the mouth of the user. Aerosol-generating articles are disposable.

The aerosol-generating article or smoking article may be a heated smoking article, which is a smoking article that includes an aerosol-forming substrate that is intended to be heated rather than burned to release volatile compounds that can form an aerosol. Aerosols formed by heating the aerosol-forming substrate may contain fewer harmful components than those produced by combustion or thermal degradation of the aerosol-forming substrate.

As used herein, the term "aerosol-forming matrix" refers to a matrix capable of releasing volatile compounds that can form an aerosol. Such volatile compounds can be released by heating the aerosol-forming matrix. The aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article. The aerosol-forming substrate may include or be in the form of a tobacco plug. For example, a tobacco plug formed from a homogeneous tobacco cluster sheet may form an aerosol-forming matrix or an aerosol-generating article.

As used herein, the term "wrinkled filter element" refers to a filter element formed by a process of wrinkling and bundling a filter sheet, such as a paper or polymer material, into a rod. The rod can be wrapped with packaging material. The creping filter has an open hole along the longitudinal direction of the rod.

As used herein, the term "tobacco plug" refers to a tobacco plug formed by a process of wrinkling and bundling a treated or homogenized tobacco sheet in the form of a rod. The clustered tobacco material may be overwrapped with a packaging material, such as cigarette paper, to form a tobacco stopper. The tobacco stopper has an open hole in the longitudinal direction of the rod.

The porous article may be a porous rod. As used herein, the term "porous member" refers to a member or material having open holes extending along the longitudinal dimension of the member. The porous rod may be a wrinkled filter, or a tobacco stopper or a conventional cigarette. The porous rod may have a diameter between 5 and 10 mm, such as about 7 mm or about 8 mm.

The step of obtaining a digital image of the cross-sectional area of the porous article can be performed by any suitable method. For example, a digital camera can be used to capture a cross-sectional area of a porous object, or a scanner can be used to scan. A conventional camera can be used to take a picture, and the resulting image can be scanned and converted into a digital image. The sub-regions of the cross-sectional area are areas that cover some, but not all, of the cross-sectional area. The area of the sub-region is smaller than the area of the cross-sectional area. The subregion must be large enough to represent the local morphology within the subregion. The subregions must also be small enough to detect local variations in porosity and density in the cross-sectional region. In some preferred embodiments, the width of the sub-region is between about one quarter and one tenth of the width of the porous article to be tested. In the cross-sectional area of the article, such as a tobacco plug or filter rod segment is substantially circular In the case, it is preferable that the sub-region of the rod is rectangular, and has a height and width of a series between one-fifth of the diameter of the plug and one-tenth of the plug, for example, one-sixth of the plug One or seventeenth of the diameter of the plug or one eighth of the diameter of the plug.

The pore area ratio of the sub-region is determined by dividing the pore area ratio in the sub-region by the total area of the sub-region. Thus, the hole area ratio is the area ratio within the sub-region, which represents the void divided by the total area of the sub-region.

Since the plurality of pore area ratios are each calculated from the same size sub-regions of the cross-sectional area, the plurality of pore area ratios can be used to evaluate the porosity distribution in the cross-sectional area of the porous article. For example, parameters such as the average hole area ratio, the highest hole area ratio, and the lowest hole area ratio may be determined from the plurality of hole area ratios. The standard deviation of the hole area ratio can be determined. The data on the porosity distribution can determine the uniformity in the cross-sectional area of the porous article. Since each sub-region overlaps at least one adjacent sub-region, it is ensured that a representative pore area ratio is determined for the entire cross-sectional area of the porous article.

Preferably, the digital image of the cross-sectional area is composed of a plurality of pixels, and each pixel constituting the cross-sectional area is included in at least one of the plurality of sub-areas. Preferably, the digital image of the cross-sectional area is at least 500 × 500 pixels.

It may be advantageous that each sub-region overlaps with at least one adjacent sub-region between 70% and 90%, for example, about 80%.

This method may include the step of calculating the standard deviation of the plurality of pore area ratios. The standard deviation of the pore area ratio can provide an indication of a uniform porosity distribution within a porous article.

This method can be performed on more than one porous article simultaneously. For example, a digital image can be obtained from each of a plurality of porous members that form or are referred to as a group of members, and the porosity distribution can be evaluated for the entire group of members. A digital image containing images of the cross-sectional area of a plurality of porous members can be obtained. In this case, the method can include detecting individual images of individual members and manipulating the images to exclude those that are not a plurality of porous members. A further step for pixels within a cross-sectional area of either.

It is particularly advantageous to obtain images simultaneously for a plurality of porous rods. For example, a plurality of cigarette end faces can be imaged, and an appropriate image processing software can be used to identify and select each individual end face, that is, an image of a cross section.

Preferably, the method is as automated as possible. For example, it is preferable to take the method steps such as determining the area, calculating the pore area ratio, and evaluating the porosity distribution as processing steps by performing an algorithm embodied in software.

This method can be particularly useful for determining the porosity distribution within a wrinkled filter element or a group of wrinkled filter elements. This method can also be particularly useful for determining or evaluating the distribution of porosity within a wrinkled and clustered tobacco plug or group of such plugs. This method can be particularly useful for determining the proportion of loose ends in a conventional cigarette or group of cigarettes.

Therefore, the method may be a method for evaluating the porosity distribution in a continuous rod member formed of a cluster sheet, such as a tobacco plug member formed of or containing a cluster tobacco sheet, or a non- Filter element or element made of tobacco material. The continuous member may include a member selected from a bag Includes metal foil, polymer flakes, and sheets of groups of substantially non-perforated paper or cardboard. The continuous rod may include a member selected from polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), and Sheets made of aluminum foil. The continuous rod may include non-porous paper or a biodegradable polymer, such as a sheet of polylactic acid or Mater-Bi® grade (commercially available starch-based copolyester family).

The cross-sectional area of the continuous rod is the cross-section or end face of the continuous rod. The method includes: obtaining a digital image of a cross-sectional area of the continuous rod; determining a hole area ratio in each of a plurality of sub-regions of the same size in the cross-sectional area, thereby obtaining a plurality of hole area ratios; and calculating a complex number The standard deviation of the pore area ratio is used to evaluate the porosity distribution in the cross-sectional area of the porous article, wherein each sub-region overlaps with at least one adjacent sub-region between 10% and 95%.

A second aspect of the present invention can provide a method for controlling the manufacturing process of porous articles such as porous rods, including the steps of: performing a process to produce at least one porous article; and using any of the methods described above to evaluate the content of at least one porous article. The porosity distribution; and using the porosity distribution to control more than one process parameter of a process for manufacturing further porous articles. For example, the porosity distribution of the at least one porous article may be used to determine whether to change one or more process parameters of a process for manufacturing further porous articles. It may be preferable to evaluate the porosity of more than one porous article simultaneously. It may be advantageous to assess the assessment of porosity within a porous article on a regular or continuous basis to provide constant feedback to the porous article production method.

The present invention can provide a method for controlling the porosity of a porous article such as a porous rod, which comprises using a porous article manufacturing method to form a porous article, and using any of the methods described above to evaluate A step of controlling the porosity distribution and controlling one or more process parameters of the porous article process to form a further porous article having a desired porosity distribution.

The process of making porous articles can be a process of wrinkling and bunching filter elements. The porous articles are rods of filter material. For example, the rod process may include the steps of feeding the sheet through a creping roll and then bundling the crumpled sheet into a bundled continuous rod. Bundle continuous rods can be wrapped with packaging materials to produce continuous filter rods. Then, the continuous filter rod can be split to produce individual filter member rods. In a method of controlling the process, the individual filter elements produced can be selected periodically, and the porosity distribution of the selected rods can be evaluated according to any of the above methods. The cross-sectional area of the imaging member used for evaluation may be one section or the other end of the filter member perpendicular to the longitudinal direction of the filter member.

The evaluation results of the porosity distribution in the filter element can indicate the quality of the filter rod produced by the manufacturing process. If the evaluated porosity deviates from the ideal level, the process parameters can be changed to change the porosity distribution. For example, the distance between the creping rolls may be changed, or the speed at which the sheet is fed into the bundling means may be changed. By providing feedback, a more consistent filter element with a uniform porosity distribution and the desired properties can be produced.

The porous article process can be a tobacco stopper process, and therefore, the porous article can be a tobacco rod. The formation of the tobacco rod or plug may be similar to that used to produce filter material above. For example, for the production of tobacco rods, a homogeneous sheet can be fed via a creping roll and bundled into a continuous Pole. The continuous rod can be wrapped with packaging material and then sliced to form individual tobacco rods or tobacco plugs. It may be particularly advantageous that the uniformity of tobacco plugs so produced can be monitored in accordance with the present invention, and the uniformity monitoring of porosity provides feedback to the process to modify more than one process parameter of the process, thereby improving the tobacco plugs so formed Quality.

The porous article process may be a cigarette process, and the porous article may be a standard conventional cigarette. By monitoring the porosity of the ends of selected cigarettes, the process parameters can be controlled to result in a lower ratio of loose ends to the ends of the cigarettes. This can improve the quality of the products produced.

The above method can be used to produce porous articles having predetermined properties. For example, certain properties of the article may be desirable, and methods of assessing the porosity distribution may be used to provide feedback so that users can control processing parameters and produce articles with the desired properties.

For example, it may be desirable to form a rod with longitudinally open holes, and it may be desirable for the rod to provide some predetermined filtering efficiency. By evaluating the porosity distribution of the rod when producing the rod, the process parameters can be controlled to obtain a predetermined filtration efficiency.

As a further example, when an article is formed from a tobacco material, such as a rod formed from more than one recycled tobacco sheet, it may be desirable to specify the porosity of the article to provide a predetermined amount of nicotine delivery during the use of the article. By evaluating the porosity distribution of the tobacco article when it is produced, the process parameters can be controlled to obtain a predetermined nicotine delivery.

As a further example, when the article is a conventional cigarette made of cut-leaf tobacco, the porosity distribution at the end of the cigarette can be evaluated and this information can be fed back to control process parameters and reduce the proportion of loose ends.

The method of controlling a porous article process or the method of controlling the porosity of a porous article may include a step of comparing the evaluated porosity distribution with a reference porosity distribution and controlling more than one process parameter in response to the comparison.

When the porous article is a member formed of a bundled sheet, the method may include using a camera installed on a production line forming the member to obtain a digital image of a cross-sectional area of the member, the cross-sectional area being a member of the member. The end face makes it possible to immediately evaluate the porosity distribution of the rod during manufacturing. Alternatively, after the rod is manufactured, an offline device may be used to evaluate the porosity distribution of the rod. The offline device includes digital image acquisition means and a processing unit for evaluating the porosity distribution of the rod. A batch of rods can be fed into this device to evaluate the porosity distribution of the rods or the entire batch.

A device for evaluating the porosity distribution can be provided. This device evaluates the porosity distribution according to any of the methods described above. The device may include means for capturing a digital image of a cross-sectional area of the article and a processor for analyzing the digital image and calculating a porosity distribution. The means for capturing digital images is preferably a digital camera.

This device may include a light source for illuminating a cross-sectional area of the article. For example, the light source may be a spotlight or a flash unit. Preferably, the light source provides uniform irradiation of the porous article. The preferred light source may be a ring lamp or a ring flash lamp arranged near the lens of the camera or at a predetermined distance from the porous article to provide uniform illumination of the article.

The device may include: a sensor for determining the position of the porous article; and a triggering means for detecting the position of the porous article. Or capture a digital image while passing through a predetermined position. For example, a digital image may be obtained while a porous article is being formed or a product including a porous article is being assembled. When the porous object is properly positioned, the sensor can trigger image capture.

The device can be installed inline on a production line forming porous articles to assess the porous distribution of the articles in real time. Alternatively, the device may be a stand-alone device.

Porous rods such as tobacco stoppers and filters for smoking articles are made into continuous rods at high speed. This continuous rod is a tubular article that can be cut into smaller rod-like articles at certain points. For example, a porous article including a tobacco cluster sheet for a smoking article is first made into a long rod-like article, which in many steps is cut to the final rod length to be filled into the smoking article. Rod-shaped articles in a production line are usually transferred by drums or rolling elements.

The rod-shaped porous article can be produced using, for example, a commercially available rod-making machine. Tubular continuous articles can be cut into regular sections initially, each section having a size larger than one final rod-shaped article, for example, a long rod includes 10 lengths of the final rod-shaped article, followed by more than one cutting step, and the final Rod-shaped items. At the output end of this rod-making device, the rod can pass through the rolling element before being deposited on the flat elbow. A digital image of the cross-section of the member can be taken when the member is output to a flat elbow. The cross section is the end face of the rod.

The linear speed of the rod making machine can be 100 m / min or more. For example, the linear speed of the rod making machine can be 150 m / min or 200 m / min. Digital images of the cross-section of one or more members can be obtained using a digital camera. Preferably a high speed camera is used. In a specific embodiment, suitable When the camera can be a new force XCD-V60 with 8 relative shutters and the HF25SA with the objective lens opened with a 2 + 5 mm extension. Other cameras can also be used, such as the Sony XCD-SX90 with HF25 objective or HF35HA-1B objective. For porous members with a diameter of about 7.5 mm, the resolution of the camera should be high enough to ensure that the image of the cross section of each porous member is represented by at least about 500 × 500 pixels.

In one embodiment, the camera is positioned horizontally to capture the end face of the rod passing between the rolling element and the elbow of the rod making machine. When the lever is accurately placed in the rolling element, a constant distance between the end face of the lever and the camera is obtained. The sensor can be used to control the shutter of the camera to obtain a digital image of the cross-section of the lever when the lever is optimally positioned in front of the camera's lens and when the exposed face is exposed. Alternatively, the shutter of the camera may be triggered by a scrolling element.

Alternatively, the device can automatically position the bar in the correct position to capture digital images. For a porous member with a diameter of about 7.5 mm, the position accuracy should be at least ± 0.2 mm.

Illumination of the end face of the rod can be achieved by using a spotlight, such as a Schott spotlight set at an angle of 45 °. Alternatively, a stronger light source such as Volpi IntraLED 3 may be used.

You can also take a digital image of the end face of the rod on the synthesizer before the final product is assembled. For example, if a rod-shaped filter or a tobacco plug is filled with a smoking article, an image of an end surface of the rod-shaped filter or the tobacco plug can be obtained during the assembly of the smoking article. After being assembled into the final product, for example, when the cross-section of the porous member is exposed, an image of the porous member is obtained. To control the quality of tobacco products such as tobacco rods and filters, Obtaining more than one digital image, such as imaging one end face of a tobacco plug, and imaging the other end face of a filter.

Certain porous materials such as, for example, filter elements may have reflective cross-sectional surfaces. In order to obtain a high-quality digital image of the cross-section of such an article, uniform light is needed near the location where the cross-section is exposed. Lighting can be achieved through white light, such as the white light source LED SCHOTT LSS A20960. Lighting can be set to different illuminance depending on the material forming the porous rod. For example, when capturing digital images of tobacco rods, the illuminance can be set to 100%, or 30% in the case of filter material. Lighting can also be achieved with a ring light, such as, for example, a ring light A08660 (Schott). The distance between the light source and the porous member is optimized according to the light source and the material of the member. Those skilled in the art should know that the light source and optical power may have to be modified according to the material of the porous article.

The porosity distribution within the porous member can be calculated using a processor, for example, by using a PC.

By adjusting certain process parameters, such as, for example, wrinkling of the input material, feedback to a manufacturing device or production line for porous articles can be facilitated. For example, the polylactic acid-containing filter may include wrinkling and bundling sheets, and feedback may change the degree of wrinkling of the sheet prior to bundling. It can also feedback to automatically reject or withdraw porous items with a porous distribution that does not meet the predetermined specifications. On the assembly line, processor feedback can be used to reject the final product.

The device preferably has a user interface such as, for example, a keyboard, a bar code reader or a touch screen or other means of communicating with an external data processing or programming device.

10‧‧‧Tobacco rod

20‧‧‧ Tobacco

30‧‧‧ Rod

40‧‧‧plug

100‧‧‧ the first subregion

200‧‧‧ second subregion

300‧‧‧ third subregion

400‧‧‧ Fourth subregion

500‧‧‧ fifth subregion

910‧‧‧ Camera

911‧‧‧ camera lens

920‧‧‧Tobacco rod

921‧‧‧face

930‧‧‧Ring light

1000‧‧‧ device or system

1010‧‧‧ Digital Camera

1011‧‧‧Lens

1020‧‧‧light source

1021‧‧‧Ring light

1030‧‧‧Sensor

1040‧‧‧PC

1050‧‧‧ Controller

1060‧‧‧Monitor

A specific embodiment of the present invention will now be described with reference to the drawings, wherein FIG. 1 is an image of a cross-sectional area of a porous tobacco rod. The image shows overlapping child regions.

Fig. 2 is a cross-sectional area of the tobacco rod shown in Fig. 1, which shows sub-areas in different parts of the cross-sectional area.

Figure 3 shows the cross-sectional area of Figure 1 and the sub-areas in a third different part of the cross-sectional area.

Figure 4 shows the extent to which the sub-region of Figure 3 overlaps with another sub-region.

Figure 5 shows the extent to which another sub-region overlaps with the sub-region of Figure 4.

Figure 6 shows the cross-sectional area of Figure 1 and shows the sub-area positioned so that most of the sub-areas are not within the cross-sectional area.

Figure 7 is a graph showing the distribution of overall porosity in a group of tobacco stoppers.

Figure 8 is a graph showing the local porosity distribution for a group of tobacco stoppers.

Figure 9 is a schematic diagram of an image acquisition method used for online porosity distribution evaluation.

Figure 10 is a schematic diagram showing the components of a device for performing an online porosity distribution evaluation.

A specific embodiment of the present invention will now be described with reference to a method for evaluating the porosity distribution in a tobacco stopper.

FIG. 1 shows the formation of the end face of the tobacco rod 10 by a process of wrinkling and bundling a homogeneous tobacco sheet. The image coefficient image of FIG. 1 has been processed so that all the white pixels correspond to the tobacco 20, the black pixels on the outer periphery of the rod member 30 are related to the background, and the black pixels on the circumference of the plug member 40 correspond to the holes. By taking an image of the end face of the tobacco plug and digitally processing the pixels in the cross-sectional area of the plug to identify the pixels in the cross-sectional area of the rod, an image is obtained. The threshold is then applied to the image so that the pixels in the cross-sectional area are white representing tobacco material or black representing holes. In Fig. 1, the tobacco stopper is substantially circular and has a diameter of about 7 mm. The entire area within the outer periphery of the tobacco stopper is a cross-sectional area. FIG. 1 shows a first sub-region 100 positioned within a cross-sectional area. The first sub-region is a rectangular region of 1 mm by 1 mm size.

As shown in FIG. 1, the first sub-region 100 is located at a position where the local porosity is low. In other words, the hole area (black pixels in the first sub-region 100 in FIG. 1) is smaller than the total area of the first sub-region (1 square millimeter).

Figure 2 shows the same cross-sectional area as shown in Figure 1. Figure 2 shows a second sub-region 200, which is positioned in a region with higher local porosity, as reflected in the region of higher porosity within the corresponding sub-region. Different sub-regions located in different regions of the cross-sectional region have different hole area ratios. By evaluating the pore area ratio of multiple sub-regions within the cross-sectional region, a porosity distribution can be obtained.

By calculating the local porosity (i.e., pore area ratio) of each of the plurality of sub-regions, a porosity distribution is obtained. For each individual tobacco sub-region, the pore area ratio of the sub-region of the image is calculated, which can be called local porosity. The local porosity can be calculated by the following formula P ₁ = N _voidlocal / N _local , where P ₁ is the local porosity in the subregion, N _voidlocal is the number of pixels in the void space in the subregion, and N _local is the pixels in the subregion. total. The subarea is applied to and translated into the digital image of the rod through an iterative algorithm incorporated into the software. In order to obtain the plurality of local porosity readings, the sub-regions are effectively transformed sequentially through the image, and the local porosity of each position occupied by the sub-regions is calculated. Each position occupied by the sub-region overlaps with at least one other position occupied by the sub-region. This procedure is shown in Figures 3 to 5.

Figure 3 shows a cross-sectional area of a tobacco stopper with a third sub-region 300 overlapping the left side of the stopper. Calculate the local porosity in this subregion. This sub-region is then translated across the cross-sectional region to the right. Figure 4 shows a fourth sub-region 400 superimposed on a digital image of a tobacco stopper. Figure 4 also shows (dotted line) the position of the third sub-region 300. It can be seen that the positions of the fourth sub-region 400 and the third sub-region 300 overlap. The local porosity in the fourth sub-region is calculated, and the sub-region is once again translated across the cross-sectional region. FIG. 5 shows a cross-sectional area, which shows a fifth sub-region 500. FIG. 5 also shows (dotted lines) the positions of the third sub-region 300 and the fourth sub-region 400. The local porosity of the fifth sub-region 500 is obtained, and the sub-region is once again translated through the structure. This proceeds until all pixels in the structure have been contained in more than one sub-region.

In the example here, if at least 90% of the pixels in the sub-region are also in the cross-sectional region, only the local porosity in the sub-region is calculated. Preferably, at least 50% of the pixels in the sub-region are also in the cross-sectional region. First Figure 6 shows a cross-sectional area of the tobacco stopper and a sixth sub-area 600 superimposed on the digital image. Less than 90% of the pixels of the sixth sub-region 600 are in the cross-sectional area, that is, the area inside the tobacco stopper. Therefore, local porosity is not calculated for this sixth subregion. This is to avoid calculating local porosity for sub-regions that are not high enough to represent the local porosity area of the local tobacco structure.

The calculated local porosity of each sub-region is stored in an array. The mean and standard deviation of local porosity can be calculated for the tobacco plug. The standard deviation of local porosity can be used as a measure of the width of the porosity distribution. This provides a quantitative value of how the tobacco is evenly distributed in the plug. A low standard deviation indicates a uniform plug, while a high standard deviation indicates a non-uniform plug.

This method can be used to calculate the porosity distribution of a plurality of tobacco plugs simultaneously. For example, a digital image showing a cross-sectional area of a plurality of tobacco plugs can be obtained, and the digital images can be processed to identify each individual tobacco plug, and obtain a porous distribution from each individual tobacco plug in the manner described above. Then, a porosity distribution can be obtained for each individual tobacco stopper or for a plurality of tobacco stoppers. As an example, a plurality of tobacco stoppers may be placed on a flatbed scanner and scanned to produce a digital image showing the end face of each of the plurality of tobacco stoppers. It should be noted that the acquisition of digital images can be accomplished by any suitable method, such as by using a digital camera or computer tomography. The image can be represented by any suitable image format, in full RGB (red-green-blue) color, grayscale, or binary (black and white) display. Preferably, the background of any image is uniform, which facilitates the detection and removal of the background during image processing. The resolution of any image should be high enough to accurately analyze the shape of the tobacco plug.

After capturing the images, if they are color images, they can be converted to grayscale, and the contrast can be adjusted to increase the difference between the tobacco area and the hole area.

If the image is not binary yet, convert it to binary. In a preferred embodiment, negative images of images of a plurality of tobacco plugs are obtained, where black pixels represent solids and white pixels represent holes or void spaces, which facilitates automatic detection of tobacco plugs in the image. The negative black areas in the negative image that correspond to the solid material in the tobacco stopper are identified and labeled with numbers and stored in the list. In one embodiment, for each labeled connected black area, the smallest possible rectangular border area is calculated. Calculate the area and aspect ratio of each rectangular border area, and remove the connected black areas with high or low aspect ratio from the list in the rectangular border area. Since the tobacco stopper is substantially circular, each rectangular border area surrounding the tobacco stopper should have an aspect ratio of about 1: 1. Then, sort by decreasing size and select all detected black areas so that the area representing the tobacco stopper should reach or approach the beginning of the list. In addition, the connecting black areas in the rectangular border area having an area substantially higher or lower than the area expected for the tested article, that is, the tobacco stopper, may be removed from the connecting black area list. In certain preferred embodiments, the connecting black areas are removed in a border area having a larger or smaller area than 50% of the expected area of the rectangular border area, or more preferably larger or smaller than 30% of the expected area of the rectangular border area. The area of the detected black area can also be used instead of the border area. In alternative embodiments, the boundary regions may be in different shapes, such as circles; polygons such as octagons, triangles, squares, rhombuses; or combinations thereof.

To confirm which areas on the list correspond to tobacco plugs, the size of the area can optionally be checked over the range of the expected number of plugs. For example, if the expected number of plugs in the image is represented by the letter n, the size changes of areas 1 to n in the list can be calculated and stored as an array. Since the plug region need not be the largest black region in the negative image, the size change calculation is performed for the regions 2 to n + 1, 3 to n + 2, and so on. This continues until all connected black areas remaining in the list have been measured. To determine where the first plug region appears in the list, identify the minimum value of the calculated change. Next, the areas corresponding to other tobacco plugs should be recognizable, since the plugs should be almost the same size.

Individual plugs in a set of plug images can be found by other means. A plurality of plugs constituting a group of plugs can each have their own digital images, which negates the need to extract images of individual plugs.

A binary shielding function may be used, where the tobacco stopper has a value of 1, or in other words, where the cross-sectional area and the area surrounding the tobacco stopper have a value of 0.

Porosity calculations can then be performed on each cross-sectional area. Using threshold values, the cross-sectional area of each tobacco stopper is converted into a binary image. In binary images, black pixels represent void space and white pixels represent tobacco material. According to the equation: P _o = N _void / N _tot , calculate the overall porosity from the area ratio, where P _o is the overall porosity of the cross-sectional area, N _void is the number of pixels in the void space in the cross-sectional area, and N _tot is The total number of pixels in the cross-sectional area. For a set of tobacco plugs, the overall porosity derived from each plug can be plotted on a chart similar to that shown in Figure 7. Figure 7 shows a group of tobacco stoppers having an overall porosity with a narrow distribution between 0.2 and 0.4.

The porosity distribution can be calculated for each tobacco stopper in the group according to the method described above with respect to Figures 1 to 6. In addition to providing a porosity distribution for each individual plug, the overall porosity distribution of the group of plugs can be determined as shown in the graph in Figure 8. The cumulative porosity distribution of different sets of tobacco plugs can be compared to each other to provide an indication of quality differences between different batches.

As explained above with respect to individual porous members or a group of porous members, the results of the porosity evaluation can be used to control the process of the porous member. Therefore, the method of assessing porosity can provide feedback on when to set processing parameters to produce porous rods that meet specifications, and allow calibration of process parameters to generate feedback that produces porous rods within acceptable specifications.

A device for evaluating the porosity distribution of a porous article such as a tobacco plug member formed of a tobacco cluster sheet or a filter member formed of a cluster sheet of polylactic acid can be integrated as part of the manufacture of porous articles. An apparatus for assessing the distribution of porosity requires image acquisition means such as a digital camera and a processor for performing the necessary processing steps for analyzing digital images obtained from porous objects. The device preferably further comprises a light source for illuminating the porous article.

FIG. 9 shows the configuration of the image capturing means, in which a camera 910 is configured to capture a digital image of the end surface 921 of the tobacco rod 920. The tobacco rod 920 is formed by wrinkling and bundling a homogeneous tobacco sheet, and wrapping the bundling sheet with a packaging material to produce the rod. The lens 911 of the camera 910 is set at a predetermined distance from the end surface 921 of the tobacco rod 920.

To provide uniform illumination of the end surface 921 of the tobacco rod 920, a ring light 930, such as a SCHOTT ring light A08660, is disposed between the camera lens 911 and the tobacco rod 920. The ring light 930 is preferably positioned closer to the tobacco rod 920 than the camera lens 911.

Figure 10 shows a device or system 1000 for evaluating the porosity distribution of a porous rod, such as a tobacco rod. The device or system 1000 includes a digital camera 1010 having a lens 1011, and a light source 1020 coupled to a ring lamp 1021. The shutter of the camera is controlled by a sensor 1030 that can detect the position of the porous member. The processing of the digital images obtained by the camera 1010 is executed by the processor within the PC 1040. The sensor, light source, camera and PC are linked together by the controller 1050. The PC includes a keyboard 1050 and a monitor 1060. The system or device with the components shown in Figure 10 can be incorporated into a rod manufacturing facility to instantly evaluate the porosity distribution in the rod as it is formed. The system or device 1000 may be incorporated into a cigarette or smoking article assembly line and evaluates the porosity distribution of the components of the cigarette or smoking article when assembling the cigarette or smoking article. Alternatively, the system or device having the components of FIG. 10 may form part of an independent evaluation device for offline evaluation of the porosity distribution of a batch of porous rods.

Claims (28)

A method for evaluating the porosity distribution in a porous article, the method comprising the steps of: obtaining a digital image of a cross-sectional area of the article; determining a pore area in each of a plurality of sub-areas of the same size in the cross-sectional area Ratio, thereby obtaining a plurality of pore area ratios; and using the plurality of pore area ratios to evaluate a porosity distribution in the cross-sectional area of the porous article; wherein each sub-region overlaps at least one adjacent sub-region Between 10% and 95%. The method of claim 1, wherein the standard deviation of the plurality of pore area ratios is calculated, and the width of the porosity distribution is expressed by the standard deviation of the plurality of pore area ratios. The method of claim 1 or 2, wherein the digital image of the cross-sectional area is composed of a plurality of pixels, and each pixel constituting the cross-sectional area is included in at least one of the plurality of sub-regions. The method of claim 3, wherein the digital image of the cross-sectional area is at least 500 × 500 pixels. The method of claim 1, wherein each sub-region overlaps with at least one adjacent sub-region between 70% and 90%. For example, the method of claim 1, wherein if more than 50% of the sub-regions are within the cross-sectional area of the article, only the area ratio of any individual sub-regions is used to evaluate the porosity distribution. The method of claim 1, comprising: determining the total area ratio of the holes in the cross-sectional area of the article. The method of claim 1, wherein the digital image is obtained from each of a plurality of articles, the plurality of articles forming a group of articles, and the porosity distribution is evaluated for the entire group of articles. The method of claim 8, wherein a digital image including an image of a cross-sectional area of the plurality of items is obtained, the method including detecting the image of the individual item and masking the image to exclude a cross-section that does not belong to any of the plurality of items Steps within a region of pixels. The method of claim 1, wherein the porous article is in the form of a plurality of open holes extending longitudinally by a rod. The method of claim 1, wherein the porous article is a continuous rod formed of a cluster sheet, and a cross-sectional area of the article is a cross-section or an end surface of the continuous rod. A method for controlling the process of a porous article, comprising the steps of: performing a process to produce at least one porous article; using the method of any one of the above claims 1 to 11 to evaluate the porosity distribution within the at least one porous article; and The porosity distribution is used to control more than one process parameter of the porous article process. A method for controlling the porosity of a porous article, comprising the steps of: forming a porous article using a process of the porous article; and evaluating the porosity in the porous article using a method as claimed in any one of claims 1 to 11. Distribution; and controlling one or more process parameters of the process of the porous article to form a further porous article, the further porous article having a desired porosity distribution. The method of claim 12 or 13, wherein the process of manufacturing the porous article is a cigarette manufacturing process, and the porous article is a cigarette. The method according to claim 12 or 13, wherein the process of manufacturing the porous article is a process of manufacturing a filter element, and the porous article is a rod of filter material. The method according to claim 15, wherein the porous article is a filter member formed of a cluster sheet. The method of claim 12 or 13, wherein the process of manufacturing the porous article is a tobacco stopper process, and the porous article is a tobacco stopper. The method of claim 17, wherein the tobacco stopper is formed of a cluster sheet. The method of claim 12 or 13, including the step of comparing the evaluated porosity distribution with a reference porosity distribution and controlling more than one process parameter in response to the comparison. The method of claim 12 or 13, wherein the porous article is a rod formed of a bundle sheet, the method includes the step of obtaining a digital image of a cross-sectional area of the rod, the cross-sectional area being an end surface of the rod, and The use of a camera mounted on the production line used to form the rod allows the porosity distribution of the rod to be evaluated immediately during manufacture. The method of claim 12 or 13, wherein the porous article is a rod formed of a cluster sheet, wherein an offline device is used, and after the rod is manufactured, an evaluation of the porosity distribution of the rod is performed, the offline device includes a digital Image acquisition means and processing unit for evaluating the porosity distribution of the rod. The method of claim 12 or 13 is used for producing a porous article having a predetermined filtration efficiency. The method of claim 12 or 13, which is used in the production of tobacco products or tobacco stoppers for tobacco products, wherein the local porosity distribution is controlled during the use of the tobacco product to provide a predetermined nicotine output. The method of claim 14 wherein the process parameters are controlled to produce cigarettes with a lower proportion of loose ends. A device for evaluating a porosity distribution in a porous article using a method as claimed in any one of claims 1 to 11, the device comprising means for capturing a digital image of a cross-sectional area of the article and analyzing the digital A processor that images and calculates the porosity distribution. The device of claim 25 including a light source to illuminate the cross-sectional area of the article. For example, the device of claim 25 or 26 includes a sensor to determine the position of the porous article, and triggers a means for capturing digital images when the porous article is at or through a predetermined position. If the device of item 25 or 26 is requested, it is used for inline installation on the production line to evaluate the porosity distribution of the item in real time.