System and method for analyzing tablet coatings

Abstract

A system (1) for analyzing the coating of tablets, pills, capsules and the like for pharmaceutical and / or food applications, which may be associated with a tablet coater machine (50), comprises an exit chute (51) configured to be associated with the coater machine (50), a dome illuminator (2) arranged to illuminate a detection zone (B) of a descent plane (52) of the exit chute (51) along which the tablets (100, 101) fall by gravity, a vision means (3) associated with the dome illuminator (2) and arranged to detect images of the tablets (100, 101) moving on the descent plane (52), and a control unit (10) connected to the vision means (3) to receive images of the tablets (100, 101), configured to track the movement of each tablet (100, 101), analyze only images of selected tablets without shadows, in particular single, spaced apart tablets with their maximum extension surface exposed to the vision means (3), and assess the color uniformity of the outer surfaces of the selected tablets.

Description

[Technical Field]

[0001] The present invention relates to machines and methods for coating tablets, pills and capsules for pharmaceutical and food applications, and in particular to a system that can be associated with a tablet coating machine for automatically analyzing the quality of a coating applied to tablets. The invention further relates to a method for analyzing the coating of tablets in a tablet coating machine. [Background Art]

[0002] In the pharmaceutical and food industries, it is known to use machines and processes for applying a coating to the outer surface of tablets, pills, capsules and the like, for example, to protect tablets, pills, capsules and the like from gastric acid, to protect the gastric mucosa from aggressive agents contained in the tablets, to enable delayed release of the active agent by adjusting the dissolution rate of the tablets, or to maintain the shape of the tablets or pills.

[0003] Known coating machines generally comprise a rotating drum in which a controlled atmosphere is maintained and into which tablets to be processed are introduced. Inside the rotating drum, there is a dispenser such as a sprayer or nebulizer that discharges a substance, generally a liquid substance, that adheres to the outer surface of the tablets and dries to form a coating. The rotating drum is equipped with angular blades or baffles, so that the tablets move and mix during rotation about the horizontal axis of the rotating drum, specifically being lifted and rotated toward the center of the rotating drum, so that the tablets gradually and uniformly receive the coating substance discharged by the sprayer, and an air flow passes transversely through the rotating drum.

[0004] The coating applied to the outer surface of each tablet is dried by introducing hot air into the rotating drum and regulating both the flow and temperature of the hot air so that the drying process is performed in a controlled manner.

[0005] A so-called batch coating system is known, which involves introducing a specific amount of tablets (batch) into the rotating drum of a coating machine, followed by removing a specific amount of tablets after the coating process is completed.

[0006] Furthermore, a so-called continuous flow coating system is also known, in which tablets at a constant (mass) flow rate are introduced to the first end of the rotating drum of a coater machine, pass longitudinally through the rotating drum while it is rotating, and after being coated, are continuously removed from the second end of the drum on the opposite side. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] REKalman. “A New Approach to Linear Filtering and Prediction Problems”. Journal of Basic Engineering, 1960, 82.1: 35-45 [Non-Patent Document 2] P. Jaccard. "The distribution of the flora in the alpine zone." New Phytologist, 1912, 11.2:37-50) and the Hungarian algorithm (HW Kuhn. "The Hungarian method for the assignment problem." Naval Research Logistics Quarterly, 1955, 2.1-2:83-97) [Non-Patent Document 3] J. O'Rourke. “Finding minimal enclosing boxes”. International journal of computer & information sciences, 1985, 14.3: 183-199 [Non-Patent Document 4] J. Canny. “A Computational Approach To Edge Detection”, IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986, 8.6: 679-698 [Non-Patent Document 5] “Improvement to industrial color-difference evaluation”, Wien:CIE Publication No.142-2001, Central Bureau of the CIE;2001 [Overview of the project]

[0008] In both types of coating systems, it is known that it is necessary to check the quality of the coating in order to optimally adjust process parameters such as the average residence time of the tablets in the rotating drum, the amount of coating material dispensed per unit time, and the rotation speed of the rotating drum.

[0009] Coating analysis is a known method that allows for the periodic collection of samples of coated tablets by analyzing the color of the outer surface using specialized measuring instruments such as colorimeters, spectrophotometers, and spectrophotometers. By measuring the difference between the detected color and the color of a reference standard tablet, an indicator of coating quality can be obtained.

[0010] Furthermore, a system is used to evaluate the quality of the coating based on changes in the weight of tablet samples.

[0011] However, these analytical systems are cumbersome because they require manual removal of tablet samples from a rotating drum, and they can only analyze a very small number of coated tablets, resulting in very low statistical quality control during manufacturing.

[0012] One object of the present invention is to improve known systems for analyzing the coating of tablets associated with coater machines, particularly continuous flow coater machines for tablets, pills, capsules, etc.

[0013] Another objective is to provide a simple and inexpensive system that allows for the automatic analysis of a large number of tablets removed from a continuous flow coater without operator intervention.

[0014] A further objective is to develop a system that enables accurate and precise evaluation of coating quality, particularly the internal and external variability index of the coating on tablets processed by a coating machine.

[0015] In a first aspect of the present invention, a system for analyzing the coating of a tablet as described in claim 1 is provided.

[0016] A second aspect of the present invention provides a method for analyzing the coating of a tablet as described in claim 7. [Brief explanation of the drawing]

[0017] The present invention can be better understood and implemented by referring to the accompanying drawings illustrating exemplary and non-limiting embodiments of the invention.

[0018] [Figure 1] This is a schematic partial cross-sectional front view of a tablet coating machine associated with a system for analyzing the coating of tablets according to the present invention. [Figure 2] This is a cross-sectional view along line II-II in Figure 1 illustrating the system of the present invention, particularly in relation to the tablet exit chute. [Figure 3] This is a cross-sectional view of the dome illuminator and visual means of the system of the present invention. [Figure 4]It is a partially enlarged view of an outlet chute for tablets, showing a plurality of tablets of various shapes placed in various positions. [Figure 5] Figures 5a and 5b show two elongated tablets respectively having a low internal variation index and a high internal variation index. [Figure 6] Figures 6a and 6b show groups of elongated tablets respectively having a low external variation index and a high external variation index. MODE FOR CARRYING OUT THE INVENTION

[0019] Referring to Figures 1 to 4, the system 1 of the present invention for analyzing coatings of pharmaceutical and / or food products such as tablets, pills, capsules associated with a tablet coater 50 will be schematically described.

[0020] The coater 50 is, for example, a known type of continuous flow machine including a rotating drum 55 that is elongated and rotatable about a rotation axis X, particularly a horizontal rotation axis X. The rotating drum 55 is provided at a first end 55a with a first unshown opening for feeding tablets 100 to be coated, and is provided at the opposite second end 55b with a second opening connected to an outlet chute 51 of the system 1 of the present invention for coated tablets.

[0021] Inside the rotating drum 55, there is a discharge means 56 arranged to discharge a substance for forming a coating by adhering to the outer surface of the tablets 100, for example a liquid substance. The discharge means 56 comprises, for example, a plurality of sprayers 57 fixed to a supply duct 58 for supplying the coating substance.

[0022] In addition to the outlet chute 51, the system 1 for analyzing tablet coating comprises a dome illuminator 2 arranged to illuminate a detection zone B on a descending plane 52 of the outlet chute 51 where tablets 100 descend by gravity along the outlet direction A.

[0023] The system further comprises a visual means 3 associated with a dome illuminator 2 and positioned to detect images of tablets 100 in detection zone B, and a control unit 10 connected to the visual means 3 to receive images of tablets 100. The control unit 10 is configured to track the movement of each tablet 100 and analyze only images of selected tablets without shading, particularly single, separated tablets whose maximum extended surface is exposed to the visual means 3, in order to evaluate the uniformity of the color of the outer surface of the selected tablets.

[0024] In particular, the control unit 10 implements a tracking algorithm that provides the following procedures.

[0025] Considering the q-th image of the tablets moving along the exit chute, acquired by the visual system 3, first, each tablet 100 present in the image is identified. Subsequently, based on physical considerations and the use of a Kalman filter (REKalman. "A New Approach to Linear Filtering and Prediction Problems". Journal of Basic Engineering, 1960, 82.1:35-45), the position of the tablets in the (q+1)-th image is predicted based on the position of the tablets in the q-th image. Finally, after identifying each tablet 100 present in the (q+1)th image acquired by the visual means 3, the concept of Jaccard distance (P. Jaccard. "The distribution of the flora in the alpine zone". New phytologist, 1912, 11.2:37-50) and the Hungarian algorithm (HW Kuhn. "The Hungarian method for the assignment problem". Naval Research Logistics Quarterly, 1955, 2.1-2:83-97) are used to associate the new position of each tablet 100 in the (q+1)th image with its prediction derived from the analysis of the qth image.

[0026] The control unit 10 tracks the movement of each tablet, distinguishing tablets within each image acquired by the visual system 3, and can analyze tablets separately if they do not have shading. In other words, referring particularly to Figure 4, the control unit 10 is configured to discard and not evaluate the uniformity of the outer surface color of tablets that have shading or shading zones C, i.e., areas of the outer surface that are not properly and completely illuminated by the light emitted by the dome illuminator 2 because, for example, tablets are overlapping, touching, or tilted.

[0027] More precisely, three criteria are used to evaluate whether tablets 100 and 101 are adequately and completely illuminated by the light emitted by the dome illuminator 2, have no shaded zones, and are therefore suitable for color uniformity analysis. These three criteria may be used individually or in combination. For example, one can choose to analyze a tablet only if all three criteria are met, or to analyze it if at least one of the criteria is met.

[0028] The first criterion is based on an evaluation of the aspect ratio of the tablet under consideration, which is defined as the ratio of the length to the width of the relative oriented closing rectangle (J. O'Rourke. "Finding minimal enclosing boxes". International journal of computer & information sciences, 1985, 14.3:183-199). In particular, the tablet color is analyzed if the aspect ratio does not deviate excessively from the value obtained by achieving the ratio between the theoretical actual dimensions corresponding to the type of tablet under consideration (round or circular 100 or elongated 101) (the operator can set an acceptable threshold).

[0029] The second criterion specifies that the operator instead provides the control unit 10 with a model image (template) of the type of tablet under consideration (round or circular 100 or elongated 101) taken in an ideal pose, whose outer contour is identified by the Canny algorithm (J. Canny. "A Computational Approach To Edge Detection", IEEE Transactions on Pattern Analysis and Machine Intelligence, 1986, 8.6:679-698). Subsequently, the outer contour of the tablet is also detected, the analyzability of the tablet's color is evaluated, and the anisocoria with respect to the outer contour of the model tablet is calculated. If this index falls below the tolerance threshold specified by the operator, the color of the tablet under consideration is analyzed.

[0030] The third criterion is based on the identification of edges present within the image of the tablet, which needs to be evaluated for color analysis. These edges are also identified using the Canny algorithm described above. In particular, if the number of pixels belonging to these edges is less than the tolerance threshold specified by the operator, the tablet's color is analyzed.

[0031] In Figure 4, as an example, shaded tablets are grouped together and indicated by the reference symbol R, and include round or circular tablets 100 and elongated tablets 101. In this way, the control unit 10 actually selects and evaluates only the color uniformity of single, separated tablets whose maximum extending surface is exposed to the viewing means 3, i.e., tablets whose opposite maximum extending surface is in contact with the descent plane 52. In Figure 4, these selected tablets are grouped together and indicated by the reference symbol S, and include round or circular tablets 100 and oval tablets 101. In this way, the viewing means 3 can optimally detect a complete and illuminated image of the outer surface of the tablets 100 to be analyzed for color uniformity.

[0032] More precisely, the control unit 10 is configured to measure the internal and external variability indices of the tablet's color.

[0033] For the definition of these indices, we consider groups consisting of 100, 101 tablets, each with a number equal to N belonging to selected tablets without shading, and in particular, the image of each tablet acquired by the visual system 3.

[0034] M j Let be defined as the number of pixels belonging to the image of the jth tablet,

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[0035] Next, the average internal distance associated with the jth tablet

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[0036] For example, referring particularly to Figures 5a and 5b, a low internal variability index indicates high color homogeneity or uniformity on the surface of a single tablet, i.e., there are no areas or zones without color and / or areas or zones with different intensities on this surface (Figure 5a). Conversely, a high internal variability index indicates low color homogeneity or uniformity on the surface of a single tablet, i.e., there are one or more areas or zones without color and / or areas or zones with different intensities on the surface (Figure 5b). In particular, in Figure 5a, the color is distributed with substantially uniform intensity and is therefore shown with one type of hatching, while in Figure 5b, parts of the tablet are colorless and therefore have no hatching.

[0037] Furthermore, the average color of the group under consideration of N tablets of types 100 and 101 belonging to the selected tablets without shading was examined in a triad.

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[0038] Therefore, for the group under consideration of N tablets of type 100 and 101 belonging to the selected tablets without shading, the external distance vector

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[0039] In this way, the external variability index for the group under consideration of N tablets of types 100 and 101 belonging to the selected tablets without shading is the external distance vector.

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[0040] For example, referring particularly to Figures 6a and 6b, a low external variability index indicates low color diversity between the surfaces of a group of tablets, i.e., high surface color homogeneity or uniformity (Figure 6a). Conversely, a high external variability index indicates significant color diversity between the surfaces of a group of tablets, i.e., low surface color homogeneity or uniformity (Figure 6b). In particular, in Figure 6a, the tablets have virtually uniform color distribution, so all tablets have the same hatching, while in Figure 6b, the tablets each have different colors, so their hatching is different.

[0041] Therefore, based on the above definition, the internal variability index

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[0042] Generally, the threshold for the variability index below which color differences are considered negligible is equal to 3.

[0043] This threshold was derived experimentally.

[0044] Alternatively, using the visual system 3, it is possible to analyze tablet 100 belonging to a standard manufacturing batch, i.e., a reference batch, calculate relative internal and external variability indices considered as reference, and then compare these reference indices with the internal and external variability indices obtained for other tablets subject to coating quality control.

[0045] Another alternative approach involves analyzing the temporal development of variability indices obtained for selected and analyzed tablets 100, and detecting potential degradation in the performance of the coating process performed by the coater machine 50 based on unexpected changes in these variability indices.

[0046] The visual means 3 includes, for example, a camera.

[0047] Referring particularly to Figure 3, the dome illuminator 2 comprises a dome-shaped vault 21 having an internal reflective surface 23 and a peripheral internal flange 24, particularly having a circular base 22. The peripheral internal flange 24 is provided at the base 22 and comprises a plurality of light sources 25, particularly LED type light sources 25, suitable for diffusing light toward the internal reflective surface 23, and the internal reflective surface 23 allows the light to be uniformly diffused downward, i.e., toward the base 22. The dome vault 21 comprises an upper central opening 26, coaxial with the vertical axis of symmetry Z of the dome vault 21, for example, enabling the visual means 3 to detect an image of the tablet 100 inside the dome illuminator 2 in the detection zone B of the exit chute 51.

[0048] The operation of System 1 according to the present invention for analyzing coatings on tablets, pills, capsules, etc. for pharmaceutical and / or food applications produced by a coater machine 50 is defined as follows: the coated tablets 100 exiting the coater machine 50 are analyzed by the visual means 3 and control unit 10 as they slide by gravity along an exit chute 51 in the exit direction A.

[0049] More precisely, the tablet 100 is illuminated in detection zone B of the descent plane 52 of the exit chute 51 by a dome illuminator 2 configured to emit and diffuse light uniformly and homogeneously.

[0050] This illumination allows the control unit 10 to analyze only the outer surfaces of single, separated tablets whose maximum extended surface is exposed to the visual means 3, based on the image of the tablets 100 detected by the visual means 3. Therefore, the outer surfaces of the selected tablets are used to evaluate color uniformity, particularly the internal variation index.

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[0051] Based on the results of this analysis, it is possible to modify the operating parameters of the coater machine 50, especially if the measured variability index value deviates from the reference variability index.

[0052] For this purpose, the coater machine 50 comprises a processing unit 60 connected to the control unit 10 of System 1, and is configured to change operating parameters based on information provided by the control unit 10 regarding the uniformity of the color of the outer surface of the selected and coated tablets. In particular, the operating parameters include the tablet inlet flow rate, the rotational speed of the rotating drum 55, and the flow rate of the coating material discharged by the sprayer 57 onto the tablets.

[0053] The present invention provides a method for analyzing coatings on tablets, pills, capsules, etc., for pharmaceutical and / or food applications, in a tablet coater machine 50 equipped with an outlet chute 51 for dispensing coated tablets 100. The steps include: illuminating the detection zone B of the descent plane 52 of the exit chute 51 with a dome illuminator 2, as the tablet 100 descends by gravity along the exit direction A; The steps include detecting an image of the tablet 100 moving on the descending plane 52 using a visual means 3 associated with the dome illuminator 2, The steps include: using a control unit 10 connected to a visual means 3 to receive images of tablets 100, and analyzing only the images of selected tablets without shading; A step of evaluating the uniformity of the color of the outer surface of the selected tablets, Includes.

[0054] According to the method of the present invention, the selected tablets without shading include single, separated tablets whose maximum extended surface is exposed to the visual means 3.

[0055] The method includes detecting an image of the tablet 100 using a visual means 3, which includes, for example, a camera.

[0056] According to the method, the uniformity of the color of the outer surface of selected tablets is evaluated by measuring the internal color variation index of 100 selected tablets according to the following formula:

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[0057] Therefore, the system and method of the present invention make it possible to analyze a large number of tablets 100 automatically, easily, economically, and without operator intervention at the outlet of a coater machine 50, particularly a continuous flow type coater machine.

[0058] The visual means 3 and dome illuminator 2 associated with the exit chute 51 of the coater machine 50 make it possible to analyze the moving tablets 100, i.e., the tablets 100 that are descending by gravity along the exit direction A on the descent plane 52 of the exit chute 51.

[0059] Since the control unit 10 analyzes only images of the tablets 100 detected by the visual means 3 that are free of shading, i.e., images of single, separated tablets whose maximum extending surface is exposed to the visual means 3, the system 1 of the present invention allows for the analysis of the coating quality of the tablets 100, particularly the internal variation index of the coating of the tablets 100 processed by the coater machine 50.

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Claims

1. A system (1) for analyzing the coating of tablets, pills, or capsules for pharmaceutical or food applications, which can be associated with a tablet, pill, or capsule coater machine (50), An outlet chute (51) configured to be associated with the coater machine (50) for dispensing coated tablets, pills, or capsules (100, 101), A dome illuminator (2) is positioned to illuminate a detection zone (B) on the descent plane (52) of the exit chute (51) along which the tablets, pills, or capsules (100, 101) descend by gravity along the exit direction (A), A visual means (3) associated with the dome illuminator (2) and arranged to detect an image of the tablet, pill, or capsule (100, 101) moving on the descending plane (52), A system (1) comprising: a control unit (10) configured to receive images of the tablets, pills, or capsules (100, 101), track the movement of each tablet, pill, or capsule (100, 101), select only those tablets, pills, or capsules without shading, analyze the images of the selected tablets, pills, or capsules, and evaluate the uniformity of the color of the outer surface of the selected tablets, pills, or capsules.

2. The system (1) according to claim 1, wherein the visual means (3) includes a camera.

3. The aforementioned dome illuminator (2) The dome vault (21) has a bottom portion (22) and is provided with an internal reflective surface (23) and a peripheral internal flange (24) located on the bottom portion (22) and equipped with a plurality of light sources (25) suitable for diffusing light toward the internal reflective surface (23), The aforementioned dome vault (21) The system (1) according to claim 1 or 2, further comprising an upper central opening (26) that enables the visual means (3) to detect an image of the tablet, pill, or capsule (100, 101) within the dome illuminator (2).

4. The variation in color within a single selected tablet, pill, or capsule is defined as internal variation. The color variation among multiple selected tablets, pills, or capsules is defined as external variation. The control unit (10) is configured to measure the internal color variation index of the selected tablets, pills, or capsules (100, 101) according to the following formula: [Math 1] Here, [Math 2] This is the average internal color distance associated with the jth tablet, pill, or capsule in the CIELAB color space, and the internal variation index evaluates the color homogeneity of the surface of each tablet, pill, or capsule viewed individually, and The control unit (10) is configured to measure the external color variation index of the selected tablets, pills, or capsules (100, 101) according to the following formula: [Math 3] Here, [Math 4] The system (1) according to claim 1 or 2, wherein is a vector of external distances of the colors associated with the aforementioned j tablet, pill, or capsule in the CIELAB color space, and the external variation index evaluates the color diversity among a plurality of tablets, pills, or capsules.

5. Of the one or more surfaces included in the detected image of the tablet, pill, or capsule, the surface with the largest area is defined as the maximum extending surface. The system (1) according to claim 1, wherein the control unit (10) is configured to track the movement of each tablet, pill, or capsule (100, 101) and to analyze only the image of a single, separated tablet, pill, or capsule in which the maximum extending surface is exposed to the visual means (3).

6. A continuous coater (50) for coating tablets, pills, or capsules, comprising a system (1) for analyzing the coating of tablets, pills, or capsules (100, 101) as described in claim 1.

7. The continuous coater (50) according to claim 6, further comprising a processing unit (60) connected to a control unit (10) of the system (1) and configured to modify the processing operation parameters of the coater (50) based on information provided by the control unit (10) regarding the uniformity of the color of the outer surface of the coated tablets, pills, or capsules.

8. A method for analyzing the coating of tablets, pills, or capsules for pharmaceutical and / or food applications in a tablet, pill, or capsule coater (50) equipped with an outlet chute (51) for dispensing coated tablets, pills, or capsules (100, 101), The detection zone (B) of the descent plane (52) of the exit chute (51) along which the tablets, pills, or capsules (100, 101) descend by gravity along the exit direction (A) is illuminated by a dome illuminator (2), Using the visual means (3) associated with the dome illuminator (2), an image of the tablet, pill, or capsule (100, 101) moving on the descending plane (52) is detected, Using a control unit (10) connected to the visual means (3) to receive images of the tablets, pills, or capsules (100, 101), the movement of the tablets, pills, or capsules (100, 101) is tracked, only tablets, pills, or capsules without shadows are selected, and the images of the selected tablets, pills, or capsules are analyzed. A method comprising evaluating the uniformity of the color of the outer surface of the selected tablet, pill, or capsule.

9. Of the one or more surfaces included in the detected image of the tablet, pill, or capsule, the surface with the largest area is defined as the maximum extending surface. The method according to claim 8, wherein the selected unshaded tablets, pills, or capsules include a single, separated tablet, pill, or capsule whose maximum extended surface is exposed to the visual means (3).

10. The method according to claim 8 or 9, further comprising detecting the image of the tablet, pill, or capsule (100, 101) by visual means (3) including a camera.

11. The variation in color within a single selected tablet, pill, or capsule is defined as internal variation. The color variation among multiple selected tablets, pills, or capsules is defined as external variation. Evaluating the uniformity of the color of the outer surface of the selected tablets, pills, or capsules (100, 101) includes measuring the internal color variation index of the selected tablets, pills, or capsules (100, 101) according to the following formula: [Math 5] Here, [Numeral 6] This is the average internal color distance associated with the jth tablet, pill, or capsule in the CIELAB color space, and the internal variation index evaluates the color homogeneity of the surface of each tablet, pill, or capsule viewed individually, and The evaluation described above includes measuring the external variability index of the color of the selected tablets, pills, or capsules (100, 101) according to the following formulas: [Number 7] Here, [Number 8] The method according to claim 8 or 9, wherein is a vector of external color distances in the CIELAB color space relating to the aforementioned tablet, pill, or capsule, and the external variation index evaluates the color diversity between a plurality of tablets, pills, or capsules.

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